The Role of Starburst in the Chemical Evolution of Galaxies

应⽤化学专业英语第⼆版万有志主编版课后答案和课⽂翻译Unit 1 The Roots of ChemistryI. Comprehension.1.C2. B3. D4. C5. BII. Make a sentence out of each item by rearranging the words in brackets.1.The purification of an organic compound is usually a matter of considerable difficulty,and it is necessary to employ various methods for this purpose.2.Science is an ever-increasing body of accumulated and systematized knowledge and isalso an activity by which knowledge is generated.3.Life, after all, is only chemistry, in fact, a small example of chemistry observed on asingle mundane planet.4.People are made of molecules; some of the molecules in people are rather simplewhereas others are highly complex.5.Chemistry is ever present in our lives from birth to death because without chemistrythere is neither life nor death.6.Mathematics appears to be almost as humankind and also permeates all aspects ofhuman life, although many of us are not fully aware of this.III. Translation.1.(a) chemical process (b) natural science (c) the technique of distillation2.It is the atoms that make up iron, water, oxygen and the like/and so on/and soforth/and otherwise.3.Chemistry has a very long history, in fact, human activity in chemistry goes back toprerecorded times/predating recorded times.4.According to/From the evaporation of water, people know/realized that liquids canturn/be/change into gases under certain conditions/circumstance/environment.5.You must know the properties of the material before you use it.IV. Translation化学是三种基础⾃然科学之⼀，另外两种是物理和⽣物。

a r X iv:as tr o -p h /0307556v 1 31 J u l 2003Astronomy &Astrophysics manuscript no.LSB˙accept February 2,2008(DOI:will be inserted by hand later)Starburst in HS 0822+3542induced by the very blue LSB dwarfSAO 0822+3545S.A.Pustilnik 1,4,A.Y.Kniazev 1,2,4,A.G.Pramskij 1,4,A.V.Ugryumov 1,4,and J.Masegosa 31Special Astrophysical Observatory RAS,Nizhnij Arkhyz,Karachai-Circassia,369167Russia 2Max Planck Institut f¨u r Astronomie,K¨o nigstuhl 17,D-69117,Heidelberg,Germany3Instituto de Astrofisica de Andaluc ´ia,Granada,Spain4Isaac Newton Institute of Chile,SAO BranchReceivedFebruary 26,2002;acceptedJuly 30,2003Abstract.One of the most metal-deficient blue compact galaxies (BCGs)HS 0822+3542(Z =1/34Z ⊙),is also one of the nearest such objects (D ∼11Mpc).It is in addition well isolated from known bright galaxies.A trigger mechanism for its current star-formation (SF)burst has thus remained unclear.We report the discovery of a veryblue ((B −V )0tot =0.08and (V −R )0tot =0.14)low surface brightness (LSB)(µ0B 23.m 4arcsec−2)dwarf irregular (dIrr)galaxy,which we have named SAO 0822+3545.Its small relative velocity and projected distance of only ∼11kpc from the BCG imply their physical association.For this LSB dIrr galaxy,we present spectroscopic results,total B,V,R magnitudes,and the effective radii and surface brightness (SB),and we describe its morphological properties.We compare the very blue colours of this dwarf with PEGASE.2models of the colour evolution of a Z =1/20Z ⊙stellar population,and combine this analysis with the data on the LSBD EW (H α)values.The models best describing all available observational data depend on the relative fraction of massive stars in the IMF used.For a Salpeter IMF with M up =120M ⊙,the best model includes a “young”single stellar population (SSP)with an age of ∼10Myr and an “old”SSP with the age of ∼0.2–10Gyr.The mass ratio of the old to young components should be in the range of 10to 30.If the age of the old component is more than ∼1Gyr,an additional coeval component of “intermediate”age (∼100Myr)with a mass comparable to that of the “young”population,although not required,provided a good fit to the current data.For the two options of a model IMF biased toward the low-mass end,the best match of the observed BV R and EW(H α)is for continuous star-formation rate (SFR)single-component models,with SF durations in the range of ∼0.1to ∼1Gyr.However,only a longer time-scale SF gives the stellar mass,compatible with the LSB galaxy mass estimates.Nevertheless,such a scenario would be inconsistent with the recent encounter of these two dwarfs.The role of interaction between the LSBD and BCG HS 0822+3542in triggering their major SF episodes during the last ∼100–200Myr is emphasized and discussed.For the BCG,based on the results of new spectroscopy with the Russian 6m telescope,we estimate the physical parameters of its SF region and present the first evidence of an ionized gas supershell.This pair of dwarfs lies deep within the nearby Lynx-Cancer void,with the nearest bright (L >L ∗)galaxies at distances >3Mpc.This is probably one of the main factors responsible for the unevolved state of HS 0822+3542.Key words.galaxies:star formation –galaxies:low surface brightness –galaxies:interaction –galaxies:photometry –galaxies:abundances –galaxies:individual (HS 0822+3542,SAO 0822+3545)–large-scale structure1.IntroductionA few known blue compact galaxies (BCGs)with ex-tremely low metallicities (1/50to 1/20Z ⊙)are considered to be the best candidates for truly young local low-mass galaxies,in which we are witnessing the first star forma-tion episode,with the oldest stars formed less than ∼100–200Myr ago.The best known examples are SBS 0335−052(Izotov et al.1997;Papaderos et al.1998;Pustilnik et al.2001a),and I Zw 18(Searle &Sargent 1972;Izotov1Note that debates on the possible youth of these BCGsstill continue in the literature (see,e.g.,the most recent ¨Ostlin2000;¨Ostlin &Kunth 2001;Kunth &¨Ostlin 2001).2S.A.Pustilnik et al.:Starburst in HS0822+3542induced by SAO0822+3545van Zee et al.1998,Izotov et al.2001).This,presumably, is a key moment of their history.Moreover,it is probably not by chance that in both the cases of Dw1225+0152 and SBS0335−052E the nearest neighbour is very gas-rich,and either is an H i cloud without any hint of past star formation(as in the case of Dw1225+0152,Salzer et al.1991),or is also an extremely metal-deficient,proba-bly truly young,blue compact galaxy(SBS0335−052W, Pustilnik et al.1997;Lipovetsky et al.1999).Low surface brightness galaxies(LSBGs)comprise a large fraction of the generalfield galaxy population and outnumber by a factor of several times the high sur-face brightness(HSB)population(e.g.,McGaugh1996, Dalcanton et al.1997,O’Neil&Bothun2000).Therefore, these LSBGs can be an important factor for interaction-induced star-formation activity in gas-rich galaxies in gen-eral,mostly through distant/weak tidal encounters(see, e.g.,Taylor et al.1995;O’Neil et al.1998;Pustilnik et al. 2001b).In particular,through interaction they can trig-ger thefirst starbursts in the hypothetical population of local protogalactic H i clouds.To check this hypothesis the authors are conducting a systematic study of the lo-cal environment of the most metal-deficient BCGs.We present here new evidence in support of this idea.We re-port the discovery of a LSB dwarf irregular galaxy(named SAO0822+3545)at a projected distance of∼11.4kpc from one of the most metal-deficient BCGs,HS0822+3542 (Kniazev et al.2000).We have used the SAO RAS6m telescope spectrum in the Hαregion,as well as BV R photometry from the Nordic Optical Telescope(NOT)to study its properties and estimate its tidal effect on the BCG HS0822+3542.We also present new high signal-to-noise(S/N)6m telescope spectra for HS0822+3542which allow us to make more accurate measurements of some of the physical parameters of its star-forming(SF)region and discover thefirst kinematic evidence of an ionized gas supershell.In Section2we describe the observations and their reduction.Results of the data analysis are presented in Section3.We discuss these results in Section4,and summarize ourfindings and draw conclusions in Section5.2.Observations and reduction2.1.Nordic Optical Telescope photometryThere are no cataloged galaxies around HS0822+3542in either NED or LEDA databases with V hel<1200km s−1 and projected distances less than 5.8◦.To search for fainter/non-cataloged galaxies in the close vicinity of this BCG we used B,V,R CCD images obtained with the2.5m NOT on May28,1998.These are the same frames which were used to derive B,V,R magnitudes for HS0822+3542. They were acquired with the ALFOSC spectrograph equipped with the LORAL(W11-3AC)CCD,which has a direct imaging mode.Exposure times were900s for the B-band image,and600s for both V and R images.For further details of these observations and data reduction we refer to the paper by Kniazev et al.(2000).2.2.Looking for possible companionsThe photometric data were reduced with MIDAS2 Command Language programs according to the method described in Kniazev(1997).The MIDAS INVENTORY package was used to classify all objects.Isophotal and total BV R magnitudes were computed using the trans-formation coefficients of Kniazev et al.(2000).Since the interaction between HS0822+3542and a possible neighbouring galaxy would probably result in some enhanced star formation in the latter,wefirst of all searched for candidate blue galaxies.The second criterion applied was that the brightness of any candidates should be comparable to that of HS0822+3542,since signifi-cantly fainter neighbours could tidally affect the BCG only from very small distances(see,e.g.,estimates in Pustilnik et al.2001b).Only two blue galaxies were found in the examined field.Thefirst one is HS0822+3542itself.The second is a LSB irregular galaxy(SAO0822+3545)at3.5′to the north-east from HS0822+3542(its coordinates are given in Table5).The Digitized Sky Survey(DSS-II)blue image of thisfield with the2objects of interest and Anon J0825+3534is presented in Fig.1.All other galaxies in the NOTfield were either significantly fainter or redder.2.3.Analysis of photometric dataWe performed the reduction of photometric data for SAO0822+3545using the IRAF3package ELLIPSE.The growth curve(GC)of the galaxy was constructed by sum-ming up the pixel values from the center outwards in the circles of successive radius.The total magnitudes(B tot,V tot,R tot)were estimated by asymptotic extrapolation of the respective radial GCs. Model-independent parameters were derived from each growth curve.The effective radii(r eff)were read on each GC at one half the asymptotic intensity,and effective SBs (SB eff)were determined as the mean brightness within a circle with the effective radius.These values are summa-rized in Table2.2.4.Long-slit spectroscopySpectroscopic data were obtained with the6m tele-scope of the Special Astrophysical Observatory of Russian Academy of Sciences(SAO RAS).The long-slit spec-trograph(LSS)(Afanasiev et al.1995)was used with a Photometrics1024×1024pixel CCD detector with a 24µm pixel size.The wavelength ranges of the spec-tra obtained for different hardware configurations areS.A.Pustilnik et al.:Starburst in HS0822+3542induced by SAO0822+35453Fig.1.The Digitized Sky Survey(DSS-II)blue image of thefield in the vicinity of BCG HS0822+3542.North is up, East is to the left.At the adopted distance of HS0822+3542(11Mpc)the scale is∼54pc=1′′.The two marked galaxies–LSBD SAO0822+3545and Anon J0825+3534have been checked as possible companions of the BCG.On our data the LSBD has V hel∼700km s−1,close to that of HS0822+3542.Its projected distance to the BCG is213′′or 11.4kpc.The galaxy Anon J0825+3534,very close to the position of2MASXi J0825440+353459(NED),is a distant background object with V hel=15590km s−1.Table1.Journal of the6m telescope spectroscopic observationsObject Date Exposure Wavelength Dispersion Seeing Airmass PAtime[s]Range[˚A][˚A/pixel][arcsec][degree](1)(2)(3)(4)(5)(6)(7)(8)4S.A.Pustilnik et al.:Starburst in HS 0822+3542induced by SAO0822+3545Fig.2.Top panel:2D spectrum of SAO 0822+3545with the H αline at λ6579˚A .Positive Y corresponds to the NW direction for the slit position shown in Fig.3.H α-emission is clearly seen on top of the continuum in the region of ±∼5′′from the central position.Furthermore,some very faint H α-emission (with S/N ratio of ∼1)can be traced out to ±∼10′′,in the regions without detectable continuum.Bottom panel:1D spectrum of the central region (±3′′),summed along the slit,EW (H α)=17˚A .grating,giving a sampling of 1.2˚A pixel −1and an effec-tive resolution (with the 2′′slit width)of 3.5˚A .Seeingduring these observations was 1.7′′.For the reduction of 2D spectra we obtained biases,flat fields and illumination correction images.The primary re-duction consisted of standard steps and was done using the IRAF package CCDRED .The IRAF package LONGSLIT was used to perform wavelength calibration,background subtraction,extinction correction and flux calibration.Straightening of the 2D spectra was performed using APALL ,another IRAF package.After that,aperture ex-tractions,continuum determination,flux and equivalent width measurements of spectral lines were performed in MIDAS (for details,see Kniazev et al.2000).The reduced 2D spectrum and extracted averaged 1D spectrum of SAO 0822+3545are shown in Fig.2.Fluxes and equivalent widths of blended lines were measured using Gaussian decomposition fitting.An av-erage sensitivity curve was produced for each night with r.m.s.deviations of 5%in the whole spectral range.The sensitivity curve and line intensity errors have been prop-agated in calculating elemental abundances.To construct the P–V diagram,the methodology described in Zasov et al.(2000)was used,which allowed us to measure points with sufficiently bright H αemission with r.m.s.errors on the level of 2–4km s −1.3.Results3.1.Spectrum of SAO 0822+3545The 2D spectrum of SAO 0822+3545in Fig.2shows H αemission spanning ∼10′′,comparable to the appar-ent extent of the galaxy continuum.Some fainter H αfea-tures can be detected in the peripheral regions,where no continuum is seen in our spectrum.The equivalent width of the H αline,measured on the 1D spectrum av-eraged over the central region with the a spatial extent of 6′′,is EW (H α)=17±2˚A .The integrated flux in thisline is 4.65(±0.55)×10−16erg s −1cm −2.Small variations of EW (H α)along the slit near the center of the galaxy on the level of ∼15−20˚A are within the observa-tional uncertainties.Closer to the edges the EW (H α)can be larger,but there the uncertainty reaches 70–100%,so we do not discuss these regions further.The measured velocity V hel =700±50km s −1is very close to that of HS 0822+3542.3.2.Photometry and morphology of SAO 0822+3545We calculated total magnitudes B tot =17.56±0.05,V tot =17.43±0.03and R tot =17.26±0.05for SAO 0822+3545us-ing the growth curve method as described in Sec.2.3.The respective integrated colours are (B −V )tot =0.13and (V −R )tot =0.17.Relatively large errors originate from the zero-point uncertainties of the transformation equa-tions (Kniazev et al.2000).Accounting for a foreground extinction of E (B −V )=0.047in our Galaxy (Schlegel et al.1998),and applying the extinction curve from Whitford (1958),these colours become somewhat bluer:(B −V )0tot=0.08±0.06,(V −R )0tot =0.14±0.06.The 2D spectrum in Fig.2and the irregular structure of the central part of SAO 0822+3545(see Fig.3)indicate that enhanced star formation took place at least in the inner part of that galaxy.The possibility of better distin-guishing individual regions of higher brightness (possible young superclusters and aged H ii regions)in the central part of the LSBD was the motivation for using the MIDAS package IMRES for deconvolution of the NOT images.This package employs an image restoration scheme devised by Richardson and Lucy and described in Adorf et al.(1992),Hook &Lucy (1992;and references therein).The num-ber of iterations was determined by comparisons between the input image and the output deconvolved images,after convolution with the point-spread function (PSF).The results of deconvolving the B -band image after 15iterations are plotted in the right panel of Fig.3.A number of filaments and relatively bright knots in the inner part of this LSB/dIrr galaxy are well resolved.Practically all of them are seen on the original image (left panel of Fig.3),although deconvolution makes the structure more visible.All these structures are easily visible in a deconvolved V -band image,but are less distinct in R -band.There is a faint tail in the SE direction in the outer part of the LSBD.This tail is visible on both blue DSS-S.A.Pustilnik et al.:Starburst in HS 0822+3542induced by SAO 0822+35455Fig.3.Left panel:Thesame B -band image of SAO 0822+3545,deconvolved after 15iterations using the FFT based Lucy algorithm (Adorf et al.1992).The angular resolution has improved from 1.′′25to ∼0.′′85(FWHM).Several filaments and many knots are easily visible within the brighter part of the galaxy.Knots are marked by letters from “a”to “i”,respectively.II and B -band NOT images.The surface brightness of this tail corresponds to µB =25.m 7arcsec −2,or 2σof the noise level for the B -band image.The tail direction coincides with that of the LSBD major axis.The major axis P A varies from –75◦for the inner part of the galaxy up to –60◦for the outer part.The axial ratio is essentially constant over the body:b/a ∼0.55.Evidence for recent star-formation activity over the in-ternal part of this dIrr galaxy is also seen,e.g.,in the (B −V )0colour map (Fig.4).This map shows a rather uniform distribution (mainly in the range from –0.05to +0.10)over a large part of the main body.Its maximum (+0.2to +0.25)and minimum (–0.15to –0.10)values are measured in the positions close to the edges,where the S/N is small,and these large colour variations are appar-ently spurious.SAO 0822+3545is a genuine LSB galaxy with traces of recent SF near its center.Since the central bright knots are seen with the lowest contrast in R -band,we made a rough estimate of the central SB of an underly-ing “disk”in R .From the data in Table 2,its effective surface brightness corrected for extinction (A R =0.12)isµR eff,0=23.m 63arcsec−2.For a purely exponential disk this corresponds to a central brightness of µR 0=22.m 50arcsec −2.Since the galaxy is significantly inclined to the line-of-sight,we need to make a corresponding correction to µR 0.For an observed axial ratio p =b/a =0.55,assuming anintrinsic axial ratio of q =0.2,and using the well-known formula cos 2(i )=(p 2−q 2)/(1−q 2),we calculate that i =58.5◦.The inclination correction for surface brightness is then −2.5·log(cos i )=0.m 7,giving a corrected centralbrightness of µR0,c =23.m 20arcsec −2.Even if the underly-ing “disk”is as blue,as the integrated light of this galaxy (that is,(B −R )0∼0.2),its central brightness in B -bandµB 0,c =23.m 40arcsec−2is well within the LSB galaxy regime.For an exponential law,r eff=7.94′′in R corresponds to the scalelength αR =4.73′′.Table 2.Photometric parameters of SAO 0822+3545BandTotal r effSB effmag arcsec mag arcsec −2(1)(2)(3)6S.A.Pustilnik et al.:Starburst in HS 0822+3542induced by SAO0822+3545Fig.4.Grey-scale map of (B −V )-colour for SAO 0822+3545smoothed with 2D median with the win-dow size of 1.′′6×1.′′6.The extinction corrected (E (B −V )=0.047)colour distribution is shown only for regions with S/N ratio larger than 4.The colour scale is shown in the right side column.B -band surface brightness (SB)isolines are superimposed,with the lowest SB level of 25.m 7arcsec −2.The other levels are:24.5,24.0,23.6,23.3,23.1,22.9,22.8and 22.6mag arcsec −2.tor of two (FWHM=0.′′6),and the restored BCG complex morphology is shown in Fig.5in grey scale,with a contour indicating the outer isophote µB =25.m 0arcsec −2super-imposed.With the letters “a”to “f”we have marked all bright features well resolved after deconvolution in each of B,V ,and R bands.The brightest region consists of two components,“a”and “b”,separated by ∼1.3′′(∼70pc),roughly in the N–S direction.The contrast in Fig.5is adjusted to show faint features.The real ratio of the intensities of knots “a”and “b”,derived from this image,is ∼8.While deconvolution does not preserve brightness proportions between individual features,we consider this ratio to be indicative of the real value.In addition to several bright knots,some filamen-tary structures are also visible.Some traces of them are also seen in other filters,but due to their lower surface brightness they are not as easily visible as the knots.Nevertheless,the prominent arc-like structure at the NW edge of the main body (stretching from X =+2,Y =+4to X =+6,Y =+4in Fig.5),is clearly visible on both B and V images,but is more noisy in R -band,presumably due to the lower S/N ratio.This feature probably repre-sents an ionized gas shell with a diameter of ∼4′′(∼200pc),caused by recent active SF in this region,Four more knots are seen in the restored image.One (“d”)is near the geometrical center of the main body.This,perhaps,might naturally be expected because of the gravitational well in the center of the galaxy.The others knots provide further evidence that the current SF episode in the BCG is spread across the galaxy.The P–V diagram in Fig.6indicates a supershell with a size of ∼480pc,comparable to the extent of H α-emission in the long-slit direction.The supershell velocity ampli-tude,as seen from our data,is about 30km s −1.Such supershells are well-resolved on high-resolution H αlong-slit spectra for many nearby starbursting galaxies (e.g.,Marlowe et al.1995;Martin 1996,1997,1998).The re-lated supershells of neutral gas are also seen in H i maps of such galaxies (e.g.,Walter &Brinks 1999).For the typ-ical case of a starburst off-set in position relative to the midplane of the gas disk,the asymmetry of the gas den-sity distribution in the z -direction results in the shell’s asymmetric appearance.This was shown,e.g.,in numer-ical simulations by Silich et al.(1996),and by Walter &Brinks (1999)for the observed types of P–V diagrams.That part of the shell propagating out of the plane should have a significantly lower Emission Measure due to de-creasing gas density,and usually appears much fainter in comparison to the part of the shell moving towards the midplane (e.g.,Martin 1996).Shells (or supershells)are produced by hot bubbles,caused by the injection of the energy from numerous massive star winds and supernova (SN)explosions into the interstellar medium (ISM)(e.g.,Tenorio-Tagle &Bodenheimer 1988).The asymmetric appearance of super-shells in H αemission is easily seen with the high-resolution data mentioned above.When the velocity resolution is not sufficient to distinguish motions on both sides of the shell,we measure the intensity-weighted velocity in the H α-line at each slit position.If the H αintensities in the segments on opposite sides of the shell differ significantly,we will see mainly the side approaching the midplane of the gas disk.However,since the observed velocity at each slit position is the weighted mean of the emission from the opposite sides of the shell,a shell velocity derived in this way rep-resents a lower limit of the real value.Depending on the relative strengths of H αemission on the shell sides the expected correction could reach tens of percent.If we accept the full amplitude of the radial veloc-ity difference between the two edges on the P–V di-agram (∼35km s −1)as the result of rotation in the BCG,then the apparent V rot is 17.5km s −1.With an apparent axial ratio p =b/a =0.5,and an assumed in-trinsic ratio q =0.2,using the same relation as for SAO 0822+3545in section 3.2we get an inclination an-gle i =63.6◦,and thus an inclination-corrected value of V rot =19.5km s −1.The latter value is quite consistent with that expected from the Tully-Fisher relation be-tween galaxy V rot and its blue luminosity,namely,using the relations derived by Karachentsev et al.(1999)for dwarf galaxies in the Local Volume.For HS 0822+3542,M B =–12.5(or L B =1.56×107L ⊙)and so the expected V rot =17km s −1,with a ±1σconfidence range of 12to 24km s −1.S.A.Pustilnik et al.:Starburst in HS 0822+3542induced by SAO 0822+35457Fig.6.Upper panel:P–V dia-gram of ionized gas in HS 0822+3542based on the H αline from the same spectrum.Its form within a radius of ±4′′,and the characteristic diameter and velocity ampli-tude (∼480pc and ∼30km s −1),are consistent with the appearance of supershells observed in many star-bursting galaxies.Filled boxes show the velocities on both sides of the shell as derived from the Gaussian decomposition of the H αline at several positions along the slit.For details see section 3.3.In Fig.6we use filled squares to show the velocities on both sides of the shell,obtained by Gaussian decom-position of the H αprofiles.The two-component struc-ture is detectable only for sufficiently large S/N ratios and maximal velocity separation.The flux from the re-ceding components is several times lower than that from the approaching ones.These data confirm the existence of a large shell with a characteristic velocity amplitude of ∼30km s −1and exclude the interpretation of this feature in the P–V diagram as part of a rotation curve.Indeed,the rotation velocity should monotonously increase from one edge to another.The real P–V diagram certainly does not look like this.Thus,if the ionized gas in the BCG is rotating,its rotation velocity is sufficiently small to be practically hidden by the visible large shell.3.4.Chemical abundances in HS 0822+3542The spectrum of the brightest knot of HS 0822+3542,ex-tracted with an aperture of 3.′′6×1.′′2,is shown in Fig.7.It is dominated by very strong emission lines.The rel-ative intensities of all emission lines,together with the equivalent width EW (H β),extinction coefficient C (H β)and the EW of Balmer absorption lines are given in Table 3.C (H β)was derived from the Balmer decrementusing the self-consistent method of Izotov et al.(1994).The derived value of C (H β)=0.0±0.09is consistent,to within the uncertainties,with a reddening of E (B −V )=0.047±0.007,expected from foreground extinction in the Galaxy (Schlegel et al.1998).We analyzed chemical abundances and physical pa-rameters with the method described by Kniazev et al.(2000).The measured electron temperatures and den-sity,and derived chemical abundances are presented in Table 4.Our new data give a slightly higher value of 12+log(O/H)(7.44±0.06versus 7.35±0.04from the NOT spectrum),but the difference is not significant.The main source of this difference is the intensity of the [O iii ]λ4363line,relative to H β.Its measured value is 0.104on the 6m telescope spectrum,in comparison to 0.123on the NOT spectrum.Part of the derived differences in O/H could be due to the differences in observational conditions,resulting in the sampling of slightly different regions.However,both results are in fact consistent to within their uncertainties.The ratios of other heavy element abundances (Ne ,S ,N )to that of oxygen,derived from the NOT and the 6m tele-scope data,are also similarly consistent.With the higher resolution (1.2˚A pixel −1)spectrum near H αwe improved the precision of the N abundance,since the [N ii ]λ6584emission line was detected with a higher S/N ratio than in the NOT spectrum.The intensities of Ar lines are mea-sured for the first time in this BCG,and we present here its abundance.At the position of the [Fe iii ]line λ4658˚A we detected a signal at a level of 4σ.However,if log(Fe/O)is typical of other very metal-poor BCGs (∼−1.65),the signal in this line should be only ∼1.3σ.One possible ex-planation of the strength of this line is the contribution of the WR spectral feature C iv λ4658.In many BCGs with detected WR features the intensity of the C iv λ4658line is comparable to that of He ii λ4686(e.g.,Guseva et al.2000).Thus,a likely interpretation of the observed fea-ture is that it is the sum of the lines of [Fe iii ]and C iv .This suggests that higher S/N spectroscopy could detect the other WR features in this young starburst region.The He ii λ4686line in our spectrum is broadened to ∼15˚A ,but the S/N ratio is too low to accept this as direct evi-dence of a WR population.4.Discussion4.1.General parameters of the systemIn Table 5we present the main parameters relevant for further discussion of the properties and status of these dwarf galaxies.Their small mutual projected dis-tance (3.′5,or ∼11kpc)and relative velocity (∆V <25km s −1,Chengalur et al.2003)imply that both galaxies are physically associated.Some of the param-eters for HS 0822+3542in Table 5have been revised from those in Kniazev et al.(2000).In particular,the distance-dependent parameters have changed due to an improved distance estimate.H i related parameters have also changed due to correction of the 21-cm line flux8S.A.Pustilnik et al.:Starburst in HS 0822+3542induced by SAO0822+3545Fig.5.Left panel:Same as before,but for NOT V -band image.The filamentary structure on NW edge iswell seen on both images.(GMRT,Chengalur et al.2003).The integrated H i flux presented by Kniazev et al.(2000),based on observations with the NRT,appeared to be offby a factor of two due to the effects of confusion with the galaxy SAO 0822+3545.The adopted oxygen abundance is the weighted mean of current and previous (Kniazev et al.2000)values.4.2.On the evolutionary status of SAO 0822+35454.2.1.The very blue colours of SAO 0822+3545The integrated colours of SAO 0822+3545are unusually blue.Only two out of about 250LSB/dIrr galaxies with known integrated colours (B −V ),(V −R ),or (B −R )(from papers by Ronnback &Bergvall 1994,McGaugh &Bothun 1994,de Blok et al.1995,van Zee et al.1997,O’Neil et al.1997,van Zee et al.2001,and Burkholder et al.2001)have such blue colours.Only one of the 65dIrr galaxies studied by Makarova et al.(1998),Makarova &Karachentsev (1998),and Makarova (1999)appeared that blue;Makarova et al.(1998)noted that this particular LSBG (UGCA 292)has several blue stellar complexes,in which van Zee (2000)detected strong line emission,indicating young starbursts.Thus,the unusual colours of SAO 0822+3545could be due to its recent enhanced SF.To estimate the age of its stellar population,we can compare its (B −V )0totand (V −R )0tot colours with model values.Unfortunately,due to the age-metallicity degeneracy,similar colours cancorrespond to very different ages.Therefore some a priori information on galaxy metallicity is necessary to disen-tangle the degeneracy.This can be obtained from the dIrr galaxy metallicity–luminosity relation (Skillman et al.1989;Pilyugin 2001).For SAO 0822+3545it predicts Z ∼1/20Z ⊙.In fact,for LSB galaxies this relation likelygoes significantly below (e.g.,Kunth &¨Ostlin 2000)thatfrom Skillman et al.,so 1/20Z ⊙is probably the upper limit for the metallicity of SAO 0822+3545.parison of observed and model parametersTo get some insight on the evolution status of SAO 0822+3545,we compared its observed colours and EW (H α)with model predictions.For colours we used results derived from PEGASE.2models (Fioc &Rocca-Volmerange 1997,2000).We also used these models to estimate the mass of the stellar population.We calculated spectral energy distributions (SEDs)for instantaneous SF bursts with Z =1/20and 1/50Z ⊙,as well as the time be-havior of B ,V ,R luminosities and the respective colour tracks.In Fig.8,we show BV R colour tracks for instan-taneous SF bursts with Z =1/20and 1/50Z ⊙,using solid and dotted lines,respectively,assuming a Salpeter IMF with M low =0.1M ⊙,M up =120M ⊙.The track for con-tinuous SF with constant SFR (Z =1/20Z ⊙)and the same IMF is shown by dashed line.SAO 0822+3545ex-。

星星之火可以燎燃英语作文Stars are often seen as distant and unreachable, shining brightly in the night sky. However, the phrase "A single spark can set a prairie on fire" reminds us that even the smallest actions can have a great impact. Just as a spark can ignite a whole prairie, a small idea or action can have the power to inspire change and create a bigger movement.Throughout history, we have seen countless examples of how a small act or idea has led to significant change. Take the example of Rosa Parks, an African American woman who refused to give up her seat to a white man on a bus in Montgomery, Alabama in 1955. Her small act of defiance sparked the Montgomery Bus Boycott, a pivotal moment in the Civil Rights Movement that eventually led to the desegregation of public transportation in the United States.Another example is the case of Malala Yousafzai, a young Pakistani girl who was shot by the Taliban for speaking out about girls' education. Despite facing grave danger, Malala continued to advocate for the rights of girls to receive an education. Her bravery and determination inspired a global movement and earned her the Nobel Peace Prize.These examples show us that even in the face of adversity, a single spark can ignite a fire of change. It only takes one person to stand up and take action to inspire others to do the same. By standing up for what we believe in and taking action, we have the power to make a difference and create a better world for future generations.In our daily lives, we may not face the same challenges as Rosa Parks or Malala Yousafzai, but we can still make a difference in our communities and the world around us. Whether it's volunteering at a local charity, advocating for environmental conservation, or standing up against injustice, every small action counts.As the saying goes, "Be the change you wish to see in the world." By being a spark of inspiration and taking action, we can set off a chain reaction that leads to positive change. So let's harness the power of that spark within us and let our light shine bright, igniting a fire of hope, compassion, and progress in the world. Remember, a single spark can set a prairie on fire.。

2022考研英语阅读天体化学Astrochemistry天体化学The great test tube in the sky空中的大试管Space is one big chemistry set宇宙是一个很大的化学装置MOST people think of the empty space between the stars as being, well, empty.大多数人们认为星星之间就是空无一物，但事实并非如此。

But it is not. It is actually filled with gas.实际上有气体弥散其中。

Admittedly, at an average density of 100-1,000 molecules per cubic centimetre, it is apretty thin gas.诚然，分子平均密度102-103/cm3的气体特别淡薄。

But space is big, so altogether there is quite a lot of it.不过由于空间很宽阔，气体分子总体数量是可观的。

Most of it, about 92%, is hydrogen.大部分的气体是氢，另外8%是惰性气体氦。

A further 8% is helium, which is chemically inert.还有一小部分由氧、碳、氮等其他元素构成的分子。

But a tiny fractionless than one-tenth of a percentconsists of molecules with otherelements, such as oxygen, carbon and nitrogen, in them. Though these other elements are amere soupon of the interstellar soup, they do give it real flavour.虽然这些元素仅仅是星际浓汤稍微的调料，但它们的确增加了汤的味道。

a r X i v :a s t r o -p h /9905359v 1 27 M a y 1999THE CHEMICAL EVOLUTION OF GALAXIES BYSUCCESSIVE STARBURSTST.Contini 1,R.Coziol 2,S.Consid`e re 3,E.Davoust 4,&R.E.Carlos Reyes 51European Southern Observatory,Garching bei M¨u nchen,Germany 2Osservatorio Astronomico di Brera,Milano,Italy 3Observatoire de Besanc ¸on,Besanc ¸on,France 4Observatoire Midi-Pyr´e n´e es,Toulouse,France 5Seminario Permanente de Astronom´ıa y Ciencas Espaciales,L´ıma,Per´u Abstract We propose an evolutionary scenario by successive bursts of star formation to reproduce the chemical properties of massive nearby Starburst Nucleus Galaxies (SBNGs).The N/O abundance ratios in SBNGs are ∼0.2dex higher than in normal H II regions observed in the disks of late–type spirals.The variation of the N/O ratio as a function of metallicity follows a primary +secondary relation,but the increase of nitrogen does not appear as a continuous process.Assuming that nitrogen is produced by intermediate-mass stars,we show that our observations are consistent with a model where the bulk of nitrogen in SBNGs was formed during past sequences of bursts of star formation which probably started 2or 3Gyrs in the past.1Introduction Recent observations obtained with the Hubble Space Telescope have made clear the urgency of un-derstanding the nature of the starburst phenomenon.Drastic and rapid changes of the population of galaxies have been observed over a short period of time and at a surprisingly recent epoch ([27],[14]).These observations seem to imply that most galaxies formed between redshifts of 1and 2([19])and support the hierarchical formation of galaxies paradigm.According to this theory,massive galaxies form by successive mergers of smaller mass and gas rich components.If each of these mergers trig-gers a burst of star formation ([26]),then,consequently,the galaxies form and evolve by a succession of bursts.Is this what we observe in present-day starburst galaxies?The subsequent discovery of forming galaxies at high redshifts with spectral characteristics in the UV similar to those of nearby starbursts ([23],[24])supports such an interpretation.That many nearby SBNGs could be the remnants of merging galaxies is already suggested by sev-eral observations ([17],[7],[1]).It has also been shown that i)SBNGs are chemically less evolved than normal galaxies with similar morphologies and comparable luminosities ([8]),ii)they are predom-inantly early–type spirals ([9],[10])and iii)they follow a luminosity–metallicity relation similar to that of elliptical galaxies ([11]).The SBNGs also have another intriguing property which makes them similar to star-forming galaxies at high redshifts.In their analysis of the properties of the Lyman-break galaxies,[23]concluded that the star formation rate in these galaxies was probably constantover the last Gyr.In the case of SBNGs,it has been demonstrated that multiple bursts of star forma-tion over a few Gyr period produce nearly constant star formation rates in these galaxies(,[6],[13]). But are these sequences of bursts the consequence of multiple merger events?In order to gain new insights on the nature and origin of the nearby SBNGs,we have embarked in a new project to establish a more complete picture of their chemical evolution.A new method has recently been devised for estimating nitrogen abundances in metal-rich galaxies([25]).We have taken advantage of this important advance to determine the abundance of nitrogen in SBNGs and compare it with the values observed in normal spirals.2The abundance of nitrogen in SBNGsOur sample of SBNGs was composed originally of208H II regions observed along the bars of75 Markarian barred galaxies(see[4],[5],[3]for details).From this sample,we rejected48H II regions because of their ambiguous classification using three spectroscopic diagnostic diagrams.The same criterion was used by[30]to build their sample of83FIR-bright SBNGs.After verifying that they have similar spectroscopic characteristics,we merged the two samples together.The detailed analysis can be found in[12].In SBNGs,nitrogen appears overabundant as compared to“normal”disk H II regions,with a relative abundance N/O which is∼0.2dex higher([12]).The range of N/O values found in SBNGs is comparable to that observed in the bulges of normal early-type spiral galaxies([25],[29]).On this matter,our observations are consistent with the recent discovery made by[25],who showed that H II regions in early-type spirals have slightly higher N/O ratios than H II regions in late-type spirals.In normal galaxies,samples of H II regions are preferentially found in late-type spirals where they are generally more numerous and luminous than in early-type galaxies.The SBNGs,on the other hand, are more numerous among early-type spirals([11]),explaining the observed higher abundance ratio in this sample.We conclude that our measurements of the nitrogen abundance in SBNGs are consistent with the chemical evolution of early-type spiral galaxies.This suggests that what we see could be the main production of nitrogen in the bulges of these galaxies.3An evolution by successive starburstsExamining how the abundance of nitrogen varies with the increase of oxygen,wefind that,contrary to normal disk H II regions,the SBNGs do not follow the secondary relation(see Fig.1a).A linear fit yields(with a correlation coefficient of76%)log(N/O)=0.55log(O/H)+0.8,which is consis-tent with a mixture of primary+secondary mode of production of nitrogen.But the increase of the N/O ratio with metallicity does not seem to follow a continuous process.The N/O ratio rises sharply by about0.3dex at an oxygen abundance of∼−3.4and stays almost constant in the range −3.4<log(O/H)<−2.9.In Figure1a,we show schematically how a sequence of bursts could explain our observations. Our scenario is based on the analytical model presented in[15].We assume that SBNGs begin their chemical evolution with N/O and O/H ratios typical of H II galaxies.Massive stars are responsible for the increase in oxygen,while nitrogen is only the product of intermediate-mass stars([28]).During thefirst burst,the rapid evolution of massive stars increases O/H and decreases N/O ([15],[22]).Then,after∼0.4Gyr,the evolution of intermediate–mass stars increases only N/O. Models of sequential bursts usually predict that successive bursts will have decreasing intensities ([16],[18]).A second burst,therefore,will produce a slightly lower increase of O/H.The decrease in N/O during oxygen enrichment(the slope of the vector)will also be smaller as it becomes more and more difficult to lower this ratio when the oxygen abundance increases([15]).Again,0.4Gyr after-4.4-4.0-3.6-3.2-2.8Log(O/H)-1.6-1.4-1.2-1.0-0.8-0.6L o g (N /O )-0.40.00.40.81.2∆(Ν/Ο)Log(O/H)-0.40.00.40.81.2∆(Ν/Ο)Figure 1:a)Schematic representation of the process of production of nitrogen in SBNGs by a sequence of bursts.The dispersion is caused by different initial intensities or different ages of the bursts (represented by only three different vector sums in this figure).Deviation of the observed nitrogen abundance from the secondary relation (∆(N/O))vs.oxygen abundance:b)in the SBNGS,and c)in normal H II regions.Note how the behavior becomes more starburst-like for normal galaxies with low metallicities.the beginning of the second burst,N/O will increase,but with an amplitude relatively smaller than in the first burst.If we increase the number of bursts and assume that successive bursts get weaker and weaker,the sum of the vectors should converge towards a line whose slope represents the mean increase of O/H and N/O in time.This slope may resemble the secondary relation.Indeed,it is inter-esting to note that,according to this scenario,a constant star formation is similar to an infinite sum of very low-intensity bursts of star formation,which is also consistent with the behavior of normal disk H II regions.The above model predicts that the deviation of the observed N/O ratio from the secondary relation (∆(N/O))will decrease with the age of starburst galaxies,or,equivalently,with their increase in metallicity.In Figure 1b,we see that this prediction is satisfied in the SBNGs.The fact that the deviation in Figure 1b is mostly positive could be explained by the different durations of the chemical evolutionary phases.Because massive stars have very short lifetimes,the oxygen enrichment phase is almost instantaneous,and O/H rapidly reaches a maximum (the tip of each horizontal vector in Figure 1a).The lifetime of the stars producing nitrogen,on the other hand,spans a much larger range of values.The nitrogen enrichment probably increases rapidly at the beginning,but extends over a longer period of time,as lower and lower-mass stars evolve.As a result,the top of each vertical vector in Figure 1a is always much more populated,this phase representing a sort of natural stable mode in the starburst’s evolution.According to the model of [2],the main phase of production of nitrogen in a burst should occur between 0.4and 1.6Gyrs after its beginning (this implies the evolution of stars from 8to 3M ⊙).Considering nearly constant star formation rates over the last 2–3Gyr ([6]),and assuming a median age of 1Gyr for one burst,it seems therefore that 2or 3bursts (or more if the bursts have shorter durations)are necessary to produce a sufficient number of co-evolved intermediate-mass stars needed to produce in turn the observed abundance of nitrogen.This would then push the origin of the main bursts 2to 3Gyrs in the past.4ConclusionThe time scales deduced above for the origin of the bursts in SBNGs are much longer than those predicted by interacting-merging galaxy models([20],[21]for example).It is not clear,therefore, what internal/external phenomenon could allow SBNGs to form stars over such a long period of time. In the literature,we know of only two models which predict sequences of bursts of star formation. The“stochastic self propagation of star formation”theory([16],[18])and the“hierarchical formation of galaxies”theory([26]).It is generally accepted that the Lyman-break galaxies are the progenitors of present-day normal massive galaxies([23]).The fact that the SBNGs show similar characteristics to those of these galax-ies suggests,therefore,that they may be nearby examples of galaxies still in formation.The SBNGs, consequently,would not be a peculiar phase in the evolution of galaxies,but the result of a process which was much more common in the past of the Universe.This process could be the hierarchical formation of galaxies.References[1]Barth,C.S.,Coziol,R.,Demers,S.,1995,MNRAS276,1224[2]Charlot,S.,Bruzual,A.G.,1991,Astrophys.J.367,126[3]Consid`e re,S.,Contini,T.,Davoust,E.,Coziol,R.,1999,in preparation[4]Contini,T.1996,Ph.D.Thesis,Universit´e Paul Sabatier,Toulouse,France[5]Contini,T.,Consid`e re,S.,Davoust,E.1998,Astr.Astrophys.Suppl.Ser.130,285[6]Coziol,R.,1996,Astr.Astrophys.309,345[7]Coziol,R.,Barth,C.S.,Demers S.1995,MNRAS276,2245[8]Coziol,R.,Contini,T.,Davoust E.,Consid`e re S.1997a,Astrophys.J.481,L67[9]Coziol,R.,Demers,S.,Barneoud R.,Pe˜n a M.,1997b,Astron.J.113,1548[10]Coziol,R.,Contini,T.,et al.,1998a,in“Abundance Profiles:Diagnostic Tools for Galaxy History”,Eds.D.Friedli et al.,ASP Conf.Ser.V ol.147,p.219[11]Coziol,R.,Torres,C.A.O.,et al.,1998b,Astrophys.J.Suppl.Ser.119,239[12]Coziol,R.,Carlos-Reyes,R.E.,Consid`e re,S.,et al.,1999,Astr.Astrophys.345,733[13]Doyon,R.,Coziol,R.,Demers,S.,1999,Astrophys.J.submitted,[14]Driver,S.P.,Fernandez-Soto,A.,Couch,W.J.,et al.,1998,Astrophys.J.496,93[15]Garnett,D.R.1990,Astrophys.J.363,142[16]Gerola,H.,Seiden,P.E.,Schulman,L.S.,1980,Astrophys.J.242,517[17]Keel,W.C.,van Soest,E.T.M.,1992,Astr.Astrophys.94,553[18]Kr¨u gel,E.,Tutukov,A.V.1993,Astr.Astrophys.275,416[19]Madau,P.,Pozzetti,L.,Dickinson,M.,1998,Astrophys.J.498,106[20]Mihos,J.C.,Hernquist,L.1994,Astrophys.J.425,L13[21]Mihos,J.C.,Hernquist,L.1996,Astrophys.J.464,641[22]Olofsson,K.1995,Astr.Astrophys.293,652[23]Steidel,C.C.,Giavalisco,M.,Pettini,M.,et al.,1996,Astrophys.J.462,L17[24]Steidel,C.C.,Adelberger,K.L.,et al.,1999,Astrophys.J.in press,(astro-ph/9811399)[25]Thurston,T.R.,Edmunds,M.G.,Henry,R.B.C.,1996,MNRAS283,990[26]Tinsley B.M.,Larson R.B.1979,MNRAS186,503[27]van den Bergh,S.,Abraham,R.G.,Ellis,R.S.,et al.,1996,Astron.J.112,359[28]van den Hoek,B.,Groenewegen,M.A.T.1997,Astr.Astrophys.Suppl.Ser.123,305[29]van Zee,L.,Salzer,J.J.,Haynes,M.P.,1998,Astrophys.J.497,L1[30]Veilleux,S.,Kim,D.-C.,Sanders,D.B.,et al.,1995,Astrophys.J.Suppl.Ser.98,171。

The Role of Electrochemistry inBatteries电化学在电池中的角色电池是一种将化学能转换成电能的装置，现在已经成为日常生活中不可或缺的一部分。

从手电筒到汽车，从移动电话到笔记本电脑，电池所有的形态和大小都被广泛使用。

电化学是研究电化学反应的学科。

在电池中，电化学反应是将化学能转换为电能的过程，同时从电池中提取电能时，电能又转化回化学能。

因此，电化学在电池中起着关键的作用，并直接影响电池的性能。

电化学作用于电池的两种形式：脱电子和氧化还原反应。

脱电子是指铅酸电池中的铅板通电后，铅会释放出电子形成氧化铅。

当电子回流时，铅再次得到了它的电子，变成了还原铅。

这就是一个典型的氧化还原反应例子。

在这个过程中，电子会在负极（即铅板）和正极（即铅二氧化物）之间移动，产生电流。

同时，铅板和铅二氧化物之间的化学反应产生了热量，可以驱动电动机等外部设备的工作。

因此，电化学反应不仅是电池产生电能的基础，还为其他设备的工作提供了能量。

除了脱电子和氧化还原反应，电化学反应还可以在电极之间和电极和溶液之间发生。

电极是电池中的两个重要部分之一，一个极是正极，另一个极是负极。

当电池连接电路时，这两个极就会产生电势差，并开始工作。

在电解液中，化学物质会使电解液中的离子产生电子或接受电子，这就是电化学反应。

在锂离子电池中，锂离子从一个电极移动到另一个电极，而这个过程就是电化学反应中离子交换的结果。

电化学反应还影响电池的寿命和可靠性。

例如，在锂离子电池中，锂在电解质和电极之间不断来回移动，从而使电极的材料发生变化，从而缩短了电池的寿命。

此外，锂离子电池还可能会发生“过充”或“过放”的问题，这些问题都是由于电化学反应的变化而导致的。

电化学反应对电池性能的影响并不只限于锂离子电池，在其他类型的电池中也同样重要。

除此之外，电化学反应还有助于提高电池的效率和性能。

例如，在锂离子电池中，电解质可以改变锂离子的传输性质，从而提高电池的性能。

阐述爱丽丝鲍尔的科学精神英语作文80词全文共3篇示例，供读者参考篇1Alice Ball was a remarkable scientist whose pioneering work in the field of chemistry had a significant impact on the treatment of leprosy. Born in 1892, she displayed a keen interest in science from a young age and went on to become the first African American woman to graduate with a master's degree in chemistry from the University of Hawaii.Ball's most significant contribution to the field of science was the development of the "Ball Method," a successful treatment for leprosy using chaulmoogra oil. Prior to her discovery, the oil was considered ineffective due to its insoluble nature. However, Ball's innovative technique involved isolating the active components of the oil and creating a more soluble injectable form, which greatly improved its efficacy in treating the disease.Ball's scientific breakthrough had a profound impact on the lives of countless individuals suffering from leprosy, providing them with a more effective and accessible treatment option. Her pioneering spirit and dedication to her research continue toinspire future generations of scientists and serve as a testament to the power of perseverance and innovation in the field of science. Alice Ball's legacy lives on through her groundbreaking work and serves as a reminder of the transformative potential of scientific discovery.篇2Alice Ball was a chemist known for her groundbreaking work in the field of medicine. Her research on the treatment of leprosy led to the development of the first effective treatment for the disease, known as the "Ball Method."Ball's scientific spirit was evident from a young age. Born in 1892, she showed an early interest in chemistry and medicine. She went on to study chemistry at the University of Washington, where she excelled in her studies and received a bachelor's degree in pharmaceutical chemistry in 1912.After completing her studies, Ball began working at the College of Hawaii (now known as the University of Hawaii) as a research assistant. It was here that she began her research on the treatment of leprosy, a disease that had long been misunderstood and stigmatized.Through her research, Ball discovered a way to isolate the active compound in chaulmoogra oil, a traditional treatment for leprosy. She then developed a method to make the compound soluble in oil, making it easier to administer as an injection. This innovation revolutionized the treatment of leprosy and saved countless lives.Ball's scientific contributions were cut short when she tragically passed away at the young age of 24. However, her legacy lives on through the lives she saved and the impact she made on the field of medicine.Alice Ball's story is a testament to the power of the scientific spirit. Through her dedication, perseverance, and innovative thinking, she was able to make a significant impact on the world of medicine. Her work serves as an inspiration to future generations of scientists, reminding us of the importance of pushing the boundaries of knowledge and striving for breakthroughs that can change the world.篇3Alice Ball was a pioneer in the field of chemistry, whose scientific spirit and dedication have left a lasting impact on the world of medicine. Born in 1892, Ball overcame numerousobstacles to pursue her passion for chemistry and became the first African American woman to receive a master's degree in chemistry from the University of Hawaii.Ball's groundbreaking work in developing a treatment for leprosy, known as the "Ball Method," revolutionized the treatment of the disease. By isolating the active compound in chaulmoogra oil and creating an injectable form of the medicine, Ball significantly improved the lives of countless individuals suffering from leprosy.Ball's scientific approach and meticulous research have inspired future generations of chemists and medical researchers. Her dedication to finding innovative solutions to complex problems serves as a testament to the power of perseverance and passion in the pursuit of scientific discovery.In conclusion, Alice Ball's legacy as a pioneering chemist and medical researcher continues to inspire individuals around the world to push the boundaries of scientific knowledge and make a lasting impact on society. Her innovative approach to tackling challenges and her unwavering dedication to her work serve as a beacon of inspiration for future generations of scientists.。

药剂英文试题及答案高中一、选择题（每题2分，共20分）1. What is the primary function of a pharmaceutical excipient?A. To enhance the therapeutic effect of the drugB. To improve the stability of the drugC. To act as a carrier for the drugD. To provide a specific color to the drugAnswer: C. To act as a carrier for the drug2. Which of the following is not a method of drug administration?A. OralB. IntravenousC. TopicalD. ElectrolysisAnswer: D. Electrolysis3. What is the term used to describe the process of a drug being absorbed into the bloodstream after administration?A. DistributionB. AbsorptionC. MetabolismD. ExcretionAnswer: B. Absorption4. Which of the following is a bioequivalence study?A. Study of drug interactionsB. Study of drug absorptionC. Comparison of the rate and extent to which the active ingredient becomes available after two different administration formsD. Study of drug stabilityAnswer: C. Comparison of the rate and extent to which the active ingredient becomes available after two different administration forms5. What is the main purpose of a controlled-release drug formulation?A. To reduce the frequency of administrationB. To increase the drug's solubilityC. To enhance the drug's tasteD. To decrease the drug's side effectsAnswer: A. To reduce the frequency of administration二、填空题（每题2分，共20分）6. The ________ of a drug refers to its ability to reach the systemic circulation after administration.Answer: Bioavailability7. A ________ is a type of drug delivery system that allows for the controlled release of a drug.Answer: Transdermal patch8. The ________ is the study of the physical and chemical properties of drugs.Answer: Pharmaceutical chemistry9. In pharmaceuticals, ________ is the process of turning a liquid into a fine spray.Answer: Nebulization10. The ________ is a technique used to determine the purity and composition of a substance.Answer: Chromatography三、简答题（每题10分，共40分）11. Explain the importance of drug stability in pharmaceutical formulations.Answer: Drug stability is crucial in pharmaceutical formulations as it ensures that the drug maintains its potency, purity, and safety over time. Unstable drugs can degrade, leading to reduced efficacy or the formation of harmful by-products.12. Describe the role of a pharmacist in the healthcare system.Answer: A pharmacist plays a pivotal role in the healthcare system by preparing and dispensing medications, providing drug information, monitoring patient medication therapy for safety and efficacy, and offering advice on thesafe use of medications.13. What are the factors that influence the bioavailability of a drug?Answer: Factors influencing drug bioavailability include the drug's chemical properties, the formulation, the route of administration, the presence of food, and the patient's physiological state.14. Discuss the concept of drug-drug interactions and their clinical significance.Answer: Drug-drug interactions occur when two or more drugs affect each other's action or efficacy. These interactions can lead to increased side effects, reduced therapeutic effect, or even toxicity, which is why understanding and managing them is of clinical significance.四、论述题（共20分）15. Discuss the ethical considerations in the development and use of new pharmaceuticals.Answer: Ethical considerations in the development and use of new pharmaceuticals include ensuring patient safety, maintaining transparency in clinical trials, avoiding conflicts of interest, respecting patient autonomy, and ensuring equitable access to medications, especially for vulnerable populations.结束语：通过这份药剂英文试题及答案，我们希望能够帮助高中学生更好地掌握药剂学的基础知识，并培养他们对药物研发和应用的深入理解。

小学下册英语能力测评(含答案)英语试题一、综合题(本题有50小题，每小题1分，共100分.每小题不选、错误，均不给分)1 What do we call a young tiger?A. CubB. PuppyC. KittenD. Calf2 He is very _____ (热情) about his work.3 The __________ is the layer of the earth we live on.4 She likes to wear ___. (jewelry)5 We will go to the ___. (concert)6 The _______ (The Renaissance) led to advancements in arts and sciences.7 The cow gives us fresh _________. (牛奶)8 The symbol for copper is _____.9 The process of respiration takes place in the _______ of cells.10 What type of animal is a frog?A. MammalB. ReptileC. AmphibianD. Bird11 Which season comes after spring?B. SummerC. AutumnD. Fall12 The chemical formula for potassium cyanide is __________.13 My mother is a _____ (教师) who loves kids.14 What do we call the frozen form of water?A. SteamB. IceC. RainD. Snow15 The _______ can change its shape with the seasons.16 The best part of school is __________. I enjoy learning new things and discovering my interests. My favorite project this year was __________.17 The chemical formula for sodium phosphate is ______.18 What is 5 x 5?a. 10b. 15c. 25d. 30答案:C19 The ______ (老虎) has stripes that help it blend in.20 A __________ is a region known for its cultural heritage.21 The chemical formula for beryllium oxide is ______.22 What is the main ingredient in bread?B. FlourC. RiceD. Salt23 habitat fragmentation) threatens many species. The ____24 What is the name of the famous scientist known for his work on the laws of thermodynamics?A. Rudolf ClausiusB. Lord KelvinC. James Clerk MaxwellD. Albert Einstein答案: A25 The ______ is an imaginary line around the Earth.26 Which holiday is celebrated with fireworks on New Year's Eve?A. ChristmasB. ThanksgivingC. DiwaliD. New Year27 The capital of Finland is ________ (芬兰的首都是________).28 The man is very ________.29 What do we call a young lion?A. CubB. KittenC. PupD. Foal30 The ancient Romans were known for their legal ________ (体系).31 Which of these is a mode of transportation?A. TrainB. ChairC. TableD. Lamp32 A catalyst speeds up a _______ without being consumed.33 What do you call a young chicken?A. CubB. ChickC. DucklingD. Gosling34 What is the name of the fairy tale character with long hair?A. CinderellaB. RapunzelC. Snow WhiteD. Belle35 The country of Norway is famous for its ________ (挪威以其________而闻名).36 What is the name of the fairy tale character who has very long hair?A. Snow WhiteB. CinderellaC. RapunzelD. Ariel答案:C37 Did you see the _____ (兔子) hopping around?38 A ____(community needs assessment) identifies gaps in services.39 What do you call the person who teaches in school?A. DoctorB. TeacherC. EngineerD. Chef40 Queen Elizabeth I ruled during the __________ period. (都铎王朝)41 I want to be a ______ (teacher) when I grow up.42 Many plants are important for _____ (生态平衡).43 The pizza has ___ (pepperoni) on it.44 What do we call the study of the properties of matter?A. ChemistryB. PhysicsC. BiologyD. Geology答案: A45 A reaction that occurs at low temperatures is called a ______ reaction.46 What is the capital of Iraq?A. BaghdadB. MosulC. BasraD. Erbil47 What do we call a small, fluffy animal that hops?A. DogB. CatD. Guinea pig48 Leaves collect ______ (阳光).49 What is the capital of Cyprus?A. NicosiaB. LimassolC. LarnacaD. Paphos答案:A. Nicosia50 My _______ (兔子) is very playful.51 My mom enjoys __________ (参加) family gatherings.52 The speed of sound is faster than the speed of ______.53 My dad works in an _____ building. (office)54 The _____ (森林) is home to many species of plants.55 An ion is an atom that has gained or lost _______.56 What do you call the study of the universe?A. AstronomyB. AstrologyC. PhysicsD. Geography答案: A57 We have a class pet, a ________ (仓鼠) named ________ (小华). It’s very ________ (可爱).58 What do you call a person who studies animals?A. ZoologistC. EcologistD. Ethologist答案: A59 The wind is ___ (strong/light).60 The ________ was a major turning point in the fight for freedom.61 I like to ______ stories about adventures. (read)62 What do you call the study of fungi?A. MycologyB. BotanyC. ZoologyD. Ecology答案:A63 What is the opposite of "strong"?A. WeakB. PowerfulC. MightyD. Robust64 My cousin is a ______. She enjoys painting landscapes.65 Which food is made from milk?A. BreadB. CheeseC. RiceD. Pasta66 I want to learn to ________ (制作手工艺).67 What do you call a person who studies the human brain?A. NeurologistB. PsychologistC. PsychiatristD. All of the above答案:D68 He is reading a ______ (story).69 Ancient Greece is often called the birthplace of _____.70 The ______ helps with the immune system.71 My cousin is a ______. She loves to write songs.72 My ___ (小狗) greets me at the door.73 The ________ (文化价值观) shape societies.74 The __________ is a famous area known for its cultural events.75 What is the main ingredient in ice cream?A. WaterB. MilkC. SugarD. Eggs76 The ancient Romans were renowned for their ________ and public works.77 What do we call a sweet drink made from fermented grapes?A. WineB. CiderC. MeadD. Ale78 Which month is the beginning of summer?B. JuneC. SeptemberD. December答案：B79 The process of changing from a solid to a liquid is called ______.80 Objects in motion tend to stay in ______.81 The capital of Luxembourg is __________.82 The doctor, ______ (医生), checks our health every year.83 The manatee is gentle and eats ______ (水草).84 What do we call the process of plants making food?A. PhotosynthesisB. RespirationC. DigestionD. Evaporation答案: A85 The rock cycle can take millions of ______ to complete.86 The _____ (窗户) is open.87 The _______ (小鸽子) returns to its home every evening.88 My mom loves to make ____ (lasagna) for dinner.89 What is the opposite of "happy"?A. SadB. JoyfulC. ExcitedD. Angry90 __________ are used in the production of rubber.91 A __________ can provide insights into natural disasters.92 The __________ is important for human habitation and agriculture.93 A trench is a deep ______ in the ocean floor.94 A whale is the largest _______ in the ocean.95 What do we use to see at night?A. SunB. LampC. StarsD. Moon96 A chemical reaction can involve the absorption of _____.97 The window is _______ (open) wide.98 The teacher is _____ (kind/mean) to us.99 What is the name of the famous ancient site in Egypt?A. Great PyramidB. ColosseumC. Taj MahalD. Stonehenge答案: A100 My sister enjoys _______ (画画)。

生物学英语复试题及答案一、选择题1. Which of the following is not a characteristic of living organisms?A. Growth and developmentB. ReproductionC. ResponsivenessD. Inertia2. What is the basic unit of life?A. CellB. TissueC. OrganD. Organ system3. What is the process of photosynthesis?A. The conversion of light energy into chemical energyB. The conversion of chemical energy into light energyC. The conversion of heat energy into chemical energyD. The conversion of chemical energy into heat energy4. What is the primary function of chlorophyll in plants?A. To absorb light energyB. To store chemical energyC. To release oxygenD. To produce water5. What is the main component of the cell membrane?A. ProteinsB. LipidsC. CarbohydratesD. Nucleic acids二、填空题6. The genetic material of all living organisms is either__________ or __________.7. The process by which organisms adapt to their environment is called __________.8. In eukaryotic cells, the organelles that are responsible for energy production are __________.9. The basic structural and functional unit of a protein is the __________.10. The process of an organism developing from a fertilized egg into a mature individual is known as __________.三、简答题11. Explain the role of DNA in the cell.12. Describe the process of cellular respiration.13. What are the main differences between prokaryotic and eukaryotic cells?四、论述题14. Discuss the importance of biodiversity and the threats itfaces.五、翻译题15. Translate the following sentence into English:“细胞分裂是生物体生长和发育的基本过程。