The effect of accelerated aging on the color stability and translucency of novel zirconia reinforced rice husk dental composite resin in different infusion media / O efeito do envelhecimento acelerado na estabilidade de cor e translucidez de uma nova resina composta de casca de arroz reforçada com zircônia em diferentes meios de infusão

Objective: To compare the color stability and translucency of aged and unaged experimental zirconia reinforced rice husk nanohybrid composite resin (Zr-Hybrid) with a commercialized nanofilled and a microhybrid composite resin after immersion in four different infusion media. Material and Methods: Three groups of standardized disc-shaped composite resin with 80 samples per group were prepared as follow: Group 1 (Filtek-Z350-XT), Group 2 (Zmack-Comp), and Group 3 (Zr-Hybrid). Each group was further subdivided into aged (n=40) and unaged (n=40) groups. Initial color measurements were taken using a digital spectrophotometer based on CIE L*a*b* color system. Samples in aged subgroup were subjected to 2500 thermal cycles. Subsequently, all samples were immersed in four different types of infusion media (n=10): T1 - Distilled water, T2 - Soft drink, T3 - Tea and T4 - Coffee. After 15 days, color measurements of all samples were measured again. Data were analyzed using two-way ANOVA followed by Bonferroni and paired sample t-tests with a significance level set at P=0.05. Results: Unaged Zr-Hybrid showed comparable color change to Zmack-Comp and Filtek-Z350-XT (P=0.181), but aged Zr-Hybrid demonstrated the lowest color change (P<0.001). Zr-Hybrid exhibited the lowest translucency value (P<0.001), but no significant color and translucency changes (P=0.051 and P=0.069, respectively) were observed between unaged and aged Zr-Hybrid. Soft drink had the greatest effect (P<0.001) on color change, while coffee showed the greatest effect (P<0.001) on translucency. Conclusion: Although Zr-Hybrid showed greater opacity, it still retained its color stability and translucency after accelerated aging compared to commercialized microhybrid and nanofilled composite resins. All infusion media caused discoloration and affected the composite resins' translucency. (AU)

Objetivo: Comparar a estabilidade de cor e translucidez de uma resina composta nanohíbrida de casca de arroz reforçada com zircônia experimental envelhecida e não envelhecida (Zr-Hybrid) com uma resina composta comercial nanoparticulada e microhíbrida após a imersão em quatro meios de infusão diferentes. Material e Métodos: Três grupos de resina composta em forma de disco padronizado com 80 amostras por grupo foram preparados da seguinte forma: Grupo 1 (Filtek-Z350-XT), Grupo 2 (Zmack-Comp) e Grupo 3 (Zr-Hybrid). Cada grupo foi subdividido em grupos de envelhecimento (n = 40) e não envelhecimento (n = 40). As medições iniciais de cor foram feitas usando um espectrofotômetro digital baseado no sistema de cores CIE L * a * b *. As amostras do subgrupo envelhecido foram submetidas a 2500 ciclos térmicos. Posteriormente, todas as amostras foram imersas em quatro tipos diferentes de meios de infusão (n = 10): T1 - Água destilada, T2 - Refrigerante,T3 - Chá e T4 - Café. Após 15 dias, as medições de cor de todas as amostras foram medidas novamente. Os dados foram analisados usando ANOVA dois fatores seguido por Bonferroni e testes t pareados com nível de significância estabelecido em P = 0,05. Resultados: O grupo Zr-Hybrid não envelhecido mostrou uma mudança de cor comparável a Zmack-Comp e Filtek-Z350-XT (P = 0,181), mas o grupo Zr-Hybrid envelhecido demonstrou a menor mudança de cor (P <0,001). Zr-Hybrid exibiu o menor valor de translucidez (P <0,001), mas nenhuma mudança significativa de cor e translucidez (P = 0,051 e P = 0,069, respectivamente) foram observadas entre Zr-Hybrid não envelhecido e envelhecido. O refrigerante teve o maior efeito (P <0,001) na mudança de cor, enquanto o café apresentou o maior efeito (P <0,001) na translucidez. Conclusão: Apesar do grupo Zr-Hybrid tenha mostrado maior opacidade, ele ainda manteve sua estabilidade de cor e translucidez após envelhecimento acelerado em comparação com resinas compostas micro-híbridas e nanoparticuladas comercializadas. Todos os meios de infusão causaram descoloração e afetaram a translucidez das resinas compostas (AU)

Defluoridation Potential of Rice Husk, Groundnut Shell as a Conventional Alternative for Fluoride Removal – A Review

Fluoride occurs naturally in our environment but we consume it in small amounts. Exposure can occur through dietary intake, respiration and fluoride supplements. The most important factor for fluoride presence in alimentation is fluoridated water. Fluoride content in groundwater has become a national issue affecting the entire India. When the recommended limit of fluoride by WHO is 1.5 mg/L, in some particular parts of India fluoride levels are as high as 35 mg/l. Increased fluoride intake causes dental fluorosis, skeletal fluorosis and neurological problems. Major problems associated with fluoride remediation are lack of cheap adsorbent to remove fluoride content in water for poor communities of India. Hence, development of community-based defluoridation unit is needed with a technique which is cost-effective, technologically simple in operation while being able to keep the fluoride level in permissible limits. On the basis of extensive investigations, different researchers have developed simple and economical domestic defluoridation processes The present review gives a brief account of prevalence, sources of fluoride toxicity and cost effective defluoridation method carried out on effects of fluoride in the last few decades. Thus cost effective absorbent which has high efficacy in fluoride removal from water can be provided to poor communities thereby preventing fluorosis

Adsorption Properties of Thermally Treated Rice Husk for Removal of Sulfamethazine Antibiotic from Pharmaceutical Wastewater

Equilibrium sorption of the Thermally Treated Rice Husk (TTRH) for Sulfamethazine (SMT) adsorption was studied. The Physico-chemical properties of the modified rice husk were determined. The equilibrium sorption data were fitted into Langmuir, Freundlich and Dubinin–Radushkevich isotherms. Of the three adsorption isotherm, the R2value of Langmuir isotherm model was the highest. Also compared to other isotherms the AARE coefficient for the Langmuir isotherm is low,which indicates favorable sorption. The maximum monolayer coverage (qm) from Langmuir isotherm model was determined to be 19.11 mg/g, the separation factor indicating a favorable sorption experiment is 0.446. Also from Freundlich Isotherm model, the sorption intensity (n) which indicates favorable sorption andthe correlation value are 1.84 and 3.79 respectively. The mean free energy was estimated from Dubinin–Radushkevich isotherm model to be 9.18 KJ/mol which clearly proved that the adsorption experiment followed a physical process

Morphological and Compositional Changes Exhibited by Rice Husk When Subjected to Synergistic Thermochemical Treatments

@#Introduction: Rice husk has portrayed great potential in becoming a sustainable biomass source in producing silica, cellulose and carbon materials, which garnered widespread interest among researchers. The objective of the current study is to determine the morphological and compositional changes in rice husk due to the synergistic effects of thermochemical treatment. Methods: Washed and dried rice husk was blended into a fine powder and then subjected to step-wise heat treatment and acid digestion to produce white ash. The intermittent products, as well as the original rice husk and the final ash product, were characterised using analytical instruments to document the morphological and chemical composition changes. Results: This report highlights the production of pure rice husk ash using a step-wise treatment using a combination of thermochemical treatment and carbonisation. The results showed that a partial breakdown of the lignocellulose components was achieved using directed thermal treatment at low temperature. The ionic impurities were leached out in subsequent heated acid treatment. Thereafter, the carbonaceous organic matter was completely converted to carbon during the carbonisation of the sample and the remaining carbon residue was removed during calcination. High purity ash contained agglomerated and nanostructured silica in the dimensions of 20 to 50 nm in the amorphous form. Conclusion: The step-wise treatment allowed systematic removal of each compound while maintaining the amorphous mineral phase of silica and avoiding carbon fixation. Understanding the effect of each treatment offers insight to produce purer silica from rice husk.

Synthesis of enriched biochar as a vehicle for phosphorus in tropical soils

Phosphorus (P) is one of the nutrients that most limits agricultural productivity, especially in tropical soils. Enriched biochar has been proposed to increase the bioavailability of P and other nutrients in the soil. Thus, the objective of this study was to evaluate the availability of P in phosphate biochar (composed of biomass and soil) as a function of the triple superphosphate mixture before and after the pyrolysis process. We produced eight types of enriched biochar via pyrolysis by combining sandy or clayey soil with rice or coffee husk, and by adding triple superphosphate before or after pyrolysis. The heating of the phosphate fertilizer during the pyrolysis process resulted in a higher crystallinity of the phosphates, lower content of labile fractions of P and lower content of available P in phosphate biochars than when the superphosphate was added after pyrolysis. (AU)

Nutrient compositions of distillers dried grain from rice husks with co-culture fermentation of Saccharomyces cerevisiae with Candida tropicalis

Aims@#Distillers dried grains are the nutrient rich co-product of dry-milled ethanol production. The present study aimed to prove that the nutritional composition of distillers dried grain from a crude hydrolysate of rice husk fermented by co-cultures of Saccharomyces cerevisiae with Candida tropicalis difference from unfermented crude rice husk hydrolysate and mono-cultured S. cerevisiae or C. tropicalis. @*Methodology and results@#The effects of mono- and co-cultures S. cerevisiae with C. tropicalis on the nutrient compositions of distillers dried grain were investigated. The crude rice husk hydrolysate in distilled water contained molasses, urea, sodium nitrate, ammonium nitrate, potassium phosphate and magnesium sulfate heptahydrate were fermented by mono- and co-cultures of S. cerevisiae with C. tropicalis for 7 days at 28-30 °C and stored with a relative humidity of 60-70% in the dark. A mono- and a co-culture fermentation of S. cerevisiae and C. tropicalis increased the crude protein, crude fat, crude fibres, ash, and calcium contents of the rice husk feedstock and decreased the metabolic energy reducing sugars. @*Conclusion, significance and impact of study@#Some nutrient components of the DDG crude rice husk hydrolysate performed higher than the non-fermentation of rice husks. The finding of this study will serve as a basic reference for future studies to utilize by-product of ethanol production from rice husks for animal feed formulation.

Multi-criteria Selection of Distributed Mini Generation Systems Using Rice Husk

ABSTRACT This paper presents a multi-criteria methodology to support decision making for management and selection of distributed mini generation sources (GD) using rice husk. Considering the potential of residual biomass, the developed model is based on the Analytic Hierarchy Process (AHP) method to evaluate the main technological arrangements of generation against the technical, economical, social-environmental aspects. Considering the possibility of energy transformation of rice husk, the following alternatives for distributed mini generation are considered: steam turbine, gas turbine, micro turbine, fuel cells, alternative combustion engine and Stirling engine. Regarding the evaluation aspects, it is defined energy efficiency, environmental impacts, social impacts, lifespan, access to technology, generation capacity, installation cost & operation and maintenance costs. Finally, the alternatives to use rice husk with these sources are classified according scenarios turned to social-environmental and economical purposes.

Co-Production of Nattokinase and Poly (γ-Glutamic Acid) Under Solid-State Fermentation Using Soybean and Rice Husk

ABSTRACTThe aim of this work was to study the co-production of nattokinase and poly (γ-glutamic acid) by Bacillus subtilis natto with soybean and rice husk under solid-state fermentation (SSF). The results showed that the size of soybean particle and rice husk significantly improved the co-production of nattokinase and poly (γ-glutamic acid), yielding 2503.4 IU/gs and 320 mg/gs, respectively in the improved culture medium composed of 16.7% soybean flour and 13.3% rice husk with 70% water content. The yields increased by approximate 7- and 2-fold factor relative to their original ones. Thus, the co-production of nattokinase and poly (γ-glutamic acid) under SSF could be considered as an efficient method to exploit agro-residues for economical production of some higher-value products.

Comparative Evaluation of the Disintegrant Properties of Rice Husk Cellulose, Corn Starch and Avicel in Metronidazole Tablet Formulation.

Cellulose is a polysaccharide that has been employed in pharmaceutical applications over the years. However, the quest for waste management and an alternative to imported raw materials for locally manufactured drug products necessitated this study. This study was undertaken to explore the application of cellulose extracted from waste, rice husk as a disintegrant in the formulation of metronidazole tablets for immediate release. Cellulose was extracted from rice husk and characterized. Thereafter, a comparative characterization of the attributes of the tablets formulated was undertaken using Corn Starch, microcrystalline cellulose and rice husk as disintegrants. The granules were characterized for flow properties and tablets were evaluated for crushing strength, friability, disintegration and in vitro drug release. The tablets formulated with rice husk cellulose were found to be bioequivalent to those of corn starch which is a standard in comparative studies of disintegrants. Hence, rice husk cellulose is an alternative excipient to explore as a pharmaceutical excipient for limited resource economies.

Biochemical Changes in Albino Rats Exposed to Rice Husk Dusk at Abakaliki Rice Mill Industrial Area.

The effect of rice husk dust inhalation on some biochemical parameters was conducted on albino rats. Method: 100 albino rats were divided into five groups with each group containing twenty albino rats. Group A served as the control and were housed at the animal house away from rice dust while group B, C, and D were exposed to rice husk dust for two week, three weeks and four weeks respectively for dust inhalation. They were allowed access to rats feeds and deionized water ad libitium. Blood samples were collected from each group at the end of exposure by cardiac puncture. Glucose level was determined using the glucose reagent kit, acid phosphatase concentration was performed using reagent kits, creatinine and uric acid concentration was determined spectrophotometrically, the weight of the rats were recorded daily. Results: Result showed significant reduction in body weight of the exposed. The glucose level decreased significantly while the serum acid phosphatase and serum uric acid level showed a significant increase. Histological result showed various degrees of damage to the kidney of the exposed rats. Conclusion: We therefore conclude that rice husk dust inhalation induces glucose depletion, injury to the kidney and prostatic glands in the albino rat and impairs the renal function.

Characterization of Solid State Fermentation Culture Conditions for Growth and Mananase Production by Aspergillus niger USM F4 on Rice Husk in Tray System.

Aim: The study evaluated various fermentation conditions for the production of mannanase. Place and Duration of Study: Industrial Biotechnology Research Laboratory (IBRL), School of Biological Sciences, Universiti Sains Malaysia, 11800 Penang, Malaysia between May 2009 and September 2010. Methodology: Solid substrate fermentation was carried out in a shallow aluminum tray system (16 cm x 16 cm x 5 cm) for maximum mannanase production by Aspergillus niger USM F4 using rice husk as a substrate. Results: The maximum mannanase activity of 119.91 U/g substrate was achieved on the 6 days of cultivation when the optimized physical parameters were used (substrate thickness of 1.6 cm or equivalent to 80 g of 0.75 mm rice husk, moisture content to substrate ratio of 1:1 (w/v), cultivation temperature at room temperature (28±2ºC), inoculum size of 6x106 spores/ml and in static condition (no mixing during the fermentation process). The results showed an increment of about 30.79% of mannanase activity after the optimization (119.91 U/g substrate) compared to before optimization (91.68 U/g substrate). Conclusion: The results obtained from this study revealed that rice husk can be used as a substrate for mannanase production in solid state fermentation process.

Enraizamento de manjericão em diferentes substratos e doses de cinzas / Stem rooting of basil in different substrates and doses of ash

O trabalho teve como objetivo avaliar a influência de doses de cinzas em diferentes substratos no enraizamento de estacas de manjericão (Ocimum basilicum). O experimento foi conduzido em área do Núcleo de Capacitação e Pesquisa da Universidade Federal Rural da Amazônia, em Belém. Foi utilizado o delineamento experimental inteiramente casualizado, em esquema fatorial 2 x 5, constituído pelas combinações entre os fatores substratos (casca de arroz carbonizada e casca de castanha triturada) e acréscimo de cinzas (5 mL e 10 mL de cinza de casca de arroz, 5 mL e 10 mL de cinza de casca de castanha e sem cinza) com 4 repetições. Cada unidade experimental foi constituída por 10 estacas, num total de 400 estacas. Foram avaliadas as características percentual de enraizamento de estacas, número e comprimento de raízes. Não houve interações significativas entre os fatores avaliados (substrato e cinzas). Entre as características avaliadas o substrato casca de arroz carbonizada apresentou diferenças apenas no comprimento da raiz e no número de raízes, enquanto as dosagens de cinzas apresentaram diferenças apenas no percentual de enraizamento. O trabalho permitiu concluir que as dosagens de cinzas apresentaram efeito positivo sobre o enraizamento das estacas de manjericão, assim como o substrato a base de casca de arroz carbonizada propiciou melhores condições para o desenvolvimento das raízes. Assim, a casca de arroz é uma alternativa totalmente viável, pois além de apresentar características apropriadas para o enraizamento também possui baixo custo de aquisição, estando ao alcance de muitos produtores.

The study aimed to evaluate the influence of ash doses on different substrates on the stem rooting of basil (Ocimum basilicum). The experiment was conducted in the area of core training and research at the Universidade Federal Rural da Amazônia, in Belém, used a completely randomized design, factorial scheme 2 x 5 consisting of the combinations of the factors substrate (carbonized rice husk and bark brown ground) and increase ash (5 mL and 10 mL of rice husk ash 5 mL and 10 mL of husk ash and brown bark no gray) with four repetitions. Each experimental unit consisted of 10 cuttings, a total of 400 cuttings. Was evaluated the characteristics percentage of rooting, number and length of roots. There was no significant interaction between the factors evaluated (substrate and ash). Among the characteristics evaluated the carbonized rice showed only differences in root length and root number, while the levels of ash showed only differences in rooting percentage. The study revealed that the dosages of ash had a positive effect on rooting of cuttings of basil, as well as the substrate prepared with rice hulls provided the best conditions for root development. Thus, the rice husk is an alternative, as well as presenting features suitable for rooting also has a low cost of acquisition, being within reach of many producers.