Comparison of Properties of Bastnasite and Fluorocarbonate Rare-earth Polishing Powders

By means of DTA TG, XRD, SEM etc ., the particles configuration, crystal structure, chemical composition and other physical properties of bastnasite rare earth polishing powder and fluorocarbonate rare earth polishing powder were comparatively analyzed. The mechanism of the performance differences between two kinds of polishing powders was also investigated.

Integrated global analysis in spider flowers illuminates features underlying the evolution and maintenance of C_(4) photosynthesis

The carbon concentrating mechanism—C_(4) photosynthesis—represents a classic example of convergent evolution,but how this important trait originated and evolved remains largely enigmatic.The spider flower Gynandropsis gynandra is a valuable leafy vegetable crop and medicinal plant that has also been recognized as a C_(4) model species.Here we present a high-quality chromosome-scale annotated genome assembly of G.gynandra through a combination of Oxford Nanopore Technology(ONT),HiFi and Hi-C technology.The 17 super-scaffolds cover 98.66% of the estimated genome(997.61 Mb),with a contig N50 of 11.43 Mb and a scaffold N50 of 51.02 Mb.Repetitive elements occupy up to 71.91% of its genome,and over half are long terminal repeat retrotransposons(LTR-RTs)derived from recent bursts,contributing to genome size expansion.Strikingly,LTR-RT explosion also played a critical role in C_(4) evolution by altering expression features of photosynthesis-associated genes via preferential insertion in promoters.Integrated multiomics analyses of G.gynandra and the ornamental horticulture C3 relative Tarenaya hassleriana reveal that species-specific whole-genome duplication,gene family expansion,recent LTR–RT amplification,and more recent tandem duplication events have all facilitated the evolution of C_(4) photosynthesis,revealing uniqueness of C_(4) evolution in the Cleome genus.Moreover,high leaf vein density and heat stress resilience are associated with shifted gene expression patterns.The mode of C_(3)-to-C_(4) transition found here yields new insights into evolutionary convergence of a complex plant trait.The availability of this reference-grade genomic resource makes G.gynandra an ideal model system facilitating efforts toward C4-aimed crop engineering.

Altered cerebral cortical microstructure in preterm infants at term-equivalent age relative to term-born neonates

Preterm birth is associated with abnormal brain structure.However,the underlying microstructural properties of cerebral cortical differences in infants born very preterm(VPT,<32 GW)and moderately-late preterm(MLPT,32-37 GW)at term-equivalent age(TEA)relative to full-term(FT)neonates were rarely explored.To achieve this,we use neurite orientation dispersion and density imaging(NODDI)and the method of gray matter-based spatial statistics(GBSS).33 VPT infants,40 MLPT infants)and 69 FT neonates with no evidence of local lesions on conventional MRI adopted from dHCP database were included in this study.By extracting the core voxels of cerebral cortex from the 142 individuals in the standard space,we compared the differences between preterm groups and FT group voxel-wisely.

Fabrication of Neutron-photon Coupling Multi-group Cross-section Library Based on Monte Carlo Method for Discrete Ordinates Transport Code

Radiation shielding calculation plays a critical role in ensuring the safety of nuclear reactors.In the field of nuclear reactor shielding calculations,deterministic computing codes are commonly used due to their computational efficiency and capability to solve deep penetration problems.However,the accuracy of deterministic codes heavily relies on the precision of the multi-group cross section library^([1]).

Nate Williams

Rob Carney发现，作为插画门户网站的主管，有着庞大的客户名录和另一面个性的Nate Williams是商业插画世界不可小觑的一股力量。

Effect of co-existing organic compounds on adsorption of perfluorinated compounds onto carbon nanotubes

Co-existing organic compounds may affect the adsorption of perfluorinated compounds （PFCs） and carbon nanotubes in aquatic environments. Adsorption of perfluorooctane sulfonate （PFOS）, perfluorooctane acid （PFOA）, perfluorobutane sulfonate （PFBS）, and perfluor- ohexane sulfonate （PFHxS） on the pristine multi-walled carbon nanotubes （MWCNTs-Pri）, carboxyl functionalized MWCNTs （MWCTNs-COOH）, and hydroxyl functiona- lized MWCNTs （MWCNTs-OH） in the presence of humic acid, 1-naphthol, phenol, and benzoic acid was studied. Adsorption kinetics of PFOS was described well by the pseudo-second-order model and the sorption equilibrium was almost reached within 24 h. The effect of co-existing organic compounds on PFOS adsorption followed the decreasing order of humic acid 〉 1-naphthol 〉 benzoic acid〉phenol. Adsorbed amounts of PFOS decreased significantly in the presence of co-existing or preloaded humic acid, and both adsorption energy and effective adsorption sites on the three MWCNTs decreased, resulting in the decrease of PFOS adsorption. With increasing pH, PFOS removal by three MWCNTs decreased in the presence of humic acid and phenol. The adsorbed amounts of different PFCs on the MWCNTs increased in the order ofPFBS 〈 PFHxS 〈 PFOA 〈 PFOS. The increase of both initial concentrations and the number of aromatic rings of co-existing organic compounds suppressed PFOS adsorption on the MWCNTs.

INFLUENCE OF THE MIDDLE WEAK LAYER ON THE IMPACT BEHAVIOR OF LAMINATED STRUCTURES

In this paper, a calculation model based on the subsection displacement theory and the large deflection analysis is developed to describe the dynamic response of isotropic laminated circular plates impacted by a soft body. The model takes into account the interlaminar shear effect induced by the middle weak layer. It is proved by numerical examples that the difference between the model developed in this paper and that based on the classical laminated theory mainly depends on three factors, the elastic modulus of the glue, the radius of the circular plate and the impact force.

Transition-Metal-Free Defluorosilylation of Fluoroalkenes with Silylboronates

Silylated fluoroalkenes are important synthetic intermediates with complementary reactivity,which play a key role in the construction of natural products,pharmaceuticals,and manmade materials.Converting the normally highly stable fiuoroalkenes into silylated fluoroalkenes by selective defluorosilylation is a challenging task.Herein,we report a simple,inexpensive and robust defluorosilylation of a variety of fluoroalkenes with silylboronates in the presence of alkoxy base to directly synthesize various silylated fluoroalkenes.The protocol features mild and safe reaction conditions that avoid a catalyst,a transition metal,a ligand,and high reaction temperature and tolerates a wide scope of fluoroalkene substrates without compromising the efficiency.Density functional theory calculations show that transient silyl anion complex undergoes an SN2,or SNv substitution,which is responsible for this base-mediated defluorosilylation.

Comparison of dorsal penile nerve block alone and in combination with lidocaine–prilocaine cream in neonates undergoing circumcision: a randomized controlled study

Background Suboptimal neonatal circumcision analgesia causes a significant stress response.There is continued search for more effective analgesia for neonatal circumcision.We aimed to determine whether lidocaine–prilocaine cream(LPC)prior to dorsal penile nerve block(DPNB)offers better analgesia than DPNB alone.Methods A prospective randomized study of 72 neonates undergoing plastibell circumcision was randomized into two groups of 36 each.Group I received DPNB alone with 4 mg/kg plain lidocaine.Group II had 1 g LPC applied to the phallus 1 hour before DPNB.Serum cortisol levels were measured 30 min preoperatively and 30 min postoperatively.Heart rate(HR)and peripheral arterial oxygen saturation(SpO2)were noted at 30 min preoperatively,after DPNB injection,after excising the prepuce,and at 30 min thereafter.The primary outcome measure was change in serum cortisol levels,while secondary outcomes were changes in HR and SpO2.Results Both groups had increased mean serum cortisol levels,decreased mean SpO2 and increased mean HR from baseline.The rise in mean serum cortisol level was significantly lower in group II(8.09±4.53µg/dL)than that in group I(11.42±7.83µg/dL)(p=0.034).Changes in SpO2 and HR were significantly less in group II than that in group I patients(p<0.05),except for HR changes at 30 min after excision of the prepuce(p=0.086).Conclusion These data suggest that neonates who received LPC prior to DPNB experienced significantly less pain from plastibell circumcision than those who had DPNB alone.

CHARACTERISTICS OF AUTHIGENIC FER-ROMANGANESE CARBONATES IN THE SANYA BAY, HAINAN ISLAND

Authigenic ferromanganese carbonates were first discovered in some shallow and hemipelagic areas by scientists abroad.These minerals have also been found on the offshore along China, especially in the South China Sea (such as the Beibu Bay, the Sanya Bay and the continental shelf). Though the abundance of the carbonates

What can we learn from neonates with COVID-19?

The coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic.Studies on epidemiological and clinical characteristics of patients with COVID-19 have indicated that children are susceptible to SARS-CoV-2 [1-3].To date,the largest study in China reported that over 90% of 2143 children with COVID-19 were asymptomatic,or had mild or moderate illness,and that 5.8% presented critical illness [3].Although the data of neonates are limited and only six neonates with COVID-19 have been reported thus far,several important points should be addressed from these neonatal cases.

Outcomes of complete surgical repair versus palliative intervention in neonates with Tetralogy of Fallot

The ideal surgical approach when managing neonates with Tetralogy of Fallot(TOF)is still controversial.1 In 1945,subclavian artery to pulmonary artery anastomosis was created as palliation for patients with TOF.2 A decade later,Lillehei et al.3 performed the first intracardiac repair for TOF with ventricular septal defect closure and right ventricular outflow obstruction relief.The surgical and perfusion techniques,as well as the postoperative care,have advanced and evolved since that time.Despite that evolution,the two concepts of surgical interventions had remained the same.There is still much debate on what is the ideal surgical approach to infants with TOF,an early primary surgical repair(EPSR)versus a two-staged surgical approach with either an initial temporary shunt for pulmonary blood flow or transcatheter cardiac palliation.The aim of this study was to determine if one strategy had lower mortality than the other and to assess the hospital length of stay and cost of charge in the study groups.

The etiological spectrum of bowel obstruction and early postoperative outcome among neonates at a tertiary hospital in Uganda

Background Bowel obstruction is a common surgical emergency in newborns.One-fourth of neonates with obstruction suffer postoperative complications,with high mortality,especially in low-income countries.Factors attributed to mortality include prematurity,late presentation and associated multiple congenital anomalies.The prevalence and the predictors of mortality in our setting have not been well studied.We aimed to describe the early postoperative outcomes and to determine the predictors of mortality among neonates with bowel obstruction.Methods We conducted a prospective cohort study during 4 months,when we recruited postoperative neonates from the pediatric surgery unit of Mulago Hospital.We collected data on demographics,clinical presentations,maternal characteristics,the surgical procedure performed,postoperative outcomes,etc.After follow-up for 2 weeks,we analyzed the data using Cox proportional hazards regression models of predictors of mortality.Results A total of 76 neonates were recruited,with a male-to-female ratio of 2.2:1.The age ranged from 1 to 26 days,a median of 3[interquartile range(IQR):2,7].About 67.1%had birth weights ranging between 2.5 kg and 3.5 kg,a mean of 2.8[standard deviation(SD)=0.64];76.3%were termed;with anorectal malformation(ARM),31.6%as the leading cause,followed by jejunoileal atresia(JIA),25%.Nearly 55.3%of neonates developed complications;53.9%with post-operative fever,15.8%had wound sepsis.The mortality rate was 44.7%(34/76)and was highest among cases of JIA,41.2%.The predictors of mortality included prematurity,fever at admission,breastfeeding status,and mother’s parity as well as the cadre of healthcare providers(p<0.005).Conclusions ARM is the predominant cause of bowel obstruction among neonates,followed by JIA.The morbidity and mortality due to bowel obstruction among neonates are unacceptably high.The major predictors of mortality were prematurity,fever at admission,and the cadre of the healthcare providers.

Natee Utarit 延续画作的灵魂

科技教会了我们如何以客观、精确来观察万物。在手中没有手机,耳边没有听筒的年代,那种通过想像力来认知世界的方式,被视为一种漠视文明的错误态度。在急速的进步中,促使我们以理智为尺度去理解一切,因此全面捕捉此情此景的摄影技术,取代了画笔成为记载历史和生活的工具。在客观态度的影响下,艺术的价值不仅在于作品所蕴藏的涵义,而是在于它在拍卖会上在哪个价位被判处流放。冷冰冰的外在因素,逐渐侵蚀着艺术作为灵性载体的本质。

基于前馈补偿LQR与PID的矿井无轨胶轮车横纵向控制研究

无人驾驶技术是实现无轨胶轮车井下安全、智能、高效运输的重要方案之一,为了提高无人驾驶过程中的轨迹跟踪精度,提出了基于前馈补偿的横向线性二次型调节器(Linear Quadratic Regulator,LQR)与纵向比例积分微分(Proportion Integration Derivative,PID)位移速度调节器相结合的控制策略,实现车辆的横纵向协调控制。通过建立考虑轮胎侧偏特性的2自由度无轨胶轮车动力学模型和跟踪误差模型,并采用井下无轨胶轮车实车参数建立其电机模型,得到车辆的驱动制动输出。利用Carsim和Matlab/Simulink搭建联合仿真环境,分别在井下双车道工况、单车道工况与颠簸路面工况下进行了轨迹跟踪仿真验证。结果表明:在3种工况下车辆轨迹跟踪过程中的最大横向误差仅为5 cm,最大纵向误差仅为10 cm,速度误差控制在1 m/s以内,航向误差范围为±0.1 rad,前轮偏转角变化平稳未出现抖动现象。为验证控制器在井下实际环境下的跟踪性能,使用实验室小车于陕西某井下巷道进行了现场试验验证,结果表明:井下实际巷道下试验结果误差仍在合理范围内,解决了车辆运行过程中的速度和路径的时变问题,反映出该控制器具有较高的精度和较好的稳定性。

Restorative Justice in China

The purpose of restorative justice resonates with some embedded idea of traditional Chinese culture which regards the ultimate goal of judicial activities as avoidance of lawsuits.

工程塑料环境因素与载荷应力耦合作用试验装置研究

目的 设计一种能够模拟工程塑料实际服役工作环境的试验装置,在多型自然环境中,构建兼具环境因素侵蚀与载荷应力耦合作用的试验条件。方法 研制工程塑料环境因素与载荷应力协同作用试验装置,采用包括拉伸加载、弯曲加载、控制系统等组件的模块化设计,实现0.01~16 Hz加载频率的拉伸及弯曲载荷,最大1 550 kg的拉伸载荷,最大375 kg的弯曲载荷。结果 将研制完成的试验装置置于多型自然环境下对试验施加恒定和交变载荷,以真实模拟工程塑料实际服役中的环境因素与载荷应力协同作用。结论 试验装置制造加工难度小,结构稳定可靠,可用于评价和研究工程塑料等系列类型材料的环境损伤性能演变。

溶剂萃取技术在磷矿加工工艺中的应用

溶剂萃取技术作为工业物质分离提纯中最常用的方法之一,被广泛应用于磷矿加工的多个环节。简述了溶剂萃取技术在磷矿制备磷酸的工艺过程的应用,重点介绍了磷矿加工过程中湿法磷酸和萃余酸的萃取、净化以及磷矿伴生氟、碘及稀土资源的萃取回收工艺,并将萃取法和其它净化方法进行了对比,最后对溶剂萃取技术在磷矿加工过程中的应用做出了总结并给出了未来的研究建议。

石油石化污染场地生物修复技术工程应用案例分析

通过多角度分析国内外石油石化场地生物修复公开工程案例,结果表明:案例数量美国第一,中国第二,其次是加拿大、德国、墨西哥等国家;相比于生物堆等异位微生物技术,生物通风等原位技术成本低,应用更为广泛,但修复周期较长;工程案例数量和修复成本从高到低的排序均是:石油泄漏工业场地、农田污染场地、军事基地污染场地等;生物修复的特征污染物依次包括石油烃、含氯乙烯、重金属、多环芳烃等,其中杂酚油的修复成本最高。

基于矩阵优化分解的测绘图像三维重建系统

由于测绘图像细节信息特征独立性显著,三维重建波段的选取易出现偏差,影响测绘图像三维重建效果。为此,本文设计基于矩阵优化分解的测绘图像三维重建系统。设计测绘图像导入主从设备接口,实现测绘图像数据导入处理。3D引擎图像渲染模块和多通道三维显示模块可以实现多台计算机对同一场景的渲染。采用矩阵优化分解方法选择图像三维重建波段,将波段上任意点到对应极线距离作为重建目标,连接所有坐标形成曲面,计算各点三维笛卡尔坐标值,并恢复测绘图像被遮挡部分,修正波段值,实现三维重建。测试结果表明:该系统重建的三维图像像素均匀,无异常凸起部分。重建误差平均为0.06,具有精准三维重建效果。