教学课程资源库 更多>>

关键词： Rice straw composting   Aerobic fermenter   Bacterial community   Fugal community   High-throughput sequencing  

摘要： The influence of Streptomyces griseorubens JSD-1 on microbial community succession during rice straw composting in an industrial-scale fermenter was assessed by high-throughput sequencing technology. Compared to uninoculated control, JSD-1 inoculation effectively raised composting temperature and improved other maturation indices. JSD-1 inoculation increased the relative abundance of Actinobacteria in thermophilic phase and Firmicutes in cooling and maturation phases. At the genus level, JSD-1 inoculation increased the abundance of organic matter degrading bacteria (Virgibacillus) and lignocellulose degrading fungi (Chaetomium and Melanocarpus);while it decreased the abundance of pathogenic fungi (Geosmithia and Acremonium). Moreover, JSD-1 changed microbes that differed significantly and altered the key connecting nodes of microbial community. Organic matter and temperature were the most significant indices that had mutual influences on bacterial and fungal communities, respectively. This study demonstrated that JSD-1 was an effective inoculant on rice straw fast composting in the industrial-scale fermenter.

关键词： Biopolymer   Crosslinking   Biodegradable   Ecotoxicity   Packaging   Membranes  

摘要： Biodegradable chitosan films were produced using lactic and acetic acid solutions and glutaraldehyde as crosslinking agent by casting technique. The aim of this study was to evaluate the influence of different acids and the crosslinking on the characteristics and biodegradability of chitosan films. The films were analyzed through thickness, swelling degree, mechanical and thermal properties, chemical structure and biodegradability. The glutaraldehyde release was also evaluated. All films' properties are deeply affected by the acid type and glutaraldehyde crosslinking. Crosslinking reduced the swelling degree of films, also increasing their fragility. The glutaraldehyde release from the films to the simulant solutions was not observed after the incubation period. Through biodegradation tests, it was observed that the crosslinking does not prevent films' degradability but longer time is required. The qualitative analysis of ecotoxicity of the films suggests the possibility of composting the developed films. The films presented potential for application as membranes and in packaging, and different formulations can be used according to the desired final characteristics.

关键词： crystalline iron(III) chloride hydrate   microwave activation   chemical reactions   phase transformations   goethite  

摘要： We have studied physicochemical transformations of monoclinic crystalline iron(III) chloride hydrate particles in microwave fields. Microwave activation was carried out in air in two steps: first for 5 min at a power of 300 W and then for 2 min at 400 W. It was found using optophysical methods that the color, shape, and surface condition of the particles changed significantly. X-ray diffraction results pointed to active phase transformations. As a result of a series of chemical reactions, the crystalline [Fe(H2O)(6)]Cl-3 hydrate converted into a new phase, alpha-FeO(OH) (goethite), and more than 15% of the volume of the particles amorphized.

关键词： Lime treatment   Compressive strength   Embankment   Mesopores   Atmospheric exposure  

摘要： The long-term effect of lime treatment was evaluated on a 2.5% lime-treated experimental embankment after seven years of atmospheric exposure. The evaluation was done by comparison of (i) the mechanical performance of the field sampled specimens with laboratory cured specimens, and (ii) the physicochemical and microstructural properties of the samples from the lime-treated embankment with specimens obtained from an untreated embankment constructed near to it as a reference embankment. An average Unconfined Compressive Strength (UCS) level of 3.29 MPa was measured in the lime-treated specimens sampled from the core of the embankment. This UCS level was found to be comparable to the UCS of accelerated-cured specimens obtained at a laboratory scale. Thus, such levels of UCS can be expected after long-term in-situ curing. Scanning electron microscope images evidenced the contribution of the formation of cementitious bonding towards such UCS evolution in the lime-treated specimen. The persistence of the lime effect within the core of the embankment was confirmed by the presence of a pH greater than 11. However, a relative decrease in the pH and water content was observed in the upper layer compared to the core of the lime-treated embankment. This indicates that the effect of lime was lost in the upper layer under constant soil-atmosphere interaction and due to the development of vegetation mots. Pore structure observations made by Mercury Intrusion Pomsimetry (MIP) and Barrett-Joiner-Halendapore (BJH) methods highlight the formation of smaller pores (diameter < 3000 angstrom) under lime effect. These smaller pores have contributed towards the evolution of suction in the core-sampled specimens of the lime-treated embankment. This has led to the long-term water retention capacity of the lime-treated soil. BJH was able to detect mesopore-formation (25-500 angstrom) under the lime effect in a more precise manner compared to MIP. The evolution of mesopores was found to be coi

关键词： PCL   MWCNTs   magnetic properties   mechanical properties   in vitro degradation  

摘要： The fabrication of biodegradable magnetic poly(caprolactone)(PCL)/nanohydroxyapatite (nHA)/multiwalled carbon nanotube (MWCNT) composite scaffolds by thermally induced phase separation (TIPS) for bone regeneration is reported in this study. The magnetism tests completed on the porous matrices pointed to their ferromagnetic behavior. Bothin-vitrodegradation and mechanical properties are studied over eight weeks in a phosphate buffered solution (PBS) at 37 degrees C. The addition of MWCNTs at quantities of up to 5% modified the structural morphology of the composite, producing regular structures with repetitive patterns. As from that quantity, the electrostatic charge of the nanotubes within an aqueous solution was insufficient for acceptable distribution of the nanoparticles, by means of ultrasonic dispersion. It resulted in an acceleration of the degradation behavior that was clear from the mechanical properties that weakened by up to 20%. The thermal properties were also influenced in that they formed shorter chains, which could be ordered with greater ease, as a consequence of the ester hydrolysis process.

关键词： Geographical regions  

摘要： Analysis of physicochemical parameters, phenolic compounds, total reducing capacity, free radical scavenging, and antimicrobial potential was performed in 14 samples of honey from six different species of stingless bees from Brazil. The results of the physicochemical properties showed high moisture (24.28%-38.20% wt/wt), free acidity above 50 meq/kg for most honey samples, reducing sugars ranging from 58.79% to 73.01% (wt/wt), 5-hydroxymethylfurfural (5-HMF) below the limit of quantification (0.074 mg/L), diastase activity from <3 to 70.91 Gothe units, and electrical conductivity values varying from 0.13 to 0.84 mS cm(-1). In addition, 12 phenolic compounds were quantified, being taxifolin (

关键词： Regenerative medicine   Mesenchymal stromal cell   Pharmacologically active microcarriers   Polymer   Physicochemical properties   Cell behavior  

摘要： Polymeric, biodegradable, microspheres (MS) presenting a biomimetic surface of extracellular matrix (ECM) proteins are currently used for transporting cells and/or encapsulated proteins for regenerative medicine studies. They can be made of (lactic-co-glycolic acid) (PLGA) or of a more hydrophilic PLGA-P188 (Poloxamer188)-PLGA polymer allowing for the complete release of the therapeutic proteins. They promote stem cell adhesion, cell survival and differentiation after transplantation. Although the biological effectiveness of these microcarriers is established, a detailed understanding of the protein and cell interactions with the microcarrier surface remain unclear due to a lack of information of their surface properties. The aim of this study was to characterize the physicochemical properties of two polymeric MS systems and determine the effect of laminin and poly-n-lysine coated microcarriers on stem cell adhesion, survival and neuronal differentiation. The hydrophobicity and topography of PLGA MS promoted protein adsorption and the stem cells quickly adhered and spread on the surface of these microcarriers. In contrast less proteins adsorbed onto PLGA-P188-PLGA MS and although cells adhered to these microcarriers, they remained round and did not spread on their surface. Despite these earlystage differences, our results suggest that the nature of the MS does not strongly influence the long-term cell behavior. The cells exhibit the same cell number, differentiation profile and ability to secrete ECM molecules regardless of the type of microcarrier used. Likely the ECM molecules that form a microenvironment around both of these 3D microcarrier/cell constructs over time play a role in this converging cell behavior. We have thus furthered our understanding of the physicochemical properties of polymeric cell carriers affecting stem cell behavior to help tailor suitable microcarriers for neuroregenerative applications.

关键词： Gluten-free   Fish byproducts   Coconut flour   Tapioca flour   Storage period  

摘要： This study evaluated the use of innovative gluten-free coatings (tapioca and coconut flours) in fish nuggets, and their impact on the physicochemical and microbiological characteristics during its storage period (60 days) and the sensory properties. Fish nuggets coated with coconut flour (CCT-Nug) had reduced pick-up than control nuggets (CON-Nug), whereas cooking yield were similar for all coating types. Fish nuggets coated with tapioca flour (TPC-Nug) had reduced protein content, whereas CCT-Nug were low in fat content. The lipid oxidation and microbial growth were within normal levels throughout the period. The innovative coatings affected the fish nugget's color parameters with increases in the lightness (L*) and decreases in the redness (a*) and yellowness (b*) values. At the beginning of the storage period, CCT-Nug had a lower hardness value when compared to other treatments. These parameters were reflected in the sensory analysis, and TPC-Nug had low color scores, whereas CCT-Nug had low crispiness scores. The acceptance index (AI) was above 70% for both CON-Nug and CCT-Nug treatments. Finally, the use of coconut flour was considered more appropriate coating for gluten-free fish nuggets.

关键词： carboxymethylcellulose gum   elasticity module   extruded rice   lateral expansion   locust gum   solubility  

摘要： Extrusion is a composite process consisting of many different unit operations such as mixing, cooking, pasting, and molding. In this process, the raw material is forced through a tiny opening to be transformed into a product with a desired and unique shape, texture, color, and taste. In combination with different amounts and types of additives, this technique can result in functional food products for a broad range of people suffering from micronutrient deficiency. The hydrocolloid compounds are now employed to improve the texture and performance properties of many food products. Therefore, this study scrutinized the effects of carboxymethylcellulose and locust bean gums at different levels (0.5, 0.75, and 1%) alone or in combination with each other on chemical, physical, mechanical, and textural properties of extruded rice in comparison with the qualitative properties of the control rice. A completely random design was used along with three replications to analyze the test results. Then the means were compared through Duncan's multiple range test at (alpha = 5%). According to the results, addition of gums increased moisture, ash, total color difference, water absorption capacity, solubility, failure force, rupture energy, elasticity module, and toughness when reduced lateral expansion was compared to the control. Moreover, the addition of gums after the cooking process increased cooking loss, texture hardness, chewability, and elasticity of the specimens in comparison with the control. According to the results of pre- and post-cooking tests, the specimens containing locust (0.75%) and carboxymethylcellulose (0.75%) gums were the best treatments.

关键词： Uncertainty from sampling   Classic analysis of variance   Robust analysis of variance   Range Statistics   Physicochemical parameters   Diesel  

摘要： The result of a chemical measurement is consequence of a set of steps that begins with sample selection. The aim of this study was to evaluate the relative importance of the sampling in overall measurement uncertainty, taking as study case physicochemical measurements of diesel. The empirical method used was by duplicates, and the treatment of data sets was performed by four different statistical techniques: classic analysis of variance, robust analysis of variance and two different Range Statistics models. The choice must be backed by previous evaluation of data set in terms of normality, independence, presence of outliers and homogeneity of variance. It was found that Range Statistics produced most reliable results under different premises and for the variety of physicochemical parameters evaluated. Robust analysis of variance failed indicates proper influence of sampling even it is a test designed to work under the lack of some of the proper premises.