固溶温度对电弧增材马氏体时效钢组织和性能的影响

研究了固溶温度对电弧增材制造马氏体时效钢显微组织和力学性能的影响。结果表明:经过固溶和时效处理后,电弧增材制造马氏体时效钢枝晶间偏析区域形成了逆变奥氏体。随着固溶温度升高,时效处理后产生的逆变奥氏体面积分数减少,尺寸减小,这是由于固溶温度升高加快了枝晶间合金元素的扩散,从而降低了枝晶间奥氏体稳定化元素的偏析程度。与堆积态相比,经过固溶和时效处理后电弧增材制造马氏体时效钢强度大幅增加的同时断后伸长率几乎不变。这是由于单个逆变奥氏体晶粒内从心部到边缘机械稳定性梯度分布、不同逆变奥氏体晶粒之间机械稳定性存在差异,在拉伸应变增加过程中,不同机械稳定性的逆变奥氏体晶粒从边缘到心部依次发生形变诱导马氏体相变,产生“广谱的”相变诱导塑性效应,协调塑性变形。固溶温度增加,时效处理后的电弧增材制造马氏体时效钢强度和断后伸长率略微降低,这是由于固溶温度增加导致逆变奥氏体面积分数和机械稳定性降低,延长加工硬化阶段的能力下降,造成强度降低;同时逆变奥氏体面积分数降低在拉伸载荷下产生的相变诱导塑性效应减弱,导致断后伸长率略微降低。

抗炎饮食联合粪便移植对溃疡性结肠炎患者肠道菌群多样性及耐受性的影响

目的探讨抗炎饮食联合粪便移植对溃疡性结肠炎(ulcerative colitis,UC)患者肠道菌群多样性及耐受性的影响。方法纳入2022年3月至2023年4月新疆医科大学第一附属医院150例UC患者,采用随机数字表法将患者分为饮食组、移植组和联合组,每组50例。饮食组予以抗炎饮食干预,移植组予以粪便移植治疗,联合组予以抗炎饮食联合粪便移植干预。8周后,比较三组UC缓解情况及肠道菌群多样性,并比较移植组与联合组粪便移植耐受性。结果联合组临床缓解为40.0%、内镜缓解率为32.0%,均显著高于饮食组、移植组(P<0.05),但黏膜愈合率三组间比较差异无统计学意义(P>0.05)。治疗后,联合组ace、chao、shannon指数均高于饮食组、移植组(P<0.05),且移植组均高于饮食组(P<0.05)。联合组粪便移植不良耐受性反应发热、食欲不振发生率低于移植组,腹痛联合组高移植组,但差异均无统计学意义(P>0.05)。结论抗炎饮食与粪便移植联合应用可有效提高UC患者肠道菌群多样性,促进患者临床及内镜缓解,且不增加粪便移植不耐受性反应。

New HⅠObservations Toward the NGC 5055 Galaxy Group with FAST

We report a new high-sensitivity HⅠmapping observation of the NGC 5055 galaxy group over an area of 1°.5×0°.75 with the Five-hundred-meter Aperture Spherical radio Telescope(FAST).Our observation reveals that the warped HⅠdisk of NGC 5055 is more extended than what was previously observed by WSRT,out to239(61.7 kpc).The total HⅠmass of NGC 5055 is determined to be~1.1×10^(10)M_Θ.We identified three HⅠclouds with HⅠmasses of the order of~10^(7)M_Θat the southeastern edge of the HⅠdisk,as well as a candidate high-velocity cloud with an HⅠmass of(1.2±0.5)×10^(6)M_Θto the north of NGC 5055.The HⅠcontent of UGCA337 is robustly detected for the first time by the FAST observations.It has a narrow HⅠlinewidth of W_(50)=17.4±3.8 km s^(-1)with a total HⅠmass of(3.5±0.3)×10^(6)M_Θ.Comparing the gas content and g-r color of UGCA 337 with typical low-mass dwarf galaxies,UGCA 337 appears relatively gas-poor despite its blue color.This suggests that UGCA 337 may have undergone gas stripping in the past.We also analyzed the possible origin of the diffuse HⅠclouds located at the outskirts of NGC 5055,and speculate that they might be the remnant features of a merger event in the past.

Toward a Direct Measurement of the Cosmic Acceleration:The Pilot Observation of HI 21 cm Absorption Line at FAST

This study presents results on detecting neutral atomic hydrogen(H I)21 cm absorption in the spectrum of PKS PKS1413+13 at redshift z=0.24670041.The observation was conducted by FAST,with a spectral resolution of10 Hz,using 10 minutes of observing time.The global spectral profile is examined by modeling the absorption line using a single Gaussian function with a resolution of 10 kHz within a 2 MHz bandwidth.The goal is to determine the rate of the latest cosmic acceleration by directly measuring the redshift evolution of the H I 21 cm absorption line with Hubble flow toward a common background quasar over a decade or longer time span.This will serve as a detectable signal generated by the accelerated expansion of the Universe at redshift z<1,referred to as redshift drift z(5)or the SL effect.The measured H I gas column density in this DLA system is approximately equivalent to the initial observation value,considering uncertainties of the spin temperature of a spiral host galaxy.The high signal-to-noise ratio of 57,obtained at a 10 kHz resolution,strongly supports the feasibility of using the H I 21 cm absorption line in DLA systems to accurately measure the redshift drift rate at a precision level of around 10~(-10)per decade.

盾构隧道废弃泥浆絮凝沉淀试验及处理效果评价

为明确盾构隧道废弃泥浆的固液分离性能,提高分离效率,试验选取非离子型聚丙烯酰胺、阴离子型聚丙烯酰胺以及聚合氯化铝作为研究对象,研究三者在不同分子量、浓度及添加量下的絮凝沉淀效果。基于单一絮凝剂的试验结果,进一步选取复合絮凝剂进行试验研究。结果表明,絮凝效果由强到弱的排序为阴离子型聚丙烯酰胺>非离子型聚丙烯酰胺>聚合氯化铝,其中阴离子型聚丙烯酰胺的絮凝沉淀效果远远好于非离子型聚丙烯酰胺及聚合氯化铝,有机絮凝剂聚合氯化铝的泥水分离速度比其他两种絮凝剂慢,但上清液浊度远远低于无机高分子絮凝剂。对比分析发现,复合絮凝剂阴离子型聚丙烯酰胺添加量为70 mL,聚合氯化铝添加量为10 mL时,底泥体积相对较小,同时上清液浊度大大降低,达到绿色高效的处理要求。

一例中华小熊猫杀婴行为分析

杀婴是一种特殊的行为,在动物界中广泛存在。为了探明圈养中华小熊猫(Ailurus styani)杀婴的原因,研究人员对1只中华小熊猫母兽的杀婴行为进行观察研究。结果表明:环境因素、人为干扰等均能诱发小熊猫杀婴行为,噪音可能是影响核桃坪基地小熊猫母兽杀婴的主要诱因。本研究目的在于为制定科学合理的中华小熊猫饲养管理措施,减少或避免杀婴行为的发生,并为提高幼仔存活率提供参考。

电弧增材制造TA15钛合金的组织与性能研究

采用CMT电弧增材制造技术制备TA15钛合金堆积体,并对其显微组织和拉伸性能进行研究。结果表明:CMT电弧增材制造TA15钛合金堆积体成形良好,沿高度方向的宏观组织为外延生长的粗大β柱状晶,显微组织主要由网篮组织、片层组织组成。CMT电弧增材制造TA15钛合金堆积体在水平打印方向与增材高度方向的抗拉强度和屈服强度相差小,但增材高度方向的断后伸长率则优于水平打印方向。

基于量子点的检测技术在法庭科学物证鉴定中的应用研究进展

由于具有独特的纳米尺寸效应和高灵敏度的光电效应,碳量子点以及半导体量子点技术已经被广泛应用于材料科学、生物和医药等领域。本文在简述量子点结构、合成方法等基础上,着重介绍了基于量子点的检测技术在法庭科学领域毒物、毒品和微量物证鉴定中的应用,旨在分析基于量子点的检测技术研究与应用现状,展望其在法庭科学领域中的应用前景。

Region coverage control for multiple stratospheric airships with combined self-/event-triggered mechanism

The region coverage control problem of multiple stratospheric airships system is firstly addressed in this paper.Towards it,we propose a two-layer control framework with the artificial potential field(APF)-based region coverage control law and the adaptive tracking control law.The APF-based region coverage control law ensures the coverage task is achieved until every single stratospheric airship ends up performing station keeping where near the respective global minimum point,in which an innovative solution to the local minimum problem is put forward.The adaptive tracking control law is designed to realize motion control using tracking the desired velocity and angular velocity given by coverage control law,with the consideration of several practical control problems as unknown individual differences and external disturbances.To save resources,the combined self-/event-triggered mechanism designed therein significantly reduces the times of state information transmission and control law calculation.The effectiveness of the proposed control framework is verified through simulations.

Performance of FAST with an Ultra-Wide Bandwidth Receiver at 500–3300 MHz

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)has been running for several years.A new ultra-wide bandwidth(UWB)receiver,simultaneously covering 500-3300 MHz,has been mounted in the FAST feed cabin and has passed a series of observational tests.The whole UWB band is separated into four independent bands.Each band has 1,048,576 channels in total,resulting in a spectral resolution of 1 kHz.At 500-3300 MHz,the antenna gain is around 14.3-7.7 K Jy^(-1),the aperture efficiency is around 0.56-0.30,the system temperature is around 88-130 K,and the half-power beamwidth is around 7.6'-1.6'.The measured standard deviation of pointing accuracy is better than~7.9"when zenith angle is within 26.4°.The sensitivity and stability of the UWB receiver are confirmed to satisfy expectations through spectral observations,e.g.,HI and OH.The FAST UWB receiver has already demonstrated good performance in capturing sensitive observations for various scientific goals.

B-Spline-Based Curve Fitting to Cam Pitch Curve Using Reinforcement Learning

Directly applying the B-spline interpolation function to process plate cams in a computer numerical control(CNC)system may produce verbose tool-path codes and unsmooth trajectories.This paper is devoted to addressing the problem of B-splinefitting for cam pitch curves.Considering that the B-spline curve needs to meet the motion law of the follower to approximate the pitch curve,we use the radial error to quantify the effects of thefitting B-spline curve and the pitch curve.The problem thus boils down to solving a difficult global optimization problem tofind the numbers and positions of the control points or data points of the B-spline curve such that the cumulative radial error between thefitting curve and the original curve is minimized,and this problem is attempted in this paper with a double deep Q-network(DDQN)reinforcement learning(RL)algorithm with data points traceability.Specifically,the RL envir-onment,actions set and current states set are designed to facilitate the search of the data points,along with the design of the reward function and the initialization of the neural network.The experimental results show that when the angle division value of the actions set isfixed,the proposed algorithm can maximize the number of data points of the B-spline curve,and accurately place these data points to the right positions,with the minimum average of radial errors.Our work establishes the theoretical foundation for studying splinefitting using the RL method.

MNIST Handwritten Digit Classification Based on Convolutional Neural Network with Hyperparameter Optimization

Accurate handwriting recognition has been a challenging computer vision problem,because static feature analysis of the text pictures is often inade-quate to account for high variance in handwriting styles across people and poor image quality of the handwritten text.Recently,by introducing machine learning,especially convolutional neural networks(CNNs),the recognition accuracy of various handwriting patterns is steadily improved.In this paper,a deep CNN model is developed to further improve the recognition rate of the MNIST hand-written digit dataset with a fast-converging rate in training.The proposed model comes with a multi-layer deep arrange structure,including 3 convolution and acti-vation layers for feature extraction and 2 fully connected layers(i.e.,dense layers)for classification.The model’s hyperparameters,such as the batch sizes,kernel sizes,batch normalization,activation function,and learning rate are optimized to enhance the recognition performance.The average classification accuracy of the proposed methodology is found to reach 99.82%on the training dataset and 99.40%on the testing dataset,making it a nearly error-free system for MNIST recognition.

Assessment of complete lymph node dissection in patients with melanoma:A systemic review and meta-analysis

Background: Complete lymph node dissection(CLND) for patients with melanoma remains controversial. This meta-analysis aimed to compare the prognoses and complications between the CLND and control groups(patients who receive adjuvant treatment or observation only) in patients with sentinel lymph node(SLN)-positive melanoma.Methods: The Pub Med, Embase, Cochrane, and Web of Science databases were searched for cohort studies and randomized clinical trials(RCTs) conducted between 1964 and 2022, and the quality of the studies was assessed using the Cochrane risk-of-bias tool and Newcastle-Ottawa Scale. Hazard ratios(HR) or risk ratios(RR) with 95%confidence intervals(CIs) were calculated for each outcome. Heterogeneity and sensitivity tests were also conducted, and publication bias tests were performed when the pooled number of studies was >10.Results: Fifteen studies, including 11 cohort studies and 4 RCTs, were enrolled and assessed for quality. Analysis of overall survival showed no significant difference between the CLND and control groups(HR=1.02, 95% CI:0.69–1.51, P=0.922). Similarly, recurrence-free survival(HR=0.84, 95% CI: 0.6–1.16, P=0.287), disease-free survival(HR=1.06, 95% CI: 0.65–1.72, P=0.82), and disease-specific survival(HR=0.84, 95% CI: 0.59–1.21,P=0.355) showed no difference between the two groups. CLND did not reduce the risk of recurrence(RR=0.98,95% CI: 0.8–1.2, P=0.851).Conclusion: Remarkably, patients who underwent CLND were more likely to have complications such as flap necrosis and lymphedema than the controls. CLND does not improve patient prognosis and may increase the incidence of complications.

基于建构主义理论基础研究的艺术实践类课程教育思考

文章以建构主义理论为研究对象,建构主义理论在国外的研究起步较早,在教学过程中注重培养被教育者的学习积极性,要求在学习活动中,结合原有经验,在吸收理解新的知识后,通过实践活动不断形成新的认知,建构新的认识思维。文章根据这种教育理念在不同领域的应用,对基于建构主义理论基础研究的高校艺术实践类课程教育进行重点分析。围绕情境的建立、协作能力的培养、会话的应用、意义的建构等四方面,探索目前艺术教学实践课程的特点,提出应用更先进的数字化教学手段,促进教学改革,丰富情境教学形式内容。除此之外,提出建构主义理论对于培养学生认知能力、自主学习能力等的助力,并结合动画周边产品实践课程,对课程中调研环节、设计环节、制作环节、宣传推广环节所对应的情境、协作、会话、意义的建构等进行具体分析。

CDIO与M-Learning理念下艺术类专业创新人才培养途径研究

创新能力提升已成为我国当今时代发展背景下人才培养的必然要求。艺术设计专业正在快速实现跨学科、跨领域的专业整合。创新型人才的培养是我国科技领域、工业领域、服务业领域等多领域人才培养中的重要环节。以OBE为目标导向,运用CDIO教育理念与M-Learning教育理念推动教学模式创新,能够为教育带来更加智慧、深入、宽泛的发展。其教育理念的融合,在艺术类课程的开发与实践中具有重要意义。基于此,文章对CDIO与M-Learning理念下艺术类专业创新人才的培养途径展开研究。

植物甾醇及添加植物甾醇乳制品降低心脑血管疾病风险的功能性评价（英文）

本研究对植物甾醇(phytosterol,PS)、植物甾醇酯(phytosterol ester,PSE)及其相关乳制品进行降低心血管疾病风险方面的功能性评价,并为指导植物性化学物质和养心乳制品(Yangxin dairy,YXD)的实际使用提供科学依据。SD大鼠被分为9组,每组10只。正常对照组、模型组大鼠分别喂养正常饲料和高脂饲料,灌胃0.9%生理盐水,PS、PSE、YXD和安慰剂组高脂喂养的同时连续灌胃PS(23.6、47.2 mg/m L)、PSE(23.6、47.2 mg/m L)、YXD(30、60 g/250 m L)和花生油?4周。4周后处死所有大鼠取样本进行检测。结果发现,大鼠总胆固醇含量明显降低,高密度脂蛋白胆固醇含量呈剂量依赖性增加。这些干预方式会对降低甘油三酸酯的水平、总抗氧化能力和丙二醛含量有一定影响,但效果不稳定。在肝脏和病理切片的相应指标测定结果中也有相同的趋势。PSE和YXD能有效地降低心脑血管疾病风险。此外,本研究证实YXD在降低心血管疾病风险、保护肝脏和血管的效果方面较突出。

嗜酸乳杆菌胞外蛋白调控MAPK和PI3K-AKT信号途径关键蛋白活化水平

探讨并揭示嗜酸乳杆菌(Lactobacillus acidophilus)CICC6005分泌的相关蛋白质促进肠道健康及分子机制具有重要研究价值。本实验在确定了L.acidophilus CICC6005分泌的胞外蛋白抑制HT-29结肠癌细胞增殖的基础上,进一步探讨67 ku和37 ku的胞外蛋白通过何种途径发挥抑制结肠癌细胞增殖。研究以HT-29细胞作为靶细胞,用丝裂原激活的蛋白激酶(mitogen activated protein kinase,MAPK)和磷脂酰肌醇-3激酶-丝氨酸/苏氨酸蛋白激酶(phosphatidylinositol 3-kinase-protein kinase B,PI3K-AKT)信号通路为考察对象,以Western Blotting为手段,分析两个通路中关键的靶点蛋白p38、c-Jun氨基末端激酶(c-Jun N-terminal kinase,JNK)、胞外信号调节激酶(extracellular signal-regulated kinase,ERK)、磷酸化p38(phosphorylated p38,p-p38)、磷酸化c-Jun氨基末端激酶(phosphorylated c-Jun N-terminal kinase,p-JNK)、磷酸化的细胞外信号调节蛋白激酶(phosphorylated extracellular signal-regulated kinase,p-ERK)、磷酸化蛋白激酶B(phosphorylated AKT,p-AKT)、PI3K的表达水平,以探讨并阐述源于L.acidophilus CICC6005胞外蛋白调控结肠癌细胞增殖状况的分子机制。结果表明,不同质量浓度的67 ku和37 ku胞外蛋白分别作用HT-29细胞一定时间后,两种胞外蛋白均具有下调两个信号通路途径中p-ERK1/2、p-p38、p-AKT、PI3K蛋白的表达,且存在浓度依赖关系;但对p-JNK、ERK1/2、p38、JNK蛋白的表达没有影响。因此,源于L.acidophilus CICC6005分泌的37 ku和67 ku胞外蛋白表现出显著的抑制HT-29细胞增殖的功能,其机制可能与调控MAPK和PI3K-AKT两个信号通路中几个关键的靶点蛋白的活化水平相关。该研究结果提示,食用嗜酸乳杆菌其分泌的胞外蛋白质将达到维护肠道健康的目标。

冷却速率对高氮钢焊缝组织和性能的影响

研究了水冷和空冷条件下高氮不锈钢焊缝金属微观组织和力学性能的变化规律,讨论了冷却速率对高氮不锈钢焊缝微观组织和力学性能的影响规律.结果表明,冷却速率增加能够有效增加高氮钢焊缝金属中的氮含量,尤其对于含氮量0.85%的高氮含量焊丝,增氮效果更明显.冷却速率增加对高氮钢焊缝金属抗拉强度提高程度取决于焊丝中的氮含量,对于低氮含量高氮钢焊丝,冷却速率增加能够显著提高焊缝金属抗拉强度,当焊丝中氮含量超过0.58%时,冷却速率增加对焊缝金属抗拉强度影响不大,最终接头强度达到850 MPa.

社会治理共同体的逻辑内涵及形塑路径

建设人人有责、人人尽责、人人享有的社会治理共同体,是新时代推进社会治理现代化的必然要求,是夯实“中国之治”必须认真思索的理论与现实命题。在系统论视域下,社会治理共同体是全体社会成员基于共同利益前提、共同责任担当和共同价值取向等共同意志,旨在协调社会关系、激发社会活力、维护社会秩序、促进社会发展的复杂系统,其蕴含耗散结构、竞争协同、涨落循环等理论特质。形塑社会治理共同体,应走出还原主义与线性逻辑的困境,从治理需要、治理主体、治理方式、治理目标四大子系统构成的有机整体破题,依循整合需要与资源、优化主体与结构、创新方法与手段、强化目标与绩效的系统路径,以合作共治维系社会治理共同体的生命体征及其有序运行。

气相色谱-质谱联用法检测血液中12种新型滥用药物及代谢物

借助衍生化技术,基于气相色谱-质谱联用法,建立了同时检测血液中12种新型滥用药物及其代谢物的定性、定量分析方法。取血液样品适量,采用小体积液-液提取模式,以环己烷为提取溶剂,离心后取上清液,加入吡啶和乙酸酐,微波加热衍生化,衍生化产物经乙酸乙酯提取后,进样分析。结果表明,血液中12种目标物在各自浓度范围内线性关系良好,检出限小于0.005μg·mL^(-1),定量限小于0.01μg·mL^(-1),日内精密度小于7.97%,日间精密度小于8.93%,平均回收率均在90.12%~99.85%之间。实验结果证明,所建立的方法绿色、环保、快速、灵敏、高效、操作简便、实用性强,不仅能为药物滥用检测提供科学理论依据,而且能为打击涉毒违法犯罪活动提供有益帮助。