Size distribution of glutenin macropolymer （GMP） particles significantly affects the quality of final products in wheat. Six wheat varieties in eastern China were used for investigating the GMP content, particle siz...Size distribution of glutenin macropolymer （GMP） particles significantly affects the quality of final products in wheat. Six wheat varieties in eastern China were used for investigating the GMP content, particle size distribution and their relation. The results showed that the particle diameter of GMP changed from 0.38 μm to 269 μm. A typical bimodal curve of volume distribution of particles with peak values ranged from 4.44 μm to 5.36 μm and from 45.76 μm to 116.30 μm, respectively. Number distribution of particles showed the typical population with peak values in the range of 0.57-1.00 p.m. Proportions of granules 〈12μm, 12-80 μm and 〉80 μm were in the range of 17.1%-47.8%, 32.1%-50.3% and 10.2%-38.1% of total volume, respectively. The content of GMP was negatively correlated with the volume of GMP particles 〈12μm, but positively correlated with the volume of particles 〉80μm. The results suggested that the greater percentage of larger GMP particles is, the more GMP content there is in wheat grain.展开更多
Background: Despite the evidence about the increasing prevalence of dyslipidemia among adult obese Cameroonians, little is known about the Low-Density Lipoprotein (LDL) particles which influence lipid metabolism and a...Background: Despite the evidence about the increasing prevalence of dyslipidemia among adult obese Cameroonians, little is known about the Low-Density Lipoprotein (LDL) particles which influence lipid metabolism and affect cardiovascular status. The present study aims to assess the relationship between adiposity, LDL particles size and cardiovascular risk (CVR) among adult obese Cameroonians. Methods: A cross-sectional study was conducted from September 2015 to March 2016 on apparently healthy adults (n = 1006), aged 20 - 70 years and living in the West and North-West regions of Cameroon. Anthropometric measurements, blood pressure (BP), fasting blood glucose (FBG) and lipid profile markers were analyzed and LDL particle phenotypes (LDL phenotype A;LDL phenotype I;LDL phenotype B) were characterized using small, dense LDL-cholesterol (sdLDL-c) levels. Abdominal fat accumulation (AFA) was defined as waist circumference (WC) ≥ 88 cm (men) and ≥90 cm (women) and the CVR was assessed using Framingham score method. Results: In the overall population, 36.6% were overweight, 33.1% were obese and 69.1% were overweight/obese with AFA. The prevalence of LDL phenotype B was 19.8%, 37.5% and 42.8% respectively in normal-weight, overweight and obese. Among the obese, sdLDL and triglycerides levels correlated significantly with WC (r = 0.768;p Conclusion: Among obese Cameroonians, anthropometric markers of adiposity (BMI and WC) were strongly correlated to LDL phenotype B which was associated with high CVR dependently of AFA. SdLDL particles could exacerbate the CVR in obese Cameroonians subjects.展开更多
Bacterial cells are widely accepted as nucleation sites for calcium carbonate precipitation in biomineralization based on the Microbially Induced Carbonate Precipitation(MICP)process.For MICP-based insitu biotreatment...Bacterial cells are widely accepted as nucleation sites for calcium carbonate precipitation in biomineralization based on the Microbially Induced Carbonate Precipitation(MICP)process.For MICP-based insitu biotreatment,the firstproblem to be solved is how to introduce and retain the bacterial cells in the soil,which involves the migration and retention of bacterial cells during the biogrouting process.Soil particle size,a key factor in determining pore throat size,can have a significanteffect on the migration and retention of bacterial cells in the soil and therefore on biomineralization.To investigate the effect of particle size on the migration and retention of bacterial cells in sand and its biomineralization,two sets of tests were carried out in this study,including percolation tests and sand column treatment tests.Soil urease activity(definedas urease activity per unit mass of soil)and calcium carbonate content of the biomineralized sand were measured to comprehensively assess the migration and retention of bacterial cells in the sand.The results indicate that sands with a particle size smaller than 0.25 mmwould inhibit the migration of bacteria in the sand,resulting in a nonuniform distribution of precipitated calcium carbonate and a low strength enhancement of biomineralization.On the other hand,sands with a particle size larger than 1.18 mm are unfavorable for retaining bacterial cells in the sand,resulting in low calcium conversion efficiency.Meanwhile,particle size would also affect the formation of effective calcium carbonate through interparticle contact number and interparticle pore size,and thus biomineralization.展开更多
Rock-ice avalanches in cold high-mountain regions pose severe hazards due to their high mobility,yet the quantitative controls of particle-size ratio and ice content remain insufficiently constrained.This study invest...Rock-ice avalanches in cold high-mountain regions pose severe hazards due to their high mobility,yet the quantitative controls of particle-size ratio and ice content remain insufficiently constrained.This study investigates their coupled effects using inclinedflume experiments and Discrete Element Method(DEM)simulations,covering three gravel sizes(2-5 mm,5-7 mm,7-10 mm)and four ice-content levels(0%,20%,40%,60%).Run-out distance,velocity,energy components,flow regime(Savage number),and segregation indexαwere quantified.Increasing ice content significantly enhances mobility,but with diminishing marginal effectiveness.From 0%to 40%ice content,run-out distance increases by 41%-86%,whereas the additional increase from 40%to 60%contributes only 12%-23%.Particle-size ratio strongly governs segregation intensity.Fine-gravel groups reach segregation indices ofα=0.92-0.98,indicating nearly complete upward migration of ice,whereas medium-gravel and coarse-gravel groups exhibit much weaker segregation,stabilizing atα=0.68-0.74 and 0.60-0.69.Savage number analyses reveal marked flow-regime transitions.At 0%ice content,Savage numbers reach 1.0-1.5,indicating a collisional regime.Increasing ice content suppresses collisionality,with Savage numbers decreasing to 0.03-0.07 at 60%ice content,consistent with dense-regime flow.DEM energy analyses confirm this regime shift:for finegravel mixtures,collision energy decreases by 14%,while sliding-friction energy increases by 33%as ice content increases from 0%to 60%,reflecting enhanced overburden effects imposed by upward-segregated ice layers.Medium and coarse mixtures exhibit weaker or opposite energy-shift patterns,demonstrating strong size dependence.Mechanistically,large particle-size contrasts promote strong segregation and form dense basal rock layers that increase basal friction and reduce mobility.When particle sizes are similar or ice content is high,segregation remains limited,allowing ice to mix into the basal layer,thereby reducing basal friction and enhancing mobility.This research quantitatively demonstrates how composition controls particle spatial distribution,flow regime,and energy dissipation,offering new mechanistic insights into the propagation and deposition behaviors of rock-ice avalanches and improving hazard assessment in vulnerable high-mountain regions.展开更多
Small angle x-ray scattering(SAXS)is an advanced technique for characterizing the particle size distribution(PSD)of nanoparticles.However,the ill-posed nature of inverse problems in SAXS data analysis often reduces th...Small angle x-ray scattering(SAXS)is an advanced technique for characterizing the particle size distribution(PSD)of nanoparticles.However,the ill-posed nature of inverse problems in SAXS data analysis often reduces the accuracy of conventional methods.This article proposes a user-friendly software for PSD analysis,GranuSAS,which employs an algorithm that integrates truncated singular value decomposition(TSVD)with the Chahine method.This approach employs TSVD for data preprocessing,generating a set of initial solutions with noise suppression.A high-quality initial solution is subsequently selected via the L-curve method.This selected candidate solution is then iteratively refined by the Chahine algorithm,enforcing constraints such as non-negativity and improving physical interpretability.Most importantly,GranuSAS employs a parallel architecture that simultaneously yields inversion results from multiple shape models and,by evaluating the accuracy of each model's reconstructed scattering curve,offers a suggestion for model selection in material systems.To systematically validate the accuracy and efficiency of the software,verification was performed using both simulated and experimental datasets.The results demonstrate that the proposed software delivers both satisfactory accuracy and reliable computational efficiency.It provides an easy-to-use and reliable tool for researchers in materials science,helping them fully exploit the potential of SAXS in nanoparticle characterization.展开更多
More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation beha...More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130–480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and p H all affected fast aggregation rate coefficients of 130 nm nanoparticles. Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.展开更多
Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the s...Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the samples were characterized by X-ray diffraction （XRD）, BET equation, transmission electron microscopy （TEM）, and the corresponding selected area electron diffraction （SAED）. The experimental results indicate that the crystal structure of the samples is fcc structure the same as that of the bulk materials. The specific surface area is 11 m^2/g, the particle size distribution is 30 to 90 nm, and the average particle size is about 67 nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles with uniform size, high purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.展开更多
The objective of this study was to establish the dielectric properties of CoFe2O4 nanoparticles with particle sizes that varied from 28.6 to 5.8 nm. CoFe2O4 nanoparticles were synthesized using a chemical coprecipitat...The objective of this study was to establish the dielectric properties of CoFe2O4 nanoparticles with particle sizes that varied from 28.6 to 5.8 nm. CoFe2O4 nanoparticles were synthesized using a chemical coprecipitation method. The particle sizes were calculated accord-ing to the Scherrer formula using X-ray diffraction （XRD） peaks, and the particle size distribution curves were constructed by using field-emission scanning electron microscopy （FESEM） images. The dielectric permittivity and loss tangents of the samples were determined in the frequency range of 1 kHz to 1 MHz and in the temperature range of 300 to 10 K. Both the dielectric permittivity and the loss tangent were found to decrease with increasing frequency and decreasing temperature. For the smallest CoFe2O4 nanoparticle size, the dielectric per-mittivity and loss tangent exhibited their highest and lowest values, respectively. This behavior is very useful for materials used in devices that operate in the microwave or radio frequency ranges.展开更多
Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle ma...Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities. Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of BC concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.展开更多
The Dividing Distribution Function (DDF) method is one of the methods by which the particle size distribution of ultrafine powder can be evaluated from its small angle X-ray scattering data. In this paper, the stabili...The Dividing Distribution Function (DDF) method is one of the methods by which the particle size distribution of ultrafine powder can be evaluated from its small angle X-ray scattering data. In this paper, the stability of the solution obtained from DDF method has been investigated through optimizing the coefficient matrix, introducing a damping factor and a least square treatment. All calculations were accomplished with a microcomputer. It was shown that the average deviations of the size distribution obtained are not larger than the assigned random errors to the scattering intensities as long as the corresponding requirements are satisfied.展开更多
Controlling the particle size of catalyst to understand the active sites is the key to design efficient electrocatalysts toward hydrogen electrode reactions including hydrogen oxidation and evolution(HOR/HER).Herein, ...Controlling the particle size of catalyst to understand the active sites is the key to design efficient electrocatalysts toward hydrogen electrode reactions including hydrogen oxidation and evolution(HOR/HER).Herein, the hydrogen and hydroxyl adsorption on Ru/C could be effectively tuned for HOR/HER by simple controlling the particle sizes. It is found that the metallic Ru(Ru0) is the active site for HOR/HER, while oxidized Ru(Rux+) will hinder the adsorption and desorption of hydrogen on the catalyst. For the HOR,catalyst with small particles is more efficient, due to it is a three-phase interface reaction of gas on the surface of the catalyst. For the HER, the metallic state of Ru is crucial. The deconvolution of hydrogen peaks indicates that the catalytic sites with low hydrogen binding energy(HBE) shoulder the majority of the HOR activity. CO stripping curve further demonstrates that the stronger hydroxyl species(OHad)affinity is beneficial to promote the HOR performance. The results indicate that the design of efficient HOR/HER catalyst should focus on the balance between particle size and metallic states.展开更多
Pt/Al2O3 catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method,and the sulfated counterparts were prepared by impregnation of sulfuric acid.The turnover frequency...Pt/Al2O3 catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method,and the sulfated counterparts were prepared by impregnation of sulfuric acid.The turnover frequency of platinum for soot oxidation under loose contact conditions in a feed flow containing NO and O2 are positively correlated with the size of platinum.The sulfated Pt/Al2O3 exhibits higher catalytic activity for soot oxidation in the presence of NO despite their reduced ability for NO2 production.Such a contradiction is more significant for those catalysts with smaller platinum particles.Herein,the catalysts were characterized by X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET),transmission electron microscopy(TEM),inductive coupled plasma(ICP)emission spectrometry,CO chemisorption,thermogravimetric analysis(TGA),NH3 temperature-programmed desorption(NH 3-TPD),NO temperature-programmed oxidation(TPO)and NO x temperatureprogrammed desorption(TPD).Possible effect of Pt particle size for the catalytic oxidation of soot in the presence of NO was presented based primarily on the promoted NO2 transfer efficiency onto the soot pushed by the acidic catalysts.展开更多
The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at g...The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at global and regional scales have been widely examined,little attention has been paid to the trends in type-dependent AODs related to aerosol particle properties.Here,using the aerosol optical component dataset from the Multi-angle Imaging SpectroRadiometer(MISR)instrument,we investigate decadal-scale trends in total aerosol loading as well as AODs for five aerosol components by particle size and morphology during 2003–2018 over land.Relationships between the total AOD(TAOD)trends and type-dependent AOD changes were examined,and the relative contribution of each type-dependent AOD to the overall TAOD trends was quantified.By dividing the TAOD values into four different aerosol pollution levels(APLs)with splits at 0.15,0.40,and 0.80,we further explored the relationships between TAOD changes and interannual variations in the frequency-of-occurrences(FoOs)of these APLs.Long-term trends in FoOs in the different APLs show that there was a significant improvement in air quality between 2003 and 2018 in most land areas,except South Asia,corresponding to a shift from lightly polluted to clean conditions.However,the effects of different APLs on TAOD changes are regionally dependent and their extent of correlation varied spatially.Moreover,we observed that the annual mean TAOD has decreased by 0.47%.a^(-1)over land since 2003(P<0.05).This significant reduction was mainly attributed to the continued reduction in small-sized(<0.7 mm diameter)AOD(SAOD)(-0.74%.a^(-1))and spherical AOD(SPAOD)(-0.46%.a^(-1)).Statistical analysis shows that SAOD and SPAOD respectively accounted for 57.5%and 89.6%of the TAOD,but contributed 82.6%and 90.4%of the trend in TAOD.Our study suggests that small-sized and spherical aerosols composed of sulfate,organic matter,and black carbon play a dominant role in determining interannual variability in land TAOD.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
In recent years,the Cloud Imaging Probe(CIP)and Precipitation Imaging Probe(PIP)produced by Droplet Measurement Technologies(DMT)have been introduced by a number of meteorological research and operation centers in Chi...In recent years,the Cloud Imaging Probe(CIP)and Precipitation Imaging Probe(PIP)produced by Droplet Measurement Technologies(DMT)have been introduced by a number of meteorological research and operation centers in China.The supporting software provided by DMT,i.e.,PADS(Particle Analysis and Display System),cannot output detailed information on each individual particle,which definitely limits the in-depth utilization of cloud and precipitation particle image data in China.In this paper,particle-by-particle information was extracted by decompressing the CIP and PIP original particle image data,based on which a new definition of the dimension for nonspherical particles is proposed by using the area of the convex hull enclosing a particle to obtain the equivalent diameter of a circle with equal area.Based on the data detected during one flight in Inner Mongolia,the particle size distribution obtained using the new particle size definition and that used by the other four existing definitions are compared.The results show that the particle number concentration calculated using different particle size definitions can vary by up to an order of magnitude.The result obtained based on the new particle size definition is closest to that calculated with the area-equivalent diameter definition.展开更多
Hausmannite Mn3O4 nanoparticles were successfully prepared via a facile one-step solvothermal route with Mn（CH3COO）2·4H2O as manganese source in the mixed solvent of acetone and water.Powder X-ray diffraction（...Hausmannite Mn3O4 nanoparticles were successfully prepared via a facile one-step solvothermal route with Mn（CH3COO）2·4H2O as manganese source in the mixed solvent of acetone and water.Powder X-ray diffraction（XRD）,Fourier transform infrared（FTIR） spectrometry and transmission electron microscopy（TEM） were used to characterize Mn3O4 nanoparticles.It was found that the particle size could be tailored by varying the synthesis temperature.On the whole,the particle size becomes larger with the rising of solvothermal reaction temperature.But there is no linear relation between them.According to the different temperatures（60―140 °C）,the average particle size is from about 9 nm to 15 nm.Magnetic properties of Mn3O4 samples prepared at 60,100 and 140 °C were studied via a superconducting quantum interference device（SQUID）,respectively.展开更多
The need to continuously separate multiple microparticles is required for the recent development of lab-on-chip technology. Dielectrophoresis（DEP）-based separation device is extensively used in kinds of microfluidic...The need to continuously separate multiple microparticles is required for the recent development of lab-on-chip technology. Dielectrophoresis（DEP）-based separation device is extensively used in kinds of microfluidic applications. However, such conventional DEP-based device is relatively complicated and difficult for fabrication. A concise microfluidic device is presented for effective continuous separation of multiple size particle mixtures. A pair of acupuncture needle electrodes are creatively employed and embedded in a PDMS（poly-dimethylsiloxane） hurdle for generating non-uniform electric field thereby achieving a continuous DEP separation. The separation mechanism is that the incoming particle samples with different sizes experience different negative DEP（n DEP） forces and then they can be transported into different downstream outlets. The DEP characterizations of particles are calculated, and their trajectories are numerically predicted by considering the combined action of the incoming laminar flow and the n DEP force field for guiding the separation experiments. The device performance is verified by successfully separating a three-sized particle mixture, including polystyrene microspheres with diameters of 3 μm, 10 μm and 25 μm. The separation purity is below 70% when the flow rate ratio is less than 3.5 or more than 5.1, while the separation purity can be up to more than 90% when the flow rate ratio is between 3.5 and 5.1 and meanwhile ensure the voltage output falls in between 120 V and 150 V. Such simple DEP-based separation device has extensive applications in future microfluidic systems.展开更多
Sea salt aerosols play a critical role in regulating the global climate through their interactions with solar radiation.The size distribution of these particles is crucial in determining their bulk optical properties....Sea salt aerosols play a critical role in regulating the global climate through their interactions with solar radiation.The size distribution of these particles is crucial in determining their bulk optical properties.In this study,we analyzed in situ measured size distributions of sea salt aerosols from four field campaigns and used multi-mode lognormal size distributions to fit the data.We employed super-spheroids and coated super-spheroids to account for the particles’non-sphericity,inhomogeneity,and hysteresis effect during the deliquescence and crystallization processes.To compute the singlescattering properties of sea salt aerosols,we used the state-of-the-art invariant imbedding T-matrix method,which allows us to obtain accurate optical properties for sea salt aerosols with a maximum volume-equivalent diameter of 12μm at a wavelength of 532 nm.Our results demonstrated that the particle models developed in this study were successful in replicating both the measured depolarization and lidar ratios at various relative humidity(RH)levels.Importantly,we observed that large-size particles with diameters larger than 4μm had a substantial impact on the optical properties of sea salt aerosols,which has not been accounted for in previous studies.Specifically,excluding particles with diameters larger than 4μm led to underestimating the scattering and backscattering coefficients by 27%−38%and 43%−60%,respectively,for the ACE-Asia field campaign.Additionally,the depolarization ratios were underestimated by 0.15 within the 50%−70%RH range.These findings emphasize the necessity of considering large particle sizes for optical modeling of sea salt aerosols.展开更多
A new method was developed for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). Scattering effect of nanoparticles was studied . This method for the determination...A new method was developed for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). Scattering effect of nanoparticles was studied . This method for the determination of size distribution was statistical.展开更多
The microporous nanocry'sta1line TiO2 electrode with large surface roughness factor hasbeen prepared on a conducting glass support. Modification of the TiO2 electrode by in situ preparingquantum sized RuS2 particl...The microporous nanocry'sta1line TiO2 electrode with large surface roughness factor hasbeen prepared on a conducting glass support. Modification of the TiO2 electrode by in situ preparingquantum sized RuS2 particles on the surface of TiO2 electrode extends the optical absorptionspectrum and photocurrent action specmim into visible region. In addition, compared with RuS2 bulknlaterials- a blue shifi in both absorption spectrum and photocurrent action speCtrum of RuS2rriO2elcctrode is obserived and explained in terms of quantum sized effect.展开更多
基金Supported by the National Key Research and Development Program of China(2016YFD0300408)the Anhui Provincial Natural Science Foundation(1408085MC48)
文摘Size distribution of glutenin macropolymer （GMP） particles significantly affects the quality of final products in wheat. Six wheat varieties in eastern China were used for investigating the GMP content, particle size distribution and their relation. The results showed that the particle diameter of GMP changed from 0.38 μm to 269 μm. A typical bimodal curve of volume distribution of particles with peak values ranged from 4.44 μm to 5.36 μm and from 45.76 μm to 116.30 μm, respectively. Number distribution of particles showed the typical population with peak values in the range of 0.57-1.00 p.m. Proportions of granules 〈12μm, 12-80 μm and 〉80 μm were in the range of 17.1%-47.8%, 32.1%-50.3% and 10.2%-38.1% of total volume, respectively. The content of GMP was negatively correlated with the volume of GMP particles 〈12μm, but positively correlated with the volume of particles 〉80μm. The results suggested that the greater percentage of larger GMP particles is, the more GMP content there is in wheat grain.
文摘Background: Despite the evidence about the increasing prevalence of dyslipidemia among adult obese Cameroonians, little is known about the Low-Density Lipoprotein (LDL) particles which influence lipid metabolism and affect cardiovascular status. The present study aims to assess the relationship between adiposity, LDL particles size and cardiovascular risk (CVR) among adult obese Cameroonians. Methods: A cross-sectional study was conducted from September 2015 to March 2016 on apparently healthy adults (n = 1006), aged 20 - 70 years and living in the West and North-West regions of Cameroon. Anthropometric measurements, blood pressure (BP), fasting blood glucose (FBG) and lipid profile markers were analyzed and LDL particle phenotypes (LDL phenotype A;LDL phenotype I;LDL phenotype B) were characterized using small, dense LDL-cholesterol (sdLDL-c) levels. Abdominal fat accumulation (AFA) was defined as waist circumference (WC) ≥ 88 cm (men) and ≥90 cm (women) and the CVR was assessed using Framingham score method. Results: In the overall population, 36.6% were overweight, 33.1% were obese and 69.1% were overweight/obese with AFA. The prevalence of LDL phenotype B was 19.8%, 37.5% and 42.8% respectively in normal-weight, overweight and obese. Among the obese, sdLDL and triglycerides levels correlated significantly with WC (r = 0.768;p Conclusion: Among obese Cameroonians, anthropometric markers of adiposity (BMI and WC) were strongly correlated to LDL phenotype B which was associated with high CVR dependently of AFA. SdLDL particles could exacerbate the CVR in obese Cameroonians subjects.
基金support by the National Natural Science Foundation of China(NSFC)(Grant Nos.52178319,42477160,52338007).
文摘Bacterial cells are widely accepted as nucleation sites for calcium carbonate precipitation in biomineralization based on the Microbially Induced Carbonate Precipitation(MICP)process.For MICP-based insitu biotreatment,the firstproblem to be solved is how to introduce and retain the bacterial cells in the soil,which involves the migration and retention of bacterial cells during the biogrouting process.Soil particle size,a key factor in determining pore throat size,can have a significanteffect on the migration and retention of bacterial cells in the soil and therefore on biomineralization.To investigate the effect of particle size on the migration and retention of bacterial cells in sand and its biomineralization,two sets of tests were carried out in this study,including percolation tests and sand column treatment tests.Soil urease activity(definedas urease activity per unit mass of soil)and calcium carbonate content of the biomineralized sand were measured to comprehensively assess the migration and retention of bacterial cells in the sand.The results indicate that sands with a particle size smaller than 0.25 mmwould inhibit the migration of bacteria in the sand,resulting in a nonuniform distribution of precipitated calcium carbonate and a low strength enhancement of biomineralization.On the other hand,sands with a particle size larger than 1.18 mm are unfavorable for retaining bacterial cells in the sand,resulting in low calcium conversion efficiency.Meanwhile,particle size would also affect the formation of effective calcium carbonate through interparticle contact number and interparticle pore size,and thus biomineralization.
基金funded by the Natural Science Foundation of China(Grants No 42277127)。
文摘Rock-ice avalanches in cold high-mountain regions pose severe hazards due to their high mobility,yet the quantitative controls of particle-size ratio and ice content remain insufficiently constrained.This study investigates their coupled effects using inclinedflume experiments and Discrete Element Method(DEM)simulations,covering three gravel sizes(2-5 mm,5-7 mm,7-10 mm)and four ice-content levels(0%,20%,40%,60%).Run-out distance,velocity,energy components,flow regime(Savage number),and segregation indexαwere quantified.Increasing ice content significantly enhances mobility,but with diminishing marginal effectiveness.From 0%to 40%ice content,run-out distance increases by 41%-86%,whereas the additional increase from 40%to 60%contributes only 12%-23%.Particle-size ratio strongly governs segregation intensity.Fine-gravel groups reach segregation indices ofα=0.92-0.98,indicating nearly complete upward migration of ice,whereas medium-gravel and coarse-gravel groups exhibit much weaker segregation,stabilizing atα=0.68-0.74 and 0.60-0.69.Savage number analyses reveal marked flow-regime transitions.At 0%ice content,Savage numbers reach 1.0-1.5,indicating a collisional regime.Increasing ice content suppresses collisionality,with Savage numbers decreasing to 0.03-0.07 at 60%ice content,consistent with dense-regime flow.DEM energy analyses confirm this regime shift:for finegravel mixtures,collision energy decreases by 14%,while sliding-friction energy increases by 33%as ice content increases from 0%to 60%,reflecting enhanced overburden effects imposed by upward-segregated ice layers.Medium and coarse mixtures exhibit weaker or opposite energy-shift patterns,demonstrating strong size dependence.Mechanistically,large particle-size contrasts promote strong segregation and form dense basal rock layers that increase basal friction and reduce mobility.When particle sizes are similar or ice content is high,segregation remains limited,allowing ice to mix into the basal layer,thereby reducing basal friction and enhancing mobility.This research quantitatively demonstrates how composition controls particle spatial distribution,flow regime,and energy dissipation,offering new mechanistic insights into the propagation and deposition behaviors of rock-ice avalanches and improving hazard assessment in vulnerable high-mountain regions.
基金Project supported by the Project of the Anhui Provincial Natural Science Foundation(Grant No.2308085MA19)Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA0410401)+2 种基金the National Natural Science Foundation of China(Grant No.52202120)the National Key Research and Development Program of China(Grant No.2023YFA1609800)USTC Research Funds of the Double First-Class Initiative(Grant No.YD2310002013)。
文摘Small angle x-ray scattering(SAXS)is an advanced technique for characterizing the particle size distribution(PSD)of nanoparticles.However,the ill-posed nature of inverse problems in SAXS data analysis often reduces the accuracy of conventional methods.This article proposes a user-friendly software for PSD analysis,GranuSAS,which employs an algorithm that integrates truncated singular value decomposition(TSVD)with the Chahine method.This approach employs TSVD for data preprocessing,generating a set of initial solutions with noise suppression.A high-quality initial solution is subsequently selected via the L-curve method.This selected candidate solution is then iteratively refined by the Chahine algorithm,enforcing constraints such as non-negativity and improving physical interpretability.Most importantly,GranuSAS employs a parallel architecture that simultaneously yields inversion results from multiple shape models and,by evaluating the accuracy of each model's reconstructed scattering curve,offers a suggestion for model selection in material systems.To systematically validate the accuracy and efficiency of the software,verification was performed using both simulated and experimental datasets.The results demonstrate that the proposed software delivers both satisfactory accuracy and reliable computational efficiency.It provides an easy-to-use and reliable tool for researchers in materials science,helping them fully exploit the potential of SAXS in nanoparticle characterization.
基金supported by the National Natural Science Foundation of China(Nos.51808530 and 51778604)。
文摘More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130–480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and p H all affected fast aggregation rate coefficients of 130 nm nanoparticles. Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.
基金This work was financially supported by the Natural Science Foundation of Gansu Province, China (No. 3ZS042-B25-017)
文摘Copper nanoparticles were successfully prepared in large scale by means of anodic arc discharging plasma method in inert atmosphere. The particle size, specific surface area, crystal structure, and morphology of the samples were characterized by X-ray diffraction （XRD）, BET equation, transmission electron microscopy （TEM）, and the corresponding selected area electron diffraction （SAED）. The experimental results indicate that the crystal structure of the samples is fcc structure the same as that of the bulk materials. The specific surface area is 11 m^2/g, the particle size distribution is 30 to 90 nm, and the average particle size is about 67 nm obtained from TEM and confirmed from XRD and BET results. The nanoparticles with uniform size, high purity, narrow size distribution and spherical shape can be prepared by this convenient and effective method.
文摘The objective of this study was to establish the dielectric properties of CoFe2O4 nanoparticles with particle sizes that varied from 28.6 to 5.8 nm. CoFe2O4 nanoparticles were synthesized using a chemical coprecipitation method. The particle sizes were calculated accord-ing to the Scherrer formula using X-ray diffraction （XRD） peaks, and the particle size distribution curves were constructed by using field-emission scanning electron microscopy （FESEM） images. The dielectric permittivity and loss tangents of the samples were determined in the frequency range of 1 kHz to 1 MHz and in the temperature range of 300 to 10 K. Both the dielectric permittivity and the loss tangent were found to decrease with increasing frequency and decreasing temperature. For the smallest CoFe2O4 nanoparticle size, the dielectric per-mittivity and loss tangent exhibited their highest and lowest values, respectively. This behavior is very useful for materials used in devices that operate in the microwave or radio frequency ranges.
文摘Particle number and mass concentrations were measured in Beijing during the winter and summer periods in 2003, together with some other parameters including black carbon (BC) and meteorological conditions. Particle mass concentrations exhibited low seasonality, and the ratio of PM2.5/PM10 in winter was higher than that in summer. Particle number size distribution (PSD) was characterized by four modes and exhibited low seasonality. BC was well correlated with the number and mass concentrations of accumulation and coarse particles, indicating these size particles are related to anthropogenic activities. Particle mass and number concentrations (except ultra-fine and nucleation particles) followed well the trends of BC concentration for the majority of the day, indicating that most particles were associated with primary emissions. The diurnal number distributions of accumulation and coarse mode particles were characterized by two peaks.
文摘The Dividing Distribution Function (DDF) method is one of the methods by which the particle size distribution of ultrafine powder can be evaluated from its small angle X-ray scattering data. In this paper, the stability of the solution obtained from DDF method has been investigated through optimizing the coefficient matrix, introducing a damping factor and a least square treatment. All calculations were accomplished with a microcomputer. It was shown that the average deviations of the size distribution obtained are not larger than the assigned random errors to the scattering intensities as long as the corresponding requirements are satisfied.
基金supported by the National Natural Science Foundation (No. 91963109)。
文摘Controlling the particle size of catalyst to understand the active sites is the key to design efficient electrocatalysts toward hydrogen electrode reactions including hydrogen oxidation and evolution(HOR/HER).Herein, the hydrogen and hydroxyl adsorption on Ru/C could be effectively tuned for HOR/HER by simple controlling the particle sizes. It is found that the metallic Ru(Ru0) is the active site for HOR/HER, while oxidized Ru(Rux+) will hinder the adsorption and desorption of hydrogen on the catalyst. For the HOR,catalyst with small particles is more efficient, due to it is a three-phase interface reaction of gas on the surface of the catalyst. For the HER, the metallic state of Ru is crucial. The deconvolution of hydrogen peaks indicates that the catalytic sites with low hydrogen binding energy(HBE) shoulder the majority of the HOR activity. CO stripping curve further demonstrates that the stronger hydroxyl species(OHad)affinity is beneficial to promote the HOR performance. The results indicate that the design of efficient HOR/HER catalyst should focus on the balance between particle size and metallic states.
基金This work was supported by projects of the National Key R&D Program of China(No.2017YFC0211102)the Key Laboratory of Advanced Materials of the Ministry of Education.
文摘Pt/Al2O3 catalysts with mean Pt particle size ranged from 2.7 to 7.1 nm were synthesized by chemical reduction method,and the sulfated counterparts were prepared by impregnation of sulfuric acid.The turnover frequency of platinum for soot oxidation under loose contact conditions in a feed flow containing NO and O2 are positively correlated with the size of platinum.The sulfated Pt/Al2O3 exhibits higher catalytic activity for soot oxidation in the presence of NO despite their reduced ability for NO2 production.Such a contradiction is more significant for those catalysts with smaller platinum particles.Herein,the catalysts were characterized by X-ray diffraction(XRD),Brunauer-Emmett-Teller(BET),transmission electron microscopy(TEM),inductive coupled plasma(ICP)emission spectrometry,CO chemisorption,thermogravimetric analysis(TGA),NH3 temperature-programmed desorption(NH 3-TPD),NO temperature-programmed oxidation(TPO)and NO x temperatureprogrammed desorption(TPD).Possible effect of Pt particle size for the catalytic oxidation of soot in the presence of NO was presented based primarily on the promoted NO2 transfer efficiency onto the soot pushed by the acidic catalysts.
基金supported by the National Key Research and Development Program Pilot Projects of China(2016YFA0601901)the National Science Fund for Distinguished Young Scholars(41825011)the National Natural Science Foundation of China(42030608,41590874,and 41941011)。
文摘The optical and microphysical properties of aerosols remain one of the greatest uncertainties associated with evaluating the climate forcing attributed to aerosols.Although the trends in aerosol optical depth(AOD)at global and regional scales have been widely examined,little attention has been paid to the trends in type-dependent AODs related to aerosol particle properties.Here,using the aerosol optical component dataset from the Multi-angle Imaging SpectroRadiometer(MISR)instrument,we investigate decadal-scale trends in total aerosol loading as well as AODs for five aerosol components by particle size and morphology during 2003–2018 over land.Relationships between the total AOD(TAOD)trends and type-dependent AOD changes were examined,and the relative contribution of each type-dependent AOD to the overall TAOD trends was quantified.By dividing the TAOD values into four different aerosol pollution levels(APLs)with splits at 0.15,0.40,and 0.80,we further explored the relationships between TAOD changes and interannual variations in the frequency-of-occurrences(FoOs)of these APLs.Long-term trends in FoOs in the different APLs show that there was a significant improvement in air quality between 2003 and 2018 in most land areas,except South Asia,corresponding to a shift from lightly polluted to clean conditions.However,the effects of different APLs on TAOD changes are regionally dependent and their extent of correlation varied spatially.Moreover,we observed that the annual mean TAOD has decreased by 0.47%.a^(-1)over land since 2003(P<0.05).This significant reduction was mainly attributed to the continued reduction in small-sized(<0.7 mm diameter)AOD(SAOD)(-0.74%.a^(-1))and spherical AOD(SPAOD)(-0.46%.a^(-1)).Statistical analysis shows that SAOD and SPAOD respectively accounted for 57.5%and 89.6%of the TAOD,but contributed 82.6%and 90.4%of the trend in TAOD.Our study suggests that small-sized and spherical aerosols composed of sulfate,organic matter,and black carbon play a dominant role in determining interannual variability in land TAOD.
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jointly funded by the National Key R&D Program of China[grant numbers 2019YFC1510301 and 2018YFC1505702]the Basic Research Fund of the Chinese Academy of Meteorological Sciences[grant number 2020Z008].
文摘In recent years,the Cloud Imaging Probe(CIP)and Precipitation Imaging Probe(PIP)produced by Droplet Measurement Technologies(DMT)have been introduced by a number of meteorological research and operation centers in China.The supporting software provided by DMT,i.e.,PADS(Particle Analysis and Display System),cannot output detailed information on each individual particle,which definitely limits the in-depth utilization of cloud and precipitation particle image data in China.In this paper,particle-by-particle information was extracted by decompressing the CIP and PIP original particle image data,based on which a new definition of the dimension for nonspherical particles is proposed by using the area of the convex hull enclosing a particle to obtain the equivalent diameter of a circle with equal area.Based on the data detected during one flight in Inner Mongolia,the particle size distribution obtained using the new particle size definition and that used by the other four existing definitions are compared.The results show that the particle number concentration calculated using different particle size definitions can vary by up to an order of magnitude.The result obtained based on the new particle size definition is closest to that calculated with the area-equivalent diameter definition.
基金Supported by the National Natural Science Foundation of China(Nos.20631010,90922034)
文摘Hausmannite Mn3O4 nanoparticles were successfully prepared via a facile one-step solvothermal route with Mn（CH3COO）2·4H2O as manganese source in the mixed solvent of acetone and water.Powder X-ray diffraction（XRD）,Fourier transform infrared（FTIR） spectrometry and transmission electron microscopy（TEM） were used to characterize Mn3O4 nanoparticles.It was found that the particle size could be tailored by varying the synthesis temperature.On the whole,the particle size becomes larger with the rising of solvothermal reaction temperature.But there is no linear relation between them.According to the different temperatures（60―140 °C）,the average particle size is from about 9 nm to 15 nm.Magnetic properties of Mn3O4 samples prepared at 60,100 and 140 °C were studied via a superconducting quantum interference device（SQUID）,respectively.
基金Supported by National Natural Science Foundation of China(Grant No.51305106)Fundamental Research Funds for the Central Universities,China(Grant Nos.HIT.NSRIF.2014058,HIT.IBRSEM.201319)Open Foundation of State Key Laboratory of Fluid Power Transmission and Control,China(GZKF-201402)
文摘The need to continuously separate multiple microparticles is required for the recent development of lab-on-chip technology. Dielectrophoresis（DEP）-based separation device is extensively used in kinds of microfluidic applications. However, such conventional DEP-based device is relatively complicated and difficult for fabrication. A concise microfluidic device is presented for effective continuous separation of multiple size particle mixtures. A pair of acupuncture needle electrodes are creatively employed and embedded in a PDMS（poly-dimethylsiloxane） hurdle for generating non-uniform electric field thereby achieving a continuous DEP separation. The separation mechanism is that the incoming particle samples with different sizes experience different negative DEP（n DEP） forces and then they can be transported into different downstream outlets. The DEP characterizations of particles are calculated, and their trajectories are numerically predicted by considering the combined action of the incoming laminar flow and the n DEP force field for guiding the separation experiments. The device performance is verified by successfully separating a three-sized particle mixture, including polystyrene microspheres with diameters of 3 μm, 10 μm and 25 μm. The separation purity is below 70% when the flow rate ratio is less than 3.5 or more than 5.1, while the separation purity can be up to more than 90% when the flow rate ratio is between 3.5 and 5.1 and meanwhile ensure the voltage output falls in between 120 V and 150 V. Such simple DEP-based separation device has extensive applications in future microfluidic systems.
基金supported by the National Natural Science Foundation of China(Grant Nos.42022038,and 42090030).
文摘Sea salt aerosols play a critical role in regulating the global climate through their interactions with solar radiation.The size distribution of these particles is crucial in determining their bulk optical properties.In this study,we analyzed in situ measured size distributions of sea salt aerosols from four field campaigns and used multi-mode lognormal size distributions to fit the data.We employed super-spheroids and coated super-spheroids to account for the particles’non-sphericity,inhomogeneity,and hysteresis effect during the deliquescence and crystallization processes.To compute the singlescattering properties of sea salt aerosols,we used the state-of-the-art invariant imbedding T-matrix method,which allows us to obtain accurate optical properties for sea salt aerosols with a maximum volume-equivalent diameter of 12μm at a wavelength of 532 nm.Our results demonstrated that the particle models developed in this study were successful in replicating both the measured depolarization and lidar ratios at various relative humidity(RH)levels.Importantly,we observed that large-size particles with diameters larger than 4μm had a substantial impact on the optical properties of sea salt aerosols,which has not been accounted for in previous studies.Specifically,excluding particles with diameters larger than 4μm led to underestimating the scattering and backscattering coefficients by 27%−38%and 43%−60%,respectively,for the ACE-Asia field campaign.Additionally,the depolarization ratios were underestimated by 0.15 within the 50%−70%RH range.These findings emphasize the necessity of considering large particle sizes for optical modeling of sea salt aerosols.
文摘A new method was developed for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). Scattering effect of nanoparticles was studied . This method for the determination of size distribution was statistical.
文摘The microporous nanocry'sta1line TiO2 electrode with large surface roughness factor hasbeen prepared on a conducting glass support. Modification of the TiO2 electrode by in situ preparingquantum sized RuS2 particles on the surface of TiO2 electrode extends the optical absorptionspectrum and photocurrent action specmim into visible region. In addition, compared with RuS2 bulknlaterials- a blue shifi in both absorption spectrum and photocurrent action speCtrum of RuS2rriO2elcctrode is obserived and explained in terms of quantum sized effect.
