Effect of ZrO2 Nanoparticles Additive on the Tribological Behavior of Multialkylated Cyclopentanes

Monodisperse ZrO₂ nanoparticles with a particle size of about 6–7 nm and low volatile multialkylated cyclopentanes (MACs) lubricant were prepared and characterized. The effect of ZrO₂ nanoparticles as additive on the friction and wear behavior of MACs base oil was investigated. The friction and wear performance of 2 wt% ZrO₂ nanoparticles + MACs was evaluated using an Optimal SRV oscillating friction and wear tester, with a steel ball sliding against the same steel counterpart disc. Results indicate that the wear resistance and load-carrying capacity of MACs base oil were markedly raised and its friction coefficient changed little when 2 wt% ZrO₂ nanoparticles were added to it.     

Channel correlation of transmit diversity FSO systems with partially coherent optical beams

Spatial diversity, including transmit diversity, has been proven to be a promising technique to mitigate turbulence-induced signal fading. However, due to the limitation of size in compact FSO (free-space optical) terminals, the transmit antennas cannot always be separated far enough from each other, resulting in increased channel correlation and deteriorated diversity performance. In this paper, we focus on the channel correlation statistics of transmit diversity FSO systems with two transmit beams. Specifically, we consider partially coherent optical beams, which reduce scintillation over fully coherent optical beams. We perform theoretical analysis and obtain some interesting numerical results, such as the degree of channel correlation which changed mainly with source correlation radius from 0.001 to 0.1 m. These results can be helpful for designing transmit diversity FSO systems with partially coherent beams.     

远红外烤制对烤鱼品质及多环芳烃含量的影响

为了改善烤鱼的质构特性等食用品质,减少多环芳烃的形成,以草鱼为对象,研究传统炭烤和远红外烤制方式对烤鱼质构特性及多环芳烃含量的影响。结果表明：传统炭烤和远红外烤制对烤鱼的食用品质有不同影响,与传统炭烤鱼肉相比,远红外烤制鱼肉硬度显著降低（P＜0.05）,且剪切力均显著低于传统炭烤组（P＜0.05）,能够显著改善烤制鱼肉的嫩度;相对而言,远红外烤制鱼肉具有更优的质构特性;远红外烤制能显著降低烤鱼肉中PAH4（苯并(a)蒽、?、苯并(k)荧蒽、苯并(a)芘）和PAH16（萘、苊烯、苊、芴、菲、蒽、荧蒽、芘、苯并(a)蒽、?、苯并(b)荧蒽、苯并(k)荧蒽、苯并(a)芘、茚苯(1,2,3-c,d)芘、二苯并(a,h)蒽、苯并(g,h,i)芘）的生成量（P＜0.05）,与传统炭烤鱼肉相比,PAH4和PAH16总生成量分别下降39.07%和44.07%。     

高通量测序技术分析鸭皮中耐热菌群

鸭皮作为肉制品中常用的添加原料,其在不同热杀菌处理状态下的微生物多样性研究非常重要。将鸭皮分别在60、70、80、90、100、110、120℃条件下热处理后25℃恒温放置1周,通过高通量测序分析鸭皮的微生物多样性。结果表明:60℃热处理的鸭皮中主要菌属为假单胞菌属(33.52%)和不动杆菌属(18.55%),70℃热处理的鸭皮中主要菌属为不动杆菌属(18.46%)、狭义厌氧梭菌属18(12.41%)、变形杆菌属(11.04%)、假单胞菌属(10.17%)、狭义厌氧梭菌属7(8.62%),80、90℃热处理的鸭皮中优势菌属为狭义厌氧梭菌属18,相对丰度分别为63.04%和84.11%,100℃热处理组优势菌属为芽孢杆菌属(49.50%)、狭义厌氧梭菌属18(29.19%)和厌氧杆菌属(17.20%),110℃热处理组优势菌属为芽孢杆菌属(99.23%),120℃热处理组优势菌属为狭义厌氧梭菌属18(52.41%)、芽孢杆菌属(33.07%)和狭义厌氧梭菌属7(12.23%);样品聚类和β-多样性分析表明,温度对鸭皮中的细菌群落组成和丰度差异影响较大。     

姜黄素联合乙二胺四乙酸对荧光假单胞菌的光动力灭活作用

为探讨姜黄素对荧光假单胞菌的光动力灭活（photodynamic inactivation,PDI）作用,提高光动力杀菌效果,本研究以乙二胺四乙酸（ethylene diamine tetraacetic acid,EDTA）为协同剂,对PDI的应用条件进行优化,探讨姜黄素联合EDTA对荧光假单胞菌生物膜的PDI作用,并进一步将姜黄素联合EDTA应用于新鲜猪肉的保鲜。结果表明,与空白组相比,0.5%（质量分数,下同）EDTA与75 μmol/L 姜黄素经光照（功率密度200 mW/cm2、波长460 nm、光照时间20 min）,荧光假单胞菌的菌落数对数值减小了6.40（lg（CFU/mL））,玻璃及丙烯腈二乙烯丁二烯树脂（acrylonitrile-butadiene-styrene,ABS）板表面生物膜中荧光假单胞菌菌落数对数值分别减小4.57、6.60（lg（CFU/mL））,均显著高于单独使用姜黄素组的灭活效果（P＜0.05）。新鲜猪肉经75 μmol/L姜黄素和0.5% EDTA处理并光照后（功率密度100 mW/cm2、波长460 nm、光照时间20 min）,与空白组相比,保存到第10天其表面荧光假单胞菌菌落数对数值减小3.05（lg（CFU/mL））,质量损失率为2.14%,色差ΔE随姜黄素浓度增加而增大;且处理后的猪肉随贮藏时间的延长pH值变化缓慢。说明PDI处理对猪肉的感官品质影响较小,能较好地维持猪肉pH值,对猪肉表面荧光假单胞菌有显著抑制作用。结论：姜黄素联合EDTA的PDI处理显著延长了猪肉的保鲜期,本研究可为光动力技术在食品杀菌及贮藏保鲜中的应用提供新的理论参考和技术支持。     

Hybrid finite-difference/finite-volume time-domain analysis formicrowave integrated circuits with curved PEC surfaces using anonuniform rectangular grid

In this paper, we present a hybrid algorithm that combines the finite-difference time-domain (FDTD) and finite-volume time-domain (FVTD) methods to analyze microwave integrated-circuit structures that may contain curved perfect electric conductor (PEC) surfaces. We employ the conventional nonuniform FDTD in regions where the objects are describable with a rectangular mesh, while applying the FVTD method elsewhere where we need to deal with curved PEC configurations. Both the FDTD and FVTD quantities are defined in the mutually overlapping regions, and these fields from the respective regions are interpolated by using their nearest neighbors. We validate this algorithm by analyzing the scattering parameters of a stripline with one or more adjacent cylindrical vias, whose geometries are frequently encountered in printed-circuit-board designs. It is found that the hybrid FDTD-FVTD approach requires little increase in central processing unit time and memory in comparison to the conventional FDTD, while its computational accuracy is significantly improved over a wide range of frequencies. Specifically, this accuracy is found to be comparable to that achieved by doubling the mesh density of the staircased FDTD     

一种新颖的单线阵CCD双坐标自准直仪

本文提出了一种采用单线阵 CCD器件应用自准直原理实现二维小角度测量的全新方案 ,即利用单线阵 CCD测量二维小角度 ,使瞄准和测量一次完成并具有一定的测试频响 ;给出了测量原理及系统硬件、软件设计。实验表明 ,所研制的单线阵 CCD双坐标自准直仪量程± 5角分 ,分辨力优于 0 .3角秒 ,测量精度优于 1角秒     

对少气缸发动机曲轴平衡特性的分析比较

本文从曲轴平衡的力学模型、平衡计算和现有机型的平衡方案等诸多方面对少气缸发动机的曲轴平衡特性进行了分析比较 ,所得结论对发动机的设计选型和实施平衡方案具有一定的参考价值。