Both density gradient centrifugation and gel electrophoresis have been reported to allow high throughput separation of metallic from semiconducting single-walled carbon nanotubes(SWNTs)when using aqueous sodium dodecy...Both density gradient centrifugation and gel electrophoresis have been reported to allow high throughput separation of metallic from semiconducting single-walled carbon nanotubes(SWNTs)when using aqueous sodium dodecyl sulphate(SDS)suspensions.We show here that both methods rely on an initial dispersion-by-sonication step,which is already selective with respect to electronic structure type.The corresponding aqueous SDS“starting”suspensions obtained after sonication and purifi cation by simple centrifugation(70,000 g,1 h)contain semiconducting SWNTs primarily in the form of small bundles whereas metallic SWNTs are predominantly suspended as individual tubes.Density gradient centrifugation then separates the bundles from the individual tubes on the basis of differences in their overall buoyant densities.Gel electrophoresis separates the longer bundles from the shorter individual tubes on the basis of their different mobilities.We also demonstrate that such starting suspensions can be fractionated according to electronic structure type by even simpler techniques such as size exclusion chromatography or gel fi ltration,thus opening the way for simple scale-up.展开更多
This study presents a design strategy to enhance the high-temperature creep resistance of Ni-based superalloys.This strategy focuses on two principles:(1)minimizing the dimensions ofγ/γ′interfaces andγchannels by ...This study presents a design strategy to enhance the high-temperature creep resistance of Ni-based superalloys.This strategy focuses on two principles:(1)minimizing the dimensions ofγ/γ′interfaces andγchannels by reducing the size of theγ′phase;(2)key alloy composition control to strengthen the heterostructureγ/γ′interfaces.This strategy proved very effective by the designed three superalloys'prolonged creep lives.An alloy exhibits ultra-long creep life by 388 h at 1100°C/137 MPa,which runs at the highest level among those alloys without Ru addition.With Ru addition,an alloy that lasted for 748 h with a creep strain of~6%at 1110°C/137 MPa is developed.This study provides a new route of high-temperature creep lives through heterostructure interfacial design with size effects and key alloying elements.展开更多
Although an accurate evaluation of the distribution of ultrafine particulate matter in air is of utmost significance to public health,the usually used PM2.5 index fails to provide size distribution information.Here we...Although an accurate evaluation of the distribution of ultrafine particulate matter in air is of utmost significance to public health,the usually used PM2.5 index fails to provide size distribution information.Here we demonstrate a low-profile and cavity-free size spectrometer for probing fine and ultrafine particulate matter by using the enhanced particle-perturbed scattering in strong optical evanescent fields of a nanofiber array.The unprecedented size resolution reaches 10 nm for detecting single 100-nm-diameter nanoparticles by employing uniform nanofibers and controlling the polarizations of the probe light.This size spectrometry was tested and used to retrieve the size distribution of particulate matter in the air of Beijing,yielding mass concentrations of nanoparticles,as a secondary exercise,consistent with the officially released data.This nanofiber-array probe shows potential for the full monitoring of air pollution and for studying early-stage haze evolution and can be further extended to explore nanoparticle interactions.展开更多
In the past decade,ferroelectric materials have been intensively explored as promising photocatalysts.An intriguing ability of ferroelectrics is to directly sperate the photogenerated electrons and holes,which is beli...In the past decade,ferroelectric materials have been intensively explored as promising photocatalysts.An intriguing ability of ferroelectrics is to directly sperate the photogenerated electrons and holes,which is believed to arise from a spontaneous polarization.Understanding how polarization affects the photocatalytic performance is vital to design high-efficiency photocatalysts.In this work,we report a size effect of ferroelectric polarization on regulating the photocatalytic overall water splitting of SrTiO_(3)/PbTiO_(3)nanoplate heterostructures for the first time.This was realized hydrothermally by controlling the thickness and thus spontaneous polarization strength of single-crystal and single-domain PbTiO_(3)nanoplates,which served as the substrate for selective heteroepitaxial growth of SrTiO_(3).An enhancement of 22 times in the photocatalytic overall water splitting performance of the heterostructures has been achieved when the average thickness of the nanoplate increases from 30 to 107 nm.A combined experimental investigation revealed that the incompletely compensated depolarization filed is the dominated driving force for the photogenerated carrier separation within heterostructures,and its increase with the thickness of the nanoplates accounts for the enhancement of photocatalytic activity.Moreover,the concentration of oxygen vacancies for negative polarization compensation has been found to grow as the thickness of the nanoplates increases,which promotes oxygen evolution reaction and reduces the stoichiometric ratio of H_(2)/O_(2).These findings may provide the opportunity to design and develop high-efficiency ferroelectric photocatalysts.展开更多
In order to study the indentation size effect(ISE)of germanium single crystals,nano-indentation experiments were carried out on the(100),(110)and(111)plane-orientated germanium single crystals.The true hardness of eac...In order to study the indentation size effect(ISE)of germanium single crystals,nano-indentation experiments were carried out on the(100),(110)and(111)plane-orientated germanium single crystals.The true hardness of each crystal plane of germanium single crystals was calculated based on the Meyer equation,proportional sample resistance(PSR)model and Nix-Gao model,and the indentation size effect(ISE)factor of each crystal plane was calculated.Results show that,the germanium single crystals experience elastic deformation,plastic deformation and brittle fracture during the loading process,and the three crystal planes all show obvious ISE phenomenon.All three models can effectively describe the ISE of germanium single crystals,and the calculated value of Nix-Gao model is the most accurate.Compared with the other two crystal planes,Ge(110)has the highest size effect factor m and the highest hardness,which indicates that Ge(110)has the worst plasticity.展开更多
Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-h...Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability.展开更多
Single particle-inductively coupled plasma mass spectrometry (SP-ICP-MS) is a powerful tool for size-characterization of metal-containing nanoparticles (MCNs) at environmentally relevant concentrations,however,coexist...Single particle-inductively coupled plasma mass spectrometry (SP-ICP-MS) is a powerful tool for size-characterization of metal-containing nanoparticles (MCNs) at environmentally relevant concentrations,however,coexisting dissolved metal ions greatly interfere with the accuracy of particle size analysis.The purpose of this study is to develop an online technique that couples hollow fiber ultrafiltration (HFUF) with SP-ICP-MS to improve the accuracy and size detection limit of MCNs by removing metal ions from suspensions of MCNs.Through systematic optimization of conditions including the type and concentration of surfactant and complexing agent,carrier pH,and ion cleaning time,HFUF completely removes metal ions but retains the MCNs in suspension.The optimal conditions include using a mixture of 0.05 vol.%FL-70 and 0.5 mmol/L Na2S2O_(3)(pH=8.0) as the carrier and 4 min as the ion cleaning time.At these conditions,HFUF-SP-ICP-MS accurately determines the sizes of MCNs,and the results agree with the size distribution determined by transmission electron microscopy,even when metal ions also are present in the sample.In addition,reducing the ionic background through HFUF also lowers the particle size detection limit with SP-ICP-MS (e.g.,from 28.3 to 14.2 nm for gold nanoparticles).This size-based ion-removal principle provided by HFUF is suitable for both cations (e.g.,Ag+) and anions (e.g.,AuCl_(4)^(-)) and thus has good versatility compared to ion exchange purification and promising prospects for the removal of salts and macromolecules before single particle analysis.展开更多
The excellent dislocation storage ability of bulk multi-principal element alloys(MPEAs)has been widely reported.To date,however,the underlying mechanisms of dislocation escape behavior in small-size facecentered cubic...The excellent dislocation storage ability of bulk multi-principal element alloys(MPEAs)has been widely reported.To date,however,the underlying mechanisms of dislocation escape behavior in small-size facecentered cubic(FCC)MPEAs have rarely been studied.Here,we quantitatively control the initial dislocation densities(-10^(15) m^(-2) and -10^(16) m^(-2))by large-scale molecular dynamics(MD)simulations and perform uniaxial compression simulations to compare the dislocation starvation behavior of CrCoNi with pure Cu single crystal pillars(SCPs).The analysis reveals that the CrCoNi SCPs with low initial dislocation density(-10^(15) m^(-2))can continuously accommodate mobile dislocations,and the critical dimension for dislocation starvation is about 30 nm.In particular,the CrCoNi SCPs with chemical short-range ordering(SRO)exhibit better dislocation storage and multiplication abilities than the random solid solution(RSS)samples even when the initial dislocation density is low.However,the presence of a large number of pre-existing dislocation locks governs the strong dislocation multiplication ability of the small-size RSS CrCoNi SCPs,in obvious contrast to the deformation of all pure Cu SCPs which is completely dominated by intermittent mobile dislocation starvation.Most importantly,we reveal the fundamental physics for the good dislocation storage of CrCoNi SCPs at small sizes from the perspective of chemical heterogeneity.The new phenomena reported in this work provide a unique atomic-scale perspective for understanding the microscopic physical origin of the mechanical behavior of MPEAs and the discovery of extremely slow dislocation escape behavior in small-scaled pillars,providing a reliable basis for the development of the dislocation starvation model.展开更多
The stress-strain behavior and copper are studied by the molecular dynamics incipient yield surface of nanoporous single crystal （MD） method. The problem is modeled by a periodic unit cell subject to multi-axial loa...The stress-strain behavior and copper are studied by the molecular dynamics incipient yield surface of nanoporous single crystal （MD） method. The problem is modeled by a periodic unit cell subject to multi-axial loading. The loading induced defect evolution is explored. The incipient yield surfaces are found to be tension-compression asymmetric. For a given void volume fraction, apparent size effects in the yield surface are predicted： the smaller behaves stronger. The evolution pattern of defects （i.e., dislocation and stacking faults） is insensitive to the model size and void volume fraction. However, it is loading path dependent. Squared prismatic dislocation loops dominate the incipient yielding under hydrostatic tension while stacking-faults are the primary defects for hydrostatic compression and uniaxial tension/compression.展开更多
A microfluidic device to control single crystallization on the micron scale has been developed. The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip. Th...A microfluidic device to control single crystallization on the micron scale has been developed. The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip. The mixed organic solvent was injected into the chip as the counter diffusion phase for crystallization forming. This device provides a liquid-liquid interface through which only one phase flows while the other stays at the fixed plot. Therefore, it is possible to control the position of crystallization on the fixed plot. We can control the size and the uniformity of single crystals from 5 to 50 μm in length by adjusting the relative factors, such as interface lifetime, breeds of the mix-organic solvents and injecting velocities. The longer interface lifetime and lower organic solvent injecting velocities can bring up larger and more asymmetric crystals, which nearly shows the same trend compared with the macroscopic crystallization. Finally, the effect of the surfactant on the crystallization in the microdevice was studied. By adding the surfactant into the liquid-liquid interface, smaller sizes of crystals can be obtained without changing the crystal configuration.展开更多
The erythropoietin receptor （EPOR） has shown to play an important role in fetal survival by promoting the maturation of red blood cells in many studies of uterine capacity and litter size in swine. In this study, we...The erythropoietin receptor （EPOR） has shown to play an important role in fetal survival by promoting the maturation of red blood cells in many studies of uterine capacity and litter size in swine. In this study, we screened the porcine EPOR gene for mutations and identified five single nucleotide polymorphisms （SNPs）： g.705G〉T in intron 1, g.2 373C〉T in intron 4, and g.2 882C〉T, g.3 035A〉G, and g.3 132A〉T in intron 6. We then genotyped 247 Beijing Black （BB） sows and compared the polymorphism data with the litter sizes of 1 375 parities among the sows. At first parity, there was no association of g.2 882C〉T and g.3 132A〉T with litter sizes. However, the CT sows in g.2 882C〉T had 2.13 higher total number born （TNB） （P〈0.01） and 1.81 higher number born alive （NBA） （P〈0.01） than the CC sows and the heterozygous sows in g.3 132A〉T had the highest litter size when compared to the two homozygotes for the later parities （P〈0.05）. In the g.3 035A〉G SNP, for the later parities, the TNB of the sows with the GG genotype was 3.81 higher （P〈0.01） and the NBA was 2.75 higher （P〈0.01） than that with the AA genotype but no difference at first parity. The G allele of the EPOR g.705G〉T SNP was associated with a greater litter size at both the first parity （P〈0.05） and later parities （P〈0.01）. Furthermore, we determined the allele frequencies for this SNP among five Chinese indigenous pig breeds （Erhualian, Laiwu Black, Meishan, Min, and Rongchang） and three western commercial pig breeds （Duroc, Landrace, and Large White）. The G allele of the EPOR g.705G〉T SNP was significantly more common in the more prolific Chinese breeds. These results indicated that the EPOR could be an important candidate gene for litter size and g.705G〉T can serve as a useful genetic marker for improving litter size in both first and later parities in swine.展开更多
基金by the Bundes-ministerium für Bildung und Forschung(BMBF)by the Deutsche Forschungsgemeinschaft(DFG).
文摘Both density gradient centrifugation and gel electrophoresis have been reported to allow high throughput separation of metallic from semiconducting single-walled carbon nanotubes(SWNTs)when using aqueous sodium dodecyl sulphate(SDS)suspensions.We show here that both methods rely on an initial dispersion-by-sonication step,which is already selective with respect to electronic structure type.The corresponding aqueous SDS“starting”suspensions obtained after sonication and purifi cation by simple centrifugation(70,000 g,1 h)contain semiconducting SWNTs primarily in the form of small bundles whereas metallic SWNTs are predominantly suspended as individual tubes.Density gradient centrifugation then separates the bundles from the individual tubes on the basis of differences in their overall buoyant densities.Gel electrophoresis separates the longer bundles from the shorter individual tubes on the basis of their different mobilities.We also demonstrate that such starting suspensions can be fractionated according to electronic structure type by even simpler techniques such as size exclusion chromatography or gel fi ltration,thus opening the way for simple scale-up.
基金supported by the National Key Research and Development Program of China(2021YFA1200201)the Natural Science Foundation of China(91860202,51988101,52171001,52071003 and 52001297)+3 种基金the R&D Program of Beijing Municipal Education Commission(KM202210005003)the Beijing Outstanding Young Scientists Projects(BJJWZYJH01201910005018)the Beijing Nova Program(Z211100002121170)the Overseas Expertise Introduction Project for Discipline Innovation(“111”project)(DB18015)
文摘This study presents a design strategy to enhance the high-temperature creep resistance of Ni-based superalloys.This strategy focuses on two principles:(1)minimizing the dimensions ofγ/γ′interfaces andγchannels by reducing the size of theγ′phase;(2)key alloy composition control to strengthen the heterostructureγ/γ′interfaces.This strategy proved very effective by the designed three superalloys'prolonged creep lives.An alloy exhibits ultra-long creep life by 388 h at 1100°C/137 MPa,which runs at the highest level among those alloys without Ru addition.With Ru addition,an alloy that lasted for 748 h with a creep strain of~6%at 1110°C/137 MPa is developed.This study provides a new route of high-temperature creep lives through heterostructure interfacial design with size effects and key alloying elements.
基金supported by the NSFC(Grant Nos.61435001,61611540346,11474011 and 11654003)the National Key R&D Program of China(Grant No.2016YFA0301302)supported by the China Postdoctoral Science Foundation(Grant No.2015M580909).
文摘Although an accurate evaluation of the distribution of ultrafine particulate matter in air is of utmost significance to public health,the usually used PM2.5 index fails to provide size distribution information.Here we demonstrate a low-profile and cavity-free size spectrometer for probing fine and ultrafine particulate matter by using the enhanced particle-perturbed scattering in strong optical evanescent fields of a nanofiber array.The unprecedented size resolution reaches 10 nm for detecting single 100-nm-diameter nanoparticles by employing uniform nanofibers and controlling the polarizations of the probe light.This size spectrometry was tested and used to retrieve the size distribution of particulate matter in the air of Beijing,yielding mass concentrations of nanoparticles,as a secondary exercise,consistent with the officially released data.This nanofiber-array probe shows potential for the full monitoring of air pollution and for studying early-stage haze evolution and can be further extended to explore nanoparticle interactions.
基金supported by the National Key R&D Program of China(No.2021YFA1500800)the National Natural Science Foundation of China(Nos.52425201,52272129,and 12125407)+2 种基金the Natural Science Foundation of Zhejiang Province,China(No.LR21E020004)the ShanxiZheda Institute of Advanced Materials and Chemical Engineering(No.2021SX-FR007)the Joint Funds of the National Natural Science Foundation of China(No.U21A2067).
文摘In the past decade,ferroelectric materials have been intensively explored as promising photocatalysts.An intriguing ability of ferroelectrics is to directly sperate the photogenerated electrons and holes,which is believed to arise from a spontaneous polarization.Understanding how polarization affects the photocatalytic performance is vital to design high-efficiency photocatalysts.In this work,we report a size effect of ferroelectric polarization on regulating the photocatalytic overall water splitting of SrTiO_(3)/PbTiO_(3)nanoplate heterostructures for the first time.This was realized hydrothermally by controlling the thickness and thus spontaneous polarization strength of single-crystal and single-domain PbTiO_(3)nanoplates,which served as the substrate for selective heteroepitaxial growth of SrTiO_(3).An enhancement of 22 times in the photocatalytic overall water splitting performance of the heterostructures has been achieved when the average thickness of the nanoplate increases from 30 to 107 nm.A combined experimental investigation revealed that the incompletely compensated depolarization filed is the dominated driving force for the photogenerated carrier separation within heterostructures,and its increase with the thickness of the nanoplates accounts for the enhancement of photocatalytic activity.Moreover,the concentration of oxygen vacancies for negative polarization compensation has been found to grow as the thickness of the nanoplates increases,which promotes oxygen evolution reaction and reduces the stoichiometric ratio of H_(2)/O_(2).These findings may provide the opportunity to design and develop high-efficiency ferroelectric photocatalysts.
基金Project(51765027)supported by the National Natural Science Foundation of China.
文摘In order to study the indentation size effect(ISE)of germanium single crystals,nano-indentation experiments were carried out on the(100),(110)and(111)plane-orientated germanium single crystals.The true hardness of each crystal plane of germanium single crystals was calculated based on the Meyer equation,proportional sample resistance(PSR)model and Nix-Gao model,and the indentation size effect(ISE)factor of each crystal plane was calculated.Results show that,the germanium single crystals experience elastic deformation,plastic deformation and brittle fracture during the loading process,and the three crystal planes all show obvious ISE phenomenon.All three models can effectively describe the ISE of germanium single crystals,and the calculated value of Nix-Gao model is the most accurate.Compared with the other two crystal planes,Ge(110)has the highest size effect factor m and the highest hardness,which indicates that Ge(110)has the worst plasticity.
基金The support from the National Natural Science Foundation of China(22278353)is greatly appreciated。
文摘Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability.
基金supported by the National Key Research and Development Project (No.2020YFA0907400)Strategic Priority Research Program of the Chinese Academy of Sciences (No.XDPB2005)+2 种基金National Natural Science Foundation of China(No.21777178)the National Young Top-Notch Talents (No.W03070030)Youth Innovation Promotion Association of the Chinese Academy of Sciences (No.Y202011)。
文摘Single particle-inductively coupled plasma mass spectrometry (SP-ICP-MS) is a powerful tool for size-characterization of metal-containing nanoparticles (MCNs) at environmentally relevant concentrations,however,coexisting dissolved metal ions greatly interfere with the accuracy of particle size analysis.The purpose of this study is to develop an online technique that couples hollow fiber ultrafiltration (HFUF) with SP-ICP-MS to improve the accuracy and size detection limit of MCNs by removing metal ions from suspensions of MCNs.Through systematic optimization of conditions including the type and concentration of surfactant and complexing agent,carrier pH,and ion cleaning time,HFUF completely removes metal ions but retains the MCNs in suspension.The optimal conditions include using a mixture of 0.05 vol.%FL-70 and 0.5 mmol/L Na2S2O_(3)(pH=8.0) as the carrier and 4 min as the ion cleaning time.At these conditions,HFUF-SP-ICP-MS accurately determines the sizes of MCNs,and the results agree with the size distribution determined by transmission electron microscopy,even when metal ions also are present in the sample.In addition,reducing the ionic background through HFUF also lowers the particle size detection limit with SP-ICP-MS (e.g.,from 28.3 to 14.2 nm for gold nanoparticles).This size-based ion-removal principle provided by HFUF is suitable for both cations (e.g.,Ag+) and anions (e.g.,AuCl_(4)^(-)) and thus has good versatility compared to ion exchange purification and promising prospects for the removal of salts and macromolecules before single particle analysis.
基金financially supported by the Key University Science Research Project of Jiangsu Province(No.17KJA130002)the Natural Science Foundation of Jiangsu Province(No.BK20201031)+1 种基金the National Key R&D Program of China(Grant No.2021YFA1200203)the National Natural Science Foundation of China(Grant Nos.51971112 and 52071181).
文摘The excellent dislocation storage ability of bulk multi-principal element alloys(MPEAs)has been widely reported.To date,however,the underlying mechanisms of dislocation escape behavior in small-size facecentered cubic(FCC)MPEAs have rarely been studied.Here,we quantitatively control the initial dislocation densities(-10^(15) m^(-2) and -10^(16) m^(-2))by large-scale molecular dynamics(MD)simulations and perform uniaxial compression simulations to compare the dislocation starvation behavior of CrCoNi with pure Cu single crystal pillars(SCPs).The analysis reveals that the CrCoNi SCPs with low initial dislocation density(-10^(15) m^(-2))can continuously accommodate mobile dislocations,and the critical dimension for dislocation starvation is about 30 nm.In particular,the CrCoNi SCPs with chemical short-range ordering(SRO)exhibit better dislocation storage and multiplication abilities than the random solid solution(RSS)samples even when the initial dislocation density is low.However,the presence of a large number of pre-existing dislocation locks governs the strong dislocation multiplication ability of the small-size RSS CrCoNi SCPs,in obvious contrast to the deformation of all pure Cu SCPs which is completely dominated by intermittent mobile dislocation starvation.Most importantly,we reveal the fundamental physics for the good dislocation storage of CrCoNi SCPs at small sizes from the perspective of chemical heterogeneity.The new phenomena reported in this work provide a unique atomic-scale perspective for understanding the microscopic physical origin of the mechanical behavior of MPEAs and the discovery of extremely slow dislocation escape behavior in small-scaled pillars,providing a reliable basis for the development of the dislocation starvation model.
基金supported by the National Natural Science Foundation of China (Nos10425210 and 10832002)the National Basic Research Program of China (No2006CB601202)the National High Technology Research and Development Program of China (No2006AA03Z519)
文摘The stress-strain behavior and copper are studied by the molecular dynamics incipient yield surface of nanoporous single crystal （MD） method. The problem is modeled by a periodic unit cell subject to multi-axial loading. The loading induced defect evolution is explored. The incipient yield surfaces are found to be tension-compression asymmetric. For a given void volume fraction, apparent size effects in the yield surface are predicted： the smaller behaves stronger. The evolution pattern of defects （i.e., dislocation and stacking faults） is insensitive to the model size and void volume fraction. However, it is loading path dependent. Squared prismatic dislocation loops dominate the incipient yielding under hydrostatic tension while stacking-faults are the primary defects for hydrostatic compression and uniaxial tension/compression.
基金Supported by the National Natural Science Foundation of China (Grant No. 20775042)the National Basic Research Program of China (Grant No. 2007CB714507)
文摘A microfluidic device to control single crystallization on the micron scale has been developed. The salt solution was stored in the nano-volume gaps between the arrays of protrudent circular plots in the microchip. The mixed organic solvent was injected into the chip as the counter diffusion phase for crystallization forming. This device provides a liquid-liquid interface through which only one phase flows while the other stays at the fixed plot. Therefore, it is possible to control the position of crystallization on the fixed plot. We can control the size and the uniformity of single crystals from 5 to 50 μm in length by adjusting the relative factors, such as interface lifetime, breeds of the mix-organic solvents and injecting velocities. The longer interface lifetime and lower organic solvent injecting velocities can bring up larger and more asymmetric crystals, which nearly shows the same trend compared with the macroscopic crystallization. Finally, the effect of the surfactant on the crystallization in the microdevice was studied. By adding the surfactant into the liquid-liquid interface, smaller sizes of crystals can be obtained without changing the crystal configuration.
基金supported by grants from the National High Technology R&D Program of China (200810Z133)the National Key Technology R&D Program of China (2006BAD01A08)the Fundamental Research of Chinese Academy of Agricultural Sciences (2009qn-5)
文摘The erythropoietin receptor （EPOR） has shown to play an important role in fetal survival by promoting the maturation of red blood cells in many studies of uterine capacity and litter size in swine. In this study, we screened the porcine EPOR gene for mutations and identified five single nucleotide polymorphisms （SNPs）： g.705G〉T in intron 1, g.2 373C〉T in intron 4, and g.2 882C〉T, g.3 035A〉G, and g.3 132A〉T in intron 6. We then genotyped 247 Beijing Black （BB） sows and compared the polymorphism data with the litter sizes of 1 375 parities among the sows. At first parity, there was no association of g.2 882C〉T and g.3 132A〉T with litter sizes. However, the CT sows in g.2 882C〉T had 2.13 higher total number born （TNB） （P〈0.01） and 1.81 higher number born alive （NBA） （P〈0.01） than the CC sows and the heterozygous sows in g.3 132A〉T had the highest litter size when compared to the two homozygotes for the later parities （P〈0.05）. In the g.3 035A〉G SNP, for the later parities, the TNB of the sows with the GG genotype was 3.81 higher （P〈0.01） and the NBA was 2.75 higher （P〈0.01） than that with the AA genotype but no difference at first parity. The G allele of the EPOR g.705G〉T SNP was associated with a greater litter size at both the first parity （P〈0.05） and later parities （P〈0.01）. Furthermore, we determined the allele frequencies for this SNP among five Chinese indigenous pig breeds （Erhualian, Laiwu Black, Meishan, Min, and Rongchang） and three western commercial pig breeds （Duroc, Landrace, and Large White）. The G allele of the EPOR g.705G〉T SNP was significantly more common in the more prolific Chinese breeds. These results indicated that the EPOR could be an important candidate gene for litter size and g.705G〉T can serve as a useful genetic marker for improving litter size in both first and later parities in swine.
