Bleaching Treatment Research Articles

Improvement of Whiteness Degree and Functional Properties of the Fermented Awachy 5 Sweet Potato Flour using Calcium Hypochlorite

Fermented Awachy 5 sweet potato flour has the potential to substitute the low protein wheat flour, but this flour has the disadvantage of having a low whiteness degree. The objective of this research was to improve the whiteness degree and the functional properties of naturally fermented of Awachy 5 sweet potato flour using calcium hypochlorite. The research was conducted by the addition of calcium hypochlorite to the fermented sweet potato chips consisted of 5 treatments; namely control (without calcium hypochlorite), 100 ppm, 150 ppm, 200 ppm, and 250 ppm. The results showed that the bleaching treatment using calcium hypochlorite increased the whiteness degree and pasting stability of fermented sweet potato flour. The optimum concentration of calcium hypochlorite was 200 ppm which produced flour with a whiteness degree of 84.60%, ash content of 0.73%, swelling volume of 7.75 mL/g, water absorption capacity of 195.80%, and pasting properties that include of peak viscosity, hold viscosity, breakdown viscosity, setback viscosity, and final viscosity about 2979 cP, 1704 cP, 1275 cP, 1345 cP, 3049 cP, respectively.

Properties Enhancement of Mengkuang Leaf Fiber/Ethylene‐Vinyl Acetate/Natural Rubber Thermoplastic Elastomer Composites by Alkaline Peroxide Bleaching Treatment

In this article, the effect of alkaline peroxide bleaching treatment using hydrogen peroxide on mengkuang leaf fiber (MLF) to the tensile, thermal properties and water absorption of thermoplastic elastomer composites based on ethylene‐vinyl acetate/natural rubber and MLF was investigated. Fiber morphology and the fiber‐matrix interface were further characterized by scanning electron microscopy (SEM). Treated composites showed better tensile properties than untreated fiber composites. SEM of the fractured surfaces of the composite specimens indicates that the bleaching treatment improved the interfacial interaction between the fiber and the matrix. The results of thermogravimetric analysis showed a higher thermal stability for treated composites than untreated composites. Furthermore, alkaline bleaching treatment has resulted in reduction of water absorption from 31% to 26% as compared with untreated composites. J. VINYL ADDIT. TECHNOL., 26:127–134, 2020. © 2019 Society of Plastics Engineers

Production of new cellulose nanocrystals from Ferula gummosa and their use in medical applications via investigation of their biodistribution

Cellulose nanocrystals (CNCs) have recently gained an increasing interest in nanomedicine. The production of CNCs from Ferula gummosa (Fg) by acid hydrolysis are a potential source for nano-medical applications. It has been affirmed by the performed Fourier transform infrared spectroscopy (FTIR) and x-ray diffraction (XRD) analysis that in the course of chemical treatment, the non-cellulosic components have been gradually eradicated, while the final achieved materials had been comprised of cellulose. A strong increase has been perceived in the crystallinity subsequent to performing the hydrolysis and bleaching treatments. In regards to thermal stability, the obtained CNCs have displayed a remarkable sign of high thermal stability. The field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) has been found that the CNCs have contained a spherical shape at the nano-scale. In the case of cell viability, the MTT (3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyl tetrazolium bromide) assay has not revealed any noticeable cytotoxic effect against the A549 cells. The CNCs have been labeled through the utilization of Tc-99m and have confirmed the stability of radiolabeled CNCs at room temperature for different times. The labeling efficiency has been observed to be more than 97%. Biodistribution profile and imaging have verified that the accumulation of 99mTc-CNCs has been higher in kidneys and had been circulating in the blood. The results indicated that it is possible to convert a low-cost byproduct such as roots plants into a valuable material such as cellulose nanocrystals, which are known as promising candidates to be applied for bioimaging and diagnostic.

Dental Whitening Gels: Strengths and Weaknesses of an Increasingly Used Method

Many people nowadays undergo treatments to improve their aesthetics, often neglecting the general state of health. Aesthetics and appearance have become of prime importance, perhaps correlating with of the advent of social networks and digital photographs. One of the most requested aesthetic treatments for dentists is dental bleaching through the use of whitening gels. Dental bleaching is a treatment which involves an improvement in the chrome of the teeth in a short time, and this treatment appears not invasive for the patients. In-office and at-home bleaching treatments can be found. The purpose of this scientific study is to evaluate all of the advantages and disadvantages of this medical treatment. In this study, were report information and items related to bleaching side effects. Dentists often find themselves in disagreement on this topic. The PICO (Population/Intervention/Comparison/Outcome) question investigated was: Are dental patients who have dental bleaching an increased risk of teeth damage? All of the data in the literature has been collected, and all of the side effects of this treatment were evaluated. 263 studies emerged from initial research; only 14 were screened after screening, as they contained sufficient data to evaluate the side effects of treatment. One certain thing emerged; among the contraindications to the treatment of dental bleaching dentinal hypersensitivity could be cited. In fact, one of the most reported undesirable effects regards this problem. Other studies have evaluated pain, color improvement and duration, or patient satisfaction. Dental bleaching is a treatment that aims to improve the aesthetics of our patients; this is also reflected from a psychological point of view and therefore has effects on general health. However, the whitening treatment is not suitable for everyone and must be carefully evaluated by a specialist. This treatment also entails maintenance by the patient and therefore better compliance to normal oral hygiene procedures.

Effects of bleaching and heat treatments on Indosasa angustata bamboo in Vietnam

Effects of bleaching and heat treatment were investigated for Indosasa angustata bamboo grown in Vietnam. Hydrogen peroxide (H2O2) at a concentration of 30% was used for the bleaching process. For the heat treatment, the bamboo strips were heat-treated at two different temperatures (120 °C and 140 °C) for 3 h. There was a slight increase in the lignin and hemicellulose contents of the samples treated at 100 °C for 1 h when H2O2 was used. The water absorption rate did not change much, and the treated bamboo strips became brighter after undergoing bleaching. For the heat-treated samples, the lignin content slightly increased after the samples were heated at both 120 °C and 140 °C for 3 h. Moreover, the higher heating temperature led to a lower hemicellulose content, a darker colored bamboo sample, and a lower water absorption rate for the treated bamboo strips.

Bleaching and cold stratification can break dormancy and improve seed germination in Cyperaceae

Seed germination of sedges is often difficult, due to physiological dormancy and the hard seed coat. It has been proposed that chemical scarification by sodium hypochlorite (‘bleach’) and cold stratification might successfully break this type of dormancy and improve seed germination rates. Yet the choice of the dormancy-breaking conditions in previous studies appears to be arbitrary, resulting in inconsistent results when applied to the seeds of other sedges.Here, we propose and test a strategy for optimizing the dormancy-breaking treatment to achieve higher germination rates and minimize the number of damaged seeds in 16 ‘hard-to-germinate’ members of the Cyperaceae family. The seeds were soaked in 0–10% bleach solutions for different periods of time (from 1 to 120 h) followed by immediate germination tests or cold stratification for either 9 or 18 weeks.To break dormancy, we recommend pretreatment of seeds with sodium hypochlorite, possibly followed by cold stratification, but details (bleach concentration-duration and stratification duration follow each species) varied by species: Bolboschoenus glaucus, Eleocharis palustris and E. uniglumis (2–6% for 6–48 h, 9 weeks), Cladium mariscus (4–10% for 72–120 h, 18 weeks), Schoenoplectiella mucronata (2–10% for 72–120 h, 0 weeks), Schoenoplectus tabernomontani (6–10% for 24–48 h, 18 weeks), Schoenus nigricans (4–6% for 24–72 h, 0 weeks), Bleach-scarification treatment negatively affected seed germination in Eleocharis ovata, Eriophorum latifolium, Rhynchospora alba, Schoenoplectiella supina and Scirpoides holoschoenus, whereas seeds of Bolboschoenus maritimus and Rhynchospora glomerata showed no response to the treatment.We conclude that careful selection of seed dormancy-breaking conditions plays a crucial role in optimizing sedge seed germination. The proposed range-searching approach can help to detect the species-specific, in some cases very narrow, optimum for the bleaching treatment followed by cold stratification, at least in some species of the Cyperaceae family.

Effects of Alpha-tocopherol Antioxidant on Dentin-composite Microtensile Bond Strength after Sodium Perborate Bleaching

It has been reported that bond strength can be reversed to prebleached levels with the application of 10% alpha-tocopherol in a 2-hour time frame or by delaying bonding for 2 weeks. This study evaluated the effectiveness of a 5-minute application of 20% alpha-tocopherol to reverse the deleterious effects of nonvital bleaching on consequent bond strength. Thirty third molars were assigned to the following 3 groups: unbleached, bleached, and bleached followed by treatment with alpha-tocopherol. The bleached groups were exposed to sodium perborate (2 g/mL) for 7 days. The postbleach treatment group was subsequently treated with 20% alpha-tocopherol for 5 minutes, and then all groups were restored with composite resin. After 24 hours of storage at 37°C and 100% humidity, restored tooth specimens were sectioned into 1-mm2 dentin-composite beams. Six beams from each tooth were subjected to microtensile bond strength testing. Representative beams were further evaluated with Raman microspectroscopy and scanning electron microscopy. The mean bond strength values (MPa) for each group were as follows: unbleached control group = 26.2, bleached control group = 20.3, and post–bleach treatment group = 18.5. A 1-factor analysis of variance and Tukey post hoc test (α = 0.05) indicated that bleaching had a detrimental effect on bond strength and that short-term alpha-tocopherol treatments did not improve postbleach bond strength. Raman microspectroscopy and scanning electron microscopy revealed no noted improvement for the post–bleach treatment group.The application of 20% alpha-tocopherol in a clinically relevant time frame was not effective in counteracting the deleterious effect of bleaching on bond strength. Bonding procedures should be delayed after tooth bleaching.

Investigations Into the Reproductive Biology of the Southern Appalachian Endemic Piratebush (Buckleya distichophylla): Pollination Biology, Fruit Development, and Seed Germination

Endemic to the mountains of Tennessee, North Carolina and Virginia, piratebush (Buckleya distichophylla, Santalaceae) is a rare, dioecious, hemi-parasitic shrub with a scattered and isolated distribution. Vegetative reproduction and few visible seedlings within the densest population of piratebush on Poor Mountain in southwest Virginia emphasize the need for research into this species' reproductive biology to inform conservation strategies. Pollination data showed no evidence for wind pollination; instead multiple diurnal floral visitors to staminate flowers were observed. Fluorescence microscopy of stigma and styles on initiated fruits revealed almost 95% with pollen deposition. Most initiated fruits (52%) had tube growth continue to the base of the style, indicating potential fertilization. Pollination experiments showed outcrossing was necessary for fruit set. Non-pollinated flowers in bags had 0% fruit development, whereas fruit development in both open pollinated (86%) (p< 0.0001) and hand pollinated (65%) treatments (p<0.0001) were significantly greater. Embryo viability analysis indicated 73% of seeds had healthy embryos. Germination trials indicated that seeds must undergo stratification for successful germination. Germination for control (70.9%) and 10 min bleach (72.6%) treatments were significantly higher than mechanically scarified fruits/seeds (27.2%), suggesting a potentially negative impact that rodent gnawing would have on seed germination. Further, evidence of heavy seed predation was observed. These results suggest that there may be sufficient pollinators, successful outcrossing and seed development, and that embryos are viable and have the potential to germinate, but imply that seed predation may be a key reproductive constraint for piratebush.

Kinetic analysis of cellulose extraction from banana pseudo-stem by liquefaction in polyhydric alcohols

The objective of this work is to track the composition changes in the process of liquefaction of banana pseudo-stem (BPs) and to maximize the cellulose fraction in the liquefied residue. Typical kinetics parameters of raw BPs and its three major components (lignin, hemicellulose and cellulose) were determined using kinetic models and transition-state theory. The results showed that cellulose had the highest activation energy and lowest reaction rate. The liquefied polyols were separated by water and acetone, and the functional groups, molecular weight distribution, acid values and hydroxyl values of different soluble parts were analyzed, providing an overall insight into the liquefaction behavior of BPs. The most suitable liquefaction conditions to avoid polycondensation and maximize cellulose content in the residues was at 150 °C with a reaction time of 90 min. Cellulose-enriched residues were readily purified by subsequent bleaching treatments. Based on the results of SEM, XRD, FTIR, TG and wet chemistry analyses, a mechanism of cellulose micro-fibril extraction from solid liquefied residues was proposed.

Clinical analysis of color change and tooth sensitivity to violet LED during bleaching treatment: A case series with split-mouth design.

The aim of this study was to analyze bleaching treatment performed with different products, with or without the use of Violet LED. The color and dental sensitivity of six patients were evaluated as follows: (1)at-home bleaching with 10% Carbamide Peroxide (CP); (2)in-office bleaching with 17.5% Hydrogen Peroxide (HP), and (3)treatment with a placebo gel. All patients, including patients receiving at-home bleaching, received irradiation with violet LED in the office. The right hemiarch was protect with silicone. The color was evaluated using Vita Easyshade digital spectrophotometer and the Vita scale on teeth 13-23. Visual analog scale sensitivity analysis was performed per hemiarch, while the thermal sensation threshold was performed on teeth 11, 13, 21 and 23. Regarding the color change (ΔE) it can be observed that treatment 1, in which 10%CP was used, presented the highest values, followed by treatment 2, in which 17.5%HP was used. Regarding sensitivity, only patients who received 17.5%HP showed moderate sensitivity, and there was no difference between the arches. The analysis of dental thermal sensation threshold showed that there was more dental sensitization between 7 and 14 days and that the use of violet LED made the teeth more sensitive. It was concluded that violet LED enhanced the bleaching effect when used with 10%PC gels, and a discreet effect was seen when used either in conjunction with 17.5%PH or alone. Violet LED had no effect on pain sensation, but increased the detection threshold of thermal changes in the teeth that were irradiated.

Microwave-assisted formic acid extraction for high-purity cellulose production

The effective separation of hemicelluloses and cellulose is the prerequisite for creating high-value products using wood wastes. In this study, a novel process including mechanical pre-beating, microwave-assisted formic acid (MAFA) extraction, and bleaching treatment was developed for producing high-purity cellulose from the pulp fibers of hardwood waste. Most hemicelluloses and lignin were simultaneously removed (i.e., hemicelluloses were separated from cellulose) due to the MAFA treatment. The pulp fibers were pre-beaten for a loose fiber structure for the formic acid impregnation. The results showed that the introduction of microwave could significantly enhance hemicellulose removal and separation from pulp fibers. The MAFA treatment was performed under atmospheric pressure and mild condition (≤ 100 °C), which led to the significant increase in the lignin yield, cellulose content, crystallinity index, and crystallite homogeneity. After the beating pretreatment and MAFA process (88% formic acid, 100 °C, 4 + 4 h), the hemicellulose removal rate reached 75.5%, and the cellulose purity was as high as 93.2% along with a maximal cellulose crystallinity index (77.5%) and minimum crystallite cross-sectional area (12.40 nm2).

Cellulose nanocrystals derived from Enteromorpha prolifera and their use in developing bionanocomposite films with water-soluble polysaccharides extracted from E. prolifera

The biomass from Enteromorpha prolifera is used to exploit and transfer this common green bloom algae into new value-added products. In this work, cellulose nanocrystals (CNCs) were first prepared with the cellulose extracted from the biomass of E. prolifera. Initially, cellulose was treated by alkali and bleaching treatments. Subsequently, CNCs were isolated by acid hydrolysis with different concentrations. Structural changes and crystallinity were characterized by Fourier transform infrared spectroscopy (FTIR) spectroscopy, X-ray diffraction (XRD) analysis and t thermogravimetric analysis. The crystallinity index and crystallite size of the prepared CNCs depended mainly on acid concentrations. TEM observation revealed that the CNCs obtained by hydrolysis with 60% acid (CNC60) exhibited a ‘needle-like’ nanocrystals with a length of 177 ± 12 nm and width of 3 ± 1 nm, indicating that the CNC60 had a high ratio aspect and could serve as reinforcement nanofiller. Further investigation showcased that the addition of CNC60 exhibited the best effect for enhancing the mechanical properties of bionanocomposite films derived from the water-soluble polysaccharides extracted from the biomass of E. prolifera. Therefore, a new strategy was offered in this study for the comprehensive utilization of E. prolifera biomass to fabricate them into high-strength film materials.

Fabrication and tensile properties of bamboo micro-fibrils (BMF)/poly-lactic acid (PLA) green composite

In this research has been focused on the fabrication of green composites (GC) from emultion-type poly-lactic acid (PLA) biodegradable resin with bamboo micro-fibrils (BMF) reinforcement. BMF were extracted by combination methods: chemical solution and mechanical treatment. The chemical solution: alkalization of 5% (weight/volume) sodium hydroxide (NaOH) for 72 hours and bleaching of 2,8% volume natrium hypoclorit (NaClO) for 12 hours. And for mechanical treatment: high speed-blender for up to 30 minute along with the alkalization process. The chemical structure of the resulting cellulose BMF was studied by Fourier Transform Infra-Red (FTIR) spectroscopy. The alkalization and bleaching treatment were affected by the BMF cellulose content. Fabrication of green composites with BFC loading from 0%, 20%, 30%, 40% and 50% of mass were prepared using hot-press molding at constant temperature of 170°C, pressure of 10 MPa and time molding of 10 minutes. Tensile strength and elastic modulus was investigated using computerized Universal Testing Mechines HT-2402 with crosshead speed of 5.0 mm/min. The measurement finding showed that the tensile strength and elastic modulus were affected by the BMF content. The results obtained emphasize the application of bamboo micro-fibrils composites (BMC), as a potential materials in biodegradable based or green composites (GC).

Fabrication of pandanus tectorius (screw-pine) natural fiber using vacuum resin infusion for polymer composite application

Natural cellulose fiber extract from Pandanus tectorius (Screw pine) leaves is comprehensively investigated as viable alternative for synthetic based fibers made from petro-chemical which is non-degradable and toxic. P. tectorius leaves fiber is extracted and investigated as reinforcement in polymer composite for engineering applications. The habitant are easily found and grown along mangroves and in local jungles located at shallow water. The plant can grow up to 14m tall. In order to use these continuous cellulose fibers as reinforcement in polymer composites, the microstructural analysis and yield content analysis were carried out using SEM micrographs to establish the certainty of using them as reinforcement fiber. The alkaline, bleaching and combined alkaline-bleach treatments are utilized in extraction of the cellulose fiber to evaluate the effect on the mechanical property. The cellulose percentage of the fiber was increased as the concentration and soaking time were increased. The extraction process resulted in 73% cellulose percentage for 10wt. % NaOH and 120min treatment. Hence, it caused 87% increment in cellulose percentage compared to the untreated leaf. The combined alkali-bleach cellulose fiber composite showed 40% higher tensile strength compared to untreated cellulose fiber composite at 35 2.8MPa.

Effect of H2O2 Bleaching Treatment on the Properties of Finished Transparent Wood.

Transparent wood samples were fabricated from an environmentally-friendly hydrogen peroxide (H2O2) bleached basswood (Tilia) template using polymer impregnation. The wood samples were bleached separately for 30, 60, 90, 120 and 150 min to evaluate the effects on the changes of the chemical composition and properties of finished transparent wood. Experimental results showed decreases in cellulose, hemicellulose, and lignin content with an increasing bleaching time and while decreasing each component to a unique extent. Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM) analysis indicated that the wood cell micro-structures were maintained during H2O2 bleaching treatment. This allowed for successful impregnation of polymer into the bleached wood template and strong transparent wood products. The transparent wood possessed a maximum optical transmittance up to 44% at 800 nm with 150 min bleaching time. Moreover, the transparent wood displayed a maximum tensile strength up to 165.1 ± 1.5 MPa with 90 min bleaching time. The elastic modulus (Er) and hardness (H) of the transparent wood samples were lowered along with the increase of H2O2 bleaching treatment time. In addition, the transparent wood with 30 min bleaching time exhibited the highest Er and H values of 20.4 GPa and 0.45 GPa, respectively. This findings may provide one way to choose optimum degrees of H2O2 bleaching treatment for transparent wood fabrication, to fit the physicochemical properties of finished transparent wood.

Influence of Staining Solutions on Color Change and Enamel Surface Properties During At-home and In-office Dental Bleaching: An In Situ Study.

The purpose of this in situ study was to evaluate the influence of staining solutions (coffee and cola) on the color change, microhardness, roughness, and micromorphology of the enamel surface during at-home and in-office dental bleaching. One hundred and thirty-five enamel bovine blocks were prepared to perform the evaluations. Fifteen volunteers used an intraoral appliance with nine enamel blocks for 15 days. The enamel blocks were randomly assigned among the different groups according to the three treatments: in-office bleaching with high hydrogen peroxide concentration (Opalescence Boost PF 40%, Ultradent) for 40 minutes in three sessions (first, eighth, and 15th days of treatment), at-home bleaching with low carbamide peroxide concentration (Opalescence PF 10%, Ultradent) for 60 minutes daily for 15 days, and a control group (no bleaching agent applied). The enamel blocks were immersed daily in different staining solutions (coffee or cola) for 30 minutes for 15 days or were not submitted to staining (control) to obtain a factorial scheme (3×3) of the dental bleaching treatment and staining solution (n=15). The microhardness analyses (Knoop), roughness evaluations (Ra), surface micromorphological observations, and color measurements (using the CIELAB system and the VITA Classical scale) were made before and after the bleaching treatments to assess immersion in staining solutions. Mixed model tests showed that there was a decrease in enamel microhardness after exposure to cola compared with coffee and the control group (p<0.0001) for both bleaching techniques. Roughness was higher for the cola groups (p<0.0001), and there was no significant difference between the coffee and the control groups. Generalized linear models showed that when no staining solution was applied, lighter color scores were found for the VITA Classical scale (p<0.0001). Without the staining solutions, there was an increase in luminosity (ΔL) (p=0.0444) for in-office bleaching. Lower values of Δa (p=0.0010) were observed when the staining solutions were not used. The Δb (p=0.3929) did not vary significantly between the bleaching agents, but when cola was applied, the values were significantly higher than for the control (p=0.0293). Higher values of ΔE (p=0.0089) were observed for in-office bleaching without staining solutions, while lower values of ΔE were observed for the in-office associated with coffee immersion. Regardless of whether being submitted to bleaching, the enamel stained with cola showed a decrease in microhardness, an increase in roughness, and changes in the micromorphology. The efficacy of the bleaching agents was greater when no staining solution (cola or coffee) was used, and in-office bleaching showed greater color change than the at-home bleaching technique.

A New Approach for Dental Bleaching Using Violet Light With or Without the Use of Whitening Gel: Study of Bleaching Effectiveness.

The objective of this study was to evaluate the effectiveness of violet light-emitting diodes (LEDs) in dental bleaching treatment when used in conjunction with bleaching gels containing different concentrations of hydrogen peroxide (HP). Here, 90 bovine teeth (n=15) were randomly assigned to the following groups: GI, placebo without light; GII, 35% HP without light; GIII, 17.5% HP without light; GIV, placebo with violet LED; GV, 35% HP with violet LED; and GVI, 17.5% HP with violet LEDs. Three bleaching sessions of 45 minutes were conducted; 21 cycles involving one minute of irradiation by violet LEDs with 30-second intervals were performed during each session of bleaching (GIV, GV, and GVI). Color changes (ΔE, ΔL, Δa, and Δb) were analyzed using a visible ultraviolet light spectrophotometer 7 days after each bleaching session. The mean ΔE, ΔL, Δa, and Δb values were compared between groups by analysis of variance and Tukey tests, with a significance level of 5%. The groups treated with 35% HP had higher ΔE and ΔL and lower Δb values, regardless of whether violet light was used. The group that received only violet LED differed from the control group in terms of ΔE, and the group treated with 17.5% HP and violet LED presented higher ΔE values than the group treated with 17.5% HP only. Thus, violet light did not influence bleaching efficacy when using 35% HP, but when used in conjunction with 17.5% HP, it increased the bleaching efficacy. Moreover, use of the violet LED only also prompted a bleaching effect, although it was less marked.

Preparation and Characterization of a Biocomposite Based on Cork Microparticles in Poly(β-hydroxybutyrate)-co-Poly(β-hydroxyvalerate) Matrix

Abstract Poly(β-hydroxybutyrate)-co-poly(β-hydroxyvalerate) (PHBV) loaded with 1 to 10 wt.% of cork microparticles (CM) were manufactured via compression molding technique. CM were isolated by alkali, bleaching and acid hydrolysis treatments. They were then added to the PHBV matrices via solution casting technique. The filler microparticles showed typical diameters of 10 to 55 μm. Mechanical tests in tension showed that in PHBV containing 5 wt.% CM the Young's modulus and the tensile strength increased by 50% and 10% respectively. Meanwhile, the elongation at break decreased by 70% for the same CM content. The mechanical behavior of the reinforced composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy. The temperature of initial degradation Tid, the temperature at 5% weight loss Td5% and the temperature of maximum degradation Tdmax increase with increasing CM content by up to 13.6°C, 10.1°C and 12.3°C respectively for the composite of 5 wt.%. The composite with 10 wt.% CM content showed the best thermal stability with temperature increments of 20°C, 14.1°C and 21.5°C respectively. DSC results showed that the presence of CM has a very weak influence on the melting/crystallization behavior of the composites.

Bacterial Stabilization of a Panel of Picornaviruses.

Several viruses encounter various bacterial species within the host and in the environment. Despite these close encounters, the effects of bacteria on picornaviruses are not completely understood. Previous work determined that poliovirus (PV), an enteric virus, has enhanced virion stability when exposed to bacteria or bacterial surface polysaccharides such as lipopolysaccharide. Virion stabilization by bacteria may be important for interhost transmission, since a mutant PV with reduced bacterial binding had a fecal-oral transmission defect in mice. Therefore, we investigated whether bacteria broadly enhance stability of picornaviruses from three different genera: Enterovirus (PV and coxsackievirus B3 [CVB3]), Kobuvirus (Aichi virus), and Cardiovirus (mengovirus). Furthermore, to delineate strain-specific effects, we examined two strains of CVB3 and a PV mutant with enhanced thermal stability. We determined that specific bacterial strains enhance thermal stability of PV and CVB3, while mengovirus and Aichi virus are stable at high temperatures in the absence of bacteria. Additionally, we determined that bacteria or lipopolysaccharide can stabilize PV, CVB3, Aichi virus, and mengovirus during exposure to bleach. These effects are likely mediated through direct interactions with bacteria, since viruses bound to bacteria in a pulldown assay. Overall, this work reveals shared and distinct effects of bacteria on a panel of picornaviruses.IMPORTANCE Recent studies have shown that bacteria promote infection and stabilization of poliovirus particles, but the breadth of these effects on other members of the Picornaviridae family is unknown. Here, we compared the effects of bacteria on four distinct members of the Picornaviridae family. We found that bacteria reduced inactivation of all of the viruses during bleach treatment, but not all viral strains were stabilized by bacteria during heat treatment. Overall, our data provide insight into how bacteria play differential roles in picornavirus stability.

The effect of alkalization and bleaching treatment of Sorghum fibre on the crystallinity index of PP composite

Natural fibres are increasingly being employed as the reinforcing material for polypropylene (PP). However, the fibre surface needs to be modified with particular treatment to improve the interfacial adhesion and thus mechanical properties of the composite. The aim of this work was to study the effect of alkalization and bleaching treatment to the structure of sorghum fibre and how it affects the crystallinity of polypropylene (PP)-sorghum composite. For the alkalization treatment, the fibre was soaked in NaOH solution 10% v/v while for the bleaching treatment NaClO2 solution 1.7% v/v was used. The FTIR and SEM analysis of the sorghum fibres indicated that the alkalization and bleaching process eroded some part of amorphous structure in the fibre. It was found that using the treated fibre as the reinforcing agent in PP matrix could increase the crystallinity of the resulting composite compared to the crystallinity of pure PP.