Association between acute pancreatitis and small intestinal bacterial overgrowth assessed by hydrogen breath test

AIM To elucidate the effects of small intestinal bacterial overgrowth(SIBO) on the severity and complications of acute pancreatitis(AP).METHODS In total,208 patients with AP as defined by the revised Atlanta classification were admitted to Xuanwu Hospital of capital Medical University from 2013 to 2016. All patients were admitted within 72 h of AP onset. The hydrogen breath test was performed 7 d after AP onset to detect hydrogen production and evaluate the development of SIBO. The incidence of SIBO was analyzed in patients with AP of three different severity grades. The association between SIBO and complications of AP was also assessed.RESULTS Of the 27 patients with severe AP(SAP),seven(25.92%) developed SIBO. Of the 86 patients with moderately severe AP(MSAP),22(25.58%) developed SIBO. Of the 95 patients with mild AP(MAP),eight(8.42%) developed SIBO. There were significant differences in the rates of SIBO among patients with AP of different severities. Additionally,more severe APwas associated with higher rates of SIBO positivity(P < 0.05). SIBO in patients with AP mainly occurred within 72 h of the onset of AP. The incidence of organ failure was significantly higher in patients with SIBO than in those without(P < 0.05).CONCLUSION SIBO occurs more frequently in patients with MSAP or SAP than in those with MAP,usually ≤ 72 h after AP onset. Additionally,SIBO is associated with organ failure.

Four-sample lactose hydrogen breath test for diagnosis of lactose malabsorption in irritable bowel syndrome patients with diarrhea

AIM: To validate 4-sample lactose hydrogen breath testing(4SLHBT) compared to standard 13-sample LHBT in the clinical setting.METHODS: Irritable bowel syndrome patients with diarrhea(IBS-D) and healthy volunteers(HVs) were enrolled and received a 10 g, 20 g, or 40 g doselactose hydrogen breath test(LHBT) in a randomized, double-blinded, controlled trial. The lactase gene promoter region was sequenced. Breath samples and symptoms were acquired at baseline and every 15 min for 3 h(13 measurements). The detection rates of lactose malabsorption(LM) and lactose intolerance(LI) for a 4SLHBT that acquired four measurements at 0, 90, 120, and 180 min from the same data set were compared with the results of standard LHBT.RESULTS: Sixty IBS-D patients and 60 HVs were studied. The genotype in all participants was C/C-13910. LM and LI detection rates increased with lactose dose from 10 g, 20 g to 40 g in both groups(P < 0.001). 4SLHBT showed excellent diagnostic concordance with standard LHBT(97%-100%, Kappa 0.815-0.942) with high sensitivity(90%-100%) and specificity(100%) at all three lactose doses in both groups.CONCLUSION: Reducing the number of measurements from 13 to 4 samples did not significantly impact on the accuracy of LHBT in health and IBS-D. 4SLHBT is a valid test for assessment of LM and LI in clinical practice.

Study on hydrogen assisted cracking susceptibility of HSLA steel by implant test

DMR-249 A is an indigenously developed high strength low alloy steel for Indian ship building industry for making ship-hull and is extensively used in the construction of war ships and submarines. Welding electrodes conforming to SFA 5.5 AWS E8018 C1 has been indigenously developed for welding of this steel using shielded metal arc welding process. In the present study, susceptibility to hydrogen assisted cracking of DMR-249 A steel welds made using this electrode has been assessed using implant test. Implant tests were conducted using this electrode at two different levels of diffusible hydrogen, measured using gas chromatography technique. It is observed that both the steel and the welding consumable are not susceptible to hydrogen assisted cracking even with a high diffusible hydrogen level of 9 m L/100 g of weld metal. In implant tests, specimen did not fracture even after loading to stress levels higher than the yield strength of the base metal. The good resistance of this steel and the welding consumable, even with high levels of diffusible hydrogen, is attributed to absence of a susceptible microstructure in both the weld metal and heat affected zone. Hence, this study shows that, in the absence of a susceptible microstructure, hydrogen assisted cracking is unlikely to occur even if hydrogen level is high. It also confirms that in welding of DMR-249 A with indigenously developed E8018 C1 electrode, hydrogen assisted cracking is not a concern and no preheating is required to avoid it during welding.

Hydrogen breath test for the diagnosis of lactose intolerance,is the routine sugar load the best one?

AIM: To evaluate the prevalence of lactose intolerance (LI) following a load of 12.5 g in patients diagnosed as high-grade malabsorbers using the hydrogen breath test (HBT)-25.METHODS: Ninety patients showing high-grade malabsorption at HBT-25 were submitted to a second HBT with a lactose load of 12.5 g.Peak hydrogen production,area under the curve of hydrogen excretion and occurrence of symptoms were recorded.RESULTS: Only 16 patients (17.77%) with positive HBT-25 proved positive at HBT-12.5.Hydrogen production was lower as compared to HBT-25 (peak value 21.55 parts per million (ppm) ± 29.54 SD vs 99.43 ppm ± 40.01 SD; P < 0.001).Symptoms were present in only 13 patients.The absence of symptoms during the high-dose test has a high negative predictive value (0.84) for a negative low-dose test.The presence of symptoms during the first test was not useful for predicting a positive low-dose test (positive predictive value 0.06-0.31).CONCLUSION: Most patients with a positive HBT-25 normally absorb a lower dose of lactose and a strict lactose restriction on the basis of a "standard" HBT is,in most instances,unnecessary.Thus,the 25 g lactose tolerance test should probably be substituted by the 12.5 g test in the diagnosis of LI,and in providing dietary guidelines to patients with suspected lactose malabsorption/intolerance.

Epidemiology of small intestinal bacterial overgrowth

Small intestinal bacterial overgrowth(SIBO)is defined as an increase in the bacterial content of the small intestine above normal values.The presence of SIBO is detected in 33.8%of patients with gastroenterological complaints who underwent a breath test,and is significantly associated with smoking,bloating,abdominal pain,and anemia.Proton pump inhibitor therapy is a significant risk factor for SIBO.The risk of SIBO increases with age and does not depend on gender or race.SIBO complicates the course of a number of diseases and may be of pathogenetic significance in the development of their symptoms.SIBO is significantly associated with functional dyspepsia,irritable bowel syndrome,functional abdominal bloating,functional constipation,functional diarrhea,short bowel syndrome,chronic intestinal pseudo-obstruction,lactase deficiency,diverticular and celiac diseases,ulcerative colitis,Crohn’s disease,cirrhosis,metabolic-associated fatty liver disease(MAFLD),primary biliary cholangitis,gastroparesis,pancreatitis,cystic fibrosis,gallstone disease,diabetes,hypothyroidism,hyperlipidemia,acromegaly,multiple sclerosis,autism,Parkinson’s disease,systemic sclerosis,spondylarthropathy,fibromyalgia,asthma,heart failure,and other diseases.The development of SIBO is often associated with a slowdown in orocecal transit time that decreases the normal clearance of bacteria from the small intestine.The slowdown of this transit may be due to motor dysfunction of the intestine in diseases of the gut,autonomic diabetic polyneuropathy,and portal hypertension,or a decrease in the motor-stimulating influence of thyroid hormones.In a number of diseases,including cirrhosis,MAFLD,diabetes,and pancreatitis,an association was found between disease severity and the presence of SIBO.Further work on the effect of SIBO eradication on the condition and prognosis of patients with various diseases is required.

Technology and test results of space adaptability of passive hydrogen maser

Based on the operating principle and the electric property design of the passive hydrogen maser, the technology and test results of its space adaptability are carried out under the special launch conditions and space environment. The various perturbations affecting the output frequency of such a standard used for the navigation satellite system are specified, such as magnetic field change, vibration, thermal vacuum and radiation. Through the adaptability technology in the aspects above, the security and reliability of the space passive hydrogen maser sufficiently fulfill the requirements of space operation. At present, the space passive hydrogen maser is working normally on board, indicating that the space adaptability satisfies the design requirement.

In Vitro Antibacterial Test of Alkaline Hydrogen Water on Four Kinds of Common Pathogenic Microorganisms

[Objective] The paper was to investigate in vitro antibacterial effect of alkaline hydrogen water on Escherichia coli,Salmonella,Pseudomonas aeruginosa and Staphylococcus aureus.[Method] With Cortex cinnamomi extract（1 g/m L） and pure water as the control,the minimal inhibitory concentrations（MIC） against four kinds of common pathogenic microorganisms were tested through microdilution method.[Result] When the alkaline hydrogen water was diluted to 1/8 times of the original concentration,it had significant antibacterial effects on four kinds of common mi-croorganisms with the concentration of 1.5 ×10^5 CFU/m L,which had equivalent effect with C.cinnamomi extract group.[Conclusion]The alkaline hydrogen water has remarkable antibacterial effects on the four kinds of common microorganisms,which may provide a new important way for pre-venting disease occurrence and reducing the harms of pathogenic microorganisms.

Tribological behaviors of hydrogenated diamond-like carbon films in different testing environments

Hydrogenated diamond-like carbon (DLC) films were deposited on Si substrate using plasma enhanced chemical vapor deposition(PECVD) technique with CH4 plus H2 as the feedstock. The tribological properties of the hydrogenated DLC films were measured on a ball-on-disk tribometer in different testing environments (humid air,dry air, dry O2, dry Ar and dry N2 ) sliding against Si3 N4 balls. The friction surfaces of the films and Si3 N4 balls were observed on a scanning electron microscope (SEM) and investigated by X-ray photoelectron spectroscopy (XPS). The results show that the tribological properties of the hydrogenated DLC films are strongly dependent on the testing environments. In dry Ar and dry N2 environments, the hydrogenated DLC films provide a superlow friction coefficient of about 0. 008 -0.01 and excellent wear resistance (wear life of above 56 km). In dry air and dry O2, the friction coefficient is increased to 0. 025 - 0.04 and the wear life is decreased to about 30 km. When sliding in moist air, the friction coefficient of the films is further increased to 0. 08 and the wear life is decreased to 10. 4 km. SEM and XPS analyses show that the tribological behaviors appear to rely on the transferred carbon-rich layer processes on the Si3 N4 balls and on the friction-induced oxidation of the films controlled by the nature of the testing environments.

Early peak of hydrogen during lactose breath test predicts intestinal motility

Lactose breath test (LBT) is considered the gold standard for the diagnosis of lactose malabsorption. The test is considered positive for a peak of hydrogen (H2) ≥ 20 parts per million (ppm) above the baseline. Some patients (pts) showed a rapid peak between 30 and 90 minutes after lactose ingestion. The aim of this study was to evaluate the predictive value of an early peak during a LBT and an accelerated oro-cecal transit time (OCTT). We retrospectively analyzed all pts who referred to our Gastroenterology unit for Irritable Bowel Syndrome, from January to September 2012, who performed LBT, glucose and lactulose breath test. We consider a positive LBT for a peak of H2 > 20 ppm, a positive GHBT for a peak >12 ppm and we considered a normal OCCT a peak of H2 ≥ 10 ppm between 75 ± 105 min after lactulose load. The correlation between LBT and OCTT was evaluated by Pearson score. 93 pts (65 F/28 M mean age 47 ± 6 years) with a positive LBT, without small intestinal bacterial overgrowth were analyzed: 46 pts (32 F/14 M;mean age 48 ± 6 years) with an early peak (2 (≥20 ppm) were enrolled as case, and 47 pts matched for sex and age with a peak of H2 after 90 min were enrolled as controls. 72% (33/46) of the group with an early peak showed an accelerated, 17% (8/46) a normal and 11% (5/46) a delayed OCTT. Meanwhile, in control group 40.4% (19/47) showed a normal, 57.5% (27/47) a delayed and just 1 pts an accelerated OCTT. The specificity and sensibility of LBT for an accelerated OCTT were 97.9% and 71.7% respectively. The positive predictive value of LBT for an accelerated OCTT is 97.1%;the negative predictive value is 78%. There is a significant correlation between LBT and OCTT (p The presence of an early peak of H2 between 30 and 90 min after the ingestion of 25 gr of lactose could predict the presence of an accelerated OCTT in 97% of pts. If confirmed by further study, in this subset of pts, lactulose breath test for evaluating OCTT could be avoided.

Glucose substrate in the hydrogen breath test for gut microbiota determination:A recommended noninvasive test

Intestinal dysbiosis and small intestinal bacterial overgrowth(SIBO)are common in patients with liver cirrhosis.Existing studies have not explored the association between gut dysbiosis and SIBO.We propose some suggestions for the authors’experimental methods and concepts,and we hope these suggestions can be adopted.The hydrogen breath test is worthy of recommendation due to its high accuracy and convenient operation.We suggest changing the substrate of the hydrogen breath test from lactulose to glucose to improve the accuracy of each parameter.SIBO is a small subset of gut dysbiosis,and we propose clarifying the concept of both.SIBO may be caused by liver cirrhosis or one of the pathogeneses of gastrointestinal diseases.Therefore,interference from other gastrointestinal diseases should be excluded from this study.

Hydrogen Shows Promise in Vehicle Tests

Car fleets escorted by police along Chang’an Avenue are not a rare sight for Beijing residents, who are accustomed to the practice when leaders of foreign states visit the capital of China.

Progress in Diagnosis and Treatment of Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth has been found to be associated with a variety of gastrointestinal disorders such as irritable bowel syndrome, inflammatory bowel disease, and, in recent years, diabetes mellitus and systemic sclerosis, among other extraintestinal diseases. Several novel diagnostic tools for small intestinal bacterial overgrowth have emerged in recent years, and several therapeutic approaches have been proposed. Therefore, it has become necessary to find an effective, safe, and simple diagnostic method and a safe treatment modality. This article provides a review of current diagnostic and therapeutic approaches to small intestinal bacterial overgrowth.

3D fluid model analysis on the generation of negative hydrogen ions for negative ion source of NBI

A radio-frequency(RF) inductively coupled negative hydrogen ion source(NHIS) has been adopted in the China Fusion Engineering Test Reactor(CFETR) to generate negative hydrogen ions.By incorporating the level-lumping method into a three-dimensional fluid model,the volume production and transportation of H^(-) in the NHIS,which consists of a cylindrical driver region and a rectangular expansion chamber,are investigated self-consistently at a large input power(40 k W) and different pressures(0.3–2.0 Pa).The results indicate that with the increase of pressure,the H^(-) density at the bottom of the expansion region first increases and then decreases.In addition,the effect of the magnetic filter is examined.It is noteworthy that a significant increase in the H^(-) density is observed when the magnetic filter is introduced.As the permanent magnets move towards the driver region,the H^(-) density decreases monotonically and the asymmetry is enhanced.This study contributes to the understanding of H-distribution under various conditions and facilitates the optimization of volume production of negative hydrogen ions in the NHIS.

中子成像技术在元素分析中的应用

中子成像作为一种快速、直观的无损检测技术,在核工业、航空航天、新能源、地质、考古、先进制造等多个领域得到广泛应用。中子成像利用中子不带电、穿透能力强、对轻元素敏感、可区分同位素和近邻元素等特性,非常适合开展含氢元素、近邻元素和同位素等材料的无损检测。通过概述中子成像技术的基本原理及特点,并结合中国先进研究堆(CARR)中子成像装置上的应用案例,重点综述了国内外中子成像技术在储氢材料、燃料电池、岩石、核燃料元件、古代文物等领域的典型应用。随着中子成像技术的不断发展和广泛应用,有望为我国更多领域研究提供更强有力的技术支撑。

T23/P23钢高强匹配焊缝金属接头再热裂纹表征

综述了T23/P23钢高强匹配焊缝金属接头再热裂纹的特征。结果表明,T23/P23耐热钢高强匹配接头再热裂纹倾向明显,焊后状态高强匹配接头具有较高的强度和可以接受的塑性和韧性。接头显微组织中的HAZ粗晶区碳化物析出、晶界的滑移及晶界的脆化是再热裂纹产生的必要条件;影响HAZ组织的主要因素是母材中碳化物形成元素和残留元素的种类及含量。随接头拘束应力增大,再热温度升高时再热裂纹倾向增大。T23/P23钢接头中氢的行为是产生再热裂纹不可忽视的影响因素。生产中常用低应力化和低氢化综合工艺及参数,以及新型专用焊接材料等措施,使接头中的应力水平降低,氢含量最小化,控制再热裂纹形成条件,并获得了较满意的效果。

条形缺陷对L360管线钢环焊缝硫化物应力腐蚀开裂敏感性的影响

通过抗硫化物应力腐蚀试验、慢应变速率拉伸试验、氢含量测试等方法研究条形缺陷对H_(2)S环境下L360管线钢环焊缝硫化物应力腐蚀开裂敏感性的影响。结果表明,环焊缝在72%、85%和110%SMYS(最小屈服强度)应力水平下,热影响区出现裂纹且裂纹长度随加载应力增大而增大;条形缺陷环焊缝试样在屈服点后快速发生断裂,其断裂应变(0.024)仅为非缺陷环焊缝试样的21.05%;条形缺陷存在促进氢离子在裂纹尖端聚集从而加剧发生开裂倾向,消氢处理技术可以有效降低氢含量,降低环焊缝抗硫化物应力腐蚀开裂敏感性降低。

中国散裂中子源伴生质子辐照实验平台及其技术参数的确定

为了利用负氢离子加速器中伴随产生的质子成分,中国散裂中子源(China Spallation Neutron Source,CSNS)在直线加速器末端建设了伴生质子辐照实验平台(associated protons experimental platform,APEP)。为了确定其性能参数,采用散射测量、束斑照相、同位素活化法等实验方法对伴生质子辐照实验平台的主要参数进行了刻度。实验证实,该辐照平台可以提供的质子能量范围为10~80 MeV,束斑分布均匀,束流强度范围为1.2×10^(7)~4.0×10^(9) cm^(-2)·s^(-1)。伴生质子辐照实验平台运行稳定,每年提供超过5000 h的束流时间,可以满足宇航器件可靠性测试、探测器刻度、辐照育种以及材料抗辐照特性测试等多种应用需求。

车载储氢气瓶气密性试验关键参数研究

车载储氢气瓶作为氢气的重要载体,必须根据相关标准和技术规范进行型式试验,其中,气密性试验是检验车载储氢气瓶泄漏情况的重要环节。虽然国内外颁布的相关标准对气密性试验关键试验参数提出的不同程度的要求,但现行标准对部分试验参数并未提出定量的要求,且缺乏理论依据和数据支撑。基于数值仿真模型,结合试验结果进行验证,分析气瓶气密性试验过程的流场分布特性,结合气密性试验表征参量,研究关键试验参数对气瓶气密性试验结果的影响并获得试验参数优化值。结果表明:(1)随着增压速率的增大,气瓶的压降时间整体呈现出逐渐增加的趋势,且当增压速率大于3 MPa/min时增加幅度尤为明显;(2)随着保压时间的增加,气瓶的压差百分比和压降时间呈现先增加,并在保压时间大于90 s时不再发生变化;(3)当充装温度越低,气瓶气密性试验结果越准确;(4)当试验介质氮气和氦气的比例相近时,气瓶的压降时间和压差百分比最小。

高压临氢金属材料的氢相容性测试技术

金属材料在高压氢环境下可能存在高压氢脆现象,对氢能高压储输装备的安全使用产生威胁,在高压氢环境下开展氢相容性测试是获得材料临氢力学性能、预防装备因高压氢脆引起失效的有效手段。该文总结了金属材料的氢脆理论,从测试原理、测试标准及应用场景等方面系统梳理了高压氢环境下金属材料氢相容性的测试方法,并介绍了测试装置及测试流程。最后以4130X钢为例,开展了空气和50 MPa氢气下的疲劳裂纹扩展速率测试。测试结果表明,高压氢气对4130X的疲劳裂纹扩展有明显加速作用,且加速程度随着裂纹的扩展逐渐增大并趋于稳定,最终氢环境下的疲劳裂纹扩展速率达到空气下的近20倍。