冰水混合间接换热系统中换热器参数试验

利用北方地区冬冷夏热的特点,冬季冻冰蓄冷,夏季利用。采用间接换热冷量交换系统,有利于低碳节能和保护环境。该文对系统中换热器的参数进行了优化试验。以热交换器中的风速、流量、迎风面积、热管长度为影响因素,以热交换器的换热效率为目标,得到换热效率84%以上的较佳参数组合为风速2.54～2.93 m/s,流量0.72～0.80 m3/h,迎风面积11.93～13.51 dm2,热管有效长度7.99～9.95 m。该研究为利用自然冷资源间接换热冷量交换系统中热交换器的设计和应用提供依据。     

微型茯砖茶发花技术研究

对黑毛茶接种冠突散囊菌,压制为质量为5 g左右的圆柱形的茯砖茶,再发酵制作微型茯茶。采用单因素试验和正交试验,通过研究茶叶含水量、蒸制时间、渥堆温度及渥堆时间,筛选出合适的工艺条件,并确定制作微型茯茶的最佳工艺参数。结果表明:影响微型茯茶品质的环境因子依次为:含水率>渥堆温度>蒸制时间>渥堆时间,最优水平为含水率26%,蒸制时间10 min,渥堆温度70℃,渥堆时间2.0 h,在此条件下其发酵的茶叶汤色红艳透明、香气浓郁、滋味甜香醇和。     

Phenotypic and genotypic characterization of β-lactam resistance in Klebsiella pneumoniae isolated from swine

Little is known about the antimicrobial resistance mechanisms in Klebsiella pneumoniae from swine in China. Thus, this paper aims to demonstrate the β-lactam resistance phenotypes and genotypes of K. pneumoniae isolates from swine in southwestern China, detect possible new β-lactamase variants, and determine whether or not the variants differ in their antibiotic resistance. Isolates from 58 unrelated diseased swine were collected from 61 pig farms in southwestern China from 2007 to 2009. Among the 58 isolates, 75.8-100% were resistant to β-lactam, 62.0-68.97% to fluoroquinolone, 44.8-46.55% to aminoglycoside, and 8.62-17.24% to β-lactam inhibitors. PCR amplification and DNA sequencing showed that bla(TEM-1) was detected in 100% (n=58) of the isolates, bla(SHV) in 82.76% (n=48), bla(CTX-M) in 39.66% (n=23), and bla(OKP) in 17.24% (n=10). The bla(SHV) types included bla(SHV-1), bla(SHV-11), bla(SHV-12), and bla(SHV-27). None of the isolates harbored bla(KPC), bla(LEN), or bla(GES) gene. Four novel variants (bla(OKP-A-13), bla(OKP-A-14), bla(OKP-A-15), and bla(OKP-A-16)) were identified among the 10 OKP β-lactamase-producing K. pneumoniae isolates resistant to ampicillin, amoxicillin, oxacillin, cefalexin, and cefadroxil. Plasmid analysis and PCR amplification indicated that bla(TEM-1) genes were detected in the total plasmid. Molecular typing by pulsed-field gel electrophoresis revealed the presence of 10 distinct pulsotypes of OKP producer isolates. Plasmid DNA digested with XbaI yielded two to six bands of ca. 0.15-30 kb. Transformants of the 10 OKP producer isolates showed no differences in their antibiotic susceptibility, except for the pulsotype B transformant, which carried bla(CTX-M). In China, β-lactam resistance appeared to be common among K. pneumoniae isolates from swine, suggesting that K. pneumoniae may be a reservoir for the dissemination of β-lactam resistance among Chinese pig farms.     

澳洲坚果物理参数试验研究

对澳洲坚果千粒质量、含水率、果实及果仁三径尺寸、壳厚度、壳仁间隙和出仁率等基本物理参数进行了测定.结果表明:在相同条件下,坚果的外形尺寸呈正态分布,63%的果实分布在24~26mm范围内;不同位置果壳厚度差异较大,果壳底部最厚,中部最薄;壳仁间隙为1.20mm.     

轿车性能分析与优化研究

首先对发动机的外特性和万有特性进行研究并建立相应数学模型.其次结合汽车相关理论,阐述计算整车动力性和经济性的一般方法.以动力性和经济模拟计算为基础,根据变速器传动比优化的思路和方法,结合某款实车进行速比优化的工作.模拟计算结果表明,经过优化整车的动力性和经济性都有一定程度的提高.     

Chemical characterization of a procyanidin-rich extract from sorghum bran and its effect on oxidative stress and tumor inhibition in vivo

The present study was to characterize a procyanidin-rich extract (PARE) from sorghum ( Sorghum bicolor (L.) Moench) bran and assess its biological activities. The procyanidin oligomers were separated and identified by normal-phase HPLC equipped with fluorescence (FLD) and mass spectrometry (MS) detectors. In addition, the effects of PARE on oxidative stress in mice induced by D-galactose as well as tumor inhibition in C57BL/6J mice bearing Lewis lung cancer were investigated. Administration of D-galactose significantly (p < 0.05) lowered the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). This was accompanied by a significant (p < 0.05) increase in malondialdehyde (MDA) levels in both liver and serum. Administration of PARE (150 mg/kg) significantly (p < 0.05) reversed the d-galactose-induced oxidative stress by enhancing the activities of antioxidant enzymes. Furthermore, PARE administration inhibited tumor growth and metastasis formation by suppressing vascular endothelial growth factor (VEGF) production. The results suggested that PARE had antioxidant and antitumor activities.     

双台河口自然保护区丹顶鹤春季迁徙停歇地生境选择

2009年3月,采用样线法、样点法对辽宁双台河口自然保护区内迁徙停歇的丹顶鹤进行观察监测,确认并用GPS定位其停歇地;通过样方法、因子测定法进行对其停歇生境进行实地测量与分析。结果表明：（1）芦苇沼泽是丹顶鹤主选的停歇生境,占到96.4%;（2）丹顶鹤停歇地与火烧地的距离小于25 m,在火烧地边缘活动,或者停在火烧地中;（3）丹顶鹤一般会选择油井距离大于1 km处作为停歇地（100%）;（4）丹顶鹤距明水面的距离较近,便于获取食物与水等;（5）频繁区对丹顶鹤影响明显。影响丹顶鹤的停歇地选择的因素既有自然因素如植被环境和明水面,也有人为因素如火烧和油井乃至道路。针对不同因素的空间分布,丹顶鹤的迁徙停歇地选择也具有一定的选择性。     

附红细胞体病研究进展

根据国内外文献及临床实践,综述了附红细胞体病的病原学、流行病学、发病机理、临床症状、病理变化、诊断和防治等方面研究现状,为今后的研究提供参考。     

Molecular cloning and expression analysis of the gene encoding sedoheptulose-1, 7-bisphosphatase from Cucumis sativus

Sedoheptulose-1, 7-bisphosphatase (SBPase; EC 3.1.3.37) is a key enzyme in the photosynthetic carbon reduction cycle (Calvin cycle). In the present study, a full-length cDNA encoding SBPase (designated as CsSBP, GenBank accession no. FJ911553) was isolated from cucumber (Cucumis sativus L. cv. ‘Jinyou 3’) grown in solar-greenhouse by RT-PCR and RACE. The cDNA contained 1452 nucleotides with a complete open reading frame (ORF) of 1167 nucleotides, which was deduced for encoding a peptide of 388 amino acids whose molecular mass was inferred to be 42 kDa with its isoelectric point at 6.17. Sequence comparison analysis showed that the deduced amino acid of SBPase from cucumber leaves had high homology to that from other species. Expression analysis by real-time PCR and Western blot revealed that CsSBP mRNA and protein was most abundant in leaves, detectable in stems and fruits, but invisible in roots. A similar difference was found in SBPase activity among leaves, stems, fruits and roots. CsSBP expression at the mRNA and protein level was the highest in mid-position leaves (4th–8th apical expanded leaves) of plants, medium in base position leaves (12th), and the lowest in upper position leaves (1st). However, SBPase activity decreased successively as leaf position declined. The net photosynthetic rate (Pn) of mid-position leaves was also found to be the highest, but that of base-position leaves was lower than upper-position leaves. The diurnal variations of gene expression and SBPase activity in optimal functional leaf (6th leaf) was a single-peak pattern curve, which was similar to that of Pn, and the peak appeared at 12:00. These data indicate that CsSBP expresses only in green tissues of cucumber plants and there are close positive correlations between SBPase activity and gene expression at the mRNA and protein levels, and between SBPase activity and Pn in leaves of cucumber plants.