4种相思树种的解剖特征与木材材性比较分析

本文运用对比分析的方法对4种相思木材的解剖特征、纤维形态等进行了详细的测量、观察与分析,对4种木材的基本密度、气干密度、干缩系数、抗弯强度、抗弯弹性模量、冲击韧性等进行了对比研究。结果表明,厚荚相思的纤维平均长度最大为1179.6μm,而马占相思的导管平均长度333.1μm为最大。4种相思木材的纤维微观形态可以满足制浆造纸的要求,可以作为纸浆材使用。卷荚相思的气干密度和基本密度值均为最大,分别为721 kg/m3和617 kg/m3。马占相思的干缩和湿胀系数基本上都是最小的,所以马占相思的尺寸稳定性最好,而卷荚相思的各项力学指标都是最好的,所以卷荚相思的力学性能最好。     

彩色棉纤维品质的杂种优势分析

采用NCⅡ设计,以3个白色棉为母本,3个绿色棉为父本,配制绿色杂交组合;以2个白色棉为母本,以4个棕色棉为父本,配制棕色杂交组合。纤维品质杂种优势和配合力方差分析表明:绿色杂种(F1)纤维品质的超白色棉亲本优势、中亲优势、超彩色棉亲本优势和竞争优势,2.5%跨长分别为0.91%、6.53%、13.02%和1.21%,比强度分别为-5.77%、15.63%、49.7%和1.02%,马克隆值分别为-14.6%、9.31%、52.51%和-23.61%。棕色杂种(F1)纤维品质的超白色棉亲本优势、中亲优势、超彩色棉亲本优势和竞争优势,2.5%跨长分别为-3.09%、1.71%、7.12%和-5.59%,比强度分别为-6.99%、-0.06%、9.55%和-4.05%,马克隆分别为-8.67%、-3.15%、4.49%和-18.37%。绿色纤维2.5%跨长的加性方差和显性方差分别占表性方差的56.18%和31.32%,达显著;比强度以显性方差为主,占表性方差的59.53%,马克隆值的显性方差占表性方差的39.22%,达显著;棕色纤维绿色纤维2.5%跨长以加性方差为主,占表性方差的68.59%,达极显著;比强度加性方差占表性方差的37.77%,达显著,马克隆值的加性方差和显性方差分别占表性方差的54.76%和34.69%,均达显著。     

Fibre supplementation to pre-weaning piglet diets did not improve the resilience towards a post-weaning enterotoxigenic E. coli challenge

Dietary fibre (DF) is implicated in gastrointestinal health of weaned piglets, either through its physiochemical properties, through modulation of gut microbiota and (or) improved gut integrity. We aimed to study the effect of DF enriched supplemental diets fed to suckling piglets (‘creep feed’) on health and performance after weaning when challenged with an enterotoxigenic E. coli (ETEC). Seventy-two piglets originating from 28 litters had been fed four creep diets, that is a low-fibre control (CON); a diet containing 2% long-chain arabinoxylans from wheat (lc-AXOS) or 5% purified cellulose (CELL) or a diet containing the high fermentable and the low-fermentable fibre source (i.e. 2% lc-AXOS and 5% CELL). Upon weaning, piglets were individually housed and all fed the same diet. On days 7, 8 and 9, animals received an oral dose of ETEC (5 ml containing 10⁷ to 10⁸ CFU/ml). Besides growth performance, faecal and skin scores were recorded daily. Gut permeability was assessed by urinary excretion of Co-EDTA prior and post-ETEC challenge. Repeated measures in time were statistically evaluated with generalized linear mixed models. We used a binominal distribution for evaluating the faecal and skin scores. Feed intake and body weight gain did not differ between treatments (p > .05). Piglets on CELL decreased gain:feed ratio in week 2 + 3 week compared to CON (p = .035). Prior to ETEC challenge, gut permeability tended to increase for lc-AXOS (p = .092). Moreover, lc-AXOS as main effect increased intestinal permeability before ETEC challenge (p = .013), whereas the low-fermentable fibre lead to elevated intestinal permeability after ETEC challenge (p = .014). The incidence of diarrhoea was higher for lc-AXOS + CELL compared with lc-AXOS (p = .036), while skin condition was unaffected. In conclusion, neither the high fermentable nor the low-fermentable fibre source improved post-weaning growth or gastrointestinal health of the piglets.     

日粮添加尿素对瘤胃上皮细胞增殖、凋亡以及吸收转运能力的影响

本研究探讨了在日粮中添加尿素替代部分豆粕对山羊瘤胃发酵、上皮细胞增殖、凋亡和吸收转运能力的影响。将18 只波杂山羊随机分为3 组（n=6）,分别饲喂3 种日粮：LC组（纯粗料）、MC组（30%精料）以及Urea组（1%DM缓释尿素替代部分豆粕+30%精料）。饲喂Urea组和MC组的山羊瘤胃中短链脂肪酸（SCFA）浓度、pH值均显著高于LC组,而该两组之间无显著差异;但Urea组在MC组的基础上进一步显著提高了瘤胃NH₃和血浆尿素氮（BUN）浓度。因此日粮添加尿素对于瘤胃上皮中受瘤胃SCFA浓度、pH值调节的上皮生长、细胞周期、增殖凋亡相关基因和SCFA转运载体mRNA表达的影响与MC组相似,但对受瘤胃NH₃调节的尿素转运、细胞内pH（pHi）调节相关蛋白mRNA表达则有显著的抑制效果,即显著高于LC组,但低于MC组。     

舍饲、放牧对滩羊股二头肌纤维特性及宰后成熟过程中蛋白降解的影响

试验旨在研究舍饲（concentrate feeding,CF）、放牧（pasture feeding,PF）对滩羊股二头肌肉品质、肌纤维特性、宰后成熟过程中超微结构及蛋白降解变化的影响。选取体重接近的4~5月龄滩羊公羔28只,随机分为2组,每组14个重复,每个重复1只羊,分别以舍饲、放牧方式饲养,试验期60 d。试验结束后采集股二头肌作为试验样品,并对其肉质性状、肌纤维特性及宰后成熟过程中超微结构与蛋白降解各项指标进行测定分析。结果显示,放牧组羊肉剪切力、硬度和内聚性均显著高于舍饲组（P<0.05）,弹性则显著低于舍饲组（P<0.05）;放牧组羊肉肌纤维密度和Ⅱ型肌纤维的数量比例均显著低于舍饲组（P<0.05）,Ⅰ型肌纤维的直径、横截面积和数量比例均显著高于舍饲组（P<0.05）。在宰后成熟过程中,舍饲组羊肉肌浆蛋白溶解度显著高于放牧组（P<0.05）;两组肌原纤维蛋白溶解度在宰后24 h至最低后逐渐回升,但各时间点差异均不显著（P>0.05）;肌原纤维小片化指数显著上升后趋于平稳,舍饲组增加率（50.97%）高于放牧组（41.94%）;超微结构显示,宰后肌肉肌原纤维结构松弛、裂解,Z线发生降解,肌原纤维小片化出现,舍饲组肌原纤维结构破坏程度比放牧组更严重。舍饲组肌浆蛋白变性程度小,宰后降解速率较慢,而肌原纤维蛋白降解较明显,降解产生的小分子蛋白量高于放牧组。综上所述,饲养方式改变了滩羊股二头肌纤维特性,并对宰后成熟过程中肌肉超微结构及蛋白降解产生影响,舍饲饲养使得股二头肌纤维密度增加,肌纤维直径与横截面积减小,并降低了肌肉剪切力;此外,由于Ⅱ型肌纤维比例的增加,舍饲饲养提高了肌肉宰后肌原纤维小片化指数增长率、肌浆蛋白溶解度和蛋白降解速率,使宰后成熟过程加快,改善了股二头肌肉嫩度。     

猪肌纤维性状形成和肌内脂肪沉积的遗传机制

近年来,通过改变肌纤维性状和肌内脂肪含量改善猪肌肉品质成为科学家们研究的热点。肌纤维性状形成和肌内脂肪沉积是内因与外因共同作用的结果。作者对猪肌纤维性状形成和和肌内脂肪沉积的遗传机制进行了综述,以期寻求调控及改善猪肌肉品质的方法。猪肌纤维性状形成和肌内脂肪沉积的遗传机制非常复杂,受基因、转录因子及信号通路的复杂网络调控。猪肌纤维的生长发育主要受生肌决定因子（myogenic determinant,MyoD）基因家族和肌肉生长抑制素（myostatin,MSTN）基因一正一负协同调控。能量感应网络AMPK/SIRT1/PGC-1α在猪肌纤维类型转化中起重要作用。脂肪沉积相关基因的表达量与猪肌内脂肪沉积有密切关系。随着分子生物技术的不断发展,许多与肌纤维性状形成和肌内脂肪沉积的相关基因已被鉴定出来,有助于进一步揭示猪肌纤维性状形成和肌内脂肪沉积的遗传机制。     

非木材纤维纸浆中杂细胞的沼气发酵

采用L9(34)正交试验法,对影响杂细胞沼气发酵的基质浓度、发酵温度、添加剂三因素进行批量发酵.结果表明,基质浓度对发酵效果影响最大,其次是添加剂.发酵温度对发酵周期影响最大.以产气量和TS去除率为指标,优选出最佳发酵条件是基质浓度6%,中温(35℃)发酵,以碳铵为添加剂.以此为条件,进行60d的续料发酵,结果为,TS去除率达68.64%,原料产气率299.9mL*gTS-1,容积产气率0.3224L*L-1d-1,CH4含量64%,符合沼气发酵供能的要求.     

熟制温度及切割方式对牛排食用品质的影响

为研究熟制温度以及切割方式对西餐红肉煎制牛排食用品质的影响,该文采集了12头中国西门塔尔公牛的背最长肌,研究了终点温度、切片厚度以及肌纤维走向对煎制牛排剪切力、质构剖面分析(texture profile analysis,TPA)以及感官品质的影响。结果显示:牛排的剪切力、蒸煮损失、硬度和咀嚼性随熟制温度的升高而增加(P0.05)。终点温度为72~100℃的牛排风味和总体可接受性得分显著高于45和60℃的牛肉(P0.05)。牛排剪切力随切片厚度增加而增加(P0.05);平行肌纤维切片的剪切力、硬度和咀嚼性显著低于垂直肌纤维切片(P0.05);切片厚度和肌纤维走向只对感官嫩度有显著影响(P0.05)。因此,煎制牛排的较佳熟制温度为80℃、切片厚度为10 mm和肌纤维走向为垂直肌纤维。研究结果为牛排生产企业、西餐厅以及宾馆饭店等生产、销售和加工牛排提供参考。     

Study on Influence of Fiber to Stability of Asphalt Concrete Pavement

The effect of fiber in asphalt mixtures has attracted general concern. For study of this problem, four kinds of fibers are chosen in this test. Asphalt and modified asphalt are adopted in asphalt mixtures AC-16I. The road performance influenced by additional fiber was analyzed impersonally,i, e. the stability of asphalt concrete under high temperature condition, anti-crack ability under low temperature condition, the water resistance and fatigue performance. It was shown through the research that the optimum asphalt content, air void rate, clearance rate of the mineral powder, saturation degree, and the flow value were increased and the density was decreased after adding the fiber. The road performance, such as the stability of asphalt concrete under high temperature condition, anti-crack ability under low temperature condition, water resistance and fatigue performance, was obviously improved,and the high temperature stability and fatigue performance improved most evidently. The fiber asphalt mixture performance reached and even exceeded the modified asphalt mixture performance. The modified asphalt performance after adding fiber would be improved more greatly.     

莴苣皮中膳食纤维提取工艺的研究

以新鲜莴苣皮为原料,采用化学方法制备水溶性膳食纤维（SDF）和水不溶性膳食纤维（IDF）。分析了莴苣皮中的常规营养成分,研究了浸提温度、浸提时间、pH值及浸提水量对SDF产率的影响。结果表明,莴苣皮中的蛋白质、脂肪含量较高。在温度100℃、pH值5.0、用水量25mL/g原料、浸提时间20min条件下,SDF产率高达6.96%;在料液比1∶17,碱液浓度0.50mol/L,温度65℃,浸提时间2.0h条件下,IDF产率高达47.62%。