The Impact of NaCl Substitution with KCl on Proteinase Activities Cell-Free Extract and Cell-Free Supernatant at Different pH Levels and Salt Concentrations: Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus

The effect of NaCl substitution with KCl at different pH levels (6.0, 5.5, and 5.0) and salt concentrations on proteinase activities of cell-free and supernatant of Lactobacillus delbrueckii ssp. bulgaricus 11824 (L. bulgaricus) and Streptococcus thermophilus MS (ST) was investigated. MRS broths were separately mixed with 4 salt treatments (NaCl only, 1NaCl:1KCl, 1NaCl:3KCl, and KCl only) at 2 different concentrations (5% and 10%) and incubated at 37 °C for 22 h. The cell pellets were used to prepare proteinase of cell-free extract and the cell-free supernatants were used as source of extracellular proteinases. The proteolytic activities and protein contents of both fractions were determined. The supernatants after incubation of both fractions with 3 milk caseins (α-, β-, κ-casein) were subjected to angiotensin-converting-enzyme inhibitory (ACE-inhibitory) activity and proteolytic activity by ortho-phthalaldehyde (OPA) method. Significant differences were observed in ACE-inhibitory activities and proteolytic (OPA) between salt treatments of cell-free extract and cell-free supernatant of L. bulgaricus and S. thermophilus at same salt concentration and same pH level. There was a significant effect of pH level and salt treatments interaction on ACE-inhibitory activity, OPA activity and azocasein activity. Practical Application: To reduce sodium concentration in cheese by substituting of NaCl with KCl, it was important to study the effect on starter culture proteinases which play a vital role in ripening and texture profile of cheese.     

盐对氨基改性SBA-15吸附Pb2+性能的影响研究

以三嵌段共聚物P123作为模板剂,正硅酸乙酯(TEOS)为硅源,3-氨丙基三乙氧基硅烷(APTES)为偶联剂,采用嫁接法制备氨基化SBA-15-KCl(n),并探究nHCl与nKCl的比对Pb2吸附效率的影响.采用X射线衍射(XRD)、透射电镜(TEM)、红外光谱(FT-IR)和N2吸附-脱附等手段对合成的样品进行表征,通过实验对改性后介孔材料的吸附性能和影响因素进行研究.结果表明:改性后材料对pb2吸附的最佳吸附时间为60 min,体系pH值为5,最佳吸附温度为40℃,当KC1的加入量达到0.0474 mol即nHCl∶nKCl =3∶7时,样品对Pb2+吸附率最佳可在95％左右.     

Kinetics studies during NaCl and KCl pork meat brining

We describe and quantify salt transfer processes during food processing using mathematical models. Our approach incorporates as novel elements: (i) a more rigorous determination of the salt diffusion kinetics by using the salt concentration of the liquid phase instead of the salt concentration of the overall samples, (ii) the use of novel, more accurate equilibrium conditions, (iii) the consideration of mass transfer coefficients in the boundary and (iv) the consideration of diffusion and salt transfer coefficients as functions of time. The methodology is used to determine the NaCl and KCl diffusion and transport coefficients during pork meat salting. Our results, combining experimental studies with a numerical study of a mathematical optimization problem point out the limitations of purely diffusive models and the need for more sophisticated models accounting for more physical and chemical processes taking place in meat during salting.     

Novel carboxymethyl derivatives of chitin and chitosan materials and their biomedical applications

Chitin and chitosan are natural biopolymers that are non-toxic, biodegradable and biocompatible. In the last decade, chitin and chitosan derivatives have garnered significant interest in the biomedical and biopharmaceutical research fields with applications as biomaterials for tissue engineering and wound healing and as excipients for drug delivery. Introducing small chemical groups to the chitin or chitosan structure, such as alkyl or carboxymethyl groups, can drastically increase the solubility of chitin and chitosan at neutral and alkaline pH values without affecting their characteristics; substitution with carboxyl groups can yield polymers with polyampholytic properties. Carboxymethyl derivatives of chitin and chitosan have shown promise for adsorbing metal ions, as drug delivery systems, in wound healing, as anti-microbial agents, in tissue engineering, as components in cosmetics and food and for anti-tumor activities. This review will focus on the preparative methods and applications of carboxymethyl and succinyl derivatives of chitin and chitosan with particular emphasis on their uses as materials for biomedical applications.     

用串联Al2O3/KCl柱分析1,3-丁二烯产品中痕量烃类杂质

为解决1,3-丁二烯中痕量烃类杂质丙炔等组分无法分离的问题,采用美国Agilent公司3种牌号大口径KCl型Al_2O_3柱,考察了1,3-丁二烯产品中痕量烃类杂质的分离情况,并建立了定量分析方法。结果表明:不同牌号Al_2O_3/KCl柱的分离效果差异较大,CP-Al_2O_3/KCl柱优于其他牌号;采用出峰顺序相同的2根Al_2O_3/KCl柱串联并优化色谱条件,能显著改善异戊烷、1,2-丁二烯、丙炔、正戊烷和1,3-丁二烯的分离,同时兼顾乙炔、丙二烯和异丁烷、正丁烷的良好分离,克服了Al_2O_3/KCl单柱无法满足关键组分基线分离的问题,同时满足痕量炔烃准确检测的需要。定量结果表明,各组分的检出限均低于2μg/g,相对标准偏差小于6.07%,加标回收率为84.5%～107.8%。     

Utilization of temporal dominance of sensations and time intensity methodology for development of low-sodium Mozzarella cheese using a mixture of salts

Evidence has linked excessive salt consumption to the development of chronic degenerative diseases. Therefore, special attention has been given to the consumption of healthier products with reduced sodium contents. This study aimed to develop a Mozzarella cheese with a reduced sodium content using a mixture of salts through acceptance testing and temporal sensory evaluation. The following 3 formulations of Mozzarella cheese were prepared: formulation A (control), which was produced only with NaCl (0% sodium reduction), formulation B (30% sodium reduction), and formulation C (54% sodium reduction). Every formulation was produced using a mixture of salts consisting of NaCl, KCl, and monosodium glutamate at different concentrations. The products underwent sensory acceptance tests, and the time intensity and temporal dominance of sensations were evaluated. The proportions of salts used did not cause strange or bad tastes but did result in lower intensities of saltiness. Mozzarella with low sodium content (B and C) had a sensory acceptance similar to that of traditional Mozzarella (A). Therefore, the use of a mixture of salts consisting of NaCl, KCl, and monosodium glutamate is a viable alternative for the production of Mozzarella, with up to a 54% reduction in the sodium content while still maintaining acceptable sensory quality.     

Selective Dissolution-Derived Nanoporous Design of Impurity-Free Bi2Te3 Alloys with High Thermoelectric Performance

Thermoelectric technology, which has been receiving attention as a sustainable energy source, has limited applications because of its relatively low conversion efficiency. To broaden their application scope, thermoelectric materials require a high dimensionless figure of merit (ZT). Porous structuring of a thermoelectric material is a promising approach to enhance ZT by reducing its thermal conductivity. However, nanopores do not form in thermoelectric materials in a straightforward manner; impurities are also likely to be present in thermoelectric materials. Here, a simple but effective way to synthesize impurity-free nanoporous Bi_0.4Sb_1.6Te₃ via the use of nanoporous raw powder, which is scalably formed by the selective dissolution of KCl after collision between Bi_0.4Sb_1.6Te₃ and KCl powders, is proposed. This approach creates abundant nanopores, which effectively scatter phonons, thereby reducing the lattice thermal conductivity by 33% from 0.55 to 0.37 W m⁻¹ K⁻¹. Benefitting from the optimized porous structure, porous Bi_0.4Sb_1.6Te₃ achieves a high ZT of 1.41 in the temperature range of 333–373 K, and an excellent average ZT of 1.34 over a wide temperature range of 298–473 K. This study provides a facile and scalable method for developing high thermoelectric performance Bi₂Te₃-based alloys that can be further applied to other thermoelectric materials.     

Na3AlF6-K3AlF6-AlF3熔体的电导率研究

通过连续改变电导池常数法(CVCC),用自制的电导率测试装置研究KCl溶液与熔融KCl的电导率。实验证明连续改变电导池常数法能满足于一般的科学实验要求,自制的电导率测试装置能满足常温实验和高温实验的电导率测试要求。通过此装置测定了钾冰晶石在(Na3AlF6+K3AlF6)熔体中的含量为40%,AlF3在(Na3AlF6+K3AlF6+AlF3)混合熔体中的含量分别为0、20%、24%和30%的电导率,实验还讨论了AlF3含量对电导率的影响。     

Effects of PVP and KCl concentrations on the synthesis of gold nanoparticles using a solution plasma processing

Application of plasma in an aqueous environment, so called Solution Plasma Processing (SPP) is a recent development. Solution plasma processing for the synthesis of gold nanoparticles by reducing HAuCl₄ in the presence of Polyvinylpyrrolidone (PVP) and potassium chloride (KCl) was investigated in this work. Effects of PVP and KCl concentrations on the size and the shape of the gold nanoparticles in SPP were studied using a UV-vis nir spectrophotometer, and high resolution transmission electron microscopy (HRTEM). The results showed that the shape and size of the nanoparticles were affected by various KCl and PVP concentrations. The average particle size of the gold nanoparticles synthesized by SPP decreased with an increase in PVP concentration and the particle shape became more spherical with the addition of KCl. The HRTEM results indicated that gold nanoparticles with a diameter less than 10 nm were single crystals, while particles with a diameter greater than 15 nm were polycrystalline.     

Preparation of hysteresis-free flexible perovskite solar cells via interfacial modification

In recent years, flexible perovskite solar cells have received extensive attention and rapid development due to their advantages of lightweight, portability, wearability and applications in near-space. However,due to the limitations of their preparation process and other factors, high-efficiency and large-area flexible perovskite solar cells still have a lot of room for development. In our work, a flexible perovskite solar cell(PEN/ITO/Sn O2/KCl/Cs0.05(MA0.17 FA0.83)0.95 Pb(I0.83 Br0.17)3/spiro/Au) was prepared using a low temperature(no higher than 100°C) solution process, and the device with the highest efficiency of 16.16%was obtained by adjusting the concentration of the KCl modified layer. Meanwhile, the efficiency of the large area(1 cm2) flexible solar cell was higher than 13%. At the same time, the passivation of the KCl interface modification layer inhibits the formation of the defect states, which reduced the surface recombination of the perovskite and improved the carrier transport performance, and the hysteresis effect of the device was also reduced accordingly.