Pathogenesis of Terson syndrome

Purpose:The aim of this experimental study was to investigate the pathogenesis of Terson syndrome (TS), which currently is controversial.Methods:The central retinal artery (in 39 orbits), posterior ciliary arteries (in 8 orbits), and central retinal vein (CRV in 21 orbits) were occluded in rhesus monkeys by exposing them to lateral orbitotomy. Fundus examination and fluorescein fundus angiography were performed before and immediately after cutting the vessels and serially thereafter during the follow-up period. The rationale of the experimental study design is discussed.Results:In eyes with central retinal artery occlusion, retinal hemorrhages were seen soon after the procedure in 7 eyes, and on follow-up in a total of 15 eyes. In posterior ciliary artery occlusion, retinal hemorrhages were seen soon after the procedure in one eye, and on follow-up in a total of three eyes. In eyes with CRV, all eyes had extensive scattered retinal hemorrhages.Conclusion:The findings of this experimental study, and my basic, experimental, and comprehensive clinical studies on CRVO, suggest the following concept of the pathogenesis of TS: Compression of the CRV plays a crucial role in the development of TS. The CRV is compressed, as it lies in the subarachnoid space of the optic nerve sheath, by raised cerebrospinal fluid pressure and/or accumulated blood. This results in retinal venous stasis and raised venous pressure in the retinal veins, leading to venous engorgement, rupture of the retinal capillaries and retinal hemorrhages. The clinical importance of compression of the CRV and not occlusion of CRV in TS is that optic nerve sheath decompression by opening it and releasing the blood and raised cerebrospinal fluid (CSF) pressure, would result in immediate decompressing of the CRV in the subarachnoid space and restoration of normal circulation and prevent visual loss.     

Mesoscale Analysis of the Effect of Interfacial Transition Zone on the Compressive Damage of Concrete Based on Discrete Element Method

The coarse aggregate–mortar interface transition zone (ITZ) has a great influence on the mechanical properties of concrete, which cannot be easily studied using laboratory tests in the mesoscale. In this paper, a series of axial compression tests were conducted using the discrete element method (DEM) on concrete specimens for four phases: coarse aggregates, mortars, aggregate–mortar interface transition zones, and voids. The effects of ITZ strength on macroscopic stress and microscopic cracks under different strength reduction factors were investigated through axial compression testing. With the increase in interface transition strength, the compressive strength of the concrete becomes stronger; moreover, the number of cracks decreases, and the anisotropy of contact orientation becomes weaker. Meanwhile, the direction of crack development and the damage mode of compressed concrete specimens were also dependent on the coarse aggregate–mortar interface strength coefficient.     

Effect of Stitching,Stitch Density,Stacking Sequences on Low-Velocity Edge Impact and Compression after Edge Impact (CAEI) Behavior of Stitched CFRP Laminates

Low-velocity edge impact and compression after edge impact (CAEI) behavior of stitched carbon-fiber-reinforced plastic (CFRP) laminates were experimentally investigated in the paper. Five groups, including three stacking sequences (P₁, P₂, P₃) and two stitch densities (stitch space × stitch pitch is 10 mm × 10 mm and 15 mm × 15 mm) of stitched/unstitched CFRP laminates, were prepared by the VARTM technique and subjected to low-velocity edge impact and compression after edge impact experiments. The damage of CFRP laminates was detected by optical observation and micro-CT. The effects of stitching, stitch density, stacking sequences and impact energy on properties of edge impact and CAEI were discussed. The results show that the damage of edge impact of stitched laminates is smaller than that of unstitched laminates. The main failure mode of CAEI of the unstitched laminates is delamination and that of the stitched laminates is global buckling. The addition of stitches can effectively improve the edge impact resistance and damage tolerance of CFRP laminates. Compared with the unstitched laminates with the same stacking sequence, the peak impact force of the laminates with stitch density 15 mm × 15 mm increases by 5.61–12.43%, and the increase in residual compression strength is up to 5–20.9%. The peak impact force of the laminates with stitch density 10 mm × 10 mm increases by 8.1–31.4%, and the increase in residual compression strength is up to 24.2–27%. Compared with the other two stacking sequences (P₁ and P₂), the stacking sequence P₃ has excellent resistance of edge impact and CAEI properties.     

Magnetic Resonance Imaging Findings in Patients with Tarsal Tunnel Syndrome

Tarsal tunnel syndrome (TTS) is a common entrapment syndrome whose diagnosis can be difficult. We compared preoperative magnetic resonance imaging (MRI) and operative findings in 23 consecutive TTS patients (28 sides) whose mean age was 74.5 years. The 1.5T MRI sequence was 3D T2* fat suppression. We compared the MRI findings with surgical records and intraoperative videos to evaluate them. MRI- and surgical findings revealed that a ganglion was involved on one side (3.6%), and the other 27 sides were diagnosed with idiopathic TTS. MRI visualized the nerve compression point on 23 sides (82.1%) but failed to reveal details required for surgical planning. During surgery of the other five sides (17.9%), three involved varices, and on one side each, there was connective tissue entrapment or nerve compression due to small vascular branch strangulation. MRI studies were useful for nerve compression due to a mass lesion or idiopathic factors. Although MRI revealed the compression site, it failed to identify the specific involvement of varices and small vessel branches and the presence of connective tissue entrapment.     

良性肝脏肿瘤肝移植相关进展

肝脏肿瘤分为良性和恶性,其中良性肝脏肿瘤较为常见,治疗以随访观察、介入治疗为主,仅少数情况下需要进行外科手术切除治疗。肝移植可有效治疗终末期肝病,但通常不作为良性肝脏肿瘤的治疗手段,仅存在巨大占位压迫、合并肝衰竭、肿瘤破裂出血风险或恶变风险的良性肝脏肿瘤才考虑进行肝移植治疗。与恶性肿瘤及慢性肝衰竭肝移植相比,良性肝脏肿瘤肝移植手术风险相当,预后及远期生存较为理想。但良性肝脏肿瘤肝移植术前应充分谨慎评估,同时注意新形势下供肝匹配难度。本文对良性肝脏肿瘤包括肝血管瘤、多囊肝、肝细胞腺瘤、肝脏间叶错构瘤等肝移植相关研究进展进行总结,旨在为肝移植治疗良性肝脏肿瘤提供参考。     

Active Food Packaging Made of Biopolymer-Based Composites

Food packaging plays a vital role in protecting food products from environmental damage and preventing contamination from microorganisms. Conventional food packaging made of plastics produced from unrenewable fossil resources is hard to degrade and poses a negative impact on environmental sustainability. Natural biopolymers are attracting interest for reducing environmental problems to achieve a sustainable society, because of their abundance, biocompatibility, biodegradability, chemical stability, and non-toxicity. Active packaging systems composed of these biopolymers and biopolymer-based composites go beyond simply acting as a barrier to maintain food quality. This review provides a comprehensive overview of natural biopolymer materials used as matrices for food packaging. The antioxidant, water barrier, and oxygen barrier properties of these composites are compared and discussed. Furthermore, biopolymer-based composites integrated with antimicrobial agents—such as inorganic nanostructures and natural products—are reviewed, and the related mechanisms are discussed in terms of antimicrobial function. In summary, composites used for active food packaging systems can inhibit microbial growth and maintain food quality.     

Thermomechanical Fatigue Testing on Fe-Mn-Si Shape Memory Alloys in Prestress Conditions

Active materials have gained increasing momentum during the last decades due to their ability to act as sensors and actuators without the need for an external controlling system or an electronic signal. Shape memory alloys (SMAs), which are a subcategory of active materials, are slowly being introduced in the civil engineering sector in applications that refer to prestressing and strengthening of various structural elements. Low-cost iron-based SMAs are a good alternative to the Ni-Ti SMAs for such uses since the cost of large-scale civil engineering applications would otherwise be prohibitive. The scope of this study is the investigation of the thermomechanical response of the Fe-17Mn-5Si-10Cr-4Ni-1(V,C) ferrous SMA. In particular, this study focuses on the application of prestress, and on the alloy’s behavior under fatigue loadings. In addition, the effect of loading frequency on the recovery stress of the material is thoroughly investigated. Four dog-bone specimens were prepared and tested in low-cycle fatigue. All the experiments aimed at the simulation of prestress. The recovery stress was monitored after pre-straining and heating applied under strain–control conditions. The experimental results are promising in terms of the is situ prestress feasibility since the measured recovery stress values are satisfactory high.     

Influence of Processing Parameters on the Mechanical Properties of Peek Plates by Hot Compression Molding

Thermoplastic components are gaining more and more attention due to their advantages which include high specific strength, high toughness, and low manufacturing costs. Despite the fast development of such materials in engineering applications, the major challenge for the wider use of thermoplastic components is the diverse mechanical properties that are caused by uncertain factors during the molding process. In this paper, the effects of processing parameters on the mechanical properties of PEEK plates by hot compression molding are systematically investigated, including the temperature, pressure, and compression time. It was found that both temperature and time can sensitively change the mechanical properties; however, a pressure larger than 1.5 MPa showed a limited impact on the mechanical behaviors of PEEK plates. The optimal process parameters include a hot compression temperature of 400 °C, a compression time of 30 min, and a pressure of 2.5 MPa.     

急性儿童系统性EB病毒阳性T细胞淋巴组织增殖性疾病临床病理观察

目的：探讨急性儿童系统性EB病毒阳性T细胞淋巴组织增殖性疾病的发病机制、临床病理特征及鉴别诊断要点,以缩短诊断时间和减少误诊。方法：结合文献分析1例急性儿童系统性EB病毒阳性T细胞淋巴组织增殖性疾病死亡病例的临床症状和体征、病理特征及免疫组织化学、EBER原位杂交、基因克隆重排结果等。结果：急性儿童系统性EB病毒阳性T细胞淋巴组织增殖性疾病临床上主要表现为嗜血综合征,包括发热、淋巴结及肝脾肿大、外周血三系减少,可伴有腹水及胸腔积液,血清EB病毒载量增高、血清铁蛋白明显增高,肝肾功能、凝血、血脂等均异常;骨髓涂片示异型淋巴细胞约占18%,并可见嗜血现象。淋巴结活检示其结构破坏,淋巴滤泡减少,T区明显扩大,可见轻-中度异型淋巴细胞;淋巴窦扩张,组织细胞增生,可见嗜血现象,间质血管增生。免疫组化证实EB病毒感染的细胞毒性T细胞构成病变主体;EBER原位杂交部分淋巴细胞胞核阳性;淋巴结组织标本基因重排示TCR基因发生克隆性重排,患者在发病第27天因多脏器衰竭死亡。结论：急性儿童系统性EB病毒阳性T细胞淋巴组织增殖性疾病是一种系统性病变,部分患者病情急剧恶化死于严重并发症。该病病情多较复杂,且与其它疾病存在重叠或交叉,早期确诊困难,目前证实其中T淋巴细胞增生为克隆性增生,为T细胞淋巴瘤。应提高对其病理认识,并紧密结合临床、检验、免疫表型、基因重排等因素,减少治疗延误。