Induction Temperature Research Articles

Analisis Pengaruh Holding Time terhadap Sifat Mekanis dan Struktur Mikro pada Proses Induction Tempering Batang Piston Baja SCM 420 H

Selection of materials connecting rod for a component or structure usually involves several aspects, there are aspects of specific strength, stiffness, lightweight, noncorrosive materials and resistance or age. In the manufacturing process connecting rod always give heat treatment such as Normalizing, Carburizing, and Induction Tempering. In the process, Induction Tempering has a big problem in hardness after the process, not stable and liable to over from standard. Process condition of tempering induction temperature in 650~700 C at 1 atm pressure, & holding time variation at 5, 10, 15, and 20 seconds. Kind of tests such as bending test, magna-flux, hardness, and structure micro. Bending test report fiber flow is straight, not broke because not found micro crack portension at body connecting rod. Hardness test result min point 23 HRC and max point 39,2 HRC base on standard range 25~44 HRC. The results of surface morphological observation show that the martensite phase causes hardness value to increase.

High-efficiency expression of Sulfolobus acidocaldarius maltooligosyl trehalose trehalohydrolase in Escherichia coli through host strain and induction strategy optimization

Maltooligosyl trehalose trehalohydrolase (MTHase, EC 3.2.1.141) catalyzes the release of trehalose, a novel food ingredient, by splitting the α-1,4-glucosidic linkage adjacent to the α-1,1-glucosidic linkage of maltooligosyl trehalose. However, the high-yield preparation of recombinant MTHase has not yet been reported. In this study, a codon-optimized synthetic gene encoding Sulfolobus acidocaldarius MTHase was expressed in Escherichia coli. In initial expression experiments conducted using pET-24a (+) and E. coli BL21 (DE3), the MTHase activity was 10.4U/mL and a large amount of the expression product formed inclusion bodies. The familiar strategies, including addition of additives, co-expression with molecular chaperones, and expression with a fusion partner, failed to enhance soluble MTHase expression. Considering the intermolecular disulfide bond of MTHase, expression was investigated using a system comprising plasmid pET-32a (+) and host E. coli Origami (DE3), which is conducive to cytoplasmic disulfide bond formation. The MTHase activity increased to 55.0U/mL, a 5.3-fold increase. Optimization of the induction conditions in a 3-L fermentor showed that when the lactose was fed at 0.2g/L/h beginning at an OD600 of 40 and the induction temperature was maintained at 30°C, the MTHase activity reached a maximum of 204.6U/mL. This is the first report describing a systematic effort to obtain high-efficiency MTHase production. The high yield obtained using this process provides the basis for the industrial-scale production of trehalose. This report is also expected to be valuable in the production of other enzymes containing disulfide bonds.

Elucidation of the factors affecting poor flowering in litchi (Litchi chinensisSonn.) and measures to overcome

It is a major concern of litchi growers in many locations that yields are often irregular and frequently below the trees bearing capacity. Poor litchi flowering is a worldwide problem, especially in regions where the weather during the induction period is too worm. Induction of flowering in litchi requires an average minimum temperature of approximately 10-14°C for 4-12 weeks, depending on the cultivars. Variation in time of panicle emergence, panicle development, and anthesis among the cultivars in relation to seasonal progressions in temperature affect the fruit set. Experimental evidence suggest that temperature above 15°C increased vegetative growth and reduced or eliminated flowering. However, the temperature above which flowering fails is still not clear, nor is the time that the plants needs to grow at lower temperature for successful flower induction. It has also been suggested that not only is low temperature needed for induction, but also water stress throughout the autumn and winter. Six weeks autumnal water stress was reported to cause a significant increase in flowering of 'Mauritus' and 'Floridian' litchi in Israel. Gibberellins inhibits flowering in litchi and counteracts the flower-inducing influence of low temperature, while treatments such as cincturing, root pruning and application of growth retardants reverse the inhibitory effects of high temperature. It is believed that the conversion of vegetative bud to panicle in litchi is dependent on changes in content of endogenous growth substances. This paper discussed the various factors influencing the flowering in litchi and available technology to overcome.

Effect of thermal induction temperature on re-dispersion behavior of Ni nanoparticles over Ni/SBA-15 for dry reforming of methane

In the previous research, we found that thermal treatment at high temperature could induce the re-dispersion of Ni particles on SBA-15 for dry reforming of methane (DRM). Here, we aimed to study the re-dispersion behavior of Ni particles of Ni/SBA-15 at different temperatures. The results indicated that the mean Ni particle size of Ni/SBA-15 catalysts were 16.9 nm, 14.5 nm, 7.1 nm and 18.4 nm after thermal treatment at 700 °C, 800 °C, 900 °C and 1000 °C, respectively. It could be seen the optimal inducing temperature of Ni/SBA-15 was at 900 °C. The relatively lower inducing temperature did not drive the re-dispersion of Ni particles sufficiently, while the large Ni particles were formed by re-aggregation of re-dispersive Ni species at relatively higher inducing temperature. After 34 h DRM reaction, encapsulated carbon was formed over the catalyst induced by low temperature and the catalytic performance decreased. However, a slight amorphous carbon was discovered over the catalyst induced at 900 °C with highly dispersion. Interestingly, in spite of a large amount of carbon deposition, the 1000Ni/SBA-15 still maintained excellent catalytic activity.

Extracellular Overproduction of Recombinant Iranian HPV-16 E6 Oncoprotein in Lactococcus lactis Using the NICE System

Aim: This study aimed to optimize production of HPV-16 E6 by recombinant Lactococcus lactis. Materials & methods: Optimization procedures were conducted on the factors of nisin amount, induction temperature, cell density at induction time, glucose and yeast extract concentrations. Results: Cell densities reached 5.2 and 1.74 g/l, and maximum rE6 production reached 45.25 and 15.91 μg/ml for optiE6 and E6, respectively, at 75 g/l initial glucose concentration in the batch study. During fed-batch fermentation, protein values were improved by feeding with yeast extract and GM17 medium, reaching the maximum of 80.92 and 15.95 μg/ml, and the maximum biomass reached 9.62 and 3.12 g/l, respectively. Conclusion: These encouraging outcomes represent L. lactis cells as an efficient cell factory for antigen production.

Antioxidation of Rosemary in Polypropylene

Effects of Rosemary Antioxidanton, extracted from Rosmarinus officinalis with different solvents, on the antioxidantive properties of polypropylene were evaluated by measuring the oxidation induction temperature. For comparison purposes, the effects of a synthetic phenolic commercial antioxidant Irganox B215, were also analyzed. The results showed that Rao is a more efficient thermal antioxidant for polymers compared to Irganox B215 in low concentration. Rao can be used as a natural antioxidant in place of synthetic antioxidants for polymers. Rao has the characteristic of being harmless and having high activity, good stability and abundant resources to be a good natural antioxidant.

Process parameters optimization to produce the recombinant protein CFP10 for the diagnosis of tuberculosis

The aim of this study was to evaluate the parameters that affect the production of the recombinant 10 kDa culture filtrate protein (CFP10), a promising reagent of high specificity for intradermoreaction and other antigen-based methods used in the diagnosis of tuberculosis. Conditions of Escherichia coli growth temperature, induction temperature and IPTG-inducer concentration were evaluated in shake flasks and dissolved O2 concentrations of 15 and 30% were evaluated in a bioreactor. The process parameters defined on small scale were: growth temperature between 30 and 37 °C, induction temperature of 26 °C and IPTG concentration of 0.12 mM. The process conducted with 15% dissolved O2 presented a recombinant protein yield of 78.6 mg g−1 biomass and a proportion of recombinant protein (insoluble fraction) in relation to total insoluble protein of 72%, at the time of maximum productivity. The operation with 30% dissolved O2 resulted in lower recombinant protein yields of 62.9 mg g−1 biomass and 20% in relation to total insoluble protein, but in higher overall concentration in the culture broth (69.2 mg L−1versus 48.3 mg L−1). The protein identity was confirmed by mass spectrometry, showing high similarity to CFP10, 10 kDa of Mycobacterium tuberculosis H37Rv (score 95), and the purified antigen presented reactivity by the Western blotting assay.

Effect of sewage sludge composition on the susceptibility to spontaneous combustion.

The different technologies applied to the sewage sludge management have in common a first step devoted to the storage. In the case of dried sludges, this storage leads to important safety concerns because of the explosive character of the resulting dusts. In order to ensure safety in the storage step, it is necessary to evaluate the spontaneous combustion trends on terms of measurable chemical and physical properties of the dried sludges. In order to accomplish this scope, twelve samples from different wastewater treatment plants were characterized, correlating the susceptibility to spontaneous combustion with both the sludge composition and the heating value. Equations traditionally used for coals were used to determine the higher heating value from the chemical composition, finding as main source of error the high oxygen content of the sludge samples. Concerning the thermal susceptibility, different parameters were obtained (Maciejasz Index, induction temperature, maximum weight loss temperature, characteristic temperature and activation energy), being in all cases the spontaneous combustions favored by high H/C and low O/C ratios. Likewise, the presence of sulphur in the dried sludge was found to increase the thermal susceptibility of the material. This effect is tentatively explained with the formation of pyrophoric iron sulfides.

Upgrading biochar from bio-oil distillation residue by adding bituminous coal: Effects of induction conditions on physicochemical properties

In this study, biochar was produced by co-pyrolysis of bio-oil distillation residue and bituminous coal under different induction temperature and gas flow rate in a tube furnace. Central composite design was introduced to explore the combined effects of experimental conditions on biochar. The physicochemical properties of biochar from different induction conditions were comprehensively evaluated by elemental analysis, Fourier transform infrared spectrometry (FTIR) and Raman spectroscopy based on response surface methodology. The results showed that bituminous coal was beneficial to the increase in biochar yield, whereas temperature had the opposite effect and the effect of gas flow rate was not obvious. Moreover, C/O ratio increased with the increase of pyrolysis temperature and bio-oil distillation residue in feedstocks, while C/H ratio increased only with increasing temperature. Gas flow rate had a more pronounced descent effect on C/H compared with C/O. In addition, induction conditions caused a relative weakening of CC stretching vibration and the relative enrichment of CH in biochar. Bituminous coal, temperature and gas flow rate all contributed to the conversion of small aromatic rings of biochar to large aromatic rings during the co-pyrolysis process.

Differential intracellular localization of Hsp70 in the gill and heart tissue of fresh water prawn Macrobrachium malcolmsonii during thermal stress.

Exposure of organisms to heat stress induces the expression of evolutionarily conserved proteins called the stress proteins or heat shock proteins (HSPs). At the cellular level, HSPs by acting as molecular chaperone prevents the heat induced aggregation of denatured proteins and play a significant role in adaptation to temperature. Among different HSP family members, Hsp70 is the highly conserved and ubiquitously expressed protein. The present study is carried out to detect changes in the localization of Hsp70/Hsc70 in gill and heart tissues of control and heat shocked juveniles of Macrobrachium malcolmsonii that could be correlated with the functional significance of these two isoforms. Two groups of prawn acclimated at 30°C were exposed to reported optimum Hsp70 induction temperatures of 36°C and 38°C for heart and gill, respectively, for a duration of 48h. These tissues were processed by immunocytochemical methods to detect intra-cellular localization of Hsp70/Hsc70. Western blotting analysis was performed to determine the cytoplasmic or nuclear localization of Hsp70/Hsc70 and band intensity was detected in total lysate, cytosolic and nuclear extracts of gill and heart tissue. The present investigation clearly shows that there are alterations in the intracellular localization of Hsp70/Hsc70 in the cells of the gill and heart tissues of M. malcolmsonii following heat stress. The western blotting results corroborate the results obtained by immunohistochemical localisation. The differential intracellular localization of Hsp70/Hsc70 appears to indicate the functional roles of this stress protein during exposure to thermal stress.

High-level expression of Aerococcus viridans pyruvate oxidase in Escherichia coli by optimization of vectors and induction conditions.

This study demonstrates that a highly soluble pyruvate oxidase can be obtained in recombinant Escherichia coli by optimizing vectors and induction conditions. The pyruvate oxidase yield achieved is the highest reported so far, which provides a convenient and cost-saving way to produce pyruvate oxidase. This research promotes pyruvate oxidase application in the pharmaceutical and biochemical industries.

Evaluation of temperature induction in focal ischemic thermocoagulation model.

The thermocoagulation model, which consists of focal cerebral ischemia with craniectomy, is helpful in studying permanent ischemic brain lesions and has good reproducibility and low mortality. This study analyzed the best conditions for inducing a focal ischemic lesion by thermocoagulation. We investigated parameters such as temperature and thermal dissipation in the brain tissue during induction and analyzed real-time blood perfusion, histological changes, magnetic resonance imaging (MRI), and motor behavior in a permanent ischemic stroke model. We used three-month-old male Wistar rats, weighing 300–350 g. In the first experiment, the animals were divided into four groups (n = 5 each): one sham surgery group and three ischemic lesion groups having thermocoagulation induction (TCI) temperatures of 200°C, 300°C, and 400°C, respectively, with blood perfusion (basal and 30 min after TCI) and 2,3,5-Triphenyl-tetrazolium chloride (TTC) evaluation at 2 h after TCI. In the second experiment, five groups (n = 5 each) were analyzed by MRI (basal and 24 h after TCI) and behavioral tests (basal and seven days after TCI) with the control group added for the surgical effects. The MRI and TTC analyses revealed that ischemic brain lesions expressively evolved, especially at TCI temperatures of 300°C and 400°C, and significant motor deficits were observed as the animals showed a decrease frequency of movement and an asymmetric pattern. We conclude that a TCI temperature of 400°C causes permanent ischemic stroke and motor deficit.

Quantifying the germination response of spring canola (Brassica napus L.) to temperature

The models based on thermal time concept have been widely applied to quantify the germination responses of seeds to temperature. The majority of these models assume a Normal distribution for both sub-optimal thermal time θT(G) and maximum temperature Tc(G) to describe the variation in time to germination. In this study, the response of germination to temperature in six spring canola (Brassica napus L.) cultivars was described using the thermal time model.Germination tests were carried out at constant temperatures of 8, 12, 16, 20, 24, 28, 32, 33, 34, 35 and 36 °C. The thermal time model accurately described germination patterns of different cultivars in response to temperature over sub- and supra-optimal. The thermal thresholds for seed germination, base temperature (Tb), sub-optimal thermal time needed to achieve 50% germination (θT(50)), maximum germination temperature for induction of 50% thermoinhibition in seeds (Tc(50)) and supra-optimal thermal time to complete germination (θTc) differed significantly among the canola cultivars studied. The values of Tb, θT(50), Tc(50) and θTc ranged from 4.86 to 7.10 °C, 358.89–407.19 °C h, 33.90–34.42 °C and 27.66–38.26 °C h, respectively. Within each cultivar optimum temperature (To(G)) showed little variation amongst different germination percentiles. The magnitude of To(50) ranged from 31.86 to 32.25 °C depending on the cultivar. The thermal thresholds for seed germination identified here explained the differences in seed germination found among cultivars. All model parameters may be readily used in crop simulation models.

β-alanine production using whole-cell biocatalysts in recombinant Escherichia coli

In this study, we aimed at developing an efficient whole-cell biocatalytic process for bio-production of β-alanine (3-AP) from l-aspartate. To obtain the highly efficient whole-cell biocatalysts, l-aspartate-α-decarboxylase (ADC) from different donor organisms, including Escherichia coli, Corynebacterium glutamicum, and Bacillus subtilis were selected and systematically analyzed for their activities in E. coli. Among theses, E. coli BL21(DE3)/pET28a-panDC.g showed the highest activity. The effects of induction temperature, incubation time, reaction temperature, reaction pH, metal ion additives and substrate concentration were subsequently evaluated to improve the whole-cell biocatalytic efficiency. The maximum 3-AP production could reach 24.8 g/L with a yield of 92.6% under the following optimal conditions: 37 °C, pH 6.0, 50 mM Fe2+, 40 g/L l-aspartate and reaction for 20 h. Taken together, this work established an efficient biotransformation process for the production of 3-AP using the whole E. coli expressing ADC from C. glutamicum.

Efficient gamma-aminobutyric acid bioconversion by engineered Escherichia coli

ABSTRACTGamma-aminobutyric acid (GABA) can be converted into 2-pyrrolidone, an intermediate in the synthesis of nylon 4 and agrochemicals, which has great potential for application in the chemical industry. The main aim of this work was to construct a simple and efficient process for industrial production of GABA from L-glutamic acid (L-Glu) by whole-cell bioconversion. The gene encoding glutamate decarboxylase (GAD) from Lactococcus lactis FJNUGA01 was overexpressed using the most available vector in Escherichia coli, pET-28a. GABA production was enhanced by optimizing the concentration of the catalyst isopropyl-β-D-thiogalactoside (IPTG), induction temperature and induction time. After optimization, GABA production reached 98.4 g L−1 with 96 mol% conversion within 6 h was achieved by whole-cell conversion using the cells induced with 1 mmol L−1 IPTG for 12 h at 30 °C. Furthermore, when the initial concentration of L-Glu was adjusted, 204.12 g L−1 GABA with 34 g L−1 h−1 productivity was reached using 2 mol L−1 L-Glu as the substrate. During the 6 h whole-cell bioconversion process, almost all L-Glu was converted to GABA with a conversion efficiency of ∼99%. The high conversion efficiency and high productivity made the GABA purification occur downstream, and the whole process is more simple and economical for industrial application.

High cell‐density cultivation of phenolic acid decarboxylase‐expressing Escherichia coli and 4‐vinylguaiacol bioproduction from ferulic acid by whole‐cell catalysis

AbstractBACKGROUND4‐vinyl guaiacol (4‐VG) is a high value‐added product widely used in the cosmetic, pharmaceutical, and chemical industries. The practical bioproduction of 4‐VG using phenolic acid decarboxylases has been limited by its relatively high biocatalyst cost and low yield and product concentration.RESULTSIn the present study, high‐cell density cultivation was employed to improve the activity and production of phenolic acid decarboxylase from Bacillus licheniformis (BLPAD) in recombinant Escherichia coli. The factors influencing enzyme production in E. coli such as the induction point and temperature for induction and feeding strategies were optimized. The highest BLPAD activity (531 U mL‐1) and productivity (20.4 U mL‐1 h‐1), respectively, were achieved in a 5 L bioreactor using a glucose exponential feeding strategy with isopropyl β‐D‐thiogalactoside (IPTG) as inducer. Furthermore, a high BLPAD production level (512 U mL‐1) was achieved using lactose as an inducer and continuous lactose feeding. Using a biphasic emulsion system with equal volumes (1 L) of cyclohexane as a organic solvent and a substrate fed‐batch strategy, the concentration and conversion yield of 4‐VG reached 129.9 g L‐1 (85.6%) in a 5 L bioreactor by whole‐cell biocatalysis, which is the highest reported to date.CONCLUSIONThis study describes a strategy for large‐scale 4‐VG bioproduction using the biocatalytic method. © 2018 Society of Chemical Industry

Improvement on Extracellular Production of Recombinant Burkholderia cepacia Lu10-1 Lipase by Escherichia coli

The purpose of this study was to investigate several strategies on enhancing extracellular production of recombinant lipase from Burkholderia cepacia Lu10-1 in recombinant Escherichia coli BL21(DE3). In the present study, a fed-batch fermentation strategy for the excellular production of lipase by E. coli has been established. First of all, different induction methods (including selection of inducers, inducer concentration, induction temperature and induction time) were investigated and the results indicated that these factors played an important role in lipase production. When induced by 0.8 g L-1 h-1 lactose at 30°C and at a OD600 of 30, the lipase activity in the culture medium could achieve 58 U mL-1. Moreover, addition of glycine and calcium ions can increase the extracellular yield of lipase. With supplementation of the culture with 0.5% (w/v) glycine and 2.5 mM Ca2+, the maximum extracellular activity of lipase could reach 85 U mL-1, which was 2.1 fold higher than that of the control. This study might provide fermentation strategy for the extracellular production of other heterogonous proteins expressed in E. coli.

Enhanced a novel β-agarase production in recombinant Escherichia coli BL21 (DE3) through induction mode optimization and glycerol feeding strategy

Agarases are hydrolytic enzymes that act on the hydrolysis of agar and have a broad range of applications in food, cosmetics and pharmaceutical industries. In this study, a glycerol feeding strategy based on induction mode optimization for high cell density and β-agarase production was established, which could effectively control acetate yield. First, exponential feeding strategy of glycerol with different overall specific growth rates (μ) was applied in the pre-induction phase. The results showed that the low μ (μ=0.2) was suggested to be the optimal for cell growth and β-agarase production. Second, the effects of induction temperature and the inducer concentration on cell growth and β-agarase production were investigated in the post-induction phase. When induced by isopropyl-β-d-thiogalactoside (IPTG), the strategy of 0.8 mmol/L IPTG induction at 20°C was found to be optimal for β-agarase production. When cultivation was induced by continuous lactose feeding strategy of 1.0 g/(L·h), the β-agarase activity reached 112.5 U/mL, which represented the highest β-agarase production to date. Furthermore, the β-agarase was capable of degrading G. lemaneiformis powder directly to produce neoagarooligosaccharide, and the hydrolysates were neoagarotetraose (NA4) and neoagarohexaose (NA6). The overall research may be useful for the industrial production and application of β-agarase.

Expression and Characterization of Recombinant Sucrose Phosphorylase.

SPase is widely used in the food, cosmetics, and pharmaceutical industries. Previously, a SPase gene was cloned from Bifidobacterium longum JCM1217 and constructed into Escherichia coli BL21. In this paper, its expression conditions were optimized. The results showed that several induction factors determined the expression efficiency of SPase. The initial cell density, IPTG concentration, and induction time and temperature significantly (p < 0.01) affected the total protein content and activity of expressed SPase. The highest expression efficiency was obtained at an initial cell density of OD600 = 0.5, with 0.05mM IPTG, followed by shaking at 180rpm and incubation at 30°C for 15h. The purified SPase had a specific activity of 122.1 U/mg, which was raised by 1.85 -fold more than that before optimization, and its recovery yield was 86%. Furthermore, SPase also showed higher thermostability. The results of this study provide essential information for the industrial production of SPase.

Optimization of the expression of levansucrase L17 in recombinant E. coli

ABSTRACTLevansucrases synthesize levans and fructooligosaccharides, which are of interest in the food and pharmaceutical industry. Leuconostoc mesenteroides Lm 17 produces levansucrase of about 120 kDa. The encoding gene from this strain was cloned and expressed in Escherichia coli BL21(DE3). The cloned gene encodes a 1022 amino acids long levansucrase with 96% identity to levansucrase LevS from L. mesenteroides NRRL B-512F strain. The induction and expression of the levansucrase gene were performed at temperatures between 15 °C and 37 °C, and concentration of the inducer isopropyl-β-D-thiogalactopyranoside from 0.1 to 2.0 (mmol/L)-1. We report for the first time recombinant expression of a levansucrase gene at a low temperature of induction, after cell biomass accumulation at 37 °C. The highest enzyme activity of 1.90 (U/mg)-1 was measured in TB medium at 18 °C temperature of induction, and concentration of the inducer from 0.1 to 1.0 (mmol/L)-1. The in situ analysis of the purified enzyme showed an active band of about 120 kDa, similar to the one produced by the native strain. The purified enzyme has a temperature optimum at 35 °C, pH optimum at 5.5, and Km = 64 (mmol/L)-1 of sucrose.