Estimation of left ventricular filling pressure by Doppler echocardiography in dogs with pacing-induced heart failure

BACKGROUND: Congestive heart failure (CHF) is a common clinical syndrome characterized by elevated filling pressure. HYPOTHESIS: Doppler echocardiographic (DE) variables of left ventricular (LV) filling can predict a decline of LV end-diastolic pressure (LVEDP) induced by acute preload reduction in dogs with compensated CHF. ANIMALS: Five male hound dogs. METHODS: Dogs previously instrumented with a transvenous cardiac pacemaker and a LV pressure gauge were paced at 160-180 bpm to induce mild CHF characterized by LVEDP > 20 mmHg. LVEDP and 9 DE variables of LV filling derived from diastolic time intervals, transmitral and pulmonary venous flow, and tissue Doppler imaging were measured simultaneously at baseline and 30, 60, 120, and 240 minutes after furosemide (4 mg/kg, IV) or placebo (0.9% saline, IV). Repeated measures analysis of variance and correlation analysis were used to determine the association between the decline of LVEDP after furosemide and DE measures of LV filling pressure (LVFP). RESULTS: Furosemide but not placebo decreased LVEDP (P < .001). The ratio of early transmitral flow velocity to LV isovolumic relaxation time (E : IVRT) predicted LVEDP best (R(2)= .50; P < .001). Correlations were also found between LVEDP and IVRT, E, ratio between E and late diastolic transmitral flow velocity (E : A), and early diastolic velocity of the mitral annulus (Ea). The ratio of E to Ea (E : Ea) was not useful in the prediction of LVEDP in this model. CONCLUSION AND CLINICAL IMPORTANCE: E : IVRT can be used to predict LVFP in dogs with mild left-sided CHF induced by rapid pacing.     

Use of continuous positive airway pressure in the acute management of laryngeal paralysis in a cat

Continuous positive airway pressure (CPAP) has been is used widely in humans to manage obstructive sleep apnoea syndrome, but it has not been widely used in animals. A brachycephalic cat, with previously undiagnosed laryngeal paralysis, that developed acute upper respiratory tract obstruction on recovery from anaesthesia, is presented. The condition was managed by CPAP, delivered via a facial mask.     

低排泄氮量的鹌鹑改良选育

选用日本鹌鹑N、B（Normal、Brown）品系和杂种群（BN）,共进行8个世代（6～20周龄）的选育试验,各品系采用单因子试验设计,在CP18％日粮条件下分选育组、非选育组以及对照组（CP24％）,N、B基础群中选留15种家系,以采食量为主选性状,以产蛋率和排泄氮量为辅选性状作为选育指标进行试验。结果表明：随着世代数的增加选育组和对照组的适应力均有显著升高（P〈0．05）,N品系的各世代遗传改进量为0．26;另外,世代间产蛋率有增高的倾向,选育组平均累积产蛋率与非选育组较显著升高（P〈0．05）,特别是选育组各世代遗传改良极为显著（P-〈0．01）。各世代间采食量无显著差异,同世代各品系间选育组N、B采食量均高于非选育组,但显著低于对照组（P〈0．05）。选育组排泄氮量和血清中尿酸含量在改良2世代后明显低于非选育组和对照组（P〈O．05）,排泄氮量分别降低7％～15％。综上所述,通过选育N、B新品系,能够改善产蛋性能,且显著降低排泄氮量,在BN杂种群中效果更明显。     

应用变压差技术的气道稳流试验研究

根据发动机气道流动特性,应用变压差技术测量了6135型柴油机缸盖进气道的流动特性。试验全过程只需确定气门最大升程时,模拟气缸与环境气压的初始压差满足流经气道内的空气为充分发展的湍流条件,就可采集对应于各气门升程下的流量和涡流角动量等试验参数,并用Ricardo和FEV方法计算平均流量系数和涡流比,其计算值与定压差试验结果基本相同。此方法操作简单,易于实现气道稳流试验的全自动化,可提高生产线上批量缸盖检测效率。     

Differential tolerance of weedy red rice (Oryza sativa L.) from Arkansas, USA to glyphosate

Red rice (Oryza sativa L.), a weedy relative of cultivated rice (O. sativa), is a troublesome weed in rice in the southern United States. It is also very problematic in other world regions where rice is grown. There are many types of red rice. Some have white pericarp. In this paper, the term ‘red rice’ will be used to refer to the weedy types that occur in this region of the southern USA. Because of the great diversity in morphology and phenology of red rice populations in the USA, we hypothesized that these have differential tolerance to glyphosate. Red rice is subjected to selection pressure by glyphosate, which is the principal herbicide used in glyphosate-resistant soybean planted after rice. Two hundred-fifteen red rice accessions were collected in Arkansas, USA between 2002 and 2003 and evaluated for glyphosate tolerance between 2003 and 2006. The commercial dose of glyphosate controlled red rice accessions 81-100% regardless of application timing, by 30 d after treatment. The number of survivors that produced seeds and the seeds produced per survivor differed between accessions. Application of the full dose at the tillering stage was more effective than at the 3- to 4-leaf stages. At half the field dose, 40 to 54% of survivors produced seed, with germination capacity of 30-100%. The lowest dose of glyphosate, 225 g a.e. ha⁻¹, resulted in the widest range of control ratings from 30 to 100%. The red rice accessions differentiated into six tolerance categories. A tolerance map was generated and will be used in educating growers about the proper use of glyphosate for red rice management.     

华北落叶松液流速率的优势度差异及其对林分蒸腾估计的影响

将实测的杨树液流速率和林木边材厚度(或胸径)经尺度扩展得到林分蒸腾,已成为常用的野外测定方法,但此法没有考虑其他树形因子的影响,当林分密度大、光竞争激烈时,会导致蒸腾估计误差偏大。为认识主要树形因子对液流速率的影响,并为改进样树液流向林分蒸腾的尺度扩展方法提供依据,在六盘山北侧半干旱区华北落叶松人工林内,利用热扩散探针对5株不同优势度样树的液流速率进行了连续观测,研究了生长季中期(叶面积指数达到峰值并保持稳定)不同土壤水分条件下不同优势度树木的液流速率差异。结果表明:优势度越大的树木,其液流在日内的启动越早,结束越晚,到达峰值越早,峰值也越大;日均液流速率明显比优势度小的树木高;液流速率对太阳辐射和饱和水汽压差瞬时变化的响应敏感性比优势度小的树木高,而对土壤水分条件的响应敏感性则弱于后者,但整体上对环境条件的响应趋势一致,不同优势度树木间液流速率的相对差异比较稳定。相关分析表明:液流速率与优势度(或相对树高)、树高呈极显著正相关,与冠长、胸径显著正相关,而与冠幅、边材面积正相关但不显著。利用拟合的优势度与液流速率之间的线性关系(R²=0.95)计算了样地内所有树木的液流速率及其平均值,即林分平均液流速率,该值比常用方法计算结果低16%。建议今后在利用样树液流速率测定结果进行尺度扩展计算林分液流速率和蒸腾时,增加考虑优势度等主要树形因子的影响。     

常山胡柚研究现状及存在的问题

综述了常山胡柚的研究现状,研究中的一些热点问题、难点问题及其趋势。常山胡柚是浙江省常山县原产的柑桔地方品种,属亚热带常绿果树。1991年被正式定名而成为中国柑桔属植物的一个新种,并先后对其生物学特性、良种选育、栽培管理与丰产经营技术及其果实营养、采后生理、贮藏保鲜与加工利用等方面进行了较系统的研究和探索。提出今后在常山胡柚的分子鉴定、果实的生长发育规律与成熟机理、果实的贮藏保鲜、深加工及综合利用等方面需深入研究,以真正提高常山胡柚的产量和品质。     

海洋下沉颗粒相关微生物群落的相互作用和演替

海洋表层透光区通过光合作用产生的有机物主要以颗粒有机物（POM）的形式输送至深海。异养微生物以其对于POM的分解作用机制不同而分为两类：颗粒附着的附生菌（particle-attached mode,PAM）和自由营生的自由菌（free-living mode mode,FLM）,是介导海洋中颗粒有机碳（POC）和溶解有机碳（DOC）循环的主要参与者。然而,目前对PAM和FLM的微生物群落组成和生物地球化学功能的理解大多局限于固定深度原位海水的探讨,或者在实验室模拟中以某一固定压力直接富集微生物。本次研究采用马里亚纳海沟“挑战者深渊”50米深表层海水,并接种13C标记和非标记的POM,设置0.1、10、30和60 MPa四个压力梯度,以逐渐加压的方式模拟颗粒物沉降过程进行富集培养,探讨了在模拟海洋有机颗粒物下沉过程中两种不同形式微生物的演替和相互作用的动态演变。结合稳定同位素探针技术（DNA-SIP）和16S rRNA基因的高通量测序,结果表明19个活性OTUs被13C所标记,主要隶属于α-Proteobacteria以及γ-Proteobacteria。在不同压力梯度下,附生菌或自由菌中活性OTUs的类型和丰度有显著差异。此外,微生物网络结构（network）的相互作用在高压下呈正向为主,表明着深海中存在着激烈的物种竞争,微生物群落在高压下表现出明显的分离和模块化,具体表现为network拓扑特征系数的弹性和稳定性。模拟颗粒沉降高压培养结果重点揭示了在沉降过程中,静水压力对海洋中下降颗粒物降解相关的微生物的群落结构和功能的调控作用。     

基于变压射流燃烧技术的生物质炉具设计

生物质炉具是通过生物质燃烧提供热量的环保型炉具,具有高效、环保、热效率高、烟尘排放低等优点,被广泛应用于民用热水、建筑采暖和工业热力等领域中,在我国有着悠久的历史和广泛的基础。然而,市面上现存的生物质炉具由于技术限制,在燃烧过程中难以保证生物质燃料充分燃烧,存在锅炉热效率低及污染环境问题;故本文设计了一种基于变压射流燃烧技术的生物质成型燃烧炉具,即在燃烧过程中,2个进气机构所形成的一次风和二次风在炉体中以自旋、整体旋或者二者叠加的方式存在,通过改变两次风的风量比例、进气位置、充气角度,在炉具内形成不同的风压射流,以强化热质传递,确保燃尽效果,在燃烧过程中有效控制氮氧化物的生成与排放。燃料燃烧试验结果表明：玉米秸秆燃烧热效率为85.97%,底灰结渣率为3.42%,生物质颗粒燃烧较充分;SO2排放量为18.34mg/m3,NOx排放量为91.45mg/m3,CO体积分数为0.092%,污染物排放量符合国家标准;锅炉具有较好的稳定性,满足设计要求。     

超高压和热灭菌对鲜榨菠萝汁品质影响的比较

对比分析了超高压（UHP,ultra-high pressure）及热处理在达到商业杀菌要求的基础上对菠萝原汁感官品质、营养成分及理化性质的影响。试验结果表明,随着压力值（300～500 MPa）的上升菌落总数逐渐减少,超高压处理（400 MPa,26℃,10 min）及热处理（85℃,5 min）条件下均可达商业无菌;上述2种处理条件处理后菠萝原汁pH值、总酸、总糖、可溶性固形物含量与对照样差异不显著（P＞0.05）;超高压处理样品能较好地保持体系的均匀稳定性;超高压处理样品与热处理样品的L*、a*、b*值与对照样相比变化均显著（P＜0.05）,但超高压处理样品更好地保持了原有色泽;超高压处理样品的还原型维生素C保留率达94.92%,远高于热处理;感官分析通过定量描述分析法对不同处理方式处理后的样品进行分析评定,结果表明,超高压处理样品在色、香、味等方面都接近对照样。因此,超高压技术不仅具有较好的杀菌效果,而且最大限度地保证了菠萝汁的品质。