Effects of high-volume hemofiltration on alveolar- arterial oxygen exchange in patients with refractory septic shock

BACKGROUND：High-volume hemofiltration （HVHF） is technically possible in severe acute pancreatitis （SAP） patients complicated with multiple organ dysfunction syndrome （MODS）. Continuous HVHF is expected to become a beneficial adjunct therapy for SAP complicated with MODS. In this study, we aimed to explore the effects of fluid resuscitation and HVHF on alveolar- arterial oxygen exchange, the Acute Physiology and Chronic Health Evaluation II （APACHE II） score in patients with refractory septic shock. METHODS：A total of 89 refractory septic shock patients, who were admitted to ICU, the Provincial Hospital affiliated to Shandong University from August 2006 to December 2009, were enrolled in this retrospective study. The patients were randomly divided into two groups： fluid resuscitation （group A, n=41）, and fluid resuscitation plus high-volume hemofiltration （group B, n=48）, The levels of O2 content of central venous blood （CcvO2）, arterial oxygen content （CaO2）, alveolar-arterial oxygen pressure difference P（A-a）DO2, ratio of arterial oxygen pressure/alveolar oxygen pressure （PaO2/ PAO2）, respiratory index （RI） and oxygenation index （OI） were determined. The oxygen exchange levels of the two groups were examined based on the arterial blood gas analysis at different times （0, 24, 72 hours and 7 days of treatment） in the two groups. The APACHE II score was calculated before and after 7-day treatment in the two groups. The levels of CcvO2, CaO2 on day 7 in group A were significantly lower than those in group B （CcvO2：0.60±0.24 vs, 0.72±0.28, P〈0.05; CaO2：0.84±0.43 vs. 0.94±0.46, P〈0.05）. The level of oxygen extraction rate （O2ER） in group A on the 7th day was significantly higher than that in group B （ 28.7±2.4 vs. 21.7±3.4, P〈0.01）. The levels of P（A-a）DO2 and RI in group B on the 7th day were significantly lower than those in group A. The levels of PaO2/PAO2 and OI in group B on 7th day were significantly higher than those in group A （P〈0.05 or P〈0.01）. The APACHE II score in the two groups reduced gradually after 7-day treatment, and the APACHE II score on the 7th day in group B was significantly lower than that in group A （8.2±3.8 vs. 17.2±6.8, P〈0.01）. HVHF combined with fluid resuscitation can improve alveolar- arterial-oxygen exchange, decrease the APACHE II score in patients with refractory septic shock, and thus it increases the survival rate of patients.

CORRELATIONS BETWEEN OXY-HEMOGLOBIN AND RESPIRATORY EXCHANGE RATIO IN THE QUADRICEPS DURING THE EARLY PHASE OF EXERCISES

The early stage of exercises is crucial in sports training;however,its physiological mechanism is still unclear.The hemodynamic response was reported to be associated with respiratory exchange.Here,we aimed to explore the relationship between oxy-hemoglobin concentration change(HbO_(2))and respiratory exchange ratio(RER)during the early phase of exercises.Sixteen athletes of middle-distance race were selected from Wuhan Institute of Physical Education to conduct intermittent exercises on MERCURY4.0 at 80%VO_(2)peak intensity.Multiple physiological parameters were acquired by use of a near-infrared spectroscopy muscle oxygen monitor,a Cardiopulmonary Function MAX-II and a P-Lar,including HbO_(2),RER and others.A significant correlation was found between RER and HbO_(2)in quadriceps muscle in the thigh during the early phase of exercises.Thus,NIRS is capable of supervising sports training in terms of HbO_(2),which actually acted as an interpreter of RER change.

Development of high-aspect-ratio microchannel heat exchanger based on multi-tool milling process

A high-aspect-ratio microchannel heat exchanger based on multi-tool milling process was developed. Several slotting cutters were stacked together for simultaneously machining several high-aspect-ratio microchannels with manifold structures. On the basis of multi-tool milling process, the structural design of the manifold side height, microchannel length, width, number, and interval were analyzed. The heat transfer performances of high-aspect-ratio microchannel heat exchangers with two different manifolds were investigated by experiments, and the influencing factors were analyzed. The results indicate that the magnitude of heat transfer area per unit volume dominates the heat transfer performances of plate-type micro heat exchanger, while the velocity distribution between microchannels has little effects on the heat transfer performances.

Effects of Heat Exchange Tube Structural Parameters on Performance of Vehicle Radiator

In order to improve the performance of vehicle radiators, a two-dimensional heat transfer steady-state model of the radiator was set up. The influence of the structural parameters (axial ratio) of the heat exchange tube on the windward side on the heat transfer performance of the radiator was studied. With the increase of the axial ratio of the heat exchange tube on the windward side, the heat exchange capacity of the heat exchange tube surface slightly decreases. The heat exchange area increases significantly, which increases the total heat exchange of the radiator and improves the heat transfer performance of the radiator. When the axial ratio increases from 1.0 to 2.0, the average surface heat transfer capacity decreases from 5664.16 W/m2 to 5623.57 W/m2.

Delisting in Athens Stock Exchange

The scope of this paper is to contribute to the question of delisting (both voluntary and involuntary), with particular emphasis on the initial conditions leading up to the Initial Public Offering (IPO) of the firms. The case of Athens Stock Exchange (ASE) is examined, specifically the IPOs of years 1996-2004 and their subsequent performance (delisting or not) till the end of 2017. We find that the probability of delisting is positively associated with the size of the issuance and the degree of earnings’ manipulation and negatively associated with audit quality, information transparency, and market timing. The effects of audit quality, size of issuance, and earnings’ manipulation are accentuated in instances of voluntary delisting while the effect of market timing is more clearly pronounced in instances of involuntary delisting. Our results are robust to a number of confounding factors including size, profitability, leverage, liquidity, growth options, and corporate governance. Our work is not replication of existing studies;in addition, we choose ASE as in that capital market there were many delistings the last two decades.

The Golden Ratio Theorem: A Framework for Interchangeability and Self-Similarity in Complex Systems

The Golden Ratio Theorem, deeply rooted in fractal mathematics, presents a pioneering perspective on deciphering complex systems. It draws a profound connection between the principles of interchangeability, self-similarity, and the mathematical elegance of the Golden Ratio. This research unravels a unique methodological paradigm, emphasizing the omnipresence of the Golden Ratio in shaping system dynamics. The novelty of this study stems from its detailed exposition of self-similarity and interchangeability, transforming them from mere abstract notions into actionable, concrete insights. By highlighting the fractal nature of the Golden Ratio, the implications of these revelations become far-reaching, heralding new avenues for both theoretical advancements and pragmatic applications across a spectrum of scientific disciplines.

水平挡板流场对燃料电池性能与传质的影响

在质子交换膜燃料电池(PEMFC)流道内设置微结构,可增强反应气体从流道到催化层的传质能力,并提高电池性能。建立并对比交错安装挡板与对置安装挡板的模型,得出交错安装的布置方式,更有利于电池性能的提升。建立4种不同堵塞率的模型,发现随着堵塞率的升高,电池的最大净功率密度和极限电流密度增大,95%堵塞率模型的净功率密度最高,为1.053 W/cm^(2),较无挡板模型提升了14.58%,直至电流密度2.8 A/cm^(2)时,仍未出现明显的浓差极化。调整挡板夹角,综合考虑传质能力和泵送损失情况下,夹角为15°时,电池净功率密度最高。

长期施用有机肥对松嫩平原盐碱土壤盐碱性质和化学计量比的影响

盐碱土盐碱化程度高、养分有效性低,施加有机肥可以促进土壤盐分淋洗,降低土壤盐碱化程度,增加养分含量和土壤碳、氮、磷的供应能力。根据土壤施加腐熟牛粪的年限,设置施加腐熟牛粪21(Y21)、18(Y18)、15年(Y15)和未施加腐熟牛粪(CK)共4个处理,采集各处理0—20和20—40 cm土层的土壤样品,分析土壤盐碱性质和养分含量。结果表明,0—20和20—40 cm土层Y21、Y18、Y15处理有机碳(soil organic carbon,SOC)、全氮(total-N,TN)和全磷(total-P,TP)含量显著高于CK;土壤水溶性盐离子、pH、电导率(electrical conductance,EC)、钠吸附比(sodium adsorption ratio,SAR)和碱化度(exchangeable sodium percentage,ESP)较CK显著降低。在0—20和20—40 cm土层,Y21、Y18、Y15处理碳氮比(C/N)较CK显著降低;与CK相比,Y21与Y15处理0—20 cm土层氮磷比(N/P)由0.95显著增加至1.84和2.11,20—40 cm土层N/P由1.15显著增加至2.25和2.44;土壤碳磷比(C/P)在0—20 cm土层规律不明显,在20—40 cm土层Y21、Y18、Y15处理与CK相比差异不显著。多元线性回归模型显示,C/N受SOC、TN和ESP影响,N/P和C/P主要受TP和TN影响。综上所述,松嫩平原西部草甸碱土施加有机肥后土壤盐碱程度降低,SOC、TN、TP含量和N/P增加,C/N降低,且施加有机肥改良15年的土壤供碳、供氮潜力达到最大。

土壤源热泵地埋管侧水系统优化运行研究

本文基于江苏无锡某典型厂房土壤源热泵空调项目的实测数据,以地源侧系统总能耗最低为目标,构建设备模型对地源水泵运行工况进行优化,并与两种传统控制策略的运行效果进行对比,据此提出进一步的优化建议。结果表明:基于负荷的优化控制策略,其节能效果要明显优于定频控制策略,冬夏季典型测试日平均节能率分别为28.33%和13.27%,相比于5℃温差变频策略节能了3.61%和2.21%。适当增大地埋管的埋管深度或管径,可以进一步提升该优化控制策略的节能效果。传统的定温差控制策略在负荷率大于60%时,可在5℃基础上将温差增加1~5℃以提升节能效果。

“离子交换法”测定硝酸盐氧同位素组成方法的改进

硝酸盐氮、氧同位素组成(δ^(15)N、δ^(18)O)被广泛应用于识别水体中硝酸盐的来源及其生化转化过程.离子交换技术作为主要分析方法之一,被大量应用于测定硝酸盐的氮同位素组成,然而在测定氧同位素组成时,由于该方法的样品处理过程复杂繁琐、耗时长(3~5天)等缺点限制了它的广泛应用.通过对原技术路线进行改进:将定量的BaCl_(2)直接加入到野外采集的水样中,消除含氧阴离子(SO_(4)^(2-)和PO_(4)^(3-))对测定NO_(3)^(-)离子δ^(18)O的干扰,然后再通过阴离子交换树脂吸附富集、HCl洗脱NO_(3)^(-)、Ag_(2)O中和,得到用于测试δ^(18)O的AgNO_(3)样品.与原路线相比,改进后方法的优势在于:(1)样品处理步骤由原来的5步缩短到了3步;(2)样品处理时长由3~5天缩短至1~2天;(3)减少了昂贵的化学试剂的用量;(4)减少了同位素的分馏.

稻秆生物炭对水体Pb^(2+)的吸附特性及机制定量化

采用吸附等温线和动力学等方法阐明了稻秆生物炭对水体Pb^(2+)的吸附特性,并通过元素分析、BET(Brunauer-Emmet-Teller)-N_(2)比表面积分析、Zeta电位、扫描电镜-能谱仪、傅立叶变换红外光谱、X射线衍射和X射线光电子能谱等分析手段,结合机制贡献比例计算方法,定性和定量地揭示了生物炭吸附机制。结果表明,在不同吸附温度20、30、40℃下,生物炭对Pb^(2+)的最大吸附量分别为233.48、236.00、237.50 mg/g,均符合Langmuir模型(R^(2)>0.96),属于单分子层吸附;当初始Pb^(2+)浓度为50、100、300 mg/L时,生物炭吸附平衡时间分别为30、90、360 min,均符合准二级动力学模型(R^(2)>0.95),以化学吸附为主。生物炭对Pb^(2+)吸附机制主要包括化学沉淀、离子交换、官能团络合和Cπ电子配位等4种作用,其中化学沉淀产物可能以Pb_(4)(CO_(3))_(2)(SO_(4))(OH)_(2)和PbCO_(3)为主,贡献比例为47.15%~50.81%,离子交换主要以Ca^(2+)和Mg^(2+)为主,贡献比例为32.82%~37.77%,这两者共同贡献比例范围为83.63%~84.92%,其余2种吸附机制共同占比15.03%~16.37%。生物炭对Pb^(2+)具有优良的吸附能力,可作为水体中重金属的优势吸附材料之一。

参苓白术散对腹泻幼鼠模型肠黏膜通道蛋白的影响及机制研究

目的探讨参苓白术散对腹泻幼鼠模型肠黏膜通道蛋白的影响及机制。方法将腹泻幼鼠模型(n=42,采用番泻叶药液灌胃进行建模)随机平分为三组,分别为模型组、低剂量参苓白术散组、高剂量参苓白术散组,三组分别给予参苓白术散0.0 g/kg(即0.9%氯化钠溶液)、1.2 g/kg、4.6 g/kg灌胃治疗,给药体积均为10 mL/kg,连续用药14 d,检测幼鼠肠黏膜通道蛋白-水通道蛋白8(AQP8)、跨膜转运蛋白钠氢交换体3(NHE3)囊性纤维化跨膜传导调节因子(CFTR)表达变化情况,观察幼鼠体质量、尿液乳果糖和甘露醇比值、小肠组织绒毛长度等变化情况。结果低剂量参苓白术散组、高剂量参苓白术散组治疗第7天、第14天的幼鼠体质量明显高于模型组(P<0.05),腹泻指数与模型组相比明显降低(P<0.05),高剂量参苓白术散组与低剂量参苓白术散组对比,差异有统计学意义(P<0.05)。低剂量参苓白术散组、高剂量参苓白术散组治疗第7天、第14天的尿液乳果糖和甘露醇比值明显低于模型组(P<0.05),高剂量参苓白术散组也低于低剂量参苓白术散组(P<0.05)。低剂量参苓白术散组、高剂量参苓白术散组治疗第14天的小肠组织绒毛长度高于模型组(P<0.05),隐窝深度明显低于模型组(P<0.05),高剂量参苓白术散组与低剂量参苓白术散组对比,差异有统计学意义(P<0.05)。低剂量参苓白术散组、高剂量参苓白术散组治疗第14天的小肠组织AQP8蛋白、NHE3蛋白相对表达水平高于模型组(P<0.05),CFTR蛋白相对表达水平低于模型组(P<0.05),低剂量参苓白术散组与高剂量参苓白术散组对比,差异有统计学意义(P<0.05)。结论参苓白术散在腹泻幼鼠模型中的应用能促进体质量的恢复,降低尿液乳果糖和甘露醇比值与腹泻指数,还可延长小肠组织绒毛长度与降低隐窝深度,同时可促进小肠组织AQP8蛋白、NHE3蛋白的表达,抑制CFTR蛋白的表达。

Fluid flow and heat transfer characteristics of spiral coiled tube: Effects of Reynolds number and curvature ratio

Numerical analysis was performed to investigate flow and heat transfer characteristics in spiral coiled tube heat exchanger. Radius of curvature of the spiral coiled tube was gradually increased as total rotating angle reached 12n. As the varying radius of curvature became a dominant flow parameter, three-dimensional flow analysis was performed to this flow together with different Reynolds numbers while constant wall heat flux condition was set in thermal field. From the analysis, centrifugal force due to curvature effect is found to have significant role in behavior of pressure drop and heat transfer. The centrifugal force enhances pressure drop and heat transfer to have generally higher values in the spiral coiled tube than those in the straight tube. Even then, friction factor and Nusselt number are found to follow the proportionality with square root of the Dean number. Individual effect of flow parameters of Reynolds number and curvature ratio was investigated and effect of Reynolds number is found to be stronger than that of curvature effect.

An Influencing Factor - Water-Filter Ratio on Heat Resistance of Condensate Polishing Filter Material in Water

In air-cooled condenser, high temperature condensing water m summer which approaching and exceed 60＊ C, which may result in filter materials degradation and release impurities. This paper discusses an influencing factor, water-filter ratio （soaking solution and filter quality ratio）, on leachable dissolution rate and filter material degradation rate m high temperature water. The UV absorption at 254nm （A254） and the exchange capacity ware measured after heat test as composite indicators. In addition, the Wends of A254 variation with heating time were measured in different water-filter ratio. The stability is probably due to the effect of water-filter ratio. This has been further borne out that, water-filter ratio increases, leachable concentration decreases exponentially and tends to a fLxed value.

热害矿井采区大焓差降温系统实验研究

基于热质交换原理与实验理论,设计了大焓差降温除湿实验系统,实验研究不同喷淋压力、气水比、喷水温度下对喷和顺喷的大焓差降温装置降温效果及其热工性能,结果表明大焓差降温装置的适应性强,可满足不同热害程度的采区降温需求。计算了热交换系数和热交换效率,结果表明,对喷方式的热交换效率和热交换系数分别为0.952和0.988,而顺喷方式的热交换效率和热交换系数分别为0.936和0.978。综上,喷嘴对喷方式降温除湿效果稍优于顺喷方式。并由实验数据拟合得到大焓差降温装置的对喷和顺喷的热交换效率系数及热接触系数的经验公式,可更精准的指导热害矿井采区降温工程与大焓差降温装置的设计。

证券交易所一线监管与会计稳健性——基于年报问询函的证据

会计信息缺乏稳健性损害了股东和债权人的利益,如何进行有效监管是学界和实务界共同关注的焦点问题。选取2015—2019年沪深A股上市公司为研究对象,实证分析沪深交易所年报问询函制度对会计稳健性的治理效果,研究发现,年报问询函显著提高了被问询企业的会计稳健性,且当同一年报被问询次数越多、年报问询函问题数量越多、年报问询函需要中介机构发表意见、企业延期回函时,提升作用越大。进一步分析发现,对于负债率较高、内部控制质量较差的企业,年报问询函的监管效果更佳,同时监管依赖于信息环境,当企业信息环境较好时效果更明显;作用机制检验表明,年报问询函通过降低信息不对称、提高独立董事履职独立性和强化投资者关注来提高会计稳健性。结论表明,年报问询函能有效提高上市公司信息质量,发挥一线监管职能,为监管层进一步“加强事中事后监管,完善分级分类监管”及提高上市公司会计稳健性提供了政策思路。

流场板二次流对质子交换膜燃料电池性能影响

电池流道结构对电池性能有直接影响,有必要对电池流道结构进行研究。在质子交换膜燃料电池流道内放置堵块可以增强反应气体的传质进而增强电池性能,但不同堵块对电池性能影响不同。采用数值模拟的方法,建立了三维、稳态的单直流道质子交换膜燃料电池数值模型。对阴极流道内放置不同堵塞率堵块的质子交换膜燃料电池进行研究,重点分析堵块产生的二次流对电池性能的影响。研究发现在流道内放置堵块产生的二次流可以增强电池性能,堵块堵塞率为0.8时电池净功率最大。反应气体在流道内受到堵块扰流作用,在堵块后方产生二次流增强了反应气体传质是电池性能增强的主要原因。

通讯基站分离式热管换热器的传热性能实验研究

通讯基站面临散热不均、散热系统能耗高等问题。分离式热管换热器能替代机房内空调的使用,有效减少基站散热系统能耗。分离式热管换热器传热性能的影响因素有充液率、工质类型和风量等。为了研究不同因素对换热性能的影响,通过理论计算对比分析了理论充液率和实际充液率的差异;搭建实验平台研究了不同充液率下换热器的传热性能变化规律,不同高、中温工质下换热器性能的差异以及室内外风机功率的改变对换热器性能的影响规律。研究发现:使用工质R134a时,最小充液率理论值和实际值的误差为4.74%,换热器最优充液率范围为27.1%~47.9%,且最佳充液率为31.6%,最佳充液率下换热器当量换热系数为909 W/℃;随着充液率的提升,换热器内部相变区域先增大后减小,传热形式由气态工质显热传热为主先变为工质相变潜热传热为主,而后变成液态工质显热传热为主;高温工质不适用于该分离式热管换热器,使用高温工质时,换热器内部无明显相变区域,换热器使用的工质沸点越低,相变区域越大,换热器性能越好,其最佳充液率范围也越大;随着室内、外风机功率增大,换热器性能均先迅速提升而后提升速率减缓,但蒸发器侧由于散热条件较差,提升内风机功率对系统传热性能的提升较提升外风机功率更为显著。

靖西市植烟区土壤交换性钙、镁含量特征及与土壤酸碱的相关性分析

为了明确靖西市植烟区土壤交换性钙、镁含量及其比值的特征,阐明其与土壤酸碱的相关性,以靖西市主要植烟区土壤为研究对象,2022年6月采集植烟区具有代表性的土壤,测定土壤交换性钙、镁含量及计算其钙镁比值,并分析其与土壤酸碱的相关性。结果表明,靖西市主要植烟区土壤交换性钙、镁含量丰富,平均值分别为5 114.59、268.57 mg/kg,土壤交换性钙镁比值大于10,占71.01%。钙镁比值表现为强变异,且交换性钙的变异性大于交换性镁。植烟区土壤pH普遍偏高,pH与土壤交换性钙含量呈极显著正相关,与交换镁含量呈显著负相关,pH对交换性钙含量的影响大于交换性镁,植烟土壤为微碱性时,交换性钙含量处于高及以上水平的占比达100%。综上所述,靖西市主要植烟区土壤交换性钙、镁含量总体处于偏高水平,钙镁比变异强度大,易出现钙、镁平衡失调。因此,今后在生产中需注意酸碱性钙镁肥料的使用以调节土壤酸碱性,并适时培肥土壤,调节土壤钙、镁平衡,提高烤烟产量及品质。

壳管式相变蓄热换热器换热特性的模拟研究

设计了一种以石蜡为相变材料的圆柱型壳管式相变蓄热换热器,以三维单元相变储热模型为研究对象进行了换热数值模拟。分析了相变材料的液相比、温度场、平均温度及换热介质出口温度的变化规律,研究了该壳管式相变蓄热换热器在蓄、放热阶段的换热特性。结果表明:液相石蜡的自然对流会增强相变材料与换热介质之间的换热,并加快石蜡的熔化和凝固速率;蓄热阶段液相比达到18.6%后,自然对流换热的影响逐渐明显;放热阶段初期,液相比在80 s内下降了63%,固态石蜡层完全包裹传热管束前的自然对流换热最强,之后逐渐减弱。