Antimicrobial fibers based on chitosan and polyvinyl-alcohol

A series of antimicrobial fibers with different weight ratio of chitosan (CS) and polyvinyl alcohol (PVA) were fabricated via a primarily industrialized trail of wet-spinning method, and the morphology and structure of the resulting fibers were studied with the aid of scanning electron micrography (SEM), infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The CP60 blend fiber (60 % chitosan content) was confirmed as the best optimal sample among the blend fibers owing to strong intermolecular hydrogen bonds between PVA and chitosan and showed the maximum mechanical, antistatic, moisture absorption/desorption properties. The CP60 also exhibited good antimicrobial effects against Escherichia coli and Staphylococcus aureus as the chitosan fiber and could be recommended as the alternative material for the wound dressing and the food packing.     

Antimicrobial and cellular activity of poly(L-lactide)/chitosan/Imipenem antibiotic composite nanofibers

Synthesis of biocompatible polymer nanofibers is valuable, due to their use as a cover for burns and as a replacement for bandage because of their antimicrobial properties. In this study, electrospinning of chitosan(Ch) and nanofibers synthesis with antibacterial properties was investigated. Nanofibers with antibacterial properties were synthesized by electrospun of Ch/poly(L-lactide)(PLA)/Imipenem(Imi) polymer solution. The results showed that the optimized ratio of Ch/PLA polymer solution was ratio of 50:50 and Ch 2 wt% and PLA 10 wt% polymer solution was the best weight percentage for nanofiber preparation. Also, the average diameter of Ch/PLA/Imi nanofibers was 143 nm and measured with ImageJ software. Afterwards, the antibacterial properties of Imi as additives (with different percentages) was studied in the polymer solution. The scanning electron microscopy (SEM) images and antibacterial tests were showed that the electrospun of Ch/PLA/Imi polymeric nanofibers were effective against Gram negative bacteria Escherichia coli (E. coli) and inhibited growth of E. coli. The growth and viability percentage of fibroblast cells with nanofibers in αMEM culture are at desirable levels after 6 days.     

Improving certain properties of wool fibers by applying chitosan nanoparticles and atmospheric plasma treatment

The nanochitosan particles were prepared by ionic gelation method using sodium tripolyphosphate (TPP) as anionic chemical agent. Structural and morphological properties of the nanoparticles were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR) analyses. The results showed that nanoparticles were spherical with a diameter range of 17-105 nm. After nanochitosan synthesis, the effects of chitosan and nanochitosan concentrations on the dyeability, fastness properties, shrink-proofing, tensile strengths, and surface friction coefficients of untreated and plasma treated wool fabrics were investigated. The studies revealed that nanochitosan treated wool fabric possesses better dyeing and shrink-proofing properties in comparison with conventional chitosan treated fabrics.     

Durable antibacterial cotton modified by silver nanoparticles and chitosan derivative binder

This article focuses on the functional finishing of textiles using silver nanoparticles (AgNPs) and chitosan derivative binder, which was synthesized by a modification of chitosan using α-ketoglutaric acid. The binder covalently linked to cotton fabric via esterification of the hydroxyl groups on the cotton surface, and tightly adhered to surface of the AgNPs by coordination bonds. As a result, the coating of AgNPs on the cotton fabric showed excellent antibacterial property and laundering durability. After 30 consecutive laundering cycles, the Ag content on the fabrics decreased to 37.6 %, but the bacterial reduction rates against both S. aureus and E. coli were maintained over 95 %. It has potential applications in a wide variety of fields such as sportswear, socks, and medical textile.     

浅谈稻米的食味品质及其影响因素

对稻米食味品质的感官、理化分析(直链淀粉含量、胶稠度、糊化温度)及影响因素进行评价。略述食味品质是稻米品质改良的最终目标,其研发是市场经济发展的必然要求。     

Antimicrobial activity of Hedeoma drummondii against opportunistic pathogens

Hedeoma drummondii is a medicinal plant with diverse properties; however, validations of its medicinal uses are scarce. To evaluate its antimicrobial properties H. drummondii, was tested against opportunistic pathogens of medical importance. Antimicrobial tests were performed by the microdilution method in order to determine the Minimal Inhibitory Concentration (MIC) for each extract. Extracts of this plant showed relevant antimicrobial activity, results revealed that the hexanic extract has stronger activity and broader spectrum compared to acetone and methanol extracts. The activity of hexanic extract may be attributed mainly to the presence of the monoterpenes pulegone and menthol. In conclusion, the hexanic extract possess relevant antibacterial properties which suggests that H. drummondii have bioactive principles; these new data provide scientific support for the use of this plant in traditional medicine, particularly for gastrointestinal diseases.     

Comparisons of some factors affecting digestibility in sheep and cows

A comparison was made of some factors affecting digestibility in sheep and cattle. In one experiment four castrated male sheep and four non-lactating cows were given diets of hay and of hay and concentrates, and in another experiment similar groups of animals were offered diets consisting mainly of hay or hay and lucerne cobs. In both experiments there was good agreement in digestibility between the sheep and cows. With diets which did not stimulate maximum rumination, sheep tended to ruminate for a longer time per day than cows. At high feed intakes rumination times were similar in sheep and cows. Times spent eating, ruminating or chewing per unit of feed DM were 6 to 19 times longer in the sheep than in the cows. Retention times of stained hay in the gut tended to be slightly shorter in sheep than cows and those of stained barley husk and of processed lucerne were similar in the sheep and cows. The median size of faecal particles was 1.4 to 1.9 times greater in cattle than sheep. The similarities and differences between sheep and cattle in the factors affecting digestibility are discussed.     

Preparation and radiopaque properties of chitosan/BaSO4 composite fibers

Chitin and chitosan have been extensively investigated as a matrix of organic/inorganic composite. Barium, one of the radiopaque inorganic materials, can provide chitosan with radiopaque property by blending of chitosan and BaSO₄. The filtered and deaerated chitosan/BaCl₂ solutions were extruded into NaOH and Na₂SO₄ coagulation bath through a nozzle by gear pump. BaSO₄ was synthesized by the reaction between BaCl₂ and Na₂SO₄ in the coagulation bath, in which acidic chitosan solution was also solidified at the same time. In XRD, the introduction of BaSO₄ into chitosan fibers reduced the inherent peak of chitosan fibers. In angiographic observation, chitosan/BaSO₄ hybrid fibers exhibited the clear contrast images which become clear with an increase in BaSO₄ content.     

Investigations into skin strength in potatoes: factors affecting skin adhesion strength

Summary A standardised test of skin set (scuff meter) has been used to demonstrate the increase in skin adhesion of six varieties following haulm destruction. Increases in skin adhesion were characteristically linear in the six varieties but increased at different rates. At 49 days after haulm destruction, skin adhesion strengths were similar in all varieties except cv. Record which had a much greater skin adhesion strength. Differences in skin adhesion strength were poorly related to skin morphological characteristics such as skin thickness, cell size and suberin content. The method of haulm destruction affected skin adhesion strength with skins adhering more rapidly and more strongly to the tuber following haulm pulling compared with either desiccation with diquat or mechanical flailing. The method of haulm destruction did not influence skin morphological characteristics.     

Genetic and environmental factors affecting grain texture in common wheat

Thirteen wheat cultivars grown in six locations were compared for kernel weight, protein content and grain texture, as determined by the Single Kernel Characterization System (SKCS). Moreover, puroindolines a (Pin-A) and b (Pin-B) bound to starch were quantified by densitometric scanning of A-PAGE fractionations. All cultivars shared allele Pina-D1a coding for wild-type Pin-A, and differed from each other in allele composition at Pinb-D1 coding for Pin-B. Cultivars with Pinb-D1a exhibited soft grain and high amounts of Pin-A and Pin-B compared to cultivars with Pinb-D1b or Pinb-D1d. Significant genetic variation for grain hardness and Pin-A level was detected in soft cultivars. The ratio between Pin-A and Pin-B levels in soft cultivars was approximately 6:5, whereas it varied between 9:5 and 10:1 in hard cultivars. Protein content was significantly correlated with Pin-B content (r=0.34) and SKCS value (r=0.36) in soft wheats. Significant correlations (0.68 and 0.73 for soft and hard wheats, respectively) were observed between Pin-A and Pin-B levels. Grain hardness was not correlated with puroindoline levels and Pin-A/Pin-B ratio in both textural classes. By contrast, kernel weight was found to act as a major environmental factor affecting grain texture in both soft and hard wheats.     

The incidence of decay and factors affecting bacterial soft rot of potatoes

The incidence of tuber decay in rail car shipments of potatoes from the State of Washington was determined from 1965 to 1969 inclusive. Reinspection certificates revealed that 7.9% of the rail cars of potatoes shipped during this period were rejected due to tuber defects; tuber decay accounted for 63% of these rejected cars. Percentage of rejections due to tuber decay was greater for Russet Burbank than for Norgold Russet potatoes. Temperature, moisture, and oxygen levels influenced development of bacterial soft rot in freshly harvested potatoes and in potatoes stored for 3 months at 35 F (2 C) previous to treatment. When tuber surfaces were kept dry, no soft rot developed in 11 days over ranges of 50–70 F (10–21 C) and 2–20.5% oxygen levels. Freshly harvested tubers partially immersed in water did not rot when cooled to 40 F (4.4 C) in < 24 hours and held for 8 days under either 20.5 or 4% oxygen levels; however, tubers, rotted when stored similarly but at 50 F or higher temperatures. Partially immersed tubers incubated for 1 day or longer at 70 F developed soft rot in a low oxygen (4%) when later stored for, 8 days at 40 F. When rot occurred, the amount was always greater under lower oxygen levels irrespective of storage temperature. Of various cooling methods tested in rail cars loaded with 100 lb (45.4 kg) sacks of potatoes, prechilling of tubers and icing of cars prior to loading lowered floor temperatures most rapidly. Icing cars after loading lowered floor temperatures the slowest. In a carton shipment, the temperature remained above 68 F (20 C) in cartons after 8 days in transit, even though the wall and floor temperatures had cooled to near 55 F (12.8 C) by the second day. Oxygen level surrounding, tubers in the center of car loads of 100 lb sacks of potatoes was approximately 20.5% after 8 days transit.     

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.     

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.     

Some properties of soils affecting russet scab and silver scurf of potatoes

The relationship of soil ammonia, nitrates, pH, total bacteria,Streptomyces sp., temperature and moisture on the incidence of russet scab and silver scurf of potatoes was studied. The soil properties were changed by the addition of various levels of alfalfa, wheat straw and green rye residues. Within the limits of the changes caused by these residues, the most consistent relationship was found between the nitrate level in the soil and russet scab, and to a lesser extent, silver scurf. In both instances there was a general decrease in russet scab and silver scurf with increasing levels of nitrates. Also, in the only comparison made, an increasing total bacterial count in the soil resulted in a decreasing level of infection from silver scurf. In some instances the alfalfa, rye and straw residue applications caused small changes in soil pH, soil temperature, and soil moisture. These changes were not great enough to show any consistent significant relationship to russet scab or silver scurf, except for a significant negative correlation between soil moisture at the 6-inch level and silver scurf in both years.     

Genetic and environmental factors affecting pathogenicity of wheat as related to celiac disease

Gluten proteins are the basis of the rheological properties of wheat derived products, such as bread and pasta. Their particular amino acidic composition (high proline and glutamine content) is responsible for the poor gluten digestibility. Some of the high molecular weight peptides that are generated in the gastrointestinal tract are involved in an autoimmune entheropathy called celiac disease. In this work we compared the amount of peptides containing sequences involved in adaptive and immune responses, which were produced after simulated gastrointestinal digestion of prolamins extracted from different durum wheat varieties and in-bred lines. Peptides containing sequences involved in celiac disease were quantified using an isotopically labeled peptide as internal standard. The results demonstrated a very high variability in the amount of pathogenic peptides produced by different lines, showing a strong contribution of the genetic component. At the same time, the variability in total protein and gluten content was lower; the weak correlation between pathogenic peptides and the amount of gluten proteins gives rise to the possibility of a varietal selection aimed to maintain good rheological properties, but simultaneously reducing the exposure to peptides eliciting an immunological response in celiac predisposed subjects. These varieties might be useful for celiac disease prevention.