Effects of Ni catalyzer on growth velocity and morphology of SiC nano-fibers

Composite felts reinforced by both SiC nano-fibers(SiC-NFs)and carbon fibers were prepared at 1 273 K using Ni granules as catalyzers with different deposition time.SiC-NFs were deposited on the surface of the carbon fibers in situ by catalytic chemical vapor deposition(CCVD).The phase,microstructure and morphology of the fibers after electroplating and deposition were characterized by XRD,SEM and TEM.The results show that the SiC-NFs produced by CCVD are composed of single crystal of β-SiC.It is found that smaller nano-granules are more active as catalyzers.The resulting SiC-NFs appear more spindle-like and have a more homogeneous dispersion.The mass change of the samples before and after deposition shows that using more Ni granules results in a faster growth velocity of SiC-NFs.With the same electroplating time,the growth velocity of the SiC-NFs first increases and then decreases.At around 4 h,it reaches the maximum growth velocity,and it becomes nearly constant at around 8 h.After 8 h, the stable growth velocity of the electroplated Ni samples is faster than that of the conventional sample produced without catalyzers, because the SiC-NFs can improve the specific surface area and the activity of the surface.

Effects of flow velocity on electrochemical behavior of seachest 5083-H116 Al alloy for ship

Electrochemical behavior of 5083-H116 Al alloy with flow velocity of seachest material for Al ship was evaluated.To examine the electrochemical characteristics of flow velocity and its effects on the performance of the alloy,experiments were conducted at four flow velocity variables using static state with an agitator.An ultrasonic vibration generator using piezoelectric effect was used in cavitation test according to the requirements of in ASTM-G32.The results show that the corrosion current density and damage were increased by applying the flow velocity compared to static state.Therefore,it is determined that the case of applying flow velocity is weaker to the corrosion.

Comparative Analyses of Height Growth Velocities of School Boys in South Korea and Japan in the Past 50 Years

The paper compares the height growth velocities of male schoolchildren in South Korea and Japan over the period 1961-2018. Growth in height was measured with the same birth cohorts, not by comparing mean height of ascending ages in the same year. Starting from a lower economic base and mean height in the 1960s, high school males aged 17 in South Korea became 3 cm taller in mean height than their Japanese peers in the mid-2000s versus 2 - 3 cm shorter in the 1960s through 1970s. Children in Japan ceased to grow taller by the end of the 1980s, not because they quit taking more animal-sourced foods, meat and milk, but because they had drastically steered away from fruit and vegetables in their diets since the end of the 1970s. Having largely converged economically with Japan, South Korean children ceased to grow any taller in the mid-2000s. More importantly, it was discovered in this study that successive cohorts in South Korea started to fall gradually but steadily in height growth velocity from 1st graders in middle school, aged 12 years to 3rd graders in high school, and aged 17 years, to be once again 3 cm below their Japanese peers in the early-2010s. Analysis of Korea Household Expenditure Surveys classified by age groups of household head, decomposed by the author, revealed that children under 20 years of age in South Korea began to steer away from fruit and, particularly, vegetables in their at-home consumption in the mid-1990s, to average only 15% of the level of older adults in their 50s in the mid-2010s. These results lend supports to the importance of fruit and vegetables as determinants in height and its growth velocities in two genetically similar nations over time and stages of economic growth.

子痫风险预测联合脐动脉S/D比值对妊娠期糖尿病患者妊娠结局的预测价值

目的探讨子痫风险预测联合脐动脉收缩期峰值流速与舒张末期流速(peak systolic velocity/end diastolic velocity,S/D)比值对妊娠期糖尿病患者妊娠结局的预测价值。方法选取2021年1月至2023年1月笔者医院产科门诊收治的60例妊娠期糖尿病(gestational diabetes mellitus,GDM)患者作为妊娠糖尿病组;同一时间,选取笔者医院产科门诊孕检正常的健康孕妇30例作为对照组。采用磁微粒化学发光法检测血清胎盘生长因子(placental growth factor,PIGF),超声检测,S/D比值同时按照是否合并不良妊娠结局分为妊娠结局良好组及不良妊娠结局组,比较PIGF及S/D比值;采用受试者操作特征(receiver operating characteristic,ROC)曲线分析PIGF联合S/D比值对GDM患者妊娠结局的预测价值进行预测分析。结果与对照组比较,妊娠糖尿病组患者PIGF降低,S/D升高(P<0.05)。对照组不良妊娠结局的发生率为20.00%,妊娠糖尿病组不良妊娠结局的发生率为46.67%,与对照组比较,妊娠糖尿病组不良妊娠结局的发生率升高(P<0.05)。与妊娠结局良好组比较,不良妊娠结局组的GDM患者PIGF水平降低,S/D比值升高(P<0.05)。ROC曲线分析PIGF、S/D比值对GDM患者不良妊娠结局敏感度及特异性分析发现,S/D比值诊断效果高于PIGF,但联合更高。结论妊娠期糖尿病患者中PIGF水平降低,S/D比值增加,且与患者不良妊娠结局相关,PIGF联合S/D比值对患者不良妊娠结局的诊断效能最高。

Phase-field simulations of forced flow effect on dendritic growth perpendicular to flow

The effect of supercooled melt forced laminar flow at low Reynolds Number on dendritic growth perpendicular to melt flow direction was investigated with the phase-field method by incorporating melt convection and thermal noise under non-isothermal condition. By taking the dendritic growth of high pure succinonitrile （SCN） supercooled melt as an example, side-branching shape difference of melts with flow and without flow was analyzed. Relationships among supercooled melt inflow velocity, deflexion angle of dendritic arm and dendritic tip growth velocity were studied. Results show that the melt inflow velocity has few effects on the dendritic tip growth velocity. A formula of relationship between the velocity of the melt in front of primary dendritic tip and the dendritic growth time was deduced, and the calculated result was in quantitative agreement with the simulation result.

Phase-field simulation of forced flow effect on random preferred growth direction of multiple grains

The random distribution problem of dendrite preferred growth direction was settled by random grid method.This method was used to study the influence of forced laminar flow effect on multiple grains during solidification.Taking high pure succinonitrile （SCN） undercooled melt as an example,the forced laminar flow effect on multiple grains was studied by phase-field model of single grain which coupled with flow equations at non-isothermal condition.The simulation results show that the random grid method can reasonably settle the problem of random distribution and is more effective.When the solid fraction is relatively low,melt particles flow around the downstream side of dendrite,and the flow velocity between two dendrite arms becomes high.At the stage of solidification time less than 1800Δt,every dendrite grows freely;the upstream dendrites are stronger than the downstream ones.The higher the melt flow rate,the higher the solid fraction.However,when the solid fraction is relatively high,the dendrite arm intertwins and only a little residual melt which is not encapsulated can flow;the solid fraction will gradually tend to equal to solid fraction of melt without flow.

IGF-1及其相关指标对CPP患儿GnRHa治疗期间生长减速的诊断价值

目的 分析胰岛素样生长因子-1(IGF-1)及其相关指标对中枢性性早熟(CPP)患儿促性腺激素释放激素类似物(GnRHa)治疗期间生长减速的诊断价值,并找出最佳参考指标及截断值以指导临床工作。方法 回顾分析53例接受GnRHa治疗的特发性CPP女童的临床资料[身高、骨龄(BA)、生长速率(CV)等],分析IGF-1及其相关指标、性激素等与生长速度的相关性,并采用受试者工作特征(ROC)曲线分析CPP患儿过度生长减速的最佳参考指标。结果 GV、GV SDS与ΔBA-IGF-1 SDS、治疗12个月时的雌二醇(E2)均呈正相关,与初诊时BA-IGF-1 SDS均呈负相关(P<0.05)。患儿以GV SDS≥0和GV SDS<0分组,ΔBA-IGF-1 SDS的ROC曲线面积最大[曲线下面积(AUC)=0.782],其最佳界值点为-1.274。结论 在GnRHa治疗期间生长减速与生长激素(GH)-IGF-1轴的变化、性类固醇缺乏有关,ΔBA-IGF-1 SDS可考虑作为CPP患儿GnRHa治疗后临床上指导联合使用重组人生长激素(rhGH)的参考指标。

超声收缩期峰值血流速度、阻力指数与乳腺癌组织中Survivin、基质金属蛋白酶-11、人类表皮生长因子受体2关系研究

目的:探讨超声收缩期峰值血流速度(PSV)、阻力指数(RI)与乳腺癌组织中Survivin、基质金属蛋白酶-11(MMP-11)、人类表皮生长因子受体2(HER2)的关系。方法:选取60例乳腺癌患者作为观察组,另选择同期60例乳腺良性病变患者作为对照组。均行手术治疗,术前经超声检测,比较两组患者术前RI值、PSV值,免疫组化法检测术后癌组织中Survivin、MMP-11、HER2的表达,分析Survivin、MMP-11、HER2表达与超声RI、PSV值的关系。结果:观察组RI、PSV值高于对照组(均P<0.05)。观察组癌组织中Survivin、MMP-11、HER2表达阳性率高于对照组(均P<0.05)。不同病灶直径、临床分期患者RI、PSV值,不同病灶直径、临床分期及是否淋巴结转移患者癌组织中Survivin、MMP-11、HER2表达比较,差异有统计学意义(均P<0.05)。癌组织中Survivin、MMP-11、HER2表达与PSV、RI值呈正相关(均P<0.05)。结论:超声检测RI、PSV值对术前判断乳腺癌有一定价值,RI、PSV值与乳腺癌癌组织Survivin、MMP-11、HER2表达均相关,Survivin、MMP-11、HER2在乳腺癌的发生、发展过程中发挥重要作用。

Efficacy and safety of nerve growth factor for the treatment of neurological diseases:a meta-analysis of 64 randomized controlled trials involving 6,297 patients

OBJECTIVE： China is the only country where nerve growth factor is approved for large-scale use as a clinical medicine. More than 10 years ago, in 2003, nerve growth factor injection was listed as a national drug. The goal of this article is to evaluate comprehensively the efficacy and safety of nerve growth factor for the treatment of neurological diseases. DATA RETRIEVAL： A computer-based retrieval was performed from six databases, including the Cochrane Library, PubMed, EMBASE, Sino Med, CNKI, and the VIP database, searching from the clinical establishment of nerve growth factor for treatment until December 31, 2013. The key words for the searches were ＂nerve growth factor, randomized controlled trials＂ in Chinese and in English. DATA SELECTION： Inclusion criteria： any study published in English or Chinese referring to randomized controlled trials of nerve growth factor; patients with neurological diseases such as peripheral nerve injury, central nerve injury, cranial neuropathy, and nervous system infections; patients older than 7 years; similar research methods and outcomes assessing symptoms; and measurement of nerve conduction velocities. The meta-analysis was conducted using Review Manager 5.2.3 software. MAIN OUTCOME MEASURES： The total effective rate, the incidence of adverse effects, and the nerve conduction velocity were recorded for each study. RESULTS： Sixty-four studies involving 6,297 patients with neurological diseases were included. The total effective rate in the group treated with nerve growth factor was significantly higher than that in the control group （P 〈 0.0001, RR： 1.35, 95%CI： 1.30-1.40）. The average nerve conduction velocity in the nerve growth factor group was significantly higher than that in the control group （P 〈 0.00001, MD. 4.59 m/s, 95%CI： 4.12-5.06）. The incidence of pain or sclero- ma at the injection site in the nerve growth factor group was also higher than that in the control group （P 〈 0.00001, RR： 6.30, 95%CI： 3.53-11.27）, but such adverse effects were mild. CONCLUSION： Nerve growth factor can significantly improve nerve function in patients with nervous system disease and is safe and effective.

Growth-Promoting Effect of Recombinant Human Growth Hormone and Stanozolol in Girls with Turner Syndrome

Summary: Ten girls with Turner syndrome were treated with a combination therapy of recombinant human growth hormone (R hGH) and low dose stanozolol for a period of 8 to 36 months. The results showed that when compared with the growth rate before the treatment, the growth rates after treatment with R hGH and stanozolol showed a sustained increase, reaching 9.0±1.9 cm/year during the first year of treatment; the height age increase by 2.5±0.8 years while the bone age increase were 1.0±0.7 years; and the predicted final adult height at the end of the first year of the treatment increased to 149.4±6.1 cm compared to their original mean of 142.8±4.2 cm. We are led to conclude that therapy with R hGH in combination with stanozolol can increase the growth velocity and significantly increase the predicted adult height of children with Turner syndrome.

Microstructure transition from stable to metastable eutectic growth in Ni-25%Al alloy

The microstructural evolution during directional solidification of the Ni-25%Al(mole fraction) alloy was investigated in the range of growth velocity from 10 to 100 μm/s under a given thermal gradient of 10 K/mm. The solidification microstructures reveal a transition from γ'-β equilibrium eutectic to γ-β metastable eutectic plus β dendrites. A mixed microstructure of γ'-β and γ-β eutectics produced at a growth velocity of 25 μm/s illustrates that the transition occurs during the competitive growth between γ and γ' phases. The growth temperature for each phase was considered to understand the microstructure selection during solidification. The experimental results show that a phase or a microstructure solidifying with the highest temperature under a given growth condition is preferentially selected upon solidification. In addition, both stable eutectic and metastable eutectic are shown to coexist and simultaneously grow in the velocity range between 25 and 60 μm/s due to their similar growth temperatures.

电针介入时机对大鼠面神经损伤再生修复的影响

目的探讨电针治疗周围性面瘫大鼠最佳介入时机及其功能机制。方法选用SD大鼠50只,随机分为5组(假手术组、模型组、急性期组、静止期组、恢复期组),每组10只,采用神经卡压法建立左侧周围性面瘫模型。急性期组、静止期组、恢复期组分别于术后1 d、1周、2周开始给予电针治疗,术后4周,比较各组治疗前后行为学评分和面运动神经传导速度,采用Western blot法检测神经生长因子(nerve growth factor,NGF)、血管内皮生长因子(vascular endothelial growth factor,VEGF)蛋白表达。结果急性期组、静止期组、恢复期组术后4周行为学评分均低于模型组(P<0.05),面运动神经传导速度均高于模型组(P<0.05);急性期组、静止期组、恢复期组术后4周行为学评分均低于术后(P<0.05),面运动神经传导速度均高于术后(P<0.05);术后4周行为学评分静止期组低于恢复期组(P<0.05),急性期组低于静止期组和恢复期组(P<0.05),面运动神经传导速度静止期组高于恢复期组(P<0.05),急性期组高于静止期组和恢复期组(P<0.05)。术后4周急性期组、静止期组、恢复期组面神经组织的NGF、VEGF表达高于模型组(P<0.05),静止期组高于恢复期组(P<0.05),急性期组高于静止期组(P<0.05)。结论电针介入时间越早对损伤面神经的再生修复效果越佳,其部分机制可能与电针上调NGF、VEGF的表达有关。

Numerical simulation for isothermal dendritic growth of succinonitrile-acetone alloy

Numerical simulation based on phase field method was developed to describe the solidification of two-dimensional isothermal binary alloys. The evolution of the interface morphology was shown and the effects of phase field parameters were formulated for succinonitrile-acetone alloy. The results indicate that an anti-trapping current(ATC) can suppress many trapped molten packets, which is caused by the thickened interface. With increasing the anisotropy value from 0 to 0.05, a small circular seed grows to develope secondary dendritic, dendritic tip velocity increases monotonically, and the solute accumulation of solid/liquid interface is diminished distinctly. Furthermore, with the increase of the coupling parameter value, the interface becomes unstable and the side branches of crystals appear and grow gradually.

70例胎儿生长受限脐动脉血流参数及围产期情况的研究分析

目的分析胎儿生长受限(FGR)脐动脉血流参数及围产期情况。方法选取2019年1月至2021年9月我院收治的70例胎儿生长受限(FGR)孕妇为观察组,70例胎儿无生长异常孕妇作为对照组。对比两组的胎儿脐动脉血流参数及围产期情况。结果与对照组相比,观察组胎儿脐动脉收缩期最大血流速度(PSV)、舒张末期血流速度(EDV)、时间平均峰值流速(TAmax)较低,S/D、搏动指数(PI)、阻力指数(RI)较高(P<0.05)。观察组发生早产、脐带扭转及脐血流指标异常发生率及剖宫产率高于对照组(P<0.05)。结论超声检测孕妇脐动脉血流频谱的速度参数及S/D、RI、PI对FGR诊断有重要参考价值;FGR孕妇早产、脐带扭转及脐血流指标异常发生率及剖宫产率高于正常孕妇。

不同流速对许氏平鲉生长及行为的影响

文章以许氏平鲉(Sebastes schlegelii)幼鱼为研究对象,研究了不同流速对许氏平鲉幼鱼生长性能和行为表现的影响。实验共设置4个流速处理组,分别为0(C组)、0.5 BL/s(L组)、1.5 BL/s(M组)和2.5 BL/s(H组),实验周期为43d。研究共监测与分析了8个行为指标,并将其归为运动参数(平均速度和最大加速度)、偏好区域(内、中和外圈累计停留时间)和活动状态(最大轮替次数、活跃性和身体接触)等3类行为状态。结果表明:(1)在整个实验周期中,M组和L组的终体长显著高于C组和H组(P<0.05);M组的终体重、特定生长率和增重率显著高于C组和H组(P<0.05)。(2)在实验30d后,M组和H组的外圈累计停留时间显著低于C组和L组(P<0.05),且M组中圈累计停留时间显著高于C组和H组(P<0.05);H组的中圈累计停留时间显著低于其他处理组(P<0.05),其内圈累计停留时间显著高于其他处理组(P<0.05),且各处理组间没有显著差异(P>0.05);M组的最大加速度显著高于C组和L组(P<0.05),且36d后,M组的平均速度显著高于其他所有处理(P<0.05)。综上所述,M组(1.5 BL/s)流速能够促进许氏平鲉的生长,此外,流速的变化显著影响着许氏平鲉在不同圈层圈的累计停留时间、区域间轮替次数、活跃性和身体接触等行为特征,可以将区域偏好及活动状态等指标作为评价许氏平鲉应对不同流速条件的行为响应指标。

黄芪桂枝五物汤对肘管综合征患者肘管扩大成形术后尺神经运动传导速度和上肢功能的影响

目的:研究黄芪桂枝五物汤对肘管综合征患者肘管扩大成形术后尺神经运动传导速度、上肢功能以及血清白介素-1(IL-1)、肿瘤坏死因子-α(TNF-α)和神经生长因子(NGF)的影响。方法:选择行肘管扩大成形术治疗的肘管综合征患者80例为研究对象,随机分为对照组和观察组,每组40例,对照组采用甲钴胺片治疗,观察组给予黄芪桂枝五物汤加甲钴胺片治疗。治疗3个月后,比较两组疗效、尺神经运动传导速度、上肢功能优良率以及血清白介素-1(IL-1)、肿瘤坏死因子-α(TNF-α)、神经生长因子(NGF)、谷丙转氨酶(ALT)、尿素氮(BUN)及肌酐(Cr)水平。结果:观察组总有效率及上肢功能恢复优良率高于对照组,尺神经运动传导速度快于对照组,血清IL-1、TNF-α、NGF水平明显低于对照组(均P<0.05)。治疗前后两组ALT、BUN及Cr水平比较差异无统计学意义(均P>0.05)。结论:黄芪桂枝五物汤能够提升肘管综合征患者术后尺神经运动传导速度,改善上肢功能,降低血清IL-1、TNF-α、NGF水平。

热伴流中甲烷射流的自燃特性研究

采用高速化学自发光测量方法对热伴流中甲烷射流的自燃特性进行了实验研究,研究了不同射流速度、伴流温度和当量比下,自燃火核的生长速率、长宽比、质心运动速度随时间的演变规律.结果表明:随着射流速度的增加,自点火位置显著下降;进一步升高射流速度并没有明显改变火核出现的位置,但是会阻碍火核的生长;在射流速度、伴流当量比一定的情况下,火核生长速率和长宽比在高、低伴流温度间表现出不同的行为.低伴流温度下,火核生长更快且接近统一的长宽比,而高伴流温度下,长宽比随射流速度的增加而增加,这表明火核不再是圆形而是在轴向拉长.

Effects of Strontium,Magnesium Addition,Temperature Gradient,and Growth Velocity on Al-Si Eutectic Growth in a Unidirectionally-solidified Al-13 wt%,Si Alloy

Al-Si eutectic growth mechanism was investigated in a directionally-solidified AI-1 3 wt% Si alloy with different strontium （Sr） and magnesium （Mg） additions, growth velocities and temperature gradients. Macro- and micro- scale metallographic analyses revealed that addition level of Sr and Mg, temperature gradient and growth velocity are important factors affecting stability of solidifying AI-Si eutectic front and the final morphology of eutectic grains in the solidified A1-13 wt% Si alloys. By varying （tailoring） these factors, a variety of eutectic grain structures and morphologies such as planar front, cellular structure, a mix of cellular and columnar, or equiaxed dendrites, can be obtained. Increasing temperature gradient, reducing growth velocity, or decreasing Sr and Mg contents is beneficial to stabilizing planar growth front of eutectic grains, which is qualitatively in accordance with constitutional supercooling criterion for binary eutectic growth. In contrast, adding more Sr and Mg, increasing growth velocity, or decreasing temperature gradient produces large constitutional supercooling, leading to columnar-equiaxed transition （CET） of eutectic structure, which can be interpreted on the basis of Hunt＇s Model. It is also found that both solute concentration and solidification variables have significant impact not only on eutectic growth, but also on gas porosity formation.

喂养方式对婴幼儿生长速率影响的研究进展

生长速率是评价儿童某一生长阶段的体格生长状况最直观、具体、精确的研究指标之一。早期喂养方式对婴幼儿体格生长的影响受到众多领域研究学者的广泛关注。本文通过整理近年发表的关于喂养方式对婴幼儿生长速率影响的文献,了解国内外喂养方式对婴幼儿生长速率影响的研究现状、可能的机制和原因,以及存在的问题,以期为今后开展相关研究提供借鉴和参考。

Magnetic resonance imaging of knees:a novel approach to predict recombinant human growth hormone therapy response in short-stature children in late puberty

Background There is no appropriate tool to predict recombinant human growth hormone(rhGH)response before therapy initiation in short-stature children in late puberty.The current study aimed to explore the associations between magnetic resonance imaging(MRI)stages of the knee growth plates and rhGH response in short-stature children in late puberty.Methods In this prospective cohort study,short-stature children in late puberty were treated with rhGH and followed up for 6 months.We proposed a novel knee MRI staging system according to the growth plate states of distal femurs or proximal tibias and divided the participants into three groups:unclosed growth plate group,marginally closed growth plate group,and nearly closed growth plate group.The primary outcomes were height gain and growth velocity(GV),which were assessed three months later.Results Fifty participants were enrolled,including 23 boys and 27 girls.GV and height gain after 6 months of rhGH therapy decreased successively in the three groups with an increased degree of growth plate fusion,especially when grouped by proximal tibias(GV_(1-3 mon)from 9.38 to 6.08 to 4.56 cm/year,GV_(4-6 mon)from 6.75 to 4.92 to 3.25 cm/year,and height gain from 4.03 to 2.75 to 1.95 cm,all P<0.001).Moreover,the MRI stages of growth plates independently served as a significant variable for GV and height gain after therapy,especially when grouped by proximal tibias(all P<0.01).Conclusion The MRI staging method is expected to be an effective tool for predicting rhGH response before therapy initiation in short-stature children in late puberty.