乳成分对凝固型酸乳贮藏品质的影响

鲜乳的乳成分随季节、温度、挤乳时间及次数变化明显,导致用其直接加工的酸乳品质差异较大,因此,本实验研究了不同乳蛋白、乳脂肪和乳糖添加量对酸乳贮藏期间酸度和持水性的影响.结果表明:酸乳贮藏持水性随乳蛋白、乳脂肪和乳糖添加量的升高而明显增强;酸度随乳蛋白添加量的增加明显上升,而脂肪和乳糖添加量对凝固型酸乳贮藏酸度无明显影响.     

Effects of structure design on resilience and acoustic absorption properties of porous flexible-foam based perforated composites

In this paper, perforated composite panel was combined with porous and resonance structures to investigate the influence on acoustic absorption and resilient properties. The perforated composite panel was fabricated based on highdensity flexible-foam via perforating and reinforcing with laminated hybrid nonwoven fabric. Effect of aperture size (AS) (ranging from 3 mm to 6 mm), perforation ratio (PR) (5 %, 10 %, 15 % and 20 %) and perforation depth (PD) (25 %, 50 %, 75 % and 100 %) on the compressive hardness, rebound resilience and acoustic absorption properties was explored. Multiply hybrid nonwoven fabric which was fabricated with low-melting point polyester (LMPET), flame-retardant polyester (FRPET) and recycled Kevlar fibers was utilized to reinforce the flexible composites and improve the acoustic property. Nonwoven that was fabricated with entangled LMPET fibers had porous structures which could reinforce the flexible foam and enhance the acoustic absorption properties. The result revealed that the continuity and supporting of porous flexible foam had directly influence the compressive hardness. The maximum hardness of the flexible-foam based perforated composites reached 420 N. The rebound resilience result showed that the sample had high resilient structure and the resilience was up to 48 %. The perforated flexible composites plate (PFP) with 4 mm-AS performed the highest acoustic absorption coefficient at 0.9. The acoustic absorption coefficient was higher than 0.8 in the frequency range from 800 to 1600 Hz and 1600 to 2400 Hz when perforated composites had 4 mm-AS at 5 % and 10 % perforation ratio. With the increase in perforation ratio, absorption peak moved from 3200 Hz to 4000 Hz. Hybrid nonwoven laminated layer help to broaden the frequency range of acoustic absorption of perforated high-density flexible foam based composites panel. Acoustic absorption coefficient was higher than 0.4 when frequency ranging from 900 Hz to 4000 Hz.     

Piscidin is Highly Active against Carbapenem-Resistant Acinetobacter baumannii and NDM-1-Producing Klebsiella pneumonia in a Systemic Septicaemia Infection Mouse Model

This study was designed to investigate the antimicrobial activity of two synthetic antimicrobial peptides from an aquatic organism, tilapia piscidin 3 (TP3) and tilapia piscidin 4 (TP4), in vitro and in a murine sepsis model, as compared with ampicillin, tigecycline, and imipenem. Mice were infected with (NDM-1)-producing K. pneumonia and multi-drug resistant Acinetobacter baumannii, and subsequently treated with TP3, TP4, or antibiotics for different periods of time (up to 168 h). Mouse survival and bacterial colony forming units (CFU) in various organs were measured after each treatment. Toxicity was determined based on observation of behavior and measurement of biochemical parameters. TP3 and TP4 exhibited strong activity against K. pneumonia and A. baumannii in vitro. Administration of TP3 (150 μg/mouse) or TP4 (50 μg/mouse) 30 min after infection with K. pneumonia or A. baumannii significantly increased survival in mice. TP4 was more effective than tigecycline at reducing CFU counts in several organs. TP3 and TP4 were shown to be non-toxic, and did not affect mouse behavior. TP3 and TP4 are able at potentiate anti-Acinetobacter baumannii or anti-Klebsiella pneumonia drug activity, reduce bacterial load, and prevent drug resistance, indicating their potential for use in combating multidrug-resistant bacteria.     

Anti-Obese Effect of Glucosamine and Chitosan Oligosaccharide in High-Fat Diet-Induced Obese Rats

Objective: This study is to evaluate the anti-obese effects of glucosamine (GLC) and chitosan oligosaccharide (COS) on high-fat diet-induced obese rats. Methods: The rats were randomly divided into twelve groups: a normal diet group (NF), a high-fat diet group (HF), Orlistat group, GLC high-, middle-, and low-dose groups (GLC-H, GLC-M, GLC-L), COS1 (COS, number-average molecular weight ≤1000) high-, middle-, and low-dose groups (COS1-H, COS1-M, COS1-L), and COS2 (COS, number-average molecular weight ≤3000) high-, middle-, and low-dose groups (COS2-H, COS2-M, COS2-L). All groups received oral treatment by gavage once daily for a period of six weeks. Results: Rats fed with COS1 gained the least weight among all the groups (P < 0.01), and these rats lost more weight than those treated with Orlistat. In addition to the COS2-H and Orlistat groups, the serum total cholesterol (CHO) and low-density lipoprotein cholesterol (LDL-C) levels were significantly reduced in all treatment groups compared to the HF group (P < 0.01). The various doses of GLC, COS1 and COS2 reduced the expression levels of PPARγ and LXRα mRNA in the white adipose tissue. Conclusions: The results above demonstrated that GLC, COS1, and COS2 improved dyslipidemia and prevented body weight gains by inhibiting the adipocyte differentiation in obese rats induced by a high-fat diet. Thus, these agents may potentially be used to treat obesity.     

酸化剂对碱性土壤和水体的改良机制及其效果

本文主要概述了碱性土壤和水体的形成原因、危害以及酸化剂的种类和特点,总结了酸化剂对碱性土壤和水体的改良机制与应用,为碱性土壤和水体的改良提供参考。     

虾类肌肉白浊病病原和病理的研究进展

本文针对虾类肌肉白浊病易感染的罗氏沼虾、凡纳滨对虾、中国对虾进行了分析。从病毒、细菌、寄生虫和环境因素方面,总结了近十几年来虾类肌肉白浊病的病原和病理特征。归纳了虾类肌肉白浊病的流行病学、检测方法及综合防治。     

稻蝗肠道真菌的除草活性筛选及菌株DH03的鉴定

利用涂布平板法从中华稻蝗肠道中分离得到6株真菌,活性筛选试验表明菌株DH03具有较好的除草活性。当供试质量浓度为100 μg/mL时,该菌株发酵液的乙酸乙酯提取物对稗草和反枝苋根生长的抑制率均大于80%,比阳性对照2,4-二氯苯氧乙酸的活性好;进一步研究表明发酵液活性物质主要集中在中等极性部分;该菌株的发酵液对盆栽稗草幼苗生长表现出较强的抑制作用,当喷施发酵液原液时,稗草的受害率和均株高分别为36.1%和9.78 cm。经形态学观察和ITS序列分析确定该菌株为Cladosporium oxysporum。DH03作为微生物源除草剂值得进一步研究。     

齿墩状内消能工的消能及压力特性

输水管道或泄洪洞常见的内消能方式为孔板和洞塞,结合明渠水流中的消能工形式提出了齿墩状内消能工,并通过物理模型试验对不同面积收缩比的齿墩状内消能工进行了研究,分析了它们的过流能力、消能率、压强沿程变化及脉动压强特性.结果表明:齿墩状内消能工的过流能力主要是由消能工的体型及尺寸决定的,其面积收缩比越大,消能率越低,过流能力就越强;齿墩状内消能工的时均压强在收缩段骤降,在其后部逐渐上升,而后恢复至稳定,其恢复长度基本相同;齿墩状内消能工的脉动压强最大点均出现在收缩段后1倍圆管直径范围内,随后迅速减小,逐渐趋于平稳;面积收缩比为0.471 2的齿墩状消能工的脉动强度最小,因而其抗空化性能优于其他情况,且脉动压强最大点的压强概率密度分布接近正态分布.     

木霉制剂对茉莉白绢病和土壤微生物数量的影响

采用稀释分离法研究了木霉菌在土壤中的定殖动态以及木霉制剂对土壤微生物数量的影响情况,田间测定了木霉制剂对茉莉白绢病的防治效果。结果表明,在含有基质的情况下,木霉菌在土壤中的存活数量呈先上升后下降的趋势;并且木霉菌在灭菌土中的存活量明显高于自然土。茉莉种植园施入木霉制剂后,茉莉根围土壤中细菌和真菌的数量显著提高,白绢病的发病率明显降低;处理区的最高防效达71.07%。     

作物残茬与生物篱组合对减轻土壤风蚀的作用

为了探究中国北方农牧交错带冬春风蚀季节生物篱与作物残茬组合对间作裸露秋翻地的防护作用,采用风蚀圈和野外移动式风洞试验的方法对研究区土壤风蚀情况进行监测,利用PC-3型自动气象站进行风速测定。结果表明,油葵秆生物篱减小了间作裸地近地面风速,提高了地表粗糙度;从防风蚀效果看草谷子茬优于油葵秆生物篱;在距油葵秆生物篱或草谷子茬下风向裸地不同位置处,土壤风蚀量基本呈先增加后减小的单峰曲线变化趋势,在4 m左右土壤风蚀量最大,在篱和茬的双重保护下,距茬5 m处发生了风积现象;土壤风蚀量降低率基本呈“V”字型分布;土壤风蚀模数随风速增大而增加,在生物篱的保护下5～15 m/s风速时土壤风蚀降低率为5.03%～20.53%。因此,油葵秆生物篱具有防风蚀作用,而且与草谷子残茬组合对间作裸地会起到更好的固土防蚀作用。