The effect of flue-curing procedure on the dynamic change of microbial diversity of tobaccos

The purpose of the study is to explore the effect of flue-curing procedure on the diversity of microbial communities in tobaccos and the dynamic change of compositions of microbial communities in the flue-curing process. It expects to provide a theoretical basis for the application of microbes in tobacco leaves and a theoretical basis and idea for optimization of the flue-curing technologies. By investigating tobacco variety K326, the tests were carried out for comparing the conventional flue-curing procedure and dry-ball temperature set and wet-ball temperature degradation flue-curing procedure. Based on the culture-independent approach and high-throughput sequencing procedure, the relationship between the flue-curing procedure for tobaccos and microbial communities in tobaccos was revealed by measuring the dynamic change of microbial communities. The results indicated that:(1) Relative to surface wiping method, washing method was more suitable for the sampling of microbes on the surface of tobacco leaves; (2) Dry-ball temperature set and wet-ball temperature degradation flue-curing procedure was more favorable for maintaining the microbial diversity of tobaccos; (3) Relative to bacteria of the tobaccos, the succession rule of the fungal communities in tobaccos was relatively steady; (4)Compared with bacterial community diversity, the fungal community diversity presented an obvious negative correlation with temperature and humidity during the flue-curing process. (5) The function of bacterial communities in tobaccos matched with the material transformation law of tobaccos, having a direct correlation on the flue-curing process. In short, Dry-ball temperature set and wet-ball temperature degradation flue-curing procedure can more favorably maintain the microbial diversity of tobaccos; moreover, the function of the tobacco system involved in microbes in tobaccos was closely related to the material transformation law of tobaccos in the flue-curing process. It validated that the bacteria in tobaccos play an important role in the flue-curing process of tobaccos.

Effect of Curing Reaction Types on the Structures and Properties of Acetylene-Containing Thermosets: Towards Optimization of Curing Procedure

High-temperature thermosets are usually prepared from resins containing alkynyl groups, and their properties depend much upon the curing process containing various types of curing reactions. However, how the curing process...

Effects of Rapid Microwave-Curing on Mechanical and Piezoresistive Sensing Properties of Elastomeric Nanocomposites

Carbon nanotubes (CNTs) have the unique ability to absorb microwave radiation and efficiently transfer the energy into substantial heat. When adequately dispersed in a thermoset polymer, such as polydimethylsiloxane (PDMS), the nanocomposite can be fully cured in seconds in a microwave oven rather than in hours in a convection oven. In this paper, cylindrical PDMS nanocomposites containing well-dispersed CNTs are fabricated by either microwave-curing or conventional thermal-curing. The mechanical, electrical, and piezoresistive properties of the fabricated samples are compared to understand the effects of different curing methods. Microwave-cured nanocomposites exhibit a significantly reduced compressive modulus for different CNT loadings. In addition, the electrical conductivity of microwave-cured nanocomposites is significantly enhanced over the thermally-cured counterparts. Experimental results demonstrate that the one-step microwave-curing procedure can improve the electrical conductivity of 1 wt% nanocomposites by almost 150 % over thermal-curing. However, their piezoresistive sensitivity remains remarkably similar, showing the potential for microwave-curing to replace thermal-curing for the manufacturing of highly flexible CNT-based nanocomposites.

Effect of Filler Content and Waiting time Before Light-Curing on Mechanical Properties of Dual-Cured Cement

Objective:: To investigate the effect of filler content and the time spent before light-curing on mechanical properties of dual-cured cement. Methods:: Experimental dual-cured resin cements were formulated with 60, 65 or 68wt% of filler. The viscosity of experimental cement was measured using a digital viscometer. Bar-shaped specimens (25 x 2 x 2 mm) were fabricated, while the light-curing was started immediately or 5 minutes after the insertion of cement into the mold (n = 7). A three-point bending test was performed and the values of flexural strength and elastic modulus were measured. The Vickers hardness of fractured specimens was measured on the surface of the cement. Data from viscosity were submitted to oneway ANOVA, while the data from mechanical properties were analyzed by two-way ANOVA. All pair-wise comparisons were performed using Tukey’s test (α = 0.05). Results:: The experimental cement with 68wt% of filler showed the highest viscosity and those with 60wt% showed the the lowest viscosity. Irrespective of the time spent before light-curing, the cement with 65wt% of filler presented the highest values of flexural strength and elastic modulus. The addition of 60wt% of filler resulted in the lowest elastic modulus, while 68wt% of filler resulted in lowest flexural strength. Regarding the hardness, the cement with 68wt% of filler showed the highest values, while there was no difference between 60 and 65wt% of filler. Conclusion:: Filler content affected the mechanical properties of the experimental cement and this effect did not depend on the waiting time before the light-curing procedure.

Regeneration of the damage periderm of potato tuber as a result of the temperature of curing

It is acknowledged that mechanical damage is a major cause of post-harvest losses of potato tubers and the curing is an indispensable process to increase resistance to excoriation. Furthermore, the use of lower curing temperatures is required to maintain the quality and prolong the durability of the tubers. However, they may not allow adequate regeneration of the damage periderm, besides this effect being variable among genotypes. The present study evaluates histological outcomes in the periderm derived from the mechanical damage through a simulation of excoriation, as it is the most common during the harvest and post-harvest stages. Therefore, the objective of this study was to determine the effect of reducing the curing temperature on the number of layers and on the thickness of the damage periderm of potato tubers of cv. Innovator. Histometric analysis of the cork, phellogen, phelloderm and the total periderm of tuber, was performed using the Image-Pro Plus software (MediaCybernetics) after curing for 15 days. The number of layers and thickness of each periderm structural layers were determined from six measurements for each repetition. After curing, there was no formation of the cork and phelloderm in the tubers conducted at 8 ° C under the excoriation treatment, while all components of the periderm were formed at 14 and 20 °C. At 8 and 14 °C, the phellogen differentiated similarly in tubers conducted at control and mechanical damage treatments, while at 20 °C the thickness did not differ in any component of the periderm. The phellogen at 14 and 20 °C did not differ in the number of layers and thickness. The visual aspect of the tuber injuries at 14 and 20 °C emphasizing the regeneration. It is concluded that the reduction of the curing temperature to 8 °C provided slower cell regeneration. However, it is possible to conduct the curing procedure at 14 °C, without compromising the formation of the damage periderm. The cultivar Innovator has rapid cell regeneration at higher curing temperatures, therefore it is recommended that the tubers of this cultivar be cured at 14 or 20 ° C. The study evaluates the mechanical damage through a simulation of the damage by excoriation. The however, for a better understanding of the formation of the damage periderm, it is interesting that other studies evaluate different types of damage, such as impact, comprehension and abrasion, in order to assess the regeneration capacity according to the damage of this cultivar.

The effects of curing technology on the rheological and organoleptic features of meat products

Meat products are important staple foodstuffs owing to their high protein, vitamin and mineral content. Meat plants do not only use traditional production technologies but also develop methods that preserve the nutritional value of meat or improve the texture and organoleptic features of meat products. These features play an important role in the consumer society. Consumers first meet the external features of meat and this experience influences their decisions. Our analyses compared a traditional and a new curing procedure. Besides organoleptic inspections, we analysed texture with a CT3 type Texture Analyser to obtain quantified information on the condition of meat samples in the various curing phases. We used our results to compare traditional and new curing procedures.

Continuous manufacturing of 3D patterned hybrid film via a roll-to-roll process with UV curing

A strategy for continuous fabrication of a microscale 3D-patterned hybrid composite film composed of alumina and acrylate resin was developed using roll-to-roll production. Conventional thermal curing was replaced with a UV curing procedure to facilitate rapid and economical processing. A seamless engraved soft urethane mold was first produced using a patterned metal roll. Subsequently, alumina and acrylate resin were cured on the engraved mold via UV irradiation to produce patterned hybrid films. The dispersion of alumina particles in acylate resin was enhanced by utilizing amine acrylate. Photopolymerization was measured using Fourier-transform infrared spectroscopy. The morphology of the soft engraved mold and the patterned hybrid film was investigated using scanning electron microscopy.

Effects of Filling Technique and Light Irradiation Distance on the Push-Out Bond Strength of Dual and Light Cured Core Materials in a Direct Core Build-Up

This study evaluated the effects of filling technique and light irradiation distance on the push-out bond strength of dual-cured (DC) and light-cured (LC) core materials to the root canal dentin. DC and LC core materials were filled with a bovine root canal post space of 8[Formula: see text]mm deep, and polymerized under two different filling procedures, i.e., an 8[Formula: see text]mm bulk filling (I) and two times of 4[Formula: see text]mm incremental filling (II), multiplying two different light irradiation distances (0 or 5[Formula: see text]mm) from top of the root canal. After 24[Formula: see text]h water storage, specimens were horizontally sectioned to obtain [Formula: see text][Formula: see text]mm thick core/dentin slices, and five slices were obtained for each root. After the slicing process, push-out tests were performed. Among all groups, the highest bond strength was observed in DCI5 (13.7 [Formula: see text] 4.3[Formula: see text]MPa), whereas the lowest was observed in LCI0 ([Formula: see text][Formula: see text]MPa). Consequently, the recommended curing procedure between DC and LC core materials differed. Combination of LC core material with incremental filling technique and of DC core material with bulk filling technique indicated higher bond strength. Higher bond strength was measured at a 5[Formula: see text]mm light irradiation distance for both LC and DC core materials.

Dielectric Properties of Epoxy/Anhydride System in Long-Term Storage

The change of dielectric properties of epoxy/anhydride systems during eleven months storing was investigated. Test systems were bisphenol-A epoxy cured by different content of methyl-hexahydrophthalic anhydride with a slow cooling process across Tg range included in their curing procedure to reduce residual stress. The results showed all the systems’ dielectric constant and dielectric loss angle tangent had a trend of down then up. The highest decreasing amplitudes were about 4% and 10% respectively. Possible explanations for these phenomena were proposed, and then some preliminary investigations were carried out like DSC and IR.

A novel DOPO-containing flame retardant for epoxy resin

A novel halogen-free flame retardant (6,6′-(((methylenebis(4,1-phenylene))bis(azanediyl))bis((4-hydroxy-3-methoxyphenyl)methylene))bis(6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide)(DP-DDM))) was synthesized via a one-pot procedure based on the Pudovik reaction between 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide and imine directly resulting from 3-methoxy-4-hydroxybenzaldehyde with 4,4′-methylenedianiline (DDM). The thermal curing behaviors of epoxy resins with different contents of DP-DDM were investigated by differential scanning calorimetry under a nonisothermal condition, aimed to suggest an optimized curing procedure in accordance with the property of DP-DDM. These DP-DDM-modified epoxy thermosets under optimized curing procedure showed high glass transition temperature and thermal degradation activation energy. Moreover, their high flame-retarding performance has been found: the epoxy thermosets with a relatively low addition amount of DP-DDM (on account of the phosphorus content of 0.75 wt%) can reach UL 94 V-0 (Instrumental analysis and measurements) rating with limiting oxygen index value of 34.5.