Chromate leaching from inhibited primers: Part I. Characterisation of leaching

Leaching and characterisation studies have been undertaken on two chromate-inhibited epoxy polyamide primers. Leaching was carried out in 5% (w/v) NaCl solutions at different pH values (1, 3, 5 and 7) and the amount of Cr released into solution was monitored over time. Cr release was initially high, but as the immersion time increased the leaching from the primers slowed. Prior to and after immersion, the primers were characterised by a number of techniques including electron microprobe analysis, X-ray microdiffraction, Raman spectroscopy, and positron annihilation lifetime spectroscopy. The unexposed primers were found to contain the inorganic phases SrCrO₄, BaSO₄ and TiO₂ (anatase or rutile). Upon immersion, water uptake by the primers was observed, together with a decrease in the amount of SrCrO₄ in the primers. These studies provide insights into the mechanism of chromate leaching from inhibited primers.     

Microsatellite markers for Rhyzopertha dominica (Coleoptera: Bostrichidae)

Rhyzopertha dominica (F.) is a destructive insect pest of stored products. Due to this pest's broad host range, short life cycle, and high reproductive capacity, it has rapidly spread throughout the world. Understanding the population structuring of this important pest is vital for developing and implementing an effective integrated pest management strategy. In this study, we isolated 19 novel polymorphic microsatellite loci from an enriched genomic library based on a biotin/streptavidin capture protocol. The genetic parameters were estimated based on 80 individual R. dominica from two natural populations. The numbers of alleles ranged from 3 to 10, and sixteen loci exhibited polymorphic information contents (PICs) greater than 0.5. The observed (H_O) and expected (H_E) heterozygosities ranged from 0.033 to 0.900 and 0.310 to 0.882, respectively. Six locus/population combinations significantly deviated from Hardy–Weinberg equilibrium (HWE). These microsatellite markers will provide a valuable resource for studying the population genetic structure of this species.     

3组常见马源性成分鉴定引物特异性和灵敏度比较

比较筛选基于聚合酶链式反应(polymerase chain reaction, PCR)技术的马源性成分鉴定方法中高灵敏度和特异性引物。方法 选取来自国标法、专利和文献报道的3组马源性成分鉴定引物, 比较其灵敏度和特异性, 筛选高灵敏度和特异性引物。结果 3组引物的灵敏度和特异性存在差异, 以线粒体DNA为靶标的Ⅱ组马源性成分鉴定引物的特异性和灵敏度优于分别以线粒体和核基因组DNA为靶标的马驴通用鉴定引物, 检出最低限度均满足检测需求。结论 通过比较马源性成分鉴定的3组PCR引物, 以线粒体DNA为靶标的Ⅱ组马源性成分特异性鉴定引物可作为马成分鉴定的首选, 线粒体和核基因组靶标联合可提高马成分鉴定的准确性并可用于杂交种鉴定, 为马源性成分及产制品鉴定提供了一定基础。     

Diffusion of adhesion promoting and crosslinking additives in an uncured silicone sealant

A method has been devised for measuring the diffusion coefficient D of additives that act as adhesion promoters and crosslinking agents in uncured silicone sealants. This has been used to measure D for tetra-t-butyltitanate (TBT) and isobutyltrimethoxysilane (BTMS) in a sealant at 25°C. The value of D for TBT was found to be constant but that for BTMS decreased with the duration of the experiment, possibly due to the interaction of the silane with the silica particles.     

Covalent bonding of wood through chemical activation

The reaction of softwood thermomechanically pulped fibres with succinic anhydride (SA) and its subsequent reaction with hexamethylene diamine (HMDA) were examined, the latter employing the coupling agents dicyclohexylcarbodiimide, or diisopropylcarbodiimide. FTIR and ¹³C NMR studies showed amide linkages were produced between SA modified fibres and the diamine. Wood veneers were covalently bonded using this technology. It was found that during hot pressing bonding occurs between SA treated veneers and HMDA without the need for a coupling agent.     

The use of statistical experimental design procedures in the development and “robust” manufacture of a water-based, corrosion-inhibiting adhesive primer

Details of the statistical experimental design techniques used to prepare a robust, water-based, corrosion-inhibiting, adhesive primer of low toxicity are given and the results are used to illustrate the efficacy of the approach to both manufacture and performance of the end product.     

Influence of fluorescent dye on mechanical properties of adhesive systems

The aim of the study was to evaluate the influence of fluorescent dye (rhodamine B) on the ultimate tensile strength (UTS), elastic modulus (E), and flexural strength (FS) of different adhesives, specifically Scotchbond Multi-Purpose (3M ESPE, St. Paul, USA) and Clearfil SE Bond (Kuraray Medical Inc., Okayama, Japan). The bond of adhesive systems were mixed or not with 0.16 mg/mL of rhodamine B. The UTS values of beam-shaped specimens were measured with a universal testing machine (n=10). The FS and E values were evaluated with bar-shaped specimens (n=5). Data were statistically analyzed by two-way analysis of variance. No significant differences in UTS, E, or FS were found among the groups. Thus, at the concentration tested, incorporation of rhodamine B did not affect the mechanical properties of the adhesives.     

Species identification and phylogenetic relationships among five species of psocids from Chinese herbal medicines

The main objectives of the study were to establish an accurate multiplex PCR identification technique for five species of psocids from Chinese herbal medicines and to discuss the phylogenetic relationships among those species. Five species of booklice (Liposcelis bostrychophila, L. entomophila, L. tricolor, L. pearmani and L. rufa) were collected from Chinese herbal medicines. Genomic DNA of individual booklice was obtained via a nondestructive DNA extraction method. The internal transcribed spacer (ITS)1-5.8S-ITS2 gene sequences were obtained by PCR amplifying and sequencing. The primers were designed, and the phylogenetic trees were constructed using the NCBI website and MEGA software. In this research, a Multiplex PCR identification technique was established based on the ITS2 gene for the five species of booklice. The phylogenetic relationships among the five booklice species were analyzed and discussed based on the ITS gene sequences.     

Adhesion of thermoplastic polyurethane elastomer to galvanized steel

When a thermoplastic polyurethane elastomer (TPU) is co-molded with galvanized steel, the subsequent adhesion and its durability are very sensitive to the chemical bonds created at the interface. Silane coupling primers are known for enhancing adhesion between inorganic substrates and several polymers and this study addresses their efficiency at the TPU–metal interface. γ-APS aminosilane was deposited with different parameters, including pH and solvents. Several other surface treatments were studied for comparison: degreasing, corona discharge, acidic etching, gas flame, and a zinc phosphate conversion coating. The adhesion was characterized with a single wire pull-out test derived from the microbond test geometry, after different aging conditions. Results confirmed that γ-APS worked as a coupling agent in between TPU and the inorganic substrate, outperforming all other surface treatments tested in term of strength and durability, but the silane required the appropriate deposition parameters to be really efficient.In parallel, a finite element approach was proposed for the modeling of fiber reinforced thermoplastic elastomer composites accounting for the non-linear viscoelastic material properties and its results compared to an analytical elastic shear-lag interpretation of the single filament pull-out test. The analytic interpretation was found to be sufficiently accurate for stress analysis but not for fracture mechanics. The FEM analysis offered an evaluation of the internal stresses developed within the entire system, which helped the interpretation of results. The model, compared to experimental results, also revealed that it is important to account for internal stresses, mostly for treatments leading to low intrinsic interfacial shear strength values.     

Paint systems formulated with ion-exchange pigments applied on carbon steel: Effect of surface preparation

Ion exchange pigments are a scientifically very interesting alternative to chromates that have not yet been fully explored. This study considers the following candidate anticorrosive pigments: calcium-exchanged silica (Si/Ca), hydrotalcite/vanadate (HT/V) and calcium bentonite (Bentonite/Ca).