The structural and electronic properties of (001) surface of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) with first-principles calculations.

CONTEXT: 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) is a typical insensitive energetic material. It can be used in explosive formulations, such as PBX-9502 and LX-17-0. TATB is an intriguing and unusual explosive for another reason: it crystallizes into a wide array of planar hydrogen bonds, forming a graphite-like layered structure. Therefore, TATB is one of the important research objects, and its surface structure needs to be deeply understood. In this research work, the electronic and energetic properties of TATB (001) surface are explored. METHODS: In this paper, the structural, electronic, energetic properties and impact sensitivity of TATB (001) surface structure at 0 and -3 GPa along with x-axis were calculated in this study using the first-principles calculations. The calculations in this paper are performed in the CASTEP code, which is based on the density functional theory with the first-principles calculation method using the plan-wave pseudopotential approach. The exchange-correlation interaction was adopted by the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) functional. The DFT-D method with the Grimme correction accurately models van der Waals interactions. To model the surface structures of TATB, the planar slab method was employed. We constructed TATB (001) periodic slabs including three layers with a 15-Å vacuum layer.

Exploring the Aroma Fingerprint of Various Chinese Pear Cultivars through Qualitative and Quantitative Analysis of Volatile Compounds Using HS-SPME and GC×GC-TOFMS.

To comprehensively understand the volatile compounds and assess the aroma profiles of different types of Pyrus ussuriensis Maxim. Anli, Dongmili, Huagai, Jianbali, Jingbaili, Jinxiangshui, and Nanguoli were detected via headspace solid phase microextraction (HS-SPME) coupled with two-dimensional gas chromatography/time-of-flight mass spectrometry (GC×GC-TOFMS). The aroma composition, total aroma content, proportion and number of different aroma types, and the relative quantities of each compound were analyzed and evaluated. The results showed that 174 volatile aroma compounds were detected in various cultivars, mainly including esters, alcohols, aldehydes, and alkenes: Jinxiangshui had the highest total aroma content at 2825.59 ng/g; and Nanguoli had the highest number of aroma species detected at 108. The aroma composition and content varied among pear varieties, and the pears could be divided into three groups based on principal component analysis. Twenty-four kinds of aroma scents were detected; among them, fruit and aliphatic were the main fragrance types. The proportions of aroma types also varied among different varieties, visually and quantitatively displaying changes of the whole aroma of the different varieties of pears brought by the changes in aroma composition. This study contributes to further research on volatile compound analysis, and provides useful data for the improvement of fruit sensory quality and breeding work.

Deubiquitinase CYLD regulates excitatory synaptic transmission and short-term plasticity in the hippocampus.

The fate of proteins is determined by the addition of various forms of polyubiquitin during ubiquitin-mediated proteasomal degradation. Cylindromatosis (CYLD), a K63-specific deubiquitinase, is enriched in postsynaptic density fractions of the rodent central nervous system (CNS), but the synaptic role of CYLD in the CNS is poorly understand. Here we show that CYLD deficiency (Cyld-/-) results in reduced intrinsic hippocampal neuronal firing, a decrease in the frequency of spontaneous excitatory postsynaptic currents and a decrease in the amplitude of field excitatory postsynaptic potentials. Moreover, Cyld-/- hippocampus shows downregulated levels of presynaptic vesicular glutamate transporter 1 (vGlut1) and upregulated levels of postsynaptic GluA1, a subunit of the AMPA receptor, together with an altered paired-pulse ratio (PPR). We also found increased activation of astrocytes and microglia in the hippocampus of Cyld-/- mice. The present study suggests a critical role for CYLD in mediating hippocampal neuronal and synaptic activity.

Application of Metal-Organic Frameworks (MOFs) in Environmental Biosystems.

Metal-organic frameworks (MOFs) are crystalline materials that are formed by self-assembling organic linkers and metal ions with large specific areas and pore volumes. Their chemical tunability, structural diversity, and tailor-ability make them adaptive to decorate many substrate materials, such as biomass-derived carbon materials, and competitive in many environmental biosystems, such as biofuel cells, bioelectrocatalysts, microbial metal reduction, and fermentation systems. In this review, we surmised the recent progress of MOFs and MOF-derived materials and their applications in environmental biosystems. The behavior of MOFs and MOF-derived materials in different environmental biosystems and their influences on performance are described. The inherent mechanisms will guide the rational design of MOF-related materials and lead to a better understanding of their interaction with biocomponents.

Theoretical study on the vibrational spectra and potential energy curves for SiC (X3Π) and SiS (X1Σ+) molecules.

In this work, the vibrational constants (ωe,ωexe) calculated by the variational algebraic method (VAM) and some other molecular constants (De,re,Be,αe) were used to construct the improved Hulburt-Hirschfelder (IHH) analytical potential energy function (APEF). Not only that, but the calculated VAM potential points are used as the 'true' energies to determine the value of the variational parameter λ which is the pivotal fitting parameter in the IHH potential. With limited experimental data, high-precision IHH potential can be achieved by combining the VAM and the IHH APEF. This combination of the VAM and the IHH APEF is referred to be VAIHH APEF, which is employed to study the vibrational energies and potential energy curves (PECs) of SiC (X3Π) and SiS (X1Σ+) molecules, yielding full vibrational spectra and spectroscopic constants. The calculational results indicate that the VAIHH APEFs of SiC (X3Π) and SiS (X1Σ+) molecules are in good agreement with the experimental RKR potential points. Accurate PECs of SiC (X3Π) and SiS (X1Σ+) molecules imply that the VAIHH APEF is of high quality.

Dual-mode microstrip leaky-wave antenna for pattern diversity application.

We present a dual-mode microstrip leaky-wave antenna (LWA), which is characterized by radiating a single beam or dual symmetrical beam. Different from the conventional single-mode microstrip LWA, the designed antenna is based on the odd mode and the even mode of the employed shorted microstrip line. The working principle of these two modes is fully studied by analyzing the electric-field distributions and their dispersion curves. Additionally, it can be found that the odd mode and the even mode are capable of realizing different radiation patterns. Furthermore, a mode translator is particularly designed in order to efficiently excite the concerned two modes. Finally, the presented antenna is simulated, fabricated, and measured, and the simulated results agree well with the measurements. The tested far-field results show that the designed dual-mode LWA realized single-beam scanning from 39° to 64° when the frequency ranges from 4.5 to 5.0 GHz and dual symmetrical beam scanning from 44° to 60° as the frequency varies from 4.5 to 4.9 GHz, respectively.

A Novel Auto-Synthesis Dataset Approach for Fitting Recognition Using Prior Series Data.

To address power transmission line (PTL) traversing complex environments leading to data collection being difficult and costly, we propose a novel auto-synthesis dataset approach for fitting recognition using prior series data. The approach mainly includes three steps: (1) formulates synthesis rules by the prior series data; (2) renders 2D images based on the synthesis rules utilizing advanced virtual 3D techniques; (3) generates the synthetic dataset with images and annotations obtained by processing images using the OpenCV. The trained model using the synthetic dataset was tested by the real dataset (including images and annotations) with a mean average precision (mAP) of 0.98, verifying the feasibility and effectiveness of the proposed approach. The recognition accuracy by the test is comparable with training by real samples and the cost is greatly reduced to generate synthetic datasets. The proposed approach improves the efficiency of establishing a dataset, providing a training data basis for deep learning (DL) of fitting recognition.

Selective and sensitive detection and detoxification of Pd2+ in living cells with a water-soluble fluorescent probe.

Due to the cytotoxic potential of even low doses of Pd2+, the development of its detection and detoxification strategies is highly demanding. In this paper, we developed a water-soluble fluorescent probe IMQU-8 with a new scaffold for Pd2+ sensing. IMQU-8 can detect Pd2+ with high selectivity and sensitivity and has a good detection limit of 2.5 nM under physiological conditions. Its sensing mechanism has been revealed through job plot experiments and HRMS, FT-IR, 1H NMR and DFT calculations, which demonstrated that the N atoms of the pyridyl group and imino group are crucial for Pd2+ sensing. Fluorescence lifetime assessment indicated that IMQU-8 and IMQU-8-Pd have almost identical fluorescence lifetimes, implying that IMQU-8 undergoes static quenching toward Pd2+. Additionally, IMQU-8 has been successfully applied to image Pd2+ in living cells. Since IMQU-8 and its coordinated complex IMQU-8-Pd exhibit low toxicity, IMQU-8 has been applied for the detoxification of Pd2+ in living cells.

Acceleration Effect of Bases on Mn Pincer Complex-Catalyzed CO2 Hydroboration.

Herein, we report a comprehensive study of CO2 hydroboration catalyzed by Mn pincer complexes. The traditional metal-ligand cooperation (MLC) mechanism based on the H-Mn-N-Bpin pincer complex is not viable due to the competing abstraction of the Bpin group from the H-Mn-N-Bpin complex by NaOtBu. Instead, we propose an ionic mechanism based on the H-Mn-N-Na species with a low energy span (22.5 kcal/mol) and unveil the acceleration effect of bases. The X groups in the H-Mn-N-X catalyst models are further modulated, and the steric hindrance and H→B donor-acceptor interactions of the X group increase the energy barrier of the hydride transfer. The hydrogen bond and electrostatic interactions of the X group can accelerate the hydride transfer to HCOOBpin and HCHO molecules except for the nonpolar CO2 molecule. Based on these discoveries, we designed a pyridine-based Mn pincer catalyst system, which could achieve CO2 hydroboration in low-temperature and base-free conditions through a metal-ligand cooperation mechanism.

Novel combination of bioleaching and persulfate for the removal of heavy metals from metallurgical industry sludge.

The objective of this study was to remove heavy metals from metallurgical industry sludge by bioleaching alone and bioleaching combined with persulfate (PDS). The results showed that the removal of Cu, Zn, Pb, and Mn reached 70%, 83.8%, 25.2%, and 76.9% by bioleaching alone after 18 days, respectively. The experiment of bioleaching combined with PDS was carried out in which the optimal additive dosage of K2S2O8, 8 g/L, was added to bioleaching after 6 d. After 1 h, the removal of four heavy metals reached 75.1, 84.3, 36.7, and 81.6%, respectively. Compared with bioleaching alone, although the increase in removal efficiency was only slightly increased, the treatment cycle was distinctly shortened from 18 to 6 days + 1 h. The scanning electron microscopy (SEM) results showed that the surface morphology of the sludge was changed significantly by the combined treatment. The content of heavy metals was significantly reduced after bioleaching combined with PDS by energy dispersive X-ray spectroscopy (EDX). Through electron paramagnetic resonance (EPR) and free radical quenching experiments, it was indicated that sulfate radicals [Formula: see text] plays a leading role in the combined treatment. The treated sludge mainly existed in a stable form, and the bioavailability was reduced with European Community Bureau of Reference (BCR) morphology analysis. This study proved that the combination of bioleaching and PDS could not only shorten the treatment cycle but also further improve the efficiency of heavy metal leaching. It provides a novel treatment method for the removal of heavy metals from metallurgical industry sludge.

Substituent, Solvent, and Dispersion Effects on the Zwitterionic Character and Dimerization Thermochemistry of the Group 6 Fulvene Metal Tricarbonyl Complexes.

Dimerizations of fulvene metal tricarbonyl complexes of the type (C5H4CRR')M(CO)3 (R, R' = MeO, Me, H; M = Cr, Mo, W) to form a metal-metal bond and a new carbon-carbon bond, thereby giving binuclear cyclopentadienyl metal carbonyl derivatives, are predicted to be thermochemically favored but to have significant activation energies ranging from ΔE = 19 to 42 kcal/mol. However, the introduction of dimethylamino but not methoxy substituents onto the exocyclic carbon atom changes the situation drastically so that the monomers [C5H4CH(NMe2)]M(CO)3 and [C5H4C(NMe2)2]M(CO)3 become strongly thermochemically favored, lying ΔE = 43 kcal/mol (M = W) to 63 kcal/mol (M = Cr) below their corresponding dimers. In such dimethylamino-substituted (fulvene)M(CO)3 derivatives, the M-C distance to the exocyclic fulvene carbon is lengthened beyond the bonding distance to give a zwitterionic structure with a pentahapto fulvene ligand. Such M-C distances in (fulvene)M(CO)3 complexes, which have preferred zwitterionic structures, increase with increasing solvent polarity (i.e., dielectric constant) until a saturation point is reached.

A data- and model-driven strategy for the evaluation of the experimental transition lines: Theoretical prediction for the ground state of 12C16O.

An analytical formula that relates the molecular constants of the Herzberg expression and experimental transition lines is developed herein with a difference algebraic approach (DAA) model. Based on the data-driven strategy, the DAA model is able to deal with the tiny uncertainties that exhibit behind the experimental transition lines, which is applied to the P branch emission spectra of some first overtone bands of the ground electronic state of 12C16O. The relationship can be used to generate transition lines with sufficient accuracy, as evident from the high J of agreement with the HITRAN database, Velichko data, Goorvitch data and quantum-mechanical data. In addition, line intensities, absorption oscillator strengths and Einstein A coefficients of these lines, which are introduced to enhance the dataset and are in good agreement with those of other authors, are also reported to validate our results. These various comparative results show that the proposed data-driven strategy based on the DAA model is expecting to be a good algorithm that relies on relatively limited data for training.

A method for predicting the molar heat capacities of HBr and HCl gases based on the full set of molecular rovibrational energies.

A new method is presented for one to obtain the molar heat capacities of diatomic macroscopic gas with a full set of microscopic molecular rovibrational energies. Based on an accurate experimental vibrational energies subset of a diatomic electronic ground state, the full vibrational energies can be obtained by using the variational algebraic method (VAM), the potential energy curves (PECs) will be constructed by the Rydberg-Klein-Rees (RKR) method, the full set of rovibrational energies will be calculated by the LEVEL program, and then the partition functions and the molar heat capacities of macroscopic gas can be calculated with the help of the quantum statistical ensemble theory. Applying the method to the ground state HBr and HCl gases, it is found that the relative errors of the partition functions calculated in the temperature range of 300 âˆ¼ 6000 K are in excellent agreement with those obtained from TIPS database, and the calculated molar heat capacities are closer to the experimental values than those calculated by other methods without considering the energy levels of highly excited quantum states. The present method provides an effective new way for one to obtain the full set of molecular rovibrational energies and the molar heat capacities of macroscopic gas through the microscopic spectral information of a diatomic system.

Systemic LPS-induced microglial activation results in increased GABAergic tone: A mechanism of protection against neuroinflammation in the medial prefrontal cortex in mice.

Neuroinflammation with excess microglial activation and synaptic dysfunction are early symptoms of most neurological diseases. However, how microglia-associated neuroinflammation regulates synaptic activity remains obscure. We report here that acute neuroinflammation induced by intraperitoneal injection of lipopolysaccharide (LPS) results in cell-type-specific increases in inhibitory postsynaptic currents in the glutamatergic, but not the GABAergic, neurons of medial prefrontal cortex (mPFC), coinciding with excessive microglial activation. LPS causes upregulation in levels of GABAAR subunits, glutamine synthetase and vesicular GABA transporter, and downregulation in brain-derived neurotrophic factor (BDNF) and its receptor, pTrkB. Blockage of microglial activation by minocycline ameliorates LPS-induced abnormal expression of GABA signaling-related proteins and activity of synaptic and network. Moreover, minocycline prevents the mice from LPS-induced aberrant behavior, such as a reduction in total distance and time spent in the centre in the open field test; decreases in entries into the open arm of elevated-plus maze and in consumption of sucrose; increased immobility in the tail suspension test. Furthermore, upregulation of GABA signaling by tiagabine also prevents LPS-induced microglial activation and aberrant behavior. This study illustrates a mode of bidirectional constitutive signaling between the neural and immune compartments of the brain, and suggests that the mPFC is an important area for brain-immune system communication. Moreover, the present study highlights GABAergic signaling as a key therapeutic target for mitigating neuroinflammation-induced abnormal synaptic activity in the mPFC, together with the associated behavioral abnormalities.

Advances in Surface-Enhanced Raman Scattering-Based Aptasensors for Food Safety Detection.

Owing to the excellent performances of high sensitivity, high specificity, on-site detection, and multiplexing capability, surface-enhanced Raman scattering (SERS)-based aptasensors have performed prosperous applications and gained impressive progress in food safety. Herein, we reviewed the SERS-based aptasensors from the principles to specific applications in food safety. First, the sensor-working principles, SERS label design and preparation are introduced. Then, the popular platforms in the aptasensors are summarized with their advantages and disadvantages, followed by their representative applications. Further, the specific applications of developing SERS-based aptasensors in food safety are systematically provided. Moreover, the multiplex analysis using SERS labels are highlighted. Finally, challenges and perspectives for improving the SERS-based aptasensor performance are also discussed, aiming to give some proposes for researchers to choose suitable SERS-based aptasensors according to specific applications.

Deficiency of the CYLD Impairs Fear Memory of Mice and Disrupts Neuronal Activity and Synaptic Transmission in the Basolateral Amygdala.

Fear learning and memory are crucial for animal survival. Abnormal fear memory is a hallmark of many neuropsychiatric disorders. Appropriate neuronal activation and excitability in the basolateral amygdala (BLA) are necessary for the formation of fear memory. The gene cylindromatosis (Cyld), which encodes a lysine-63 deubiquitinase, is expressed in several brain regions including the amygdala. The functions of the cylindromatosis protein (CYLD) in the regulation of the neuronal activity, neural circuits and fear memory, remain largely unknown, however. Here, we report that Cyld knockout impairs amygdala-dependent tone-cued fear memory. The number of c-Fos+ neurons responding to the tone-cued fear test was reduced in the BLA of Cyld -/- mice, suggesting that the absence of CYLD causes aberrant neuronal activation. We found that this aberrant neuronal activation in the BLA of Cyld -/- mice may relate to the decreased excitability of principal neurons. Another possibility of aberrant neuronal activation could be the impaired excitatory synaptic transmission in the BLA of Cyld -/- mice. Specifically, both the frequency of spontaneous excitatory postsynaptic currents and the amplitude of miniature excitatory postsynaptic currents in BLA principal neurons were decreased. In addition, Cyld mutation caused an increase in both the frequency of miniature inhibitory postsynaptic currents in principal neurons and the number of parvalbumin+ interneurons, consistent with excessive local circuit inhibition in the BLA of Cyld -/- mice. Taken together, these results suggest that CYLD deficiency disrupts the neuronal activity and synaptic transmission in the BLA of mice which may contribute to the impaired fear memory observed in Cyld -/- mice.

A Frequency-Programmable Miniaturized Radio Frequency Transmitter for Animal Tracking.

In animal tracking applications, smaller transmitters can reduce the impact of the transmitter on the tagged animal and thus provide more accurate data about animal behavior. By combining a novel circuit design and a newly developed micro-battery, we developed frequency-programmable and more powerful radio frequency transmitters that are about 40% smaller and lighter in weight than the smallest commercial counterpart for animal monitoring at the time of development. The new radio frequency transmitter has a miniaturized form factor for studying small animals. Designs of two coding schemes were developed: one transmits unmodulated signals (weight: 152 mg; dimensions: Ø 2.95 mm × 11.22 mm), and the other transmits modulated signals (weight: 160 mg; dimensions: Ø 2.95 mm × 11.85 mm). To accommodate different transmitter life requirements, each design can be configured to transmit in high or low signal strength. Prototypes of these transmitters were evaluated in the laboratory and exhibited comparable or longer service life and higher signal strength compared to their smallest commercial counterparts.

MicroRNAs in Fetal Umbilical Cord Blood as a Prenatal Screening Tool for Congenital Heart Disease.

OBJECTIVE: MicroRNAs (miRNAs) have been used as molecular markers for various diseases. This study aimed to evaluate the predicted performance of miRNAs in fetal umbilical cord blood for detecting congenital heart disease (CHD). METHODS: In this retrospective cohort study, a total of 60 pregnant women (involving 30 fetuses with CHD and 30 normal fetuses requiring induction of labor) were included. Umbilical cord blood was collected for miRNA measurement. Expression levels of the miRNAs were detected by qRT-PCR. The predictive accuracy of miRNA was assessed by constructing a receiver operating characteristic (ROC) curve and evaluated by calculating the area under the curve (AUC). The point biserial correlation coefficient (PBCC) was analyzed to evaluate the correlation of miRNA with CHD. RESULTS: The CHD group and control group were well-balanced in age, gravidity, and parity. miRNA-133 was not detected in all subjects. Subjects with CHD fetuses had significantly lower levels of miRNA-1, miRNA-208, and miRNA-499. Different types of CHD showed different variation trends of miRNA expression. Correlation analysis showed that expression levels of miRNA-1, miRNA-208, and miRNA-499 were negatively correlated with the occurrence of CHD, with a PBCC of -0.65, -0.47, and -0.60, respectively. miRNA-1, miRNA-208, and miRNA-499 displayed an AUC of 0.86 (95% CI, 0.76-0.96; p<0.001), 0.75 (95% CI, 0.63-0.87; p=0.009), and 0.84 (95% CI, 0.74-0.95; p<0.001), respectively, for discriminating CHD from normal fetuses, with cut-off values of 0.795, 0.835, and 0.795, respectively. CONCLUSION: The expression levels of miRNA-1, miRNA-208, and miRNA-499 in umbilical cord blood may be useful for predicting fetal CHD. The findings indicated that miRNAs have the potential to be a prenatal screening tool in the early diagnosis of CHD.

Cattail fibers as source of cellulose to prepare a novel type of composite aerogel adsorbent for the removal of enrofloxacin in wastewater.

In this study, cattail was researched as a natural cellulose source to extract cellulose. Dewaxing, alkali and bleaching treatments were carried out for the cattail fibers (CFs). The FTIR, SEM and XRD results indicated that hemicellulose and lignin were successfully removed from the CFs, and the content of cattail cellulose increased from 41.66 ± 1.11% to 89.72 ± 1.07%. Subsequently, cellulose aerogel was prepared by the extracted cattail cellulose. The Zeolitic imidazolate framework-8 (ZIF-8) was uniformly loaded onto the surface of cellulose aerogel by the in situ growth, and ZIF-8 Cattail Cellulose Aerogel (ZCCA) was finally prepared. The SEM, FTIR, XRD and TGA results further confirmed the successful preparation of ZCCA. Additionally, the results of the adsorption experiment showed that ZCCA had excellent adsorption performance for enrofloxacin, and the maximum adsorption capacity of enrofloxacin reached 172.09 mg·g-1 while showing good reusability. The adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic studies showed that the adsorption of enrofloxacin was a spontaneous endothermic reaction and that the adsorption mechanism involves the interaction of hydrogen bonds, electrostatic and π-π stacking.

Synthesis of Methanesulfonic Acid Directly from Methane: The Cation Mechanism or the Radical Mechanism?

In 2019, Diaz-Urrutia and Ott developed a high-yield method for direct conversion of methane to methanesulfonic acid and proposed a cationic chain reaction mechanism. However, Roytman and Singleton questioned this mechanism, and they favored a free-radical mechanism. In the present paper, we studied both the cationic chain and radical mechanisms and found the radical mechanism is more favorable, since it has a much lower energy barrier. However, the radical mechanism has not considered the effect of ions for the reaction taking place in oleum. Thus, we studied a simple model of a protonated radical mechanism, which further lowers the energy barrier. Although the true mechanism for the CH4 + SO3 reaction could be more complicated in electrolyte solutions, this model should be helpful for the further study of the mechanism of this reaction.