Electron Spin Broken-Symmetry of Fe-Co Diatomic Pairs to Promote Kinetics of Bifunctional Oxygen Electrocatalysis for Zinc-Air Batteries.

Designing bifunctional catalysts to reduce the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) reaction barriers while accelerating the reaction kinetics is perceived to be a promising strategy to improve the performance of Zinc-air batteries. Unsymmetric configuration in single-atom catalysts has attracted attention due to its unique advantages in regulating electron orbitals. In this work, a seesaw effect in unsymmetric Fe-Co bimetallic monoatomic configurations is proposed, which can effectively improve the OER/ORR bifunctional activity of the catalyst. Compared with the symmetrical model of Fe-Co, a strong charge polarization between Co and Fe atoms in the unsymmetric model is detected, in whom the spin-down electrons around Co atoms are much higher than those spin-up electrons. The seesaw effect occurred between Co atoms and Fe atoms, resulting in a negative shift of the d-band center, which means that the adsorption of oxygen intermediates is weakened and more conducive to their dissociation. The optimized reaction kinetics of the catalyst leads to excellent performance in ZABs, with a peak power density of 215 mW cm-2 and stable cycling for >1300 h and >4000 cycles. Flexible Zinc-air batteries have also gained excellent performance to demonstrate their potential in the field of flexible wearables.

Synergistic effect of two bacterial strains promoting anaerobic digestion of rice straw to produce methane.

A large amount of agricultural waste causes global environmental pollution. Biogas production by microbial pretreatment is an important way to utilize agricultural waste resources. In this study, Sporocytophaga CG-1 (A, cellulolytic strain) was co-cultured with Bacillus clausii HP-1 (B, non-cellulolytic strain) to analyze the effect of pretreatment of rice straw on methanogenic capacity of anaerobic digestion (AD). The results showed that weight loss rate of filter paper of co-culture combination is 53.38%, which is 29.37% higher than that of A. The synergistic effect of B on A can promote its degradation of cellulose. The cumulative methane production rate of the co-culture combination was the highest (93.04 mL/g VS substrate), which was significantly higher than that of A, B and the control group (82.38, 67.28 and 67.70 mL/g VS substrate). Auxiliary bacteria can improve cellulose degradation rate by promoting secondary product metabolism. These results provide data support for the application of co-culture strategies in the field of anaerobic digestion practices.

Effects of temperature and charged vacancies on electronic and optical properties of ß-Ga2O3 after radiation damage.

ß-Ga2O3 as an ultra-wide bandgap material is widely used in space missions and nuclear reactor environments. It is well established that the physical properties of ß-Ga2O3 would be affected by radiation damage and temperature in such application scenarios. Defects are inevitably created in ß-Ga2O3 upon irradiation and their dynamic evolution is positively correlated with the thermal motion of atoms as temperature increases. This work utilizes first-principles calculations to investigate how temperature influences the electronic and optical properties of ß-Ga2O3 after radiation damage. It finds that the effect of p-type defects caused by Ga vacancies on optical absorption diminishes as temperature increases. The high temperature amplifies the effect of oxygen vacancies to ß-Ga2O3, however, making n-type defects more pronounced and accompanied by an increase in the absorption peak in the visible band. The self-compensation effect varies when ß-Ga2O3 contains both Ga vacancies and O vacancies at different temperatures. Moreover, in the case of Ga3- (O2+) vacancies, the main characters of p(n)-type defects caused by uncharged Ga0 (O0) vacancies disappear. This work aims to understand the evolution of physical properties of ß-Ga2O3 under irradiation especially at high temperatures, and help analyze the damage mechanism in ß-Ga2O3-based devices.

Preparation and characterization of soluble dietary fiber from tiger nut residues, showing enhanced antioxidant activity and metal-ion-binding properties.

To improve the utilization of soluble dietary fiber (SDF) from tiger nut residues, the response surface methodology was used to optimize the conditions of superfine grinding to produce SDF with antioxidant and metal-ion-binding properties. The yield was increased (30.56%) and the average particle diameter of SDF was decreased (D50: 32.80 µm) under the optimal conditions (a proportion of grinding medium of 100%, a feeding mass of 0.90 kg, a grinding time of 20 min, and a moisture content of 8.00%). In addition, superfine grinding substantially modified the surface morphology and increased the SDF content and the proportion of monosaccharides by decreasing the molecular weight. Moreover, superfine grinding remarkably enhanced the in vitro antioxidant activities (ABTS+, DPPH, and ·OH) of the SDF, which also exhibited favorable metal-ion-binding properties (Ca2+, Zn2+, and Co2+). These results suggest that superfine grinding can be used as a technique to modify dietary fiber to manufacture functional SDF.

Ameliorative effects of pine nut peptide-zinc chelate (Korean pine) on a mouse model of Alzheimer's disease.

In this study, 50 SD adult male mice were used to create an Alzheimer's disease model. The mice's learning and memory abilities were evaluated using an eight-arm radial maze experiment, and changes in body weight and food intake were noted. This helped to better validate the improvement of Alzheimer's disease caused by pine nut peptide-zinc chelate (Korean pine). For a more thorough investigation, mice's brains were dissected, Endogenous mercaptan antioxidants (enzymes), which are markers of brain tissue, were assessed, and mouse gut flora was analyzed. The findings demonstrated that pine nut peptide-zinc chelate (Korean pine) can improve learning and memory, stop brain aging and damage, and control gut flora in mice. It may exert its effects by ameliorating decreased AChE levels and increased ChAT levels in the central cholinergic system, endogenous thiol antioxidants (enzymes) in the cerebral cortex, and by controlling the bacterial flora in the gut.

First-principles study of thermal transport properties in ferroelectric HfO2 and related fluorite-structure ferroelectrics.

The discovery of ferroelectricity in the fluorite-structure HfO2 has attracted much interest in various applications including electro-optic devices and nonvolatile memories. Doping and alloying not only induce ferroelectricity in HfO2, but also significantly impact the thermal conduction which plays an essential role in the heat dissipation and thermal stability of ferroelectric devices. To understand and regulate the heat transfer in ferroelectric HfO2, it is crucial to investigate the thermal conduction properties of related fluorite-structure ferroelectrics so as to establish the structure-property relationship. In this work, using first-principles calculations, we investigate the thermal transport in twelve fluorite-structure ferroelectrics. We find an overall satisfactory agreement between the calculated thermal conductivities and those predicted by the simple theory of Slack. Among the family of fluorite-structure ferroelectrics, the transition-metal oxides HfO2 and ZrO2 have the highest thermal conductivities due to the strong interatomic bonding. We demonstrate that the spontaneous polarization, a feature specific to ferroelectrics, is positively correlated with the thermal conductivity, namely, the larger the spontaneous polarization, the larger the thermal conductivity. This is of chemical origin, namely, both the spontaneous polarization and the thermal conductivity are positively correlated to the "ionicity" of the ferroelectrics. We further find that the thermal conductivity is several times lower in the ferroelectric solid solution Hf1-xZrxO2 than in its pure counterparts, especially in the thin films where the finite size effect further suppresses thermal conduction. Our findings suggest the spontaneous polarization as a specific criterion for identifying ferroelectrics with desired thermal conductivities, which may promote the design and application of ferroelectrics.

Temperature-dependent UV-Vis dielectric functions of BaTiO3 across ferroelectric-paraelectric phase transition.

Ferroelectric BaTiO3 with an electric-field-switchable spontaneous polarization has attracted wide attention in photovoltaic applications due to its efficient charge separation for photoexcitation. The evolution of its optical properties with rising temperature especially across the ferroelectric-paraelectric phase transition is critical to peer into the fundamental photoexcitation process. Herein, by combining spectroscopic ellipsometry measurements with first-principles calculations, we obtain the UV-Vis dielectric functions of perovskite BaTiO3 at temperatures varying from 300 to 873 K and provide the atomistic insights into the temperature-driven ferroelectric-paraelectric (tetragonal-cubic) structural evolution. The main adsorption peak in dielectric function of BaTiO3 is reduced by 20.6% in magnitude and redshifted as temperature increases. The Urbach tail shows an unconventional temperature-dependent behavior due to the microcrystalline disorder across the ferroelectric-paraelectric phase transition and the decreased surface roughness at around 405 K. From ab initio molecular dynamics simulations, the redshifted dielectric function of ferroelectric BaTiO3 coincidences with the reduction of the spontaneous polarization at elevated temperature. Moreover, a positive (negative) external electric field is applied which can modulate the dielectric function of ferroelectric BaTiO3 blueshift (redshift) with a larger (smaller) spontaneous polarization since it drives the ferroelectric further away from (closer to) the paraelectric structure. This work sheds light on the temperature-dependent optical properties of BaTiO3 and provides data support for advancing its ferroelectric photovoltaic applications.

Electrical Failure Mechanism in Stretchable Thin-Film Conductors.

Stretchable thin-film conductors are basic building blocks in advanced flexible and stretchable electronics. Current research mainly focuses on strategies to improve stretchability and widen the range of applications of stretchable conductors. However, stability should not be neglected, and the electrical failure mode is one of the most common stability issues that determines the current range and duration in a circuit. In this work, we report the electrical failure mechanism of stretchable conductors. We find a special failure mode for the stretchable conductors, which can be attributed to the coupling effect between local thermal strains and dynamic resistance changes of the thin film. This creates a vicious circle that significantly differs from traditional conductors. Physical parameters related to this special failure mode are investigated in detail. It is found that this mechanism is applicable to different kinds of stretchable conductors. Based on this finding, we also explore methods to modulate the failure of stretchable conductors. The failure mechanism found here provides a fundamental understanding of the current effect of stretchable circuits and is crucial for designing stable stretchable bioelectrodes and circuits.

Modifying Ti3C2 MXene with NH4+ as an excellent anode material for improving the performance of microbial fuel cells.

Poor anode performance is one of the main bottlenecks in the development of microbial fuel cells (MFCs) for practical applications. Multilayered Ti3C2 MXene (m-MXene) is an alternative anode modification material because of its high specific surface area and electrical conductivity. However, the multilayered structure, negatively charged surface, and electropositivity of m-MXene could limit its modification effects. In this work, we used a solution-phase flocculation method (ammonium ion method) to restack and aggregate MXene nanosheets as an anode modification material (n-MXene). The n-MXene-modified anode had a higher specific surface area, surface hydrophilicity and surface electropositivity than the m-MXene-modified anode. The n-MXene-modified anode obtained a maximum current density of 2.1 A m-2, which was 31.2% and 61.5% higher than that of the m-MXene-modified anode (1.6 A m-2) and bare carbon fiber cloth anode (1.3 A m-2). This improved anode performance was attributed to both the decrease in the charge transfer resistance and diffusion resistance, which were related to the increased quantity of biomass and microbial nanowire (or pili)-shaped filaments on the electrode surface. This work provides a simple and cost-effective approach to prepare MXene nanosheets for the modification of MFC anodes.

Parent tRNA Modification Status Determines the Induction of Functional tRNA-Derived RNA by Respiratory Syncytial Virus Infection.

tRNA-derived RNA fragments (tRFs) are a recently discovered family of small noncoding RNAs (sncRNAs). We previously reported that respiratory syncytial virus (RSV) infection induces functional tRFs, which are derived from a limited subset of parent tRNAs, in airway epithelial cells. Such induction is also observed in nasopharyngeal wash samples from RSV patients and correlates to RSV genome copies, suggesting a clinical significance of tRFs in RSV infection. This work also investigates whether the modification of parent tRNAs is changed by RSV to induce tRFs, using one of the most inducible tRFs as a model. We discovered that RSV infection changed the methylation modification of adenine at position 57 in tRNA glutamic acid, with a codon of CTC (tRNA-GluCTC), and the change is essential for its cleavage. AlkB homolog 1, a previously reported tRNA demethylase, appears to remove methyladenine from tRNA-GluCTC, prompting the subsequent production of tRFs from the 5'-end of tRNA-GluCTC, a regulator of RSV replication. This study demonstrates for the first time the importance of post-transcriptional modification of tRNAs in tRF biogenesis following RSV infection, providing critical insights for antiviral strategy development.

A General LC-MS-Based Method for Direct and De Novo Sequencing of RNA Mixtures Containing both Canonical and Modified Nucleotides.

Mass spectrometry (MS)-based sequencing has advantages in direct sequencing of RNA, compared to cDNA-based RNA sequencing methods, as it is completely independent of enzymes and base complementarity errors in sample preparation. In addition, it allows for sequencing of different RNA modifications in a single study, rather than just one specific modification type per study. However, many technical challenges remain in de novo MS sequencing of RNA, making it difficult to MS sequence mixed RNAs or to differentiate isomeric modifications such as pseudouridine (Ψ) from uridine (U). Our recent study incorporates a two-dimensional hydrophobic end labeling strategy into MS-based sequencing (2D-HELS MS Seq) to systematically address the current challenges in MS sequencing of RNA, making it possible to directly and de novo sequence purified single RNA and mixed RNA containing both canonical and modified nucleotides. Here, we describe the method to sequence representative single-RNA and mixed-RNA oligonucleotides, each with a different sequence and/or containing modified nucleotides such as Ψ and 5-methylcytosine (m5C), using 2D-HELS MS Seq.

Insights into the thermal conductivity of MOF-5 from first principles.

Metal-organic frameworks (MOFs) have been extensively studied in many fields due to their abundant porous structures. The mechanism underlying the thermal conduction properties of MOFs, which plays an essential role in a wide variety of applications such as adsorbents and thermoelectric devices, remains elusive. It is also highly desirable to achieve the efficient modulation of thermal conductivity in MOFs via experimentally accessible methods such as metal substitution and strain engineering. In this work, we perform first-principles calculations to investigate the thermal transport properties of MOF-5, a representative prototype of MOFs. We find an ultralow thermal conductivity (κ) of 0.33 W m-1 K-1 at room temperature, in excellent agreement with the experimental measurement. Such ultralow κ is attributed to the strong phonon-phonon scattering that arises from the dense and intertwined low-frequency phonons. The phonon dispersion leads to unusual tuning strategies of κ, since conventional designing guidelines (e.g. substitution of heavier atoms or application of tensile strain is preferred in pursuit of lower thermal conductivity) are not fully obeyed in MOF-5. We find that isovalent substitutions of Zn atoms with (lighter) Mg and (heavier) Cd atoms both result in significant reduction of κ, due to the enhanced phonon scattering rates that are associated with the stronger bond strength and the larger atomic mass, respectively. We further demonstrate that the so-called "guitar string" vibrations are responsible for the anomalous non-monotonic variation of κ in MOF-5 under tensile strain. This work provides fundamental insights into the thermal transport mechanisms in MOF-5, which may have some important implications for the thermal management applications utilizing MOFs.

2D-HELS MS Seq: A General LC-MS-Based Method for Direct and de novo Sequencing of RNA Mixtures with Different Nucleotide Modifications.

Mass spectrometry (MS)-based sequencing approaches have been shown to be useful in direct sequencing RNA without the need for a complementary DNA (cDNA) intermediate. However, such approaches are rarely applied as a de novo RNA sequencing method, but used mainly as a tool that can assist in quality assurance for confirming known sequences of purified single-stranded RNA samples. Recently, we developed a direct RNA sequencing method by integrating a 2-dimensional mass-retention time hydrophobic end-labeling strategy into MS-based sequencing (2D-HELS MS Seq). This method is capable of accurately sequencing single RNA sequences as well as mixtures containing up to 12 distinct RNA sequences. In addition to the four canonical ribonucleotides (A, C, G, and U), the method has the capacity to sequence RNA oligonucleotides containing modified nucleotides. This is possible because the modified nucleobase either has an intrinsically unique mass that can help in its identification and its location in the RNA sequence, or can be converted into a product with a unique mass. In this study, we have used RNA, incorporating two representative modified nucleotides (pseudouridine (Ψ) and 5-methylcytosine (m5C)), to illustrate the application of the method for the de novo sequencing of a single RNA oligonucleotide as well as a mixture of RNA oligonucleotides, each with a different sequence and/or modified nucleotides. The procedures and protocols described here to sequence these model RNAs will be applicable to other short RNA samples (<35 nt) when using a standard high-resolution LC-MS system, and can also be used for sequence verification of modified therapeutic RNA oligonucleotides. In the future, with the development of more robust algorithms and with better instruments, this method could allow sequencing of more complex biological samples.

Adsorption of hexavalent chromium using modified walnut shell from solution.

Modified walnut shell (MWS) was obtained using diethylenetriamine through a grafting reaction and its adsorption capacity toward Cr(VI) was enhanced. The adsorbent was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and elemental analysis and the results showed that the modification was effective. To optimize experimental conditions, the effect of temperature, solution pH, salinity, contact time, and Cr(VI) concentration on adsorption quantity were performed in batch mode. It showed that the adsorption ability for Cr(VI) onto MWH can reach 50.1 mg·g-1 at 303 K with solution pH 3. Both the solution pH and salinity had a great impact on the adsorption capacity. The Langmuir model can predict the equilibrium process while the pseudo-second-order model can describe the kinetic process. The Yan model can be used to predict the column process. Additionally, there was also some regeneration ability for Cr-loaded MWH. Consequently, MWS is effective for removing Cr(VI) from solution.

Direct Sequencing of tRNA by 2D-HELS-AA MS Seq Reveals Its Different Isoforms and Dynamic Base Modifications.

Post-transcriptional modifications are intrinsic to RNA structure and function. However, methods to sequence RNA typically require a cDNA intermediate and are either not able to sequence these modifications or are tailored to sequence one specific nucleotide modification only. Interestingly, some of these modifications occur with <100% frequency at their particular sites, and site-specific quantification of their stoichiometries is another challenge. Here, we report a direct method for sequencing tRNAPhe without cDNA by integrating a two-dimensional hydrophobic RNA end-labeling strategy with an anchor-based algorithm in mass spectrometry-based sequencing (2D-HELS-AA MS Seq). The entire tRNAPhe was sequenced and the identity, location, and stoichiometry of all eleven different RNA modifications was determined, five of which were not 100% modified, including a 2'-O-methylated G (Gm) in the wobble anticodon position as well as an N2, N2-dimethylguanosine (m22G), a 7-methylguanosine (m7G), a 1-methyladenosine (m1A), and a wybutosine (Y), suggesting numerous post-transcriptional regulations in tRNA. Two truncated isoforms at the 3'-CCA tail of the tRNAPhe (75 nt with a 3'-CC tail (80% abundance) and 74 nt with a 3'-C tail (3% abundance)) were identified in addition to the full-length 3'-CCA-tailed tRNAPhe (76 nt, 17% abundance). We discovered a new isoform with A-G transitions/editing at the 44 and 45 positions in the tRNAPhe variable loop, and discuss possible mechanisms related to the emergence and functions of the isoforms with these base transitions or editing. Our method revealed new isoforms, base modifications, and RNA editing as well as their stoichiometries in the tRNA that cannot be determined by current cDNA-based methods, opening new opportunities in the field of epitranscriptomics.

Associations of genetic polymorphisms in CTLA-4 and IL-18 with chronic liver diseases: Evidence from a meta-analysis.

BACKGROUND: The aim of this meta-analysis was to explore associations between polymorphisms in CTLA-4/IL-18 and chronic liver diseases by combing the results of all relevant studies. METHODS: Eligible studies were searched from Pubmed, Embase, Web of Science and Cochrane library. We used Review Manager to combine the results of eligible studies. RESULTS: Sixty-seven studies were included in this meta-analysis. Combined results revealed that CTLA-4 rs231775 (dominant, recessive and allele comparisons), IL-18 rs1946518 (dominant, recessive and allele comparisons) and IL-18 rs187238 (dominant, over-dominant and allele comparisons) polymorphisms were all significantly associated with chronic liver diseases in the overall population. We also obtained similar positive results for rs231775, rs5742909, rs3087243, rs1946518 and rs187238 polymorphisms in subgroup analyses by ethnicity and type of disease. CONCLUSIONS: This meta-analysis demonstrated that CTLA-4 rs231775, CTLA-4 rs5742909, CTLA-4 rs3087243, IL-18 rs1946518 and IL-18 rs187238 polymorphisms may confer susceptibility to certain types of chronic liver diseases.

Associations of polymorphisms in CTLA-4 and IL-18 with liver diseases: evidence from a meta-analysis.

BACKGROUND: Associations between polymorphisms in cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) / interleukin-18 (IL-18) and susceptibility to liver diseases were already reported by many publications. The aim of this meta-analysis was to clarify associations between polymorphisms in CTLA-4/IL-18 and liver diseases by combing the results of all relevant publications. METHODS: Eligible publications were searched from Pubmed, Embase, WOS and CNKI. The latest literature searching update was performed on 2nd October, 2019. We used Review Manager to combine the results of individual studies. RESULTS: Sixty-seven studies were included in this study. Combined results revealed that CTLA-4 rs231775 (dominant comparison: OR 0.83, 95 % CI 0.79-0.88; recessive comparison: OR 1.33, 95 % CI 1.23-1.43; allele comparison: OR 0.84, 95 % CI 0.78-0.90), IL-18 rs1946518 (dominant comparison: OR 0.85, 95 % CI 0.78-0.92; recessive comparison: OR 1.29, 95 % CI 1.13-1.48; allele comparison: OR 0.79, 95 % CI 0.71-0.88) and IL-18 rs187238 (dominant comparison: OR 1.28, 95 % CI 1.07-1.53; over-dominant comparison: OR 0.81, 95 % CI 0.68-0.97; allele comparison: OR 1.22, 95 % CI 1.07-1.39) polymorphisms were all significantly associated with liver diseases in the general population. We also obtained similar significant associations for CTLA-4 rs231775, CTLA-4 rs5742909, CTLA-4 rs3087243, IL-18 rs1946518 and IL-18 rs187238 polymorphisms in subgroup analyses. CONCLUSIONS: Collectively, this meta-analysis proved that CTLA-4 rs231775, CTLA-4 rs5742909, CTLA-4 rs3087243, IL-18 rs1946518 and IL-18 rs187238 polymorphisms may confer susceptibility to various types of liver diseases.

A general LC-MS-based RNA sequencing method for direct analysis of multiple-base modifications in RNA mixtures.

A complete understanding of the structural and functional potential of RNA requires understanding of chemical modifications and non-canonical bases; this in turn requires advances in current sequencing methods to be able to sequence not only canonical ribonucleotides, but at the same time directly sequence these non-standard moieties. Here, we present the first direct and modification type-independent RNA sequencing method via introduction of a 2-dimensional hydrophobic end-labeling strategy into traditional mass spectrometry-based sequencing (2D HELS MS Seq) to allow de novo sequencing of RNA mixtures and enhance sample usage efficiency. Our method can directly read out the complete sequence, while identifying, locating, and quantifying base modifications accurately in both single and mixed RNA samples containing multiple different modifications at single-base resolution. Our method can also quantify stoichiometry/percentage of modified RNA versus its canonical counterpart RNA, simulating a real biological sample where modifications exist but may not be 100% at a particular site in the RNA. This method is a critical step towards fully sequencing real complex cellular RNA samples of any type and containing any modification type and can also be used in the quality control of modified therapeutic RNAs.

Ex vivo liver resection and autotransplantation versus allotransplantation for end-stage hepatic alveolar echinococcosis.

OBJECTIVE: The aim of this study was to compare the clinical outcomes of ex vivo liver resection and autotransplantation (ERAT) with allotransplantation in patients with end-stage hepatic alveolar echinococcosis (HAE). METHODS: From January 2008 to October 2017, 41 of 254 patients with end-stage HAE fulfilled the inclusion criteria (ERAT group, n=35; allotransplantation group, n=6). Each group was assessed for indications and short- and long-term outcomes. RESULTS: The intraoperative mortality was zero in both groups. Two patients died after ERAT due to intra-abdominal bleeding and acute cerebral hemorrhage. The most frequent postoperative complications were biliary complications, which occurred in six patients (14.6%). Parasite recurrence was recorded in two patients, at 16 months and 52 months after allotransplantation. The survival curve showed a longer survival time in the ERAT group than in the allotransplantation group (P=0.028). In the ERAT group, the 1-, 3-, and 5-year overall survival rates were all 100%. In the allotransplantation group, the 1-, 3-, and 5-year overall survival rates were 100%, 83.3%, and 66.7%, respectively. CONCLUSIONS: This appears to be the first series comparing ERAT with allotransplantation for end-stage HAE. ERAT may be a superior alternative to allotransplantation in some cases, as it requires neither an organ donor nor immunosuppressive therapy.