Effects of fermentation chamber temperature on microbes and quality of cigar wrapper tobacco leaves.

The natural fermentation of cigar tobacco leaves usually utilizes natural temperature and humidity for fermentation. Cigars produced in China are often fermented in winter, and the low environmental temperatures can lead to slow heating of the tobacco stack, affecting the cigar tobacco leaves quality. This study aimed to determine the minimum chamber temperature required to initiate the process of fermentation for cigar tobacco leaves and to explore the impact of temperature on the microbial community of tobacco leaves. Here, the cigar variety "Dexue 1" were subjected to stacking fermentation under three temperature parameters (20 ℃, 27 ℃, 34 ℃). With an increase in environmental temperature, the temperature inside the stack of cigar leaves increased significantly, the protein, total sugar, starch, and total alkaloid content in fermented tobacco leaves decreased, and the aroma components and amino acid content increased. Microbial richness and community diversity associated with fermented tobacco were highest at chamber temperatures of above 27 ℃. The relative abundance of Chryseobacterium and Rhodococcus was significantly negatively correlated with protein, alkaloids, total sugar, and starch, and positively correlated with amino acids and aroma components. Chryseobacterium and Rhodococcus may be responsible for the degradation of macromolecular substances and the conversion of favorable aromatic substances, thus improving the tobacco leaves quality. This study demonstrated that increasing the fermentation chamber temperature above 27 ℃ was conductive to raising the inner-stack temperature, increased microbial diversity and aromatic quality, reduced the strength and irritation, and extremely enhanced the overall quality of fermented cigar tobacco leaves. KEY POINTS: • The environmental temperature of the fermentation chamber has a significant impact on the quality of tobacco • Temperature > 27 ℃ can initiate the process of cigar tobacco leaves fermentation and increase inner-stack temperature and microbial diversity and abundance • Chryseobacterium and Rhodococcus may be related to the degradation of macromolecular substances and the transformation of aromatic substances, thereby improving the quality of tobacco leaves.

Impact of Chamber/Annealing Temperature on the Endurance Characteristic of Zr:HfO2 Ferroelectric Capacitor.

The endurance characteristic of Zr-doped HfO2 (HZO)-based metal-ferroelectric-metal (MFM) capacitors fabricated under various deposition/annealing temperatures in the atomic layer deposition (ALD) process was investigated. The chamber temperature in the ALD process was set to 120 °C, 200 °C, or 250 °C, and the annealing temperature was set to 400 °C, 500 °C, 600 °C, or 700 °C. For the given annealing temperature of 700 °C, the remnant polarization (2Pr) was 17.21 µC/cm2, 26.37 µC/cm2, and 31.8 µC/cm2 at the chamber temperatures of 120 °C, 200 °C, and 250 °C, respectively. For the given/identical annealing temperature, the largest remnant polarization (Pr) was achieved when using the chamber temperature of 250 °C. At a higher annealing temperature, the grain size in the HZO layer becomes smaller, and thereby, it enables to boost up Pr. It was observed that the endurance characteristics for the capacitors fabricated under various annealing/chamber temperatures were quite different. The different endurance characteristics are due to the oxygen and oxygen vacancies in ferroelectric films, which affects the wakeup/fatigue behaviors. However, in common, all the capacitors showed no breakdown for an externally applied pulse (up to 108 cycles of the pulse).

Time-dependent efficacy and safety of tooth bleaching with cold plasma and H2O2 gel.

BACKGROUND: Hydrogen peroxide (H2O2) is the commonly used bleaching agent for teeth. But it is highly corrosive to teeth for the high concentration. The cold atmospheric pressure plasma has been witnessed a novel tooth bleaching technology and could help strengthen the bleaching effect when combined with H2O2. However, the efficacy and safety might highly correlated with processing time. The present study aims to evaluate the time-dependent efficacy and safety of tooth bleaching with cold plasma and H2O2 gel in vitro. METHODS: The H2O2 concentrations of the gel used in the study are 6%, 15%, 25% and 35%, respectively and the treatment time varies from 5 to 20 min. The tooth bleaching effect was evaluated by a Crystaleye Spectrophotometer and the overall change of the colorimetric value based on three independent measurements. Meanwhile, the microhardness, roughness and tooth temperature were evaluated. The surface morphology and the elemental composition were determined by scanning electron microscope and energy-dispersive X-ray spectroscopy. RESULTS: 5 min bleaching treatment contributed to 60% of the bleaching effect maximum, the 10 min effect was close to 15 min effect. Meanwhile, the microhardness reduced and roughness increased under a treatment which was longer than 20 min. Tooth pulp chamber temperature was keeping in a safe range within 20 min treatment. CONCLUSION: 5-10 min was the best treatment time from which we can get an ideal tooth bleaching effect and less influence on tooth enamel and pulp tissue when using cold plasma and H2O2 gel.

Can the Use of a Warm-Air Stream for Solvent Evaporation Lead to a Dangerous Temperature Increase During Dentin Hybridization?

PURPOSE: To analyze the effect of a warm-air stream for solvent evaporation on the temperature rise in the pulp chamber during dentin hybridization. MATERIALS AND METHODS: Dentin disks with thicknesses of 0.5, 1.0 and 1.5 mm were obtained from extracted human molars. A model tooth was set up with the dentin disks between a molar with an exposed pulp chamber and a crown with an occlusal preparation. A K-type thermocouple connected to a digital thermometer was placed in the molar root until it entered the pulp chamber and made contact with the dentin disks. After 10 s of adhesive application, solvent evaporation was performed for 10, 20, 30, and 40 s and the increase in temperature was monitored for 200 s after the warm-air stream began. RESULTS: The temperature increase was significantly influenced by the thickness of the dentin disks (0.5 mm = 1.0 mm > 1.5 mm). With respect to the duration of the warm-air stream, the temperature increase was as follows: 10 s < 20 s < 30 s < 40 s (p < 0.05). The highest temperature was found after 40 s with dentin disks that were 0.5 mm (16.6°C) and 1.0 mm (15.8°C) thick, whereas the lowest temperature increase occurred after 10 s with a dentin disk that was 1.5 mm thick (4.1°C) (p < 0.05). CONCLUSION: The temperature in the pulp chamber was strongly influenced by the dentin thickness and the duration of the warm-air stream. Thinner dentin and a longer duration of the warm-air stream both lead to a greater temperature increase in the pulp chamber.

The effect of cold chamber temperature on the cadaver's electrolyte changes in vitreous humor and plasma.

Determination of time since death is one of the important objectives of a medicolegal autopsy. The level of electrolytes present in the body fluids acts as a helpful indicator in this regard. Nowadays cold chambers are present in most of the autopsy centres where the body is stored for a variable period of time at a temperature which is different from the environmental temperature. This study was undertaken to know the effect of the cold chamber temperature on the changes in sodium, potassium and chloride levels of vitreous humor and plasma and also to estimate the time since death from the levels of these electrolytes. For this, the study subjects were exposed to the cold chamber temperature (in a range of +2 °C to +4 °C) for a variable duration of time before beginning the autopsy. The results obtained substantiate the fact that the temperature of the cold chamber has a significant effect on the change in vitreous humor potassium level. In subjects exposed to the cold chamber, there was a statistically significant negative correlation between the sodium and chloride levels of vitreous humor with time since death. The R-squared value for the regression equation to predict time since death from vitreous humor sodium level was found to be 0.0916 and was considered a significant predictor of time since death.

Analysis of Human Tooth Pulp Chamber Temperature After 670 nm Laser Irradiation: In Vitro Study.

OBJECTIVE: One of the limiting factors of employing laser radiation on dental therapies is the potential of causing thermal injuries to pulp tissues. The purpose of this study was to evaluate intra-chamber temperature increase on extracted human teeth exposed to 670 nm wavelength InGaAlP laser diode radiation. MATERIALS AND METHODS: In vitro intra-chamber temperature measurements of 12 standardized human teeth (incisors, canines, premolars, and molars; n = 3) were taken both before and after laser radiation. A type-K thermocouple fast-response thermocouple wire with a 0.5 mm diameter probe was inserted into the tooth pulp chamber (ICEL-Manaus-brand). The laser device Lasotronic-brand InGaAlP laser diode was used to irradiate tooth enamel, perpendicularly to the external surface for 30 sec, with power of levels of 340, 272, 204, 136, and 68 mW. The measurements were taken at three time points: 0, 30 sec, and 3 min after the laser irradiation. Measurements were repeated 24 h after removal and reinsertion of the probe in the pulp chamber. The temperature gradient (ΔT in °C) was calculated (ΔT = final temperature-initial temperature) for each group. Data of ΔT were statistically analyzed by two-way analysis of variance (ANOVA) at the 95% confidence level and compared by Tukey post hoc test (α = 0.05). RESULTS: ANOVA showed statistically significant differences to the interaction of factors (p < 0.05). The highest ΔT values obtained were observed to incisors with 340 mW, 272 mW; 204 mW of power (respectively 4.7°C, 4.2°C, and 3.1°C); and canines presented the lowest ΔT (0.8°C-0.3°C) with no influence of power output. CONCLUSIONS: Since the thermal increase was observed in this study, especially in incisors, attention should be paid to avoid pulpal damage.

Aumento de la temperatura intracámara pulpar durante el blanqueamiento con sistemas activados por luz: revisión de la literatura / Temperature increase intracameral pulp during bleaching with light-activated systems: review of the literature

Son varias las fuentes de energía utilizadas para acelerar la descomposición del peróxido de hidrógeno durante el blanqueamiento realizado en el consultorio. Durante su aplicación, los sistemas de blanqueamiento dental que utilizan fuentes de energía, aumentan la temperatura de los tejidos dentarios. Existen evidencias de que el aumento de la temperatura intracámara pulpar puede causar daño a este tejido. Este trabajo tuvo por objetivo presentar a través de una revisión de la literatura los diferentes tipos de luz utilizados para blanqueamiento y el calentamiento intracámara pulpar generado por estos. El aumento de temperatura intracámara pulpar crítico es considerado de 5,5º C. En estudios in vitro varios son los sistemas y combinaciones de tiempo que llegan o pasan esta temperatura. Antes de la utilización de estos sistemas el odontólogo debe conocer los riesgos existentes y leer las instrucciones de los fabricantes

To accelerate the decomposition of hydrogen peroxide during the in-office bleaching process, various energy sources can be used. During the application of these energy systems, an increase of temperature in teeth tissue has been reported. The temperature rise in the pulp might be harmful to this tissue. The objective of this work was to present through a literature review the different lights for an in-office bleaching and the resultant intrapulpal temperature rise produced by these lights. The critical temperature rise in pulp chamber is considered to be 5.5º C. On in vitro studies there are many systems and time combinations that achieved or passed this critical limit. Before the use of any energy source for the in- office bleaching, the dentist should be concerned about the existing risk and must read the manufacturer's instructions