Semi-solid slurry of A356 alloy was prepared by low superheat pouring and slightly electromagnetic stirring, and the fractal characteristics of morphology in semi-solid primary phase was researched. The fractal dimens...Semi-solid slurry of A356 alloy was prepared by low superheat pouring and slightly electromagnetic stirring, and the fractal characteristics of morphology in semi-solid primary phase was researched. The fractal dimensions of primary phase morphology in the semi-solid A356 alloy were calculated by the program written to calculate the fractal dimensions of box-counting in the image of solid phase morphology in semi-solid metal slurry. The results indicated that the morphology of primary phase in semi-solid A356 prepared by low superheat pouring and slightly electromagnetic stirring is characterized by fractal dimension, and the primary phase morphology obtained by the different processing parameters has different fractal dimensions. The morphology of primary phase at the different position of ingot has different fractal dimensions, which reflected the effect of solidified conditions at different positions in the same ingot on the morphology of semi-solid primary phase. Solidification of semi-solid alloy is a course of change in fractal dimension.展开更多
The yellow-colored line of pearl oyster Pinctada fucata martensii displays a yellow prismatic layer and a white nacreous layer that can be used as an ideal model for research on shell color formation.Micro-Raman spect...The yellow-colored line of pearl oyster Pinctada fucata martensii displays a yellow prismatic layer and a white nacreous layer that can be used as an ideal model for research on shell color formation.Micro-Raman spectroscopy and transcriptome analyses were performed to explore the potential molecular mechanism underlying the phenotype differentiation.The micro-Raman spectroscopy results indicate that the prismatic layer exhibits distinct characteristic peaks of carotenoids,while these peaks are not prominent in the nacreous layer.In the transcriptome comparison of the central zone of mantle and mantle edge tissue,which function in nacreous and prismatic layer formation,respectively,935 significantly differentially expressed genes(DEGs)were identified,with 385 genes upregulated and 227 genes downregulated(|log_(2)(Fold change)|>1 and false discovery rate<0.05)in the mantle edge tissue.Among these genes,some were associated with melanoma/melanogenesis,such as tyrosinase,zinc metalloprotease,glutathione S-transferase,and ATP-binding cassette sub-family;some were associated with the carotenoid-related pathway,including scavenger receptors,cytochrome P450 and lipoprotein receptor.Genes associated with porphyrin metabolism,including porphobilinogen deaminase,and copper/zinc superoxide dismutase,and genes associated with shell matrix protein,including amorphous calcium carbonate binding protein,shematrin,PIF,and collagen,also exhibited significantly different expressions.It is speculated that the different colours between prismatic layer and nacreous layer in the yellow-colored line of P.f.martensii might be resulted from melanin,carotenoids and porphyrin metabolism,while genes related to shell structure and biomineralization might also affect coloration.Our results provide new insights to understand the mechanism of shell color formation in mollusca.展开更多
The fractal dimensions of primary phase morphology in semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring were calculated,and the effect of pouring temperature on fractal dime...The fractal dimensions of primary phase morphology in semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring were calculated,and the effect of pouring temperature on fractal dimension of primary phase morphology in semi-solid A356 alloy was researched.The results indicate that it is feasible to prepare semisolid A356 alloy slurry by low superheat pouring and slightly electromagnetic stirring,and there is an important effect of pouring temperature on the morphology and the grain size of the primary phase in semi-solid A356 alloy,in which the reduction of pouring temperature can obviously improve grain size and shape factor of primary phase in semi-solid A356 alloy under the condition of a certain stirring power.The primary phase morphology of semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring can be characterized by fractal dimension,and the primary phase morphology obtained by the different processing parameters has the different fractal dimensions.Solidification of semi-solid alloy is a course of change in fractal dimension.展开更多
Electromagnetic waves generated by electronic equipment are widely present in all living and working spaces because of the rapid development of electronic products and frequent use of digital systems.Electromagnetic s...Electromagnetic waves generated by electronic equipment are widely present in all living and working spaces because of the rapid development of electronic products and frequent use of digital systems.Electromagnetic shielding is an effective method of protection against these waves.Therefore,the demand for materials with high electromagnetic shielding properties has remarkably increased.Magnesium(Mg)alloys,as potential electromagnetic shielding materials,have sparked great interest worldwide.This review highlights the effects of grain size,texture,alloying elements and second phase on the shielding properties of Mg alloys.Recent progress on the shielding properties of Mg–Zn,Mg–Al,Mg–RE and other new shielding Mg alloys is then summarised,and the successful design of Mg alloys with superior electromagnetic shielding properties,such as Mg–Zn–Y–Ce–Zr,Mg–Sn–Zn–Ca–Ce,Mg–Gd–Y–Zn–Zr and Mg-based composite materials,is described.Finally,this review provides insights into the future development and applications of Mg alloys with superior shielding properties.展开更多
Semi-solid Al7Si0.3Mg alloy slurry, which is grain-refined by yttrium, is manufactured by low temperature pouring. The effects of grain-refined by yttrium on the morphology and the grain size of the primary α-Al in s...Semi-solid Al7Si0.3Mg alloy slurry, which is grain-refined by yttrium, is manufactured by low temperature pouring. The effects of grain-refined by yttrium on the morphology and the grain size of the primary α-Al in semi-solid Al7Si0.3Mg alloy are researched. The results indicate that semi-solid Al7Si0.3Mg alloy with particle-like and rosette-like primary α-Al can be prepared by low temperature pouring from liquid Al7Si0.3Mg alloy grain-refined by yttrium. The grain size and particle morphology of primary α-Al in Al7Si0.3Mg alloy are markedly improved by 0.5 wt pet Y. The refining mechanism of Y on the morphology and the grain size of the primary α-Al in semi-solid Al7Si0.3Mg alloy are delved.展开更多
The effects of slight electromagnetic stirring on morphology of primary phase in semisolid A356 prepared by low superheat pouring and slight electromagnetic stirring were researched,and some characteristic parameters ...The effects of slight electromagnetic stirring on morphology of primary phase in semisolid A356 prepared by low superheat pouring and slight electromagnetic stirring were researched,and some characteristic parameters characterized the morphology and grain size of the primary phase were calculated.The results indicate that the stirring power has an important effect on the morphology and the grain size.The characteristics of the morphology could be characterized by the fractal dimensions and the shape factors.The fractal dimension and the shape factor change when the morphology changes with processing conditions.Both increase with the increase of the stirring power,but the fractal dimension is still affected by the grain size.The increase of stirring power could obviously improve the grain size,fractal dimension and shape factor of the primary phase.展开更多
Inefficient charge separation and limited light absorption are two critical issues associated with high‐efficiency photocatalytic H2production using TiO2.Surface defects within a certain concentration range in photoc...Inefficient charge separation and limited light absorption are two critical issues associated with high‐efficiency photocatalytic H2production using TiO2.Surface defects within a certain concentration range in photocatalyst materials are beneficial for photocatalytic activity.In this study,surface defects(oxygen vacancies and metal cation replacement defects)were induced with a facile and effective approach by surface doping with low‐cost transition metals(Co,Ni,Cu,and Mn)on ultrafine TiO2.The obtained surface‐defective TiO2exhibited a3–4‐fold improved activity compared to that of the original ultrafine TiO2.In addition,a H2production rate of3.4μmol/h was obtained using visible light(λ>420nm)irradiation.The apparent quantum yield(AQY)at365nm reached36.9%over TiO2‐Cu,significantly more than the commercial P25TiO2.The enhancement of photocatalytic H2production activity can be attributed to improved rapid charge separation efficiency andexpanded light absorption window.This hydrothermal treatment with transition metal was proven to be a very facile and effective method for obtaining surface defects.展开更多
The unripe palmleaf raspberry,namely Fupenzi(FPZ),is an important medicinal and edible food.This study aims to evaluate the potential of FPZ extracts prepared with different approaches in attenuating hyperglycemia,gou...The unripe palmleaf raspberry,namely Fupenzi(FPZ),is an important medicinal and edible food.This study aims to evaluate the potential of FPZ extracts prepared with different approaches in attenuating hyperglycemia,gout,Alzheimer’s disease,and pigmentation,to obtain the enriching fraction and to identify the major active compounds.Results indicated that FPZ extracts showed weak activity against acetylcholinesterase,considerable ability against tyrosinase and xanthine oxidase,but excellent inhibition onα-glucosidase.Ultrasound-assisted 40%ethanol extract(40EUS)gave the highest phenolics content,and the bestα-glucosidase inhibition(IC_(50)=0.08μg/mL),which is 877-fold higher than that of positive control acarbose.The 40%ethanol eluting fraction of 40EUS showed the strongestα-glucosidase inhibition with the IC_(50) value of 37.79 ng/mL,it could also effectively attenuate the fasting blood glucose level and oral glucose tolerance of C57BL/6 mice.Twenty-six compounds were identified from 40%ethanol fraction by using HPLC-QTOF-MS/MS,hydrolysable tannins(including 11 ellagitannins and 4 gallotannins)were the major compounds,phenolic acids came to the second.Above results could provide important technical supporting for the further application and research of FPZ in health foods and drugs against diabetes.展开更多
In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550？欲espectively,using Gleeble-1500D system.And t...In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550？欲espectively,using Gleeble-1500D system.And the associated microstructural transformations and instability phenomena were studied by observations of the optical and transmission electron microscope.The power dissipation efficiency and instability parameter were calculated following the dynamic material model and plotted with the temperature and logarithm of strain rate to obtain processing maps for strains of 0.2,0.4,and 0.6.The processing maps present the instability zones at higher strain rates.The result shows that with increasing strain,the instability zones enlarge.The microstructural examination shows that the interface separates even the particle cracks or aligns along the shear direction of the adiabatic shear band in the instability zones.Two domains of higher efficiencies correspond to dynamic recovery and dynamic recrystallization during the hot deformation.Using the processing maps,the optimum processing parameters of stain rates and temperatures can be chosen for effective hot deformation of TiB2/6351 composites.展开更多
Due to the layer-by-layer manufacturing characteristics,metallurgical process of selective laser melting(SLM)is inherently dif-ferent in the building direction because of varying conditions,thereby resulting inter-lay...Due to the layer-by-layer manufacturing characteristics,metallurgical process of selective laser melting(SLM)is inherently dif-ferent in the building direction because of varying conditions,thereby resulting inter-layer heterogeneity.To mitigate such anisotropy,it is of great significance to understand the effects of processing parameters on the property evolution and thus metallurgy of fabrication process.This research proposes one-factor-at-a-time experiment to investigate the influences of laser power and scanning speed on the surface qual-ity,microstructures and mechanical properties of selective laser melted Ti-6Al-4V parts.Surface quality is assessed by roughness around the printings while mechanical properties are evaluated through microhardness and tensile strengths.Phases in microstructure are quantified by XRD to correlate with mechanical properties.Fracture morphology is analyzed to understand the effect of defects and microstructure on mechanical performance.The optimized parameter corresponding to best surface quality and mechanical properties has been found respect-ively in laser power of 190 W and scanning speed of 800 mm/s.After optimization,surface roughness has decreased by 44.47%for upper surface.Yielding strength,tensile strength and elongation rate have improved by 13.17%,43.34%and 64.51%,respectively,with similar hardness and Young’s modulus.In addition,heterogeneity of mechanical properties has great improvement by a range of 31.63%-92.68%.展开更多
High-temperature compressive deformation behaviors of Mg–6Zn–1.5Y–0.5Ce–0.4Zr alloy were investigated at temperatures and strain rates ranging from 523 to 673 K and from 0.001 to 1 s~(-1),respectively.The studied ...High-temperature compressive deformation behaviors of Mg–6Zn–1.5Y–0.5Ce–0.4Zr alloy were investigated at temperatures and strain rates ranging from 523 to 673 K and from 0.001 to 1 s~(-1),respectively.The studied alloy was mainly composed ofα-Mg,Mg_(3)Zn_(6)Y(I phase),Mg–Zn–Ce and Mg_(3)Zn_(3)Y_(2)(W phase).The constitutive equation of Mg alloy was obtained,and the apparent activation energy(Q)was determined as 200.44 k J/mol,indicating that rare earth phase increases the difficulty of deformation.The work hardening involves three stages:(1)linear hardening stage;(2)strain hardening stage;and(3)softening and steady-state stage.During these three stages,the dislocation aggregation and tangling,dynamic recovery and recrystallization occur sequentially.To characterize the dynamic recrystallization(DRX)volume fraction,the DRX kinetics was investigated using the Avrami-type equation.The deformation mechanism of magnesium alloy under different Zener–Hollomon parameter(Z)value conditions was also studied.At high Z values and intermediate conditions,dislocations rapidly generate and pile up in the alloy.Recrystallization is hardly seen at this time.At low Z condition,the DRX occurs in the alloy.展开更多
Single-atom catalysts(SACs)have been a research hotspot due to their high catalytic activity,selectivity,and atomic utilization rates.However,the theoretical research of SACs is relatively fragmented,which restricts f...Single-atom catalysts(SACs)have been a research hotspot due to their high catalytic activity,selectivity,and atomic utilization rates.However,the theoretical research of SACs is relatively fragmented,which restricts further understanding of SAC stability and activity.To address this issue,we report our analysis of the geometric structures,electronic characteristics,stabilities,catalytic activities,and descriptors of 132 graphene-based singleatom catalysts(M/GS)obtained from density functional theory calculations.Based on the calculated formation and binding energies,a stability map of M/GS was established to guide catalyst synthesis.The effects of metal atoms and support on the charge of metal atoms are discussed.The catalytic activities of M/GS in both nitrogen and oxygen reduction reactions are predicted based on the calculated magnetic moment and the adsorption energy.Combined with the electronegativity and d-band center,a two-dimensional descriptor is proposed to predict the O adsorption energy on M/GS.More importantly,this theoretical study provides predictive guidance for the preparation and rational design of highly stable and active single-atom catalysts using nitrogen doping on graphene.展开更多
Fault detection and diagnosis are essential to the air conditioning system of the data center for elevating reliability and reducing energy consumption.This study proposed a convolutional neural network(CNN)based data...Fault detection and diagnosis are essential to the air conditioning system of the data center for elevating reliability and reducing energy consumption.This study proposed a convolutional neural network(CNN)based data-driven fault detection and diagnosis model considering temporal dependency for composite air conditioning system that is capable of cooling the high heat flux in data centers.The input of fault detection and diagnosis model was an unsteady dataset generated by the experimentally validated transient mathematical model.The dataset concerned three typical faults,including refrigerant leakage,evaporator fan breakdown,and condenser fouling.Then,the CNN model was trained to construct a map between the input and system operating conditions.Further,the performance of the CNN model was validated by comparing it with the support vector machine and the neural network.Finally,the score-weighted class mapping activation method was utilized to interpret model diagnosis mechanisms and to identify key input features in various operating modes.The results demonstrated in the pump-driven heat pipe mode,the accuracy of the CNN model was 99.14%,increasing by around 8.5%compared with the other two methods.In the vapor compression mode,the accuracy of the CNN model achieved 99.9%and declined the miss rate of refrigerant leakage by at least 61%comparatively.The score-weighted class mapping activation results indicated the ambient temperature and the actuator-related parameters,such as compressor frequency in vapor compression mode and condenser fan frequency in pump-driven heat pipe mode,were essential features in system fault detection and diagnosis.展开更多
With‘Kyoho’grapes as the experimental material,the effects of different concentrations of chlorine dioxide(5,10 and 15 mg/L)and ozone(30,60and 90 mg/m^(3))fumigation on the contents of total phenols,proanthocyanidin...With‘Kyoho’grapes as the experimental material,the effects of different concentrations of chlorine dioxide(5,10 and 15 mg/L)and ozone(30,60and 90 mg/m^(3))fumigation on the contents of total phenols,proanthocyanidins and malondialdehyde(MDA)and the activity of polyphenol oxidase(PPO),peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)in the grapes during low temperature storage were compared and analyzed,hoping to provide reference for the storage and preservation of‘Kyoho’grapes after harvest.The results showed that compared with the control,certain concentrations of fumigant preservatives inhibited the degradation of total phenols and proanthocyanidins in‘Kyoho’grapes to varying degrees,maintained better cell membrane integrity,and inhibited the increase of MDA content and PPO activity,and in the later stage,more stable POD and higher activity of CAT and SOD were maintained.Comprehensive analysis showed that among the six fumigation treatments,10 mg/L ClO_(2)and 60 mg/m^(3)O_(3)could delay the aging process of grapes and maintain better antioxidant capacity and storage quality.展开更多
Pearl oyster Pinctada maxima is mainly used to produce high-valued gold and silver colored nucleated pearls.We developed a line with golden nacre in the mantle edge by sampling breeders from the Sanya population of pe...Pearl oyster Pinctada maxima is mainly used to produce high-valued gold and silver colored nucleated pearls.We developed a line with golden nacre in the mantle edge by sampling breeders from the Sanya population of pearl oyster P.maxima.It is found that the total carotenoid content(TCC)in the mantle tissues of the strain group(SG)was significantly higher than that of the control group(CG).Differentially expressed genes between the strain and control group(a line with silver nacre in the mantle edge)were screened.A total of 28285 genes were annotated in the transcriptome.Totally,295 up-regulated genes and 254 down-regulated genes were annotated which the strain compared with the CG.Lipid-transport and metabolism genes,such as fatty acid-binding protein,cytochrome P4503A and ATP-binding cassette sub-family A were up-regulated in the line.The expression levels of candidate genes in the line were higher than those in the CG,which are basically consistent with the transcriptome results.These findings are helpful to understand carotenoid metabolism in golden colored nacre formation of pearl oyster P.maxima.展开更多
In the matrix factorization(MF)based collaborative filtering recommendation method,the most critical part is to deal with the interaction between the features of users and items.The mainstream approach is to use the i...In the matrix factorization(MF)based collaborative filtering recommendation method,the most critical part is to deal with the interaction between the features of users and items.The mainstream approach is to use the inner product for MF to describe the user-item relationship.However,as a shallow model,MF has its limitations in describing the relationship between data.In addition,when the size of the data is large,the performance of MF is often poor due to data sparsity and noise.This paper presents a model called PIDC,short for potential interaction data clustering based deep learning recommendation.First,it uses classifiers to filter and cluster recommended items to solve the problem of sparse training data.Second,it combines MF and multi-layer perceptron(MLP)to optimize the prediction effect,and the limitation of inner product on the model expression ability is eliminated.The proposed model PIDC is tested on two datasets.The experimental results show that compared with the existing benchmark algorithm,the model improved the recommendation effect.展开更多
Dielectric properties are validated to be correlated with the changes of food quality during 4℃ storage,thus it could be used as predictive indicators for the quality parameters of salmon(Salmo salar)during cold stor...Dielectric properties are validated to be correlated with the changes of food quality during 4℃ storage,thus it could be used as predictive indicators for the quality parameters of salmon(Salmo salar)during cold storage.An open-ended coaxial detection method was used to determine the dielectric properties(dielectric constantε'and dielectric lossε")of salmon at the frequency range of 20-2500 MHz,and to explore the relationship between dielectric properties and volatile base nitrogen(TVB-N),thiobarbituric acid reactants(TBARS),total viable counts(TVC),pH and K-value in salmon fillets during storage for 7 d.Results showed that the TVB-N,TBARS,TVC and K-value of salmon increased linearly with the increase of storage time,and the pH decreased firstly and increased subsequently.Also,the dielectric properties(ε'andε")decreased with the increase of frequency,and increased with the increase of storage time.During 7 d storage,ε"increased the most at the frequency of 27.12 and 40.68 MHz,while at the frequency of 915 MHz and 2450 MHz,the increase ofε"was smaller.Results analyzed by Pearson correlation analysis showed that significant correlation(p<0.01)was found betweenε"and TVB-N and TBARS at the frequency of 27.12,40.68,100.00,300 and 915 MHz.The results of the partial least square(PLS)model showed that all the determination coefficients(R2pred)were over 0.900.Especially for TBARS,the R2pred of PLS-ε'and PLS-ε"were 0.913 and 0.920,respectively,and the root mean square error of prediction(RMSEP)were 0.041 and 0.039,respectively.However,the highest R2pred for PLS-ε'and PLS-ε"both occurred in TVB-N.Also,the predicted values against measured values of TVB-N,TBARS and TVC of salmon presented a good linear relationship.The linear coefficient R2 of TVB-N,TBARS and TVC for PLS-ε'were 0.937,0.910 and 0.917 respectively,and 0.942,0.917 and 0.933 respectively for PLS-ε".The results demonstrated the dielectric properties combined with PLS analysis can be used as a rapid and non-destructive method to predict quality parameters of salmon during 4℃ storage and could be further applied to other aquatic products.展开更多
Objective: As a traditional medicinal plant listed in the Chinese Pharmacopeia, Physalis alkekengi L. var. franchetii(Mast.) Makino(PAF) has a long medicinal history and high economic value. PAF has immunomodulatory p...Objective: As a traditional medicinal plant listed in the Chinese Pharmacopeia, Physalis alkekengi L. var. franchetii(Mast.) Makino(PAF) has a long medicinal history and high economic value. PAF has immunomodulatory properties and can be used to treat acute lung injury and eczema.The aim of this study is to solve the problems of extraction and purification of active components from PAF. Materials and Methods: The solvent to be used for extraction and its concentration, the solid-to-liquid ratio, and extraction duration were investigated using a single-factor experiment.An orthogonal design(L_(9)[3^(4)]) was used to determine the optimum extraction conditions. After optimization, the sample’s concentrations and flow velocity, the eluents and their velocity, adsorption time, and the removed water volume were measured. The content of the five steroids in the sample was determined by high-performance liquid chromatography(HPLC). We also investigated the anti-inflammatory property of PAF calyxes before and after purification. Results: The optimum extraction and purification processes were determined by single-factor analysis.AB-8 was identified as the best macroporous adsorption resin for enrichment. After optimization, the average total steroid content was 71.83%,and the average recovery was 90% after purification. Among the five steroid components detected by HPLC, physalin F showed the highest content. Furthermore, the sample obtained after purification could significantly inhibit paw edema by egg whites induced. Conclusions: An environmentally-sustainable, efficient, and stable process was first optimized for enriching and purifying total steroids from PAF. The process has the potential for further development and utilization in the pharmaceutical industry.展开更多
With the substantial increase in image transmission,the demand for image security is increasing.Noise-like images can be obtained by conventional encryption schemes,and although the security of the images can be guara...With the substantial increase in image transmission,the demand for image security is increasing.Noise-like images can be obtained by conventional encryption schemes,and although the security of the images can be guaranteed,the noise-like images cannot be directly previewed and retrieved.Based on the rank-then-encipher method,some researchers have designed a three-pixel exact thumbnail preserving encryption(TPE2)scheme,which can be applied to balance the security and availability of images,but this scheme has low encryption efficiency.In this paper,we introduce an efficient exact thumbnail preserving encryption scheme.First,blocking and bit-plane decomposition operations are performed on the plaintext image.The zigzag scrambling model is used to change the bit positions in the lower four bit planes.Subsequently,an operation is devised to permute the higher four bit planes,which is an extended application of the hidden Markov model.Finally,according to the difference in bit weights in each bit plane,a bit-level weighted diffusion rule is established to generate an encrypted image and still maintain the same sum of pixels within the block.Simulation results show that the proposed scheme improves the encryption efficiency and can guarantee the availability of images while protecting their privacy.展开更多
基金supports of the National Natural Science Foundation of China (No.50374012)the Natural Science Foundation of Jiangxi Province(No.0650047)the Science and Technology Program of the Education Department of Jiangxi Province (No.GJJ09229)
文摘Semi-solid slurry of A356 alloy was prepared by low superheat pouring and slightly electromagnetic stirring, and the fractal characteristics of morphology in semi-solid primary phase was researched. The fractal dimensions of primary phase morphology in the semi-solid A356 alloy were calculated by the program written to calculate the fractal dimensions of box-counting in the image of solid phase morphology in semi-solid metal slurry. The results indicated that the morphology of primary phase in semi-solid A356 prepared by low superheat pouring and slightly electromagnetic stirring is characterized by fractal dimension, and the primary phase morphology obtained by the different processing parameters has different fractal dimensions. The morphology of primary phase at the different position of ingot has different fractal dimensions, which reflected the effect of solidified conditions at different positions in the same ingot on the morphology of semi-solid primary phase. Solidification of semi-solid alloy is a course of change in fractal dimension.
基金supported by the Science and Technology Program of Guangdong Province (No.2022A1515010030)the National Natural Science Foundation of China (No.32102817)+3 种基金the Program for Sientific Research Start-up Funds of Guangdong Ocean University (No.060302022304)the Department of Education of Guangdong Province (Nos.2020ZDZX1045 and 2021KCXTD026)the Earmarked Fund for CARS-49the Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (No.2023KJ146)。
文摘The yellow-colored line of pearl oyster Pinctada fucata martensii displays a yellow prismatic layer and a white nacreous layer that can be used as an ideal model for research on shell color formation.Micro-Raman spectroscopy and transcriptome analyses were performed to explore the potential molecular mechanism underlying the phenotype differentiation.The micro-Raman spectroscopy results indicate that the prismatic layer exhibits distinct characteristic peaks of carotenoids,while these peaks are not prominent in the nacreous layer.In the transcriptome comparison of the central zone of mantle and mantle edge tissue,which function in nacreous and prismatic layer formation,respectively,935 significantly differentially expressed genes(DEGs)were identified,with 385 genes upregulated and 227 genes downregulated(|log_(2)(Fold change)|>1 and false discovery rate<0.05)in the mantle edge tissue.Among these genes,some were associated with melanoma/melanogenesis,such as tyrosinase,zinc metalloprotease,glutathione S-transferase,and ATP-binding cassette sub-family;some were associated with the carotenoid-related pathway,including scavenger receptors,cytochrome P450 and lipoprotein receptor.Genes associated with porphyrin metabolism,including porphobilinogen deaminase,and copper/zinc superoxide dismutase,and genes associated with shell matrix protein,including amorphous calcium carbonate binding protein,shematrin,PIF,and collagen,also exhibited significantly different expressions.It is speculated that the different colours between prismatic layer and nacreous layer in the yellow-colored line of P.f.martensii might be resulted from melanin,carotenoids and porphyrin metabolism,while genes related to shell structure and biomineralization might also affect coloration.Our results provide new insights to understand the mechanism of shell color formation in mollusca.
基金Project(50374012)supported by the National Natural Science Foundation of ChinaProject(0650047)supported by the Natural Science Foundation of Jiangxi Province,China
文摘The fractal dimensions of primary phase morphology in semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring were calculated,and the effect of pouring temperature on fractal dimension of primary phase morphology in semi-solid A356 alloy was researched.The results indicate that it is feasible to prepare semisolid A356 alloy slurry by low superheat pouring and slightly electromagnetic stirring,and there is an important effect of pouring temperature on the morphology and the grain size of the primary phase in semi-solid A356 alloy,in which the reduction of pouring temperature can obviously improve grain size and shape factor of primary phase in semi-solid A356 alloy under the condition of a certain stirring power.The primary phase morphology of semi-solid A356 alloy prepared by low superheat pouring and slightly electromagnetic stirring can be characterized by fractal dimension,and the primary phase morphology obtained by the different processing parameters has the different fractal dimensions.Solidification of semi-solid alloy is a course of change in fractal dimension.
基金the financial supports from the National Natural Science Foundation of China(52171103)Fundamental Research Funds for the Central Universities(2020CDJDPT001 and cqu2018CDHB1A08)+3 种基金Guangdong Major Project of Basic and Applied Basic Research(2020B0301030006)Natural Science Foundation of Chongqing,China(cstc2019jcyj-msxm X0505)Science and Technology Research Program of Chongqing Municipal Education Commission(KJQN202101234)Opened-end Foundation of Chongqing Light Alloy Materials and Processing Engineering Technology Research Center(GCZX201902)
文摘Electromagnetic waves generated by electronic equipment are widely present in all living and working spaces because of the rapid development of electronic products and frequent use of digital systems.Electromagnetic shielding is an effective method of protection against these waves.Therefore,the demand for materials with high electromagnetic shielding properties has remarkably increased.Magnesium(Mg)alloys,as potential electromagnetic shielding materials,have sparked great interest worldwide.This review highlights the effects of grain size,texture,alloying elements and second phase on the shielding properties of Mg alloys.Recent progress on the shielding properties of Mg–Zn,Mg–Al,Mg–RE and other new shielding Mg alloys is then summarised,and the successful design of Mg alloys with superior electromagnetic shielding properties,such as Mg–Zn–Y–Ce–Zr,Mg–Sn–Zn–Ca–Ce,Mg–Gd–Y–Zn–Zr and Mg-based composite materials,is described.Finally,this review provides insights into the future development and applications of Mg alloys with superior shielding properties.
基金supported by the Natural Science Foundation of Jiangxi Province(No.0650047)the Science and Technology Program of the Education Departmentof Jiangxi Province (Nos.GJJ09229 and GJJ10470)
文摘Semi-solid Al7Si0.3Mg alloy slurry, which is grain-refined by yttrium, is manufactured by low temperature pouring. The effects of grain-refined by yttrium on the morphology and the grain size of the primary α-Al in semi-solid Al7Si0.3Mg alloy are researched. The results indicate that semi-solid Al7Si0.3Mg alloy with particle-like and rosette-like primary α-Al can be prepared by low temperature pouring from liquid Al7Si0.3Mg alloy grain-refined by yttrium. The grain size and particle morphology of primary α-Al in Al7Si0.3Mg alloy are markedly improved by 0.5 wt pet Y. The refining mechanism of Y on the morphology and the grain size of the primary α-Al in semi-solid Al7Si0.3Mg alloy are delved.
基金Project (50774007) supported by the National Natural Science Foundation of ChinaProject (0650047) supported by the National Natural Science Foundation of Jiangxi ProvinceProject(GJJ09229) supported by Science and Technology Program of the Education Department of Jiangxi Province
文摘The effects of slight electromagnetic stirring on morphology of primary phase in semisolid A356 prepared by low superheat pouring and slight electromagnetic stirring were researched,and some characteristic parameters characterized the morphology and grain size of the primary phase were calculated.The results indicate that the stirring power has an important effect on the morphology and the grain size.The characteristics of the morphology could be characterized by the fractal dimensions and the shape factors.The fractal dimension and the shape factor change when the morphology changes with processing conditions.Both increase with the increase of the stirring power,but the fractal dimension is still affected by the grain size.The increase of stirring power could obviously improve the grain size,fractal dimension and shape factor of the primary phase.
基金supported by the Double First‐rate Subject‐Food Science and Engineering Program of Hebei Province (2018SPGCA18)Young Tip‐top Talents Plan of Universities and Colleges in Hebei Province of China (BJ2017026)the Specific Foundation for Doctor in Hebei Agriculture University of China (ZD201709)~~
文摘Inefficient charge separation and limited light absorption are two critical issues associated with high‐efficiency photocatalytic H2production using TiO2.Surface defects within a certain concentration range in photocatalyst materials are beneficial for photocatalytic activity.In this study,surface defects(oxygen vacancies and metal cation replacement defects)were induced with a facile and effective approach by surface doping with low‐cost transition metals(Co,Ni,Cu,and Mn)on ultrafine TiO2.The obtained surface‐defective TiO2exhibited a3–4‐fold improved activity compared to that of the original ultrafine TiO2.In addition,a H2production rate of3.4μmol/h was obtained using visible light(λ>420nm)irradiation.The apparent quantum yield(AQY)at365nm reached36.9%over TiO2‐Cu,significantly more than the commercial P25TiO2.The enhancement of photocatalytic H2production activity can be attributed to improved rapid charge separation efficiency andexpanded light absorption window.This hydrothermal treatment with transition metal was proven to be a very facile and effective method for obtaining surface defects.
基金the financial support of National Natural Science Foundation of China(31860475)Key Youth Foundation of Jiangxi Province(20192ACB21011)Jiangxi“Shuangqian”Program(JXSQ2018101008).
文摘The unripe palmleaf raspberry,namely Fupenzi(FPZ),is an important medicinal and edible food.This study aims to evaluate the potential of FPZ extracts prepared with different approaches in attenuating hyperglycemia,gout,Alzheimer’s disease,and pigmentation,to obtain the enriching fraction and to identify the major active compounds.Results indicated that FPZ extracts showed weak activity against acetylcholinesterase,considerable ability against tyrosinase and xanthine oxidase,but excellent inhibition onα-glucosidase.Ultrasound-assisted 40%ethanol extract(40EUS)gave the highest phenolics content,and the bestα-glucosidase inhibition(IC_(50)=0.08μg/mL),which is 877-fold higher than that of positive control acarbose.The 40%ethanol eluting fraction of 40EUS showed the strongestα-glucosidase inhibition with the IC_(50) value of 37.79 ng/mL,it could also effectively attenuate the fasting blood glucose level and oral glucose tolerance of C57BL/6 mice.Twenty-six compounds were identified from 40%ethanol fraction by using HPLC-QTOF-MS/MS,hydrolysable tannins(including 11 ellagitannins and 4 gallotannins)were the major compounds,phenolic acids came to the second.Above results could provide important technical supporting for the further application and research of FPZ in health foods and drugs against diabetes.
文摘In situ TiB2 reinforced 6351 Al alloy composites were subjected to compression testing at strain rates and temperatures ranging from 0.001 to 10 s -1 and from 300 to 550？欲espectively,using Gleeble-1500D system.And the associated microstructural transformations and instability phenomena were studied by observations of the optical and transmission electron microscope.The power dissipation efficiency and instability parameter were calculated following the dynamic material model and plotted with the temperature and logarithm of strain rate to obtain processing maps for strains of 0.2,0.4,and 0.6.The processing maps present the instability zones at higher strain rates.The result shows that with increasing strain,the instability zones enlarge.The microstructural examination shows that the interface separates even the particle cracks or aligns along the shear direction of the adiabatic shear band in the instability zones.Two domains of higher efficiencies correspond to dynamic recovery and dynamic recrystallization during the hot deformation.Using the processing maps,the optimum processing parameters of stain rates and temperatures can be chosen for effective hot deformation of TiB2/6351 composites.
基金Project was supported by the Natural Science Foundation of Fujian Province(Grant No.2020J01873)Science and Technology Major Project of Fujian Province(Grant No.2020HZ03018)+1 种基金Fujian Provincial Foreign Cooperation Project of Science and Technology(Grant No.2020I1003)Fujian Provincial Special Project for Marine Economy Development(Grant No.2021-517).
文摘Due to the layer-by-layer manufacturing characteristics,metallurgical process of selective laser melting(SLM)is inherently dif-ferent in the building direction because of varying conditions,thereby resulting inter-layer heterogeneity.To mitigate such anisotropy,it is of great significance to understand the effects of processing parameters on the property evolution and thus metallurgy of fabrication process.This research proposes one-factor-at-a-time experiment to investigate the influences of laser power and scanning speed on the surface qual-ity,microstructures and mechanical properties of selective laser melted Ti-6Al-4V parts.Surface quality is assessed by roughness around the printings while mechanical properties are evaluated through microhardness and tensile strengths.Phases in microstructure are quantified by XRD to correlate with mechanical properties.Fracture morphology is analyzed to understand the effect of defects and microstructure on mechanical performance.The optimized parameter corresponding to best surface quality and mechanical properties has been found respect-ively in laser power of 190 W and scanning speed of 800 mm/s.After optimization,surface roughness has decreased by 44.47%for upper surface.Yielding strength,tensile strength and elongation rate have improved by 13.17%,43.34%and 64.51%,respectively,with similar hardness and Young’s modulus.In addition,heterogeneity of mechanical properties has great improvement by a range of 31.63%-92.68%.
基金financially supported by the National Key R&D Program of China(2016YFB0301100)the Natural Science Foundation of Chongqing,China(cstc2019jcyj-msxmX0505)the support of the“111 Project”(B16007)by the Ministry of Education and Fundamental Research Fund of Central Universities in China(Grant No.2018CDJDCL0019)。
文摘High-temperature compressive deformation behaviors of Mg–6Zn–1.5Y–0.5Ce–0.4Zr alloy were investigated at temperatures and strain rates ranging from 523 to 673 K and from 0.001 to 1 s~(-1),respectively.The studied alloy was mainly composed ofα-Mg,Mg_(3)Zn_(6)Y(I phase),Mg–Zn–Ce and Mg_(3)Zn_(3)Y_(2)(W phase).The constitutive equation of Mg alloy was obtained,and the apparent activation energy(Q)was determined as 200.44 k J/mol,indicating that rare earth phase increases the difficulty of deformation.The work hardening involves three stages:(1)linear hardening stage;(2)strain hardening stage;and(3)softening and steady-state stage.During these three stages,the dislocation aggregation and tangling,dynamic recovery and recrystallization occur sequentially.To characterize the dynamic recrystallization(DRX)volume fraction,the DRX kinetics was investigated using the Avrami-type equation.The deformation mechanism of magnesium alloy under different Zener–Hollomon parameter(Z)value conditions was also studied.At high Z values and intermediate conditions,dislocations rapidly generate and pile up in the alloy.Recrystallization is hardly seen at this time.At low Z condition,the DRX occurs in the alloy.
基金the National Natural Science Foundation of China(No.91545122)Beijing Natural Science Foundation(2182066)+1 种基金Natural Science Foundation of Hebei Province of China(B2018502067)the Fundamental Research Funds for the Central Universities(2017XS121).
文摘Single-atom catalysts(SACs)have been a research hotspot due to their high catalytic activity,selectivity,and atomic utilization rates.However,the theoretical research of SACs is relatively fragmented,which restricts further understanding of SAC stability and activity.To address this issue,we report our analysis of the geometric structures,electronic characteristics,stabilities,catalytic activities,and descriptors of 132 graphene-based singleatom catalysts(M/GS)obtained from density functional theory calculations.Based on the calculated formation and binding energies,a stability map of M/GS was established to guide catalyst synthesis.The effects of metal atoms and support on the charge of metal atoms are discussed.The catalytic activities of M/GS in both nitrogen and oxygen reduction reactions are predicted based on the calculated magnetic moment and the adsorption energy.Combined with the electronegativity and d-band center,a two-dimensional descriptor is proposed to predict the O adsorption energy on M/GS.More importantly,this theoretical study provides predictive guidance for the preparation and rational design of highly stable and active single-atom catalysts using nitrogen doping on graphene.
基金the support from the National Natural Science Foundation of China(Grant number 52176180)the support from“the open competition mechanism to select the best candidates”key technology project of Liaoning(Grant 2022JH1/10800008).
文摘Fault detection and diagnosis are essential to the air conditioning system of the data center for elevating reliability and reducing energy consumption.This study proposed a convolutional neural network(CNN)based data-driven fault detection and diagnosis model considering temporal dependency for composite air conditioning system that is capable of cooling the high heat flux in data centers.The input of fault detection and diagnosis model was an unsteady dataset generated by the experimentally validated transient mathematical model.The dataset concerned three typical faults,including refrigerant leakage,evaporator fan breakdown,and condenser fouling.Then,the CNN model was trained to construct a map between the input and system operating conditions.Further,the performance of the CNN model was validated by comparing it with the support vector machine and the neural network.Finally,the score-weighted class mapping activation method was utilized to interpret model diagnosis mechanisms and to identify key input features in various operating modes.The results demonstrated in the pump-driven heat pipe mode,the accuracy of the CNN model was 99.14%,increasing by around 8.5%compared with the other two methods.In the vapor compression mode,the accuracy of the CNN model achieved 99.9%and declined the miss rate of refrigerant leakage by at least 61%comparatively.The score-weighted class mapping activation results indicated the ambient temperature and the actuator-related parameters,such as compressor frequency in vapor compression mode and condenser fan frequency in pump-driven heat pipe mode,were essential features in system fault detection and diagnosis.
基金Supported by Fund of Shanghai Agricultural Products Preservation Processing Engineering Technology Research Center(19DZ2251600)Fund of Shanghai Agricultural Products Preservation and Processing Professional Technical Service Platform(18DZ2291300)。
文摘With‘Kyoho’grapes as the experimental material,the effects of different concentrations of chlorine dioxide(5,10 and 15 mg/L)and ozone(30,60and 90 mg/m^(3))fumigation on the contents of total phenols,proanthocyanidins and malondialdehyde(MDA)and the activity of polyphenol oxidase(PPO),peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)in the grapes during low temperature storage were compared and analyzed,hoping to provide reference for the storage and preservation of‘Kyoho’grapes after harvest.The results showed that compared with the control,certain concentrations of fumigant preservatives inhibited the degradation of total phenols and proanthocyanidins in‘Kyoho’grapes to varying degrees,maintained better cell membrane integrity,and inhibited the increase of MDA content and PPO activity,and in the later stage,more stable POD and higher activity of CAT and SOD were maintained.Comprehensive analysis showed that among the six fumigation treatments,10 mg/L ClO_(2)and 60 mg/m^(3)O_(3)could delay the aging process of grapes and maintain better antioxidant capacity and storage quality.
基金supported by Guangdong Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams,Department of Agriculture and Rural Affairs of Guangdong Province(Grant No.2020KJ146)Special promotion of fishery science and technology of Ocean and Fisheries Bureau of Guangdong Province(Grant No.Z2014011 and Z2015002)+1 种基金"Innovation Team Project"special funds(Grant No.2017KCXTD016)from the Department of Education of Guangdong ProvinceModern Agricultural Industrial System(Grant No.CARS-049).
文摘Pearl oyster Pinctada maxima is mainly used to produce high-valued gold and silver colored nucleated pearls.We developed a line with golden nacre in the mantle edge by sampling breeders from the Sanya population of pearl oyster P.maxima.It is found that the total carotenoid content(TCC)in the mantle tissues of the strain group(SG)was significantly higher than that of the control group(CG).Differentially expressed genes between the strain and control group(a line with silver nacre in the mantle edge)were screened.A total of 28285 genes were annotated in the transcriptome.Totally,295 up-regulated genes and 254 down-regulated genes were annotated which the strain compared with the CG.Lipid-transport and metabolism genes,such as fatty acid-binding protein,cytochrome P4503A and ATP-binding cassette sub-family A were up-regulated in the line.The expression levels of candidate genes in the line were higher than those in the CG,which are basically consistent with the transcriptome results.These findings are helpful to understand carotenoid metabolism in golden colored nacre formation of pearl oyster P.maxima.
基金the National Key Research and Development Program of China(2017YFB1401300,2017YFB1401301)the National Natural Science Foundation of China(61902194)+2 种基金the Outstanding Youth of Jiangsu Natural Science Foundation(BK20170100)the Key Research and Development Program of Jiangsu(BE2017166)the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJB520046)。
文摘In the matrix factorization(MF)based collaborative filtering recommendation method,the most critical part is to deal with the interaction between the features of users and items.The mainstream approach is to use the inner product for MF to describe the user-item relationship.However,as a shallow model,MF has its limitations in describing the relationship between data.In addition,when the size of the data is large,the performance of MF is often poor due to data sparsity and noise.This paper presents a model called PIDC,short for potential interaction data clustering based deep learning recommendation.First,it uses classifiers to filter and cluster recommended items to solve the problem of sparse training data.Second,it combines MF and multi-layer perceptron(MLP)to optimize the prediction effect,and the limitation of inner product on the model expression ability is eliminated.The proposed model PIDC is tested on two datasets.The experimental results show that compared with the existing benchmark algorithm,the model improved the recommendation effect.
基金The authors acknowledge the National Natural Science Foundation of China(Grant No.31801613)for financial support to this research,and Professor Peng Zhang from Xidian University for his assistance in the data processing.
文摘Dielectric properties are validated to be correlated with the changes of food quality during 4℃ storage,thus it could be used as predictive indicators for the quality parameters of salmon(Salmo salar)during cold storage.An open-ended coaxial detection method was used to determine the dielectric properties(dielectric constantε'and dielectric lossε")of salmon at the frequency range of 20-2500 MHz,and to explore the relationship between dielectric properties and volatile base nitrogen(TVB-N),thiobarbituric acid reactants(TBARS),total viable counts(TVC),pH and K-value in salmon fillets during storage for 7 d.Results showed that the TVB-N,TBARS,TVC and K-value of salmon increased linearly with the increase of storage time,and the pH decreased firstly and increased subsequently.Also,the dielectric properties(ε'andε")decreased with the increase of frequency,and increased with the increase of storage time.During 7 d storage,ε"increased the most at the frequency of 27.12 and 40.68 MHz,while at the frequency of 915 MHz and 2450 MHz,the increase ofε"was smaller.Results analyzed by Pearson correlation analysis showed that significant correlation(p<0.01)was found betweenε"and TVB-N and TBARS at the frequency of 27.12,40.68,100.00,300 and 915 MHz.The results of the partial least square(PLS)model showed that all the determination coefficients(R2pred)were over 0.900.Especially for TBARS,the R2pred of PLS-ε'and PLS-ε"were 0.913 and 0.920,respectively,and the root mean square error of prediction(RMSEP)were 0.041 and 0.039,respectively.However,the highest R2pred for PLS-ε'and PLS-ε"both occurred in TVB-N.Also,the predicted values against measured values of TVB-N,TBARS and TVC of salmon presented a good linear relationship.The linear coefficient R2 of TVB-N,TBARS and TVC for PLS-ε'were 0.937,0.910 and 0.917 respectively,and 0.942,0.917 and 0.933 respectively for PLS-ε".The results demonstrated the dielectric properties combined with PLS analysis can be used as a rapid and non-destructive method to predict quality parameters of salmon during 4℃ storage and could be further applied to other aquatic products.
基金supported by the Guangzhou Science and Technology Program in 2020-Basic and Applied Basic Research Project(Grant No.202002030226)the National Natural Science Foundation of China(Grant No.82174043)the Guangdong Basic and Applied Basic Research Foundation(Grant No.2021A1515011697).
文摘Objective: As a traditional medicinal plant listed in the Chinese Pharmacopeia, Physalis alkekengi L. var. franchetii(Mast.) Makino(PAF) has a long medicinal history and high economic value. PAF has immunomodulatory properties and can be used to treat acute lung injury and eczema.The aim of this study is to solve the problems of extraction and purification of active components from PAF. Materials and Methods: The solvent to be used for extraction and its concentration, the solid-to-liquid ratio, and extraction duration were investigated using a single-factor experiment.An orthogonal design(L_(9)[3^(4)]) was used to determine the optimum extraction conditions. After optimization, the sample’s concentrations and flow velocity, the eluents and their velocity, adsorption time, and the removed water volume were measured. The content of the five steroids in the sample was determined by high-performance liquid chromatography(HPLC). We also investigated the anti-inflammatory property of PAF calyxes before and after purification. Results: The optimum extraction and purification processes were determined by single-factor analysis.AB-8 was identified as the best macroporous adsorption resin for enrichment. After optimization, the average total steroid content was 71.83%,and the average recovery was 90% after purification. Among the five steroid components detected by HPLC, physalin F showed the highest content. Furthermore, the sample obtained after purification could significantly inhibit paw edema by egg whites induced. Conclusions: An environmentally-sustainable, efficient, and stable process was first optimized for enriching and purifying total steroids from PAF. The process has the potential for further development and utilization in the pharmaceutical industry.
基金supported by the Pre-research Project of Songshan Laboratory,China(No.YYJC012022011)the Postgraduate Education Reform and Quality Improvement Project of Henan Province,China(Nos.YJS2022JD26 and SYLAL2023020)+2 种基金the Postgraduate Education Innovation Training Base,China(No.SYLJD2022008)the Science and Technology Project of Henan Province,China(Nos.232102210109 and 232102210096)the Open Foundation of Henan Key Laboratory of Cyberspace Situation Awareness,China(No.HNTS2022019)。
文摘With the substantial increase in image transmission,the demand for image security is increasing.Noise-like images can be obtained by conventional encryption schemes,and although the security of the images can be guaranteed,the noise-like images cannot be directly previewed and retrieved.Based on the rank-then-encipher method,some researchers have designed a three-pixel exact thumbnail preserving encryption(TPE2)scheme,which can be applied to balance the security and availability of images,but this scheme has low encryption efficiency.In this paper,we introduce an efficient exact thumbnail preserving encryption scheme.First,blocking and bit-plane decomposition operations are performed on the plaintext image.The zigzag scrambling model is used to change the bit positions in the lower four bit planes.Subsequently,an operation is devised to permute the higher four bit planes,which is an extended application of the hidden Markov model.Finally,according to the difference in bit weights in each bit plane,a bit-level weighted diffusion rule is established to generate an encrypted image and still maintain the same sum of pixels within the block.Simulation results show that the proposed scheme improves the encryption efficiency and can guarantee the availability of images while protecting their privacy.
