Plasma ignition threshold disparity between silver nanoparticle-based target and bulk silver target at different laser wavelengths

Plasma ignition threshold of nanoparticle-based and bulk silver targets was measured in air. The plasma was initiated by a Nd:YAG laser at wavelengths of 355, 532, and 1064 nm. The plasma ignition was monitored utilizing the prominent Ag I line at 546.5 nm. Lower ignition thresholds of the nanoparticle-based silver target were estimated at 0.4?±?0.02, 0.34?±?0.04, and 0.27?±?0.035 J cm~(-2) coupled with the different laser wavelengths, respectively. In contrast, the bulk silver target plasma exhibited an order of magnitude higher ignition threshold. A three orders of magnitude enhanced emission intensity from the nano-based target over the bulk target was achieved at lower levels of laser irradiation. A reduction of the thermal diffusion length of the nanosilver was assumed in order to theoretically predict this reduction in the plasma threshold. In addition, the effect of self-reversal on the resonance lines was taken into consideration.     

全涤珊瑚绒针织物纳米银抗菌整理技术

介绍了一种纳米银多巴胺固体微球的乳液的制备方法,以及这类乳液在全涤珊瑚绒针织面料的长效抗菌整理中的应用。本研究采用环氧丙烷与环氧乙烷的共聚物Pluronic F-127作为还原剂和分散剂,负载纳米银离子,然后通过熔融喷涂,将负载纳米银离子的Pluronic F-127微球用石蜡保护起来,最后和多巴胺复配．配制成用于全涤珊瑚绒针织面料的抗菌整理乳液。实验结果表明,经这类纳米银多巴胺固体微球的乳液处理的全涤珊瑚绒针织面料具有优异的耐久抗菌效果。     

超声引发乳液聚合同步原位合成纳米Ag/聚合物复合粒子的研究

超声辐射不含引发剂、还原剂而仅含有银盐的甲基丙烯酸甲酯乳液,原位合成了纳米Ag/PMMA复合粒子。这种复合粒子的IR、HRTEM和TEM表征结果显示,以纳米银为核的复合粒子具有很好的分散性,且纳米银为多晶体,纳米银粒子与聚合物间存在化学作用。通过考查反应过程中各因素对单体转化率的影响发现：不存在AgNO3时MMA几乎不聚合,而加入AgNO3时MMA不但能聚合,而且在一定浓度范围内,转化率随AgNO3浓度增加而增大说明银离子的存在能够促进单体的聚合。纳米Ag/PMMA复合物的热分析实验结果表明,银粒子的存在可能催化复合材料中PMMA的分解,导致分解温度提前。     

Nanosilver Migrated into Food‐Simulating Solutions from Commercially Available Food Fresh Containers

Manufacturers of food fresh containers use nanosilver as an antimicrobial agent, but the safe impacts of nanosilver release from commercial products are unknown. The nanoparticles that migrate from the consumer products should be determined to assess the safety and/or risks of nanotechnology. This paper describes experimental work carried out on one kind of commercial food fresh container (polyethylene plastic bags). In the experiments, the range of temperatures was from room temperature (about 25°C) to 50°C, the range of time intervals was from 3 to 15 days, and the bags were filled with four kinds of food‐simulating solutions representing water, acid, alcohol and fatty foods, respectively. Microwave digestion method was used for sample pre‐treatment. The scanning electron microscopy and energy‐dispersive X‐ray (SEM/EDX) analysis was used to confirm the presence and morphology of nanosilver additives, and the atomic absorption spectroscopy (AAS) analysis was applied, showing that the commercial bags contained 100 μg (Ag)/g (plastic materials). Strong evidences from SEM/EDX and AAS analyses were found, indicating the migration of nanosilver from the polyethylene bags into food‐simulating solutions. The amount of nanosilver migration was observed as increasing with storage time and temperature. Copyright © 2011 John Wiley & Sons, Ltd.     

An Integrated Approach Toward Renewable Energy Storage Using Rechargeable Ag@Ni0.67Co0.33S‐Based Hybrid Supercapacitors

Self‐powered charging systems in conjunction with renewable energy conversion and storage devices have attracted promising attention in recent years. In this work, a prolific approach to design a wind/solar‐powered rechargeable high‐energy density pouch‐type hybrid supercapacitor (HSC) is proposed. The pouch‐type HSC is fabricated by engineering nature‐inspired nanosliver (nano‐Ag) decorated Ni_0.67Co_0.33S forest‐like nanostructures on Ni foam (nano‐Ag@NCS FNs/Ni foam) as a battery‐type electrode and porous activated carbon as a capacitive‐type electrode. Initially, the core–shell‐like NCS FNs/Ni foam is prepared via a single‐step wet‐chemical method, followed by a light‐induced growth of nano‐Ag onto it for enhancing the conductivity of the composite. Utilizing the synergistic effects of forest‐like nano‐Ag@NCS FNs/Ni foam as a composite electrode, the fabricated device shows a maximum capacitance of 1104.14 mF cm^?2 at a current density of 5 mA cm^?2 and it stores superior energy and power densities of 0.36 mWh cm^?2 and 27.22 mW cm^?2, respectively along with good cycling stability, which are higher than most of previous reports. The high‐energy storage capability of HSCs is further connected to wind fans and solar cells to harvest renewable energy. The wind/solar charged HSCs can effectively operate various electronic devices for a long time, enlightening its potency for the development of sustainable energy systems.     

Synthesis and properties of electrical conductive and antibacterial siloxane-modified carbon fiber–silver–acrylate nanocomposites

First, silanized carbon fiber (SCF) was synthesized, then silanized carbon fiber–silver (SCF-S) was obtained. Finally, silanized carbon fiber–silver–acrylate (SCF-S-A) electrical conductive and antibacterial composites were prepared. The structures of CF, SCF, SCF-S, and SCF-S-A were characterized by X-ray photoelectron spectroscopy, FTIR, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and UV spectra. The electrical conductive and antibacterial properties of SCF-S-A nanocomposites were studied. The results showed that electrical conductive and antibacterial activity properties of SCF-S-A nanocomposites were improved. When the content of SCF-S was 50%, the conductivity of SCF-S-A nanocomposites was maximum. The SCF-S-A nanocomposites will have promising application in high-performance electrical conductive and antibacterial materials.     

纳米银-聚乙烯复合包装中银对2 种抗氧化剂向食品模拟物迁移的影响

探究纳米银-聚乙烯复合包装中纳米银成分的存在对2 种抗氧化剂（Irganox1076和Irgafos168）向食品模拟物迁移规律的影响。将含有抗氧化剂的聚乙烯包装膜和同时含有抗氧化剂与纳米银的复合包装膜裁成正方形若干,分别浸泡于正己烷和体积分数95%乙醇溶液2 种食品模拟物中,密封后在20、40 ℃以及70 ℃条件下进行迁移实验。食品模拟物中2 种抗氧化剂的加标回收率在79.3%～108.0%之间,相对标准偏差在0.7%～5.3%之间。2 种抗氧化剂的迁移会随着迁移温度的升高以及迁移时间的延长而增加直至达到迁移平衡,且其在正己烷模拟物中的迁移量大于在体积分数95%乙醇模拟物中的迁移量;含纳米银聚乙烯塑料比不含纳米银聚乙烯塑料中的抗氧化剂向食品模拟物中的迁移量小,表明纳米银成分的存在可以抑制包装中的抗氧化剂向食品模拟物中的迁移。     

纳米银制备及提高生防菌剂抗菌活性

[目的]为有效克服传统生物农药有效成分吸收慢、药效持久性短和药效不稳定的弱点,对纳米银制备及提高生防菌抗菌活性进行了研究.[方法]利用化学液相还原法,在氨水存在的情况下,以抗坏血酸作为还原剂、聚乙烯吡咯烷酮作为保护剂,还原氨银溶液,制备纳米银;以番茄灰霉病菌和白菜软腐病菌为供试菌,进行纳米银与生防菌剂协同抗菌作用的研究.[结果]经富集、清洗、超声处理后得到的纳米银,扫描电子显微镜鉴定其平均粒径在100 nm以内,形状规则,纯度在90%以上;纳米银与硫酸链霉素对白菜软腐病菌的共毒系数为244.3,对大肠杆菌为315.4.[结论]纳米银可有效提高拮抗菌的拮抗活性,完全抑制灰霉病菌丝生长;其与硫酸链霉素结合可显著提高对白菜软腐病菌的抑制作用.     

纳米银-聚乙烯复合薄膜的制备及表征

目的探究以熔融共混方式制备的纳米银复合膜的性能。方法采取熔融共混,吹塑成膜方式制备含不同添加剂的纳米银-聚乙烯复合包装薄膜。使用扫描电镜表征纳米银粉末和纳米银-聚乙烯复合膜内银的粒径大小,并用傅里叶变换红外光谱对复合膜的化学键进行表征。探究纳米银以熔融共混的方式复合到聚乙烯内后,对薄膜颜色、透光性、氧气透过率、水蒸气透过率的影响。结果纳米银粉末和复合膜内的银均含不同粒径,纳米银的加入未产生明显的新化学键,薄膜的透光率降低了3.9%~12.2%,氧气透过率提高了6.56~117.17 cm~3/(m~2·d·(0.1 MPa)),水蒸气透过率提高了0.038~1.791 g/(m~2·d)。结论以熔融共混方式制备的纳米银-聚乙烯复合膜透光率下降,氧气透过率和水蒸气透过率得到提高,未形成明显的新化学键。     

Non‐Toxic Dry‐Coated Nanosilver for Plasmonic Biosensors

The plasmonic properties of noble metals facilitate their use for in vivo bio‐applications such as targeted drug delivery and cancer cell therapy. Nanosilver is best suited for such applications as it has the lowest plasmonic losses among all such materials in the UV‐visible spectrum. Its toxicity, however, can destroy surrounding healthy tissues and thus, hinders its safe use. Here, that toxicity against a model biological system (Escherichia coli) is “cured” or blocked by coating nanosilver hermetically with a about 2 nm thin SiO₂ layer in one‐step by a scalable flame aerosol method followed by swirl injection of a silica precursor vapor (hexamethyldisiloxane) without reducing the plasmonic performance of the enclosed or encapsulated silver nanoparticles (20–40 nm in diameter as determined by X‐ray diffraction and microscopy). This creates the opportunity to safely use powerful nanosilver for intracellular bio‐applications. The label‐free biosensing and surface bio‐functionalization of these ready‐to‐use, non‐toxic (benign) Ag nanoparticles is presented by measuring the adsorption of bovine serum albumin (BSA) in a model sensing experiment. Furthermore, the silica coating around nanosilver prevents its agglomeration or flocculation (as determined by thermal annealing, optical absorption spectroscopy and microscopy) and thus, enhances its biosensitivity, including bioimaging as determined by dark field illumination.