Effect of solid walls on spontaneous wave formation at water/oil interfaces

The regulation of spontaneous waves at water/oil interfaces was investigated, focusing on effects of materials and sizes of containers. Trimethylstearylammonium chloride was dissolved in an aqueous phase. Nitrobenzene with potassium iodide and iodine was used as an organic phase. Rotation of interfacial waves with almost triangular shape was observed only in containers made of glass. The nature of interfacial waves is sensitive to container size. There was no interfacial wave in PFA (Teflon) containers. However, when a glass plate was soaked vertically to the interface, oscillation of contact angles of water/oil interfaces to glass plates was observed. The oscillation generated wave propagation along the plate. Dynamic interfacial tension was measured by Wilhelmy method and the pendant drop technique. Results with the Wilhelmy method in small glass containers exhibited spontaneous oscillation. However, oscillations in dynamic interfacial tension were not observed for other cases, i.e., the Wilhelmy method for large glass containers, for PFA containers, and for the pendant drop technique. It was concluded that all nonlinear behavior such as wave generation and apparent tension oscillation could be attributed to the effect of the sidewalls of container on the adsorption/desorption kinetics of the surfactant. We propose a possible scenario which can explain all of the qualitative features of the present experimental findings.     

Spatially controlled chemistry using remotely guided nanoliter scale containers

In this communication we describe a new chemical encapsulation and release platform using 3D microfabricated nanoliter scale containers with controlled porosity. The containers can be fabricated of magnetic materials that allow them to be remotely guided using magnetic fields. The favorable attributes of the containers that include a versatile highly parallel fabrication process, precisely engineered porosity, isotropic/anisotropic chemical release profiles, and remote magnetic guiding provide an attractive platform for engineering spatially controlled chemical reactions in microfluidic systems.     

Analysis of Microplastics in Takeaway Food Containers in China Using FPA-FTIR Whole Filter Analysis

With the rapid development and popularization of the internet and smartphone industry for ordering and delivery, the consumption of takeaway food is increasing globally, especially in China. However, there is little information about microplastics in takeaway food containers, so their potential risks to human health remain unknown. This study explored the possibility of using focal plane array (FPA)-based micro-FT-IR imaging to detect microplastics released from food containers and evaluated their contents using an automated database matching analysis method. We investigated microplastics in seven types of food containers widely used in China. The most common plastic types observed were polyamide (PA), polyurethane (PU) and polystyrene (PS), which were found to comprise 22.8%, 18.2%, and 8.5% (number of particles) of all microplastics, respectively. Microplastics were found in all seven types of food containers, and the content excluding cellulose was 29–552 items/container. Our research shows that microplastics in takeaway food containers might originate from atmospheric sediment or flakes from the inside surface of the container. According to the content of microplastics in takeaway food containers, people who order takeaway food 5–10 times a month might consume 145–5520 microplastic pieces from food containers.     

Analysis and stability of mercury speciation in petroleum hydrocarbons

Raw petroleum and natural gas often contain high concentrations of mercury, which can be damaging to the metal components of production facilities, as well as to the environment. Various Hg species have different properties in terms of mobility, reactivity and bioavailability. Thus, for cost-effective decisions regarding plant design, Hg extraction, and pollution control, speciation information must be available at the production facility. In this paper, a simple, wet chemical speciation method, which provides data on Hg^o, dissolved and particulate total Hg, Hg(II), and methyl Hg is presented. The method incorporates species-specific extraction and separation procedures, followed by cold vapor atomic fluorescence spectrometry (CVAFS). For each species, detection limits of approximately 0.1 ng/g were obtained. Storage experiments in various containers showed that organo-mercury species were stable for at least 30 days in all containers except those made of polyethylene; and Hg^o was stable in all containers except those made of stainless steel or polyethylene. Hg(II) was rapidly lost from all containers except those made of aluminum, which rapidly converted it to Hg^o, which was stable. In general, most of the total Hg in petroleum products was particulate Hg, followed by dissolved Hg(II) and Hg^o. Sub-ng/g concentrations of methyl-Hg were observed in most samples. Received: 4 June 1999 / Revised: 18 October 1999 / Accepted: 22 October 1999     

Analysis and stability of mercury speciation in petroleum hydrocarbons

Raw petroleum and natural gas often contain high concentrations of mercury, which can be damaging to the metal components of production facilities, as well as to the environment. Various Hg species have different properties in terms of mobility, reactivity and bioavailability. Thus, for cost-effective decisions regarding plant design, Hg extraction, and pollution control, speciation information must be available at the production facility. In this paper, a simple, wet chemical speciation method, which provides data on Hg(o), dissolved and particulate total Hg, Hg(II), and methyl Hg is presented. The method incorporates species-specific extraction and separation procedures, followed by cold vapor atomic fluorescence spectrometry (CVAFS). For each species, detection limits of approximately 0.1 ng/g were obtained. Storage experiments in various containers showed that organo-mercury species were stable for at least 30 days in all containers except those made of polyethylene; and Hg(o) was stable in all containers except those made of stainless steel or polyethylene. Hg(II) was rapidly lost from all containers except those made of aluminum, which rapidly converted it to Hg(o), which was stable. In general, most of the total Hg in petroleum products was particulate Hg, followed by dissolved Hg(II) and Hg(o). Sub-ng/g concentrations of methyl-Hg were observed in most samples.     

Sonochemical Synthesis of Magnetic Protein Container for Targeted Delivery

A new targeted delivery system was developed in this paper by depositing magnetic NPs on protein containers which were prepared by sonicating oil in a protein solution. The deposition was conducted by layer‐by‐layer technique and monitored by zeta potential measurement. Such prepared samples can be targeted delivery in an external magnetic field. The hydrophobic dye TPP, as a model of drug, was loaded in the containers by dissolution in the oil phase before sonication. The containers loaded with dye are stable and can sustain the deposition treatment without loss of dye due to the protection of protein nanoshells.

     

A clean laboratory for ultralow concentration heavy metal analysis

Summary Laboratory facilities and methods are described which have been developed in our laboratory in collaboration with C. Patterson's group at the California Institute of Technology for the reliable measurement of various heavy metals at extremely low concentration levels down to the sub pg/g level in Antarctic and Greenland snow and ice. All analytical work is performed inside a clean laboratory pressurized with air filtered through high efficiency particle air filters and equipped with all-plastic laminar flow clean benches. High-purity water is produced by ion-exchange resins, and high purity acids from the US National Institute of Science and Technology are used. The various containers which are in contact with the samples are made of conventional low density polyethylene and FEP teflon. These containers are cleaned by immersion during several weeks in a succession of heated acid baths of increasing purity. Extremely careful blank determinations are made in order to quantitatively determine how much of the investigated metals is added to the samples from each separate reagent, from the walls of the various containers and from the air of the clean laboratory.     

Synthesis of polyaniline‐modified mesoporous‐silica containers for anticorrosion coatings via in‐situ polymerization and surface‐protected etching

An efficient type of container for anticorrosion coating based on polyaniline (PANI) modified mesoporous silica (pS) sphere has been first prepared via in‐situ polymerization and surface‐protected etching. The PANI‐modified containers not only show higher concentration of loaded inhibitor than pS, but also protect steel well because of the PANI. The coating with 1H‐benzotriazole (BTA) loaded containers shows significant anticorrosion property because of the release of BTA from containers. The structure and morphology of container are characterized by FTIR, XRD, SEM and TEM. The release of BTA from pS and PANI‐modified containers is determined by UV in water. The possible self‐healing anticorrosion performances are evaluated by EIS and polarization curves which indicate that the coating including BTA‐loaded containers performs best. The strategy of modifying pS by PANI is effective and successful. Copyright © 2016 John Wiley & Sons, Ltd.     

Use of aluminum containers in the determination of oxygen in organic substances by elemental microanalysis

The possibility of using cheap aluminum containers in oxygen elemental microanalysis of organic substances was studied. The absolute values of oxygen retention displayed by aluminum containers, as compared with silver ones, for CH(N)O(S)(Br) substances are shown. The magnitude of retention due an aluminum container is reproducible under given conditions. The precision and accuracy of the results of oxygen determination in CH(N)O compounds pyrolyzed in aluminum containers at 980 °C do not differ from the precision and accuracy of the results obtained with the use of silver containers.     

Systematic Errors in the Determination of Trace Metals by GFAAS Technique,Part I

The behaviour of solutions containing 7 metals in trace range (pH=2) prepared in borosilicate glass and polyethylene containers and transferred into commercial polyethylene–polypropylene and home-made quartz autosampler cups for measurements were studied using graphite furnace atomic absorption spectrometry. The different interactions between metal solution and vessel material were observed for the metals studied. The most significant losses of chromium and nickel occurred on a polyethylene surface, while the highest absorbance signals were registered from quartz containers. Higher absorbance signals from quartz containers were also obtained for cadmium and copper solutions. Contrary to these results, the absorbance signals for lead solutions were lowest when measured from quartz vessels. The container material had no influence on the analytical signals of cobalt and manganese.Received January 15, 2003; accepted April 15, 2003 published online August 22, 2003     

Quantitation of free and total bisphenol A in human urine using liquid chromatography-tandem mass spectrometry

Bisphenol A (BPA) is employed in the synthesis of polycarbonate plastics and epoxy resins and is widely used in consumer products including as a coating for the inside of almost all food and beverage containers and thermal-imaging paper. Bisphenol A is considered to have important health implications because it possesses weak estrogenic activity and can leach from storage containers resulting in its consumption by both humans and animals. It is metabolized in the body and excreted into urine as a glucuronide derivative. In this report, we present an accurate, selective, sensitive, and reproducible high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) method for the quantitation of BPA in human urine, which is not prone to exogenous contamination. BPA-glucuronide is hydrolyzed enzymatically, extracted with toluene, derivatized with dansyl chloride, and the BPA-(dansyl)(2) derivative is analyzed using reversed-phase HPLC/MS/MS. Calibration was linear to 50 ng/mL with a limit of quantitation of 50 pg/mL and a limit of detection of 5 pg/mL.     

HG-AAS法测定不锈钢食具浸泡液中的砷

研究了利用氢化物发生原子吸收法测定不锈钢食具浸泡液中痕量砷的反应体系.对载气流速、硼氢化钠溶液的浓度、5％抗坏血酸-5％硫脲溶液添加量和介质酸度的影响,以及基体和共存离子的干扰等条件进行了研究.样品加标回收率为95.8％～106.2％,测定结果的相对标准偏差不大于2.8％,方法检出限为0.12 μg/L.该方法适用于不...     

Potential of solid phase microextraction and gas chromatography for quarantine-required detection of wood packaging in shipping containers

Solid phase microextraction (SPME) coupled with gas chromatography (GC) was used to detect terpene hydrocarbons inside shipping containers entering New Zealand. The utility of this system for the rapid detection of undeclared wood packaging for quarantine purposes was demonstrated. A portable dynamic air-sampling device was built to house a SPME fibre and allow the air from shipping containers to be sampled. The effects of sample flow rate and sampling time were investigated and sampling conditions of 100 mL/min for 30 s were chosen to keep sampling within the linear range. A CV of less than 15% (n = 12) was obtained for all the compounds analysed under these conditions. To obtain an estimate for the limit of detection (LOD) for the terpene hydrocarbons of interest, small quantities of lime oil were placed in an empty shipping container and the air inside was analysed. LOD (S/N = 3) was estimated to be in the order of 50-100 ng/L of air using GC with flame ionisation detection (GC-FID). Finally, the device was tested in fully laden containers and was shown to be effective for trapping terpene hydrocarbons indicative of wood packaging.     

Acid‐Labile Acyclic Cucurbit[n]uril Molecular Containers for Controlled Release

Stimuli‐responsive molecular containers are of great importance for controlled drug delivery and other biomedical applications. A new type of acid labile acyclic cucurbit[n ]uril (CB[n ]) molecular containers is presented that can degrade and release the encapsulated cargo at accelerated rates under mildly acidic conditions (pH 5.5–6.5). These containers retain the excellent recognition properties of CB[n ]‐type hosts. A cell culture study demonstrated that the cellular uptake of cargos could be fine‐tuned by complexation with different containers. The release and cell uptake of cargo dye was promoted by acidic pH.     

Acyclic cucurbit[n]uril molecular containers selectively solubilize single-walled carbon nanotubes in water

Making single-walled carbon nanotubes (SWNTs) soluble in water is a challenging first step to use their remarkable electronic and optical properties in a variety of applications. We report that acyclic cucurbit[n]uril molecular containers 1 and 2 selectively solubilize small-diameter and low chiral angle SWNTs. The selectivity is tunable by increasing the concentration of the molecular containers or by adjusting the ionic strength of the solution. Even at a concentration 1000 times lower than typically required for surfactants, the molecular containers render SWNTs soluble in water. Molecular mechanics simulations suggest that these C-shaped acyclic molecules complex the SWNTs such that a large portion of nanotube sidewalls are exposed to the external environment. These "naked" nanotubes fluoresce upon patching the exposed surface with sodium dodecylbenzene sulfonate.     

The issue of contamination in recycling

This paper describes a model study aimed at establishing the main contamination issues for material recycling of HDPE blow-moulded containers. Detergent, bleach, lubricating oil and white spirit containers purchased from retailers have been recycled separately. Both atmospheric contamination during recycling, and the presence of contaminants in the recycled pellets and containers, have been measured. Standard washing and extrusion procedures were used with no attempt to optimise the treatment at this stage. The main contaminants found in the recycled bottles were oil and white spirit (both up to 0.6% by weight). Small amounts of chlorine (from bleach), limonene (from detergent) and oil additives were also found in the reprocessed pellet.     

How accurate must a reference material be?

 This article deals with reference materials (RMs) used for calibration purposes. For most common spectroscopic and chromatographic methods, RMs which have a relative content uncertainty of up to 3% can be used without considerably increasing the overall measurement uncertainty of the complete procedure. It is vital that the correct amount of the RM is used to ensure the quality of the quantitative chemical analyses. This can only be guaranteed if, in addition to the correct determination of the amount, the stability of the RM in the sales packaging is considered in the quoted uncertainty. For instance when the RM is packed in a container made of polyvinylidene fluoride water losses in hot climates can result in an increase in concentration which cannot be neglected. This is also true for high density polyethylene containers (PE-HD) although to a lesser degree. When mercury solutions of 1000 mg/l to 10 000 mg/l are kept in diluted nitric acid in PE containers, a relevant reduction in amount can be measured despite the water losses. However, the solutions remain stable in glass containers.     

Biadhesive Peptides for Assembling Stainless Steel and Compound Loaded Micro‐Containers

Biadhesive peptides (peptesives) are an attractive tool for assembling two chemically different materials—for example, stainless steel and polycaprolactone (PCL). Stainless steel is used in medical stents and PCL is used as a biodegradable polymer for fabrication of tissue growth scaffolds and drug delivering micro‐containers. Biadhesive peptides are composed of two domains (e.g., dermaseptin S1 and LCI) with different material‐binding properties that are separated through a stiff peptide‐spacer. The peptesive dermaseptin S1‐domain Z‐LCI immobilizes antibiotic‐loaded PCL micro‐containers on stainless steel surfaces. Immobilization is visualized by microscopy and field emission scanning electron microscopy analysis and released antibiotic from the micro‐containers is confirmed through growth inhibition of Escherichia coli cells.     

Screening adulteration of polypropylene bottles with postconsumer recycled plastics for oral drug package by near-infrared spectroscopy

Adulteration of pharmaceutical packaging containers with postconsumer recycled plastic materials was considerably difficult to identify due to the similar chemical compositions of virgin and recycled plastics. In the present study, near-infrared (NIR) spectroscopy coupled with conformity test was proposed to screen the adulteration of pharmaceutical packaging containers. Two kinds of representative screening models were investigated on polypropylene (PP) bottles for oral drug package. The reliability of the screening models was validated through studying the identification reliability, specificity, and robustness of the methods. The minimum spiking level of two modeled adulterants at the proportion of 20% could be detected, and the unqualified sample from a domestic manufacturer was rejected by this developed method. This strategy represents a rapid and promising analytical method for screening the adulteration of pharmaceutical plastic packaging containers with postconsumer recycled plastics.     

PEG-Chitosan as a Perspective Stabilizing Agent for Liposomal Suspensions: The Influence of the Molecular Weight and Degree of PEGylation on the Physicochemical Properties of the Complex

The possibility of regulating the physicochemical properties (stability, size, and binding sites) of liposomal containers for drug delivery by selecting the molecular weight and degree of modification of PEG-chitosan is demonstrated. The effect of the regulation of the release of doxorubicin from liposomal containers depending on the properties of the polymer and pH is demonstrated.