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Background/aims: Bile reflux (BR) can influence the gastric environment by altering gastric acidity and possibly the gastric microbiota composition. This study investigated the correlation between bile acids and microbial compositions in the gastric juice of 50 subjects with differing gastric pathologies. Methods: This study included 50 subjects, which were categorized into three groups based on the endoscopic BR grading system. The primary and secondary bile acid concentrations in gastric juice samples were measured, and microbiota profiling was conducted using 16 S rRNA gene sequencing. Results: Significant differences were observed in each bile acid level in the three endoscopic BR groups (P < 0.05). The Shannon index demonstrated a significant decrease in the higher BR groups (P < 0.05). Analysis of the β-diversity revealed that BR significantly altered the gastric microbiota composition. The presence of neoplastic lesions and the presence of H. pylori infection impacted the β-diversity of the gastric juice microbiota. The abundance of the Streptococcus and Lancefielfdella genera exhibited positive correlations for almost all bile acid components(P < 0.05). In addition, the abundance of Slobacterium, Veillonella, and Schaalia showed positive correlations with primary unconjugated bile acids (P < 0.05). Conclusion: Changes in microbial diversity in the gastric juice were associated with BR presence in the stomach. This result suggests that the degree of BR should be considered when studying the gastric juice microbiome. [ABSTRACT FROM AUTHOR]

In this study, the static and kinetic friction coefficients and their effect on the noise generation were investigated by preparing the coating agent using polyurethane resin, polysiloxane, ethylene and propylene oxide (EO/PO)-modified polysiloxane, PP wax, carbon black, and SiO2. The difference between the static and kinetic friction coefficients decreased with the fraction of (EO/PO)-modified polysiloxane while sharply increasing with the friction velocity. The differences in these friction characteristics reduced the magnitude of noise generation, and the matting property was also increased by the addition of PP wax. [ABSTRACT FROM AUTHOR]

Thyrotropin-releasing hormone (TRH) acts centrally to exert pleiotropic actions independently from its endocrine function, including antinociceptive effects against somatic pain in rodents. Whether exogenous or endogenous activation of TRH signaling in the brain modulates visceral pain is unknown. Adult male Sprague-Dawley rats received an intracerebroventricular (ICV) injection of the stable TRH analog, RX-77368 (10, 30 and 100 ng/rat) or saline (5 µl) or were semi-restrained and exposed to cold (4°C) for 45 min. The visceromotor response (VMR) to graded phasic colorectal distensions (CRD) was monitored using non-invasive intracolonic pressure manometry. Naloxone (1 mg/kg) was injected subcutaneously 10 min before ICV RX-77368 or saline. Fecal pellet output was monitored for 1 h after ICV injection. RX-77368 ICV (10, 30 and 100 ng/rat) reduced significantly the VMR by 56.7%, 67.1% and 81.1% at 40 mmHg and by 30.3%, 58.9% and 87.4% at 60 mmHg respectively vs ICV saline. Naloxone reduced RX-77368 (30 and 100 ng, ICV) analgesic response by 51% and 28% at 40 mmHg and by 30% and 33% at 60 mmHg respectively, but had no effect per se. The visceral analgesia was mimicked by the acute exposure to cold. At the doses of 30 and 100 ng, ICV RX-77368 induced defecation within 30 min. These data established the antinociceptive action of RX-77368 injected ICV in a model of visceral pain induced by colonic distension through recruitment of both opioid and non-opioid dependent mechanisms. • ICV TRH agonist, RX-77368 inhibits the visceromotor response to colorectal distension in rats. • ICV RX-77368 analgesic action recruits opioid-dependent and independent pathways. • Endogenous brain TRH released by acute cold exposure mimics ICV RX-77368. [ABSTRACT FROM AUTHOR]

We theoretically investigate and discuss an electrically tunable terahertz filter design and its optical switching properties based on the defect mode of a woodpile metallic photonic crystal (MPC). The model filter design is based on a dual use of an MPC as a resonator and as electrodes with a liquid crystal used as a defect layer. The static and the dynamic responses of a realistic liquid crystal are obtained using the Oseen-Frank elastic continuum theory, and the corresponding transmission spectra are calculated using an analytic modal expansion method combined with a transfer-matrix method. The tuning range of f = 1.430∼1.577 THz and the order of milliseconds switching property are observed in our design. [ABSTRACT FROM AUTHOR]

We investigate a photon recycling scheme using two-dimensional metallic photonic crystals made of silver to improve the energy efficiency of an incandescent light source. A theoretical framework is presented to analyze the resultant photon-recycled lighting system. Calculation results show that the system can reach a maximum luminous efficiency of 125 lm/W, which is 8 times higher than that of a bare blackbody radiation at 2800 K. The color temperature of the system is calculated to be around 3500 K or below, while the color rendering index is between 68 and 90. These results suggest that a photon-recycled incandescent light source using metallic photonic crystals can be a viable alternative future lighting solution. [ABSTRACT FROM AUTHOR]

Polyurethane- and polysiloxane-based coating agents are widely used in automobiles and electronic devices for sealing. To study a component which affects their surface properties, polyurethane resins (PUR) were synthesized from polyester polyol, perfluoropolyether (PFPE) diol, and toluene diisocyanate. The coating agents were subsequently prepared by adding various amounts of PE wax, carbon black, matting agents, and silicone resin. The effects of the soft and hydrophobic PFPE diol content in the coating agent on the surface properties, such as hydrophobicity, noise generation, and friction coefficient were investigated. Although the bulk content of PFPE diol in polyols is 1.7 wt% or less, hydrophobicity, workability, friction coefficient, and noise generation of the newly designed PUR coating agents were improved while their tensile strength and abrasion resistance decreased. These results indicate that the PFPE diol chains in the modified PURs are segregated at the surface layer and affected surface properties as well as bulk properties. [ABSTRACT FROM AUTHOR]

The TARDBP gene variant is a known major cause of amyotrophic lateral sclerosis (ALS), with limited reports of Korean patients with ALS harboring the variants in TARDBP. This large cohort study introduces four ALS patients who share the p.M337V variant of the TARDBP, allowing for an investigation of clinical characteristics and prognosis by analyzing previously reported cases with the same variant. From November 2014 to August 2022, participants were recruited from two tertiary hospitals in Seoul, Korea. Clinical characteristics of patients diagnosed with ALS carrying the variant in TARDBP were evaluated. Previous articles demonstrating subjects' characteristics were reviewed. Four patients were identified with the pathogenic missense variant (c.1009A>G; p.M337V) in the TARDBP. The mean age of onset was 55 years old, and none of the patients showed severe cognitive impairment. Sixty-three patients carrying the p.M337V variant in TARDBP from this study and previous reports delineated young age of onset (51.6 years), high frequency of bulbar onset patients (61.9%), and low comorbidity of frontotemporal dementia. This study reveals the presence of pathogenic variant of TARDBP in Korea and emphasizes the importance of genetic screening of the TARDBP gene, in diagnosing ALS and evaluating prognosis among familial and simplex ALS patients in Korea. [ABSTRACT FROM AUTHOR]

Although polyurethane (PU)- and polysiloxane-based coating agents find wide applications in electronics and automotive industries (e.g., for sealing), their full potential can be realized only based on a deep understanding of property-determining factors. To contribute to this understanding, we synthesized PU resins from polycarbonate diol, poly(tetramethylene glycol), and 4,4-diphenylmethane diisocyanate. The abrasion resistance, modulus, and tensile strength of PU films increased with increasing hard segment content whereas the elongation at break of these films concomitantly decreased. PU-based coating agents were prepared by adding PE wax and other modifiers and their friction coefficients were investigated. A friction coefficient of coating agent was strongly affected by particle size and content of PE waxes. [ABSTRACT FROM AUTHOR]

We investigate lattice thermal conductivities of Si nanowires (SiNWs) based on classical nonequilibrium molecular dynamics (NEMD) simulations. The SiNWs are supposed to have a crystalline diamond structure and extend along the [001] axial direction with the {100} sidewall facets on which the surface Si atoms are all dimerized and fully passivated by hydrogen. Various sizes in the square cross section are considered, and the lengths are varied to find the diffusive limits of the lattice thermal conductivities. The upper limits of the diffusive lattice thermal conductivities of SiNWs are 11.2, 16.0, 22.8, and 28.0 W/mK for SiNWs with widths of 2.7, 4.9, 8.1, and 11.3 nm, respectively. The mode-averaged mean free paths of phonons are 50, 52, 63, and 80 nm for the SiNWs, respectively, which are 7–19 times longer than the SiNW widths. [ABSTRACT FROM PUBLISHER]

Methanogenic Archaea are of importance at the end of the anaerobic digestion (AD) chain for biomass conversion. They finally produce methane, the end-product of AD. Among this group of microorganisms, members of the genus Methanobacterium are ubiquitously present in anaerobic habitats, such as bioreactors. The genome of a novel methanogenic archaeon, namely Methanobacterium congolense Buetzberg, originally isolated from a mesophilic biogas plant, was completely sequenced to analyze putative adaptive genome features conferring competitiveness of this isolate within the biogas reactor environment. Sequencing and assembly of the M. congolense Buetzberg genome yielded a chromosome with a size of 2,451,457 bp and a mean GC-content of 38.51%. Additionally, a plasmid with a size of 18,118 bp, featuring a GC content of 36.05% was identified. The M. congolense Buetzberg plasmid showed no sequence similarities with the plasmids described previously suggesting that it represents a new plasmid type. Analysis of the M. congolense Buetzberg chromosome architecture revealed a high collinearity with the Methanobacterium paludis chromosome. Furthermore, annotation of the genome and functional predictions disclosed several genes involved in cell wall and membrane biogenesis. Compilation of specific genes among Methanobacterium strains originating from AD environments revealed 474 genetic determinants that could be crucial for adaptation of these strains to specific conditions prevailing in AD habitats. [ABSTRACT FROM AUTHOR]

A new highly selective and sensitive chemosensor 1 for both Al 3+ and F − was designed and synthesized. 1 could detect both Al 3+ and F − with turn-on fluorescence behavior in a nearly perfect aqueous solution. The binding stoichiometry of receptor 1 with Al 3+ and F − was proposed to be 1:1, respectively, based on Job plot, 1 H NMR titration and ESI-mass spectrometry analysis. The detection limits (1.12 μM for Al 3+ and 7.01 μM for F − ) of 1 for Al 3+ and F − were lower than the World Health Organization guidelines (7.41 μM for Al 3+ and 79 μM for F − ) for drinking water. Chemosensor 1 was also successfully applied to living cells for simultaneous detection and quantification of both Al 3+ and F − . Moreover, the sensing mechanisms of 1 toward Al 3+ and F − were explained by theoretical calculations. [ABSTRACT FROM AUTHOR]

A simple fluorescent chemosensor 1 for the detection of Hg2+ and pH was developed by a combination of 2-aminoethyl piperazine and 4-chloro-7-nitrobenz-2-oxa-1,3-diazole. The sensor 1 showed OFF–ON behavior for different colors of fluorescence in the presence of Hg2+ and under acidic conditions, respectively, in a near-perfect aqueous solution. The turn-on fluorescence caused by inhibition of photoinduced electron transfer was explained by theoretical calculations. 1 could be used to quantify Hg2+ in water samples, and its in vitro studies with HeLa cells showed fluorescence in the presence of Hg2+. In addition, 1 could selectively detect S2− by changing its color from orange to pink in a near-perfect aqueous solution. Moreover, 1 could be used as a practical, visible test kit for S2−. [ABSTRACT FROM AUTHOR]

Using electron paramagnetic resonance and density functional theory calculations, we show that the shallow donor responsible for the n-type conductivity in natural MoS2 is rhenium (Re) with a typical concentration in the low 1017 cm-3 range and the g -values: g|| = 2.0274 and g⊥ = 2.2642. In bulk MoS2, the valley-orbit (VO) splitting and ionization energy of the Re shallow donor are determined to be ~3 meV and ~27 meV, respectively. Calculations show that the VO splitting of Re approaches the value in bulk if the number of MoS2 layers is larger than four and increases to 97.9 meV in a monolayer. [ABSTRACT FROM AUTHOR]

Detection of protein phosphorylation at a specific residue has been achieved by using antibodies, which have usually been raised by animal immunization. However, there have been no reports of the humanization of phosphospecific non-human antibodies. Here, we report the humanization of a chicken pT231 antibody specific to a tau protein-derived peptide carrying the phosphorylated threonine at residue 231 (pT231 peptide) as a model for better understanding the phosphoepitope recognition mechanism. In the chicken antibody, the phosphate group of the pT231-peptide antigen is exclusively recognized by complementarity determining region 2 of the heavy chain variable domain (VH-CDR2). Simple grafting of six CDRs of the chicken antibody into a homologous human framework (FR) template resulted in the complete loss of pT231-peptide binding. Using a yeast surface-displayed combinatorial library with permutations of 11 FR residues potentially affecting CDR loop conformations, we identified 5 critical FR residues. The back mutation of these residues to the corresponding chicken residues completely recovered the pT231-peptide binding affinity and specificity of the humanized antibody. Importantly, the back mutation of the FR 76 residue of VH (H76) (Asn to Ser) was critical in preserving the pT231-binding motif conformation via allosteric regulation of ArgH71, which closely interacts with ThrH52 and SerH52a residues on VH-CDR2 to induce the unique phosphate-binding bowl-like conformation. Our humanization approach of CDR grafting plus permutations of FR residues by combinatorial library screening can be applied to other animal antibodies containing unique binding motifs on CDRs specific to posttranslationally modified epitopes. [ABSTRACT FROM AUTHOR]

There are several methods available in measuring food taste. The sensory evaluation, for instance, is a typical method for panels to test of taste and recognize smell with their nose by measuring the degree of taste characteristic, intensity, and pleasure. There are many issues entailed in the traditional sensory evaluation method such as forming a panel and evaluation cost; moreover, it is only localized in particular areas. Accordingly, this paper aimed to select food in one particular area, and compare and review the content between sensory evaluations using a taste biological sensor, as well as presenting an analysis of brainwaves using EEG and finally a proposal of a new method for sensory evaluation. In this paper, the researchers have conducted a sensory evaluation whereas a maximum of nine points were accumulated by purchasing eight types of rice wine. These eight types of Makgeolli were generalized by generating multidimensional data with the use of TS-5000z, thus learning mapping points and scaling them. The contribution of this paper, therefore, is to overcome the disadvantages of the sensory evaluation with the usage of the suggested taste biological sensor system. [ABSTRACT FROM AUTHOR]

Monitoring of methanogenic communities in anaerobic digesters using molecular-based methods is very attractive but can be cost-intensive. A new and fast quantification method by microscopic image analysis was developed to accompany molecular-based methods. This digitalized method, called quantitative microscopic fingerprinting ( QMF), enables quantification of active methanogenic cells (N mL−1) by their characteristic auto-fluorescence based on coenzyme F420. QMF was applied to analyze the methanogenic communities in three biogas plant samples, and the results were compared with the relative proportion of gene copy numbers obtained with the quantitative PCR (q PCR). Analysis of QMF demonstrated dominance of Methanomicrobiales and Methanobacteriales in relation to the total methanogenic community in digesters operating at high ammonia concentrations, which corresponded to the results established by q PCR. Absolute microbial counts by QMF and the numbers obtained by q PCR were not always comparable. On the other hand, the restricted morphological analysis by QMF was enhanced by the capability of q PCR to identify microbes. Consequently, dual investigations of both methods are proposed to improve monitoring of anaerobic digesters. For a rough estimation of the methanogenic composition in anaerobic digesters, the QMF method seems to be a promising approach for the rapid detection of microbial changes. [ABSTRACT FROM AUTHOR]

Abstract: As a non-immunoglobulin protein scaffold, human kringle domain (KD) has attractive properties such as high specificity, stability, and production in bacterial hosts. Here, we developed a rapid and sensitive fluorescence-linked immunosorbent assay (FLISA) system using a fluorescent kringle domain (fluoKD), a fusion protein of a green fluorescent protein (GFP), and a kringle domain variant (KD548). Two kinds of fluoKDs in which KD was fused to the N terminus of GFP (N-fluoKD) or the C terminus of GFP (C-fluoKD) were constructed and characterized. In Escherichia coli host, both fluoKDs were produced in high yield and solubility and were successfully purified by a simple procedure. The purified fluoKDs exhibited strong fluorescent activities and high affinities to the target antigen. Furthermore, it was successfully demonstrated that the FLISA with purified fluoKDs allowed for more rapid detection of target antigens with higher sensitivity compared with conventional enzyme-linked immunosorbent assay (ELISA), indicating that a simple, rapid, and sensitive immunoassay system could be developed by using KD instead of antibody or antibody fragments. [Copyright &y& Elsevier]

Background: This study aimed to identify the differences in the psychological characteristics of the anatomical location of functional gastrointestinal disorders (FGIDs) and the factors that influence the quality of life (QOL). Methods: Altogether, 233 patients with FGIDs were classified into the upper gastrointestinal disorder (UGID; n = 175) group and the lower gastrointestinal disorder group (LGID; n = 58). Psychological characteristics and QOL were evaluated using the validated questionnaires. Results: The LGID group demonstrated higher scores in 'emotional depression' than the UGID group in depressive symptoms (t = −3.031, p < 0.01). A significant difference was observed between groups in 'significant others' in social supports (t = 2.254, p < 0.05). Significant differences were observed between the groups in hardiness (t = 2.259, p < 0.05) and persistence (t = 2.526, p < 0.05) in resilience, while the LGID group demonstrated significantly lower scores than the UGID group in 'negative affectivity' in type-D personality (t = −1.997, p < 0.05). Additionally, the LGID group demonstrated lower QOL than the UGID group (t = 2.615, p < 0.05). The stepwise regression analysis on QOL involved depression, resilience, social support, and childhood trauma, which accounted for 48.4% of the total QOL explanatory variance. Conclusions: Psychological characteristics and QOL significantly differed when FGIDs were classified according to anatomical location. Thus, psychological interventions customized for each type of FGIDs may be necessary for effective treatment. [ABSTRACT FROM AUTHOR]

Immunotoxins (ITs), which are toxin-fused tumor antigen-specific antibody chimeric proteins, have been developed to selectively kill targeted cancer cells. The epidermal growth factor receptor (EGFR) is an attractive target for the development of anti-EGFR ITs against solid tumors due to its overexpression on the cell surface of various solid tumors. However, the low basal level expression of EGFR in normal tissue cells can cause undesirable on-target/off-tumor toxicity and reduce the therapeutic window of anti-EGFR ITs. Here, based on an anti-EGFR monobody with cross-reactivity to both human and murine EGFR, we developed a strategy to tailor the anti-EGFR affinity of the monobody-based ITs carrying a 24-kDa fragment of Pseudomonas exotoxin A (PE24), termed ER-PE24, to distinguish tumors that overexpress EGFR from normal tissues. Five variants of ER-PE24 were generated with different EGFR affinities (KD ≈ 0.24 nM to 104 nM), showing comparable binding activity for both human and murine EGFR. ER/0.2-PE24 with the highest affinity (KD ≈ 0.24 nM) exhibited a narrow therapeutic window of 19 pM to 93 pM, whereas ER/21-PE24 with an intermediate affinity (KD ≈ 21 nM) showed a much broader therapeutic window of 73 pM to 1.5 nM in in vitro cytotoxic assays using tumor model cell lines. In EGFR-overexpressing tumor xenograft mouse models, the maximum tolerated dose (MTD) of intravenous injection of ER/21-PE24 was found to be 0.4 mg/kg, which was fourfold higher than the MTD (0.1 mg/kg) of ER/0.2-PE24. Our study provides a strategy for the development of IT targeting tumor overexpressed antigens with basal expression in broad normal tissues by tailoring tumor antigen affinities. [ABSTRACT FROM AUTHOR]

The excited holes occupying the valence band tail (VBT) states in amorphous oxide semiconductors (AOS) are found to induce formation of meta-stable ${\rm O}_{2}^{{\rm 2}- } $ peroxide defects. The VBT states are at least partly characterized by the O-O ppσ* molecular orbital, and the localized-hole-mediated lattice instability results in the formation of the peroxide defects. Along with the O-O bond formation, the ppσ* state is heightened up into the conduction bands, and two electrons are accordingly doped in the electronic ground state. The energy barrier from the ${\rm O}_{2}^{{\rm 2}- } $ peroxide state to the normal disorder state is found to be 0.97 eV in hybrid density functional theory. The hole-mediated formation of the meta-stable peroxide defects and their meta-stability is suggested as an origin of the negative bias and/or illumination stress instability in AOS. [ABSTRACT FROM AUTHOR]

Abstract: To date, there are about 49 biogas plants in South Korea that are generally recognized as economically and technically unsuccessful due to lack of knowhow, deficient technologies and policies. There is a need to analyze the status of biogas technology and policy in South Korea from the point of view of an external biogas expert, since biogas technology in South Korea has not yet been analyzed by foreign biogas experts so far. For analyzing site investigation, literature research and interviews are performed. It was found that there are several lacks of conceptual design of biogas technology, such as plant dimension, energy balance, operation knowhow. Technical and financial support for the development of biogas technology was insufficient so far. There are some policies to support biogas technologies, however financial support from different ministries seemed not to have been used efficiently. Some policies are planned excessively so that they cannot be realized on time. Based on the general policy called “Green Growth”, the Korean government plans to establish a biogas market in South Korea in order to recover energy from organic waste. For this purpose, R&D efforts should be intensified for consulting and education in national and international networks for the transfer of knowhow and technologies. Definition of the existing restrictions on the development of biogas technology is required. By developing a biogas roadmap, the creation of a biogas market could be promoted efficiently in South Korea. [Copyright &y& Elsevier]

Abstract: The aim of this study is to analyze the relationship among groundwater productivity data including specific capacity (SPC) and transmissivity (T) as well as its related hydrogeological factors in a bedrock aquifer, and subsequently, to produce the regional groundwater productivity potential (GPP) map for the area around Pohang City, Korea using a geographic information system (GIS) and a weights-of-evidence (WOE) model. All of the related factors, including topography, lineament, geology, forest, and soil data were collected and input into a spatial database. In addition, SPC and T data were collected from 83 and 81 well locations, respectively. Four dependent variables including SPC values of ≥6.25m3/d/m (Case 1) and T values of ≥3.79m2/d (Case 3) corresponding to a yield (Y) of ≥500m3/d, and SPC values of ≥3.75m3/d/m (Case 2) and T values of ≥2.61m2/d (Case 4) corresponding to a Y of ≥300m3/d were also input into a spatial database. The SPC and T data were randomly selected in an approximately 70:30 ratio to train and validate the WOE model. Tests of conditional independence were performed for the used factors. To assess the regional GPP for each dependent variable, W+ and W− of each factor’s rating were overlaid spatially. The results of the analysis were validated using area under curve (AUC) analysis with the existing SPC and T data that were not used for the training of the model. The AUC of Cases 1, 2, 3 and 4 showed 0.7120, 0.6893, 0.6920, and 0.7098, respectively. In the case of the dependent variables, Case 1 had an accuracy of 71.20% (AUC: 0.7120), which is the best result produced in this analysis. Such information and the maps generated from it could be used for groundwater management, a practice related to groundwater resource exploration. [Copyright &y& Elsevier]

Summary: This study analyzed the relationships between groundwater specific capacity (SPC) and its related hydrological factors to assess the sensitivity of each factor and map the regional groundwater potential for the area of Pohang City, Korea, using a geographic information system (GIS) and a probability model. All related factors including topography, geology, lineament, and soil data were collected and entered into a spatial database. SPC data were collected from well locations, and SPC values of ≥6.25m3/d/m, corresponding to a yield of 500m3/d, were input to a spatial database. SPC data were then randomly selected in a 66/34 ratio to train and validate the model. A frequency-ratio model and sensitivity analysis were used to determine the relationships between SPC and its related factors and the importance of SPC-related factors. Sensitivity analysis allows for comparison of the combined effects of all factors except for one. The validation of the groundwater potential map overlain by all factors showed 77.78% accuracy. In the sensitivity analysis, the best accuracy was obtained by omitting ground elevation data (78.64%), and the worst accuracy resulted when soil texture was not included (76.64%). The results show that soil texture had the greatest effect on the groundwater potential and ground elevation had the least effect. Such information and the maps generated from it can be applied to groundwater management and groundwater resource exploration. [ABSTRACT FROM AUTHOR]

Abstract: We investigated surface stabilities and stresses of -Sn and their consequences to the nanowire structure through density-functional theory calculations. -Sn nanowires are well known to grow along the [100] direction. Even though the (100) and (010) planes are equivalent in bulk, the surface stresses are found to induce the anisotropic deformation. Along the surface zigzag bond chain direction, large negative surface tensions are found, combined with a linearization tendency of the zigzag bond chains. The negative surface tensions are not typical on metal surfaces and results in the elongation of the -Sn metal nanowires. [Copyright &y& Elsevier]

Abstract: This paper shows that the architecture of a steam generator for a power plant can be deduced on the basis of the constructal law. According to constructal theory, the flow architecture emerges in time such that it provides progressively greater access to its currents. The circulation of water is driven by buoyancy in one large tube (the downcomer) and many parallel smaller tubes (the riser). The total flow volume is fixed. Two flow models are used: single phase liquid in the downcomer and riser, and liquid–vapor mixture in the riser tubes. Features that result from constructal design are: the tube diameters, the number of riser tubes, the water circulation rate, the rate of steam production, and how the flow architecture should change when the operating pressure and the size of the flow system change. [Copyright &y& Elsevier]

Abstract: Coenzyme Q10 (CoQ10) is an electron carrier in the respiration chain with antioxidant activity. The effects of aeration and agitation rates, dissolved oxygen levels, an electron flux inhibitor (azide), a proton gradient releaser (2,4-dinitrophenol (DNP)), and an oxidative stressor (hydrogen peroxide (H2O2)) on the intracellular CoQ10 contents in Agrobacterium tumefaciens ATCC4452 were investigated. With a decrease of dissolved oxygen level from 20 to 5%, the intracellular CoQ10 content increased about four-fold, yielding 2mg/g dry cell weight at 5% dissolved oxygen level. Azide significantly increased the intracellular CoQ10 content, with the highest value of 5.3mg/g dry cell weight in the presence of 0.45mM of sodium azide. However, DNP (up to 200μM) and H2O2 (up to 10μM) did not affect the intracellular CoQ10 content, indicating proton gradient release, and oxidative stress do not affect the synthesis of CoQ10. These results show that restricted electron flux by limited oxygen supply and the addition of azide increases the intracellular CoQ10 content, suggesting a feedback regulation of CoQ10 biosynthesis by its physiological function of electron carrier in the respiration chain. [Copyright &y& Elsevier]

Individual domains from extracellular proteins are potential reagents for biochemical characterization of ligand/receptor interactions and antibody binding sites. Here, we describe an approach for the identification and characterization of stable protein domains with cell surface display in Saccharomyces cerevesiae, using the epidermal growth factor receptor (EGFR) as a model system. Fragments of the EGFR were successfully expressed on the yeast cell surface. The yeast-displayed EGFR fragments were properly folded, as assayed with conformationally specific EGFR antibodies. Heat denaturation of yeast-displayed EGFR proteins distinguished between linear and conformational antibody epitopes. In addition, EGFR-specific antibodies were categorized based on their ability to compete ligand binding, which has been shown to have therapeutic implications. Overlapping EGFR antibody epitopes were determined based on a fluorescent competitive binding assay. Yeast surface display is a useful method for identifying stable folded protein domains from multidomain extracellular receptors, as well as characterizing antibody binding epitopes, without the need for soluble protein expression and purification. [Copyright &y& Elsevier]

We investigate the effect of phosphorus doping on the atomic structure of B-related defects in crystalline Si through first-principles pseudopotential calculations. We find that a B–P complex is the most stable defect, with a binding energy of about 0.3 eV, compared with isolated B and P ions. When Si self-interstitials (Is) are generated by ion implantation, B and P dopants form an Is–B–P complex. The stability of the Is–B–P complex is greatly enhanced as the Fermi level increases, compared with the Is–B complex. The formation of the B–P and Is–B–P complexes is suggested to be responsible for the suppression of B diffusion in Si predoped with donor impurities. [Copyright &y& Elsevier]

We previously demonstrated using restriction landmark genomic scanning-based 2-dimensional genome electrophoresis method decreased results of 16 primary hepatocellular carcinomas (HCCs) revealed reduction of intensity of 60 NotI-landmark spots, and increase in five spots that were frequently observed in HCCs. Most frequently decreased spot (14/16 HCCs) was identified to it corresponds to a gene encoding SSI-1, a JAK-binding protein (SSI-1/SOCS-1/JAB) that regulated the JAK/STAT signal transduction pathway. This signaling pathway is important for relaying signals from various cytokines outside the cell to the inside. Expression level of SOCS-1 messenger RNA was markedly suppressed in 50% of HCCs (4/8). Loss of heterozygosity at the SSI-1 gene, was found in all cases with aberrant expression. Methylation analysis of the CpG-rich regions of SSI-1 gene revealed hypermethylation of these regions. In an additional series of methylation analysis using 30 HCCs, 16 (53%) showed hypermethylation of the gene. These results indicate that the SSI-1 gene is silenced in a substantial portion of HCC though the combined mechanisms of methylation of either 5′ or exon CpG rich regions and by a chromosomal loss of the remaining allele. [Copyright &y& Elsevier]

Ubiquitination is the covalent attachment of ubiquitin (Ub) to substrate proteins and regulates several cellular processes, including protein degradation. Ub ligases (E3s) bring a Ub-conjugated enzyme E2 (E2–Ub) and the target protein closer to enable ubiquitination. In this study, we engineered a U-box domain of human U-box-type E3 E4B (E4BU) to enhance its function as a Ub ligase by accelerating the rate of Ub transfer directly from Ub-loaded human E2 UbcH5b (E2(UbcH5b)–Ub) to the proximal substrate. We developed a functional screening system for the E4BU library using a yeast surface display system combined with fluorescence-activated cell sorting (FACS) to isolate functionally improved variants. This phenotypic screening system yielded an E4BU variant, E4BU(#8), which exhibited an approximately 4-fold greater Ub ligase activity rate in the yeast displayed form than that of the E4BU wild-type. When E4BU(#8) was fused to a green fluorescent protein (GFP)-specific nanobody, the fusion protein polyubiquitinated GFP in proportion to the concentration and incubation time, with an approximately 3-fold faster Ub ligase activity rate than the previously isolated E4BU(NT) variant. Importantly, the engineered E4BU(#8) retained endogenous Lys48-linked polyubiquitination activity, which is essential for substrate degradation by the 26S proteasome. Our results indicated that E4BU(#8), which binds to and allosterically stimulates E2(UbcH5b)–Ub to enhance Ub transferase activity to a substrate, may be valuable in designing biological molecules for targeted protein degradation. [Display omitted] • E4BU, the U-box of E3 E4B, was engineered to enhance its function as ubiquitin ligase. • A yeast surface display-based functional screening of E4BU library was performed. • An engineered E4BU variant, E4BU(#8), exhibits enhanced ubiquitin ligase activity. • E4BU(#8) yields mainly Lys48-linked polyubiquitination to the substrate. • E4BU(#8) may be useful in the design of biologics for targeted protein degradation. [ABSTRACT FROM AUTHOR]

Focuses on the development of a reversible decorrelation algorithm for three-dimensional (3-D) medical images for progressive transmission. Details on the advantages of progressive transmission of an image; Examination of experiments conducted in this research; Description of research methods utilized.

• Our patient showed heterogeneous lesions from cytotoxic and vasogenic edema, and metabolic derangement on brain MRI. • Radiological findings changed heterogeneously on follow-up examinations. • Non-ketotic hyperglycemic chorea-ballism has a complex pathophysiology. [ABSTRACT FROM AUTHOR]

Microsatellite stable (MSS) BRAF p.V600E mutation colorectal cancer (BRAF-CRC) has a poor prognosis, whereas microsatellite instability (MSI) in BRAF-CRC is associated with a favorable prognosis. Although usually considered a single clinical entity, the MSI BRAF-CRC subtype shows some distinct characteristics in comparison with the MSS BRAF-CRC subtype. We conducted a meta-analysis to investigate the influence of clinicopathological features on MSI status in BRAF-CRC. We searched publications up to March 2019 from PubMed, Embase, and the Cochrane Library. The effect of MSI status on outcome parameters was assessed using odds ratios (ORs) with 95% confidence intervals (CIs) and fixed- or random-effects models according to the heterogeneity. After reviewing 2839 reports, 16 eligible studies including 1381 patients with BRAF-CRC met the criteria. The MSI BRAF-CRC subtype was associated with older age, female sex (OR = 1.70; 95% CI = 1.35–2.14; P < 0.00001), proximal tumor location (OR = 5.10; 95% CI = 3.70–7.03; P < 0.00001), early TNM stage (OR = 5.28; 95% CI = 3.93–7.09; P < 0.00001), and poor differentiation (OR = 2.29; 95% CI = 1.60–3.28; P < 0.00001). MSI was significantly correlated with distinct favorable clinicopathological characteristics in BRAF-CRC. These results suggest that MSI status should be considered as a stratification factor for better management of the BRAF-CRC. [ABSTRACT FROM AUTHOR]

Objectives: We aimed to evaluate the sex‐specific effect of apolipoprotein E (APOE) alleles and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism on the biochemical, anatomical, and cognitive profiles of Alzheimer's disease (AD) patients. Methods: The patient (followed‐up for at least 2 years) medical records, which comprised of data on plasma homocysteine and folate levels, lipid profile, HbA1c, MTHFR C677T genotype, APOE allele type, mini‐mental state examination (MMSE) and clinical dementia rating (CDR) scores, and brain scans, were retrospectively analyzed. Two trained neurologists scored the white matter lesions (Fazekas scale), medial temporal lobe atrophy (MTA), and microbleeds using brain magnetic resonance imaging scans. Results: This study included 574 patients clinically diagnosed with probable AD (average age, 73.2 years; mean MMSE score, 10.05). The effect of sex on all parameters was evaluated. The triglyceride (TG) and homocysteine levels and the MTA and Fazekas scores were higher in female APOE‐ε4/ε4 carriers than in women without APOE‐ε4. The TG and homocysteine levels were lower in men with the MTHFR CC allele than in those with the MTHFR TT allele. In contrast, MTHFR polymorphism and APOE‐ε4 alleles were not significantly correlated with anatomical lesions and rate of decline in the MMSE and CDR scores. Conclusions: We demonstrated the sex‐specific effect of the APOE allele and MTHFR polymorphism on the serological and anatomical biomarkers in AD patients. The APOE allele and MTHFR mutations did not directly affect cognitive progression, but differentially affected other biochemical factors, between the sexes. These findings will aid in devising novel preventive and therapeutic strategies. [ABSTRACT FROM AUTHOR]

In this paper, we report a non-equilibrium molecular dynamics study on the length-dependent lattice thermal conductivity of graphene with lengths up to 16 μm at room temperature. In the molecular dynamics simulations, whether the non-equilibrium systems reach the steady states is rigorously investigated, and the times to reach the steady states are found to drastically increase with the lengths of graphene. From the ballistic to the diffusive regime, the lattice thermal conductivities are explicitly calculated and found to keep increasing in a wide range of lengths with finally showing a converging behavior at 16 μm. That obtained macroscopic value of the lattice thermal conductivity of graphene is 3200 W/mK. [ABSTRACT FROM AUTHOR]

We investigate the maximum available free electron carrier density in Al-doped n-type ZnO, based on density-functional theory calculations. The Coulomb interactions between the Al dopants and the Zn-vacancy native acceptors are found to limit the carrier density. In typical growth conditions, the n-type doping limit is found to be in the range of 1019 ∼ 1021 cm-3. [ABSTRACT FROM AUTHOR]

Substitutional doping in 2D semiconductor MoS2 was investigated by charge transition level (CTL) calculations for Nitrogen group (N, P, As, Sb) and Halogen group (F, Cl, Br, I) dopants at the S site of monolayer MoS2. Both n-type and p-type dopant levels are calculated to be deep mid-gap states (~1 eV from band edges) from DFT total energy-based CTL and separate DFT + GW calculations. The deep dopant levels result from the giant renormalization of hydrogen-like defect states by reduced dielectric screening in ultrathin 2D films. Theoretical analysis based on Keldysh formulation provides a consistent impurity binding energy of ~1 eV for dielectric thin films. These findings of intrinsic deep impurity levels in 2D semiconductors MoS2 may be applicable to diverse novel emerging device applications. [ABSTRACT FROM AUTHOR]

Immunotoxins (ITs) are attractive anticancer modalities aimed at cancer-specific delivery of highly potent cytotoxic protein toxins. An IT consists of a targeting domain (an antibody, cytokine, or another cell-binding protein) chemically conjugated or recombinantly fused to a highly cytotoxic payload (a bacterial and plant toxin or human cytotoxic protein). The mode of action of ITs is killing designated cancer cells through the effector function of toxins in the cytosol after cellular internalization via the targeted cell-specific receptor-mediated endocytosis. Although numerous ITs of diverse structures have been tested in the past decades, only 3 ITs—denileukin diftitox, tagraxofusp, and moxetumomab pasudotox—have been clinically approved for treating hematological cancers. No ITs against solid tumors have been approved for clinical use. In this review, we discuss critical research and development issues associated with ITs that limit their clinical success as well as strategies to overcome these obstacles. The issues include off-target and on-target toxicities, immunogenicity, human cytotoxic proteins, antigen target selection, cytosolic delivery efficacy, solid-tumor targeting, and developability. To realize the therapeutic promise of ITs, novel strategies for safe and effective cytosolic delivery into designated tumors, including solid tumors, are urgently needed. [ABSTRACT FROM AUTHOR]

The aging-associated cellular and molecular changes in esophagus have not been established, yet. Thus we evaluated histological structure, interstitial cells of Cajal (ICCs), neuronal nitric oxide synthase (nNOS)-positive cells, and contractility in the esophagus of Fischer 344 rat at different ages (6-, 31-, 74-weeks, and 2-years). The lamina propria thickness and endomysial area were calculated. The immunoreactivity of c-Kit, nNOS and protein gene product (PGP) 9.5 was counted after immunohistochemistry. Expression of c-Kit, stem cell factor (SCF), nNOS and PGP 9.5 mRNA was measured by real-time PCR, and expression of c-Kit and nNOS protein was detected by Western blot. Isovolumetric contractile force measurement and electrical field stimulation (EFS) were conducted. The lamina propria thickness increased (6 week vs 2 year, P = 0.005) and the endomysial area of longitudinal muscle decreased with aging (6 week vs 2 year, P<0.001), while endomysial area of circular muscle did not significantly decrease. The proportions of NOS-immunoreactive cells and c-Kit-immunoreactive areas declined with aging (6 week vs 2 year; P<0.001 and P = 0.004, respectively), but there was no significant change of PGP 9.5-immunopositiviy. The expressions of nNOS, c-Kit and SCF mRNA also reduced with aging (6 week vs 2 year; P = 0.006, P = 0.001 and P = 0.006, respectively), while the change of PGP 9.5 mRNA expression was not significant. Western blot showed the significant decreases of nNOS and c-Kit protein expression with aging (6 week vs 2 year; P = 0.008 and P = 0.012, respectively). The EFS-induced esophageal contractions significantly decreased in 2-yr-old rat compared with 6-wk-old rats, however, L-NG-Nitroarginine methylester did not significantly increase the spontaneous and EFS-induced contractions in the 6-wk- and 2-yr-old rat esophagus. In conclusion, an increase of lamina propria thickness, a decrease of endomysial area, c-Kit, SCF and NOS expression with preserved total enteric neurons, and contractility in aged rat esophagus may explain the aging-associated esophageal dysmotility. [ABSTRACT FROM AUTHOR]

Novel tridentate N2O‐type ligands L1–L4 (((((X‐benzyl)pyridine‐2‐yl)methylamino)methyl)phenol); L1 for X=4‐CH3, L2 for X=H, L3 for X=2‐F, L4 for X=4‐CF3) and their dinuclear copper(II) complexes C1–C4 (C1 for [(L1)2Cu2(NO3)2], C2 for [(L2)2Cu2(NO3)2], C3 for [(L3)2Cu2(NO3)2] and C4 for [(L4)2Cu2(NO3)2]) was synthesized and verified by 1H NMR, IR, and ESI‐Mass. The structural forms of the copper complexes were determined by X‐ray crystallography. The dinuclear copper complexes C1–C4 showed efficient ring‐opening properties of epoxides with methanol under mild conditions. In particular, the copper complex C1 having electron‐donating group in the ligand showed the most efficient reactivity in the ring opening of epoxides. The sole attack at the benzylic carbon of styrene oxide and the less steric preference in 1,2‐epoxyhexane demonstrated that the regiochemistry of the ring opening catalyzed by dinuclear copper complexes might be dependent on the electronic feature of epoxide. [ABSTRACT FROM AUTHOR]

Objectives: Gastric cancer (GC) is the fourth most common cancer worldwide, with the highest incidence and mortality regardless of sex. Despite technological advances in diagnosing and treating gastric cancer, GC still has high incidence and mortality rates. Therefore, continuous research is needed to overcome GC. In various studies, cell lines are used to find and verify the cause of specific diseases. Large-scale genomic studies such as ENCODE and Roadmap epigenomic projects provide multiomics data from various organisms and samples. However, few multi-omics data for gastric tissues and cell lines have been generated. Therefore, we performed RNA-seq, Exome-seq, and ChIP-seq with several gastric cell lines to generate a multi-omics data set in gastric cancer. Data description: Multiomic data, such as RNA-seq, Exome-seq, and ChIP-seq, were produced in gastric cancer and normal cell lines. RNA-seq data were generated from nine GC and one normal gastric cell line, mapped to a human reference genome (hg38) using the STAR alignment tool, and quantified with HTseq. Exome sequence data were produced in nine GC and two normal gastric lines. Sequenced reads were mapped and processed using BWA-MEM and GATK, variants were called by stralka2, and annotation was performed using ANNOVAR. Finally, for the ChIP-seq, nine GC cell lines and four GC cell lines were used in two experimental sets; chip-seq was performed to confirm changes in H3K4me3 and H3K27me3. Data was mapped to human reference hg38 with BWA-MEM, and peak calling and annotation were performed using the Homer tool. Since these data provide multi-omics data for GC cell lines, it will be useful for researchers who use the GC cell lines to study. [ABSTRACT FROM AUTHOR]

Smoking is a risk factor for gastric cancer (GC) and causes oxidative stress. Antioxidant vitamins may protect against oxidative stress. This study aimed to determine the association between dietary antioxidant vitamin intake and GC risk according to smoking status and the histological subtype. This case-control study included 286 pairs of patients with GC and controls aged 20–79 years enrolled at two hospitals from 2002 to 2006, matched by age (± 2 years), sex, hospital, and participation period (± 1 years). Dietary information was collected using a quantitative food frequency questionnaire (FFQ). When stratified by smoking status, increased intake of vitamin C (OR = 0.38; 95% CI = 0.17–0.84 for highest vs. lowest; P for trend = 0.033) and folate (OR = 0.28; 95% CI = 0.12–0.64 for highest vs. lowest; P for trend = 0.003) decreased GC risk in nonsmokers. Vitamin C (P for interaction = 0.043) and folate (P for interaction =0.015) levels were significantly associated with smoking status. Similar results were observed in nonsmokers with diffuse and mixed types of GC, but not in those with intestinal type of GC. Therefore, we found an inverse association between higher intake of dietary vitamin C and folate with the risk of GC among nonsmokers. These protective associations were strong in nonsmokers with diffuse and mixed types of GC. [ABSTRACT FROM AUTHOR]

Simple Summary: Somatostatin receptor 2 (SSTR2) is a key regulator of gastric acid secretion in the gastric epithelium. We revealed that SSTR2 promoter is hypermethylated in intestinal metaplasia, dysplasia, and gastric tumors, associating with gene silencing. We suggest that SSTR2 promoter methylation is initiated in aged gastric mucosae infected with Helicobacter pylori and consequential SSTR2 silencing promotes the establishment of inflammatory microenvironment via the intrinsic pathway, providing new insights into gastric carcinogenesis. The loss-of-function variants are thought to be associated with inflammation in the stomach. We here aimed to evaluate the extent and role of methylation at the SSTR2 promoter in inflammation and gastric tumor formation. A whole-genome bisulfite sequencing analysis revealed that the SSTR2 promoter was significantly hypermethylated in gastric tumors, dysplasia, and intestinal metaplasia compared to non-tumor tissues from patients with gastric cancer. Using public data, we confirmed SSTR2 promoter methylation in primary gastric tumors and intestinal metaplasia, and even aged gastric mucosae infected with Helicobacter pylori, suggesting that aberrant methylation is initiated in normal gastric mucosa. The loss-of-function of SSTR2 in SNU638 cell-induced cell proliferation in vitro, while stable transfection of SSTR2 in AGS and MKN74 cells inhibited cell proliferation and tumorigenesis in vitro and in vivo. As revealed by a comparison of target genes differentially expressed in these cells with hallmark molecular signatures, inflammation-related pathways were distinctly induced in SSTR2-KO SNU638 cell. By contrast, inflammation-related pathways were inhibited in AGS and MKN74 cells ectopically expressing SSTR2. Collectively, we propose that SSTR2 silencing upon promoter methylation is initiated in aged gastric mucosae infected with H. pylori and promotes the establishment of an inflammatory microenvironment via the intrinsic pathway. These findings provide novel insights into the initiation of gastric carcinogenesis. [ABSTRACT FROM AUTHOR]

Background/Objectives: The hormone-dependent effect of MAP3K1 gene polymorphisms may explain sex-specific differences in gastric cancer (GC) risk. Phytoestrogens have been shown to interact with this genetic factor. Here, we investigated the association between MAP3K1 gene polymorphisms and GC risk by sex and whether these associations differ depending on soy products intake. Methods: Participants aged 20–79 years were recruited from two hospitals between December 2002 and September 2006. In all, 440 cases and 485 controls were recruited, among, 246 pairs of cases and controls, matched by sex, age (± 5 years), study admission period (± 1 years), and hospital, were included for the analysis. Results: In dominant model, men with the A allele of rs252902 showed significantly increased GC risk (odd ratio; OR=2.19, 95% confidence interval; CI=1.31–3.64) compared to GG homozygotes. When stratified by intake of soy products, men with the A allele of rs252902 and low intake of soy products showed significantly higher GC risk (OR=3.29, 95% CI=1.55–6.78) than that in GG homozygotes. Conclusions: Men with the risk allele of MAP3K1 had a significantly increased GC risk compared to GG homozygotes; this trend was more pronounced in those with low intake of soy products. [ABSTRACT FROM AUTHOR]

Sodium and zinc display opposite effects on immune cells, such as regulatory T cells (Tregs) and T helper 17 cells (Th17), resulting in an altered immune response. Immune cells have a pivotal role in regulating tumor progression, which may affect gastric cancer (GC) mortality. Thus, this cohort study investigated the associations between the combination of sodium and zinc intake and GC mortality and whether these associations differ by histological type by following up deaths of GC cases in Korea. A total of 490 patients with GC were enrolled between 2002 and 2006. Survival or death was prospectively followed up until December 31, 2016. Finally, 300 patients with the two main histological types of GC were included; 99 GC deaths occurred during a median follow-up period of 7.1 years. Patients with high sodium and low zinc intake had a significantly higher GC mortality than those with low sodium and high zinc intake (hazard ratio [HR], 2.07; 95% confidence interval [CI], 1.09–3.93). However, no significant association was found between the histological types of GC. In conclusion, we found that high sodium and low zinc intake may worsen the survival rate of patients with GC. [ABSTRACT FROM AUTHOR]

Nitrogen- and boron-doped amorphous carbon layers (ACLs) were grown by plasma- enhanced chemical vapor deposition (PECVD) on a Si substrate and characterized by Raman and X-ray photoelectron spectroscopy (XPS) techniques. Increasing doping levels resulted in a shift in the Raman G-peak of the doped ALCs, indicating a change in bond lengths upon doping. The XPS N1s and B1s spectra revealed the presence of different types of N-related (involving pyridinic, pyrrolinic, and graphitic N) and B-related (corresponding to BC 2 O and B C species) bonds in the N- and B-doped ACLs, with N and B doping levels ranging from 2.03 to 3.94 at.% and from 1.44 to 10.4 at.%, respectively. These results suggest that the dry etch resistance of the present ACLs was enhanced by B doping and negatively affected by N doping. Density functional theory calculations highlighted the strengthening of C C bonds induced by B doping and their corresponding weakening caused by N doping as possible explanations for the effects of doping on the dry etching characteristics of the ACLs. [ABSTRACT FROM AUTHOR]

Transparent amorphous oxide semiconductors (TAOS's) are of practical importance for applications including oxide electronics and displays. Here we show the lone-pair s-electrons incorporated by for example Sb-doping can suppress the hole-induced lattice instability, which has been a major obstacle to commercial application of the TAOS-based thin film transistors. The Sb(III)-O spσ* hybridization in the top-most valence states makes the lone-pair s-electrons to capture the excited holes, the Sb(V)O6 octahedral bonding configuration by which formed is easily dissociated into the stable lone-pair Sb(III) state by recapturing conduction electrons. [ABSTRACT FROM AUTHOR]

Abstract: We investigate the role of the O-vacancy in ZnO. The vacancy is well-known to be rich in ZnO and the origin of the natural n-type conductivity. The electronic structure of the O-vacancy examined by the accurate GW calculations indicates that it is a deep donor. By considering the interactions between the O-vacancy and the other native point defects in O-deficient ZnO through density-functional theory calculations, the presence of O-vacancy induces the formation of Zn-interstitial which is a shallow donor. A quantum mechanical attractive interaction between the deep O-vacancy donor and the shallow Zn-interstitial donor, which comes from the electronic orbital hybridization, is discussed. [Copyright &y& Elsevier]