顶空气相色谱-质谱法测定橡胶防老剂4020中的甲基异丁基酮和苯胺

通过优化不同的平衡条件,建立了顶空气相色谱-质谱法测定防老剂4020中甲基异丁基酮和苯胺的方法。结果表明:在称样量为0. 5 g、顶空自动进样器的平衡温度为160℃、平衡时间为90 min的条件下,甲基异丁基酮和苯胺质量浓度线性关系良好,相关因数分别为0. 995和0. 989;方法检出限均为1 mg·kg~(-1);回收率为90%～110%,相对标准偏差为4. 4%～8. 0%。     

Comparative evaluation of conventional and advanced frying methods on hydroxymethylfurfural and acrylamide formation in French fries

In this study, deep fat frying, microwave frying, air frying, and vacuum frying processes were used to mitigate acrylamide (AA) and hydroxymethylfurfural (HMF) formation during the frying of French fries. The highest reduction of AA and HMF range was found in vacuum frying (61.42–81.14%), followed by air frying (59.2–78.7%), as compared to deep fat frying and microwave frying. Both these method samples also showed significantly (p < 0.05) lower browning index (BI) and CIE a* values. Principal component analysis (PCA) was used to visualize the effects of the different frying methods on AA and HMF content. Vacuum frying and air frying were found to be alternative frying technologies to minimize AA and HMF content in French fries.     

Changes in the physicochemical,structural and emulsifying properties of chicken myofibrillar protein via microfluidization

Microfluidization is a novel and effective technology to improve the properties of myofibrillar protein. The effects of microfluidization with varying pressures (0–120 MPa) on the physicochemical, structural and emulsifying properties of chicken myofibrillar protein (CMP) were studied. Microfluidization treatment remarkably increased the absolute ζ-potential, contact angle, solubility, emulsifying ability and emulsifying stability of CMP. Simultaneously, the turbidity of CMP decreased. After microfluidization treatment, more α-helix structures were transformed into disordered structures, more hydrophobic and negatively charged groups were exposed, leading to improvements in CMP properties. After 90 MPa treatment, the absolute ζ-potential, storage modulus, loss modulus and dynamic apparent viscosity of CMP-camellia oil emulsion reached the maximum values. The hydrophobic interaction between CMP and camellia oil induced CMP to expose more hydrophobic and negatively charged groups, leading to the improved emulsifying properties of CMP. Our results demonstrate that microfluidization treatment has great potential to improve the product qualities of emulsion-type meat products.     

The effect of operational parameters on diamond tools of frame sawing system: Wear characteristics and optimization in stone processing

A series of sawing experiments was carried out to investigate the effect of operational parameters on the wear characteristics of diamond segment. And the wear mechanism of diamond segment was studied through micro-morphology. The analysis presented that the wear mechanisms of segment metal matrix are mainly attributed to abrasive wear and erosion wear, the wear mechanism of diamond particles mainly includes cleavage fracture caused by the impact load and abrasion caused by scratching. The effect of sawing parameters on the wear rate of segment matrix is consistent with that of diamond particles. The wear resistance of segment matrix increases with the increase of the proportion of diamond particles with micro-fractured and complete crystalline shape, and decreases with the increase of the proportion of diamond particles with macro-fractured and pulled-out. Furthermore, the predicted model was established to evaluate the segment wear per unit by using Design Expert software, and the optimum sawing parameters obtained as a result of the optimization was investigated to provide some guidance for the processing of the enterprise.     

Performance assessment of food safety management systems in animal-based food companies in view of their context characteristics: A European study

Recurrently the question arises if efforts in food safety management system (FSMS) have resulted in effective systems in animal-based food production systems. The aim of this study was to gain an insight in the performance of FSMS in European animal-based food production companies in view of their typical context characteristics. Hundred European companies (from Belgium, Spain, The Netherlands, Greece, Italy, and Hungary) varying in company size, and producing different types of fresh and processed animal-derived products (dairy, beef/lamb, poultry, and pork) were assed using a diagnostic instrument. Results indicated that most participating companies adapted adequately their food safety management systems to the riskiness of their context characteristics resulting in rather good safety output scores. Only a small group have overall basic systems and operate in a moderate or moderate-high risk context, which was reflected in lower safety output scores. Companies tend to invest first in the control strategies whereas assurance activities such as verification and validation seem to require more time and effort to achieve advanced levels. Our study demonstrated that also small and medium enterprises managed to have advanced systems, and achieve a good safety output. However, their typical organisational characteristics such as less resources (educated staff, laboratory facilities, time), more restricted formalisation (restricted use of procedures and formal meetings), limited information systems, but more stable workforce, might require more tailored support from government and/or branch organisations to develop towards advanced systems in the case of high-risk products and processes. More in-depth studies to successful SMEs could give insight in best practices to improve FSMS performance.     

Advanced Composite Solid Electrolytes for Lithium Batteries: Filler Dimensional Design and Ion Path Optimization

Composite solid electrolytes are considered to be the crucial components of all-solid-state lithium batteries, which are viewed as the next-generation energy storage devices for high energy density and long working life. Numerous studies have shown that fillers in composite solid electrolytes can effectively improve the ion-transport behavior, the essence of which lies in the optimization of the ion-transport path in the electrolyte. The performance is closely related to the structure of the fillers and the interaction between fillers and other electrolyte components including polymer matrices and lithium salts. In this review, the dimensional design of fillers in advanced composite solid electrolytes involving 0D–2D nanofillers, and 3D continuous frameworks are focused on. The ion-transport mechanism and the interaction between fillers and other electrolyte components are highlighted. In addition, sandwich-structured composite solid electrolytes with fillers are also discussed. Strategies for the design of composite solid electrolytes with high room temperature ionic conductivity are summarized, aiming to assist target-oriented research for high-performance composite solid electrolytes.     

Cyanobacterial blooms in the central basin of Lake Erie: Potentials for cyanotoxins and environmental drivers

Lake Erie western basin (WB) cyanobacterial blooms are a yearly summer occurrence; however, blooms have also been reported in the offshore waters of the central basin (CB), and very little is known about what drives these blooms or their potential for cyanobacterial toxins. Cyanobacteria Index was quantified using MODIS and MERIS data for the CB between 2003 and 2017, and water samples were collected between 2013 and 2017. The goals were to 1) quantify cyanobacteria, 2) determine environmental drivers of CB blooms, and 3) determine the potential for cyanobacterial toxins in the CB. Dolichospermum (Anabaena) occurred in the CB during July before the onset of the WB bloom, and then in August and September, the cyanobacteria community shifted towards Microcystis. The largest Dolichospermum blooms (2003, 2012, 2013, and 2015) were associated with reduced water clarity (Secchi disk depth?<?4?m), whereas large CB Microcystis blooms (2011 and 2015) were associated with large WB blooms. Dolichospermum blooms occurred in high nitrate concentrations (>20?μmol/L) and high nitrogen-to?phosphorus ratios (>100), which indicate nutrient concentrations or ratios did not select for Dolichospermum. Additionally, the sxtA gene, but not mcyE or microcystins, were detected in the CB during July 2016 and 2017. The mcyE gene and microcystins were detected in the CB during August 2016 and 2017. The results indicate the CB's potential for cyanotoxins shifts from saxitoxins to microcystins throughout the summer. Continued monitoring of cyanobacteria and multiple cyanobacterial toxins is recommended to ensure safe drinking water for CB coastal communities.     

TGA-FTIR与Py-GC/MS分析医用硅橡胶

用热重分析(TGA)-傅里叶变换红外光谱(FTIR)联用和裂解(Py)-气相色谱(GC)/质谱(MS)联用对两个医用硅橡胶试样的热分解过程进行分析。研究表明:通过FTIR分析,推断两个医用硅橡胶试样的主要成分为甲基取代硅氧烷,其中一个试样的填料可能为硫酸钡和白炭黑,而另一个试样的填料可能仅为白炭黑;两个医用硅橡胶试样的裂解产物均为环状二甲基硅氧烷,主要成分为六甲基环三硅氧烷和八甲基环四硅氧烷;裂解温度越高,越易出现相对分子质量较大的环状二甲基硅氧烷。TGA-FTIR和Py-GC/MS分析可以为医用硅橡胶的鉴定和裂解回收提供依据。     

Ternary nucleation: kinetics and application to water–ammonia–hydrochloric acid system

The ternary nucleation of an ideal mixture of three alcohols and a non-ideal mixture of water, ammonia and hydrochloric acid, which is relevant in atmosphere, have been investigated theoretically. In the ideal mixture of three alcohols, the nucleation rates obtained using simplified kinetic approach are compared with the nucleation rates given by a detailed kinetic model. The simplified model is seen to underestimate nucleation rates by 2–3 orders of magnitude. This is mainly due to the crude estimate for the Zeldovich factor in the simplified model. We have proposed a modification to the simplified model. The improved model gives order-of-magnitude estimates for the nucleation rates. The ternary nucleation of water–ammonia–hydrochloric acid is studied with the improved model. The results have been compared with binary nucleation of water and ammonium chloride. The results show that water–ammonia–hydrochloric acid mixture is effectively a two-component system.     

Biotransformation rates of chloroform under anaerobic conditions—I. Methanogenesis

Biotransformation of chloroform (CF) was studied in a methanogenic environment utilizing acetic acid as the primary substrate. CF removal efficiency of more than 99% was achieved in a chemostat, fed constant acetic acid concentration (2510 mg/l) and different CF concentrations, up to 16.74 μM. Biological methane potential tests were conducted in serum bottles using the culture from the chemostat with an average biomass concentration of 53 mg/l. The culture exhibited a maximum rate of CF transformation of 0.26 μM/h corresponding to an initial CF concentration of 1.25 μM. At initial CF concentrations higher than 2.76 μM, the rate of CF transformation became constant at 0.06 μM/h. CF present at any concentration inhibited the utilization of acetic acid, and at CF concentrations equal to or exceeding 2.7 μM, the culture was completely inhibited and no acetic acid was utilized by the culture even after the CF was completely degraded. The culture transformed CF without the addition of acetic acid, but the addition of acetic acid considerably increased the rate of biotransformation. However, increase in acetic acid concentration beyond 50 mg/l did not increase the rate. The culture exhibited higher rates of CF biotransformation when it was acclimated with higher influent concentration of CF in a chemostat. Reductive dehalogenation was one of the pathways for the transformation of CF leading to the formation of dichloromethane which was also transformed by the culture.