Integration of high and low field 1H NMR to analyse the effects of bovine dietary regime on milk metabolomics and protein-bound moisture characterisation of the resulting mozzarella cheeses during ripening

The influence of dairy cow feeding regime was investigated using ¹H nuclear magnetic resonance (NMR). Two different NMR analytical systems were deployed: high field ¹H NMR to investigate the influence on milk metabolomics and low field NMR to characterise proton relaxation linked to changes in the state of mozzarella cheese moisture during ripening. The metabolomics results showed that grass-based feeding increased the concentration of a biological marker that signifies near-organic milk production conditions. On the other hand, the investigation of cheese moisture distribution showed that grass-based diets reached final moisture partitioning in a shorter time, which implied the formation of a more compact protein structure in the cheese matrix. These results indicate that pasture-based dairying may be differentiated in terms of the provenance of milk produced along with the accrual of additional benefits during ripening of the resulting mozzarella cheeses.     

细菌纤维素/碳纳米管/MnO2复合超级电容器电极

基于细菌纤维素(BC)的三维多孔及柔性支架结构和碳纳米管(MWCNT)的优良导电性,构筑起BC/MWCNT自支撑导电基底。其中,二者通过氢键紧密结合,协同赋予复合基底优良的电导率和机械性能。然后将二氧化锰(MnO₂)电沉积在该基底上,构建了一种新型的BC/MWCNT/MnO₂薄膜电极。BC/MWCNT复合膜的多孔结构、电解质吸收特性及蜂窝状活性MnO₂纳米片的桥连结构,赋予其出色的电化学性能(在1 mA cm_-2^{的电流密度下},其面积比电容和质量比电容分别达到1.17 F cm_-2^和200 F g_-1⁾和显著的循环稳定性(在20 mA cm_-2^{的电流密度下进行}10000次循环后,其比电容保留率稳定在96%)。这种无粘合剂的薄膜电极制备简便且成本低廉,在开发柔性储能器件方面具有巨大潜力。关键词：细菌纤维素(BC)；碳纳米管(MWCNT)；二氧化锰(MnO₂)；膜电极；电化学性能中图分类号：TQ630 文献标识码： A 文章编号：1003-5214 (2020) 01-0000-00     

封闭型无溶剂聚氨酯超细纤维合成革基布的制备及性能

将聚酰胺6-碱溶性聚酯(PA6-COPET)海岛纤维非织造布与封闭型无溶剂聚氨酯(BSFPU)通过浸渍、碱减量和后整理等工艺制备了BSFPU超细纤维合成革基布。分析和探讨了BSFPU浸渍量对超细纤维合成革基布力学性能和卫生性能的影响,采用电子扫描显微镜对其微观结构进行表征。结果表明:海岛纤维经过减量后形成具有37根纤维且单纤直径约为3 μm的束状超细纤维,BSFPU超细纤维合成革基布形成了近似天然皮革的微观结构。随着BSFPU浸渍量的提高,碱减量过程减量率从31.59wt%降低至28.22wt%;BSFPU超细纤维合成革基布的断裂伸长率和撕裂强度下降;拉伸强度保持不变直到浸渍量大于100wt%时开始下降;透气量从50 086 mL/(m2·s)降低至24 757 mL/(m2·s),透水汽量从790.47 mg/(10 cm2·24 h)下降至488.70 mg/(10 cm2·24 h)。经过测试,BSFPU超细纤维合成革基布能够满足行业检测标准,并且其卫生性能明显优于市售溶剂型聚氨酯超细纤维合成革基布。      

空心柱状CuS的制备及其降解染料性能

以硝酸铜、硫代硫酸钠为原料,采用沉淀法制备空心柱状CuS。通过扫描电子显微镜(SEM)、透射电镜(TEM)、X射线衍射仪(XRD)和傅里叶红外光谱测定仪(FT-IR)对所制备的空心柱状CuS的形貌及物相进行表征。同时,以甲基橙染料(MO)为目标污染物,研究空心柱状CuS的降解性能。结果表明:所制备的空心柱状CuS由CuS纳米片组装而成,其直径在400nm,长度为2.0μm左右。空心柱状CuS与H_2O_2组成的类芬顿体系对染料具有优异的降解能力,110min后甲基橙的降解率可高达86.6%,远优于实心结构CuS对染料的降解能力。     

Segregated highly conductive linear low-density polyethylene/graphene nanoplatelet composite through aqueous dispersing and self-leveling method

Construction of segregated structure is an effective way of preparing highly conductive composite. Here, we report an environmentally friendly method to prepare highly conductive linear low-density polyethylene/graphene nanoplatelets composite with segregated structure (s-LLDPE/GN) and low GN content. Firstly, GN coated LLDPE granules are prepared through aqueous dispersing and gradually drying. Then, the s-LLDPE/GN composites are obtained by melting and self-leveling without extra pressure. This method not only favors the forming of GN segregated network, but also allows certain fusing of the polymer at the interfaces that contribute to good mechanical strength of the composite. The electrical conductivity of the composite increases to 4.5 S/m when the GN content is 1.0 wt%. The composite with 0.5 wt% GN shows 10⁻¹ S/m electrical conductivity, and retains 82% of the tensile strength of pure LLDPE. The facile and green process in this method can be applied in many other polymer composites and show high potential for industrial application.     

Synthesis and nonlinear optical properties of novel T-type polyurethanes with high thermal stability of second harmonic generation

Methyl 2,5-di-(2′-hydroxyethoxy)benzylidenecyanoacetate (3) was prepared by hydrolysis of methyl 2,5-di-(2′-vinyloxyethoxy)benzylidenecyanoacetate (2). Diol 3 was condensed with 2,4-toluenediisocyanate (TDI) and 3,3′-dimethoxy-4,4′-biphenylenediisocyanate (DMBPI) to yield novel T-type polyurethanes (4–5) with 2,5-dioxybenzylidenecyanoacetate group as a nonlinear optical (NLO) chromophore, which constitutes a part of the polymer backbone. The resulting polyurethanes 4–5 were soluble in common organic solvents such as acetone and dimethylsulfoxide (DMSO). Polymers 4–5 showed a thermal stability up to 250 °C in thermogravimetric analysis (TGA) thermograms with glass transition temperature (T_g) values from differential scanning calorimetry (DSC) thermograms near 145 °C. The second harmonic generation (SHG) coefficients (d₃₃) of poled polymer films were around 2.36 × 10⁻⁹ esu. These poled polymers exhibited a thermal stability of dipole alignment up to T_g, and no SHG decay was observed below 150 °C due to the partial main chain character of the polymer structure, which is acceptable for NLO device applications.     

构型对正多边形蜂窝异面缓冲性能的影响

目的 利用有限元法研究应变率不敏感的双线性各向同性应变硬化正多边形（等边三角形、正方形、正六边形和正八边形）蜂窝的异面缓冲性能。方法 建立基于正多边形蜂窝特征单元的异面冲击分析有限元模型，提出最佳应变这一缓冲性能评价新指标，基于此重新定义各能量吸收评价指标，形成新缓冲性能评价方法。结果 以此获取不同相对密度的各正多边形蜂窝在不同冲击速度下的变形模式和应力-应变曲线，以及平均平台应力、比能量吸收和冲击力效率等评价指标值，并进行了分析。结论 给定相对密度下，正八边形蜂窝具有最大的异面平均平台应力；正多边形蜂窝的比能量吸收与冲击速度成二次关系；定密度的正六和八边形蜂窝的冲击力效率优于等边三角形和正方形蜂窝。     

基于半色调实地的纽介堡方程修正方法

目的从网点墨量与实地墨量不同的角度出发,构建基于半色调实地三刺激值的纽介堡方程修正模型,从而提高纽介堡方程的计算精度。方法以符合G7认证的印刷标准文件为研究对象,从网点墨量与实地墨量不同的角度出发,通过求解半色调实地三刺激值,构建基于半色调实地三刺激值的纽介堡方程修正模型,利用色差法对该修正模型进行精度验证。结果验证结果表明,修正模型色差精度最大可以提高2.2 NBS,平均色差精度可以提高1.0 NBS。结论基于半色调实地三刺激值的纽介堡方程修正模型能够有效提高方程精度,研究结果对于印刷分色具有重要意义。     

阳离子无氟丙烯酸酯防水剂的制备及应用

以甲基丙烯酸十八烷基酯（ SMA）、甲基丙烯酰胺（ MAA）、丙烯酸羟乙酯（ HEA）和甲基丙烯酰氧乙基三甲基氯化铵（ DMC）为单体，十六烷基三甲基溴化铵（ CTAB）和聚氧乙烯醚（ AEO-20）为复合乳化剂，偶氮二异丁脒盐酸盐（ AIBA）为引发剂，采用细乳液聚合法制备无氟阳离子丙烯酸酯防水剂。分析了聚合物温度、乳化剂用量和交联剂用量（ HEA）对乳胶性能的影响。结果显示：乳化剂为 7%，HEA为 2%，反应温度为 80 ℃，反应时间为 5h，合成的乳胶性能最佳。当防水剂用量为 100 g/L时，整理后的棉织物显示了较强的疏水性能，其接触角达到 139°。经过 25次洗涤后，棉纤维仍然具有较高的接触角，说明具有优良的耐洗性能。     

Tailoring the structure of layered double oxide for enhancing adsorption of anionic chemicals on collagen fibers in chrome-free leather processing

Clean Technologies and Environmental Policy - Post-tanning process is crucial to improve the physical properties of leather in leather manufacture. However, enormous amounts of organic wastewater...