Modeling of thermal conductivity and density of alumina/silica in water hybrid nanocolloid by the application of Artificial Neural Networks

In this research work, the thermal conductivity and density of alumina/silica(Al_2O_3/SiO_2) in water hybrid nanofluids at different temperatures and volume concentrations have been modeled using the artificial neural networks(ANN). The nanocolloid involved in the study was synthesized by the two-step method and characterized by XRD, TEM, SEM–EDX and zeta potential analysis. The properties of the synthesized nanofluid were measured at various volume concentrations(0.05%, 0.1% and 0.2%) and temperatures(20 to 60 °C). Established on the observational data and ANN, the optimum neural structure was suggested for predicting the thermal conductivity and density of the hybrid nanofluid as a function of temperature and solid volume concentrations. The results indicate that a neural network with 2 hidden layers and 10 neurons have the lowest error and a highest fitting coefficient o thermal conductivity, whereas in the case of density, the structure with 1 hidden layer consisting of 4 neurons proved to be the optimal structure.

Stability of Soil and Biosolid Nanocolloid and Macrocolloid Particles in the Absence and Presence of Arsenic, Selenium, Copper and Lead

Due to their enhanced stability and contaminant transport potential, environmental nanoparticles derived from soil and biosolid materials may pose a considerable risk to groundwater quality. Very little information exists on the stability and transportability of environmental or natural nanocolloids in the presence of As, Se, Pb and Cu contaminants, all of which are considered to represent substantial threats to human and animal populations through groundwater contamination. This study involved stability settling experiments of nanocolloids (NCs) (<100 nm) and macrocolloids (MCs) (100 - 2000 nm) fractionated from Bt horizons of three Kentucky soils and one biosolid waste material in water suspensions of 0, 2, and 10 mg·L-1 of As, Se, Pb and Cu. The results indicated greater stability in the mineral than the biosolid colloid fractions, and enhanced stability of NCs over corresponding MCs in the presence or absence of contaminants at low contaminant loads. At high contaminant loads nearly all colloids were unstable except for the bio-nanocolloids which still sustained considerable stability. At low contaminant loads, the MC fraction stability sequence was smectitic > mixed > kaolinitic > biosolid. Among the nano-fractions, the smectitic and kaolinitic colloids demonstrated lower stability than the MCs, but higher than those of the mixed and biosolid fractions. Physicochemical characterizations indicated that extensive organic carbon surface coatings and higher Al/Fe:Si ratios may have induced higher stability in the NC fractions, but their overall stability may also have been hindered in some cases by nano-aggregation phenomena.

Curative effect of hydrogen peroxide combined with silver ion disinfection on pelvic floor dysfunction

BACKGROUND Pelvic floor dysfunction(PFD)is related to muscle fiber tearing during childbirth,negatively impacting postpartum quality of life of parturient.Appropriate and effective intervention is necessary to promote PFD recovery.AIM To analyze the use of hydrogen peroxide and silver ion disinfection for vaginal electrodes in conjunction with comprehensive rehabilitation therapy for postpartum women with PFD.METHODS A total of 59 women with PFD who were admitted to the hospital from May 2019 to July 2022 were divided into two groups:Control group(n=27)received comprehensive rehabilitation therapy and observation group(n=32)received intervention with pelvic floor biostimulation feedback instrument in addition to comprehensive rehabilitation therapy.The vaginal electrodes were disinfected with hydrogen peroxide and silver ion before treatment.Intervention for both groups was started 6 weeks postpartum,and rehabilitation lasted for 3 months.Pelvic floor muscle voltage,pelvic floor muscle strength,vaginal muscle voltage,vaginal muscle tone,pelvic floor function,quality of life,and incidence of postpartum PFD were compared between the two groups.RESULTS Before comprehensive rehabilitation treatment,basic data and pelvic floor function were not significantly different between the two groups.After treatment,the observation group showed significant improvements in the maximum voltage and average voltage of pelvic floor muscles,contraction time of type I and type II fibers,pelvic floor muscle strength,vaginal muscle tone,vaginal muscle voltage,and quality of life(GQOLI-74 reports),compared with the control group.The observation group had lower scores on the pelvic floor distress inventory(PFDI-20)and a lower incidence of postpartum PFD,indicating the effectiveness of the pelvic floor biostimulation feedback instrument in promoting the recovery of maternal pelvic floor function.CONCLUSION The combination of the pelvic floor biostimulation feedback instrument and comprehensive rehabilitation nursing can improve pelvic floor muscle strength,promote the recovery of vaginal muscle tone,and improve pelvic floor function and quality of life.The use of hydrogen peroxide and silver ion disinfectant demonstrated favorable antibacterial efficacy and is worthy of clinical application.

Molecular dynamics simulation for aggregation phenomena of nanocolloids

Nonequilibrium molecular dynamics (MD) method was used to study the dielectrophoresis (DEP) motion of nanocolloids in non-uniform electric field. By changing the electric field strength and system temperature, aggregation phenomena of nanocolloids was analyzed. Simulation results showed that at normal temperature, though the Brownian force can affect the motion of colloids, the attractive force will increase quickly with the distance between colloids down to 12σ , which makes colloids aggregate. When the Brownian force is weak to colloid's motion, for the enhancement of electric field strength, the DEP force of colloid will increase and so did the attractive force, which finally quickens the aggregate speed. Simulation results also showed that the temperature' enhancement will increase the Brownian force of colloids, hence disturbing the colloids aggregation. Moreover, the DLVO theory was used to study the motion of a pair of interactional colloids, both the potential energy and the attractive force versus distance of colloids were presented, then the latter graph was used to compare with another graph elicited by MD method. Results showed that the two graphs were nearly the same, indicating the MD model accorded with the theory.

MAGNETIC POLYMER MICROSPHERE STABILIZED GOLD NANOCOLLOIDS AS A FACILELY RECOVERABLE CATALYST

Magnetically responsive hierarchical magnetite/silica/poly（ethyleneglycol dimethacrylate-co-4-vinylpyridine） （Fe3O4/SiO2/P（EGDMA-co-VPy）） tri-layer microspheres were used as stabilizers for gold metallic nanoeolloids as a facilely recoverable catalyst with the reduction of 4-nitrophenol to 4-aminophenol as a model reaction. The magnetic microsphere stabilized gold metallic nanocolloids were prepared by in situ reduction of gold chloride trihydrate with borohydride as reductant via the stabilization effect of the pyridyl groups to gold nanoparticles on the surface of the outer shell-layer of the inorganic/polymer tri-layer microspheres.

Viscosity and aggregation structure of nanocolloidal dispersions

In this work,the effects of nanoparticle size,particle volume fraction and pH on the viscosity of silicon dioxide nanocolloidal dispersions are investigated.Both size and pH are found to significantly affect nanocolloid viscosity.Two models are used to study the effect of aggregate structure on the viscosity of the nanocolloidal dispersion.The fractal concept is introduced to describe the irregular and dynamic aggregate structure.The structure of aggregates,which is considered to play an important role in viscosity,is affected by both intermolecular and electrostatic forces.The particle interaction is primarily affected by particle distance and becomes stronger with decreasing particle size and increasing volume fraction.The aggregate structure is also affected by the pH of the solution.Studying the relationship between pH and zeta-potential shows that with the neutralization of charges on the particle surface and decreasing electrical repulsion force,the particle interaction becomes dominated by attractive forces and the aggregates form a more compact structure.

原子力显微镜表征土壤中的纳米胶体

以平均粒径和多分散性指数为参数、采用原子力显微镜(AFM)表征了不同地区三种土壤纳米胶体的粒径与形貌,研究了pH及重金属离子对纳米胶体粒径和形貌的影响。结果表明,江苏九华(JH-4)土壤纳米胶体主要为形状规则的黏土矿物粒子,并部分被有机质包裹或覆盖,平均粒径为21.5nm(n=98),多分散性程度高(PI=1.9);浙江富阳(FY-1)土壤纳米胶体主要是无规则形状的有机质包裹的粒子,平均粒径为20.3nm(n=133),多分散性程度高(PI=2.0);江西德兴(DX-9)土壤纳米胶体主要是球状或近球状的无机粒子,平均粒径为56.3nm(n=147),多分散性程度较低(PI=1.3)。pH及重金属铜离子的存在对纳米胶体粒径和形貌会产生或分散或团聚的影响,这种影响可能与土壤纳米胶体的电荷性质、有机质含量等因素有关,形貌变化较为复杂。这种复杂性对理解和研究胶体在环境过程中的行为具有指导意义。

纳米粒子介电泳的分子动力学模拟

为研究微流体环境下纳米粒子的介电泳现象并分析其介电泳特性,采用非平衡态分子动力学方法对纳米胶体粒子及其周围溶剂粒子进行建模.介电泳模拟之前,通过对系统能量和温度的趋衡过程进行模拟,使纳米胶体所处的微流体系统达到稳定状态,并得出系统能量以及温度变化过程的趋衡图.对纳米胶体模型施加非均匀电场,使胶体电偶极化.变化非均匀电场强度,研究胶体模型失效的一般规律.发现随着非均匀电场强度的增加,小离子有不断脱离大离子表面的趋势,胶体模型失效的临界电场强度参数为E0=15ε/(eσ).此外,对不同极性的纳米胶体的介电泳现象进行模拟,发现在正介电泳情况下,胶体的电偶极距不断增大,且电偶极距大的胶体有较大的介电泳速度和位移.

Rapid synthesis of highly active Pt/C catalysts with various metal loadings from single batch platinum colloid

A series of Pt/C catalysts for proton exchange membrane fuel cells(PEMFCs) with various metal loadings is synthesized by a microwave-assisted polyol process via mixing an extremely stable platinum colloid(> 3 months’ shelf life) from single batch preparation with activated carbon ethylene glycol suspension.21 wt%, 42 wt% and 61 wt% Pt loadings are employed to showcase the advantages of the improved polyol process. The ultraviolet(UV)–visible spectra and ζ-potential measurements are conducted to monitor the wet chemistry process during catalyst preparation. The powder X-ray diffraction(XRD), transmission electron microscopy(TEM) and thermogravimetric analysis(TGA) characterizations are carried out on catalysts. The catalyst activities are investigated using electrochemical and single cell tests. The stability of Pt nanoparticle colloid is explored by ORR, cyclic voltammetry(CV) and ζ-potential measurements. The TEM results show the Pt particle sizes of the colloid, and the sizes of the 21 wt%, 42 wt% and 61 wt%Pt/C samples are 2.1–3.9 nm. Because of the high Pt dispersion, the Pt/C catalysts exhibit superior electroactivity toward ORR. In addition, four 61 wt% Pt/C catalysts made from the Pt colloid with 0–3 months’ shelf life show almost the same performance, which exhibits superior stability of the Pt colloid system without surfactant protection.

^(188)Re-硫化锑纳米胶粒的制备及其被兔淋巴结摄取的实验研究

制备了两种不同粒径的硫化锑纳米胶粒 ,研究了1 88Re标记两种胶粒的条件以及标记物被兔窝淋巴结和腹股沟淋巴结摄取的情况。实验结果表明 ,两种硫化锑纳米胶粒的平均粒径分别为 10 .2nm和 4 4 .7nm。当SnCl2 ·2H2 O的浓度为 4mg mL ,抗坏血酸的浓度为 6mg mL时 ,加入适量的1 88ReO-4淋洗液 ,6 0℃水浴加热 6 0min ,标记率均大于 95 % ,而且有较好的体外稳定性。从正常的新西兰大白兔双足趾蹼皮下分别注射两种标记物 ,γ探针探测的结果表明 ,窝淋巴结对 10 .2nm和 4 4 .7nm胶粒的摄取在注射后 1.5— 2h之间达到最大值 ,分别占各自注入量的17.4 %和 19.4 % ;腹股沟淋巴结对 10 .2nm和 4 4 .7nm胶粒的摄取在注射后 2h左右达到最大值 ,分别占各自注入量的 4 .7%和 4 .2 %。

药用载体——硫化亚锑钠米胶粒的制备及表征

采用两种不同的硫源 ,制备了两种不同粒径分布的药用载体——硫化亚锑纳米胶粒。透射电镜 (TEM)和原子力显微镜 (AFM)表征显示 ,两者的平均粒径分别为 1 0 nm和 40 nm,且均为球形颗粒。

纳米铜胶的原位合成及其摩擦学性能研究

以醋酸铜为母体，维生素C（Vc）为还原剂，吐温-80为修饰剂，用原位合成一步法在基础油液体石蜡中成功制备了粒径分布为2．3—9．5nm、平均粒径为4．3nm的纳米铜胶。以制备的纳米铜胶的液体石蜡为润滑油添加剂，将其分散于关孚1号5w-30全合成机油中，制得分散稳定性、兼容性优良的纳米润滑油，在UMT-II摩擦磨损实验机、四球摩擦磨损实验机上分别考察添加纳米铜胶的润滑油的摩擦学性能，利用扫描电镜（SEM）和能谱散射光谱（EDS）分析磨损表面形貌，结果表明，添加的纳米铜胶在摩擦表面的划痕和犁沟处沉积并铺展成膜，相比关孚1号5w-30全合成机油，较大程度地降低了摩擦副的摩擦因数，显著改善了润滑油的润滑性能，表现出优异的抗磨减磨性能、极压性能和极限工作能力等摩擦学性能。

硅钼黄分光光度法测定柠檬酸液中的溶硅

基于硅钼黄分光光度法建立了分析柠檬酸液中溶硅的方法,探讨了柠檬酸浓度、钼酸铵浓度、柠檬酸与钼酸铵浓度比、盐酸浓度和显色时间对硅钼黄络合物吸光度的影响。研究表明,反应体系为CCA/CAM=1/3,HCl浓度为0.35 mol/L,低于3.0%的柠檬酸液中显色10 min。在λ=410 nm处,吸光度(A)与质量浓度(C)成线性关系,Si的量在0.1～16.0 mg/L内符合比尔定律,硅的测定回归方程为A=0.030+0.060C(R2=0.998 2),其检出限为0.1 mg/L,方法重复性的RSD和精密度均小于1.0%,加标回收率为99.5%～102.4%。此法快速、简便,可准确分析柠檬酸液中的溶硅。

全新的化妆品活性成份的稳定超微载体Nanotope^(TM)——纳能托~[注]及其与普通脂质体的性能比较

介绍了一种全新的平均粒径为２５ｎｍ左右的化妆品活性物的超微载体系统ＮａｎｏｔｏｐｅＴＭ（纳能托［注］）。它对皮肤具有高覆盖率和强渗透性。它比普通脂质体更耐表面活性剂，并具有良好的ｐＨ值和离子强度的适应性，是一种比脂质体、纳球、纳颗粒以及纳乳液都稳定且粒径分布均匀的纳胶体。运用动态光散射法及浊度法研究了ＮａｎｏｔｏｐｅＴＭ（纳能托［注］）及脂质体在一系列不同表面活性剂中的稳定性及其粒径分布。讨论了该超微载体系统的应用前景。

一种泥质软岩隧道纳米硅溶胶-铝酸盐水泥复合浆材设计及性能优化分析

针对泥质软岩隧道注浆加固需求以及常用单一浆材性能存在的弊端,将纳米硅溶胶和铝酸盐水泥作为主剂,按照硅溶胶∶水∶铝酸盐水泥为100 mL∶100 mL∶120 g的基本配比组成复合注浆材料进行研究。初期研究发现,简单将纳米硅溶胶与铝酸盐水泥复合会导致结石率低且结石体存在裂缝等问题。针对结石率问题,选取硅酸钠和硅酸盐水泥,研究各自掺量对结石率、3 d抗压强度和凝胶时间的影响规律,在满足结石率达到100%的前提下,以3 d抗压强度为主、凝胶时间为辅,综合得出硅酸钠为提高结石率的优选外加剂,推荐掺量为铝酸盐水泥的1%。然后,将硅酸钠掺量1%作为常规配比用于后续试验。针对开裂问题,选取硅灰、氧化镁、氧化钙和可再分散乳胶粉,研究各自掺量对裂缝、3 d抗压强度和凝胶时间的影响规律。在满足裂缝得到完全治理的前提下,以3 d抗压强度和凝胶时间为参考依据,得出氧化镁为防治开裂的优选外加剂,推荐掺量为铝酸盐水泥的0.6%。最后,基于界面过渡区理论,评估优化浆材对滇中引水香炉山隧洞泥岩的加固效果。结果表明,岩-浆界面过渡区宽度平均仅88.6μm,显微硬度下降幅度较小,岩-浆结合处微结构较紧固。

改性木质素磺酸钠基竹叶黄酮纳米胶体球的制备及防晒性能

采用自组装法,以竹叶碳苷黄酮(BLF_(70))为芯材,改性木质素磺酸钠(LS/CTAB)为壁材,在无水乙醇-正己烷体系中自组装制备纳米混悬液(NS_(LS/BLF)),添加1%的壳聚糖(CS)作为降色剂,真空冷冻干燥得纳米胶体球冻干粉(NS_(LS/BLF/CS))。结果表明,NS_(LS/BLF/CS)呈白色细粉状,色泽均匀,平均粒径为(402.5±21.0)nm,分散系数为0.351±0.006,平均电位为(-22.1±1.47)mV,包埋率为(80.57±0.55)%。与BLF_(70)相比,NS_(LS/BLF/CS)具有更好的紫外吸收性。本研究开发的NS_(LS/BLF/CS)有望成为商业性能良好的新型复合防晒功能因子。

Rapid detection of cordycepin in food by surface-enhanced Raman technique

In this paper,a method for rapid detection of cordycepin in food was established based on surface-enhanced Raman spectroscopic analysis method.The surface-enhanced Raman substrates were screened and the Raman detection conditions and sample pretreatment methods were optimized.The optimal substrate was gold nanocolloid,and the optimal detection conditions were as follows:the addition amount of gold nanocolloid was 200μL of gold nanocolloid and the sample addition amount was 5μL.Under the optimal conditions,the detection limit of cordycepin was 1 mg/L,and the sample pretreatment was performed by methanol extraction.Based on the established surface-enhanced Raman spectroscopy(SERS)method,cordycepin in two Cordyceps militaris was detected,which confirmed the practical application of this method.

TiO2硅油-微孔陶瓷自润滑材料制备

在对微孔陶瓷纳米胶体浸渍动力学理论分析的基础上,采用浸渍工艺制备出TiO2硅油-微孔陶瓷自润滑材料,并对其摩擦学性能进行了实验研究。研究结果表明:纳米胶体的浸渍效果与TiO2硅油纳米胶体的特性和微孔陶瓷基体的特性决定,同时还受到浸渍中的温度、压力、时间等参数的影响。TiO2硅油纳米胶体具有良好的浸渍特性,在微孔陶瓷孔隙率为22%时,浸渍制备得到的TiO2硅油-微孔陶瓷自润滑材料平均含油率为19%。与浸渍纯硅油相比该材料具有更加优异的自润滑性能,当胶体浓度为0.5wt%时,摩擦系数保持在0.07左右,在摩擦过程中纳米颗粒释放到接触表面,起到"微滚珠"作用,改善硅油的润滑效果。