Reverse Depletion Research Articles

CO2 -Fueled Transient Breathing Nanogels that Couple Nonequilibrium Catalytic Polymerization.

Here we present a "breathing" nanogel that is fueled by CO2 gas to perform temporally programmable catalytic polymerization. The nanogel is composed of common frustrated Lewis pair polymers (FLPs). Dynamic CO2 -FLP gas-bridging bonds endow the nanogel with a transient volume contraction, and the resulting proximal effect of bound FLPs unlocks its catalytic capacity toward CO2 . Reverse gas depletion via a CO2 -participated polymerization can induce a reverse nanogel expansion, which shuts down the catalytic activity. Control of external factors (fuel level, temperature or additives) can regulate the breathing period, amplitude and lifecycle, so as to affect the catalytic polymerization. Moreover, editing the nanogel breathing procedure can sequentially evoke the copolymerization of CO2 with different epoxide monomers preloaded therein, which allows to obtain block-tunable copolycarbonates that are unachievable by other methods. This synthetic dissipative system would be function as a prototype of gas-driven nanosynthesizer.

CO2‐Fueled Transient Breathing Nanogels that Couple Nonequilibrium Catalytic Polymerization

AbstractHere we present a “breathing” nanogel that is fueled by CO2 gas to perform temporally programmable catalytic polymerization. The nanogel is composed of common frustrated Lewis pair polymers (FLPs). Dynamic CO2‐FLP gas‐bridging bonds endow the nanogel with a transient volume contraction, and the resulting proximal effect of bound FLPs unlocks its catalytic capacity toward CO2. Reverse gas depletion via a CO2‐participated polymerization can induce a reverse nanogel expansion, which shuts down the catalytic activity. Control of external factors (fuel level, temperature or additives) can regulate the breathing period, amplitude and lifecycle, so as to affect the catalytic polymerization. Moreover, editing the nanogel breathing procedure can sequentially evoke the copolymerization of CO2 with different epoxide monomers preloaded therein, which allows to obtain block‐tunable copolycarbonates that are unachievable by other methods. This synthetic dissipative system would be function as a prototype of gas‐driven nanosynthesizer.

Magneto-tunability of photocurrent in Zn0.3Ni0.7Fe2O4/ZnO-rGO composite heterojunction device

We studied light and magnetic field dependent DC transport properties of Zn0.3Ni0.7Fe2O4/ZnO-reduced graphene oxide composite heterojunction. Current through the heterojunction is expected from the carrier injection and tunneling in forward and reverse bias, respectively. Application of magnetic field has shown both negative magnetoresistance (MR) at forward bias and positive MR at reverse bias. The negative MR is attributed to the reduction of spin dependent scattering in the bulk of Zn0.3Ni0.7Fe2O4 layer. On the other hand, under reverse bias, a magnetic field dependent increase of depletion region in Zn0.3Ni0.7Fe2O4 side is supposed to take place, resulting in a positive MR. Under 660 nm visible light illumination, photoresponse has been observed. Under illumination, negative MR is found in reverse bias. This negative MR is expected to be associated with the magnetic field dependent widening of reverse bias depletion region. In forward bias voltages, under strong illumination of 3.08 mW/cm2 of 660 nm light, a positive MR is found. This positive MR is associated with the light dependent enhancement of depletion width at Zn0.3Ni0.7Fe2O4 side under high injection mode. When the applied voltage is swept along a cycle, irreversible nature of I-V characteristics is observed.

Experimental reaction rates constrain estimates of ozone response to calcium carbonate geoengineering

Stratospheric solar geoengineering (SG) would impact ozone by heterogeneous chemistry. Evaluating these risks and methods to reduce them will require both laboratory and modeling work. Prior model-only work showed that CaCO3 particles would reduce, or even reverse ozone depletion. We reduce uncertainties in ozone response to CaCO3 via experimental determination of uptake coefficients and model evaluation. Specifically, we measure uptake coefficients of HCl and HNO3 on CaCO3 as well as HNO3 and ClONO2 on CaCl2 at stratospheric temperatures using a flow tube setup and a flask experiment that determines cumulative long-term uptake of HCl on CaCO3. We find that particle ageing causes significant decreases in uptake coefficients on CaCO3. We model ozone response incorporating the experimental uptake coefficients in the AER-2D model. With our new empirical reaction model, the global mean ozone column is reduced by up to 3%, whereas the previous work predicted up to 27% increase for the same SG scenario. This result is robust under our experimental uncertainty and many other assumptions. We outline systematic uncertainties that remain and provide three examples of experiments that might further reduce uncertainties of CaCO3 SG. Finally, we highlight the importance of the link between experiments and models in studies of SG.

Initial tests of large format sensors for the ATLAS ITk strip tracker

For the construction of the Inner Tracker (ITk) as part of the phase-II upgrade programme of the ATLAS detector for the High-Luminosity (HL) LHC, batches of Long Strip (LS) and Short Strip (SS) n+-in-p type micro-strip sensors have been produced by Hamamatsu Photonics and Infineon.The full size sensors measure approximately 98 × 98 mm2 and are designed and engineered for tolerance against the 9.7 × 1014 1 MeV neq/cm2 fluence expected at the HL-LHC, including a safety factor of 1.5. Each sensor has 2 or 4 columns of 1280 individual channels arranged at 75.5 μm horizontal pitch.To ensure the sensors comply with their specifications, a Quality Control (QC) procedure has been implemented, comprising measurements on every individual sensor as well as on a sample basis. Every sensor is subjected to an initial visual inspection, after which the full surface of the sensor is captured with very high resolution by an automated camera setup. Non-contact metrology is performed to obtain the sensor surface profile. Electrical measurements establishing the reverse bias leakage current and depletion voltage are then conducted automatically. Sample sensors from every batch are subjected to 40 h of leakage stability checks in controlled atmosphere, and tests on every channel measuring leakage current, coupling capacitance and bias resistance are done. The recorded results are uploaded to a production database following data quality checks.In this paper, QC test validation data and the compiled results for the first batches of production grade sensors are presented. The QC protocol was validated, and the first production sensors were confirmed to be within specification. The results are compared to those from the previous generation of prototype sensors.

Analytical modelling of coal failure in coal seam gas reservoirs in different stress regimes

Coal seam gas (CSG) reservoirs typically have low rock strength. During gas production, pressure depletion and matrix shrinkage may cause the differential stress around the wellbore to exceed the coal mechanical strength and result in rock failure. Coal failure has several detrimental consequences including coal fines production, permeability reduction, wellbore filling and damage to pumps and compressors. The matrix shrinkage causes a unique stress path in CSG reservoirs. However, the details of how matrix shrinkage affects coal failure still have remained uncertain. This paper presents a new workflow to evaluate stress distribution around CSG wells and predicts coal failure by coupling the effects of pressure depletion, matrix shrinkage and wellbore simultaneously. The model calculates Maximum Coal Free Drawdown Pressure (MCFDP) by considering the effects of all contributing parameters and Mogi-Coulomb failure criterion. Data from a vertical well in the San Juan Basin in USA were used to evaluate the validity of the developed model. The developed model was applied to evaluate coal failure under three different stress regimes. The results indicate that pressure depletion and matrix shrinkage have a significant effect on coal failure in all stress regimes. In the case of a normal stress regime, it is found that vertical wellbores are the most stable during the life of a reservoir. However, in the case of strike-slip and reverse stress regimes, pressure depletion and matrix shrinkage could cause the change of stress regime and therefore, the optimum wellbore trajectory could change. Additionally, it is found that in the normal stress regime the depletion and matrix shrinkage reduces the MCFDP of horizontal wellbores more than the vertical wells. However, in the reverse stress regime, depletion and shrinkage cause more reduction of MCFDP in vertical wellbores compared to horizontal wells.

A reverse transcriptase-mediated ribosomal RNA depletion (RTR2D) strategy for the cost-effective construction of RNA sequencing libraries

RNA sequencing (RNA-seq)-based whole transcriptome analysis (WTA) using ever-evolving next-generation sequencing technologies has become a primary tool for coding and/or noncoding transcriptome profiling. As WTA requires RNA-seq data for both coding and noncoding RNAs, one key step for obtaining high-quality RNA-seq data is to remove ribosomal RNAs, which can be accomplished by using various commercial kits. Nonetheless, an ideal rRNA removal method should be efficient, user-friendly and cost-effective so it can be adapted for homemade RNA-seq library construction. Here, we developed a novel reverse transcriptase-mediated ribosomal RNA depletion (RTR2D) method. We demonstrated that RTR2D was simple and efficient, and depleted human or mouse rRNAs with high specificity without affecting coding and noncoding transcripts. RNA-seq data analysis indicated that RTR2D yielded highly correlative transcriptome landscape with that of NEBNext rRNA Depletion Kit at both mRNA and lncRNA levels. In a proof-of-principle study, we found that RNA-seq dataset from RTR2D-depleted rRNA samples identified more differentially expressed mRNAs and lncRNAs regulated by Nutlin3A in human osteosarcoma cells than that from NEBNext rRNA Depletion samples, suggesting that RTR2D may have lower off-target depletion of non-rRNA transcripts. Collectively, our results have demonstrated that the RTR2D methodology should be a valuable tool for rRNA depletion.

Human telomerase reverse transcriptase depletion potentiates the growth-inhibitory activity of imatinib in chronic myeloid leukemia stem cells.

Although tyrosine kinase inhibitors (TKIs) revolutionized the management of chronic myeloid leukemia (CML), resistance against TKIs and leukemia stem cell (LSC) persistence remain a clinical concern. Therefore, new therapeutic strategies combining conventional and novel therapies are urgently needed. Since telomerase is involved in oncogenesis and tumor progression but is silent in most human normal somatic cells, it may be an interesting target for CML therapy by selectively targeting cancer cells while minimizing effects on normal cells. Here, we report that hTERT expression is associated with CML disease progression. We also provide evidence that hTERT-deficient K-562cells do not display telomere shortening and that telomere length is maintained through the ALT pathway. Furthermore, we show that hTERT depletion exerts a growth-inhibitory effect in K-562cells and potentiates imatinib through alteration of cell cycle progression leading to a senescence-like phenotype. Finally, we demonstrate that hTERT depletion potentiates the imatinib-induced reduction of the ALDH+-LSC population. Altogether, our results suggest that the combination of telomerase and TKI should be considered as an attractive strategy to treat CML patients to eradicate cancer cells and prevent relapse by targeting LSCs.

Evaluation of water shortage crisis in the Middle East and possible remedies

AbstractWater resources in the Middle East region are becoming scarce, while millions of people already do not have access to adequate water for drinking and sanitary purposes. Water resources depletion has become a significant problem in this region that is likely to worsen. Current research by remote sensing analysis indicates a descending trend of water storage in the Middle East region, where agriculture plays a crucial role in socio-economic life. This study introduces an approach quantifying water depletion in the Middle Eastern countries, which are being challenged in the management of their water resources. Furthermore, this paper presents results of a survey assessing the status of water use and supply in Middle Eastern countries and outlines some potential remedies. Specifically, Iran's water use is evaluated and compared with its neighbors'. The water equivalent anomaly (WEA) and total water storage (TWS) depletion are two indexes of water scarcity calculated for Middle Eastern countries surveyed herein. Our analysis reveals that Lebanon, Syria, Iraq, and Iran are countries with very negative water scarcity indexes. These estimates prove that international cooperation is needed to manage available regional water resources and reverse depletion of natural water sources. It is demonstrated herein that virtual water trade can help remediate regional water shortage in Middle Eastern countries.

Role of Participatory Forest Management in Woody Species Diversity and Forest Conservation: The Case of Gimbo Woreda in Keffa Zone South West Ethiopia

Participatory forest management was started more than one decade ago in Ethiopia as one of the ways applied to reverse deforestation and depletion of natural resources. However, there are no adequate site specific empirical and quantitative studies on the effectiveness of PFM approaches in conservation of woody species diversity and forest conservation. Therefore, this study was designed to assess the impacts of PFM on woody species diversity in selected forest user groups in Gimbo Woreda, South West Ethiopia. Vegetation data were collected from different PFM user groups and adjacent Non-PFM forest blocks. A total of 63 plots measuring 20 m × 20 m were employed to collect species composition and structural data. Data for all the sapling and seedlings were also collected within subplots of 5 m X 5 m and 2 m X 2 m respectively. Accordingly a total of 73 different woody plant species (72 at PFM and 54 at Non-PFM blocks), representing 64 genera and 35 families were recorded, with 53 species shared. Woody species diversity and evenness were higher in the forest with PFM (H´ = 3.04, E = 0.76) compared to the forest without PFM (H´ = 2.8, E =0 .70). The overall average values of sapling and seedling density were also significantly (p < .05) higher in PFM than Non-PFM forests. However, no significant variations were observed in basal area and dominance of the species between the two forest blocks. Thus it can be concluded that participatory forest management is showing signs of delivering impact in terms of woody species diversity conservation in the study area. However, there is a gap in some of forest user groups in terms of forest protection from an illegal activities. Therefore it is important to conduct further assessments in the remaining forest user group’s to have baseline data for further study and performance evaluation over all forests under PFM approaches. Keywords : Forest User Group, Regeneration, Species diversity, Human induced disturbance. DOI : 10.7176/JEES/9-6-01 Publication date :June 30 th 2019

DIFFERENTIAL DEPLETION CAPACITANCE APPROXIMATION ANALYSIS UNDER DC VOLTAGE FOR AIR-EXPOSED Cu/n-Si SCHOTTKY DIODES

It is well known that the semiconductor surface is easily oxidized by air-media in time. This work studieds the characterization of Schottky diodes and changes in depletion capacitance, which is caused by air exposure of a group of Cu/n-Si/Al Schottky diodes. First, data for current-voltage and capacitance-voltage were a Ren, and then ideality factor, barrier height, built-in potential ([Formula: see text], donor concentration and Fermi level, interfacial oxide thickness, interface state density were calculated. It is seen that depletion capacitance was calculate; whereafter built-in potential played an important role in Schottky diodes characteristic. Built-in potential directly affects the characteristic of Schottky diodes and a turning point occurs. In case of forward and reverse bias, depletion capacitance versus voltage graphics are matched, but in an opposite direction. In case of forward bias, differential depletion capacitance begins from minus values, it is raised to first [Formula: see text], then reduced to second [Formula: see text] under the minus condition. And it sharply gones up to positive apex, then sharply falls down to near zero, but it takes positive values depending on DC voltage. In case of reverse bias, differential depletion capacitance takes to small positive values. In other respects, we see that depletion characteristics change considerably under DC voltage.

A reconfigurable silicon-on-insulator diode with tunable electrostatic doping

P-N diodes can be emulated in ultrathin, fully depleted Silicon-On-Insulator films by appropriately biasing the front and back gates. Adjacent electron and hole populations form a virtual P-N junction. Systematic current-voltage I-V characteristics are presented revealing similarities and major differences with those of conventional P-N diodes with ion-implanted doping. The lateral electric field from the anode combines with the gate-induced vertical field and leads to unusual two-dimensional effects. A distinct merit of the virtual diode is the possibility to adjust the concentrations of electrostatic doping via the gates. The reverse current, forward current, and depletion depth become gate-controlled. Our experiments show that by modifying the type, N or P, of electrostatic doping, the virtual diode can be reconfigured in 8 other devices: semi-virtual diodes, PIN diodes, tunneling field-effect transistors or band-modulation FET.

Reverse depletion effects and the determination of ligand density on some spherical bioparticles

In cell environments crowded with macromolecules, the depletion effects act and assist in the assembly of a wide range of cellular structures, from the cytoskeleton to the chromatin loop, which are well accepted. But a recent quantum dot experiment indicated that the dimensions of the receptor–ligand complex have strong effects on the size-dependent exclusion of proteins in cell environments. In this article, a continuum elastic model is constructed to resolve the competition between the dimension of the receptor–ligand complex and depletion effects in the endocytosis of a spherical virus-like bioparticle. Our results show that the depletion effects do not always assist endocytosis of a spherical virus-like bioparticle; while the dimension of the ligand–receptor complex is larger than the size of a small bioparticle in cell environments, the depletion effects do not work and reverse effects appear. The ligand density covered on the virus can be identified quantitatively.

The Electrical Characteristics of ZnO :Ga/p-Si Junction Diode

ABSTRACTThe junction characteristics between ZnO:Ga (GZO) film and p-Si substrate are discussed in the research. For the transparent semiconductor ZnO, the element Ga is chosen to be the dopant source to produce a high quality n-type ZnO thin film. The ZnO:Ga (GZO) film shows a average transmittance is 84.7% (above 400 nm), a bandgap energy of 3.37 eV, a carrier concentration of 7.29×1013 cm−3and a resistivity of 118 Ω-cm. For the GZO/p-Si junction, it shows a junction barrier height of 0.54 eV with an ideality factor of 1.24. The capacitance-voltage measurement shows that it has a uniform reverse bias depletion layer. The Cheung function is also brought to discussion the diode characteristics.

Piezoelectric Potential Gated Field-Effect Transistor Based on a Free-Standing ZnO Wire

We report an external force triggered field-effect transistor based on a free-standing piezoelectric fine wire (PFW). The device consists of an Ag source electrode and an Au drain electrode at two ends of a ZnO PFW, which were separated by an insulating polydimethylsiloxane (PDMS) thin layer. The working principle of the sensor is proposed based on the piezoelectric potential gating effect. Once subjected to a mechanical impact, the bent ZnO PFW cantilever creates a piezoelectric potential distribution across it width at its root and simultaneously produces a local reverse depletion layer with much higher donor concentration than normal, which can dramatically change the current flowing from the source electrode to drain electrode when the device is under a fixed voltage bias. Due to the free-standing structure of the sensor device, it has a prompt response time less than 20 ms and quite high and stable sensitivity of 2%/microN. The effect from contact resistance has been ruled out.

Tumor necrosis factor alpha and macrophages in the brain of herpes simplex virus type 1–infected BALB/c mice

After uniocular anterior chamber (AC) inoculation of herpes simplex virus type 1 (HSV-1), virus and TNF alpha (TNF-alpha) are detected in the suprachiasmatic nuclei (SCN). The goal of this study was to investigate the role of TNF-alpha and macrophages in the brain of HSV-1-infected BALB/c mice. Mice were treated with thalidomide for TNF-alpha inhibition or injected with clodronate liposomes to deplete macrophages, and the AC of one eye (ipsilateral) was injected with HSV-1 (KOS). The location of HSV-1, macrophages, and TNF-alpha was determined by fluorescence immunohistochemistry and the titer of virus was determined by plaque assay. Inhibition of TNF-alpha was determined by reverse transcriptase-polymerase chain reaction (RT-PCR) and depletion of macrophages was assessed by flow cytometry. In thalidomide-treated mice, TNF-alpha RNA levels were reduced in the SCN. Both SCN were infected by day 5 post inoculation (p.i.) and the titer of virus in the SCN contralateral to the side of injection was increased. The number of splenic macrophages was significantly reduced in clodronate-treated mice compared with controls. In macrophage-depleted mice, both SCN were infected at day 6 p.i. and the titer of virus in the SCN of these mice was increased at days 6 and 7 p.i. compared with controls. The titer of virus in the contralateral (uninoculated) eye of macrophage-depleted mice was increased at day 7 p.i. Fewer F4/80+ cells were observed in the SCN of macrophage-depleted mice. The results of these studies suggest that TNF-alpha plays a role in limiting virus replication in the SCN of euthymic BALB/c mice and that one source of TNF-alpha is macrophages.

Radiation damage in silicon detectors

Radiation damage effects in silicon detectors under severe hadron and gamma-irradiation are surveyed, focusing on bulk effects. Both macroscopic detector properties (reverse current, depletion voltage and charge collection) as also the underlying microscopic defect generation are covered. Basic results are taken from the work done in the CERN-RD48 (ROSE) collaboration updated by results of recent work. Preliminary studies on the use of dimerized float zone and Czochralski silicon as detector material show possible benefits. An essential progress in the understanding of the radiation-induced detector deterioration had recently been achieved in gamma irradiation, directly correlating defect analysis data with the macroscopic detector performance.

Diagenetic constraints on the use of cerium anomalies as palaeoseawater redox proxies: an isotopic and REE study of Cambrian phosphorites

Seawater rare-earth element (REE) distributions show heavy REE enrichment and cerium depletion but these characteristics are only rarely found in ancient, marine authigenic minerals such as carbonate fluorapatite and calcite. This enigma may be due to changing REE distributions in seawater through time or to post-depositional redistribution of REE. Differentiating between these two factors is, however, far from straightforward as their relative importance is likely to vary and evidence is often ambiguous. In this article, we present REE as well as strontium and sulphur isotope data for basal Cambrian phosphorites of South China, which confirm the emerging rule of thumb that granular phosphorites seldom reveal extreme departures from the seawater norm, and tend to undergo, therefore, less diagenetic alteration of REE spectra than skeletal apatites and other phosphate-types. This study reveals stratigraphic trends in Ce anomalies (Ce/Ce*) that could be taken to imply the preservation of a palaeoenvironmental signal. However, further investigation of our data shows that such trends in phosphorites can also be caused by post-depositional alteration, which tends to (1) increase REE contents, (2) reverse Ce depletion, (3) alter Eu anomalies, and (4) concentrate preferentially the middle REE (MREE). Further alteration, which may be due to weathering, has led to HREE depletion, and positive La and Y anomalies (tetrad effect). This is the first study where Ce anom. and phosphate-bound sulphate S-isotope values could be compared for one particular stratigraphic section, which provides us with an additional tool for the interpretation of diagenetic redox conditions. Least altered phosphorites from Meishucun that yield a strongly negative Ce anom. constrain early Cambrian seawater δ 34S to about +33‰. We conclude that phosphorite Ce anom. primarily records variations in the local conditions of diagenesis, while outlining some special cases in which diagenetic redox conditions may broadly reflect local bottom-water redox conditions.

In vitro antioxidant neuroprotective activity of BN 80933, a dual inhibitor of neuronal nitric oxide synthase and lipid peroxidation.

BN 80933, a dual inhibitor of neuronal nitric oxide synthase and lipid peroxidation, prevents in vivo brain ischemic/reperfusion injury. In the present study, BN 80933 was shown to protect neurons from hypoxia-induced cell death in primary cultures of cortical neurons. BN 80933 prevented lactate dehydrogenase activity elevation induced by hypoxia, displaying an IC50 value of 0.15 +/- 0.05 microM. This effect was likely due to the antioxidant properties of BN 80933 because Trolox, but not NG-nitro-L-arginine, also elicited protection. The antioxidant property of BN 80933 was then further investigated on HT-22 cells subjected to buthionine sulfoximine- or glutamate-induced glutathione depletion. The relative order of potency of the various compounds to inhibit oxidative stress-induced neuronal death (BN 80933 > U104067 > butylated hydroxytoluene > 17beta-estradiol > Trolox > vitamin E) correlated with their ability to inhibit brain membrane lipid peroxidation (correlation coefficient = 0.939). BN 80933 afforded protection even when added 6 h after glutamate exposure. BN 80933 did not reverse intracellular glutathione depletion but prevented elevation of the level of beta-epiprostaglandin F2alpha (8-isoprostane), which appeared to be a delayed phenomenon. In conclusion, BN 80933 induces a potent cytoprotection that may be mediated by inhibition of delayed lipid peroxidation.

Characterization of neutron irradiated silicon microstrip detectors

The radiation hardness of silicon microstrip detectors has been investigated on full-size prototypes similar to the ones that will be installed in the forward tracker of CMS, where a very intense radiation environment is envisaged. Silicon detectors were exposed to a neutron beam with 3 different fluences up to 2.4 × 10 14 neutrons/cm 2, more than those foreseen at LHC after 10 years of operation. Degradation effects of the device properties regarding reverse current, depletion voltage, bulk and interstrip capacitance has been measured in laboratory as function of bias voltage, temperature and neutron fluence.