Genome-wide CRISPR/Cas9 screening for drug resistance in tumors

Genome-wide clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR associated nuclease 9 (Cas9) screening is a simple screening method for locating loci under specific conditions, and it has been utilized in tumor drug resistance research for finding potential drug resistance-associated genes. This screening strategy has significant implications for further treatment of malignancies with acquired drug resistance. In recent years, studies involving genome-wide CRISPR/Cas9 screening have gradually increased. Here we review the recent application of genome-wide CRISPR/Cas9 screening for drug resistance, involving mitogen-activated protein kinase (MAPK) pathway inhibitors, poly (ADP-ribose) polymerase inhibitors (PARPi), alkylating agents, mitotic inhibitors, antimetabolites, immune checkpoint inhibitors (ICIs), and cyclin-dependent kinase inhibitors (CDKI). We summarize drug resistance pathways such as the KEAP1/Nrf2 pathway MAPK pathway, and NF-κB pathway. Also, we analyze the limitations and conditions for the application of genome-wide CRISPR/Cas9 screening techniques

Bibliometric Analysis of Global Remote Sensing Research during 2010–2015

Bibliometric analysis based on the Science Citation Index Expanded published by Thomson Scientific was carried out to identify the research status and future trends of remote sensing (RS) during 2010–2015. The analysis revealed the institutional, national, spatio-temporal, and categorical patterns in remote sensing research both from the WP (whole publications) viewpoint and the HCP (highly-cited publications) viewpoint. Statistical analysis results showed that remote sensing research almost doubled during 2010–2015. Environmental sciences comprised the most attractive subject category among remote sensing research. The International Journal of Remote Sensing was the most productive journal, and Remote Sensing of Environment published the most HCP among the 31 distributed journals. The productive ranking of countries was led by the U.S. both from the WP viewpoint and the HCP viewpoint, and CAS (Chinese Academy of Sciences) was the most productive institute both from the WP viewpoint and the HCP viewpoint with lower CPP (average number of citations per paper). Keyword analysis illustrated that model and algorithm research were the key points in RS during 2010–2015. RS data including Moderate-Resolution Imaging Spectroradiometer (MODIS), Landsat, synthetic aperture radar (SAR), and LiDAR (light detection and ranging) were the most frequently adopted, but the data usage of UAVs (unmanned aerial vehicles) and small satellites will be promoted in the future. With the development of data acquisition abilities, big data issues will become the challenges and hotspots of RS research, and new algorithms will continue to emerge

Mass and Heat Transfer of Pressure Swing Adsorption Oxygen Production Process with Small Adsorbent Particles

Rapid-cycle pressure swing adsorption (PSA) with small adsorbents particles is intended to improve mass transfer rate and productivity. However, the mass transfer mechanisms are changed with reduction of particle size during rapid-cycle adsorption process. A heat and mass transfer model of rapid-cycle PSA air separation process employing small LiLSX zeolite particles is developed and experimentally validated to numerically analyze the effects of mass transfer resistances on the characteristics of cyclic adsorption process. Multicomponent Langmuir model and linear driving force model are employed for characterizing the adsorption equilibrium and kinetic. The results of numerical analysis demonstrate that the dominant mass transfer resistance of small adsorbents particles is a combination of film resistance, axial dispersion effect and macropore diffusion resistance. The oxygen purity, recovery and productivity of the product are overestimated by ~2–4% when the effect of axial dispersion on mass transfer is ignored. As particle size decreases, the front of nitrogen-adsorbed concentration and gas temperature become sharp, which effectively improves the performance. However, the adverse effect of axial dispersion on the mass transfer becomes significant at very small particles conditions. It is nearly identical shapes of nitrogen concentration and gas temperature profiles after adsorption and desorption steps. The profiles are pushed forward near the production end with an increase in bed porosities. The optimal oxygen recovery and productivity are achieved with a particle diameter of 0.45 mm and bed porosity of 0.39 during the PSA process

Safe Separation of the Low-Concentration and Oxygen-Bearing Coal Mine Methane by Vacuum Pressure Swing Adsorption

Pressure swing adsorption (PSA) is a suitable method to enrich the concentration of methane in coal mine methane (CMM) separation processes. However, traditional PSA processes for low-concentration CMM can easily increase the concentration of methane to explosive limits, which subsequently increases the risk of explosion. In this paper, a novel PSA process for low-concentration CMM was studied. using a mixture of activated carbon (AC) and carbon molecular sieve (CMS) as the adsorbent, this method ensures that the gaseous mixture adsorbed does not reach the explosive limits by adsorbing methane and part of the oxygen simultaneously. using a two-bed vacuum PSA experimental apparatus, the low-concentration CMM was safely enriched from 20% to more than 30%, with CMS and AC mass ratio of 3.4. The results of experimental studies indicate that the mixture adsorbent (AC and CMS) has explosion-suppression and flameproof characteristics. The igniting resource (methane) will not explode even if it appears in the adsorbent layer and, in addition, the explosion will not propagate through the adsorbent layer if it happens in other areas

Vacuum Exhaust Process in Pilot-Scale Vacuum Pressure Swing Adsorption for Coal Mine Ventilation Air Methane Enrichment

Recovery and treatment of methane from coal mine ventilation air methane (VAM) with cost-effective technologies have been an ongoing challenge due to low methane concentrations. In this study, a type of coconut shell-based active carbon was employed to enrich VAM with a three-bed vacuum pressure swing adsorption unit. A new vacuum exhaust step for the VPSA process was introduced. The results show that the vacuum exhaust step can increase the methane concentration of the product without changing adsorption and desorption pressure. Under laboratory conditions, the concentration of product increased from 0.4% to 0.69% as the vacuum exhaust ratio increased from 0 to 3.1 when the feed gas concentration was 0.2%. A 500 m³/h pilot-scale test system for VAM enrichment was built rendering good correlation with the laboratory results in terms of the vacuum exhaust step. By using a two-stage three-bed separation unit, the VAM was enriched from 0.2% to over 1.2%

Evaluation Of Rf Capacitance Extraction For Ultrathin Ultraleaky Soi Mos Devices

This letter evaluates a radio-frequency (RF) method to extract the gate capacitance for SOI MOSFETs with ultrathin ultraleaky gate dielectrics. Conventional methods such as two-element and three-element methods using precision impedance analyzer were also compared. The RF method scans the RF capacitance data, assesses its lower and upper limits, and extracts the SOI gate capacitance accurately independent of gate oxide thickness. © 2007 IEEE

3-D Modeling of Gas–Solid Two-Phase Flow in a π-Shaped Centripetal Radial Flow Adsorber

Radial flow adsorber (RFA) is widely used in large-scale pressure swing adsorption (PSA) oxygen production system because of high air separation. In this study, a 3-D modeling of gas–solid two-phase flow was established for the π-shaped centripetal RFA (CP-π RFA). The pressure difference, temperature changes, velocity profiles and oxygen distributions were comparatively studied using this model. Part of the results have been compared with the experiments results, which shows this model can give an accurately prediction. The results show that the pressure and velocity in the adsorber change greatly near the outer hole and central hole, but the overall pressure and velocity changes in the bed are stable. The oxygen product purity in the adsorbent filling area performed better on oxygen enrichment after eight cycles. The oxygen product flow rate will affect the oxygen production performance. The laws of the pressure, velocity, temperature and oxygen distributions can provide an important technical reference for CP-π RFA in the PSA for oxygen production

An unexpectedly stable Y2B5 compound with the fractional stoichiometry under ambient pressure

Boron-rich yttrium borides are an exceptional group of compounds not only with excellent mechanical properties, but also with particular superconducting and thermoelectric properties. Although the Y–B compounds with integral components have been extensively investigated experimentally and theoretically, the yttrium borides with the fractional stoichiometries are rarely observed. Herein, utilizing a combination of the CALYPSO method for crystal structure prediction and first-principles calculations, we made an investigation on a broad range of stoichiometries of yttrium borides. An extraordinary stable Y2B5 compound possessing the fractional stoichiometry with the monoclinic P121/c1 phase is firstly uncovered. Structurally, the P121/c1-Y2B5 crystalline consists of the distorted B6 octahedrons and seven-member B rings. Remarkably, the B–B covalent network following the increment of the boron content in six concerned yttrium borides undergoes an increasing dimension, quasi one-dimensional chain → two-dimensional B ring → a combination of two-dimensional B ring and three-dimensional B6 octahedron → three-dimensional B24 cage. According to a microscopic hardness model, P121/c1–Y2B5 is considered as an incompressible and hard material with the hardness of 18.83 GPa. More importantly, Fm-3 m-YB12 can be classified into an ultra-incompressible material with the appreciable Vickers hardness of 33.16 GPa. The present consequences can provide important insights for understanding the complex crystal structures of boron-rich yttrium borides and stimulate further experimental synthesis of novel multifunctional materials with the fractional compositions

Two-Dimensional Modeling of Pressure Swing Adsorption (PSA) Oxygen Generation with Radial-Flow Adsorber

Radial flow is an important type of flow direction for large-scale pressure swing adsorption (PSA) oxygen generation systems. In this study, a numerical simulation of a PSA oxygen generation process based on radial-flow adsorbers was performed with two-dimensional CFD modeling. The gas distribution, the maldistribution factor and the pressure difference were comparatively investigated at each flow type of the radial-flow adsorber. Considering the gas adsorption performance, the results indicated that the centripetal π-flow radial adsorber has the best flow characteristics for the PSA process. The oxygen purity distribution within the adsorption bed was studied to compare centripetal and centrifugal π-flows, and the former was shown to perform better on oxygen enrichment and adsorbent desorption. The steady state was achieved after eight cycles for the centripetal-π adsorber and each of the four steps of the PSA process was explored in detail to show the advantageous properties for oxygen generation in terms of adsorption and desorption. The relationships between the product flow rate and the oxygen purity and recovery were further investigated