Extra Process Research Articles

Dual autoencoders modeling of electronic health records for adverse drug event preventability prediction

BackgroundElderly patients are at increased risk for Adverse Drug Events (ADEs). Proactively screening elderly people visiting the emergency department for the possibility of their hospital admission being drug-related helps to improve patient care as well as prevent potential unnecessary medical costs. Existing routine ADE assessment heavily relies on a rule-based checking process. Recently, machine learning methods have been shown to be effective in automating the detection of ADEs, however, most approaches used only either structured data or free texts for their feature engineering. How to better exploit all available EHRs data for better predictive modeling remains an important question. On the other hand, automated reasoning for the preventability of ADEs is still a nascent line of research. MethodsClinical information of 714 elderly ED-visit patients with ADE preventability labels was provided as ground truth data by Jeroen Bosch Ziekenhuis hospital, the Netherlands. Methods were developed to address the challenges of applying feature engineering to heterogeneous EHRs data. A Dual Autoencoders (2AE) model was proposed to solve the problem of imbalance embedded in the existing training data. ResultsExperimental results showed that 2AE can capture the patterns of the minority class without incorporating an extra process for class balancing. 2AE yields adequate performance and outperforms other more mainstream approaches, resulting in an AUPRC score of 0.481. ConclusionsWe have demonstrated how machine learning can be employed to analyze both structured and unstructured data from electronic health records for the purpose of preventable ADE prediction. The developed algorithm 2AE can be used to effectively learn minority group phenotype from imbalanced data.

Zero-Dimensional Lead-Free Halide with Indirect Optical Gap and Enhanced Photoluminescence by Sb Doping.

Three new lead-free organic-inorganic metal halides (OIMHs) (C7H8N3)3InX6·H2O (X = Cl, Br) and (C7H8N3)2SbBr5 were synthesized. First-principles calculations indicate that the highest occupied molecular orbitals (HOMOs) of the two In-based OIMHs are constituted of π orbitals from [C7H8N3]+ spacers. (C7H8N3)3InX6·H2O (X = Cl, Br) shows an indirect optical gap, which may result from this organic-contributed band edge. Despite the indirect-gap nature with extra phonon process during absorption, the photoluminescence of (C7H8N3)3InBr6·H2O can still be significantly enhanced through Sb doping, with the internal photoluminescence quantum yields (PLQY) increased 10-fold from 5% to 52%. A white light-emitting diode (WLED) was fabricated based on (C7H8N3)3InBr6·H2O:Sb3+, exhibiting a high color-rendering index of 90. Our work provides new systems to deeply understand the principles for organic spacer choice to obtain the 0D metal OIMHs with specific band structure and also the significant enhancement of luminescence performance by chemical doping.

Optimized algorithm for evapotranspiration retrieval via remote sensing

Many algorithms for surface energy balance (SEB) based on remote sensing (RS) have been advanced to determine evapotranspiration (ET). These algorithms were developed for specific conditions (e.g., sensors, land use, and crop management) in which functions and empirical parameters within its algorithms concur with those conditions. Therefore, this study aims to develop a SEB-RS algorithm for retrieving ET adjusted to in situ observations. The study was conducted in two experimental fields in Brazil with the crops Jatropha curcas, maize, soybean, and sugarcane. We used multispectral images from the orbital sensors, Operational Land Imager (OLI) and Thermal Infrared Sensor (TIRS) coupled in Landsat 8 satellite and from the terrestrial sensor, Altum, on board of an unmanned aerial vehicle. The proposed algorithm termed as Ground-truthed Surface Energy Balance (GT-SEB) is based on physical formulation of SEB-RS algorithms, where two extra computational processes using in situ ET observations were proposed for originating the new algorithm. The first additional process for optimizing the automatic “anchor” pixels selection and another for algorithm parameters optimization. Thus, both processes aim to reduce the difference between the observed ET and estimated by GT-SEB. Being assessed for both orbital (OLI/TIRS) and suborbital (Altum) sensors, the GT-SEB yielded excellent results (root-mean-square-error, RMSE, ≤ 0.48 mm and modified Kling-Gupta efficiency, KGE, ≥ 0.92). In addition to GT-SEB being an optimized algorithm, it uses a classic parameterization of SEB-RS algorithms, providing efficiency and scalability for other remote sensors, climates, and surfaces.

A high-precision 2D DOA estimation algorithm by a large-space three-parallel array for reducing mutual coupling

In this paper, a high-precision two-dimensional (2D) direction of arrival (DOA) estimation algorithm by three parallel uniform linear arrays (ULAs) is proposed. Both the internal spacing of each sub-array and the spacing between two adjacent sub-arrays can exceed the half-wavelength of incident signal. An extended propagator method (PM) algorithm is introduced to obtain a multiple extended propagator matrix by processing the covariance matrix of received signals. Then, by using the extended propagator matrix, unambiguous and high-precision 2D DOA estimation can be obtained without extra pairing process. For the proposed array construction, mutual coupling effect can be ignored as long as the element interval is large enough. The extended PM algorithm based on the proposed array has far higher precision than the existing similar algorithms, which can be proved by some simulation experiments.

Lithium Enrichment Signatures of Planetary Engulfment Events in Evolved Stars

Abstract Planetary engulfment events have long been proposed as a lithium (Li) enrichment mechanism contributing to the population of Li-rich giants (A(Li) ≥ 1.5 dex). Using MESA stellar models and A(Li) abundance measurements obtained by the GALAH survey, we calculate the strength and observability of the surface Li enrichment signature produced by the engulfment of a hot Jupiter (HJ). We consider solar-metallicity stars in the mass range of 1–2 M ⊙ and the Li supplied by a HJ of 1.0 M J. We explore engulfment events that occur near the main-sequence turn-off (MSTO) and out to orbital separations of R ⋆ ∼ 0.1 au = 22 R ⊙. We map our results onto the Hertzsprung–Russell Diagram, revealing the statistical significance and survival time of Li enrichment. We identify the parameter space of masses and evolutionary phases where the engulfment of a HJ can lead to Li enrichment signatures at a 5σ confidence level and with meteoritic abundance strengths. The most compelling strengths and survival times of engulfment-derived Li enrichment are found among host stars of 1.4 M ⊙ near the MSTO. Our calculations indicate that planetary engulfment is not a viable enrichment pathway for stars that have evolved beyond the subgiant branch. For these sources, observed Li enhancements are likely to be produced by other mechanisms, such as the Cameron–Fowler process or the accretion of material from an asymptotic giant branch companion. Our results do not account for second-order effects, such as extra mixing processes, which can further dilute Li enrichment signatures.

Oxygen and aluminum-magnesium isotopic systematics of presolar nanospinel grains from CI chondrite Orgueil

Presolar oxide grains have been divided into several groups (Group 1 to 4) based on their O isotopic compositions, which can be tied to several stellar sources. Much of the available data was acquired on large grains, which may not be fully representative of the presolar grain population present in meteorites. We present here new O isotopic data for 74 small presolar oxide grains (∼200 nm in diameter on average) from Orgueil and Al-Mg isotopic systematics for 25 of the grains. Based on data-model comparisons, we show that (i) Group 1 and Group 2 grains more likely originated in low-mass first-ascent (red giant branch; RGB) and/or second-ascent (asymptotic giant branch; AGB) red giant stars and (ii) Group 1 grains with (26Al/27Al)0 ⪆ 5 × 10−3 and Group 2 grains with (26Al/27Al)0 ⪅ 1 × 10−2 all likely experienced extra circulation processes in their parent low-mass stars but under different conditions, resulting in proton-capture reactions occurring at enhanced temperatures. We do not find any large 25Mg excess in Group 1 oxide grains with large 17O enrichments, which provides evidence that 25Mg is not abundantly produced in low-mass stars. We also find that our samples contain a larger proportion of Group 4 grains than so far suggested in the literature for larger presolar oxide grains (≥400 nm). We discuss this observation in the light of stellar dust production mechanisms.

A visual-degradation-inspired model with HSV color-encoding for contour detection

BackgroundGiven energy metabolism, visual information degradation plays an essential role in the retina- lateral geniculate nucleus (LGN)-primary visual cortex (V1)-secondary visual cortex (V2) pathway, and is a pivotal issue for visual information processing. Degradation helps the visual nervous system conserve brain energy and efficiently perceive the real world even though a small fraction of visual information reaches the early visual areas. The coding of contour features (edge and corner) is achieved in the retina-LGN-V1-V2 pathway. Based on the above, we proposed a contour detection model based on degradation (CDMD). New methodInspired by pupillary light reflex regulation, we took into consideration the novel approach of the hue-saturation-value (HSV) module for color encoding to meet the subtle chromaticity change rather than using the traditional red-green-blue (RGB) module, following the mechanisms of dark (DA) and light (LA) adaptation processes in photoreceptors. Meanwhile, the degradation mechanism was introduced as a novel strategy focusing only on the essential information to detect contour features, mimicking contour detection by visual perception under the restriction of axons in each optic nerve biologically. Ultimately, we employed the feedback mechanism achieving the optimal HSV value for each pixel of the experimental datasets. ResultsWe used the publicly available Berkeley Segmentation Data Set 500 (BSDS500) to assess the effectiveness of our CDMD model, introduced the F-measure to evaluate the results. The F-measure score was 0.65, achieved by our model. Moreover, CDMD with HSV has a better sensitivity for subtle chromaticity changes than CDMD with RGB. Comparison with existing methodsExperimental results demonstrated that our CDMD model, which functions close to the real visual system, achieved a more competitive performance with low computational cost than some state-of-the-art non-deep-learning and biologically inspired models. Compared with deep-learning-based algorithms, our model contains fewer parameters and computation time, does not require additional visual features, as well as an extra training process. ConclusionsOur proposed CDMD model is a novel approach for contour detection, which mimics the cognitive function of contour detection in early visual areas, and realizes a competitive performance in image processing. It contributes to bridging the gap between the biological visual system and computer vision.

Melt volatile budgets and magma evolution revealed by diverse apatite halogen and trace elements compositions: A case study at Pulang porphyry Cu-Au deposit, China

Apatites those shielded as inclusions in igneous minerals are avoided of diffusion effects associated with evolving melts and can record the original volatile and trace element evolutions of the magma. Volatile and trace element compositions of apatites enclosed in high-Al, medium-Al, low-Al amphibole, magmatic biotite, plagioclase, and groundmass from ores, quartz monzonite porphyry (QMP) and its mafic microgranular enclaves (MMEs), and pre-ore coarse-grained quartz diorite porphyry (CQD) were present to evaluate the magmatic processes in the formation of Pulang porphyry Cu-Au deposit. All apatite inclusions are magmatic fluorapatites and occur as early-crystallization phases (940–980 °C), followed by the crystallization sequence of high-Al amphibole, medium-Al amphibole, magmatic biotite, plagioclase, low-Al amphibole (altered medium-Al amphibole) with fluctuating ƒO2 conditions. Compared to the low SO3 (<0.27 wt%) concentrations of other apatites inclusions in fertile QMP, the biotite-hosted apatites retain an abnormal SO3 (0.15–1.01 wt%) and Cl (0.08–0.71 wt%) enrichment. Estimates of sulfur and chlorine concentrations using partitioning models for apatite in QMP return similar features, where the biotite-hosted apatites yield highly variable melt S (315–2025 ppm) and Cl (0.1–1.2 wt%) contents. The presence of biotite-hosted S-Cl enriched apatites with overgrowth texture, together with the resorbed medium-Al amphiboles in QMP, both suggest that they have crystallized from an extra sulfur supplement process caused by the injection of a series of S-Cl enriched magma, and even subsequent remelting of the preexisting dioritic batholith and its interior apatites. Such magma processes further account for the fluid exsolution and alteration from medium-Al amphiboles to low-Al ones. Whereas, those from the barren CQD systematically returns normal SO3 (0.18–0.70 wt%) and Cl (0.03–0.51 wt%) concentrations with estimates of melt S (335–1321 ppm) and Cl (0.1–0.5 wt%) contents exhibiting features of typical arc basalts (300–1000 ppm; 0.01–0.85 wt%, respectively). Although the acicular apatite of MMEs has normal SO3 contents (0.19–0.37 wt%), its abundance also confirm an extra sulfur supplement process. The altered apatites of both QMP and CQD showing pitted surface with visible voids and LREE-rich mineral inclusions return low SO3 (<0.06 wt%) and Cl (<0.22 wt%) concentrations, indicating that these elements were depleted during potassic and phyllic alteration.Given that Sr/Y ratios (2.21–3.62) of apatite at Pulang do not vary significantly with changing melt composition (Mg = 119.1–528.8 ppm), the Sr/Y and Eu/Eu* ratios of apatite from QMP have confirmed a water-rich, oxidized magma origin, whereas the CQD are originated from a water-poor, reduced source. Besides, the hydrothermal alteration possibly accounts for the abnormally increased Ce/Ce* ratios of altered apatites from CQD and decreased Sr/Y ratios of the low-Al amphibole-hosted apatite from QMP. Therefore, using trace elements as indicators for petrogenetic studies would be more robust for those apatites enclosed in igneous minerals. Our studies demonstrate that apatite inclusions can be linked to discrete periods in the crystallization history of its host phases, thus providing insight into the magma evolution process.

Ensuring radiation safety during temporary storage of solidified radioactive waste in light hangar-type facilities

Expensive permanent storage facilities with massive engineered structures are used traditionally to ensure safe temporary storage of solidified radioactive waste at the NPP sites. Such approach is dictated by the need to comply with the regulatory requirements for limiting the gamma background in the area adjacent to the storage facility. The costs involved in temporary storage of solidified RW can be optimized by using light hangar-type storage facilities. At the same time, the safety of storage, including radiation protection of the personnel, the public and the environment, is undoubtedly ensured through the use of special organizational and engineering solutions. The Novovoronezh NPP, a branch of JSC Concern Rosenergoatom, operates successfully light hangar-type facilities for temporary storage of solidified RW classified as medium-level waste in accordance with OSPORB-99/2009. In the process of operation, a methodology and a method for conditioning and temporary storage of solidified RW were developed to ensure the RW removal for final disposal with no extra process operations and unreasonable costs. A methodology has been developed to assess the radiation situation around storage facilities during temporary storage of RW, as well as a software package for predicting the radiation situation when deciding on the arrangement of the storage facility’s peripheral rows.

An on-chip TVS design to meet system level ESD protection for RS485 transceiver

RS485 interface is widely used in the area of industrial control and remote meter reading, which are often subjected to serious electrostatic damage. A new On-Chip TVS (OCT) structure without extra process modification and a novel electrostatic discharge method for RS485 transceiver IC have been proposed. It is composed of a serie of Zener diodes and fabricated in 5V/18V/24V 0.5µm CDMOS technology. A 100ns pulse width of the Transmission Line Pulsing (TLP) test is performed for this proposed OCT. The driver circuit itself can work as an ESD device as well. The OCT trigger voltage is compatible with the signal level of RS485 standard. The OCT device protection level of human-body-model (HBM) is up to 16.34kV. RS485 transceiver integrated with OCT has also been tested in order to verify its reliability. The results indicate that it can pass the IEC61000-4-2 contact ±10kV stress and IEC 61000−4−4 Electrical Fast Transient (EFT) ±2.2kV without any hard damages and latch-up issues. The RS485 transceiver integrated with the OCT allows error-free data rate transfer up to 500 kbps. The chip occupies a silicon area of 2.4×1.17mm2.

Gamma-irradiated SARS-CoV-2 vaccine candidate, OZG-38.61.3, confers protection from SARS-CoV-2 challenge in human ACEII-transgenic mice

The SARS-CoV-2 virus caused the most severe pandemic around the world, and vaccine development for urgent use became a crucial issue. Inactivated virus formulated vaccines such as Hepatitis A and smallpox proved to be reliable approaches for immunization for prolonged periods. In this study, a gamma-irradiated inactivated virus vaccine does not require an extra purification process, unlike the chemically inactivated vaccines. Hence, the novelty of our vaccine candidate (OZG-38.61.3) is that it is a non-adjuvant added, gamma-irradiated, and intradermally applied inactive viral vaccine. Efficiency and safety dose (either 1013 or 1014 viral RNA copy per dose) of OZG-38.61.3 was initially determined in BALB/c mice. This was followed by testing the immunogenicity and protective efficacy of the vaccine. Human ACE2-encoding transgenic mice were immunized and then infected with the SARS-CoV-2 virus for the challenge test. This study shows that vaccinated mice have lowered SARS-CoV-2 viral RNA copy numbers both in oropharyngeal specimens and in the histological analysis of the lung tissues along with humoral and cellular immune responses, including the neutralizing antibodies similar to those shown in BALB/c mice without substantial toxicity. Subsequently, plans are being made for the commencement of Phase 1 clinical trial of the OZG-38.61.3 vaccine for the COVID-19 pandemic.

Scalable Solvent-Based Fabrication of Thermo-Responsive Polymer Nanocomposites for Battery Safety Regulation

Improving lithium-ion battery (LIB) safety remains a challenging task when compared with the tremendous progress made in their performance in recent years. Embedding thermo-responsive polymer switching materials (TRPS) into LIB cells has been proved to be a promising strategy to provide consistent thermal abuse protections at the coin-cell level. However, it is unrealistic to achieve large-scale applications without further demonstration in high-capacity pouch cells. Here, we employed tungsten carbide as a novel conductive filler, and successfully overcame the intrinsic processing difficulty of polyethylene matrix in a scalable solvent-based method to obtain ultra-thin, uniform, highly conductive TRPS. Moreover, by integrating TRPS directly into LIB electrodes, no extra fabrication facilities or processes are required for making the cells. As a result, multi-layer pouch cells with consistent electrochemical performance and thermal abuse protection function were fabricated using industry-relevant manufacturing techniques, which brings TRPS one step further to the real application scenarios.

A Review Of Reverse Osmosis Membrane Fouling: Formation and Control

Membrane application in reverse osmosis (RO) membrane is getting more attention especially in producing drinking water. However, RO membrane faces challenges that reduces its performance such as its permeation flux, salt rejection, additional energy demand, lifetime decrease, extra pre-treatment process, cleaning and maintenance. The challenge is the formation of fouling. RO membrane fouling can happen inside or outside the membrane and the characteristics of membrane fouling differs from one type to other types, depending on the nature and location of membrane fouling. There are several types of RO fouling, which are Biofouling, Organic Fouling, Inorganic Fouling and Colloidal Fouling. The causes of RO membrane are different from one to another. The properties and materials of the solution entering RO membrane are important as it affects the type of fouling of RO membrane fouling. All of the RO membrane foulings need to be considered during membrane usage and demand solution to be controlled. In order to control the fouling in Reverse Osmosis membrane, there have been several control solutions discovered to the membrane fouling challenges. The control solutions are specified to each one of the fouling, in spite of wide applications for some of it. The control solutions are pre-treatment, which has many methods such as photo oxidation, coagulation, scale inhibitor, ion exchange resins, granular media and membrane treatment, membrane monitoring, membrane cleaning, surface modification, and material addition to membrane or novel membrane material. With various control solutions discovered, the RO membrane still faces fouling issue and is still demanding some more advanced applicable control solutions.

Gold nanoparticle-assisted SELEX as a visual monitoring platform for the development of small molecule-binding DNA aptasensors

To resolve time-consuming and imperceptible monitoring problems in the traditional systematic evolution of ligands by exponential enrichment (SELEX), we report gold nanoparticle-assisted SELEX (GNP-SELEX) as a visual, proofreading, and self-monitoring platform and its application to small molecule-binding single-stranded DNA (ssDNA) aptasensors. Through the colorimetric changes between rounds, GNP-SELEX enabled the rapid determination of target-specific aptamer library enrichment with neither target modification nor extra monitoring process. We identified ssDNA aptamers with high selectivity and binding affinity by targeting two small molecules (brassinolide; BL and bisphenol A; BPA) as a model. The rational design of selected aptamers by 3D molecular simulation increased their ability to detect BL or BPA in real samples as bioreceptors. These results suggest that GNP-SELEX is useful as a self-monitoring platform to discover ssDNA aptamers as well as to develop aptasensors for diverse targets in a rapid and simple way.

A Versatile Crosslinking Strategy on Facile Fabrication of Fluorescent Hydrogels via o‐Phthalaldehyde Ternary Condensation

Main observation and conclusionIt is of great significance to develop rapid crosslinking strategies to enrich the functions of hydrogels and simplify the preparation process of hydrogels. Herein, we applied the ternary condensation reaction of o‐phthalaldehyde (OPA) with thiol and amino moieties to construct hydrogel networks with fast gelation rate, excellent mechanical strength, and favorable stability. The obtained hydrogels exhibited rapid gelation transition even at a low solid content. The ternary condensation was traced in the gelation process and demonstrated as a pseudo‐first‐order reaction irrespective of the gelation threshold. Interestingly, the crosslinking sites of these hydrogels were constructed with isoindole rings, endowing the materials with fluorescent functions without an extra chemical grafting process. The OPA ternary condensation reaction was a simple and universal strategy towards fabrication of natural or synthetic polymer gels from polysaccharides, proteins, and synthetic polymers, which is expected to have potential biomedical applications.

Innovative biosynthesis of silver nanoparticles using yeast glucan nanopolymer and their potentiality as antibacterial composite.

Nanometals (NM) frequently possess potent antimicrobial potentials to combat various pathogens, but their elevated biotoxicity limits their direct applications. The biosynthesis of NM and their capping/conjugation with natural biopolymers can effectually enhance NM stability and diminish such toxicity. Yeast β-glucan (βG), from Saccharomyces cerevisiae, was extracted and transformed to nanoparticles (NPs) using alkali/acid facile protocol. The βG NPs were innovatively employed for direct biosynthesis of silver nanoparticles (Ag NPs) without extra chemical processes. The physicochemical assessments (Fourier-transform infrared, X-ray diffraction, and transmission electron microscopy) validated NPs formation, interaction, and interior capping of Ag NPs in βG NPs. The synthesized βG NPs, Ag NPs, and βG-Ag NPs composite were negatively charged and had minute particlesizes with mean diameters of 58.65, 6.72, and 63.88 nm, respectively. The NPs (plain Ag NPs and composited βG-Ag NPs) exhibited potent comparable bactericidal actions, opposing Gram+ (Staphylococcus aureus) and Gram- (Escherichia coli, Salmonella Typhimurium, and Pseudomonas aeruginosa). Scanning micrographs, of treated S. aureus and S. Typhimurium with βG-Ag NPs, elucidated the powerful bactericidal actions of nanocomposite for destructing pathogens' cells. The inventive Ag NPs biosynthesis with βG NPs and the combined βG-Ag NPs nanocomposites could be impressively recommended as powerful antibacterial candidates with minor potential toxicity.

Investigation on in-situ thermal treatment of room-temperature pulsed laser deposition technique: How to improve Cu2ZnSnS4 films for photoelectric application without sulfurization

Is extra sulfurization an indispensable process for synthesizing quaternary chalcogenide? The answer is probably affirmative for most synthesismethods to suppress excessive sulfur vacancies. Pulsed laser deposition (PLD), an acknowledged technique for fabricating films with complex stoichiometry, is a greatalternative approach to prepare Cu2ZnSnS4 (CZTS) films. However, to prevent evaporative losses the deposition temperature (Tis) must be limited below 400 °C, which makes post-annealing process extremely requisite to improve metastable films. Herein we develop an in-situ thermal treatment technique in room-temperature (RT)-PLD-synthesis of CZTS films to evade extra sulfurization process. According to multi-peaks Gaussian fitting analysis, RT-PLD implementing optimized in-situ treatment can broaden solar absorption of CZTS films, potentially contributed by sub-bandgap absorption due to intrinsic natural-intermedium-band effects of I2-II-IV-VI4 chalcogenide compounds. Stabilized chronoamperometry characterization combined with quasi-stoichiometric ratio demonstrates that the RT-PLD technique can equivalently restrain sulfur vacancy generation even without sulfurization. Physical mechanisms associated to order–disorder transitions of polycrystal CZTS during in-situ treatment can interpret morphological “lumpy-smooth-vuggy” transformation along with Tis varied. Therefore, such proposed RT-PLD technique is applicable to prepare polynary compounds with volatile elements and complicated stoichiometry ratio.

Enhancing thermal stability and photoluminescence of red-emitting Sr2Si5N8:Eu phosphors via boron doping

• Demonstrating a new approach to enhanced photoluminescence via boron doping in red-emitting Sr 2 Si 5 N 8 :Eu 2+ phosphors. • Thermal degradation stability can be enhanced at the same time. • Combining experimental and first principles calculations, the mechanism of B-doping can be understood. Surface passivation is a common method to improve the resistance of thermal degradation of nitride phosphors. However, such a surface passivation generally needs extra processes and decreases the photoluminescence property of the phosphors. In this work, both the thermal stability and photoluminescence property of a red phosphor Sr 2 Si 5 N 8 :Eu are improved through the addition of BN. The influence of B on the crystal structure and the valence state of active ions was analyzed by experimental characterization. First-principles calculations were applied to analyze the formation energy of N vacancies, which influence the resistance of thermal degradation. Finally, combining with experimental characterization and calculations, the enhancing mechanism of thermal stability and photoluminescence by B was studied.

Current relaxation in the Random Resistor cum Tunnelling Network Model through first-passage route: Regimes and time-scales

Numerically we study the bulk current relaxation in percolative Random Resistor cum Tunnelling Network (RRTN) model through a first-passage route. The RRTN considers an extra semi-classical barrier-crossing process over a voltage threshold within a framework of classical RRN bond percolation model. We identify the different temporal regimes of relaxation and corresponding phenomenological time-scales, which fix up the extents of different regimes. These time-scales were previously identified in Refs. Bhattacharya (2019) and Sen and Mozumdar (2007). We investigate on the distributions of these time-scales and observe that there exists a perfect correlation among them in the thermodynamic limit. We conclude that there exists a single time-scale which controls the RRTN dynamics. The variation of mean first-passage time .vs. system size seems to be due to sub-diffusive motion of charge carrier through the network.

Ultrasonic machining of carbon fiber–reinforced plastic composites: a review

Carbon fiber–reinforced plastic (CFRP) composites are extensively being applied in manufacturing sectors because of their extraordinary characteristics. However, CFRP composites often require some extra machining processes to improve the dimensional accuracy and component integrity of CFRP composites in manufacturing industries. The ultrasonic machining (USM) process progressively has been examined due to its greater ability in machining difficult to cut, brittle, and hard materials such as CFRP composites and due to its relatively low machining cost. Furthermore, USM shows to be a promising process with better surface quality, lower cutting force, less or no fiber fracture, laminate delamination, and lower tool wear rate. Recently, USM has been extensively investigated by many researchers for the machining of CFRP composites. This paper explores the literature and presents a comprehensive review of the advances in USM of CFRP composites by classifying the studies reported in two perspectives. First, the review summarizes most of the reported studies starting from 2011 to 2020 based on the applied USM process, equipment/system/platform used to carry out experiments, considered process parameters and output variables, and challenges investigated or gap filled. Then, the reported studies are summarized considering the type of USM process variant, CFRP composite, adopted process parameters on machining characteristics, and their respective results and conclusions. The aim is to present the current research status in USM of CFRP composites and thus provide guidance and foundation for future research.