Effect of sample type,centrifugation and storage conditions on vitamin D concentration

Introduction:

Studies about vitamin D [25(OH)D] stability in plasma are limited and preanalytical variables such as tube type may affect results. We aimed to evaluate effect of storage conditions, sample type and some preanalytical variables on vitamin D concentration.

Materials and methods:

Blood samples from 15 healthy subjects were centrifuged at different temperatures and stored under different conditions. Serum and plasma 25(OH)D difference, effect of centrifugation temperature and common storage conditions were investigated.

Results:

There was no difference between serum and plasma vitamin D concentration. Centrifugation temperature had no impact on vitamin D concentration. 25(OH)D is stable under common storage conditions: 4 hours at room temperature, 24 hours at 2–8 °C, 7 days at −20 °C, 3 months at −80 °C.

Conclusion:

Vitamin D does not require any special storage conditions and refrigeration. Both serum and plasma can be used for measurement.     

Stability studies of common biochemical analytes in serum separator tubes with or without gel barrier subjected to various storage conditions

Introduction

The collected and shipped blood samples are exposed to a various extra-analytical factors prior to analysis. The aim of the study was to determine the stability of analytes in serum gel tubes and plain tubes exposed to a range of storage temperatures and times after centrifugation.

Materials and methods:

Fifteen healthy volunteers were recruited and venous blood was collected into four tubes, two with and two without gel separator. Analyzing the baseline samples in 30 min, all were stored at 4ºC or 24ºC for 6, 12, 18, 24, 30, 36, 48 and 72 hours and 1 week. Sixteen biochemical anaytes were measured on each sample. Variations remained under the desirable bias considered as clinically insignificant.

Results:

On day three, most analytes remained stable including albumin, protein, creatinine, cholesterol, triglycerides, gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), alanine aminotransferase (ALT), creatine kinase (CK), lactate dehydrogenase (LD) regardless of tube types. Glucose concentration decreased markedly (P = 0.001) beginning from the first hours of storage in plain serum. The stability maximized for the analytes including glucose, total bilirubin, urea nitrogen (BUN), uric acid stored at 4 ºC in gel tubes. Aspartate aminotransferase (AST) activity increased significantly (P = 0.002) up to 48-h, however bias was not significant clinically. High density lipoprotein (HDL) concentration was stable in gel tubes at 24 ºC, in plain tubes at 4 ºC stored up to 36-h.

Conclusion:

Serum gel or non-gel tubes might be used interchangeably for 11 analytes chilled or at 24 ºC, whereas some restrictions must be applied for glucose, AST, BUN, HDL, and uric acid.     

The effective reduction of tourniquet application time after minor modification of the CLSI H03-A6 blood collection procedure

Introduction:

The phlebotomists’ procedures are a still source of laboratory variability. The aim of this study was to verify the efficacy of minor modification in procedure for collection of diagnostic blood specimens by venipuncture from CLSI H03-A6 document is able to reduce the tourniquet application time.

Materials and methods:

Thirty phlebotomists were invited to participate. Each phlebotomist was trained individually to perform the new venipuncture procedure that shortens the time of tourniquet release and removal. The phlebotomy training program was delivered over 8h. After training, all phlebotomists were monitored for 20 working days, to guarantee the adoption of the correct new procedures for collection of diagnostic blood specimens. After this time frame the phlebotomists were evaluated to verify whether the new procedure for blood collection derived from CLSI H03-A6 document was effective to improve the quality process by decrease in tourniquet application time. We compared the tourniquet application time and qualitative difference of phlebotomy procedures between laboratories before and after phlebotomy training.

Results:

The overall mean ± SD tourniquet application time before and after this intervention were 118 ± 1 s and 30 ± 1 s respectively. Minor modifications in procedure for blood collection were able to reduce significantly the tourniquet application time (−88 s, P < 0.001).

Conclusions:

The minor modifications in procedure for collection of diagnostic blood specimens by venipuncture from CLSI H03-A6 document were able to reduce the tourniquet application time. Now the proposed new procedure for collection of diagnostic blood specimens by venipuncture could be considered usefulness and should be put into practice by all quality laboratory managers and/or phlebotomy coordinators to avoid preanalytical errors regard venous stasis and guarantee patient safety.     

农户仓类设施采纳及其对玉米储存数量和损失的影响

近年来,粮食增产难度提升,减少粮食损失成为保障国家粮食安全的重要内容。中国政府通过实施科学储粮工程,鼓励农户采用更为先进的设施储粮,改善储粮设施和储藏条件,减少损失。本文基于中国23省（区、市）1202户农户调查数据,使用倾向性得分匹配法评估仓类设施采纳对农户玉米储存规模、储存时间、储存损失和鼠害程度的影响。结果表明：①采用仓类设施显著提升农户玉米储存数量,使农户平均玉米储存规模达4655.30 kg,比没有采用的农户高1188.77~1368.55 kg,并延长农户玉米储存时间0.2个季度;②采用仓类设施显著减轻玉米储存过程中的鼠害,使玉米储存损失数量降低60%,减少的损失使农民平均节约玉米28~33 kg,玉米储存损失率由2.75%下降到0.87%。因此,国家应继续实施科学储粮工程,鼓励更多的农户采用科学储粮设施,降低储粮损失。     

Stability of total and free prostate specific antigen in serum samples at different storage conditions

The present preliminary study was performed to find out stability of total prostate specific antigen (PSA) and free prostate specific antigen (FPSA) in serum of healthy males as well as in patients of benign and malignant disorders of prostate at various freezing and nonfreezing temperatures and at different duration of time. The results of our study indicated long-term stability of both the analytes in frozen serum. Serum total and free PSA were stable only for three to four days in regular refrigerators in unfrozen states. Clotted blood kept at room temperature (25°C–30°C) did not cause change in concentrations of both the analytes for twenty four hours.     

蚝油酶水解产物及其稳定性的初探

对蚝油酶水解产物及其稳定性进行了初步研究,结果表明：在最佳酶解条件下,蚝干的解产物（水解液及潭的混合物）中加盐保温,全氮利用率大幅度提高;以进口淀粉６－７为主要增稠剂,并配以卡拉胶,可得到色泽、体态、风味、稳定性良好的蚝油调味品。     

数字图书馆的云存储性能研究与研讨

首先,介绍一个开源的、免费的、可行的云环境下的数字图书馆存储构架;接下来,对云存储的关键复制技术逐一叙述,并构建数字图书馆的现实中云存储构架;最后,详细的测试和分析不同云存储之间的性能差异,探讨了数字图书馆在云环境下的存储领域的应用。     

隧道锚碇围岩稳定分析及破坏模式研究

锚碇围岩稳定性及破坏模式研究是确定系统极限承载力的基础。基于现场地质资料的数值仿真计算与现场缩尺模型试验对比分析,被认为是一种比较理想的研究思路。通过FLAC3D计算发现,在设计荷载下,围岩的应力场和位移场具有明显的分区特征,在锚体空腔和结构拐角处常出现应力集中和大变形区,系统整体未形成连贯的破坏区,出现的局部破损区主要集中在锚体后部右上角等5个部位。超载数值试验发现,破坏并不是简单的沿锚体和岩体的边界发生滑移,而是带动周边岩体发生倒塞型的整体拉剪复合破坏。现场模型试验结果与数值计算结果吻合较好。施工及运营过程中应对易破坏区进行重点加固处理。     

基于KMRW声誉模型的渠道联盟稳定性研究

摘要：从20世纪80年代开始,渠道联盟成为了营销渠道发展的一个重要方向,这当中,稳定性又成为联盟研究的一个核心内容。但渠道联盟稳定性的研究还鲜有学者涉猎,大部分学者集中于战略联盟稳定性研究,一部分学者专注于供应链联盟稳定性的研究。在解决联盟不稳定的策略上,上述研究要么过分关注“利益解决机制”,而忽视对“声誉解决机制”的研究;要么只关注了“纵向渠道联盟”的研究,而忽视“横向渠道联盟的研究。要保证渠道联盟的顺利运行,核心问题之一是依靠联盟成员间的相互监督、相互激励,而这种监督与激励是建立在联盟成员间信息的识别与传递之上的,声誉正是这种识别与传递过程的外在表现。声誉机制能约束和识别非合作成员,减少伪装合作成员数量,从而制约联盟内机会主义行为的发生,保持联盟的稳定,但声誉机制的发挥需要一定的条件。针对联盟成员合作出现的一些问题,笔者提出了维持渠道联盟稳定性的几点建议和需要进一步研究的问题。     

计量标准的重复性和稳定性考核方法探讨

分析计量标准的稳定性和重复性,以确保计量标准传递的安全可靠。     

Delay-dependent exponential stability for a class of neural networks with time delays and reaction-diffusion terms

In this paper, the exponential stability of a class of delayed neural networks described by nonlinear delay differential equations of the neutral type has been studied. By constructing appropriate Lyapunov functional and using the linear matrix inequality (LMI) optimization approach, a series of sufficient criteria is obtained ensuring the existence, uniqueness and global exponential stability of an equilibrium point of such a kind of delayed neural networks. These conditions are dependent on the size of the time delay and the measure of the space, which is usually less conservative than delay-independent and space-independent ones. And, these networks are generalized without assuming the boundedness and differentiability of the activate functions. The proposed LMI condition can be checked easily by recently developed algorithms. The results are new and improve the earlier work. Examples are provided to demonstrate the effectiveness and applicability of the proposed criteria.     

Existence and global exponential stability of equilibrium of competitive neural networks with different time scales and multiple delays

In this paper, some sufficient conditions are obtained for existence and global exponential stability of a unique equilibrium point of competitive neural networks with different time scales and multiple delays by using nonlinear Lipschitz measure (NLM) method and constructing suitable Lyapunov functional. The results of this paper are new and they complete previously known results.     

中小企业创新网络稳定性及其效率分析

本文提出了中小企业创新网络的概念,对比分析了中小企业创新网络五种常见模式,指出了中小企业创新网络的五大特性,分析了中小企业创新网络的冲突周期及其稳定性,最后从三个视角探讨了中小企业创新网络效率改进以及中小企业的应对措施。     

某边坡稳定性计算与评价

以某边坡为工程背景,分析了边坡稳定性的宏观地质表现,边坡整体稳定性情况,并反演了滑面上的参数,包括了粘结力和内摩擦角,表明：现场大剪试验较为接近实际情况,东区及西区部分地段有滑带,但无明显滑面,较现场试验隋况稍好一点,对不同情况建议了不同的粘结力和内摩擦角。     

产学研合作创新稳定性研究

产学研合作创新是科技成果产出和转化的有效途径,对科技创新和经济发展具有重要作用。本文基于扎根理论探索了涵盖项目对接、合作研发、试验试制和产业化四个阶段产学研合作创新全过程的稳定性影响因素;在此基础上,采用生存分析方法对2004—2013年期间产学研合作创新稳定性及影响因素进行分析,结果表明:50%左右企业的产学研合作创新持续时间约为3年;在不同性质的企业、不同的合作方式以及不同的利益分配方式条件下,产学研合作创新持续时间是有显著差异的;知识资源互补性、合作声誉、沟通交流以及合作态度对产学研合作创新稳定性具有积极促进作用,而科研实力和地理距离对产学研合作创新稳定性的推动作用不显著。     

虚拟存储技术的网络化实现及应用

随着信息数字化、网络化技术的发展,存储平台在信息系统中的地位越来越重要。虚拟存储技术的使用,推动了现代图书情报系统的集成化、共享化。本文简要介绍了虚拟存储的概念、网络化实现过程和几种的虚拟存储解决方案的实际应用。     

油气储运系统节能技术研究

在石油加工和生产的过程中,油气储运系统对其具有极其重大的意义。由于油气储运系统消耗了巨大的能量,对油气储运系统的能耗进行有效的控制是刻不容缓的。文章通过探讨油气储运系统的节能技术,对存在的三方面原因提出了三大技术改进措施,并对其进行深入研究和分析。     

基于GF-1 WFV影像的丰宁县植被地上碳储量估算

陆地植被碳储量的定量估算及其空间分布研究有助于了解区域碳平衡,为增汇减排管理及可持续发展提供科学依据。本文以河北省丰宁县为研究区,结合新型国产高分遥感影像GF-1 WFV 和2015年同步野外实测数据,分别建立基于植被指数的森林、灌丛和草地植被地上生物量一元曲线回归模型及多元线性回归模型,选择最优反演模型计算地上生物量,进一步估算植被地上碳密度和碳储量,并结合GIS技术分析其空间分布特征。结果表明：①所建立的多元回归模型对森林和草地植被生物量有较好的反演精度,R²分别为0.528和0.777,基于RVI的指数方程是估算灌丛生物量最佳模型,R²为0.620;②研究区2015年8月森林、灌丛和草地地上植被碳密度估算值分别为55.406tC/hm²、3.304tC/hm²和0.533tC/hm²,碳储量分别为15.714TgC、1.016TgC和0.080TgC,除农田植被外,植被地上碳储量总量为16.810TgC,森林植被为主要碳库;③丰宁县植被碳密度呈现随海拔升高而先升高后降低的趋势,植被地上碳库主要集中在海拔700~1500m之间。     

平房仓偏高水分粮低温保湿储粮试验

通过采用各种形式的隔热密闭控温保湿措施,能够有效地控制平房仓偏高水分粮品质变化,最大限度地延缓储粮陈化,保持新鲜度,达到安全储藏的目的。     

广西农户储粮现状及专项工作实施建议

文章阐述了广西的农户储粮技术现状,对存在问题进行了分析,介绍农户储粮装置的研发情况,对广西开展农户科学储粮专项活动提出了一些工作建议。