Mechanical and rheological properties of calcium carbonate-filled ethylene propylene diene elastomer reinforced by metallic acrylate salt

High performance ethylene propylene diene methylene elastomer (EPDM)/calcium carbonate (CaCO₃)/aluminum triacrylate (ALTA) hybrids have been prepared by a melt compounding process. The mechanical properties of the peroxide cured EPDM/CaCO₃/ALTA vulcanizates were investigated by tensile, hardness, resilience, abrasion and fatigue life tests. The results showed that the ALTA can greatly improve the modulus at 100 %, tensile strength, abrasion resistance and fatigue life of the EPDM/CaCO₃/ALTA vulcanizates, while retaining their high elongation at break. ALTA as a reactive filler had accelerating effect on the vulcanization reaction of and increased the crosslink density of the EPDM/CaCO₃ composites. This phenomenon is due to increasing the ionic bonds arise from both homo-polymerization of ALTA and graft co-polymerization of it onto the EPDM. Scanning electron microscopy (SEM) revealed the presence of ALTA causes to the roughness of the fracture surface of CaCO₃-filled EPDM compounds demonstrating high interaction between the fillers and EPDM improved by introduction of ALTA. Dynamic mechanical analysis revealed that the glass transition temperature (T _g ) and dissipation peak (tan δ) of EPDM composites decreases with increasing ALTA content. Decrease in tan δ value and inward shifting of T _g were related to improved interaction of filler and EPDM.     

Use of enzyme-linked immunosorbent assay to detect potato leafroll virus in field grown potato,cv. Russet Burbank

Use of enzyme-linked immunosorbent assay (ELISA) in detecting potato leafroll infections in field grown potato, cv. Russet Burbank, was studied from 1986 to 1988 at Rosemount, Minnesota. The objective was to determine relative reliability of current season foliage ELISA, tuber tissue ELISA, and tuber progeny foliage ELISA. Serological tests were most accurate when foliage of tuber progenies was tested. ELISA underestimated total leafroll infection when current season foliage from the inoculated plant was used, in those plants inoculated during late tuber bulking stage. Current season foliage ELISA tests using newly expanded terminal leaflets were more reliable than were tests using older leaflets. Leafroll infection was detected in the current season foliage and tuber progenies (tuber tissue as well as tuber progeny foliage) of some plants seven days after inoculation. Most current season foliage infections were detected by day 14–28 depending on year. Differences among years were most likely caused by variation in quality of virus source plants and numbers of vectors used in inoculation. ELISA tests on tuber tissue were almost as effective as ELISA tests on tuber progeny foliage in detecting potato leafroll 20 days after inoculation, but ELISA on tuber tissue substantially underestimated infection if plants were sampled earlier. Maximum percent tuber infection occurred 20 days or more after inoculation. Movement of the virus from the inoculated stem to other stems decreased with increased plant age at inoculation. Percent infected tubers declined with increased plant age at inoculation. Action thresholds developed for aphids in managing potato leafroll virus should take into account the temporal change in percent infected tubers.     

Analyzing the quasi-static puncture resistance performance of shear thickening fluid enhanced p-aramid composite

The quasi-static (QS) puncture resistance of p-aramid Twaron fabric impregnated with shear thickening fluid (STF) based on the molecular weight variation of the base liquid has been investigated. To synthesis the STF, the 12 nm silica particles have been dispersed in polyethylene glycol (PEG) with two different molecular weights, 200 and 400 g/mol by means of mechanical mixing. The weight percentages of silica particles in the continuous phase were selected as 15, 25 and 35 wt%. The results of rheological tests indicate that with the increase of the polymer’s molecular weight, the viscosity and instability of the suspension increase, while its critical shear rate diminishes. The STF impregnated Twaron fabrics were subjected to QS puncture resistance tests according to the ASTM standard D6264. The quasi-static puncture resistance increased about 4.5 fold for Twaron fabric impregnated with 35 wt% concentration STF relative to the neat Twaron. Also, with the increase of the PEG’s molecular weight in Twaron fabrics impregnated with 15 and 25 wt% concentration STFs, the QS puncture resistance of Twaron fabrics improved considerably, but it didn’t change too much in the Twaron fabric impregnated with 35 wt% concentration STF.     

Modeling the functional compression properties of hand-knotted carpets using factorial design and response surface methodology

The most performance quality of cut-pile carpets is related to mechanical behavior of surface piles under compression loading in use. In this study, main purpose was to achieve the predictive models of the functional compression properties of carpet including work of compression (WC), compressional resilience (RC), linearity of compression-thickness curve (LC), and thickness loss (TL) after recovery on hand-knotted carpets with symmetric (Turkish) knot. Eighteen hand-knotted carpet samples with different structural specifications were produced. Meanwhile, compression properties were investigated in new and worn out carpet samples by a Hexapod tumbler tester in 4000 and 12000 revolutions. Factorial experimental design and response surface method were applied for modeling of each compression properties. To optimize the initial models the Box-Cox transformation was used. In the final models, contribution of different variables was also determined. The models showed a desirable fit and high adjusted R² values were observed. The ANOVA test showed that the obtained models are valid at 5 % level significant.     

A study of surface morphology and structure of cotton fibres with soluble immobilized-cellulase treatment

Our previous studies have demonstrated that cotton fabrics treated with soluble immobilized-cellulase showed considerably lower degradation and higher retention of tensile strength than those treated with free cellulase. It is important to investigate the surface morphology and structure of cotton fibres for understanding the enzymatic degradation. In this study, the effects of the soluble immobilized-cellulase on the surface morphology and structure of cotton fibres were investigated. The ultrastructural changes in the fibre surfaces were inspected using Tapping-Mode Atomic Force Microscopy (TM-AFM) and scanning electron microscopy (SEM), and the results showed that the smooth surfaces could be obtained after the immobilized-cellulase treatment, and no obvious damage was observed on the fibre surfaces. The hydrogen bonds in the certain depth area beneath the fibre surface were investigated using Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR) after the cellulase treatments. Furthermore, the result of fibre accessibility indicated that the hydrolysis occurring in the interior of the cotton fibres was limited during the immobilized-cellulase treatment. Crystalline index (CI) of the cotton fibres treated with free cellulase was slightly higher than that of fibres treated with immobilized cellulase.     

Manufacturing technique and mechanical properties of polylactide acid net/chitosan composite membrane

Guided tissue regeneration is an important treatment for periodontal diseases, as it helps periodontal tissues to regenerate. This study aims to evaluate the influence of different procedures for gelation on the mechanical properties of low melting-point polylactic acid (LPLA) net/chitosan composite membranes. After immersion in a chitosan solution, LPLA nets undergo different steps of gelation and freeze-drying, forming the porous LPLA/Chitosan composite membranes. The tensile strength, swelling, degradation and water content of the resulting membranes are then evaluated. According to the experimental results, different sequences for gelation influence the tensile strength and swelling ratio, but do not significantly influence the water content ratio and contact angle.     

Molecular Analysis of Phytophthora infestans (Mont.) de Bary from Chapingo,Mexico. Phylogeographic Referential

An Andean origin of Phytophthora infestans was originally based on written records, and recently inferred from mitochondrial and nuclear gene genealogies, which emphasize a common South American origin of the European isolates, and absence of the I-b haplotype in Mexico (recently identified in Tlaxcala, Mexico). In order to compare such results, we sequenced the nuclear genes β-tubulin, Ras, and Intron Ras, and rDNA ITS regions in 24 P. infestans genotypes isolated, identified, and selected, during three crop growing cycles in Chapingo, Mexico. The pathogen showed homology and 100 % sequence similarities to the ones reported for the Andes and Europe β-tubulin, Ras, and Intron Ras genes. Results for the ITS region were inconclusive. The molecular oomycete similarities from the three geographical regions (South America, Europe, and Mexico), and the Mexican genotypes characteristics reported in the species supports the hypothesis of the location of P. infestans diversity and a center of dispersal in the central highlands of Mexico.     

Potato leafroll virus purification and antiserum preparation for enzyme-linked immunosorbent assays

Potato leafroll virus (PLRV) was purified from potato foliage and stems with an average yield of 0.14 mg of PLRV/kg of potato. Modifications of an existing purification procedure are reported. Five low dosage (38-118 μg of PLRV) intravenous injections were used to produce a PLRV antiserum for use in enzyme-linked immunosorbent assays (ELISA) from tubers. PLRV was readily detected in ELISA testing of potato tubers and leaves and inPhysalis floridana Rybd. Non-specific reactions were low with all tissues. In parallel tests, a Canadian antiserum produced higher nonspecific reactions with tuber and leaf tissue. The results indicated that the use of low dosage-intravenous injections might be necessary methodology for producing PLRV antiserum for use in ELISA diagnostic tests with tuber tissue where high non-specific reactions have been reported.     

Preparation process and antimicrobial properties of cross-linking chitosan onto periodate-oxidized bamboo pulp fabric

Chitosan cross-linked bamboo pulp fabric (CCBPF) was prepared by treating the oxidized bamboo pulp fabric with the chitosan aqueous acetic acid solution. FTIR spectroscopy was used to examine the chemical bonding between chitosan and oxidized bamboo pulp fabrics, X-ray diffraction and thermogravimetry were used to detect the cellulose structure. The impact of the periodate oxidation and chitosan treatment on the physical properties of bamboo pulp fabrics was evaluated by determining the aldehyde content, weight loss, mechanical strength, wrinkle recovery angle, and moisture regain of fabrics as well as chitosan content in the composite chitosan-bamboo pulp fabrics. Antibacterial activity of the CCBPF against Staphylococcus aureus and Escherichia coli was investigated in vitro experiments. The results indicated that the aldehyde groups in the periodate oxidized bamboo pulp cellulose were reacted with the amino groups of chitosan to form Schiff base, and the resultant CCBPF displayed good wrinkle recovery angle and moisture regain. In comparison with those of the oxidized bamboo pulp fabric, the CCBPF exhibited a lower thermal stability, the crystallinity decreased from 42.73 % to 39.15 %, the mechanical strength of CCBPF had no significant change, and the CCBPF showed excellent antibacterial activity against both types of bacteria which was durable till 50 washes.     

Pre and early post-emergence weed control with Paraquat in potatoes

Studies using Paraquat herbicide for early post-emergence control of broadleaved and grass weeds in Katahdin and Russet Burbank potatoes were conducted in Maine during four growing seasons. All rates and times of application of Paraquat gave good commercial control of grass and broadleaf weeds when compared to Premerge and Dowpon treatment as checks. Paraquat applied to Katahdins 2 weeks after ground crack reduced the yield of tubers but did not significantly affect specific gravity. Yield and specific gravity of Russet Burbank was reduced by Paraquat applied one and 2 weeks after ground crack. Paraquat can be used effectively for weed control in Katahdin up to one week after ground crack without crop damage. In Russet Burbank it appeared that application at ground crack was about as late as Paraquat could be applied without affecting yield or specific gravity of tubers.     

Heritability of Yield Components Under Irrigated and Drought Conditions in Andigenum Potatoes

Drought is one of the major abiotic factors that affect potato production in the tropics and sub-tropics. Molecular plant breeding offers promising opportunities for developing drought tolerant cultivars, but genetic gains to be achieved through breeding depends strongly on the genetic variance and heritability of traits used in the selection process. In the present study, genetic variance and heritability of tuber yield and its components were estimated in the native potato cultivar group Andigenum, expected to include promising drought tolerant progenitors. Twenty-seven full sib families obtained from crossing 18 parents arranged in 3 mating sets were grown under irrigated and terminal drought conditions. Heritability for tuber yield, estimated from female to male variance components was 0.68 and 0.41, respectively, in the irrigated treatment, and only 0.18 and 0.06 under drought conditions. Tuber number was highly significantly correlated to tuber yield but the heritability of this trait (estimated both from female to male variance) was lower than yield heritability and its non-additive genetic variance was higher than its additive genetic variance, particularly when estimated from the female variance component. Heritability of average weight per tuber estimated for male variance component was very high under both irrigated and drought conditions. Its additive genetic variance was much higher than its non-additive genetic variance. However, average weight per tuber correlated to tuber yield within parents but not within families. These results indicate that selection for increased tuber yield under drought conditions in the Andigenum cultivar group may be slow due to its low heritability and high value of non-additive genetic variance. They also suggest that yield components may not be useful as indirect selection criterion for yield, because of their low heritability and/or poor association with yield. The identification of drought tolerance related traits with high heritability and closely associated to tuber yield under drought is consequently required to improve adaptation of potato to drought-prone conditions and efficient utilization of Andigenum potatoes for this purpose.     

Purification of potato virus A and its detection in potato by enzyme-linked immunosorbent assay (ELISA)

Potato virus A (PVA) was purified fromNicandra physaloides by a simple method that omitted organic solvent clarification and consisted of differential centrifugation followed by equilibrium centrifugation in CsCl. An antiserum was produced that specifically detected PVA in potato leaf sap using either the SDS-agar test or enzyme-linked immunosorbent assay (ELISA). No heterlogous reaction of the antiserum with potato virus Y was detected. Purified PVA was highly infectious; it had an A 258/280 nm absorbance ratio of 1.28. The particles had a normal intact appearance in the electron microscope. Detection of PVA in potato sprouts and foliage by ELISA was compared with the local lesion assay onPhysalis angulata L. plants. ELISA was superior over an indicator plant test when sprout tissue was used. PVA antiserum reacted similarly with mild and crinkle isolates.     

A rapid and simple method for determination of potato chloroplast DNA type

A procedure for restriction enzyme analysis of the potato chloroplast DNA (ctDNA) is described. The advantages of this method are: 1) rapid determination of ctDNA type, 2) no ultracentrifugation, and 3) low cost of analyses. This method makes it easy to distinguish the ctDNA types of wild and cultivated potato accessions.     

Detection of potato viruses X and S in tissue culture plantlets

The latex agglutination test (LAT) and enzyme-linked immunosorbent assay (ELISA) were evaluated in separate studies for their ability to detect potato virus X (PVX) and potato virus S (PVS) in tissue culture plantlets. Healthy and infected clonal lines of several potato cultivars were used. LAT was unsatisfactory because only low levels of agglutination were obtained with infected samples, and because variable and inconsistent results were obtained with both healthy and infected clones. ELISA, however, consistently gave high spectrophotometric readings and intense visual reactions for infected but not for healthy clones. The results indicate that ELISA can be used to detect PVX and PVS in tissue culture plantlets, and in programs where tissue culture is employed, early detection and elimination of infected plantlets is possible.     

The structural development and the thermal behaviours in the heat treated poly(p-phenylene terephthalamide) fibers

Poly(p-phenylene terephthalamide) fibers prepared by dry-jet wet spinning processes have a notable response to very brief heat treatment (seconds) under tension. The modulus of the as-spun fiber can be greatly affected by the heat treatment conditions (temperature, tension and duration). The crystallite orientation and the fiber modulus will increase by this short-term heating under tension. The present research reports the heat treatment techniques, devices and its process conditions. It reports in details the structural relationships between the fiber properties which are influenced by the heat treatment process. In particular, focuses deeply on the effect of the crystal orientation changes of the fibers, on the mechanical properties and, also, investigates the thermal degradation steps & behaviours of the heat treated fibers. The heat treated PPTA fibers have a molecular orientation higher than that for the as-spun one.     

Bactericidal activity of zinc oxide particles embedded in poly(vinyl pyrrolidone) electrospun fibers

Composites of metal oxide nanoparticles incorporated into poly(vinyl pyrrolidone) electrospun fibers can be considered potential and low cost bactericidal agents. Homogeneous distribution of nanoparticles in the core of fibers and minimal aggregation induced by strong interaction with polymeric template are factors that contribute with diffusion of metal oxide nanoparticles from bulk to the fiber surface and subsequent release of nanoparticles to bacterial culture. Hybrid electrospun fibers were successfully applied against bacteria as a result of reasonable degree of interaction between zinc oxide and fibers as detected from FTIR analysis, DSC curves and SEM images.     

Kinetin,thermotherapy, and tissue culture to eliminate potato virus (PVX) in potato

PVX infected plantlets from two potato cultivars grownin vitro with 0.3, 3, 30 or 300 ppm kinetin were exposed to temperatures of 28 or 35 C. After 3 wk, axillary buds were isolated and grown aseptically in organogenic media, followed by PVX testing by ELISA. The serological test was also run on whole plantlets at the end of the kinetin-temperature exposure. No donor plants exposed to 28 C nor the plantlets derived from their buds gave an ELISA (-) reaction, regardless of the kinetin content of the media or that of the cultivar. At 35 C the virus was suppressed to undetectable levels in several whole plantlets. In the cultivar Alpha, 2 out of 6 resulting plantlets after isolation of buds were virus-free in the presence of 3.0 mg/1 kinetin during the treatments. From Atzimba, about 15–40% of the regenerated plants were ELISA (-), without any relationship to the cytokinin content in the media. Heat had a stronger influence on virus elimination than kinetin and the results varied with the cultivar.     

Preparation and thermal properties of polyphenylene sulfide/organic montmorillonite composites

Cetyl trimethyl ammonium bromide (CTAB) was used for the intercalation modification of nano-montmorillonite (MMT). The spectra of Fourier transform infrared spectrometer (FTIR) and X-ray diffraction (XRD) suggested that CTAB had intercalated into the layers of MMT. And the interlayer spacing of MMT increased from 1.198 to 3.616 nm. The thermogravimetric analysis (TGA) curves of organic montmorillonite (OMMT) showed three-step degradation. The scanning electron microscope (SEM) photographs showed that surface morphology of MMT remained unchanged. Then polyphenylene sulfide (PPS)/organic montmorillonite (OMMT) composites were prepared by melt blending. And composites were treated at 180 °C for 24 h. The results of SEM showed that OMMT had good dispersion behavior and adhesion with PPS. The results of differential scanning calorimetry (DSC) showed the addition of OMMT resulted in heterogeneous nucleation crystallization of PPS. The results of TGA showed there was a good improvement of the thermal stability of PPS. The FTIR and color measurement analysis showed the addition of OMMT could improve the thermal oxidation stability.