液相色谱法在枸杞甜菜碱含量测定中的应用

枸杞作为药食两用植物,具有益精明目、养肝补肾等功效。甜菜碱是一种季铵型水溶性生物碱,是枸杞中的主要活性成分,具有良好的医用及药用价值,如促进脂肪代谢、调节渗透压、抗应激等功效,目前已作为一类新型饲料添加剂工厂化生产,被广泛用于动物养殖业中。甜菜碱检测方法主要有比色法、酸碱滴定法、凯氏定氮法、薄层色谱法等。其中,液相色谱法因其高效、准确的特点,在甜菜碱的分析测试中得到了广泛的应用。根据甜菜碱的化学结构特点,主要采用氨基柱、亲水性色谱柱、离子交换色谱柱,并结合二极管阵列检测器、蒸发光散射检测器、质谱检测器等进行检测。本文综述了液相色谱法在枸杞中甜菜碱含量测定中的研究进展,为更好地开发枸杞中甜菜碱的应用价值提供理论基础。     

甘氨酸甜菜碱及复合纤维素酶对酱油发酵的影响

将甘氨酸甜菜碱作为渗透压保护剂,于酱醪上罐时(0d)或酱醪发酵30d后添加到高盐稀态酱油发酵的酱醪中,同时添加外源复合纤维素酶,观察其对酱醪发酵的影响。结果表明：在酱醪上罐时(0d)或酱醪发酵30d后同时添加不同质量分数的甘氨酸甜菜碱(0.20%、0.30%)及质量分数0.15%的复合纤维素酶(105EGu/100g酱醪),均能有效提高发酵酱油中蛋白质转化率,达2.26%～7.92%。添加甘氨酸甜菜碱能显著改善高盐稀态发酵酱油头油品质,平均缩短发酵时间15d左右;另外,在酱醪发酵30d后再添加甘氨酸甜菜碱和外源复合纤维素酶其效果更佳,同0d时添加相比,蛋白质转化率平均提高了3.17%。     

Molecular-Crowding Effect Mimicking Cold-Resistant Plants to Stabilize the Zinc Anode with Wider Service Temperature Range

Growth of dendrites, the low plating/stripping efficiency of Zn anodes, and the high freezing point of aqueous electrolytes hinder the practical application of aqueous Zn-ion batteries. Here, a zwitterionic osmolyte-based molecular crowding electrolyte is presented, by adding betaine (Bet, a by-product from beet plant) to the aqueous electrolyte, to solve the abovementioned problems. Substantive verification tests, density functional theory calculations, and ab initio molecular dynamics simulations consistently reveal that side reactions and growth of Zn dendrites are restrained because Bet can break Zn²⁺ solvation and regulate oriented 2D Zn²⁺ deposition. The Bet/ZnSO₄ electrolyte enables superior reversibility in a Zn–Cu half-cell to achieve a high Coulombic efficiency >99.9% for 900 cycles (≈1800 h), and dendrite-free Zn plating/stripping in Zn–Zn cells for 4235 h at 0.5 mA cm⁻² and 0.5 mAh cm⁻². Furthermore, a high concentration of Bet lowers the freezing point of the electrolyte to −92 °C via the molecular-crowding effect, which ensures the stable operation of the aqueous batteries at −30 °C. This innovative concept of such a molecular crowding electrolyte will inject new vitality into the development of multifunctional aqueous electrolytes.     

中低温清洁压裂液BVES-80的性能评价

开发了一种新型甜菜碱表面活性剂压裂液BVES-80。该压裂液优化配方为2.5% 甜菜碱表面活性剂DBA2-12+4.0% KCl+0.5%水杨酸钠+1.0%异丙醇+自来水。对BVES-80 压裂液性能的评价结果表明,NaCl、CaCl₂、MgCl₂加量为3%时,压裂液的黏度分别为337、370、394 mPa·s,耐盐性较好。压裂液静置7 d后的黏度为321 mPa·s,变化较小,稳定性较好。在170 s^-1下连续剪切1 h后的黏度分别大于50（60℃）和30（80℃）mPa·s,在中低温下的耐温抗剪切能力良好。在30℃、0.01~10 Hz条件下,压裂液储能模量G′始终大于耗能模量G″,且G′大于10 Pa,G″大于0.3 Pa,黏弹性较好。60℃下,陶粒在BVES-80清洁压裂液中的沉降速度为0.14 mm/s,远小于0.5%胍胶压裂液的值（1.50 mm/s）,携砂性能较好。在30℃下与煤油混合可在12 h内彻底破胶,破胶液黏度小于5 mPa·s,残渣含量23.46~54.37 mg/L,破胶液表面张力26.3~27.5 mN/m,破胶液与煤油的界面张力0.55~0.62 mN/m。该体系在80℃下的滤失系数为4.75×10-4 m/min^0.5,对岩心的渗透率伤害率仅为7.4%,适合不超过80℃的中低温低渗地层的储层改造。     

耐温抗盐甜菜碱表面活性剂的表征及性能研究

本文合成了一种耐温抗盐表面活性剂,通过红外光谱、拉曼光谱以及元素分析考察了该表面活性剂的结构,并研究了其表界面活性和乳化性能。研究结果表明：所合成产物与目标产物———羟磺基甜菜碱一致;羟磺基甜菜碱溶液具有较低的表面张力,临界胶束浓度为8.099×10^-5 mol/L;在0.5～3.0 g/L浓度范围内,羟磺基甜菜碱溶液与原油间的界面张力（稳定值）均能够达到超低,且在30℃～80℃较宽的温度范围内均能达到超低界面张力;此外羟磺基甜菜碱还具有一定的乳化能力。羟磺基甜菜碱作为一种具有良好应用前景的表面活性剂,有望应用于国内外高温高盐油藏。     

Fractionation of baker's yeast vinasse via ultrafiltration: assessment of feasibility

The potential of vinasse, gained from baker′s yeast production for the recovery of valuable molecules (invertase, food grade proteins and betaine), has been assessed. Particularly natural betaine, a trimethyl derivative of glycine, attracts more and more attention in human and animal nutrition. In this work, a straightforward membrane-based process for the recovery of natural betaine and a very promising betaine-rich protein fraction from fermentation broth of baker′s yeast was developed. The difficult separation of external invertase from yeast cells was observed in this work. Anyway, a residual invertase activity was found in vinasse, but it could not be efficiently purified to generate an industrial-strength product. The presented process can be easily implemented in a conventional baker's yeast production plant by integrating an ultrafiltration station and an adsorption system. Based on our calculations, a potential recovery up to 1486 t year⁻¹ of betaine-rich proteins (5 € kg⁻¹) and 593 t year⁻¹ Betafin^® similar natural betaine (6–7 € kg⁻¹) may be achieved.     

Zwitterionic Osmolyte‐Based Hydrogels with Antifreezing Property,High Conductivity,and Stable Flexibility at Subzero Temperature

Conductive hydrogels have emerged as fascinating materials applied in flexible electronics because of their integrated conductivity and mechanical flexibility. However, the large amounts of water in conductive hydrogels inevitably freeze at subzero temperature, causing a reduction of their ionic transport ability and elasticity. Herein, the bioinspired antifreezing agents—zwitterionic osmolytes (e.g., betaine, proline) are first proposed to prevent ammonium chloride‐containing Ca‐alginate/polyacrylamide hydrogels from freezing. With a facile one‐pot solvent displacement method, the zwitterionic osmolytes can displace the water molecules inside the hydrogels. Due to the excellent freeze tolerance of zwitterionic osmolytes, the resulting zwitterionic osmolyte‐based hydrogels exhibit outstanding ionic conductivity (up to ≈2.7 S m^?1) at ?40 °C, which exceeds the conductivities of most reported conductive hydrogels. Meanwhile, they present stable mechanical flexibility over a wide temperature range (?40 to 25 °C). More importantly, two types of the resulting hydrogel‐based flexible electronics, including a capacitive sensor and a resistive sensor, can maintain their response function at ?40 °C. This work offers a new solution to fabricate conductive hydrogels with antifreezing ability, which can broaden the working temperature range of flexible electronics.     

Unperturbed dimensions of a zwitterionic polymethacrylate

Values of intrinsic viscosity [ζ] measured in 2,2,2-trifluoroethanol (TFE) and in 1·0M aq. NaCl solution mean square radii of gyration s²_z and weight-average molecular masses M _w measured in TFE at 298 K for 12 well fractionated poly[N-(3-sulphopropyl)-N-methacrylooxyethyl-N,N-dimethylammonium betaine] (PSPE) samples have been used to derive the unperturbed dimensions (<r²₀/M)^1/2 via different extrapolation procedures. Cloud point curves for PSPE fractions in 0-05M aq. NaCl yielded an upper critical solution temperature (0) of 308 K, which was confirmed turbidimetrically, visco-metrically, and by light scattering, thus enabling the unperturbed dimensions to be determined directly. The mean value of (r²₀/M)^1/2 by all procedures was 0-052nm g-1/2 mol1/2 which, in conjunction with the corresponding quantity calculated on the basis of free rotation, affords a value of 2-83 for the steric factor α. From values of [ζ] in 2·0M aq. NaCl solution over the interval 283–343 K, the value of dlnr²_o/dT was derived as ?8·5 × 10^?4 deg^?1. The values of the long range interaction parameter β and the interaction parameter χ confirm that TFE is a thermodynamically better solvent than l·0M aq. NaCl solution for PSPE.     

Evaluation of the irritant capacity of decyl polyglucoside

Synopsis
The irritant capacity of several anionic, amphoteric and non-ionic surfactants has been studied by non-invasive techniques, specifically by evaporimetry, laser Doppler flowmetry and one-dimensional cutaneous ecography. Some of the surfactants most frequently used in shampoos and shower/foam gels were selected for testing. A series of aqueous solutions containing 5% of the active material in these products was patched onto normal skin; controls for comparison were set up with water and with sodium lauryl sulphate (SLS), a recognized irritant standard substance.
It was deduced from the results obtained that, of the surfactants tested, the one showing the lowest irritant capacity is decyl polyglucoside, followed in increasing order of irritant capacity, by cocoamidopropyl betaine, magnesium laurylether sulphate and sodium laurylether sulphate.
Résumé
La capacitée irritante des beaucoups des tensioactives anioniques, anfoteric et no-ioniques on étéétudiées avec métodes no invasives, particulierment avec évaporimetrie, laser DOPPLER et écografie cutanée unidimensionel. On á selectionné pour son texture quelques tensioactives utilisée plus frequement en shampooing et gel de bains ou douche.
On á formulé une series des solutions ocuoses en contenent un 5% des matieres actives quón á emplâtre en peaux normaux, on áétablie des contrôles des comparations avec de l'eau et sodium lauryl sulphate (SLH) une substancie de reconnue irritabilitée.
Des resultats obtenue on á deduit que tous les tensioactives quón á textés, celui qui á montré le meneur capacité irritant il fut decyl polyglucoside, suivi en ordre montante de capacité irritant por cocamidopropyl betaine, magnesium laureth sulphate et sodium laureth sulphate.