Maximum Retention Time Research Articles

Biosurfactant production by Bacillus amyloliquefaciens, characterization and its potential applications

Aim: To identify indigenous bacteria responsible for producing biosurfactants in soil contaminated by oil and to investigate their potential uses in the fields of pharmaceuticals and environmental applications. Methodology: The microorganisms of oil-contaminated soil were isolated, screened, and identified using 16S rRNA gene sequencing. Bacillus amyloliquefaciens was utilized to produce biosurfactants, and were characterized by UV, TLC, FTIR, HPTLC, and GCMS analysis. Antibacterial activity, plant growth promotion, biocompatibility, and wound healing activity of surfactant were performed. Results: Six bacterial cultures (B1 to B6) were isolated from the soil samples collected from various locations in Kerala and Tamil Nadu. Among the isolates screened for biosurfactant production, Bacillus amyloliquefaciens exhibited the highest capacity for biosurfactant production, confirmed through 16S rRNA gene sequencing. The biosurfactant produced was identified as surfactin of lipopeptide nature, characterized by various analytical techniques: UV absorption at 400 nm, TLC and HPTLC (Rf value of 0.58), FTIR (prominent peak at 3819 cm-1 corresponding to -OH groups), GCMS with a maximum retention time of 12.03. Surfactin effectively inhibited pathogenic bacteria, enhanced plant growth, was biocompatible, and enhanced the rate of cell migration towards wound scratch. Interpretation: The current study revealed that Bacillus amyloliquefaciens, isolated from oil-contaminated soil, is capable of producing biosurfactant surfactin. Additionally, it unveiled a broad spectrum of applications for surfactin, encompassing wound healing, biocompatibility, antimicrobial activity, and promotion of plant growth. Key words: Antibacterial activity, Biocompatibility, Bacillus amyloliquefaciens, Biosurfactant, Wound healing

Organic Synaptic Transistors with an Ultra‐Short‐Term Weight‐Reconstruction for Processing Multiple Types of Signals

AbstractAn organic synaptic transistor (OST) that utilizes a multiple‐annealing process and an ion gate to achieve significant reductions in operating voltage and increases in transconductance is demonstrated. The OST exhibits an ultra‐short‐term plasticity (USTP) with a maximum retention time of only 20.7 ms, which does not increase with the number and duration of spikes. This is the shortest retention time yet achieved by an ion‐gel‐regulated synaptic transistor. In addition, OST‐integrated array exhibits a tunable weight plasticity and a short weight refresh time for a stable image resetting in ample time of <0.2 s. It is also sensitive to the frequency and amplitude of electrical inputs; a low‐frequency suppression and a nonlinear amplitude gain enables OST‐constructed filter for use in processing multiple types of signals. This work is a step toward constructing high‐performance and multifunctional artificial intelligent systems.

V2O5 based artificial optical synaptic devices for neuromorphic computing

This paper proposed novel V2O5 based optical synaptic devices using wafer scalable microfabrication techniques. These V2O5 optical devices mimic the human brain like functions such as paired pulse facilitation (PPF), short term memory and long term memory. PPF index of 209 % which indicates promising short term memory behavior. The maximum retention time of 3.6 × 103 seconds was achieved. These V2O5 optical devices were used as synapses in an artificial neural network (ANN) to classify digits and alphabets with accuracy of 98.49 % and 97.58 % respectively. Thus, the proposed V2O5 based optical synaptic device integrated for real-world applications can be a breakthrough innovation in recognition that is computationally efficient.

Development of Synchronous Transportation Model for Trackless Vehicle Dispatching During the Construction of Long‐Distance Single‐Headed Shield Tunnel

With the increasing demands for long‐distance single‐headed tunnels, trackless vehicles have been widely accepted for transporting construction materials from storage yard to working face. During the trackless transportation of construction materials, the synchronization of material supply and shield tunneling is critical to ensure tunneling efficiency. However, there is still a lack of a reliable synchronous transportation model for trackless vehicle dispatching. In the present study, the material transportation processes and vehicle transportation parameters have been investigated based on the Sutong GIL Yangtze River Crossing Cable Tunnel. The synchronous transportation model has been established to improve transportation efficiency during the construction stage. An optimized scheme of vehicle schedule has been proposed to minimize trackless vehicle and retention time. Comparative analysis has been carried out to evaluate the trackless vehicle and retention time between the optimized scheme and the original scheme. The results indicate that the number of dual‐headed trucks required for material transportation decreases from nine to six, and the maximum retention time decreases from 166 to 35 min. Compared with the original scheme, the optimized scheme is available for reducing the number of trackless vehicles and improving the efficiency of material transportation. The present study contributes to optimizing material transport scheduling and synchronizing material supply with tunnel excavation in long‐distance single‐headed shield tunnels.

Identification of bio-active compounds in indigenous <i>Trichoderma asperellem</i> against <i>Fusarium oxysporum</i> f. sp. <i>ciceris:</i> A causal agent of chickpea wilt

Wilt caused by Fusarium oxysporum f. sp. ciceris (Padwick) is an important soil-borne disease and considered as most serious and widespread disease of chickpea throughout the world. Twenty indigenous isolates of Trichoderma spp. were isolated from the rhizosphere of chickpea in different geographic regions of Karnataka. Among twenty isolates, a higher concentration of volatile compounds was produced by TR-14 (72.22%) followed by TR-19 (66.67%) and TR-9 (65.93%). Further, the efficient strain that is TR-14 was identified as Trichoderma asperellum molecularly and was used to extract metabolites by using solvent extraction technique and subjected to GC-MS/MS analysis. The results have shown presence of twenty-nine compounds at different retention times ranging from 4.910 to 21.868 min. and the mass-to-charge (m/z) ratio from 43 to 190. Out of twenty-nine compounds, the concentration of 2-Imidazol-1-ylmethyl-pyridine 1-oxide (C9H9N3O) was highest with the maximum area (14375440) and retention time (19.842). Apart from this compound, 7-Isopropylidene-5-methyl-2, 3-diazabicyclo (2.2.1) hept-5-ene-2,3 dicarboxylic acid, diethyl ester was present at the highest peak with a retention time of 20.021.

Advanced strategies on update mechanism of tree-seed algorithm for function optimization and engineering design problems

Tree-seed algorithm (TSA) is one of the meta-heuristic algorithms proposed recently. It has a simple but effective structure. However, for complex high-dimensional functions and constrained optimization problems, TSA has the defects of slow convergence rate and low optimization accuracy. To overcome these issues, an improved tree-seed algorithm (SATSA) based on Nelder-Mead simplex method is proposed. Firstly, appropriately increase the value of the control parameters that balance exploration and exploitation, thereby improving the local search ability of TSA, and introduce an adaptive stochastic component of Gaussian distribution in the seed generation formula of the local search stage. Then, set the maximum retention times of each tree, for trees that exceed the maximum retention times in continuous iterations, increase the number of seeds produced by this tree, then use a new equation based on the global optimal location to generate seeds, thereby speeding up the convergence of the algorithm. Finally, after all trees produce seeds, introduce the improvement strategy with Nelder-Mead simplex method into some poor quality solutions, so that the solution with poor quality is searched deeply in the neighborhood, speeding up the process of moving the overall solution to the optimal solution. Its convergence is proved by theoretical analysis, and certifies that the time complexity of SATSA is not increased compared to TSA. The simulation results of 6 advanced algorithms on CEC2017 test suite and 10 challenging engineering constrained optimization problems demonstrate that the three strategies proposed in this study are feasibility and effectiveness.

Optimization of pyrolysis conditions for production of rice husk-based bio-oil as an energy carrier

Bio-oil is an eco-friendly energy source with potential to substitute fossil-derived fuels. This study optimized pyrolysis conditions for production of bio-oil from rice husks. Response surface methodology based on central composite design was employed to maximize bio-oil yield and high heating value (HHV) while minimizing water and ash contents. The pyrolysis process conditions were; temperature (400–650 °C), heating rate (6000–9750 °Ch-1), and holding time (600–1800 s). Analysis of variance revealed that the linear model best fits the responses of bio-oil yield and water content. On the other hand, the quadratic model best fits the responses of HHV and ash content. Pyrolysis temperature had the greatest influence on each of the studied responses, followed by holding time and lastly heating rate. Optimum pyrolysis conditions were found to be; temperature (650 °C), heating rate (9750 °Ch-1), and holding time (1800 s), leading to bio-oil yield, HHV, water and ash contents of 38.13%, 23.40 MJ/kg, 18.27%db and 0.16%db, respectively. These results fall in the range of standard quality values for bio-oil in published literature where >15 MJ/kg, 20–30%, 0.15–0.25% are the recommended ranges for HHV, water and ash contents, respectively. Results from the FTIR spectroscopy revealed that phenolic compounds contributed the most to bio-oil composition. Phenolic compounds positively influenced the quality of bio-oil due to their high calorific values. Gas chromatograph and mass spectrometry results showed peaks continuing to spill up to the maximum retention time indicating good thermal stability and bio-oil quality.

Pharmacokinetic Profiling of Prepared Artemisinin-Loaded Poly(lactic co-glycolic acid) Nanoparticles in Mice Infected with Artemisinin-Sensitive and-Resistant Plasmodium berghei K173 Using by HPLC-MS/MS Assay

Low solubility and bio-availability of artmisinin (ART) limit the clinical efficacy and unfortunately, the resistance of Plasmodium to ART has been gradually reported in recent years. In order to improve its dissolvebility, we therefore prepared ART-loaded poly(lactic co-glycolic acid) (PLGA) nanoparticles and characterized them. Later, the pharmacokinetic differences between ART original materials and artemisinin-loaded nanoparticles in mice infected with ART-sensitive and-resistant Plasmodium berghei K173 were investigated by orally administrated (40 mg/kg) by using a successfully developed and validated LC-MS/MS detection method. ART-loaded nanoparticles exhibited a smooth and spherical shape with average diameters of 193.80±7.65 nm. In vitro release results showed that ART-loaded nanoparticles displayed a stable sustained release effect. Meanwhile, the pharmacokinetic properties of ART-loaded nanoparticles were significantly improved when compared with the crude materials both in two groups. The AUC(0−t) significantly increased 2.91 and 2.85 folds as well as 4.03, 3.61 folds higher half-life period (t1/2) and 2.76, 3.27 folds higher maximum retention time (MRT), respectively. CL, meanwhile, declined 3.33 and 3.33 folds. These results suggested that ART-loaded nanoparticles enhanced the retention of ART in vivo and contributed to its long-lasting antimalarial effect.

Clearance and persistence of Escherichia coli in the freshwater mussel Unio mancus

The excessive use of antibiotics has led to the emergence of resistant bacteria, mainly from the Enterobacterales group, with high pathogenic/zoonotic potentials that can lead to problems in public health. The increasing presence in freshwater ecosystems highlights the need to evaluate potential sentinel species as risk indicators for both ecosystem and human health. The freshwater mussels provide several ecosystem services, may represent potential sentinel species due to their ability to filter water and retain both organic and inorganic particles. We tested the capability of U. mancus to retain Escherichia coli as a model bacterial organism. Under experimental conditions, the mussels could clear suspended E. coli, facilitating its rapid elimination from water within the first 24 h after exposure. The species also presented a maximum retention time of 4 days. We also provide allometric equations correlating the filtering capacity with the length and the weight of mussel body parts often used in biometric studies. We provide a first assessment of the potential of the bivalve Unio mancus to act as a sentinel species for the detection of Enterobacterales and demonstrate the ability to act as a water cleaner.

Caralluma tuberculata exhibits analgesic and anti-arthritic potential by downregulating pro-inflammatory cytokines and attenuating oxidative stress.

Caralluma tuberculata N.E. Brown (Common name: Chongan), belonging to the family Asclepiadaceae is distributed widely in hilly areas of Dir, Swat, Kohat and in plain lands of Punjab, Pakistan. The plant has been used as a source of vegetable as well as home remedy for headache, muscle spasms and rheumatism. The present study was proposed to investigate the analgesic, anti-inflammatory and anti-arthritic potential of the aqueous methanolic extract of C. tuberculata (ICE). The dried shoots of plant were used to prepare aqueous methanolic extract (30:70) by 3days thrice maceration and filtration followed by evaporation under reduced pressure. ICE was screened for the presence of phytochemicals using preliminary phytochemical analysis and HPLC. The antioxidant potential was evaluated through DPPH assay. Analgesic potential of ICE was studied using hot plate and tail immersion methods, and anti-inflammatory activity was performed using turpentine oil and carrageenan-induced inflammation models, in wistar albino rats. Formaldehyde-induced and Complete Freund's Adjuvant-induced arthritis models were used for the assessment of anti-arthritic activity of ICE and its effects on serum levels of PGE-2 as well as gene expression levels of pro-inflammatory cytokines were studied. ICE displayed a dose-dependent (300-1000mg/Kg p.o.) analgesic effect in hot plate (maximum retention time of 10.87 and 13s) and tail immersion (response time of 11 and 13.64s) tests at the doses of 500 and 1000mg/Kg, respectively. The extract exhibited a significant decrease in paw inflammation of rats at the doses of 500 and 1000mg/Kg as compared to the disease control group. ICE also exhibited a remarkable decline in arthritic score and a dose-dependent drop in serum levels of prostaglandin E2. There was a significant suppression in the expression of TNF-α, IL-1β, IL-6, NF-κB and cyclooxygenase enzyme in treatment groups. This study concludes that Caralluma tuberculata exhibits strong analgesic, anti-inflammatory, antioxidant and anti-arthritic activities thus upholding the vernacular use of the plant for pain and rheumatism.

Simultaneous brine recovery and water depollution in highly saline leather industry wastewater using a united halophiles supported nano porous carbon catalyst

The united water depollution of organic compounds and simultaneous brine recovery from leather industry saline wastewater (soak liquor contains 4–5% NaCl) using halophiles immobilized carbon reactors are investigated in this study. Initially, three active halophilic organisms such as Serratia marcescenssp., Citrobacter freundiisp., and Salmonella typhimuriumsp., were screened from the NaCl-organics acclimatized leather industry deep soil. The halophilic organism's growth parameters such as incubation time, pH, and temperature, salinity, and substrate concentrations were optimized. The halophiles united carbon catalyst was used in fluidized bed reactor (FICCO) and packed bed reactor (CAACO). The FICCO and CAACO reactors used to recover the brine from soak liquor which is free from the organics such as amino acids, glycerol, fatty acids, glucosamine and glucuronic acid derived from the treatment of protein, lipids and mucopolysaccharides containing soak liquor depolluted by SOAR- En-NPAC reactors. The SEM and AFM images reinforced the halophiles integrated on the surface of carbon matrix. The maximum retention time of 6 h, for water depollution from the organic compounds achieved by FICCO reactor at highly saline medium and the COD, 98%; BOD, 95%; TOC, 92%; TN, 93%; TSS, 85% and 92% of VS eliminated using FICCO and CAACO reactors. The final treated wastewater evaporated under solar incubation and the recovered brine was characterized by the analytical techniques such as SEM, XRD and ICP-OES used to verify the purity.

Acute Toxicity, Biodistribution, and Pharmacokinetics Studies of Pegylated Platinum Nanoparticles in Mouse Model

Pegylated colloidal platinum nanoparticles (PEG‐PtNPs) are widely used as a potential agent for diagnosis and therapy of various diseases including cancer. Prior to any preclinical applications, detailed investigations of toxicity, biodistribution, clearance, and pharmacokinetics (PKs) of new nanomaterials are essential. Extensive toxicological studies of PEG‐PtNPs are not reported in a systematic manner elsewhere. Herein, acute toxicity of PEG‐PtNPs is thoroughly investigated in mouse model. Prior to study in mice, a hemolytic analysis is performed with PtNPs that displays biocompatible nature. Administration of a single intraperitoneal dose of PEG‐PtNPs (10 and 50 mg kg−1 body weight) in mice does not induce any gross pathological changes. The data obtained from hematology, serum biochemistry, and histopathological analysis indicate no significant changes except for moderate nephrotoxicity at the higher dose. In addition, a PK analysis displays a maximum retention time and elimination half‐life at 10 mg kg−1 b.w. dose. Biodistribution studies demonstrate maximum accumulation of platinum in spleen tissue and tail of mice. Finally, detection of platinum in feces and urine confirms their excretion through a hepatobiliary system. Altogether, this study indicates that 10 mg kg−1 b.w. therapeutic dose of PEG‐PtNPs is safe for their potential future application in cancer theranostics.

Colonic Transendoscopic Enteral Tubing: Route for a Novel, Safe, and Convenient Delivery of Washed Microbiota Transplantation in Children.

Aim Colonic transendoscopic enteral tubing (TET) has been used for delivering fecal microbiota transplantation by washed preparation since 2015, which was recently named as washed microbiota transplantation (WMT). However, there are few reports available regarding the feasibility and safety of these studies in low-age population. This study is aimed at evaluating the safety, feasibility, and value of colonic TET in 3-7 years old children. Methods All patients aged 3-7 years who underwent colonic TET in our center for WMT or medication were prospectively evaluated. The feasibility and safety of TET were evaluated. A questionnaire was completed by the children's parents to evaluate the children's response to the colonic TET as well as the parent's satisfaction. Results Forty-seven children were included (mean age 5 years). TET was implemented into the colon of all the patients, and the success rate of the procedure was 100%. The median retention time of TET tube within the colon was 6 (IQR 5-7) days in 45 patients with tube falling out spontaneously, and the maximum retention time was up to 21 days. Multivariate analysis demonstrated that endoscopic clip number (P = 0.009) was an independent contributing factor for the retaining time of tube. With increase in the number of large clips, the retention time of TET tube was prolonged. No discomfort was reported during injection of the microbiota or medication suspension through the TET tube. During the follow-up, no severe adverse events were observed. All children's parents were satisfied with TET. Interestingly, the proportion of children's parents choosing TET as the delivery way of WMT increased from 29.79% before to 70.21% after TET (P < 0.001). Conclusions This study, for the first time, demonstrates that colonic TET is a novel, safe, and convenient colonic delivery way for WMT and medication in children aged 3-7 years.

Advanced chromatographic technique for performance simulation of anti-Alzheimer agent: an ensemble machine learning approach

This work employs the application of three artificial intelligence (AI) techniques namely; support vector machine (SVM), Hammerstein-Wiener (HW) and multi-layer perceptron (MLP) for predicting the qualitative properties of an anti-Alzheimer agent using high-pressure liquid chromatography technique. The mobile phase (inform of acetonitrile and trifluoroacetic acid) and the column temperature was used as the predictors in modelling the maximum retention time (tR-max) and resolution (Resol.) as the output variables of the analyte. The measured and predicted values were checked using three performance indices including; Nash–Sutcliffe efficiency (NSE), correlation coefficient (CC) as the goodness of fits and a statistical error inform of root-mean-square error (RMSE). The results obtained demonstrated the promising ability of AI-based models in modelling the qualitative properties of the anti-Alzheimer agent. Observation of different outputs of the AI-based models at various time intervals showed the necessity of ensembling the outputs of the AI-based models. Therefore, simple average ensemble and support vector machine ensemble (SVM-E) were employed to enhance the performance skills of the simple models. The comparative performance of SVM-E inform of NSE indicated its ability in boosting and enhancing the performance skills of the single models SVM, MLP and HW models up to 5, 13 and 20% respectively in the testing stage for modelling tR-max.

Colonic transendoscopic tube-delivered enteral therapy (with video): a prospective study

BackgroundColonic transendoscopic enteral tubing (TET) refers to colonic transendoscopic tube-delivered enteral therapy. Colonic TET has been successfully used for frequent colonic administration of drugs or multiple fecal microbiota transplantations (FMTs). This prospective observational study aimed to evaluate possible factors affecting methodology, feasibility and safety of colonic TET.MethodsPatients who underwent colonic TET at our center from October 2014 to November 2018 were included. The feasibility, efficacy, and safety of TET were evaluated.ResultsIn total, 224 patients were analyzed. The success rate of TET was 100%. The median retention time of TET tube within the colonic lumen was 8.5 (IQR 7–11) days in 158 patients with tube falling out spontaneously, and the maximum retention time was up to 28 days. These patients were divided into the short-retention group (≤ 8.5 days) and the long-retention group (> 8.5 days). Univariate and multivariate analysis demonstrated that the type of endoscopic clip (p = 0.001) was an independent factor for the retention time. The larger clips as well as a greater number of clips significantly affected the retention time (p = 0.013). No severe adverse event was observed during and after TET.ConclusionsColonic TET is a feasible, practical, and safe colon-targeted drug delivery technique with a high degree of patients’ satisfaction. Two to four large endoscopic clips are recommended to maintain stability of the TET tube within the colon for over 7 days.

Double-Gate Junctionless 1T DRAM With Physical Barriers for Retention Improvement

In this article, a double-gate (DG) junctionless (JL) transistor with physical barriers is proposed for one-transistor dynamic random-access memory (1T DRAM) application. In this topology, the holes are stored in the region blocked by physical barriers constructed by oxides underneath the source and drain regions rather than a potential well formed by n+-p-n+ as in the conventional structures. The proposed topology achieves an elongated retention time ( ${T}_{\text {ret}}$ ) with larger physical barrier thickness ( ${T}_{\text {oxPB}}$ ) and wider barrier offset length ( ${L}_{\text {BO}}$ ) due to a reduction in band-to-band tunneling (BTBT) (during hold “0”) and recombination (during hold “1”). Maximum retention times of ~2.5 s and ~33 ms have been achieved for channel doping of 1019 cm−3 at 27 °C and 85 °C, respectively, with gate length ( ${L}_{g}$ ) of 100 nm at small drain bias ( ${V}_{\text {DS}}$ ) of 1 V during write “1.” Results demonstrate a better gate length scalability and a retention time of ~4 ms at ${L}_{g}$ of 15 nm with thinner Si channel thickness under the gate ( ${T}_{\text {Si}}$ ) and thicker ${T}_{\text {oxPB}}$ . In addition, the effect of temperature on retention time has been analyzed. With optimized ${T}_{\text {oxPB}}$ at ${L}_{g} = {100}$ nm, the retention time decreases due to thermal generation and recombination from ~2.5 s at 27 °C to ~3 ms at 125 °C.

Periodic concentration-polarization-based formation of a biomolecule preconcentrate for enhanced biosensing.

Ionic concentration-polarization (CP)-based biomolecule preconcentration is an established method for enhancing the detection sensitivity of target biomolecules. However, the formed preconcentrated biomolecule plug rapidly sweeps over the surface-immobilized antibodies, resulting in a short-term overlap between the capture agent and the analyte, and subsequently suboptimal binding. To overcome this, we designed a setup allowing for the periodic formation of a preconcentrated biomolecule plug by activating the CP for predetermined on/off intervals. This work demonstrated the feasibility of cyclic CP actuation and optimized the sweeping conditions required to obtain the maximum retention time of a preconcentrated plug over a desired sensing region and enhanced detection sensitivity. The ability of this method to efficiently preconcentrate different analytes and to successfully increase immunoassay sensitivity underscore its potential in immunoassays serving the clinical and food testing industries.

Transmission characteristics of Tomato chlorosis virus (ToCV) by Bemisia tabaci MED and its effects on host preference of vector whitefly

The epidemiology of Tomato chlorosis virus (ToCV) in China is closely associated with its vector whitefly, Bemisia tabaci (Gennadius) MED. However, the transmission characteristics of ToCV by B. tabaci MED remain poorly understood. In this study, we analyzed: 1) the horizontal and vertical transmission of ToCV by B. tabaci MED whiteflies; 2) the acquisition of ToCV by male and female B. tabaci MED whiteflies after different feeding durations; 3) the transmission efficacy of viruliferous male and female B. tabaci MED whiteflies after different inoculation access periods (IAPs); 4) the retention of ToCV by viruliferous male and female B. tabaci MED whiteflies after a 48 h acquisition access period (AAP); and 5) the effects of ToCV on host choice of healthy or ToCV-infected tomato plant of viruliferous and non-viruliferous B. tabaci MED at different time points. Our results showed that: 1) viruliferous males could not transfer ToCV to non-viruliferous females, and vice versa, viruliferous females could not pass on ToCV to non-viruliferous males. ToCV could not be detected in the F1 generation adults; 2) ToCV could be detected within 4.0% of females or males after a 20 min AAP; 3) ToCV could be detected in 33.3% of tomato plants inoculated by 10 viruliferous males or females with IAPs of 20 or 30 min; 4) the maximum retention time in females was 7 and 5 days in males; and 5) non-viruliferous B. tabaci MED did not show a preference for ToCV-infected tomato plants or healthy tomato plants. However, viruliferous B. tabaci MED whiteflies did prefer to settle on healthy tomato plants over ToCV-infected tomato plants. These findings will be helpful to better understand the epidemiology of the recently emerged plant virus, ToCV, in tomato fields in China.

SREA: A self-recovery effect aware wear-leveling strategy for the reliability extension of NAND flash memory

With aggressive scaling and multilevel cell technology, the reliability and lifetime of the NAND flash degrades. To address this issue, a Self-Recovery Effect Aware (SREA) strategy is proposed to extend the storage reliability of the NAND flash. The key purpose of SREA is a wear-leveling strategy based on the self-recovery effect of the NAND flash. First, this study verifies the self-recovery effect of the NAND flash based on our hardware-software codesigned experimental platform; then, we propose the concept of relaxation time (tr). The change rule of the data retention error under different degrees of tr for blocks subjected to different program/erase (P/E) cycles is also investigated. The experimental results show that there is an approximately 60% gap of retention error rate when tr = 0 h and tr = 6 h after the same retention time. In addition, we apply the experimental rules to the wear-leveling strategy. Compared with the traditional wear-leveling strategy that does not consider tr, the maximum data reliable retention time of SREA can be extended by 2.67×.

Effect of Si particle size and NH4Cl additive on combustion synthesis of α-Si3N4

High α-phase content Si3N4 powders were fabricated by combustion synthesis method using coarse Si powder with NH4Cl additive. The effects of Si particle size and NH4Cl additive on the macrokinetic feature, phase composition, microstructure of combustion synthesized α-Si3N4 powder were investigated. Without the addition of NH4Cl, the content of α-Si3N4 in the products first decreases under a critical Si particle size of 7.8 μm, and then increases with increasing Si particle size. With the addition of 6 wt% NH4Cl, high α-phase content Si3N4 powder (>90 wt%) was obtained by using coarse (19.6 μm) Si powder. The addition of NH4Cl reduces the maximum combustion temperature and retention time of liquid Si by promoting the gasification of Si, which lead to the increase of α-Si3N4 content in the product. The use of coarse Si powder is of great significance for the low-cost production of high-quality α-Si3N4 powder.