Synthesis of a Novel Chitosan/Basil Oil Blend and Development of Novel Low Density Poly Ethylene/Chitosan/Basil Oil Active Packaging Films Following a Melt-Extrusion Process for Enhancing Chicken Breast Fillets Shelf-Life

An innovative process for the adsorption of the hydrophobic Basil-Oil (BO) into the hydrophilic food byproduct chitosan (CS) and the development of an advanced low-density polyethylene/chitosan/basil-oil (LDPE/CS_BO) active packaging film was investigated in this work. The idea of this study was the use of the BO as both a bioactive agent and a compatibilizer. The CS was modified to a CS_BO hydrophobic blend via a green evaporation/adsorption process. This blend was incorporated directly in the LDPE to produce films with advanced properties. All the obtained composite films exhibited improved packaging properties. The film with 10% CS_BO content exhibited the best packaging properties, i.e., 33.0% higher tensile stress, 31.0% higher water barrier, 54.3% higher oxygen barrier, and 12.3% higher antioxidant activity values compared to the corresponding values of the LDPE films. The lipid oxidation values of chicken breast fillets which were packaged under vacuum using this film were measured after seven and after fourteen days of storage. These values were found to be lower by around 41% and 45%, respectively, compared with the corresponding lipid oxidation values of pure LDPE film.     

低频标准真空涨落的测量

采用自平衡零拍方案, 对低频段的标准量子真空涨落进行了测量. 实验确定了该系统的饱和光功率约为3.2 mW. 在10 Hz–400 kHz的频率范围内, 系统的共模抑制比平均为55 dB, 在100 Hz处高达63 dB, 对激光经典技术噪声具有很强的抑制作用. 当入射光功率为400 μ W 时, 真空涨落噪声达到11 dB. 此低频量子真空噪声探测系统可广泛应用于量子计量和量子光学等研究领域.     

Low volatile monofunctional reactive diluents for radiation curable formulations

In the last decades the importance of UV curable formulations has increased continuously. Their fast curing speed, solvent-free polymerization conditions, and the formation of hard and highly crosslinked photopolymer networks represent major benefits. Commercial UV resins generally consist of multi-functional vinyl oligomers, photoinitiators, additives, and reactive diluents. Mono- and multi-functional reactive diluents serve as thinners to lower the overall resin viscosity and to improve processability. However, many monofunctional reactive diluents like isobornyl (meth)acrylate or benzyl (meth)acrylate exhibit high volatility, often already at room temperature. This causes adverse effects such as unpleasant odor, potential health risks, and changing resin composition during processing. A new group of monomers that show high potential for replacing traditional highly volatile reactive diluents are salicylate (meth)acrylates. In this work, salicylate-based thinners are synthesized, polymerized, and characterized with respect to their viscosity, volatility, thermal stability, photoreactivity, and thermomechanical properties of their homopolymers. Additionally, a first example of their diluting effect in a highly viscous difunctional polyester urethane methacrylate is demonstrated with 30 wt% of a cycloaliphatically and an aromatically substituted salicylate methacrylate. The polymers of the diluted resin exhibit similarly high glass transition temperatures of 110 and 126 °C, which are in the range of the polymers of the undiluted resin.     

二硫化锡纳米片阻变存储器的制备与性能

采用水热法合成了尺寸为50~100 nm的二硫化锡纳米片,并首次以二硫化锡作为阻变层材料的阻变存储器（Cu/PMMA/SnS₂/Ag,PMMA=聚甲基丙烯酸甲酯）,对其阻变性能进行了研究。结果表明： Cu/PMMA/SnS₂/Ag阻变存储器的开关比约10⁵,耐受性2.7×10³。在上述2项性能指标达到较优水平的同时,开态与关态电压分别仅约为0.28与-0.19 V。     

Microwave absorbing properties of Fe3O4–poly(3, 4‐ethylenedioxythiophene) hybrids in low‐frequency band

A facile method is proposed to obtain microwave absorbing materials (MAMs), which possess strong microwave absorption properties in low‐frequency range. By simply mechanical mixing, the obtained Fe₃O₄–poly (3,4‐ethylenedioxythiophene) (PEDOT) hybrids exhibit more excellent microwave absorbing properties than that of Fe₃O₄ or PEDOT individually. The analysis on the microwave absorbing properties of the Fe₃O₄–PEDOT hybrids indicates that the excellent microwave absorbing properties are ascribed to several factors, like the dielectric loss, the interface polarization, eddy current effect, natural ferromagnetic resonance, and the impedance as well as the thickness of the coating. The Fe₃O₄–PEDOT hybrids with appropriate mass ratios of PEDOT to Fe₃O₄ (represented by (PEDOT)/(Fe₃O₄)) show superior microwave absorbing property at low frequency. When the thickness is 4 mm, the reflection loss of the sample reached ?15.8 dB at 3.2 GHz with (PEDOT)/(Fe₃O₄) of 3 and ?31.4 dB at 4.5 GHz with (PEDOT)/(Fe₃O₄) of 2, respectively. The obtained Fe₃O₄–PEDOT MAMs will have a promising application in the practical industry and commerce affairs. Copyright © 2013 John Wiley & Sons, Ltd.     

Reactions in Nitroimidazole Triggered by Low‐Energy (0–2 eV) Electrons: Methylation at N1‐H Completely Blocks Reactivity

Low‐energy electrons (LEEs) at energies of less than 2 eV effectively decompose 4‐nitroimidazole (4NI) by dissociative electron attachment (DEA). The reactions include simple bond cleavages but also complex reactions involving multiple bond cleavages and formation of new molecules. Both simple and complex reactions are associated with pronounced sharp features in the anionic yields, which are interpreted as vibrational Feshbach resonances acting as effective doorways for DEA. The remarkably rich chemistry of 4NI is completely blocked in 1‐methyl‐4‐nitroimidazole (Me4NI), that is, upon methylation of 4NI at the N1 site. These remarkable results have also implications for the development of nitroimidazole based radiosensitizers in tumor radiation therapy.     

硫脲络合–火焰原子吸收光谱法测定低硅铝合金中的银含量

采用硫脲络合–火焰原子吸收光谱法测定低硅铝合金中的银元素含量。实验探讨了酸度及硫脲用量对银测定的影响及铝合金中基体元素与共存元素对银元素分析线的干扰情况。结果表明:选用9%的盐酸和3%的硝酸溶解试样最好,加入5 mL 50 g/L硫脲溶液可消除氯离子对试验结果的影响,基体铝元素和其它共存元素不干扰银的测定。根据低硅铝合金中银元素的含量范围,合成系列标准溶液,建立工作曲线,工作曲线的线性范围为0.05%~0.50%。银元素含量为0.30%的样品测定结果的相对标准偏差为0.15%(n=8),标准加入回收率为96.8%~98.5%。该方法操作简便、重现性好、测量结果准确可靠。     

高频燃烧–红外吸收法测定低合金钢中的碳含量

采用高频红外碳硫分析仪测定低合金钢中的碳含量。分别考察了取样量、助熔剂种类、助熔剂用量对测量结果的影响。结果显示当取样量为400 mg、钨助熔剂用量为样品取样量的1.2倍时,测定低合金钢中的碳含量效果最好,测定结果的相对标准偏差为0.9%(n=10),加标回收率在97.5%~102.7%之间。     

Single-Atom Electrocatalysts from Multivariate Metal–Organic Frameworks for Highly Selective Reduction of CO2 at Low Pressures

Single-atom catalysts (SACs) are of great interest because of their ultrahigh activity and selectivity. However, it is difficult to construct model SACs according to a general synthetic method, and therefore, discerning differences in activity of diverse single-atom catalysts is not straightforward. Herein, a general strategy for synthesis of single-atom metals implanted in N-doped carbon (M₁-N-C; M=Fe, Co, Ni and Cu) has been developed starting from multivariate metal–organic frameworks (MOFs). The M₁-N-C catalysts, featuring identical chemical environments and supports, provided an ideal platform for differentiating the activity of single-atom metal species. When employed in electrocatalytic CO₂ reduction, Ni₁-N-C exhibited a very high CO Faradaic efficiency (FE) up to 96.8 % that far surpassed Fe₁-, Co₁- and Cu₁-N-C. Remarkably, the best-performer, Ni₁-N-C, even demonstrated excellent CO FE at low CO₂ pressures, thereby representing a promising opportunity for the direct use of dilute CO₂ feedstock.     

Adaptive nematic liquid crystal lens array with resistive layer

ABSTRACT

We propose an adaptive nematic liquid crystal (LC) lens array using a dielectric layer with low dielectric constant as resistive layer. With the resistive layer and periodic-arranged iridium tin oxide (ITO) electrodes, the vertical electric field across the LC layer varies linearly over the lens aperture is obtained in the voltage-on state. As a result, a centrosymmetric gradient refractive index profile within the LC layer is generated, which causes the focusing behaviour. As a result of the optimisation, a thin cell gap which greatly reduces the switching time of the LC lens array can be achieved in our design. The main advantages of the proposed LC lens array are in the comparatively low operating voltage, the flat substrate surface, the simple electrodes, and the uniform LC cell gap. The simulation results show that the focal length of the LC lens array can be tuned continuously from infinity to 3.99 mm by changing the applied voltage.