Induction Period Time Research Articles

Characterization of accelerated hydrolysis degradation of poly (lactic acid) in phosphate buffered saline solution

For the reliable use of polylactic acid (PLA) materials in the human body for supportive implants, an appropriate accelerated testing method to assess the lifetime of the PLA with an acceptable model that can describe the entire degradation process is required. In this study, accelerated degradation were conducted on the polylactic acid (PLA) exposed to the phosphate buffered saline (PBS) solution at elevated temperatures, 50 ℃, 60 ℃, and 70 ℃. The high level of accelerated degradation was achieved with elevating temperatures. The evolution of surface degradation degree with exposure time was quantified by measuring the molecular end group and modeled by a proper equation. In addition, it was demonstrated that hydrolysis-induced chain-scission is the governing mechanism in the accelerated degradation. The chemi-crystallization behavior with the hydrolysis degradation was also characterized. The morphological observation revealed that the microcracks and pits are pronouncing mechanisms of surface damage. The tensile properties were severely degraded after a certain period of induction time, depending on the temperature. The sorption kinetics were also assessed and explained during the entire lifetime until the severe mass loss, based on the diffusion with degradation behavior, as well as the evolution of the morphological damages. The formation of the surface degradation layer and subsequent damages are suspected to result in early saturation and secondary sorption behavior at the elevated temperature. Finally, the integrated correlations between the sorption behavior, amount of hydrolysis degradation, and mechanical property decrease were physically described, and accurate correspondences were obtained.

P509 Upadacitinib improves symptomatic responses in patients with moderately to severely active Crohn’s disease

Abstract Background Upadacitinib (UPA), an oral Janus kinase inhibitor approved for the treatment of moderately to severely active Crohn’s disease (CD), has demonstrated the ability to provide rapid symptom relief within the first week of induction treatment in patients with CD.1 As symptomatic remission is critical for patients, this phase 3 post hoc analysis evaluated the impact of UPA on patient-reported outcomes (PROs) of abdominal pain score (APS) and stool frequency (SF) over the full induction and maintenance time periods. Methods Data were pooled from the U-EXCEL (NCT03345849) and U-EXCEED (NCT03345836) induction studies evaluating patients with moderately to severely active CD with an average daily APS ≥ 2 and/or SF ≥ 4 and received UPA 45 mg (UPA45) once daily (QD) or PBO for 12 weeks. Patients who achieved clinical response to 12 weeks of UPA45 induction were re-randomised in a maintenance study (U-ENDURE, NCT03345823) to receive UPA 15 mg (UPA15) QD, UPA 30 mg (UPA30) QD, or PBO for 52 weeks. APS and SF were recorded in a daily diary and evaluated over time. Results The average daily APS (mean: PBO 1.9, UPA45 1.9) and SF (mean: PBO 5.6, UPA45 5.4), were similar between the treatment groups at induction baseline (BL). Of patients reporting BL APS ≥ 1 (PBO 91.6%, UPA45 92.4%) or BL SF ≥ 2.8 (PBO 85.6%, UPA45 85.2%), higher proportions of patients receiving UPA vs PBO achieved APS = 0 or SF ≤ 1, or complete resolution of symptoms (APS = 0 and SF ≤ 1) at week 12 of induction, as well as at week 52 of maintenance (all P ≤ .001; Figure 1A). During induction, the mean change from BL in APS and SF was improved with UPA45 vs PBO starting at week 2 through to week 12 (all P < .001; Figure 1B-C). Throughout the 52-week maintenance period, a higher proportion of patients receiving UPA15 or UPA30 achieved APS ≤ 1 or SF ≤2.8 vs PBO (Figure 1B-C). Patients treated with UPA30 demonstrated a numerically higher rate of symptomatic response vs UPA15. In patients who met the Crohn's Disease Activity Index (CDAI) criteria per US labeling (CDAI ≥ 220 at induction BL; clinical response [CR-100] at week 12 with UPA45),2 comparable symptom improvements were observed over time compared to the overall study population. Conclusion Patients with moderately to severely active CD demonstrated improvements in APS and SF as early as 2 weeks after UPA induction treatment. A greater proportion of patients achieved PRO-defined remission within 12 weeks of UPA induction treatment compared with PBO, which were sustained through week 52 of UPA maintenance treatment.

Investigation of Phytoestrogens Found in Sesame Seeds via Computational and Translational Approaches

Polycystic Ovarian Syndrome (PCOS) is a common endocrine disorder that primarily impacts reproductive-aged women. Phytoestrogens, also known as plant oestrogens, are naturally occurring compounds with a chemical structure similar to that of human oestrogen. In this study, rational and translational approaches were used to check the efficacy of phytoestrogens found in sesame seeds. The objectives included the prediction and comparison of proteins responsible for PCOS, that is, MADH4 and phytoestrogens (ascorbic acid and thiamine) present in sesame seeds. Moreover, their interaction and inhibition of the target protein through molecular docking as a rational layout were recorded. The effects of these phytochemicals were further confirmed by using PCOS induced Sprague dawley rats with standard drug Clomiphene citrate. In the translational study, PCOS was induced in an animal model and ovulation and estrous cycles were observed. Afterwards, the effects of the crude extract of sesame seed were further confirmed by measuring the levels of progesterone, testosterone, and estrogen serum levels in control, positive control, and all the sesame seed and standard drug treated groups. Two lead compounds namely ascorbic acid and thiamine obtained from sesame seeds showed the best results as compared to the standard drug Clomiphene citrate which imparts immunotoxicity against MADH4 protein responsible for the onset of PCOS. Furthermore, different stages of ovulation namely proestrus, metestrus, estrus, and diestrus were observed with vaginal smears obtained in the disease induction time period. The results obtained from the hormonal profile of all the groups indicated that the progesterone, estrogen, and testosterone levels were statistically significant with p-values less than 0.05. The findings indicated that sesame seeds possess the capability to suppress the expression of MADH4, while also maintaining the regulated hormone levels.

Experimental and modelling approach to investigate the mechanisms of formation damage due to calcium carbonate precipitation in carbonate reservoirs

Calcium carbonate (CaCO3) precipitation, due to incompatibility between the injected water (IW) and formation water (FW), is known to be a major operational obstacle during water flooding projects. In this study, initially by using OLI Scale Chem and ScaleSoftPitzer software and static beaker tests, the potentiality of CaCO3 scaling was determined from the given ionic content of incompatible synthetic brines, under different conditions (temperature, pressure, and volume mixing ratio of incompatible brines). The results showed that the maximum amount of CaCO3 salt was formed at a volume mixing ratio of 0.8:0.2 (IW:FW). The simulation results showed that OLI software is more reliable than the ScaleSoftPitzer. In the second stage of this work, the 0.8:0.2 proportion of IW:FW was selected to examine the mechanisms under which the maximum formation damage of the tight carbonate cores occurred through the water injection experiments. In addition, the turbidity of the bulk solution was measured to confirm the core flooding outcomes. Various hydrodynamic parameters (low flow rate, scaling tendency, and the temperature) were evaluated in these experiments. Bulk induction time (tind) and scaling period (ts) were determined from the setup. Either heterogeneous nucleation (i.e. crystallization processes), or both heterogeneous nucleation and adhesion of pre-deposited crystals from the mixed incompatible brines to the pore wall of the cores, were attributed as the principal mechanisms of the formation damage of tight carbonate rocks owing to CaCO3 salt formation. Moreover, a semi-empirical model was established from this laboratory study, which predicts the scaling period (ts) as a function of interfacial energy, temperature, and scaling tendencies.

The auto-ignition behaviors of HMX/NC/NG stimulated by heating in a rapid compression machine

In this work, we have for the first time, applied a rapid compression machine (RCM) to generate initial uniformly high temperature environment to investigate the auto-ignition behaviors of solid energetic material (HMX/NC/NG). Pressure evolution recording and high speed visualization were synchronized to reveal the response of energetic material to thermal stimulus in a time scale of the order of 100 ms. Results show that at sufficiently high end of compression (EOC) pressure and temperature, auto-ignition of solid energetic material is observed after certain period of induction time upon EOC. The ignition delay time defined by the first flame spot observation from high speed imaging (IDTI) is smaller than defined by the maximum pressure rise rate instant (IDTP). However, both IDTI and IDTP decrease with the increase of EOC pressure and temperature. In addition, the burning duration also decreases, indicating a faster burning rate. By tuning the EOC pressure and temperature, the critical thermodynamic condition that separates the auto-ignition region and the non-ignition regime is obtained. The present method of thermal stimulus generation is believed to provide a new approach for evaluating the thermal stability of energetic materials, beyond the literature on cook-off test approaches.

Evaluation of the efficacy of potential anesthetic agents on cuttlefish (Sepia pharaonis) juveniles

Anesthesia is often used to relieve stress and reduce mortality rates in aquaculture systems. Here, we assessed the efficacy of four anesthetic agents on cuttlefish (Sepia pharaonis) juveniles. Concentration-response trials were performed to evaluate the induction time and recovery period after short-term anesthesia. MS-222 (5−100 mg L−1) was unable to induce anesthesia in cuttlefish juveniles. Treatment of the cuttlefish with 0.2−3 ml L−1clove oil induced death. By contrast, the anesthetization of cuttlefish with magnesium chloride solution (0.0125−0.2 mol L−1) and ethanol (2.5−30 mL L−1) was successful and the cuttlefish recovered well. Analysis of water quality index during simulated transportation revealed that 0.0125 mol L−1magnesium chloride solution was effective for cuttlefish transport for at least 12 h. 1H NMR spectroscopy coupled with multivariate data analysis and univariate data analysis were performed to reveal the metabolites in the cuttlefish central nervous system influenced by MgCl2. A total of 23 metabolites including amino acids, carboxylic acids, choline, betaine, nucleosides and nucleotides were identified. Levels of isoleucine, leucine, valine, tyrosine and glutamate were altered following anesthetization. Magnesium chloride indirectly increased the content of the inhibitory neurotransmitter glycine. It also reduced the content of excitatory neurotransmitter Dopamine by increasing the content of tyrosine thereby achieving anesthetization.

Optimization of Parameters for Expression and Purification of G Glycoprotein Ectodomain of Respiratory Syncytial Virus

Aim: G glycoprotein ectodomain (Ge) of BA genotype of group B respiratory syncytial virus was expressed and purified to achieve maximum yield of the protein. Materials & methods: We optimized different parameters like strains, temperature, inducer concentration and post induction time period for efficient protein expression in Escherichia coli. The protein was purified using affinity chromatography and confirmed by western blotting. Results: It was concluded that a 5-h induction with 0.75 mM isopropyl β-D-1-thiogalactopyranoside at 37°C in BL21(DE3) cells was the most favorable condition for maximal protein expression. The far-UV circular dichroism spectroscopy suggested that it is an α-helical protein. Conclusion: The purified Ge protein can be characterized by antigenic and biophysical methods in future studies, which will probably assist in vaccine development.

Dopaminergic D1 receptors in the nucleus basalis modulate recovery from propofol anesthesia in rats.

Objective(s):Melatonin, an important hormone secreted by the epiphysis, is a powerful anti-oxidant with a high potential to neutralize medical toxins. The goal of this study was to demonstrate the beneficial effect of melatonin on epididymal sperm and reproductive parameters in mice treated with acetylsalicylic acid (ASA).Materials and Methods:Thirty-nine SD rats were randomly split into D1 receptor agonist (chloro-APB), D1 receptor antagonist (SCH23390), and saline groups after preparing NB microinjection model. We observed the effect of NB microinjection of SCH23390, chloro-APB, or saline on the period of induction and recovery time of propofol anesthesia and recorded the changes of electroencephalogram (EEG) simultaneously.Results:NB microinjection of chloro-APB accelerated the recovery from propofol anesthesia (P<0.05), without affecting the induction of anesthesia (P>0.05); NB microinjection of SCH23390 produced the opposite effects. NB microinjection of saline did not influence the induction or recovery of propofol anesthesia (P>0.05). NB injection of chloro-APB decreased the ratio of δ power and increasedαand β ratios in prefrontal cortex EEG (P<0.05); NB microinjection of SCH23390 increased δ ratio and decreased β ratio (P<0.05); NB microinjection of saline had no significant effect on EEG (P>0.05)Conclusion:D1 dopamine receptors in NB are involved in modulating the emergence from propofol anesthesia, but not affecting the induction of propofol anesthesia.

Methodology in Wistar rats periodontitis induction: A modified ligation technique with injection of bacteria

Introduction: Periodontitis is an inflammation affecting the supporting tissue of the teeth. It is characterized by periodontal ligament destruction and progressive alveolar bone loss. Periodontitis is often induced in laboratory animal models, such as Wistar rats used for experimental models. This study was conducted to develop a reproducible technique for induction of periodontitis in the mandible of Wistar rats using a modified ligation technique with an additional injection of Aggregatibacter actinomycetemcomitans. Context: Periodontitis is an inflammation affecting the supporting tissue of the teeth. It is characterized by periodontal ligament destruction and progressive alveolar bone loss. Aims: The aim of this study was to develop a reproducible technique for induction of periodontitis in the mandible of Wistar rats using a modified ligation technique with an additional injection of A. actinomycetemcomitans. Settings and Design: The study was conducted at LPPT Unit IV Universitas Gadjah Mada, Yogyakarta. Subjects and Methods: Ten 2-month-old male adult Wistar rats were used as experimental subjects with an average weight of 150–200 g. Nonresorbable silk ligature wire (4/0) was used as ligatures and placed with an “8”-shaped knot technique. The ligatures were placed in between both central incisors of the mandible for 7 days with additional injections of A. actinomycetemcomitans on the 1st day. The procedure was performed under ketamine anesthesia. After 7 days, ligatures were removed and the animal subjects were euthanized with cervical dislocation method and samples of mandibles were preserved in formalin solution and processed histologically and radiographically. Results: Modified induction technique of periodontitis with ligatures and additional injection of A. actinomycetemcomitans showed significant clinical inflammation, periodontal ligament widening, attachment loss, and alveolar bone loss. Conclusions: We demonstrated clinical, radiographic, and histological evaluation from this modified induction technique and concluded that it has several advantages: shorter period of induction time with more significant clinical changes and advanced bone loss, simplifying the technique for induction of periodontitis.

Induction of Labor Versus Expectant Management in Patients With Non-anomalous Idiopathic Polyhydramnios [16E

INTRODUCTION: Polyhydramnios is associated with increased risk of stillbirth at term, but is historically associated with higher risk of cesarean section. The objective was to determine if induction of labor at 38-39 weeks gestation reduces the risk of cesarean compared to expectant management for women with polyhydramnios at term. METHODS: This was a single center, retrospective cohort study of singleton, vertex patients with a diagnosis of polyhydramnios at 38 weeks gestation between July 2014 and March 2018. IRB approval obtained. Women with planned induction at 38 0/7 to 39 6/7 weeks were compared to those expectantly managed. Patients with placental or uterine pathology, significant fetal anomaly, and women undergoing an induction of labor for a medical indication (e.g. diabetes, chronic hypertension) were excluded. Induction time period spanned from 38 0/7 to 39 6/7 weeks. The primary outcome was cesarean section. RESULTS: 168 singleton non-anomalous idiopathic polyhydramnios pregnancies met the inclusion criteria. 97 were induced and 71 were expectantly managed. Cesarean delivery was reduced for women induced compared to those expectantly managed (18.8% vs 35.7%, p=0.015). There were no differences in maternal or neonatal secondary outcomes. There was one case of cord prolapse and one cesarean hysterectomy in the induction group. One case of stillbirth was diagnosed in the expectant group which placental pathology revealed multiple chorangiomas and cardiomegaly on fetopsy. CONCLUSION: Induction of labor is associated with reduced risk of cesarean section in non-anomalous polyhydramnios compared to expectant management. Given the increased risk of stillbirth, induction is preferred over expectant management.

Generation and characterization of a zebrafish muscle specific inducible Cre line.

Zebrafish transgenic lines provide valuable insights into gene functions, cell lineages and cell behaviors during development. Spatiotemporal control over transgene expression is a critical need in many experimental approaches, with applications in loss- and gain-of-function expression, ectopic expression and lineage tracing experiments. The Cre/loxP recombination system is a powerful tool to provide this control and the demand for validated Cre and loxP zebrafish transgenics is high. One of the major challenges to widespread application of Cre/loxP technology in zebrafish is comparatively small numbers of established tissue-specific Cre or CreERT2 lines. We used Tol2-mediated transgenesis to generate Tg(CrymCherry;-1.9mylz2:CreERT2) which provides an inducible CreERT2 source driven by muscle-specific mylz2 promoter. The transgenic specifically labels the trunk and tail skeletal muscles. We assessed the temporal responsiveness of the transgenic by screening with a validated loxP reporter transgenic ubi:Switch. Further, we evaluated the recombination efficiency in the transgenic with varying concentrations of 4-OHT, for different induction time periods and at different stages of embryogenesis and observed that higher recombination efficiency is achieved when embryos are induced with 10μM 4-OHT from 10-somites or 24 hpf till 48 or 72 hpf. The transgenic is an addition to currently available zebrafish transgenesis toolbox and a significant tool to advance muscle biology studies in zebrafish.

Whole-cell fluorescent bacterial bioreporter for arsenic detection in water

Microbial whole-cell bioreporters have been developed for environmental monitoring of arsenic contamination. Despite the great interest in bacterial bioreporters for arsenite detection, relatively few studies reported their response to arsenate levels. In this study, green fluorescent protein-based whole-cell Escherichia coli bioreporter was constructed for the measurement of both bioavailable arsenite and arsenate in water. The developed bacterial bioreporter has much higher sensitivity toward arsenate in inorganic phosphate-limiting medium compared to minimal medium. Both arsenite and arsenate were detected at 10 µg/l within 2-h induction time period. Furthermore, the bioreporter was able to detect and estimate arsenic levels in groundwater sample. The results demonstrate that the constructed bacterial arsenic bioreporter is applicable in determining the concentrations of the most abundant two ionic forms of arsenic as opposed to analytical methods which gives total content of arsenic. Thus, a comparison of bioavailability of arsenic and its form with its total content would give an insight about the risk of toxicity and also planning of removal processes.

Thermomechanical Concepts and Modeling for Stability Physics in Liquid-Propellant Rocket Engines

Thermomechanical concepts and modeling are used to describe the response of inert and reactive gases to transient, spatially resolved thermal energy deposition. The ultimate goal is to establish the cause–effect relationship between combustion-generated energy deposition and the mechanical disturbances responsible for operationally observed pressure oscillations in liquid-propellant rocket engine combustion chambers as well as to identify physical processes that convert thermal energy to kinetic energy. Asymptotic formulations of the nondimensional describing transient conservation equations for both inert and reactive gases are used to identify nondimensional parameters that characterize fundamental physics occurring as the gas responds to localized heating. The characteristics of the responses depend upon the magnitudes of the suite of parameters. Some are described by hyperbolic partial differential equations; others involve either nearly constant density or nearly isobaric phenomena. Thermomechanical concepts are used to explain how initially imposed small pressure, density, temperature, and velocity disturbances can be the sources of a thermal response that evolves to relatively larger thermomechanical disturbances. The competition between localized, spatially distributed chemical energy addition from a high-activation-energy, one-step, Arrhenius reaction and compressibility effects associated with localized gas compression/expansion is the driver for diverse outcomes. Sufficiently robust thermal energy addition can cause a thermal explosion after an induction time period, followed by relatively large changes in the thermodynamic variables and induced velocity (instability) on a time scale exponentially short compared to that of the induction time.

Heterogeneous crystallization of calcium hydrogen phosphate anhydrous (monetite)

The crystal growth of monetite (CaHPO4, DCPA), the least stable calcium phosphate has been investigated by the seeded growth method from solutions supersaturated exclusively with respect to this phase alone. The kinetics of crystal growth was measured at constant supersaturation at 37°C, pH 6.0. The measurements of the rates of crystal growth of DCPA showed a second order dependence on the relative supersaturation of the solutions with respect to DCPA, suggesting that the rate determining step is surface diffusion of the growth units to the active growth sites of the crystals. The heterogeneous crystallization of brushite (CaHPO4·2H2O, DCPD) on DCPA seed crystals in solutions supersaturated with respect to both DCPD and DCPA showed that DCPD nucleation and growth took place selectively by heterogeneous nucleation on the DCPA seed crystals. The same parabolic dependence of the rates on the relative supersaturation of the solutions with respect to DCPD was found, showing that the mechanism was the same as in the case of growth of DCPA on DCPA seed crystals. Seeding of solutions supersaturated with respect to both DCPA and DCPD at pH 6.0, 37°C with collagen type II in powdered form, resulted to the formation of an apatitic solid. The morphology of the crystals formed on the collagenous matrix suggested that the identified mineral was probably the result of rapid hydrolysis of metastable calcium phosphatephases. The formation of the mineral phase on collagen took place past long induction time periods inversely proportional to the relative supersaturation with respect to DCPD and showed that the collagen substrate did not stabilize calcium phosphate at the same conditions at which DCPA did.

Photocatalytic reductive degradation of polybrominated diphenyl ethers on CuO/TiO2 nanocomposites: A mechanism based on the switching of photocatalytic reduction potential being controlled by the valence state of copper

Highly active CuO-modified TiO2 (Degussa P25) photocatalysts were prepared by an impregnation method. Efficient and rapid degradation of polybrominated diphenyl ethers were achieved on CuO/TiO2 photocatalysts. Both TiO2 and CuO/TiO2 yielded a rapid photocatalytic reduction of decabromodiphenyl (BDE209). However, the photo-reductive degradation of 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) was impossible on TiO2, but became fast on CuO/TiO2. Moreover, the photo-reductive degradation of BDE47 on CuO/TiO2 needed a short induction time period (20s) to initiate the reduction. A mechanism was proposed for the enhanced photo-reductive degradation of BDE47 on CuO/TiO2. During the induction time period, the CuO clusters trapped electrons from TiO2 to form Cu2O as confirmed by XPS analysis. Further surface photovoltage and phase spectroscopic analysis and flatband potential measurements were conducted for TiO2, CuO/TiO2 and Cu2O/TiO2. In the new mechanism, a “switching reduction potential by the valence state of copper” concept was proposed. Because of the higher reduction potential of Cu2O than CuO and TiO2, the in-situ composition change led to a Fermi level shift to a more reductive energy for injecting electrons to BDE47, resulting in the initiation of the photocatalytic reduction of BDE47 on CuO/TiO2. The proposed concept was useful to design and regulate photocatalysts for reductively degrading persistent pollutants.

New Experimental Insights into the Bromate – 4-Aminophenol Photochemical Oscillations

Abstract In this research, it was found that following the photo-dissolution of the intermediate product N-bromo-1,4-benzoquinone-4-imine in the bromate – 4-aminophenol reaction, removal of illumination may allow the system to exhibit spontaneous chemical oscillations. This new observation complements the earlier report that the bromate – 4-aminophenol reaction could only oscillate under continuous illumination. Our exploration illustrates that the initial concentrations of bromate, 4-aminophenol and sulfuric acid have great influence on whether or not the system requires constant illumination for exhibiting oscillatory behavior. There is indeed an optimal illumination time interval at which the subsequently un-illuminated system would exhibit a large number of high frequency oscillations with or without an induction time period. Similar influences were also observed in the presence of cerium, in which the system exhibited sequential oscillations. Being able to respond to light in both a negative and constructive way makes this oscillatory system an attractive model for investigating perturbed nonlinear reaction dynamics.

Effect of Surfactants on the Oscillatory Behaviour of Metal-ion Catalyzed Pyrogallol based Belousov-Zhabotinsky Reaction

The present investigation pertains to the effect of surfactants on the oscillatory behavior of the catalyzed Belousov-Zhabotinsky (BZ) reaction having pyrogallol as organic substrate in a continuous stirred tank reactor (CSTR) at 30±0.1 oC. The surfactants used in this study are sodium dodecyl sulphate (SDS) as the anionic surfactant, cetyl trimethylammonium bromide (CTAB) as the cationic surfactant and triton x-100 (TX-100) as the neutral surfactant. The results revealed that the addition of the surfactants above their critical micelle concentration (cmc) influenced the oscillatory parameters with induction period showing a definite variation with the increasing concentration of aforesaid surfactants. It is noteworthy to mention that the ability of micelles to selectively compartmentalize ions and molecules may account for their effects on the induction period, amplitude and time period of the BZ system under investigation.

Fire Risk Assessment of Spruce Pellets

In the presented paper is assessed fire risk of pellets made from spruce wood (Picea abiesL.) without bark, processed by hot pressing without the use of additional chemicals. Fire risk was assessed on the basis of heat release rate (HRR), the specific carbon monoxide production rate (SCPR) and the time dependence of the induction period of spontaneous ignition on temperature. HRR and SPCR were determined on the cone calorimeter test performed according to ISO 5660-1:2002 standard. Samples were loaded by 20 kW/m2heat flux during the test. The maximum HRR was 229 kW/m2and average HRR was 55 kW/m2. Maximum SCPR was 0.37 g/(m2s) and the average SCPR was 0.16 g/(m2s). The dependence of the induction period of spontaneous ignition on temperature was determined by a modified test performed according to ISO 871:2006 standard. Modification of the test procedure was based on measurement of the induction time period of the spontaneous ignition on temperature, and temperatures higher of 20, 40, 60, 80 and 100 °C than spontaneous ignition temperature. The obtained data proved an exponential dependence of the induction period of spontaneous ignition on temperature.

Unusual observation of fast photodarkening and slow photobleaching in a-GeSe2 thin film

We report an unusual observation of fast photodarkening and slow photobleaching in a-GeSe2 thin film, when subjected to 532nm band gap light illumination. Photobleaching is observed only after complete saturation of photodarkening. A detailed kinetic analysis of photoinduced transmission change reveals that photodarkening is one order faster in comparison to photobleaching. Interestingly, photobleaching has an induction time period and irreversible in nature whereas photodarkening appears to be an instantaneous process with light illumination showing transient characteristics.

Effect of Initial Substrate Concentrations and Temperature on the Oscillatory Behavior of Phloroglucinol-Based Belousov–Zhabotinsky Reaction

Abstract The present study introduces the use of phloroglucinol (1,3,5-trihydroxybenzene) as organic substrate in BZ reaction for the first time. This work has been carried out to assess the influence of initial reagent concentrations on the behavior of phloroglucinol–bromate–ferroin-based BZ reaction in a stirred batch reactor. The oscillations are followed by observing the change in redox potential. Different oscillatory parameters like induction time (tin), time period (tp), amplitude (A), frequency (v), and number of oscillations (N) show different changes with respect to changes in the initial concentrations of organic substrate, bromate and sulfuric acid, and these observations have been explained on the basis of FKN mechanism. The behavior of the aforesaid system in different aqueous acid media has been reported and it is found that sulfuric acid is the best medium for studying the system as it shows a wide oscillatory window compared to that of nitric acid. In phosphoric and perchloric acids the system does not show any oscillatory behavior. Activation parameters of the reaction have been derived by studying the reaction over a temperature range of 15 to 40 ± 0.1 °C. The effect of different catalysts on the oscillatory behavior has been studied and it is found that the system gives good oscillatory behavior with ferroin and Ce(III) whereas a poor response is seen when Mn(II) and Ce(IV) are used as catalysts.