Moderate Heat Treatment Research Articles

The potential use of acylglycerols on the thermal inactivation of lactic acid bacteria for the manufacture of long-life fermented products

The effect of acylglycerols on the thermal inactivation of lactic acid bacteria used in the production of fermented products was studied. The starting point was the observation of an increase in thermal sensitivity in the presence of an emulsifier based on mono- and diacylglycerols in the culture medium. Analysis of the emulsifier showed that monoacylglycerols were the compounds responsible for this effect, with monopalmitin being the main contributor. Monostearin, on the other hand, showed significantly less potentiating effect. Interestingly, monoacylglycerols showed a greater bactericidal effect when used individually than when used in combination. On the other hand, the rate of thermal inactivation observed in reconstituted skim milk emulsions was lower than in peptone water emulsions, showing that the presence of proteins and colloidal particles increased the resistance of bacteria to heat treatment. With respect to pH values, a reduction in pH from 6.6 to 5.5 promoted an increase in the rate of thermal death. However, at pH = 5.5, the enhancing bactericidal effect was only detectable when the heat treatment was performed at low temperatures but not at high temperatures. This finding is of interest, since it will allow the design of moderate heat treatments, combining the use of temperature with the addition of acylglycerols, to prolong the shelf life of products fermented with lactic acid bacteria, and minimizing the destruction of desirable compounds that were obtained by the fermentation process.

SnSe nanoplates swallowed in carbon nanofibers as the self-standing anode for lithium-ion and sodium batteries with enhanced performance

SnSe is a promising anode candidate for both lithium-ion and sodium batteries (LIBs and SIBs) with high theoretic capacities, low toxicity and abundant resources. However, it suffers a short cycling life due to the poor conductivity and volume expansion when used as anode material. To improve its Li/Na storage properties, SnSe nanoplates are encapsulated in carbon nanofibers formation a 3D conductive network via a moderate electrostatic spinning and heat treatment. The modified SnSe anode exhibits textile-like feature with extensively mechanical flexibility, and was directly used as anode without and additives for both LIBs and SIBs. It delivers an excellent cycle performance with a high capacity (598 mA h g−1 after 400 cycles for LIBs and 240 mA h g−1 after 250 cycles for SIBs), which are modify enhanced comparing with reported works. The effective strategy can provide an available approach to build self-standing and flexible architecture, which is beneficial for the design of electrode materials for SIBs.

Flexural behaviour of cold-formed steel square and rectangular hollow sections with moderate heat-treatment

This paper discusses the flexural behaviour of cold-formed square and rectangular hollow steel sections (SHSs and RHSs) with subsequent heat-treatment through experimental and numerical investigations. Firstly, an experimental programme comprising tensile coupon tests on flat and corner regions and three-point bending beam tests were conducted. A total of 12 specimens were tested under monotonic bending loads, covering a variety of section slenderness. Failure modes, moment-rotation curves and plastic hinge lengths have been evaluated highlighting the effect of the web-flange interaction on rotation capacity. Successively, experimental results were combined with numerical FE results to assess the corresponding moment and deformation capacities. Current cross-section classification limits given in Eurocode 3 and AISC 360–16 were assessed and new limits has been proposed.

Heat treatment of quinoa (Chenopodium quinoa Willd.) albumin: Effect on structural, functional, and in vitro digestion properties.

Quinoa seeds are rich in protein, polyphenols, phytosterols, and flavonoid substances, and excellent amino acid balance that has been revisited recently as a new food material showing potential applied in fitness and disease prevention. Heat treatment is one of the most effective strategies for improving the physiochemical characteristics of a protein. However, research examining the effects of temperature on quinoa albumin (QA) properties is limited. In this study, QA was subjected to thermal treatment (50, 60, 70, 80, 90, 100, and 121°C). SDS−PAGE revealed that QA is composed of several polypeptides in the 10−40 kDa range. Amino acid (AA) analysis showed that the branched-chain amino acids (BCAAs), negatively charged amino acid residues (NCAAs), and positively charged amino acids (PCAAs) contents of QA were more than double that of the FAO/WHO reference standard. Additionally, heating induced structural changes, including sulfhydryl-disulfide interchange and the exposure of hydrophobic groups. Scanning electron microscopy demonstrated that the albumin underwent denaturation, dissociation, and aggregation during heating. Moreover, moderate heat treatment (60, 70, and 80°C) remarkably improved the functional properties of QA, enhancing its solubility, water (oil) holding capacity, and emulsification and foaming characteristics. However, heating also reduced the in vitro digestibility of QA. Together, these results indicate that heat treatment can improve the structural and functional properties of QA. This information has important implications for optimizing quinoa protein production, and various products related to quinoa protein could be developed. which provides the gist of commercial applications of quinoa seeds for spreading out in the marketplace.

Selective isolation, antimicrobial screening and phylogenetic diversity of marine actinomycetes derived from the Coast of Bejaia City (Algeria), a polluted and microbiologically unexplored environment.

The current study aimed to evaluate the occurrence of actinomycetes in the Coast of Bejaia City using selective isolation, as well as their bioactivity and phylogenitic diversity. Different selective media and methods were used, leading to the isolation of 103 actinomycete strains. The number of strains was influenced by isolation procedures and their interactions based on a three-way ANOVA and a post hoc Tukey test, which revealed that using M2 medium, dilution of samples followed by moderate heat treatment, and sampling at 10-20m yielded the highest numbers of actinomycetes. The isolates were screened for their antimicrobial activity against human pathogenic microorganisms using agar and well diffusion methods. Of all the isolates, ten displayed activity against at least one Gram-positive bacterium, of which P21 showed the highest activity against Staphylococcus aureus, Methicillin-resistant S. aureus and Bacillus subtilis, with a diameter of 32, 28 and 25mm respectively. Subsequently, active isolates were assigned to Streptomyces spp. and Nocardiopsis spp. based on 16S rRNA gene sequencing, including a putative new Streptomyces species (S3). The phenotypic characteristics of the P21strain were determined, and interesting enzymatic capacities were shown. The recovery of actinomycetes along the Coast of Bejaia City was influenced by the isolation procedure. Ten strains displayed interesting antibacterial activity against Gram-positive bacteria, of which the P21 strain was selected as the most active strain. This work provides a new insightinto the occurrence of actinobacteria in the Coast of Bejaia. It suggests also that polluted environments such as Bejaia Bay could provide access to interesting actinomycetes as sources of antibiotic leads.

Improved production of gamma-cyclodextrin from high-concentrated starch using enzyme pretreatment under swelling condition

High substrate viscosity during the production process suppressed the formation of gamma-cyclodextrin (γ-CD) from starch. Although liquefaction can be carried out by enzymes with high temperature optimum, some CGTases of interest are not suitable due to loss of activity at the gelatinization temperature. In order to apply a gamma-cyclodextrin glucosyltransferase (γ-CGTase) with an optimum temperature of 50 °C to the liquefaction of 10% w/v cassava starch, an improved process combining moderate heat treatment (30 °C increased to 70 °C) with enzymatic treatment was established. The substrate viscosity dropped from 2456 to 23 cP after the pretreatment, and the rate of γ-CD production increased from 10.43 to 26.34%. This process was further applied to the liquefaction of 30% w/v cassava starch, and the pretreated substrate was finally converted into 21.81% γ-CD. In general, evaluation indicators and basic principles of starch pretreatment were established, providing a reference for the production of γ-CD.

Effect of Heat Treatment on the Physic-Mechanical Characteristics of Eucalyptusurophylla S.T. Blake.

Eucalyptus plantations wood have great potential application in high quality solid wood product. In order to improve the overall characteristics, heat treatments (HT) were carried out using Eucalyptus urophylla S.T. Blake wood at 150, 170 and 190 °C, for 2 and 4 h, separately. The effects of HT on physical and mechanical properties, wood color, dimensional stability and chemical change were investigated. The results indicate that: Mass loss (ML) of wood at a moderate temperature of 150 °C was small, but increased remarkably when temperature exceeds 170 °C. A maximum ML of 5.83% was observed at 190 °C/4 h; the velocity of water vapor adsorption and equilibrium moisture content (EMC) of HT wood decreased significantly, and varied considerably with treating severity; absolute dry density of HT wood decreased, presenting a similar tendency with ML, but the reduction was greater than ML; HT reduced the tangential and radial swelling ratio and swelling coefficients of wood, and improved the dimensional stability by 71.88% at 190 °C; modulus of rupture (MOR) and modulus of elasticity (MOE) of HT wood varied significantly in severer conditions, but there were no obvious changes in a moderate conditions at 150 °C; there was a slight color change at 150 °C, but wood color became more dark and uniform with treating severity; HT decreased the relative content of hydroxyl groups in wood components, improving wood dimensional stability. Color change of wood may be caused by variations of chromophoric groups and its own structure of lignin due to HT. Moderate temperature HT at 150 °C improved dimensional stability and color uniform of wood, but without reducing mechanical stress. This is a practical HT condition for Eucalyptus urophylla S.T. Blake.

Additively manufactured Haynes 282: effect of unimodal vs. bimodal γʹ- microstructure on mechanical properties

This study examines the effects of lower-than-nominal heat treatment (HT) temperatures and cooling rates —possible during the treatment of larger components— on microstructure and tensile properties Haynes 282 manufactured via laser powder bed fusion (L-PBF) additive manufacturing process. Two main HT schedules, i.e., conventional treatment and its lower temperature variants were performed. The microstructural evolution at each step of the HTs was tracked and compared. It was shown that solution temperature of a wide range (1062–1146 °C) could moderately remove the as-solidified dendritic microstructure resulting in similar distribution of grain boundary (GB) carbides. In addition, the lower temperature double aging process resulted in a bimodal γ′-precipitates consisting of both nano-sized secondary γʹ- and large primary (>∼100 nm) γ′-precipitates, while the conventional aging gave rise to a unimodal γ′-precipitates with precipitates of diameter ∼60 nm. Owing to the bimodal γ′-precipitates and a similar GB carbide distribution, the low temperature HTs resulted in comparable tensile properties to the conventional HT despite having much larger γ′-precipitates. The results imply that moderate HT temperature deviations due to excessive component size, such as lower temperatures and slower heating/cooling rates, does not negatively impact the mechanical properties of L-PBF Haynes 282.

Moderate temperature and UV‐C light processing of Uruset apple juice: Optimization of bioactive components and evaluation of the impact on volatile profile, HMF and color

AbstractIn this study, the aim was primarily to optimize the process conditions for the enrichment of bioactive components in Uruset apple juice with UV‐C light and moderate heat treatment. UV‐C light was applied to Uruset apple juice at five different UV‐C doses between 84.6 and 169.1 mJ/cm2 using a batch benchtop UV‐C reactor and five different temperatures (40, 45, 50, 55, and 60°C). Total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (1,1‐diphenyl‐2‐picrylhydrazyl [DPPH]), cupric reducing antioxidant capacity (CUPRAC), ascorbic acid and total anthocyanin content (TAC) were evaluated for optimization (response surface methodology) of process conditions. The effect of moderate temperature‐UV‐C light (40°C and 97.33 mJ/cm2) on the HMF (hydroxymethylfurfural) content, optical microstructure and color value of the Uruset apple juice (UUA), fresh Uruset apple juice (FUA) and pasteurized Uruset apple juice (PUA) were then evaluated. At the end of the optimization, TPC (852.83 mg GAE/L), TFC (539.91 mg CE/L), DPPH (71.97%), CUPRAC (79.17%), ascorbic acid (5.96 mg/100 mL), and TAC (211.71 mg/L) were determined. The PUA sample obtained a higher score than the UAA sample in terms of total color change (ΔE). As a result, UV‐C light and moderate heat treatment of Uruset apple juice was found to be successful.Practical ApplicationsFresh apple juices are important sources of bioactive components such as phenolics, carotenoids, vitamin C, and organic acids. The results provided in the study by the combination of moderate heat and UV‐C light could be suggested as an alternative pasteurization process in order to prevent and/or reduce the negative effect on nutritional and sensorial properties of juice of using the heat pasteurization process alone. The number of studies related to preservation of fresh apple juice in terms of Uruset apple variety is fairly limited. Furthermore, the reactor used in the study could be transferred to the fruit juice industry after a scaling‐up feasibility study.

Phycocyanobilin-modified β-lactoglobulin exhibits increased antioxidant properties and stability to digestion and heating

β-lactoglobulin (BLG) is a major whey protein with numerous techno-functional properties desirable for the food industry. Phycocyanobilin (PCB), a bioactive pigment of Arthrospira platensis with health-promoting effects, covalently binds to BLG at physiological pH. This study investigated the effects of this covalent modification on BLG functional properties. The BLG–PCB adduct possesses enhanced antioxidant properties, and bound PCB protects BLG against free radical-induced oxidation. Despite the similar thermal stabilities of BLG and BLG–PCB, BLG–PCB is less susceptible to covalent and noncovalent aggregation under moderate heat treatment (63 °C, 30 min). Blocked thiol group and reduced hydrophobicity due to hindering of hydrophobic residues by bound PCB, as well as the heat-induced transition of β-sheet to α-helix, contributed to the low susceptibility of BLG–PCB to aggregation. BLG–PCB has a higher resistance to pepsin and pancreatin digestion than BLG and unaltered IgE-binding properties. The improved functional properties of BLG–PCB make it a useful ingredient in the food industry.

Effects of impregnation and heat treatment on density, bending and compression properties of black pine (Pinus nigra Arnold) wood

ABSTRACT This study aims to study the improvement in the properties of heat-treated wood material by impregnation. For this purpose, black pine (Pinus nigra Arnold) wood specimens were modified in two stages: impregnation with 1%, 3% and 5% of diammonium phosphate (DAP) and sodium carbonate (SC) compounds followed by heat treatment at four different temperatures. Test specimens were pre-treated with solutions of different pH values of either DAP or SC solutions according to the immersion method and they were exposed to heat treatments at 150°C, 170°C, 190°C and 210°C for 3 h. Some physical and mechanical properties were determined in combined treated specimens with air-dried density, compression strength parallel to grain (CS) and bending strength (MOR). The test results indicated that, as regards the effect of the heat treatment, the mechanical strength decreased due to the increase in temperature, while the losses in the CS were fewer than those of the MOR. In addition, generally combined treatments increased the mechanical properties of the specimens, especially at lower and moderate heat treatment temperatures. Moreover, the SC compound showed more favorable results against the reducing effect of the heat treatment on mechanical strengths.

Hygroscopicity, degradation and thermal stability of isolated bamboo fibers and parenchyma cells upon moderate heat treatment

Hygroscopicity, degradation and thermal stability of isolated bamboo fibers and parenchyma cells upon moderate heat treatment

Study of the impacts of electro-activated solutions of calcium lactate, calcium ascorbate and their equimolar mixture combined with moderate heat treatments on the spores of Bacillus cereus ATCC 14579 under model conditions and in fresh salmon

Widespread in very diverse environments, the spores of Bacillus cereus are highly resistant to hostile conditions and can contaminate a huge variety of food products, posing a potential health hazard to consumers. Given this significant risk, the objective of this research work was to study the impacts of electro-activated solutions (EAS) made with calcium ascorbate, calcium lactate, and their equimolar mixture on Bacillus cereus ATCC 14579 spores in model conditions and food matrix, the fresh Atlantic salmon. The model conditions consisted of a direct application of the EAS to the spores, which avoided any interference with factors external to those of the solutions. Salmon was chosen as a food model because it is a product sensitive to bacterial spoilage and can be eaten raw. To achieve this, the solutions were prepared by electro-activation using an electric current with an intensity of 750 mA for 30 min, resulting in mean pH values of 1.94 ± 0.15–2.16 ± 0.01 and titratable acidity of 0.102 ± 0.001–0.109 ± 0.001 mol/L, depending on the type of solution. These conditions were chosen because of their excellent antibacterial efficacy previously demonstrated against vegetative cells of B. cereus. The results showed high sporicidal activities of the EAS against B. cereus with a 7 to 9 log reduction, using an initial spore population of 109 CFU/mL, depending on the conditions evaluated, namely: in direct contact (2–30 min), in salmon used as a food matrix (2–7 min), and in combination with moderate heat treatments from 60 to 90 °C (0.5–2 min). In addition, it was observed that the sporicidal capacity of the EAS increased with temperature and the contact time. Otherwise, analysis of the color and lipids of the salmon have not shown any major impacts of the use of EAS as a rinsing solution for this highly perishable food. Furthermore, micrographs taken by scanning and transmission electron microscopy revealed the destructive effects of the EAS used in the vital structures/components of the spores. In general, this study has demonstrated that the electro-activation technology is effective in producing EAS capable of destroying/inactivating B. cereus spores and that they can be used for the improvement of food safety and preservation.

Semi-industrial production of a minimally processed infant formula powder using membrane filtration

Infant formula (IF) is submitted to several heat treatments during production, which can lead to denaturation or aggregation of proteins and promote Maillard reaction. The objective of this study was to investigate innovative minimal processing routes for the production of first-age IF powder, thus ensuring microbial safety with minimal level of protein denaturation. Three nutritionally complete IF powders were produced at a semi-industrial scale based on ingredients obtained by fresh bovine milk microfiltration (0.8 and 0.1-µm pore size membranes). Low-temperature vacuum evaporation (50°C) and spray-drying (inlet and outlet temperatures of 160 and 70°C, respectively) were conducted to produce the T- formula with no additional heat treatment. The T+ formula was produced with a moderate heat treatment (75°C for 2 min) applied before spray-drying, whereas the T+++ formula received successive heat treatments (72°C for 30 s on the milk; 90°C for 2-3 s before evaporation; 85°C for 2 min before spray-drying), thus mimicking commercial powdered IF. Protein denaturation and Maillard reaction products were followed throughout the production steps and the physicochemical properties of the powders were characterized. The 3 IF powders presented satisfactory physical properties in terms of aw, free fat content, glass transition temperature, and solubility index, as well as satisfactory bacteriological quality with a total flora <103 cfu/g and an absence of pathogens when a high level of bacteriological quality of the ingredients was ensured. Protein denaturation occurred mostly during the heat treatments of T+ and T+++ and was limited during the spray-drying process. The IF powder produced without heat treatment (T-) presented a protein denaturation extent (6 ± 4%) significantly lower than that in T+++ (58 ± 0%), but not significantly different from that in T+ (10 ± 4%). Although T- tended to contain less Maillard reaction products than T+ and T+++, the Maillard reaction products did not significantly discriminate the infant formulas in the frame of this work. The present study demonstrated the feasibility of producing at a semi-industrial scale an infant formula being bacteriologically safe and containing a high content of native proteins. Application of a moderate heat treatment before spray-drying could further guarantee the microbiological quality of the IF powders while maintaining a low protein denaturation extent. This study opens up new avenues for the production of minimally processed IF powders.

NMR-based metabolomic investigation of antimicrobial mechanism of electrolysed water combined with moderate heat treatment against Listeria monocytogenes on salmon

Heat and acidic electrolysed water (AEW) are considered effective for inactivation of microorganisms. While a previous study elucidated their bactericidal mechanism on Listeria innocua through metabolomics in vitro, the fundamental mechanism for inaction of L. monocytogenes using this method in food system is poorly understood. This work determined the survival population and injury of three L. monocytogenes strains (SSA81, LM44, and LM3) inoculated on salmon under heat (60 °C) and AEW (100 mg/L available free chlorine, pH 2.42, oxidation reduction potential 1182 mV) treatments, when applied alone or in combination. The bactericidal mechanism was explored by utilising nuclear magnetic resonance (NMR) and multivariate data analysis. Our results indicated that the individual heat and AEW treatment led to 0.4 and 1.2 log CFU/g reductions of L. monocytogenes, respectively. The combined treatment of heat and AEW resulted in notable reductions which were 2.1–2.2 log CFU/g for L. monocytogenes. More than 25%, 35%, and 55% injury of L. monocytogenes were observed under heat, AEW, and the combined treatment, respectively. Overall, 43 metabolites were characterised in three strains. Short time heat might activate protective system of the cells by accumulating amino acids and organic acids. AEW resulted in the reductions of metabolites due to oxidative and acid stress. In the combined treatment, AEW played the main role and its bactericidal ability was strengthened by heat. Significant decreases of Val, Leu, Tyr, and Trp were detected in all strains under the synergic stress of heat and AEW (P < 0.05). There were 15, 7, and 6 pathways, mainly included amino acid, energy, and carbohydrate metabolisms, changed significantly under the combined treatment for SSA81, LM44, and LM3, respectively. The strain LM3 presented the strongest resistance to oxidative stress by the enhancement of Glu decarboxylase system, whereas this compensatory pathway was diminished in SSA81 and LM44. These findings suggest that the bactericidal mechanism can be well explained by disturbed pathways.

Impact of thermosonication pretreatment on the production of plant protein-based natural blue colorants

The increase in the consumption of natural and non-dairy products has boosted the worldwide food colorant industry. Thus, the use of non-animal protein sources to produce natural blue compounds from the cross-linking between primary amines and genipin extracted from unripe Genipa americana L. pulp was evaluated in this study. Plant extracts obtained from white rice, oat, peanut, and almond were examined as amine suppliers, extraction media, and carrier systems for the blue compounds. The four plant extracts were thermosonicated at 70 °C and 400 W for 3 min and then subjected to ultrasound-assisted extraction of genipin from unripe genipap pulp at 300 W for 6 min. Thus, this study aimed to evaluate the effects of thermosonication pretreatment and plant material on natural blue colorant production. Four new blue plant-based colorants were produced. Protein availability was the most significant limiting factor in the blue color formation reaction. The acoustic cavitation associated with moderate heat treatment during the thermosonication promoted the rupture of fat globules and starch gelatinization. Furthermore, thermosonication pretreatment showed promising to improve the kinetic stability of the natural blue colorants.

Identifying ranges of combined lime and heat treatments to achieve biosolids stabilization fecal coliform targets

To ensure safe reuse, biosolids are stabilized to reduce pathogens, odor, and volatile solids. Stabilization by lime addition have high material costs, high transportation costs, and loss of ammonia. Decreasing required lime additions would improve the sustainability of biosolids reuse. This study examined combining lime and heat treatment to reduce lime additions needed for required fecal coliform destruction. In contrast to the current best management practice requiring a pH of 12, fecal coliform reduction for final concentrations <1000 MPN/g (where MPN is most probable number) was achieved with pH as low as 10 when combined with a short (1-h) incubation at 60 °C. Analysis of D-values (the time required to destroy 1-log fecal coliform) supported a synergistic treatment response at moderate pH and heat treatments. Samples receiving higher temperature treatments had lower specific oxygen uptake rates, suggesting that readily-available carbon was lost during heat treatment. Samples with lower lime additions had higher final ammonia concentrations, which is a desired characteristic for biosolids reclaimed as a fertilizer. The study demonstrated that optimizing combined lime and heat stabilization can improve beneficial reuse as a means toward enhancing environmental sustainability and improving the circular economy.

СИНТЕЗ И ИССЛЕДОВАНИЕ СОПОЛИМЕРОВ ЭТИЛЕНА С ГЕКСЕНОМ-1, МОДИФИЦИРОВАННЫХ АППРЕТИРОВАННЫМИ НАНОВОЛОКНАМИ g-Al2O3 (НАФЕН), С ПОВЫШЕННОЙ СТОЙКОСТЬЮ К ТЕРМООКИСЛИТЕЛЬНОЙ ДЕСТРУКЦИИ

Here we report the study on synthesis and characterization of nanocomposites obtained by in situ catalytic polymerization of ethylene and hexene-1 on metallocene catalyst in the presence of dispersed surface-functionalized -Al2O3 nanofibers (Nafen). It has been determined that surface treatment of Nafen nanofibers with organosilanes allows to obtain stable nanoscale dispersions under ultrasonication. It has been shown that nanocomposites based on copolymers of ethylene with hexene-1 demonstrate improved resistance to thermal oxidative degradation in comparison with nanocomposites based on copolymers of ethylene with propylene, while the influence of the silane chemistry on the mechanical characteristics in these nanocomposites is less pronounced. The best mechanical characteristics were achieved for nanocomposite with Nafen treated with trimethoxyvinylsilane. The melt flow index drop is observed after moderate heat treatment or combined temperature/humidity.

Investigation of the spectrally resolved TL signals of natural quartz single crystals sensitized by high-dose of gamma-radiation and moderate heat-treatments

This study examines the thermoluminescent emission of quartz whose existence can be registered with 1 mGy test-doses. Samples originated from three crystals were sensitized using the combined effect of gamma radiation and heat-treatments. The glow curves were registered under five optical setups to collect emissions from ultraviolet to yellow-orange bands. The emissions were scrutinized using a computerized deconvolution method. After sensitization, the activation energies of trapping states increased, and the violet/blue emissions exceeded the near-ultraviolet emission in the whole glow curve. The possibility to remove and restore the sensitization effect and the existence of strong emissions above 350 °C indicates that the rise in TL sensitivity occurs when competition between active and deep traps is annihilated. The narrow distribution of activation energies and the subtle changes in band emissions suggest that TL production in quartz consist of localized transitions involving different energetic levels of the same traps and recombination centers.

Temperature-Dependent Electrical Properties of Graphitic Carbon Schottky Contacts to β-Ga₂O₃

Graphitic (sp <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -rich) carbon Schottky contacts to (201) β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> were fabricated using sputtering and energetic ion deposition with and without the use of an oxygen plasma. As-deposited contacts exhibited room temperature effective barrier heights between 0.80 and 1.20 eV, depending on the deposition technique. After moderate heat treatment (595 K in N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) the work function of the oxygenated graphitic contacts increased by 0.5-0.8 eV. This resulted in a permanent increase in barrier height (up to 1.6 eV) and a corresponding 3-4 orders of magnitude increase in current rectification (at ±3 V). The barrier heights of the heat-treated oxygenated graphitic Schottky contacts agree well with the Mott-Schottky model, suggesting an absence of Fermi level pinning at the C/β-Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> interface.