复合材料三明治结构板的电磁和冲击性能分析

为开发兼有反雷达侦察及减缓冲击波对乘员伤害能力的新型装甲板,设计了一种上面板、核层和下面板分别为玻璃纤维复合材料、聚氨酯/多壁碳纳米管复合材料功能梯度泡沫和碳纤维复合材料的全新三明治结构,该结构既能吸收电磁波又能阻隔冲击波的传递;建立了该结构的电磁波反射和冲击波透射理论模型,考察泡沫核层梯度模式和层厚对电磁波反射系数和冲击波透射系数的影响,并采用NSGA-Ⅱ算法对装甲板结构参数进行多目标优化.结果表明,优化后该结构的电磁波反射系数降低了94.58%,冲击波透射系数降低了4.35%,说明其具有良好的电磁波吸收能力和冲击波阻隔能力.

行人下肢有限元模型的建立与验证研究

下肢损伤是行人与车辆碰撞事故中的主要损伤形式之一,建立具有较高生物逼真度的行人下肢有限元模型,可以为下肢保护提供有效的研究手段.在下肢长骨(股骨、胫骨、腓骨)、韧带(ACL,PCL,MCL,LCL)及膝关节得到全面验证的基础上,建立了包含骨骼、韧带、肌肉及皮肤等详细解剖学结构的行人下肢有限元模型,并定义了各组织间的接触.利用行人下肢弯曲的生物力学实验,对下肢有限元模型进行了整体弯曲验证.结果显示,下肢有限元模型的损伤形式、损伤发生时刻、膝关节弯矩和弯曲角度均与实验结果吻合较好,能够较真实地反映行人下肢的损伤和生物力学响应,具有较好的生物逼真度.

行人膝关节韧带的建模及验证研究

基于人体模型THUMS中的膝韧带模型,改进了材料参数和单元属性。采用近年较新的生物力学实验数据,逐个验证韧带模型在不同应变率下的生物逼真度。结果表明,膝韧带ACL、PCL、MCL和LCL在不同应变率下的拉力与位移关系曲线与试验结果吻合较好,说明模型具有较好的生物逼真度,能较准确地模拟韧带的损伤和拉伸响应。

汽车碰撞事故中下肢的损伤容限与机制

为开展汽车碰撞事故的实验分析和数值建模,综述了下肢的损伤容限数据和损伤机制。被选文献起1859年的自股骨三点弯曲试验数据(Weber),直至2009年的行人下肢多刚体建模数据(Kerrigan)。数据表明:在汽车碰撞事故中下肢损伤较为多见,其症状常常为大面积软组织撕裂或缺损,并伴有严重骨折或脱位。对于股骨、髌骨、膝关节、胫骨和踝关节等下肢部位,比较了在静态、动态条件下的弯矩、扭矩、轴向压缩力的损伤容限数据。对于膝关节伤、长骨干骨折、股骨颈骨折、股骨髁骨折、踝关节骨折、脚骨骨折等典型伤类,讨论了下肢撞击的损伤机制。

交通事故中颈部损伤的有限元模型研究现状

汽车交通事故是当今世界造成儿童和年轻人死亡的主要原因,其中头颈部的损伤是交通事故中最为常见的致命性损伤。由于碰撞条件复杂和不可重复,再加上尸体和动物研究的伦理问题,致使头颈部损伤机理的实验研究存在较大困难,因此有限元分析在人体头-颈部耐撞性研究得到广泛应用。有限元方法的应用对于交通事故中不同撞击条件损伤程度的评估以及汽车工业损伤保护标准的开发起重要作用。本文从头颈部损伤机理、有限元几何模型获取、有限元网格划分,及所研究材料特性和实验验证方法等方面,对近年来国际上开发的应用有限元模型对交通事故中的头颈部损伤的研究现状进行综述,并对各个模型的优势和特点加以分析归纳,并对未来相关研究提出建议。

Solid Acid Used as Highly Efficient Catalyst for Esterification of Free Fatty Acids with Alcohols

Anovel solid acid catalyst, which was prepared from sodium alginate (SA) and metal chlorides and characterized with XRD and FT-IR spectrometry, was used for the preparation of biodiesel via esterification reaction. The study results showed that the aluminum-alginate complex prepared in a cheap and easy way exhibited high catalytic activity, and a 92.6% conversion of methyl oleate was obtained in the presence of 4m% of catalyst dosage upon refluxing for 3h of methanol and acid mixed in a molar ratio of 10:1. It should be noted that the catalyst can be applied to the esterification reaction of fatty acids with various carbon chain length on methanol or different short chain alcohols, indicating that the catalyst is suitable for the preparation of biodiesel from waste oils with a high acid value.

Intranasal Immunization Using CTA1-DD as a Mucosal Adjuvant for an Inactivated Influenza Vaccine

Objective To evaluate the effect of intranasal immunization with CTA1-DD as mucosal adjuvant combined with H3N2 split vaccine. Methods Mice were immunized intranasally with PBS(negative control), or H3N2 split vaccine(3 μg/mouse) alone, or CTA1-DD(5 μg/mouse) alone, or H3N2 split vaccine(3 μg/mouse) plus CTA1-DD(5 μg/mouse). Positive control mice were immunized intramuscularly with H3N2 split vaccine(3 μg/mouse) and alum adjuvant. All the mice were immunized twice, two weeks apart. Then sera and mucosal lavages were collected. The specific HI titers, IgM, IgG, IgA, and IgG subtypes were examined by ELISA. IFN-γ and IL-4 were test by ELISpot. In addition, two weeks after the last immunization, surivival after H3N2 virus lethal challenge was measured. Results H3N2 split vaccine formulated with CTA1-DD could elicit higher Ig M, Ig G and hemagglutination inhibition titers in sera. Furthermore, using CTA1-DD as adjuvant significantly improved mucosal secretory Ig A titers in bronchoalveolar lavages and vaginal lavages. Meanwhile this mucosal adjuvant could enhance Th-1-type responses and induce protective hemagglutination inhibition titers. Notably, the addition of CTA1-DD to split vaccine provided 100% protection against lethal infection by the H3N2 virus. Conclusion CTA1-DD could promote mucosal, humoral and cell-mediated immune responses, which supports the further development of CTA1-DD as a mucosal adjuvant for mucosal vaccines.

A study of bile kinetics and flow pattern of human gallbladder in vivo

Based on the principle of fluid mechanics a mathematical model of the oval gallbladder’smoving boundaries was obtained by CT,radio contrast radiography and B mode echography.Weadopted for the first time in this field,the finite element method to calculate the transient flow fieldwithin the human gallbladder in vivo and successfully made out the distribution of bile flow withinthe cyst,known as Newtonian fluid and axisymmetric flow.Thus we completed the poineering ofthe bile flow study within the gallbladder,and confirmed the way of the cholelithogenesis withinthe cyst.Theoretically the vortex flow is proved to be the mechanical factor in the formation ofgallbladder stone and several conclusions were drawn from this study:(1)near the axis of thecontacting gallbladder exists an accelerated bile out-flow column;(2)near the central cross-section ofthe flow field there exist two opposed vortex areas,the one which near the axis rotatescounterwise and flows faster;(3)a gross similarity exists between the law of attenuation of bile flowvelocity and the gallbladder contraction;(4)chololithogenesis within the cyst is related to the vortex inthe flow field.

Microfabrication,surface modification,and laser guidance techniques to create a neuron biochip

In this report we illustrate our application of soft lithography-based microfabrication,surface modification,and our unique laser cell-patterning system toward the creation of neuron biochips. We deposited individual forebrain neurons from Day 7 embryonic chicks into two rows of eight in a silicon microstructure aligned over a microelectrode array (MEA). The polydimethylsiloxane (PDMS) membrane with microstructures to confine cells and guide network connectivity was aligned to the electrodes of a MEA. Both the MEA and the PDMS membrane were treated with O2 plasma,Poly-L-Lysine,and Laminin to aid in cell attachment and survival. The primary advantage of our process is that it is quicker and simpler than previous cell-placement methods and may make highly defined neuronal network biochips more practical.

Expression, purification and characterization of a phyA^m-phyCs fusion phytase

The phyA^m gene encoding acid phytase and optimized neutral phytase phyCs gene were inserted into expression vector pPIC9K in correct orientation and transformed into Pichiapastoris in order to expand the pH profile ofphytase and decrease the cost of production. The fusion phytase phyA^m-phyCs gene was successfully overexpressed in P. pastoris as an active and extracellular phytase. The yield of total extracellular fusion phytase activity is （25.4±0.53） U/ml at the flask scale and （159.1±2.92） U/ml for high cell-density fermentation, respectively. Purified fusion phytase exhibits an optimal temperature at 55 ℃ and an optimal pH at 5.5-6.0 and its relative activity remains at a relatively high level of above 70% in the range ofpH 2.0 to 7.0. About 51% to 63% of its original activity remains after incubation at 75 ℃ to 95 ℃ for 10 min. Due to heavy glycosylation, the expressed fusion phytase shows a broad and diffuse band in SDS-PAGE （sodium dodecyl sulfate-polyacrylamide gel electrophoresis）. After deglycosylation by endoglycosidase H （EndoHf）, the enzyme has an apparent molecular size of 95 kDa. The characterization of the fusion phytase was compared with those ofphyCs andphyA^m.

Cost effective filamentous phage based immunization nanoparticles displaying a full-length hepatitis B virus surface antigen

Hepatitis B virus (HBV) is one of the major causes of chronic hepatitis, cirrhosis and liver cancer. In combating HBV infections, HBV diagnosis and vaccination are therefore critical. The hepatitis B virus surface antigen (HBsAg) is a key target molecule in developing vaccines and diagnostic systems. To date, although HBsAg has been expressed in bacteria, yeasts and mammalian cells, there are still limitations in the existing ones, which leave the necessity for searching new HBsAg production methods. In this study, a simple phage display-based method was developed to produce the purified full-length HBsAg molecules for further immunization studies. For this purpose, the HBsAg coding gene was cloned into a pCANTAB5E phagemid vector and expressed on the surface of M13 filamentous phages. The HBsAg-expressing phage nanosystem was then used as immunization agent in BALB/cJ mice. The ELISA results for sera obtained from mice immunized with HBsAg-displaying phage particles revealed an immune response against HBsAg. These results demonstrate the potential use of a full-length antigen to be displayed on phages as cost effective adjuvant-free immunization agents as an alternative to the highly purified and more expensive antigens conjugated with carrier molecules.

Changes in protein N-glycosylation during the fruit development and ripening in melting-type peach

The posttranslational modification of proteins with complex carbohydrate moieties(glycosylation)regulates the process of fruit ripening.Exoglycosidases are enzymes that can trim this protein glycosylation and are therefore considered to be important targets in the control of fruit ripening and softening.Melting-type peaches are popular seasonal fruits in many Asian regions,but the extremely short shelf-life of the peach fruits significantly hampers their economic value.To investigate the effect of the protein glycosylation and exoglycosidase activities on the development and ripening of the peach fruit,the fruit flesh of the melting peach cultivar'Xia hui 6'at five different maturity stages were analyzed.The N-glycan profile of each sample was characterized and quantified by HILIC-UPLC and MALDI-TOF mass spectrometry,revealing two characteristic N-glycan structures(MMXF and GnGnMXF)which were strongly affected by the state of maturity.Furthermore,it was shown that one of the endogenous exoglycosidase activities analyzed(β-N-acetylhexosaminidase,β-Hex)correlated with the MMXF and GnGnMXF N-glycan structures(p<0.05)in an obverse manner.These findings lay the foundation for further elucidation of the physiological functions of protein glycosylation in peach fruit development and ripening.

Novel chemical-and protein-mediated methods for glucosamine detection

We describe two novel approaches for the determination of glucosamine(GlcN).The first approach is based on the chemical derivatization of GlcN with the non-fluorophor 1,3-diphenyl-1,3-propanedione(DPPD),which results in a condensation product with interesting fluorescent properties.The obtained compound was isolated by silica-gel chromatography and its structure elucidated by NMR and mass spectrometry.The second approach is based on a previously undescribed sensitivity of the enzyme glucosamine-6-phosphate deaminase(GPDA)towards GlcN,which resulted in the precipitation of the enzyme.Using a rational enzyme engineering approach and both liquid-based and plate-based screening methods,mutational GPDA variants with significantly improved precipitation properties were identified and characterized.These novel glucosamine detection methods may be a useful addition to the repertoire of currently available glucosamine detection sensors.

腰椎术后邻近节段退变及再手术

腰椎邻近节段退变是指腰椎手术后手术节段头端或尾端发生的退行性改变，其中一部分患者同时出现相应的临床症状，称之为邻近节段疾病。近年来虽然有非常多的新技术涌现，但邻近节段退变并未真正得到解决。通过对MEDLINE／PubMed、Cochrane Controlled Trials Registry、EMBASE数据库进行检索，纳入所有使用融合和（或）固定、单纯减压或人工腰椎间盘置换三种手术治疗腰椎退行性疾病的随机或非随机临床研究，同时保证纳入研究的病例数量〉t20例及患者年龄≥18岁。排除个案报道、综述或荟萃分析、无法获得摘要的文献，以及创伤、感染、肿瘤和炎症性疾病的研究。主要针对邻近节段退变的定义及诊断标准，以及邻近节段退变及再手术的发生率和危险因素进行综述。文献中邻近节段退变的概念在使用上较为混乱，影像学上退变同症状性退变常常混杂使用，因此对文献间进行横向比较得出结论较为困难。此外，既往研究并未全面了解邻近节段退变的发病机制及危险因素，特别是手术节段对邻近节段的影响。且目前文献报道的结果多为回顾性研究所得，尚缺乏高等级证据。腰椎融合术后再手术的主要原因是邻近节段退变，降低再手术率最主要的方法就是降低邻近节段退变的发生率。应首先统一邻近节段退变的诊断标准，同时对包括手术节段在内的各种囡素进行全面研究，通过高等级证据阐明邻近节段退变的发生机制和危险因素。

Cervical spinal canal narrowing and cervical neurological injuries

Cervical spinal canal narrowing can lead to injury of the spinal cord and neurological symptoms including neck pain,headache,weakness and parasthesisas.According to previous and recent clinical researches,we investigated the geometric parameters of normal cervical spinal canal including the sagittal and transverse diameters as well as Torg ratio.The mean sagittal diameter of cervical spinal canal at C1 to C7 ranges from 15.33 mm to 20.46 mm,the mean transverse diameter at the same levels ranges from 24.45 mm to 27.00 mm and the mean value of Torg ratio is 0.96.With respect to narrow cervical spinal canal,the following charaterstics are found：firstly,extension of the cervical spine results in statistically significant stenosis as compared with the flexed or neutral positions; secondly,females sustain cervical spinal canal narrowing more easily than males;finally,the consistent narrowest cervical canal level is at C4 for all ethnicity,but there is a slight variation in the sagittal diameter of cervical spinal stenosis（≤ 14 mm in Whites,≤12 mm in Japanese,≤ 13.7 mm in Chinese）.Narrow sagittal cervical canal diameter brings about an increased risk of neurological injuries in traumatic,degenerative and inflammatory conditions and is related with extension of cervical spine,gender,as well as ethnicity.It is hoped that this review will be helpful in diagnosing spinal cord and neurological injuries with the geometric parameters of cervical spine in the future.

Biomechanics of whiplash injury

Despite a large number of rear-end collisions on the road and a high frequency of whiplash injuries reported, the mechanism of whiplash injuries is not completely understood. One of the reasons is that the injury is not necessarily accompanied by obvious tissue damage detectable by X-ray or MRI. An extensive series of biomechanics studies, including injury epidemiology, neck kinematics,facet capsule ligament mechanics, injury mechanisms and injury criteria, were undertaken to help elucidate these whiplash injury mechanisms and gain a better understanding of cervical facet pain. These studies provide the following evidences to help explain the mechanisms of the whiplash injury: (1) Whiplash injuries are generally considered to be a soft tissue injury of the neck with symptoms such as neck pain and stiffness, shoulder weakness, dizziness, headache and memory loss, etc. (2) Based on kinematical studies on the cadaver and volunteers, there are three distinct periods that have the potential to cause injury to the neck. In the first stage, flexural deformation of the neck is observed along with a loss of cervical lordosis; in the second stage, the cervical spine assumes an S-shaped curve as the lower vertebrae begin to extend and gradually cause the upper vertebrae to extend; during the final stage, the entire neck is extended due to the extension moments at both ends. (3)The in vivo environment afforded by rodent models of injury offers particular utility for linking mechanics, nociception and behavioral outcomes. Experimental findings have examined strains across the facet joint as a mechanism of whiplash injury, and suggested a capsular strain threshold or a vertebral distraction threshold for whiplash-related injury,potentially producing neck pain. (4) Injuries to the facet capsule region of the neck are a major source of post-crash pain. There are several hypotheses on how whiplash-associated injury may occur and three of these injuries are related to strains within the facet capsule connected with events early in the impact. (5) There are several possible injury criteria to correlate with the duration of symptoms during reconstructions of actual crashes. These results form the biomechanical basis for a hypothesis that the facet joint capsule is a source of neck pain and that the pain may arise from large strains in the joint capsule that will cause pain receptors to fire.

In vivo ranges of motion of cervical segments in patients with cervical spondylosis during dynamic neck motions

Cervical spondylosis refers to degenerative changes in the sub-axial cervical spine.Symptoms caused by spondylosis include axial neck pain,cervical radiculopathy,and cervical myelopathy.One of the most commonly used surgical treatments is anterior cervical discectomy and fusion(ACDF);it is reported that ACDF leads to the development of progressive adjacent segment degeneration(ASD)in over 90%of the patients with up to 25.6%requiring reoperations due to symptomatic ASD.

Construction of precise support vector machine based models for predicting promoter strength

Background： The prediction of the prokaryotic promoter strength based on its sequence is of great importance not only in the fundamental research of life sciences but also in the appfied aspect of synthetic biology. Much advance has been made to build quantitative models for strength prediction, especially the introduction of machine learning methods such as artificial neural network （ANN） has significantly improve the prediction accuracy. As one of the most important machine learning methods, support vector machine （SVM） is more powerful to learn knowledge from small sample dataset and thus supposed to work in this problem. Methods： To confirm this, we constructed SVM based models to quantitatively predict the promoter strength. A library of 100 promoter sequences and strength values was randomly divided into two datasets, including a training set （≥10 sequences） for model training and a test set （≥ 10 sequences） for model test. Results： The results indicate that the prediction performance increases with an increase of the size of training set, and the best performance was achieved at the size of 90 sequences. After optimization of the model parameters, a high-performance model was finally trained, with a high squared correlation coefficient for fitting the training set （R^2〉 0.99） and the test set （R^2〉 0.98）, both of which are better than that of ANN obtained by our previous work. Conclusions： Our results demonstrate the SVM-based models can be employed for the quantitative prediction of promoter strength.

Development of a new biomechanical indicator for primary blast-induced brain injury

Primary blast-induced traumatic brain injury （bTBI） has been observed at the boundary of brain tissue and cerebrospinal fluid （CSF）. Such injury can hardly be explained by using the theory of compressive wave propagation, since both the solid and fluid materials have similar compressibility and thus the intracranial pressure （ICP） has a continuous distribution across the boundary. Since they have completely different shear properties, it is hypothesized the injury at the interface is caused by shear wave. In the present study, a preliminary combined numerical and theoretical analysis was conducted based on the theory of shear wave propagation]reflection. Simulation results show that higher lateral acceleration of brain tissue particles is concentrated in the boundary region. Based on this finding, a new biomechanical vector, termed as strain gradient, was suggested for primary bTBI. The subsequent simple theoretical analysis reveals that this parameter is proportional to the value of lateral acceleration. At the boundary of lateral ventricles, high spatial strain gradient implies that the brain tissue in this area （where neuron cells may be contained） undergo significantly different strains and large velocity discontinuity, which may result in mechanical damage of the neuron cells.

Synbiological systems for complex natural products biosynthesis

Natural products(NPs)continue to play a pivotal role in drug discovery programs.The rapid development of synthetic biology has conferred the strategies of NPs production.Synthetic biology is a new engineering discipline that aims to produce desirable products by rationally programming the biological parts and manipulating the pathways.However,there is still a challenge for integrating a heterologous pathway in chassis cells for overproduction purpose due to the limited characterized parts,modules incompatibility,and cell tolerance towards product.Enormous endeavors have been taken for mentioned issues.Herein,in this review,the progresses in naturally discovering novel biological parts and rational design of synthetic biological parts are reviewed,combining with the advanced assembly technologies,pathway engineering,and pathway optimization in global network guidance.The future perspectives are also presented.