Flotation separation of calcite from fluorite is a challenge on low-grade fluorite flotation that limits the recovery and purity of fluorite concentrate.A new acid leaching–flotation process for fluorite is proposed ...Flotation separation of calcite from fluorite is a challenge on low-grade fluorite flotation that limits the recovery and purity of fluorite concentrate.A new acid leaching–flotation process for fluorite is proposed in this work.This innovative process raised the fluor-ite’s grade to 97.26wt%while producing nanoscale calcium carbonate from its leachate,which contained plenty of calcium ions.On the production of nanoscale calcium carbonate,the impacts of concentration,temperature,and titration rate were examined.By modifying the process conditions and utilizing crystal conditioning agents,calcite-type and amorphous calcium carbonates with corresponding particle sizes of 1.823 and 1.511μm were produced.The influence of the impurity ions Mn^(2+),Mg^(2+),and Fe^(3+)was demonstrated to reduce the particle size of nanoscale calcium carbonate and make crystal shape easier to manage in the fluorite leach solution system compared with the calcium chloride solution.The combination of the acid leaching–flotation process and the nanoscale calcium carbonate preparation method improved the grade of fluorite while recovering calcite resources,thus presenting a novel idea for the effective and clean usage of low-quality fluorite resources with embedded microfine particles.展开更多
This paper investigates rate adaptation schemes for decoding-and-forward (DF) relay system based on random projections codes (RPC). We consider a classic three node relay system model, where relay node performs on hal...This paper investigates rate adaptation schemes for decoding-and-forward (DF) relay system based on random projections codes (RPC). We consider a classic three node relay system model, where relay node performs on half-duplex mode. Then, we give out receiving diversity relay scheme and coding diversity relay scheme, and present their jointly decoding methods. Furthermore, we discuss the performance of the two schemes with different power allocation coefficients. Simulations show that our relay schemes can achieve different gain with the help of relay node. And, we should allocate power to source node to just guarantee relay node can decode successfully, and allocate remain power to relay node as far as possible. In this way, this DF relay system not only achieves diversity gain, but also achieves higher and smooth spectrum efficiency.展开更多
AIM:To explore a reasonable method of digestive tract reconstruction,namely,antrum-preserving double-tract reconstruction(ADTR),for patients with adenocarcinoma of the esophagogastric junction(AEG) and to assess its e...AIM:To explore a reasonable method of digestive tract reconstruction,namely,antrum-preserving double-tract reconstruction(ADTR),for patients with adenocarcinoma of the esophagogastric junction(AEG) and to assess its efficacy and safety in terms of longterm survival,complications,morbidity and mortality.METHODS:A total of 55 cases were retrospectively collected,including 18 cases undergoing ADTR and 37 cases of Roux-en-Y reconstruction(RY) for AEG(Siewert types Ⅱ and Ⅲ) at North Sichuan Medical College. The cases were divided into two groups. The clinicopathological characteristics,perioperative outcomes,postoperative complications,morbidity and overall survival(OS) were compared for the two different reconstruction methods.RESULTS:Basic characteristics including sex,age,body mass index(BMI),Siewert type,p T status,p N stage,and lymph node metastasis were similar in the two groups. No significant differences were found between the two groups in terms of perioperative outcomes(including the length of postoperative hospital stay,operating time,and intraoperative blood loss) and postoperative complications(consisting of anastomosis-related complications,wound infection,respiratory infection,pleural effusion,lymphorrhagia,and cholelithiasis). For the ADTR group,perioperativerecovery indexes such as time to first flatus(P = 0.002) and time to resuming a liquid diet(P = 0.001) were faster than those for the RY group. Moreover,the incidence of reflux esophagitis was significantly decreased compared with the RY group(P = 0.048). The postoperative morbidity and mortality rates for overall postoperative complications and the rates of tumor recurrence and metastasis were not significantly different between the two groups. Survival curves plotted using the Kaplan-Meier method and compared by log-rank test demonstrated similar outcomes for the ADTR and RY groups. Multivariate analysis of significantly different factors that presented as covariates on Cox regression analysis to assess the survival and recurrence among AEG patients showed that age,gender,BMI,pleural effusion,time to resuming a liquid diet,lymphorrhagia and tumor-nodemetastasis stage were important prognostic factors for OS of AEG patients,whereas the selection of surgical method between ADTR and RY was shown to be a similar prognostic factor for OS of AEG patients.CONCLUSION:ADTR by jejunal interposition presents similar rates of tumor recurrence,metastasis and longterm survival compared with classical reconstruction with RY esophagojejunostomy; however,it offers considerably improved near-term quality of life,especially in terms of early recovery and decreased reflux esophagitis. Thus,ADTR is recommended as a worthwhile digestive tract reconstruction method for Siewert types Ⅱ and Ⅲ AEG.展开更多
目的:系统评价康柏西普和雷珠单抗治疗视网膜静脉阻塞(RVO)继发黄斑水肿(ME)的疗效、安全性、经济性。方法:分别在万方数据库、中国生物医学文献服务系统、中国知网、Pubmed、The Cochrane Library Central Register of Controlled Tria...目的:系统评价康柏西普和雷珠单抗治疗视网膜静脉阻塞(RVO)继发黄斑水肿(ME)的疗效、安全性、经济性。方法:分别在万方数据库、中国生物医学文献服务系统、中国知网、Pubmed、The Cochrane Library Central Register of Controlled Trials(CENTRAL)、Google scholar等数据库收集自建库至2020-02-20关于康柏西普和雷珠单抗治疗RVO继发ME的对照研究,提取最佳矫正视力、黄斑中心凹视网膜厚度、不良反应发生情况、注射次数等主要结局指标进行系统评价,比较二者的效果。采用RevMan 5.3统计软件进行数据的分析。结果:共纳入16项研究,合计患者1337例。Meta分析结果提示,与雷珠单抗相比,康柏西普在采用1+PRN注射方案和治疗视网膜分支静脉阻塞(BRVO)继发ME患者时,对黄斑水肿的消退效果更明显,但二者注射次数无明显差异;与雷珠单抗相比,康柏西普在采用3+PRN注射方案和治疗视网膜中央静脉阻塞(CRVO)继发ME患者时,注射次数更少;康柏西普和雷珠单抗在视力改善和不良反应的发生方面无明显差异。结论:与雷珠单抗相比,康柏西普在不同的注射方案和不同的静脉阻塞类型治疗中体现出更优的效果,即更少的注射次数或更好的黄斑水肿消退效果。展开更多
The wheat canopy reflectance spectrum is affected by many internal and external factors such as diseases and growth stage. Separating the effects of disease stress on the crop from the observed mixed signals is crucia...The wheat canopy reflectance spectrum is affected by many internal and external factors such as diseases and growth stage. Separating the effects of disease stress on the crop from the observed mixed signals is crucial for increasing the precision of remote sensing monitoring of wheat stripe rust. The canopy spectrum of winter wheat infected by stripe rust was processed with the difference-in-differences(DID) algorithm used in econometrics. The monitoring accuracies of wheat stripe rust before and after processing with the DID algorithm were compared in the presence of various external factors, disease severity, and several simulated satellite sensors. The correlation between the normalized difference vegetation index processed by the DID algorithm(NDVI-DID) and the disease severity level(SL) increased in comparison with the NDVI before processing. The increase in precision in the natural disease area in the field in the presence of large differences in growth stage, growth, planting, and management of the crop was greater than that in the controlled experiment. For low disease levels(SL < 20%), the R2 of the regression of NDVI-DIDon SL was 38.8% higher than that of the NDVI and the root mean square error(RMSE) was reduced by 11.1%. The increase in precision was greater than that for the severe level(SL > 40%).According to the measured hyperspectral data, the spectral reflectance of three satellite sensor levels was simulated. The wide-band NDVI was calculated. Compared with the wide-band NDVI and vegetation indexes(VI) before DID processing, there were increases in the correlation between SL and the various types of VIS-DID, as well as in the correlation between SL and NDVI-DID. It is feasible to apply the DID algorithm to multispectral satellite data and diverse types of VISfor monitoring wheat stripe rust. Our results improve the quantification of independent effects of stripe rust infection on canopy reflectance spectrum,increase the precision of remote sensing monitoring of wheat stripe rust, and provide a reference for remote sensing monitoring of other crop diseases.展开更多
The corrosion and discharge performances of binary Mg−xLa(x=0.2−0.8,wt.%)alloys as anode materials for Mg-based batteries were evaluated.Microstructure,hydrogen evolution,mass loss,electrochemical behavior,and half-ce...The corrosion and discharge performances of binary Mg−xLa(x=0.2−0.8,wt.%)alloys as anode materials for Mg-based batteries were evaluated.Microstructure,hydrogen evolution,mass loss,electrochemical behavior,and half-cell discharge capabilities were characterized.The results show that the corrosion rate of the Mg matrix was decreased by alloying with La,and this could be attributed to the formation of a protective La2O3-containing film on the surface of the alloy.The Mg−0.2La alloy displayed the lowest corrosion rate,i.e.,2.4 mm/a in a 3.5 wt.%NaCl solution,Furthermore,the discharge performance of Mg−0.4La alloy was superior to that of pure Mg and other Mg−La alloys;this could be associated with the modified microstructure of the Mg−0.4La alloy,which decreased the self-corrosion and accelerated the detachment of the discharge products.展开更多
In order to improve the efficiency and stability of inverted three-dimensional(3D) or quasi-2D perovskite solar cells(PSCs) for future commercialization, exploring high efficient dopant-free polymer holetransporting m...In order to improve the efficiency and stability of inverted three-dimensional(3D) or quasi-2D perovskite solar cells(PSCs) for future commercialization, exploring high efficient dopant-free polymer holetransporting materials(HTMs) is still desired and meaningful. One simple and efficient way to achieve high performance dopant-free HTMs is to synthesize novel non-conjugated side-chain polymers via rational molecular design. In this work, N-(4-methoxyphenyl)-9,9-dimethyl-9H-fluoren-2-amine(FMeNPh) groups are introduced into the poly(N-vinylcarbazole)(PVK) side chains to afford two nonconjugated polymers PVCz-DFMeNPh and PVCz-FMeNPh as dopant-free HTMs in inverted quasi-2D PSCs. Benefited from the flexible properties of polyethylene backbone and excellent optoelectronic natures of FMeNPh side-chain groups, PVCz-DFMeNPh with more FMeNPh units exhibited excellent thermal stability, well-matched energy levels and improved charge mobility as compared to PTAA and PVCzFMeNPh. Moreover, the morphologies investigation of quasi-2D perovskite on PVCz-DFMeNPh shows more compact and homogeneous perovskite films than those on PTAA and PVCz-FMeNPh. As a result,the dopant-free PVCz-DFMeNPh based inverted quasi-2D PSCs deliver power conversion efficiency(PCE) up to 18.44% as well as negligible hysteresis and favorable long-term stability, which represents as excellent performance reported to date for inverted quasi-2D PSCs. The results demonstrate the great potentials of constructing non-conjugated side-chain polymer HTMs based on phenylfluorenamine-func tionalized PVK for the development of high efficient and stable inverted 3D or quasi-2D PSCs.展开更多
Recently,analog visual transmission has attracted considerable attention owing to its graceful performance degradation for various wireless channels.In this study,we propose a novel analog visual communications system...Recently,analog visual transmission has attracted considerable attention owing to its graceful performance degradation for various wireless channels.In this study,we propose a novel analog visual communications system,named DVCast,in which an image denoising algorithm is used to fully utilize spatial correlation;moreover,the variable block size Discrete Cosine Transform(DCT)is used to preserve more correlation information in an image.Obviously,there is a tradeoff between system performance and computing complexity.Therefore,to improve the real-time performance of the proposed system,implementation of Block Matching with 3D filtering(BM3D)and DCT by Graphics Processing Units(GPUs)is introduced.According to DCT block size,i.e.,88,1616,and 3232,the schemes DVCast8,DVCast16,and DVCast32,respectively,are designed and implemented.Simulations show that DVCast with larger block size achieves better gain and visual quality than reference schemes.Moreover,it requires less computing time.DVCast32 outperforms conventional digital schemes by approximately 3.51 dB and achieves a 1.12 dB gain over state-of-the-art reference schemes.Furthermore,the analysis shows that DVCast can reduce overhead by at least 75%.展开更多
Recently studies found that TRPC3 and TRPC6 played an important role in cardiovascular disease. Hypertension, as a cardiovascular disease causing the highest morbidity and mortality, has close relationship with the ex...Recently studies found that TRPC3 and TRPC6 played an important role in cardiovascular disease. Hypertension, as a cardiovascular disease causing the highest morbidity and mortality, has close relationship with the expressions of TRPC3 and TRPC6. Unbalanced calcium homeostasis is the major factor of pathogenesis of hypertension. Changes of intracellular calcium concentration depend on calcium transmembrane transportation, intracellular calcium store releasing and other processes. TRPC3, TRPC6 molecules, as non-selective cation channels on the cell membranes, are involved in the processes. This review illustrated the functions of TRPC3 and TRPC6 on myocardial cells, smooth muscle cells and inflammatory cells in the development of hypertension, and the effects of drugs like sildenafil to provide a new way for the prevention and treatment of hypertension.展开更多
This paper investigates the modal properties of semiconductor lasers operating in the strong-feedback regime. Analytical expressions are developed based on an iterative travelling-wave model, which enable a complete a...This paper investigates the modal properties of semiconductor lasers operating in the strong-feedback regime. Analytical expressions are developed based on an iterative travelling-wave model, which enable a complete and quantitative description of a compound cavity mode in its steady state. Additional information is provided about the physical inside into a compound laser system, such as a bifurcation diagram of the compound cavity modes for full variation range （from 0 to 1） of the external reflection coefficient and a more general shape for the diagram of photon density versus mode phase - this latter will reduce to the classical ＂ellipse＂ in the weak-feedback regime. It is shown that in the strong-feedback regime, a feedback laser is characterized by a small mode number and a high density of photons. This behavior confirms previous experimental observations, showing that beyond the coherence-collapse regime, the compound laser system could be re-stabilized, and that as a result power-enhanced low-noise stable laser operation with quasi-uniform pulsation is possible with external-mirror reflectivity close to 1. Moreover, it is also shown that for a compound system operating in the strong-feedback regime, an anti-reflection treatment of a laser can significantly reduce its current threshold, and that in the absence of this treatment excitation of a minimum-linewidth mode with higher output power would be possible inside such a system. Finally, it is shown that in the weak-feedback regime except for a phase shift the iterative travelling-wave model will reduce to the Lang-Kobayashi model in cases where the product of the feedback rate and the internal round-trip time is much less than unity （that would mean in situations of as-cleaved lasers）.展开更多
This paper investigates the steady-state behavior of a semiconductor laser subject to arbitrary levels of external optical feedback by means of an iterative travelling-wave (ITW) model. Analytical expressions are deve...This paper investigates the steady-state behavior of a semiconductor laser subject to arbitrary levels of external optical feedback by means of an iterative travelling-wave (ITW) model. Analytical expressions are developed based on an iterative equation. We show that, as in good agreement with previous work, in the weak-feedback regime of operation except for a phase shift the ITW model will be simplified to the Lang-Kobayashi (LK) model, and that in the case where this phase shift is equal to zero the ITW model is identical to the LK model. The present work is of use in particular for distinguishing the coherence-collapse regime from the strong-feedback regime where low-intensity-noise and narrow-linewidth laser operation would be possible at high feedback levels with re-stabilization of the compound laser system.展开更多
Three-dimensional(3D)bioprinting,specifically direct ink writing(DIW)capable of printing biologically active substances such as growth factors or drugs under low-temperature conditions,is an emerging di-rection in bon...Three-dimensional(3D)bioprinting,specifically direct ink writing(DIW)capable of printing biologically active substances such as growth factors or drugs under low-temperature conditions,is an emerging di-rection in bone tissue engineering.However,limited by the bio-ink mobility and the poor resolution of this printing technology,the lateral pores of current crisscross-stacked scaffolds printed through DIW tend to clog and are inimical to bone growth.Therefore,it is critical to develop DIW printed biologi-cal scaffold structure with high mechanical strength,porosity,and biocompatibility performance.Herein,patterned polylactic acid(PLA)/polycaprolactone(PCL)/nano-hydroxyapatite(n-HA)based scaffold was printed through DIW technological and rolled-up for properties characterization,cytocompatibility test,and bone repair experiment.The result not only shows that the hexagonal patterned scaffolds are me-chanically strong with porosity,but also demonstrated that the hierarchical pore structure formed during rolled-up has the potential to address the clogging problem and stimulates bone growth and repair.展开更多
π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance a...π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance and stability of deep-blue polymer light-emitting diodes(PLEDs).Herein,considerate of“defect”carbazole(Cz)electromers in poly(N-vinylcarbazole)(PVK),a series of fluorene units are introduced into pendant segments(PVCz-DMeF,PVCz-FMeNPh and PVCz-DFMeNPh)to suppress the strongπ-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs.Compared to PVCz-FMeNPh and PVCz-DFMeNPh,PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission,completely similar to its single pendant chromophore,confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments.Therefore,PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity(0.17,0.08),associated with extremely weak defect emission at 600∼700nm(induced by carbazole electromers).Finally,PLEDs based on PVCz-DMeF/F8BT blended films(1:1)also present the high maximum luminance(Lmax)of 6261 cd/m2 and current efficiency(CE_(max))of 2.03 cd/A,confirmed slightly trapped sites formation.Therefore,precisely control the arrangement and packing model of pendant units inπ-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.展开更多
Heterostructure metals as a new class of materials can effectively break the traditional strength–ductility trade-off dilemma. In this study, the extruded sheet with the small extrusion ratio(ER) of 3.9(ER3.9)present...Heterostructure metals as a new class of materials can effectively break the traditional strength–ductility trade-off dilemma. In this study, the extruded sheet with the small extrusion ratio(ER) of 3.9(ER3.9)presented a heterogeneous lamella structure(HLS) and texture, where the fine dynamical recrystallized(DRXed) grains formed a random texture and coarse un-DRXed grains exhibited a strong basal texture.The ER3.9 sample presented an excellent combination of strength and ductility. The texture strengthening in coarse grains and hetero-deformation induced(HDI) strengthening contributed to the enhanced strength of the ER3.9 sample besides grain refinement. The improving ductility mainly stems from the weakened texture in fine grains. Interestingly, in coarse grains, the strong basal texture, the occurrence of cross slip, low stacking fault energy(SFE), and dislocation pinned by precipitates weaken the HDI hardening effect. While the traditional dislocation hardening mainly generated by fine grains dominates overall strain hardening. Meanwhile, the activation of non-basal slips, especially pyramidal <c + a> slip,and the generation of cross slips in fine grains benefit for coordinating plastic deformation. The ability for coordinate plastic deformation in fine grains is higher than that of coarse grains, which was confirmed by the digital image correlation technology. This work will promote the development of the heterogeneous theory in textured Mg alloys.展开更多
Heterogeneous metals and alloys are a new class of materials with superior mechanical properties.In this paper,we engineered sandwich-structured pure aluminum laminates composed of middle coarse-grained layer and oute...Heterogeneous metals and alloys are a new class of materials with superior mechanical properties.In this paper,we engineered sandwich-structured pure aluminum laminates composed of middle coarse-grained layer and outer fine-grained layer via extrusion,rolling and annealing.By controlling the post-annealing regimes,a larger degree of microstructure heterogeneities such as boundary spacing,misorientation and texture across the hetero-interface were obtained,which resulted in obvious mechanical differences.Tensile tests indicated that the 300℃/30 min annealed laminates enabled a relatively high tensile ductility while simultaneously retaining a high strength,which was better than prediction by the rule-of-mixture.To explain the reasons behind it,the evolution of geometrically necessary dislocations and strain gradient at the hetero-interface zone were detected using in-situ tension and microscopic digital image correlation technique.It was found that with the increasing applied strain,a significant strain gradient was developed near the interface,which was accommodated by geometrically necessary dislocations,thereby contributing to higher hetero-deformation induced(HDI)strengthening and hardening.展开更多
We demonstrate a simple,effective and feasible method to address the shrinkage of Poly(lactic-co-glycolic acid)(PLGA)through a core-shell structure fiber strategy.The results revealed that introducing size-stable poly...We demonstrate a simple,effective and feasible method to address the shrinkage of Poly(lactic-co-glycolic acid)(PLGA)through a core-shell structure fiber strategy.The results revealed that introducing size-stable poly-caprolactone(PCL)as the core fiber significantly improved the PLGA-based fibrous scaffold’s dimensional maintenance.We further utilized fish collagen to modify the PLGA shell layer(PFC)of coaxial fibers and loaded baicalin(BA)into the PCL core layer(PCL-BA)to endow fibrous scaffold with more functional biological cues.The PFC/PCL-BA fibrous scaffold promoted the osteogenic differentiation of bone mesenchymal stem cells and stimulated the RAW264.7 cells to polarize into a pro-reparative phenotype.Importantly,the in vivo study demonstrated that the PFC/PCL-BA scaffold could regulate inflammation and osteoclast differentiation,favor neovascularization and bone formation.This work tactfully combined PLGA and PCL to establish a drug release platform based on the core-shell fibrous scaffold for vascularized bone regeneration.展开更多
High-entropy alloys are suitable for use as a binder for cemented carbides duo to outstanding mechanical, oxidation and wear behavior. Therefore, high-entropy alloy was selected to replace Co and Ni metal bond in this...High-entropy alloys are suitable for use as a binder for cemented carbides duo to outstanding mechanical, oxidation and wear behavior. Therefore, high-entropy alloy was selected to replace Co and Ni metal bond in this study. The results of X-ray diffraction analysis show that CoCrNiCuMn high-entropy alloy is stabilized in the cemented carbide system. Scanning electron microscope（SEM） fractural morphologies of the cemented carbides added with CoCrNiCuMn show that CoCrNiCuMn distributes in grain boundaries, and the grains are bound tightly together. Furthermore, SEM fractural morphologies of the cemented carbides with 5 wt%, 7 wt%, and 10 wt% CoCrNiCuMn show that CoCrNiCuMn slows the growth of grains, which effectively binders the grains, prevents the generation and propagation of cracks, and finally, greatly improves the toughness of the cemented carbides.According to the results observed in the cemented carbides containing different amounts of CoCrNiCuMn, the hardness level gradually increases with the amount of CoCrNiCuMn; however, a reverse trend is seen in the toughness level. The cemented carbide with 10 wt% CoCrNiCuMn shows the highest toughness value of 7.05 MPa·m^1/2.展开更多
Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome ...Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome in Escherich＆ coli, we conducted ribosome profiling in parallel with RNA-Seq to investigate the alterations in transcription and translation efficiency when E. coli cells were exposed to a mild heat stress （from 30 ~C to 45 ~C）. While general changes in ribosome foot- prints correlate with the changes of mRNA transcripts upon heat stress, a number of genes show differential changes at the transcription and translation levels. Translation efficiency of a few genes that are related to environment stimulus response is up-regulated, and in contrast, some genes func- tioning in mRNA translation and amino acid biosynthesis are down-regulated at the translation level in response to heat stress. Moreover, our ribosome occupancy data suggest that in generalribosomes accumulate remarkably in the starting regions of ORFs upon heat stress. This study pro- vides additional insights into bacterial gene expression in response to heat stress, and suggests the presence of stress-induced but yet-to-be characterized cellular regulatory mechanisms of gene expression at translation level.展开更多
基金supported by the National Key Research Center and Development Program of the 14th Five-Year Plan,China(No.2022YFC2905105)National Natural Science Foundation of China(Nos.52122406 and 52004337)+2 种基金Hunan High-tech Industry Technology Innovation Leading Plan,China(No.2022GK4056)Hunan Innovative Province Construction Special Project,China(No.2020RC3001)Hunan Postgraduate Research and Innovation Project,China(No.CX20220200).
文摘Flotation separation of calcite from fluorite is a challenge on low-grade fluorite flotation that limits the recovery and purity of fluorite concentrate.A new acid leaching–flotation process for fluorite is proposed in this work.This innovative process raised the fluor-ite’s grade to 97.26wt%while producing nanoscale calcium carbonate from its leachate,which contained plenty of calcium ions.On the production of nanoscale calcium carbonate,the impacts of concentration,temperature,and titration rate were examined.By modifying the process conditions and utilizing crystal conditioning agents,calcite-type and amorphous calcium carbonates with corresponding particle sizes of 1.823 and 1.511μm were produced.The influence of the impurity ions Mn^(2+),Mg^(2+),and Fe^(3+)was demonstrated to reduce the particle size of nanoscale calcium carbonate and make crystal shape easier to manage in the fluorite leach solution system compared with the calcium chloride solution.The combination of the acid leaching–flotation process and the nanoscale calcium carbonate preparation method improved the grade of fluorite while recovering calcite resources,thus presenting a novel idea for the effective and clean usage of low-quality fluorite resources with embedded microfine particles.
文摘This paper investigates rate adaptation schemes for decoding-and-forward (DF) relay system based on random projections codes (RPC). We consider a classic three node relay system model, where relay node performs on half-duplex mode. Then, we give out receiving diversity relay scheme and coding diversity relay scheme, and present their jointly decoding methods. Furthermore, we discuss the performance of the two schemes with different power allocation coefficients. Simulations show that our relay schemes can achieve different gain with the help of relay node. And, we should allocate power to source node to just guarantee relay node can decode successfully, and allocate remain power to relay node as far as possible. In this way, this DF relay system not only achieves diversity gain, but also achieves higher and smooth spectrum efficiency.
基金Supported by Grants from Sichuan Provincial Department of Education Research Project,No.14ZA0192National Natural Science Foundation of China,No.30700773,No.81070378,and No.81270561
文摘AIM:To explore a reasonable method of digestive tract reconstruction,namely,antrum-preserving double-tract reconstruction(ADTR),for patients with adenocarcinoma of the esophagogastric junction(AEG) and to assess its efficacy and safety in terms of longterm survival,complications,morbidity and mortality.METHODS:A total of 55 cases were retrospectively collected,including 18 cases undergoing ADTR and 37 cases of Roux-en-Y reconstruction(RY) for AEG(Siewert types Ⅱ and Ⅲ) at North Sichuan Medical College. The cases were divided into two groups. The clinicopathological characteristics,perioperative outcomes,postoperative complications,morbidity and overall survival(OS) were compared for the two different reconstruction methods.RESULTS:Basic characteristics including sex,age,body mass index(BMI),Siewert type,p T status,p N stage,and lymph node metastasis were similar in the two groups. No significant differences were found between the two groups in terms of perioperative outcomes(including the length of postoperative hospital stay,operating time,and intraoperative blood loss) and postoperative complications(consisting of anastomosis-related complications,wound infection,respiratory infection,pleural effusion,lymphorrhagia,and cholelithiasis). For the ADTR group,perioperativerecovery indexes such as time to first flatus(P = 0.002) and time to resuming a liquid diet(P = 0.001) were faster than those for the RY group. Moreover,the incidence of reflux esophagitis was significantly decreased compared with the RY group(P = 0.048). The postoperative morbidity and mortality rates for overall postoperative complications and the rates of tumor recurrence and metastasis were not significantly different between the two groups. Survival curves plotted using the Kaplan-Meier method and compared by log-rank test demonstrated similar outcomes for the ADTR and RY groups. Multivariate analysis of significantly different factors that presented as covariates on Cox regression analysis to assess the survival and recurrence among AEG patients showed that age,gender,BMI,pleural effusion,time to resuming a liquid diet,lymphorrhagia and tumor-nodemetastasis stage were important prognostic factors for OS of AEG patients,whereas the selection of surgical method between ADTR and RY was shown to be a similar prognostic factor for OS of AEG patients.CONCLUSION:ADTR by jejunal interposition presents similar rates of tumor recurrence,metastasis and longterm survival compared with classical reconstruction with RY esophagojejunostomy; however,it offers considerably improved near-term quality of life,especially in terms of early recovery and decreased reflux esophagitis. Thus,ADTR is recommended as a worthwhile digestive tract reconstruction method for Siewert types Ⅱ and Ⅲ AEG.
文摘目的:系统评价康柏西普和雷珠单抗治疗视网膜静脉阻塞(RVO)继发黄斑水肿(ME)的疗效、安全性、经济性。方法:分别在万方数据库、中国生物医学文献服务系统、中国知网、Pubmed、The Cochrane Library Central Register of Controlled Trials(CENTRAL)、Google scholar等数据库收集自建库至2020-02-20关于康柏西普和雷珠单抗治疗RVO继发ME的对照研究,提取最佳矫正视力、黄斑中心凹视网膜厚度、不良反应发生情况、注射次数等主要结局指标进行系统评价,比较二者的效果。采用RevMan 5.3统计软件进行数据的分析。结果:共纳入16项研究,合计患者1337例。Meta分析结果提示,与雷珠单抗相比,康柏西普在采用1+PRN注射方案和治疗视网膜分支静脉阻塞(BRVO)继发ME患者时,对黄斑水肿的消退效果更明显,但二者注射次数无明显差异;与雷珠单抗相比,康柏西普在采用3+PRN注射方案和治疗视网膜中央静脉阻塞(CRVO)继发ME患者时,注射次数更少;康柏西普和雷珠单抗在视力改善和不良反应的发生方面无明显差异。结论:与雷珠单抗相比,康柏西普在不同的注射方案和不同的静脉阻塞类型治疗中体现出更优的效果,即更少的注射次数或更好的黄斑水肿消退效果。
基金supported by the National Natural Science Foundation of China (42171394, 41601467)。
文摘The wheat canopy reflectance spectrum is affected by many internal and external factors such as diseases and growth stage. Separating the effects of disease stress on the crop from the observed mixed signals is crucial for increasing the precision of remote sensing monitoring of wheat stripe rust. The canopy spectrum of winter wheat infected by stripe rust was processed with the difference-in-differences(DID) algorithm used in econometrics. The monitoring accuracies of wheat stripe rust before and after processing with the DID algorithm were compared in the presence of various external factors, disease severity, and several simulated satellite sensors. The correlation between the normalized difference vegetation index processed by the DID algorithm(NDVI-DID) and the disease severity level(SL) increased in comparison with the NDVI before processing. The increase in precision in the natural disease area in the field in the presence of large differences in growth stage, growth, planting, and management of the crop was greater than that in the controlled experiment. For low disease levels(SL < 20%), the R2 of the regression of NDVI-DIDon SL was 38.8% higher than that of the NDVI and the root mean square error(RMSE) was reduced by 11.1%. The increase in precision was greater than that for the severe level(SL > 40%).According to the measured hyperspectral data, the spectral reflectance of three satellite sensor levels was simulated. The wide-band NDVI was calculated. Compared with the wide-band NDVI and vegetation indexes(VI) before DID processing, there were increases in the correlation between SL and the various types of VIS-DID, as well as in the correlation between SL and NDVI-DID. It is feasible to apply the DID algorithm to multispectral satellite data and diverse types of VISfor monitoring wheat stripe rust. Our results improve the quantification of independent effects of stripe rust infection on canopy reflectance spectrum,increase the precision of remote sensing monitoring of wheat stripe rust, and provide a reference for remote sensing monitoring of other crop diseases.
基金the financial supports from the National Key Research and Development Program of China(Nos.2016YFB-0101700,2016YFB0301104)the National Natural Science Foundation of China(Nos.U1764253,51971044,U1910213)+3 种基金the National Defense Basic Scientific Research Program of Chinathe Chong-qing Science and Technology Commission,China(Nos.cstc2017zdcy-zdzxX0006,cstc2018jszx-cyzdx0082)the Chongqing Scientific&Technological Talents Program,China(No.KJXX-2017002)Qinghai Scientific&Technological Program,China(No.2018-GX-A1).
文摘The corrosion and discharge performances of binary Mg−xLa(x=0.2−0.8,wt.%)alloys as anode materials for Mg-based batteries were evaluated.Microstructure,hydrogen evolution,mass loss,electrochemical behavior,and half-cell discharge capabilities were characterized.The results show that the corrosion rate of the Mg matrix was decreased by alloying with La,and this could be attributed to the formation of a protective La2O3-containing film on the surface of the alloy.The Mg−0.2La alloy displayed the lowest corrosion rate,i.e.,2.4 mm/a in a 3.5 wt.%NaCl solution,Furthermore,the discharge performance of Mg−0.4La alloy was superior to that of pure Mg and other Mg−La alloys;this could be associated with the modified microstructure of the Mg−0.4La alloy,which decreased the self-corrosion and accelerated the detachment of the discharge products.
基金financially supported by the National Key Research and Development Program of China (2018YFB0406704)the National Natural Science Foundation of China (61974066, 61725502, 61634001)+3 种基金the Major Research Plan of the National Natural Science Foundation of China (91733302)the fund for Talented of Nanjing Tech University (201983)the Major Program of Natural Science Research of Jiangsu Higher Education Institutions of China (18KJA510002)the Synergetic Innovation Center for Organic Electronics and Information Displays。
文摘In order to improve the efficiency and stability of inverted three-dimensional(3D) or quasi-2D perovskite solar cells(PSCs) for future commercialization, exploring high efficient dopant-free polymer holetransporting materials(HTMs) is still desired and meaningful. One simple and efficient way to achieve high performance dopant-free HTMs is to synthesize novel non-conjugated side-chain polymers via rational molecular design. In this work, N-(4-methoxyphenyl)-9,9-dimethyl-9H-fluoren-2-amine(FMeNPh) groups are introduced into the poly(N-vinylcarbazole)(PVK) side chains to afford two nonconjugated polymers PVCz-DFMeNPh and PVCz-FMeNPh as dopant-free HTMs in inverted quasi-2D PSCs. Benefited from the flexible properties of polyethylene backbone and excellent optoelectronic natures of FMeNPh side-chain groups, PVCz-DFMeNPh with more FMeNPh units exhibited excellent thermal stability, well-matched energy levels and improved charge mobility as compared to PTAA and PVCzFMeNPh. Moreover, the morphologies investigation of quasi-2D perovskite on PVCz-DFMeNPh shows more compact and homogeneous perovskite films than those on PTAA and PVCz-FMeNPh. As a result,the dopant-free PVCz-DFMeNPh based inverted quasi-2D PSCs deliver power conversion efficiency(PCE) up to 18.44% as well as negligible hysteresis and favorable long-term stability, which represents as excellent performance reported to date for inverted quasi-2D PSCs. The results demonstrate the great potentials of constructing non-conjugated side-chain polymer HTMs based on phenylfluorenamine-func tionalized PVK for the development of high efficient and stable inverted 3D or quasi-2D PSCs.
基金the National Nature Science Foundation of China(Nos.61601128,61762053)the Science and Technology Plan Funding of Jiangxi Province of China(No.20151BBE50076)+1 种基金the Research Foundations of Education Bureau of Jiangxi Province(Nos.GJJ151001,GJJ150984)the Open Project Funding of Key Laboratory of Jiangxi Province for Numerical Simulation and Emulation Techniques,China.
文摘Recently,analog visual transmission has attracted considerable attention owing to its graceful performance degradation for various wireless channels.In this study,we propose a novel analog visual communications system,named DVCast,in which an image denoising algorithm is used to fully utilize spatial correlation;moreover,the variable block size Discrete Cosine Transform(DCT)is used to preserve more correlation information in an image.Obviously,there is a tradeoff between system performance and computing complexity.Therefore,to improve the real-time performance of the proposed system,implementation of Block Matching with 3D filtering(BM3D)and DCT by Graphics Processing Units(GPUs)is introduced.According to DCT block size,i.e.,88,1616,and 3232,the schemes DVCast8,DVCast16,and DVCast32,respectively,are designed and implemented.Simulations show that DVCast with larger block size achieves better gain and visual quality than reference schemes.Moreover,it requires less computing time.DVCast32 outperforms conventional digital schemes by approximately 3.51 dB and achieves a 1.12 dB gain over state-of-the-art reference schemes.Furthermore,the analysis shows that DVCast can reduce overhead by at least 75%.
文摘Recently studies found that TRPC3 and TRPC6 played an important role in cardiovascular disease. Hypertension, as a cardiovascular disease causing the highest morbidity and mortality, has close relationship with the expressions of TRPC3 and TRPC6. Unbalanced calcium homeostasis is the major factor of pathogenesis of hypertension. Changes of intracellular calcium concentration depend on calcium transmembrane transportation, intracellular calcium store releasing and other processes. TRPC3, TRPC6 molecules, as non-selective cation channels on the cell membranes, are involved in the processes. This review illustrated the functions of TRPC3 and TRPC6 on myocardial cells, smooth muscle cells and inflammatory cells in the development of hypertension, and the effects of drugs like sildenafil to provide a new way for the prevention and treatment of hypertension.
文摘This paper investigates the modal properties of semiconductor lasers operating in the strong-feedback regime. Analytical expressions are developed based on an iterative travelling-wave model, which enable a complete and quantitative description of a compound cavity mode in its steady state. Additional information is provided about the physical inside into a compound laser system, such as a bifurcation diagram of the compound cavity modes for full variation range （from 0 to 1） of the external reflection coefficient and a more general shape for the diagram of photon density versus mode phase - this latter will reduce to the classical ＂ellipse＂ in the weak-feedback regime. It is shown that in the strong-feedback regime, a feedback laser is characterized by a small mode number and a high density of photons. This behavior confirms previous experimental observations, showing that beyond the coherence-collapse regime, the compound laser system could be re-stabilized, and that as a result power-enhanced low-noise stable laser operation with quasi-uniform pulsation is possible with external-mirror reflectivity close to 1. Moreover, it is also shown that for a compound system operating in the strong-feedback regime, an anti-reflection treatment of a laser can significantly reduce its current threshold, and that in the absence of this treatment excitation of a minimum-linewidth mode with higher output power would be possible inside such a system. Finally, it is shown that in the weak-feedback regime except for a phase shift the iterative travelling-wave model will reduce to the Lang-Kobayashi model in cases where the product of the feedback rate and the internal round-trip time is much less than unity （that would mean in situations of as-cleaved lasers）.
文摘This paper investigates the steady-state behavior of a semiconductor laser subject to arbitrary levels of external optical feedback by means of an iterative travelling-wave (ITW) model. Analytical expressions are developed based on an iterative equation. We show that, as in good agreement with previous work, in the weak-feedback regime of operation except for a phase shift the ITW model will be simplified to the Lang-Kobayashi (LK) model, and that in the case where this phase shift is equal to zero the ITW model is identical to the LK model. The present work is of use in particular for distinguishing the coherence-collapse regime from the strong-feedback regime where low-intensity-noise and narrow-linewidth laser operation would be possible at high feedback levels with re-stabilization of the compound laser system.
基金supported by the China NSFC project(No.32171338)the Key Science and Technology Special Project of Sichuan Province(No.2020ZDZX0008)the Innovation and Reform Project of Postgraduate Education of Sichuan University in 2021,and the Experimental Technology Research Project of Sichuan University(No.SCU221099).
文摘Three-dimensional(3D)bioprinting,specifically direct ink writing(DIW)capable of printing biologically active substances such as growth factors or drugs under low-temperature conditions,is an emerging di-rection in bone tissue engineering.However,limited by the bio-ink mobility and the poor resolution of this printing technology,the lateral pores of current crisscross-stacked scaffolds printed through DIW tend to clog and are inimical to bone growth.Therefore,it is critical to develop DIW printed biologi-cal scaffold structure with high mechanical strength,porosity,and biocompatibility performance.Herein,patterned polylactic acid(PLA)/polycaprolactone(PCL)/nano-hydroxyapatite(n-HA)based scaffold was printed through DIW technological and rolled-up for properties characterization,cytocompatibility test,and bone repair experiment.The result not only shows that the hexagonal patterned scaffolds are me-chanically strong with porosity,but also demonstrated that the hierarchical pore structure formed during rolled-up has the potential to address the clogging problem and stimulates bone growth and repair.
基金supported by the National Natural Science Foundation of China(Nos.22105099 and 61874053)Natural Science Foundation of Jiangsu Province(No.BK20200700)+2 种基金the China Postdoctoral Science Foundation(No.2022M711591)the open research fund from Anhui Province Key Laboratory of Optoelectronic Materials Science and Technology(No.OMST202101)the State Key Laboratory of Luminescent Materials and Devices(South China University of Technology).
文摘π-Electron coupling of pendant conjugated segment inπ-stacked semiconducting polymers always causes the formation of defect trapped sites and further quenched high-band excitons,which is harmful to the performance and stability of deep-blue polymer light-emitting diodes(PLEDs).Herein,considerate of“defect”carbazole(Cz)electromers in poly(N-vinylcarbazole)(PVK),a series of fluorene units are introduced into pendant segments(PVCz-DMeF,PVCz-FMeNPh and PVCz-DFMeNPh)to suppress the strongπ-electron coupling of pendant Cz units and enhance radiative transition toward fabricating sable PLEDs.Compared to PVCz-FMeNPh and PVCz-DFMeNPh,PVCz-DMeF spin-coated films show a relatively efficient deep-blue emission,completely similar to its single pendant chromophore,confirmed an extremely weak charge-transfer and electron coupling between adjacent pendant segments.Therefore,PLEDs based on PVCz-DMeF present stable and deep-blue emission with a high color purity(0.17,0.08),associated with extremely weak defect emission at 600∼700nm(induced by carbazole electromers).Finally,PLEDs based on PVCz-DMeF/F8BT blended films(1:1)also present the high maximum luminance(Lmax)of 6261 cd/m2 and current efficiency(CE_(max))of 2.03 cd/A,confirmed slightly trapped sites formation.Therefore,precisely control the arrangement and packing model of pendant units inπ-stacked polymer is an essential prerequisite for building efficient and stable emitter for optoelectronic devices.
基金supported by the National Natural Science Foundation of China(Nos.52071035 and U1764253).
文摘Heterostructure metals as a new class of materials can effectively break the traditional strength–ductility trade-off dilemma. In this study, the extruded sheet with the small extrusion ratio(ER) of 3.9(ER3.9)presented a heterogeneous lamella structure(HLS) and texture, where the fine dynamical recrystallized(DRXed) grains formed a random texture and coarse un-DRXed grains exhibited a strong basal texture.The ER3.9 sample presented an excellent combination of strength and ductility. The texture strengthening in coarse grains and hetero-deformation induced(HDI) strengthening contributed to the enhanced strength of the ER3.9 sample besides grain refinement. The improving ductility mainly stems from the weakened texture in fine grains. Interestingly, in coarse grains, the strong basal texture, the occurrence of cross slip, low stacking fault energy(SFE), and dislocation pinned by precipitates weaken the HDI hardening effect. While the traditional dislocation hardening mainly generated by fine grains dominates overall strain hardening. Meanwhile, the activation of non-basal slips, especially pyramidal <c + a> slip,and the generation of cross slips in fine grains benefit for coordinating plastic deformation. The ability for coordinate plastic deformation in fine grains is higher than that of coarse grains, which was confirmed by the digital image correlation technology. This work will promote the development of the heterogeneous theory in textured Mg alloys.
基金supported by the National Natural Science Foundation of China(Nos.52071035 and U1764253)。
文摘Heterogeneous metals and alloys are a new class of materials with superior mechanical properties.In this paper,we engineered sandwich-structured pure aluminum laminates composed of middle coarse-grained layer and outer fine-grained layer via extrusion,rolling and annealing.By controlling the post-annealing regimes,a larger degree of microstructure heterogeneities such as boundary spacing,misorientation and texture across the hetero-interface were obtained,which resulted in obvious mechanical differences.Tensile tests indicated that the 300℃/30 min annealed laminates enabled a relatively high tensile ductility while simultaneously retaining a high strength,which was better than prediction by the rule-of-mixture.To explain the reasons behind it,the evolution of geometrically necessary dislocations and strain gradient at the hetero-interface zone were detected using in-situ tension and microscopic digital image correlation technique.It was found that with the increasing applied strain,a significant strain gradient was developed near the interface,which was accommodated by geometrically necessary dislocations,thereby contributing to higher hetero-deformation induced(HDI)strengthening and hardening.
基金supported by the National Key Research and Development Program of China(No.2016YFA0201703/2016YFA0201700)the Key R&D Project of Sichuan Science and Technology Plan(2021YFS0030).
文摘We demonstrate a simple,effective and feasible method to address the shrinkage of Poly(lactic-co-glycolic acid)(PLGA)through a core-shell structure fiber strategy.The results revealed that introducing size-stable poly-caprolactone(PCL)as the core fiber significantly improved the PLGA-based fibrous scaffold’s dimensional maintenance.We further utilized fish collagen to modify the PLGA shell layer(PFC)of coaxial fibers and loaded baicalin(BA)into the PCL core layer(PCL-BA)to endow fibrous scaffold with more functional biological cues.The PFC/PCL-BA fibrous scaffold promoted the osteogenic differentiation of bone mesenchymal stem cells and stimulated the RAW264.7 cells to polarize into a pro-reparative phenotype.Importantly,the in vivo study demonstrated that the PFC/PCL-BA scaffold could regulate inflammation and osteoclast differentiation,favor neovascularization and bone formation.This work tactfully combined PLGA and PCL to establish a drug release platform based on the core-shell fibrous scaffold for vascularized bone regeneration.
基金financially supported by the Hebei Province Natural Science Foundation (No.E2016203425)
文摘High-entropy alloys are suitable for use as a binder for cemented carbides duo to outstanding mechanical, oxidation and wear behavior. Therefore, high-entropy alloy was selected to replace Co and Ni metal bond in this study. The results of X-ray diffraction analysis show that CoCrNiCuMn high-entropy alloy is stabilized in the cemented carbide system. Scanning electron microscope（SEM） fractural morphologies of the cemented carbides added with CoCrNiCuMn show that CoCrNiCuMn distributes in grain boundaries, and the grains are bound tightly together. Furthermore, SEM fractural morphologies of the cemented carbides with 5 wt%, 7 wt%, and 10 wt% CoCrNiCuMn show that CoCrNiCuMn slows the growth of grains, which effectively binders the grains, prevents the generation and propagation of cracks, and finally, greatly improves the toughness of the cemented carbides.According to the results observed in the cemented carbides containing different amounts of CoCrNiCuMn, the hardness level gradually increases with the amount of CoCrNiCuMn; however, a reverse trend is seen in the toughness level. The cemented carbide with 10 wt% CoCrNiCuMn shows the highest toughness value of 7.05 MPa·m^1/2.
基金supported by the National Natural Science Foundation of China(Grant Nos.31630087,31422016,and 31470722 to NGGrant Nos.31671381 and 91540109 to XY)
文摘Heat shock response is a classical stress-induced regulatory system in bacteria, character- ized by extensive transcriptional reprogramming. To compare the impact of heat stress on the tran- scriptome and translatome in Escherich＆ coli, we conducted ribosome profiling in parallel with RNA-Seq to investigate the alterations in transcription and translation efficiency when E. coli cells were exposed to a mild heat stress （from 30 ~C to 45 ~C）. While general changes in ribosome foot- prints correlate with the changes of mRNA transcripts upon heat stress, a number of genes show differential changes at the transcription and translation levels. Translation efficiency of a few genes that are related to environment stimulus response is up-regulated, and in contrast, some genes func- tioning in mRNA translation and amino acid biosynthesis are down-regulated at the translation level in response to heat stress. Moreover, our ribosome occupancy data suggest that in generalribosomes accumulate remarkably in the starting regions of ORFs upon heat stress. This study pro- vides additional insights into bacterial gene expression in response to heat stress, and suggests the presence of stress-induced but yet-to-be characterized cellular regulatory mechanisms of gene expression at translation level.
