响应面法优化异硫链霉菌LMZM利用玉米芯粉产木聚糖酶发酵培养基的研究

本研究采用响应面法对异硫链霉菌LMZM产木聚糖酶的发酵培养基进行优化。首先利用Plackett-Burman实验设计筛选出影响产酶的4个显著性因素:玉米芯粉、大豆粉、酵母粉和MgSO——4。在此基础上,研究不显著因素的最低添加量来降低生产成本,然后运用最陡爬坡法逼近最大响应值区域,最后利用中心复合设计确定显著性因素之间的交互作用及最佳组成。结果表明,玉米芯粉27.85 g/L、大豆粉16.25 g/L、酵母粉3.46 g/L、MgSO₄1.18 g/L、K₂HPO₄0.60 g/L、Na₂HPO₄0.40 g/L,木聚糖酶最大理论酶活可达117.80 U/m L,经3次平行实验验证,实际酶活平均值为116.63 U/m L与预测酶活相近,且比优化之前的酶活提高了1.28倍。      

Analysis of Serum Advanced Glycation Endproducts Reveals Methylglyoxal-Derived Advanced Glycation MG-H1 Free Adduct Is a Risk Marker in Non-Diabetic and Diabetic Chronic Kidney Disease

Accumulation of advanced glycation endproducts (AGEs) is linked to decline in renal function, particularly in patients with diabetes. Major forms of AGEs in serum are protein-bound AGEs and AGE free adducts. In this study, we assessed levels of AGEs in subjects with and without diabetes, with normal renal function and stages 2 to 4 chronic kidney disease (CKD), to identify which AGE has the greatest progressive change with decline in renal function and change in diabetes. We performed a cross-sectional study of patients with stages 2–4 CKD, with and without diabetes, and healthy controls (n = 135). Nine protein-bound and free adduct AGEs were quantified in serum. Most protein-bound AGEs increased moderately through stages 2–4 CKD whereas AGE free adducts increased markedly. Methylglyoxal-derived hydroimidazolone MG-H1 free adduct was the AGE most responsive to CKD status, increasing 8-fold and 30-fold in stage 4 CKD in patients without and with diabetes, respectively. MG-H1 Glomerular filtration flux was increased 5-fold in diabetes, likely reflecting increased methylglyoxal glycation status. We conclude that serum MG-H1 free adduct concentration was strongly related to stage of CKD and increased in diabetes status. Serum MG-H1 free adduct is a candidate AGE risk marker of non-diabetic and diabetic CKD.     

横观各向同性黏弹性沥青路面动力响应解析解

提出了移动荷载作用下各向异性层状地基上柔性路面结构动力响应分析的半解析解法。基于土-结构相互作用理论,建立了柔性路面-层状地基的动力耦合模型。对近场道路结构建立波数域有限元模型,基于精细积分及谱元法原理建立远场地基的谱元模型,利用子结构法来确定近-远场耦合界面处的边界条件,进而实现近场和远场结构的耦合,利用快速Fourier变换获得柔性路面在时空域的动力响应解答。该文方法既可以考虑道路结构的几何特性,也可以计入地基层状分布及各向异性特性的影响。近场有限域模型尺寸不会受到地基层数及层厚的影响,数值求解稳定。通过与解析解的对比,验证了提出方法的有效性与合理性。数值算例对比分析了道路-地基耦合模型与以往整体层状道路模型所得动力响应的差异,并讨论了道路结构层弹性模量的影响规律。

     

High-precision measurement of low reflectivity specular object based on phase measuring deflectometry

Phase measuring deflectometry (PMD) is a robust, noncoherent technique for the characterization of specular surface. For measuring high specular reflectivity surface, PMD can deliver micron radian range local gradient. However, when the measured surface has low specular reflectivity, the accuracy of the measured gradient is low since the captured fringe pattern shows low signal to noise ratio. The phase error characteristics in PMD system when testing low reflectivity surfaces are analyzed. The analysis illustrates that the random phase error increases rapidly while the nonlinear error drops slowly with the decreasing of the tested surface reflectivity. In order to attain high precision measurement of low reflectivity specular surface, a robust error reduction method based on wavelet de-noising is proposed to reduce the phase error. This error reduction method is compared with several other normally used methods in both simulation and experiment work. The method based on the wavelet de-noising shows better performance when measuring the low reflectivity specular surface.     

卷烟及烟草薄片原料、半成品、成品的成分对比研究

对比分析了卷烟、烟草薄片原料、半成品、成品中的还原糖、可溶性糖、淀粉和蛋白质等物质,寻找烟草薄片工艺改进方向。分别采用经典的DNS法对上述样品中的还原糖、可溶性糖、淀粉等成分进行定量分析,采用国家标准GB5009.5-2010对其中蛋白质进行定量分析。同一样品平行性较好,四种成分在卷烟、烟梗、烟末、木纤维、片基、未烤薄片、薄片中含量有明显差别。结果表明,水溶性成分在薄片加工过程中损失率加大。与卷烟相比,薄片原料及半成品、成品中的淀粉、蛋白质等不良组分含量较低。      

酒酒球菌在青梅汁中的生长及苹果酸乳酸发酵特性的研究

以青梅汁为原料,利用酒酒球菌的苹果酸-乳酸发酵（MLF）对青梅汁进行生物降酸的研究。结果表明:接种量为2.0×108CFU/mL,青梅汁的pH≥3.4时,MLF能正常进行,并使样品的酸度降低61.35%以上;接种量为2.6×107CFU/mL时,青梅汁的pH为3.6才能触发MLF,样品的酸度降低了77.60%;接种量为2.3×108CFU/mL,在pH3.6和4.0的青梅汁中,添加1.0g/100g的葡萄糖的样品,与不添加葡萄糖的样品相比,其酸度分别降低了27.04%和34.63%;在柠檬酸-柠檬酸钠缓冲体系中,酒酒球菌使体系酸度降低了26.40%,证实酒酒球菌可利用柠檬酸作为碳源,进行MLF。      

粘质沙雷氏菌的分离鉴定及产红色素培养基的优化

为确定KMR-3菌株的分类地位,对其进行了分类鉴定;为了提高其红色素产量,对发酵培养基进行了优化。以分离到的KMR-3菌株为供试材料,通过形态学、生理生化特征和16S rRNA基因序列分析对其进行了生物学分类鉴定。以LB液体培养基作为基础培养基,通过优化其不同组分（蛋白胨,酵母膏和NaCl）及含量以提高红色素产量。结果表明:KMR-3菌株归属为粘质沙雷氏菌,该菌株产红色素的最佳培养基为5g/L胰蛋白胨和1%甘油,pH5.0,温度28℃;该条件下,色素产量是基础培养基的13.4倍。该培养基蛋白用量少,促进粘质沙雷氏菌产生大量红色素,为其大规模生产提供依据。      

3种保鲜方式对大平顶枣保鲜效果的影响

以朝阳大平顶枣为原料,研究其在(4±0.3)℃低温条件下,利用氯化钙、迷迭香提取物、热水处理3种常用保鲜方法对大平顶枣采后贮藏特性的影响。通过对大平顶枣的腐烂率、维生素C含量、可滴定酸含量、质构特性的变化以及风味物质检测,比较了不同处理方式对大平顶枣的贮藏保鲜效果。实验结果表明,2.0%氯化钙溶液浸渍、0.2%迷迭香提取物溶液浸渍、45℃热水浸泡均具有很好的保鲜效果。钙盐处理能有效抑制大枣的果皮硬度下降,保持枣果中VC和可滴定酸含量;迷迭香提取物显著(p<0.05)降低了大枣腐烂率,保持枣果VC含量;热水浸泡处理可显著地(p<0.05)提高好果率,延缓鲜果衰老。电子鼻检测的结果表明不同保鲜处理方式下,大枣中的芳香成分的变化速率和规律并不相同,采用线性判别分析(LDA)方法能很好地区分不同新鲜度的大平顶枣。      

葡萄梗(茎)中的生物活性物质研究现状

葡萄梗(茎)是葡萄加工业副产物之一,富含高附加值的生物活性成分,可用于食品、医药和化妆品等工业领域,但较少被人们关注和开发。本文介绍了葡萄梗(茎)中生物活性物质的分布和分离纯化的研究现状,旨在为葡萄生产废弃物葡萄梗(茎)的综合利用提供一定的参考和借鉴。      

巴美肉羊肌纤维特性与糖酵解潜力相关性的研究

以巴美肉羊为实验材料,测定了不同部位肌肉(背最长肌、股二头肌和冈上肌)肌纤维组织学特性和糖酵解潜力,研究了不同部位肌肉肌纤维组织学特性的差异,分析了肌纤维特性和糖酵解潜力之间的相关关系。结果表明,三个部位肌肉的肌纤维中以ⅡB型肌纤维为主。Ⅰ型、ⅡA型肌纤维在背最长肌中含量最少,股二头肌中次之,冈上肌中最多。ⅡB型肌纤维与之相反。Ⅰ型肌纤维直径和横截面积在三块肌肉间存在显著差异(p<0.05)。冈上肌中的ⅡA型肌纤维的直径和横截面积显著大于其他两个部位(p<0.05),背最长肌中的ⅡB型肌纤维的直径和横截面积小于其他两个部位(p<0.05)。背最长肌的糖酵解潜力值显著高于股二头肌和冈上肌的(p<0.05)。糖酵解潜力与Ⅰ型、ⅡA型肌纤维个数比例和面积比例成显著的负相关(p<0.05),与ⅡB型肌纤维数量比和面积比成显著的正相关(p<0.05)。