Safety evaluation of a new setup for transcranial electric stimulation during magnetic resonance imaging

BackgroundTranscranial electric stimulation during MR imaging can introduce safety issues due to coupling of the RF field with the stimulation electrodes and leads.ObjectiveTo optimize the stimulation setup for MR current density imaging (MRCDI) and increase maximum stimulation current, a new low-conductivity (σ = 29.4 S/m) lead wire is designed and tested.MethodThe antenna effect was simulated to investigate the effect of lead conductivity. Subsequently, specific absorption rate (SAR) simulations for realistic lead configurations with low-conductivity leads and two electrode types were performed at 128 MHz and 298 MHz being the Larmor frequencies of protons at 3T and 7T. Temperature measurements were performed during MRI using high power deposition sequences to ensure that the electrodes comply with MRI temperature regulations.ResultsThe antenna effect was found for copper leads at ¼ RF wavelength and could be reliably eliminated using low-conductivity leads. Realistic lead configurations increased the head SAR and the local head SAR at the electrodes only minimally. The highest temperatures were measured on the rings of center-surround electrodes, while circular electrodes showed little heating. No temperature increase above the safety limit of 39 °C was observed.ConclusionCoupling to the RF field can be reliably prevented by low-conductivity leads, enabling cable paths optimal for MRCDI. Compared to commercial copper leads with safety resistors, the low-conductivity leads had lower total impedance, enabling the application of higher currents without changing stimulator design. Attention must be paid to electrode pads.     

Carbazole‐Substituted Triphenylamine and Diketopyrrolopyrrole Alternating Copolymer for Photovoltaic Cells

A new alternating conjugated polymer (PTCDPP) of carbazole‐substituted triarylamine and diketopyrrolopyrrole is prepared and characterized in detail. The polymer exhibits two strong absorption bands at 345 and 600 nm. With highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of ?5.13 eV and ?3.67 eV, PTCDPP displays an energy gap of 1.66 eV. PTCDPP‐based bulk heterojunction solar cells with a structure of fluorinated tin oxide (FTO)/TiO₂/PTCDPP:[6,6]‐phenyl‐C61‐butyric acid methyl ester (PCBM)/MoO₃/Ag are fabricated. The devices are optimized by adjusting the composition of the PTCDPP:PCBM active layer, thermal treatment, and addition of processing additives. The device based on PTCDPP:PCBM (1:4, w/w) shows a power conversion efficiency (PCE) of 2.31%, with a short‐circuit current of 4.17 mA cm^?2, an open‐circuit voltage of 0.79 V, and a fill factor of 0.35. The best cell performance (2.65% PCE) is achieved by using 1,8‐diiodooctane (3%, v/v) as a processing additive and annealing the active layer at 80 °C.

     

创伤性血胸和气胸患者胸腔引流管径大小选择与预后的相关性

目的探讨胸腔引流管径的大小对患者预后的影响。方法回顾性分析2010年1月至2019年12月航天中心医院收治因胸部创伤而进行胸腔引流管置入的74例患者资料,评估患者特征与引流管的大小、额外置管的风险和并发症的相关性。结果74例患者置入胸管86根,77根引流管作为初始引流管(3例患者需要双侧引流),9根为额外放置的引流管(置管原因分别为残余气胸3例,残余血胸4例,残余血气胸1例,胸腔外放置不当1例),附加引流管的管径与初始引流管相比较,差异无显著性(P=0.19,95%CI:-1.62~4.95)。初始置管放置的大小与患者的性别、指征、呼吸状态(有无气管插管)、受伤机制无相关性;引流管的大小与患者的年龄、体重指数、修订后的创伤评分、损伤严重程度评分、适应证、胸部损伤简短量表评分无相关性。按引流管大小将患者分为≥14 Fr组和<14 Fr组,两组间需要额外插管、血肿/气胸残留、胸膜外放置不当的风险差异无显著性,不需要额外的导管或手术干预治疗导管阻塞或残留的血胸凝块。结论在胸部外伤患者中放置<14 Fr引流管,残余血肿/气胸和阻塞引流的风险并未增加,引流充分有效。     

Toll样受体4在慢性牙周炎诱发大鼠肝脏炎症中的作用

目的:初步探究Toll样受体4(Toll like receptor 4,TLR4)在慢性牙周炎诱发大鼠肝脏炎症中的作用。方法:将24只雄性Wistar大鼠随机分成两组,对照组和牙周炎组每组各12只,2%戊巴比妥钠麻醉下检测牙龈出血指数、牙周探诊深度及松动度;将20μL牙龈卟啉单胞菌脂多糖(Porphyromonas gingivalis lipopolysaccharide,Pg-LPS)(1 g/L)注射到大鼠双侧上颌第一磨牙龈沟及第一二磨牙龈间隙内,隔1 d注射1次,每周3次,连续6周。对照组不做处理。最后一次注射Pg-LPS 12 h后,2%戊巴比妥钠麻醉下检测牙周探诊深度、牙龈出血指数及松动度等3项牙周指标后将大鼠处死,取其上颌骨及肝脏,采用组织学方法、实时荧光定量聚合酶链反应(quantitative real-time polymerase chain reaction,qRT-PCR)、Western blot分别检测肝组织炎症反应情况及TLR4、肿瘤坏死因子-α(tumor necrosis factor,TNF-α)和白细胞介素-6(interleukin-6,IL-6)的基因和蛋白表达水平。结果:牙周炎组大鼠牙周探诊深度、牙龈出血指数及松动度均重于对照组;苏木精-伊红(hematoxylin-eosin,HE)染色结果显示慢性牙周炎大鼠肝组织内肝索结构紊乱,汇管区可见大量淋巴细胞浸润,大量肝细胞呈空泡样改变;qRT-PCR结果显示慢性牙周炎组大鼠肝组织TLR4、TNF-α和IL-6的mRNA表达水平较对照组升高;Western blot结果显示TLR4蛋白表达与基因表达一致。结论:TLR4在慢性牙周炎诱发大鼠肝脏炎症性改变的过程中发挥着重要的作用。     

Relationship between different types of helicobacter pylori infection and metabolic syndrome in healthy people

Objective To explore the relationship between different types of helicobacter pylori (Hp) infection and metabolic Syndrome (MS) in healthy population. Methods The data of 4 602 adults who underwent physical examination in the Space Center Hospital from January to December 2019 were collected for research, the serum Hp antibody typing was detected by immunoblotting, and the results of liver ultrasound and blood biochemical examination were collected for statistical analysis. Results Among the physical examination population,there were 2 018 cases with positive serum Hp antibody and 2 584 cases with negative serum Hp antibody.According to the expression of cytotoxin-associated gene A protein (CagA) and vacuolar toxin, 2 018 patients with positive serum Hp antibody were divided into 1 088 cases in type Ⅰ group (53.9%(1 088/2 018)) and 930 cases in type Ⅱ Group (46.1%(930/2 018)). There were significant differences in age, systolic blood pressure and prevalence of nonalcoholic fatty liver disease (NAFLD) between type Ⅰ group and type Ⅱ Group (P<0.05). There was no significant difference in gender, fasting blood glucose, triglyceride, high-density lipoprotein cholesterol (HDL-C), diastolic blood pressure, body mass index (BMI) and waist circumference between the two groups (P>0.05). There was no significant difference in the prevalence of ms between the two groups (18.3% (199/1 088)) and 19.0% (177/930), P=0.670). Multivariate logistic regression analysis showed that there was no correlation. between different serum Hp antibody typing and MS (OR=1.194, 95% CI 0.842-1.693, P=0.319). Conclusion Different subtypes of type Ⅰ and type Ⅱ Hp infection are not distinctly associated with metabolic syndrome. © 2021, Chinese Medical Journals Publishing House Co.Ltd. All rights reserved.     

Different effects of soil bacterial communities affected by biocontrol agent YH-07 on tomato Fusarium wilt inhibition

Bio-organic fertilizers based on biocontrol microorganisms have been widely applied to suppress soilborne diseases and improve crop yields. Studies on beneficial biocontrol agents have promoted the development of the bio-organic fertilizers in China. Our previous study demonstrated that a biocontrol agent, Erythrobacter sp. YH-07, can inhibit the growth of the plant pathogen Fusarium oxysporum. In the present study, we investigated the effects of this biocontrol agent on tomato wilt and used the illumina-based sequencing approach to characterize the variations in soil bacterial communities in a potted experiment. The aim of our study was to explore the potential correlation among bacterial communities, Fusarium wilt suppression, and soil properties after application of the biocontrol agent YH-07. The results showed that application of Erythrobacter sp. YH-07 effectively controlled outbreaks of tomato Fusarium wilt. The illumina MiSeq sequencing showed that Proteobacteria was the predominant phylum in the soil samples. Bacterial community composition and structure varied under different soil treatments, e.g., the relative abundance of Erythrobacter and Salinimicrobium was significantly increased in the YH treatment, and Acidobacteria were decreased in the YH treatment compared with the CK treatment. Additionally, the correlation results showed that the soil organic matter and available phosphorus and potassium were higher after YH-07 application, and they were positively correlated with bacterial community. The redundancy analysis showed Erythrobacter and Acidobacteria were the dominant genera after YH and CK treatments, respectively, and correlations with tomato Fusarium wilt incidence were negative and positive, respectively.

The model plant tomato was used to verify the effect and mechanism of a novel discovered strain YH-07 which is a potential agent for biological control of soil borne disease named tomato Fusarium wilt.     

Phytoplankton diversity and community responses to physicochemical variables in mangrove zones of Guangzhou Province,China

Ecotoxicology - The phytoplankton diversity and community response to physicochemical variables in mangrove zones of Guangdong Province along the South China coast was investigated from October to...     

Dissecting the hypothalamic pathways that underlie innate behaviors

Many complex behaviors that do not require learning are displayed and are termed innate. Although traditionally the subject matter of ethology,innate behaviors offer a unique entry point for neuroscientists to dissect the physiological mechanisms governing complex behaviors. Since the last century,converging evidence has implicated the hypothalamus as the central brain area that controls innate behaviors. Recent studies using cutting-edge tools have revealed that genetically-defined populations of neurons residing in distinct hypothalamic nuclei and their associated neural pathways regulate the initiation and maintenance of diverse behaviors including feeding,sleep,aggression,and parental care. Here,we review the newly-defi ned hypothalamic pathways that regulate each innate behavior. In addition,emerging general principles of the neural control of complex behaviors are discussed.