Spaces with σ-locally Countable Weak Bases

In this paper, by msss_mappings, the relations between metric spaces and spaces with σ _locally countable cs_networks or spaces with σ _locally countable weak bases are established. These are some answers to Alexandroff’s problems.

Weak base favoring the synthesis of highly ordered V-MCM-41 with well-dispersed vanadium and the catalytic performances on selective oxidation of benzyl alcohol

The key to improve the performance of heteroatom catalysts is to ensure the orderliness of catalysts and the good dispersion of heteroatoms.The alkalinity plays the indispensable role in synthetic process of V-MCM-41 catalyst.The excessive alkalinity of synthetic system will make the MCM-41 difficult to crystallize,even to dissolve.It is easy to accumulate for heteroatomic species in the system of low alkalinity.Herein,the highly ordered VMCM-41 with high vanadic content in framework is synthesized in the condition of excessive NH3·H2 O in this paper.A series of characterization results prove the good dispersion of vanadium species,and most of vanadium gets into the framework of MCM-41 with the states of tetravalence and pentavalence.Furthermore,the modified MCM-41 by other transition metals is successful synthesized by the method of V-MCM-41 in this paper.The VMCM-41 shows well catalytic activity for the selective oxidation of benzyl alcohol,which up to 74.83%for the conversion of benzyl alcohol and 96.20%for selectivity of benzaldehyde when initial V/Si=0.10.The paper provides the possibility for industrial application of V-MCM-41 in the oxidation of benzyl alcohol for benzaldehyde.Besides,the work provides a significant idea for the synthesis of modified MCM-41 by well-dispersed transition metals.

THERMODYNAMIC STUDY ON ADSORPTION OF AROMATIC SULFONIC ACIDS ONTO MACROPOROUS WEAK BASE ANION EXCHANGER FROM AQUEOUS SOLUTIONS

The adsorption equilibrium isotherms of three aromatic sulfonic acid compounds, 2-naphthalenesulfonic acid, p-toluenesulfonic acid and p-chlorobenzenesulfonic acid, from aqueous solutions by macroporous weak base anion exchanger within the temperature range of 293 K-313 K were obtained. Several isotherm equations were correlated with the equilibrium data, and the experimental data was found to fit the three-parameter Redlich-Peterson equation best within the entire range of concentrations. The study showed that the hydrophobicity of solute has distinct influence on adsorption capacity of the anion exchanger for the aromatic sulfonic acid. Moreover, estimations of the isosteric enthalpy, free energy, and entropy change of adsorption were also reported. The positive isosteric enthalpy and entropy change for adsorption indicate an endothermic and entropy driven process in the present study.

Spaces with σ-point-discrete N_0-weak bases

It is discussed in this paper the spaces with σ-point-discrete N_0-weak bases. The main results are： （1） A space X has a σ-compact-finite N_0-weak base if and only if X is a k-space with a σ-point-discrete N_0-weak base; （2） Under （CH）, every separable space with a σ-point-discrete N_0-weak base has a countable N_0-weak base.

Vibration diagnostics of weak base embankments

In this paper the theoretical background was analyzed for vibration diagnostics method and experience in its application for weak base embankments. General schemes of survey and recommendations on hardware systems and further prospective development are outlined.

A LEAST SQUARE BASED WEAK GALERKIN FINITE ELEMENT METHOD FOR SECOND ORDER ELLIPTIC EQUATIONS IN NON-DIVERGENCE FORM

This article is devoted to establishing a least square based weak Galerkin method for second order elliptic equations in non-divergence form using a discrete weak Hessian operator.Naturally,the resulting linear system is symmetric and positive definite,and thus the algorithm is easy to implement and analyze.Convergence analysis in the H2 equivalent norm is established on an arbitrary shape regular polygonal mesh.A superconvergence result is proved when the coefficient matrix is constant or piecewise constant.Numerical examples are performed which not only verify the theoretical results but also reveal some unexpected superconvergence phenomena.

QUANTITATIVE ANALYSIS OF VERY WEAK ACID AND BASE BY pH-FIXED TITRATION METHOD

pH-fixed titration method for the determination of weak acids and bases has been studied in this paper.It is not necessary to know the ionization constant of weak acid or base and the concentration of titrant. This method had been applied to determine phenol,4-aminoantipyrine and glycine,whose ionization constants range from 10^(-10)to 10^(-12).The results were satisfactory.

基于模态分解的地基雷达慢速弱目标检测方法

在复杂地物场景中使用地基雷达探测地面动目标时,慢速弱目标与地杂波的频谱通常难以区分,传统的目标检测手段性能受限。针对此问题,提出一种基于模态分解的地基雷达慢速弱目标检测方法。首先设置较低的门限进行单元平均-恒虚警率(cell average-constant false alarm rate,CA-CFAR)检测,初步筛选目标;接着对慢时间信号进行复经验模态分解(complex empirical mode decomposition,CEMD),分离地杂波和动目标;最后利用地杂波和动目标多普勒频谱的对称性差异检测目标。将该检测方法分别与CA-CFAR和正交投影-奇异值分解-恒虚警率(orthogonal projection-singular value decomposition-constant false alarm rate,OP-SVD-CFAR)检测的性能进行比较,并通过仿真数据和两组不同目标的实测数据进行验证。结果表明,所提方法能够提升目标的信杂噪比;在检测概率相同的条件下,其虚警率比CA-CFAR显著降低;在检测概率相同且较高的情况下,所提方法比OP-SVD-CFAR的虚警率也更低,证明了所提方法的有效性。

A Note on Weak Open cs-images of Metric Spaces

In this paper, we prove that a space with a compact Countable weak base if and only if it is a weak open cs-image of a metric space.

非平衡建筑超载下软弱地层地铁深基坑变形特性及加固方案研究

软弱地层中某地铁深基坑外侧作用有建筑物偏压超载,对深基坑开挖存在较为不利影响。为研究外部建筑物偏压超载对软弱地层中基坑支护结构的变形影响,确定合理的隔离桩及基底加固方案,采用有限元方法进行了不同加固方案下基坑开挖模拟计算,并与实测结果对比分析。结果表明:临近深基坑的外部建筑物超载将对基坑支护结构产生明显的偏压效应,偏压超载对坑底软弱地层范围内支护结构影响最为明显;基坑外侧设置隔离桩加固,可有效减小地下连续墙水平位移,隔离桩变形在软弱地层范围最大,增加桩长可使桩底产生支点约束效应,但不能有效减小支护结构位移及支撑轴力;同样,改变隔离桩刚度对支护结构位移及支撑轴力影响较小;仅采用基底加固方案,可减小坑底范围内支护结构位移,但对上部支护结构变形影响较小,采用隔离桩+基底加固组合方案可有效减小支护结构变形及支撑轴力,降低了偏压荷载对基坑的不利影响,具有较好的加固效果。

Base-可数弱θ加细空间

引入了base-可数弱θ加细空间,获得了如下主要结果:(1){F_i}i∈N=∪n∈NA_n是空间X的闭覆盖,且对任意x∈X,■n∈N,使得1≤ord(x,An),若每一闭集F_i(i∈N)是相对于X的base-可数弱θ加细空间,则X是base-可数弱θ加细空间.(2)设f:X→Y是base-可数弱θ加细空间,ω(X)≥ω(Y),如果Y是正则的base-可数弱θ加细空间,那么X是base-可数弱θ加细空间.

Syntheses and Crystal Structures of Two Copper(II) Complexes Derived from Bidentate Schiff Bases

Two new Cu（Ⅱ） complexes have been synthesized with two different bidentate N2O2 donor Schiffbase ligands HL1 （2-（（E）-（4-chlorophenylimino）methyl）-6-bromo-4-chlorophenol） and HL2 （2-（（E）-（2-chlorophenylimino）methyl）-6-bromo-4-chlorophenol）, respectively. Both complexes 1 and 2 have been characterized by elemental analysis and single-crystal X-ray diffraction studies. Structural studies reveal that in both complexes the metal centers are four-coordinated with N202 donor set of Schiff base ligands. Complex 1 belongs to the tetragonal system, space group P4（3）2（1）2 with a = 10.2379（2）, b = 10.2379（2）, c = 24.9623（90） A, V = 2616.41（12） A^3, Z = 4, Dc = 1.908 g/cm^3,μ（MoKa） = 4.3327 mm^-1, F（000） = 1468, S = 0.999, the final R = 0.0345 and wR = 0.0835 for 3506 unique reflections （Rint= 0.0428） with 3249 observed ones （I 〉 2σ（I））. Complex 2 is of monoclinic system, space group P21/c with a = 11.064（3）, b = 9.437（2）, c = 13.277（4） A, fl = 108.997（3）°, V = 1310.8（6） A^3, Z = 2, Dc= 1.904 g/cm^3,μ（MoKa） = 4.319 mm^-1, F（000） = 734, S = 0.997, the final R = 0.0282 and wR = 0.0619 for 3491 unique reflections （Rint = 0.0428） with 2777 observed ones （I 〉 20（I））. The units of the complex are linked via weak interactions, such as C-H…Br hydrogen bonds together with Cl…C1 and Cu…Cl interactions, leading to the formation of one-dimensional chain and two-dimensional network and stabilizing the crystal structure.

Highly sensitive giant magnetoimpedance in a solenoid containing FeCo-based ribbon

The highly sensitive giant magneto-impedance effect in a solenoid containing a magnetic core of Fe36Co36Nb4Si4.sB19.2 （FeCo-based） ribbon under a weak magnetic field （WMF） is presented in this paper. The FeCo-based amorphous ribbon is prepared by single roller quenching and annealed with Joule heat in a flowing nitro- gen atmosphere. The giant magnetoimpedance effect in solenoid （GMIES） profiles are measured with an HP4294A impedance analyzer. The result shows that the CMIES responds to the WMF sensitively （as high as 1580 %/A.m-1）. The high sensitivity can be obtained in a moderate narrow range of annealing current density （30-34 A/mm2） and closely depends on the driven current frequency. The highest sensitivity （1580 %/A.m-1） is obtained when the FeCo- based amorphous ribbon is annealed at 32 A/mm2 for 10 min and then driven with an alterning current （AC） at the frequency of 350 kHz. The highly sensitive GMIES under the WMF may result from the multiple magnetic-anisotropic structure, which is induced by the temperature gradient produced during Joule-heating the ribbon.

Comparative Study between Traditional Approach and Physico-Chemical Approach in Acid Base Disorders Interpretation in Critically Ill Patients

Objective: The traditional approach for acid base interpretation is based on Handerson-Hasselbalch formula and includes Base Excess (BE), bicarbonate (HCO3), albumin corrected anion gap. The Physicochemical approach is centered on the Carbon Dioxide tension (PCO2), the strong ion difference (SID), strong ion gap (SIG) = SID apparent-SID effective and totally weak acids (Atot). The study aims to compare between the traditional approach and the physicochemical approach in acid base disorder interpretation. Design: Prospective observational study in an adult Intensive Care Unit (ICU) recruiting six hundred and sixty one patients. Methods: Arterial blood samples were analyzed to measure pH, PaCO2 sodium, potassium, chloride and lactate. Venous blood samples were analyzed to measure ionized calcium, magnesium, phosphorous and albumin. These samples were interpreted by both techniques. Results: Normal HCO3 and BE were detected by traditional approach in 49 cases of which SIG acidosis was detected in 22 cases (46%) and Hyperchloremic acidosis was detected in 29 cases (60%) by physicochemical method. SIG was elevated in 72 cases (58%) of 124 cases with high anion gap acidosis. SIDeff and BE were strongly correlated, r = 0.8, p 0.0001, while SIG and Albumin corrected Anion Gap (ALAG) were moderately correlated r = 0.56, p Conclusion: Both approaches are important for interpretation of the acid base status. Traditional approach identifies the diagnostic description without many calculations and detects body compensatory response to acid base disorders. Physicochemical approach is essential to identify the exact causation and the severity of the acid base disorders.

两代天基红外传感器对隐身飞机尾焰探测能力分析

为了对比两代天基红外传感器对隐身飞机尾焰的探测能力,以美国SBIRS-GEO和Next-Gen OPIR星座作为研究对象,通过建立高轨红外探测模型以及构建对应的预警探测场景,对两代探测器在不同飞行状态时飞机尾焰的辐亮度响应特性和模拟成像效果进行量化对比.研究结果表明,两代天基红外探测器都可以用来探测飞机尾焰信号;飞机加力对尾焰温度和外形有显著影响,成为影响天基红外传感器探测性能的关键因素;Next-Gen OPIR搭载的新一代传感器可以在36000 km高度捕获和发现处于非加力状态的尾焰,其成像信噪比明显高于SBIRS-GEO传感器对处于加力状态尾焰的信噪比.

Development of key additives for organoclay-free oil-based drilling mud and system performance evaluation

Traditional oil-based drilling muds(OBMs) have a relatively high solid content, which is detrimental to penetration rate increase and reservoir protection. Aimed at solving this problem, an organoclay-free OBM system was studied, the synthesis methods and functioning mechanism of key additives were introduced, and performance evaluation of the system was performed. The rheology modifier was prepared by reacting a dimer fatty acid with diethanolamine, the primary emulsifier was made by oxidation and addition reaction of fatty acids, the secondary emulsifier was made by amidation of a fatty acid, and finally the fluid loss additive of water-soluble acrylic resin was synthesized by introducing acrylic acid into styrene/butyl acrylate polymerization. The rheology modifier could enhance the attraction between droplets, particles in the emulsion via intermolecular hydrogen bonding and improve the shear stress by forming a three-dimensional network structure in the emulsion. Lab experimental results show that the organoclay-free OBM could tolerate temperatures up to 220 ?C and HTHP filtration is less than 5 m L. Compared with the traditional OBMs, the organoclay-free OBM has low plastic viscosity, high shear stress, high ratio of dynamic shear force to plastic viscosity and high permeability recovery, which are beneficial to penetration rate increase, hole cleaning and reservoir protection.

弱光下锑基太阳电池的光谱响应与性能优化

锑基薄膜太阳电池因其制备方法简单,原材料丰富,光电性能稳定等优点而得到了快速发展。其中锑基吸光层材料(硫化锑、硫硒化锑、硒化锑)具有高吸收系数特点,因而在室内或者水下等弱光条件下具有相当大的应用潜力。通过构造两种衰减光谱以研究新型锑基薄膜太阳电池在弱光下的光电响应。首先通过厚度调节硒化锑太阳电池的吸光能力,发现当吸光层厚度较薄时,电池的光电转换效率存在较大差值;而当吸光层厚度过厚时,电池性能又因载流子复合的增大而降低。在吸光层厚度处于合适的0.4~1.2μm之间时,硒化锑太阳电池在长波衰减光谱和短波衰减光谱下都能获得高于16%的转换效率。然后通过硒含量调节锑基太阳电池的光谱吸收范围,发现长波衰减光谱下,锑基太阳电池的器件性能显著高于标准光谱,并且在20%~40%硒含量下能够获得最佳的转换效率。而在短波衰减光谱下,锑基太阳电池的最佳性能出现在硒含量为60%的情况下。因而在弱光条件下,锑基太阳电池的最佳硒含量需要通过具体的光谱特性确定。最后研究了两种衰减光谱下,硫化锑/硒化锑双结叠层太阳电池的光谱响应特性。发现在短波衰减光谱下,叠层太阳电池效率会随着总厚度的增加而增加。而在长波衰减光谱下,叠层太阳电池的最佳性能能够一直保持在较高水平。当叠层电池总厚度为2μm,且硫化锑顶电池厚度在0.5~1.2μm之间时,器件在两种衰减光谱下都能够实现光谱能量在两个子电池中的合理分配,使得叠层电池效率能够保持在20%以上。通过该研究对锑基太阳电池器件结构的合理设计,能够保证单结和双结器件在不同弱光条件下的高性能输出,为高环境适应性的锑基薄膜太阳电池的研发提供技术支持。

脂肽复配弱碱三元驱油体系性能评价

为了在稳定经济成本的同时进一步提高弱碱三元体系的驱油能力,在弱碱三元体系的理论研究基础上,采用来源广泛的环境友好型生物表面活性剂脂肽与石油磺酸盐按照1∶1的比例复配形成新三元体系,开展体系评价并进行室内驱替实验。结果表明,脂肽复配弱碱三元体系在4次吸附后界面张力仍能保持在10^(-3)mN·m^(-1)数量级,表现出优秀的抗吸附能力;脂肽复配弱碱三元体系的界面张力可以在较低的Na_(2)CO_(3)溶液浓度条件下达到10^(-3)mN·m^(-1)数量级,界面活性优异;30min内乳状液稳定性良好;室内驱油实验中采收率达73.89%,较弱碱三元体系采收率提高4.59%。实验结果对现场的化学驱开发具有一定借鉴意义。

脓毒症患者ICU获得性衰弱预防与管理的最佳证据

目的:目前关于脓毒症患者重症监护病房获得性衰弱(intensive care unit-acquired weakness,ICU-AW)防治效果的研究不尽相同,且缺乏系统有效的循证护理方案。本研究基于循证护理理念对脓毒症患者ICU-AW预防与管理的证据进行检索、分析和整合,以期为临床护理实践提供理论依据。方法:系统检索英国国家卫生与临床优化研究所指南网、美国国立指南网、BMJ最佳临床实践、国际指南协作网、苏格兰院际指南网、加拿大安大略注册护士协会指南网、乔安娜布里格斯研究所循证卫生保健中心数据库、PubMed、Embase、CINAHL、UpToDate、Cochrane Library、Scopus、中国知网、万方数据库、维普数据库、中国生物医学文献数据库、医脉通关于脓毒症患者ICU-AW预防与管理的临床指南、最佳实践信息手册、临床决策、证据总结、系统评价、专家共识、随机对照研究等。检索时限为建库至2024年2月5日。2名研究人员对纳入文献进行质量评价,按纳入和排除标准对相关文献进行证据提取与分析。结果:最终纳入13篇文献,其中6篇随机对照研究,3篇指南、2篇系统评价、2篇专家共识,形成25条证据,包含ICU-AW的诊断方法、康复技术开始的时机、康复技术实施前的评估、康复技术实施的方法、安全评价标准、安全性及可行性、健康教育7个主题。结论:本研究总结了脓毒症患者ICU-AW预防及管理的相关策略,临床医护人员可根据实际情境个性化地引用相关证据,以实现对脓毒症患者ICU-AW防治的科学管理。

基于跨理论模型的运动康复方案在老年ICU获得性衰弱病人中的应用

目的:探讨基于跨理论模型的运动康复方案在老年重症监护室(ICU)获得性衰弱(ICU-AW)病人中的应用效果。方法:于2023年1月—6月选取江西省某三级甲等医院ICU病人82例为研究对象,按照入院顺序分为对照组(n=41)和观察组(n=41)。对照组采用常规护理,观察组在其基础上采用基于跨理论模型的运动康复方案,于干预前、干预1个月和3个月后比较两组病人的健康状况、运动自我效能、运动康复依从性及ICU-AW发生率。结果:干预1个月后,两组病人的健康状况、运动自我效能、运动康复依从性和ICU-AW发生率比较,差异均无统计学意义(P>0.05);干预3个月后,观察组健康状况、运动自我效能、运动康复依从性优于对照组,ICU-AW发生率低于对照组,差异均有统计学意义(P<0.05);且两组病人健康状况,运动自我效能和运动康复依从性比较,组间效应、时间效应及交互效应均有统计学意义(P<0.05)。结论:基于跨理论模型的运动康复方案可有效改善老年ICU-AW病人的健康状况和运动康复自我效能,提高康复依从性,降低ICU-AW发生率。