Spectroscopic snapshot for neutral water nonamer (H2O)9: Adding a H2O onto a hydrogen bond-unbroken edge of (H2O)8.

Structural characterization of neutral water clusters is crucial to understanding the structures and properties of water, but it has been proven to be a challenging experimental target due to the difficulty in size selection. Here, we report the size-specific infrared spectra of confinement-free neutral water nonamer (H2O)9 based on threshold photoionization, using a tunable vacuum ultraviolet free-electron laser. Distinct OH stretch vibrational fundamentals in the 3200-3350 cm-1 region are observed, providing unique spectral signatures for the formation of an unprecedented (H2O)9 structure evolved by adding a ninth water molecule onto a hydrogen bond-unbroken edge of the (H2O)8 octamer with D2d symmetry. This nonamer structure coexists with the five previously identified structures that can be viewed as derived by inserting a ninth water molecule into a hydrogen bond-broken edge of the D2d/S4 octamer. These findings provide key microscopic information for systematic understanding of the formation and growth mechanism of dynamical hydrogen-bonding networks that are responsible for the structure and properties of condensed-phase water.

Approaching a Minimal Topological Electronic Structure in Antiferromagnetic Topological Insulator MnBi2Te4 via Surface Modification.

The topological electronic structure plays a central role in the nontrivial physical properties in topological quantum materials. A minimal, "hydrogen-atom-like" topological electronic structure is desired for research. In this work, we demonstrate an effort toward the realization of such a system in the intrinsic magnetic topological insulator MnBi2Te4, by manipulating the topological surface state (TSS) via surface modification. Using high resolution laser- and synchrotron-based angle-resolved photoemission spectroscopy (ARPES), we found the TSS in MnBi2Te4 is heavily hybridized with a trivial Rashba-type surface state (RSS), which could be efficiently removed by the in situ surface potassium (K) dosing. By employing multiple experimental methods to characterize K dosed surface, we attribute such a modification to the electrochemical reactions of K clusters on the surface. Our work not only gives a clear band assignment in MnBi2Te4 but also provides possible new routes in accentuating the topological behavior in the magnetic topological quantum materials.

Observation of Confinement-Free Neutral Group Three Transition Metal Carbonyls Sc(CO)7 and TM(CO)8 (TM=Y, La).

Spectroscopic characterization of neutral highly-coordinated compounds is essential in fundamental and applied research, but has been proven to be a challenging experimental target because of the difficulty in mass selection. Here, we report the preparation and size-specific infrared-vacuum ultraviolet (IR-VUV) spectroscopic identification of group-3 transition metal carbonyls Sc(CO)7 and TM(CO)8 (TM=Y, La) in the gas phase, which are the first confinement-free neutral heptacarbonyl and octacarbonyl complexes. The results indicate that Sc(CO)7 has a C2v structure and TM(CO)8 (TM=Y, La) have a D4h structure. Theoretical calculations predict that the formation of Sc(CO)7 and TM(CO)8 (TM=Y, La) is both thermodynamically exothermic and kinetically facile in the gas phase. These highly-coordinated carbonyls are 17-electron complexes when only those valence electrons that occupy metal-CO bonding orbitals are considered, in which the ligand-only 4b1u molecular orbital is ignored. This work opens new avenues toward the design and chemical control of a large variety of compounds with unique structures and properties.

Ligand-Induced Tuning of the Electronic Structure of Rhombus Tetraboron Cluster.

A neutral boron carbonyl complex B4 (CO)3 is generated in the gas phase and is characterized by infrared plus vacuum ultraviolet (IR+VUV) two-color ionization spectroscopy and quantum chemical calculations. The complex is identified to have a planar C2v structure with three CO ligands terminally coordinated to a rhombus B4 core. It has a closed-shell singlet ground state that correlates to an excited state of B4 . Bonding analyses on B4 (CO)3 as well as the previously reported B4 and B4 (CO)2 indicate that the electronic structure of rhombus tetraboron cluster changes from a close-shell singlet to an open-shell singlet in B4 (CO)2 and to a close-shell singlet in B4 (CO)3 , demonstrating that the electronic structures of boron clusters can be effectively tuned via sequential CO ligand coordination.

Atmospheric particle-bound polycyclic aromatic compounds over two distinct sites in Pakistan: Characteristics, sources and health risk assessment.

Much attention is drawn to polycyclic aromatic hydrocarbons (PAHs) as an air pollutant due to their toxic, mutagenic and carcinogenic properties. Therefore, to understand the levels, seasonality, sources and potential health risk of PAHs in two distinct geographical locations at Karachi and Mardan in Pakistan, total suspended particle (TSP) samples were collected for over one year period. The average total PAH concentrations were 31.5 ± 24.4 and 199 ± 229 ng/m3 in Karachi and Mardan, respectively. The significantly lower concentration in Karachi was attributed to diffusion and dilution of the PAHs by the influence of clean air mass from the Arabian sea and high temperature, enhancing the volatilization of the particle phase PAHs to the gas phase. Conversely, the higher concentration (~6 times) in Mardan was due to large influence from local and regional emission sources. A clear seasonality was observed at both the sites, with the higher values in winter and post-monsoon due to higher emissions and less scavenging, and lower values during monsoon season due to the dilution effect. Diagnostic ratios and principal component analysis indicated that PAHs in both sites originated from traffic and mixed combustion sources (fossil fuels and biomass). The average total BaP equivalent concentrations (BaPeq) in Karachi and Mardan were 3.26 and 34 ng/m3, respectively, which were much higher than the WHO guideline of 1 ng/m3. The average estimates of incremental lifetime cancer risk from exposure to airborne BaPeq via inhalation indicated a risk to human health from atmospheric PAHs at both sites.

Photoelectron Velocity Map Imaging Spectroscopic and Theoretical Study of Heteronuclear MNi(CO)7- (M = V, Nb, Ta).

A series of heteronuclear group 5 metal-nickel carbonyls MNi(CO)7- (M = V, Nb, Ta) have been generated via a laser ablation ion source and studied by photoelectron velocity-map imaging spectroscopy. Quantum chemical calculations have been performed to probe the electronic and geometric structures and help to assign the spectra. The adiabatic detachment energies (ADEs) and vertical detachment energies (VDEs) are deduced from spectra to be 3.40/3.58, 3.34/3.55, 3.30/3.50 eV, which are consistent with quantum chemical computational results. The MNi(CO)7- (M = V, Nb, Ta) consists of three bridging carbonyls, one carbonyl terminally bonded to the Ni atom and three carbonyls terminally bonded to the M (M = V, Nb, Ta) atom. These geometries are different from homobinuclear Cr2(CO)7+, Ni2(CO)7+, Pd2(CO)7+, and Fe2(CO)7- and heterobinuclear CuFe(CO)7-, CoZn(CO)7+, and CO is largely activated by a bridging coordination mode. The experimental and theoretical results would provide important information to understand the chemisorbed CO molecules on alloy surfaces or interfaces, which is of great significance to elucidate CO molecule activation processes.

Dynamic changes of lipid profile in severe hypertriglyceridemia-induced acute pancreatitis patients under double filtration plasmapheresis: a retrospective observational study.

BACKGROUND: To investigate the dynamic change of lipid profile under double filtration plasmapheresis (DFPP) in severe hypertriglyceridemia-induced acute pancreatitis (sHTGP) patients and ascertain the association between these changes and the clinical prognosis. METHODS: sHTGP patients admitted within 72 h after disease onset were included, and all the patients received DFPP within 24 h after admission. Lipid profile were detected on admission, consecutive 4 days after DFPP and at discharge. RESULTS: There were 47 sHTGP patients enrolled in this study. At admission, all the parameters of lipid profile changed significantly except for low density lipoprotein. In the first day after DFPP, the serum level of TG, cholesterol and very low density lipoprotein declined significantly, while the high-density lipoprotein (HDL) as well as apoprotein A1 elevated obviously (P < 0.05). TG maintained the downward trend in the following three days and the other parameters kept steady. Linear regression analysis showed that HDL was negatively correlated with the duration of hospitalization among three adjusted models (P = 0.043, P = 0.029, P = 0.025 respectively). CONCLUSION: There was distinct fluctuation of the lipid profile upon the burst of sHTGP and the parameters changed significantly in the first day after DFPP. Among these parameters, HDL may serve as a biomarker for disease prognosis in patients with sHTGP.

Elevated triglycerides on admission positively correlate with the severity of hypertriglyceridaemic pancreatitis.

BACKGROUND: Hypertriglycaeridemia has been positively associated with the risk of acute pancreatitis, but whether increased triglyceride (TG) levels are related to the severity of pancreatitis remains unclear. The aim of this study was to assess the relationship between hyperlipidaemia and disease severity of hypertriglycaeridemic pancreatitis. METHODS: From 2016 to 2018, patients with hypertriglyceridaemic pancreatitis presented within 24 hours from symptom onset were retrospectively enrolled. The severity was classified by the Atlanta classification 2012. The demographic and clinical characteristics of patients were compared with respect to severity stratification and different TG categories, respectively. The relationships of admission TG levels and disease severity were assessed with Spearman's rank correlation test and Linear-by-Linear Association test. RESULTS: Among 256 patients included, 125 (48.8%) were diagnosed with mild (MAP), 76 (29.7%) with moderate (MSAP) and 55 (21.5%) with severe acute pancreatitis (SAP). The mean TGs (standard derivation) on admission in patients with MAP, MSAP and SAP were 21.6 (15.2) mmol/L (1913 [1346] mg/dL), 34.6 (22.6) mmol/L (3065 [2002] mg/dL) and 41.5 (32.5) mmol/L (3676 [2879] mg/dL), respectively (P < .001). Patients were then categorised based on their TG levels. TG categories had a strong positive correlation with the disease severity (Rho = 0.34, P < .001). Positive trend for the association across increasing TG categories and SAP was observed (P < .001). CONCLUSIONS: Elevated serum TG levels at the time of admission seem to correlate positively with the severity of hypertriglyceridaemia-induced acute pancreatitis.

Structures and Infrared Spectra of [M(CO2)7]+ (M = V, Cr, and Mn) Complexes.

Gas-phase infrared photodissociation spectra of [V(CO2) n]+ complexes revealed three new vibrational bands at 1140, 1800, and 3008 cm-1 at n = 7, the features of which are retained in the larger clusters (Ricks, A. M.; Brathwaite, A. D.; Duncan, M. A. J. Phys. Chem. A 2013, 117, 11490-11498). However, structural assignment of this intriguing feature remains open. Herein, quantum chemical calculations on [V(CO2)7]+ were carried out to identify the structure of the low-lying isomers and to assign the observed spectral features. The comparison of calculated infrared spectra of [V(CO2)7]+ with experimental infrared spectra identified the formation of a bent CO2- species, suggesting the ligand-induced activation of CO2 by the vanadium cation. The structures and infrared spectra of [Cr(CO2)7]+ and [Mn(CO2)7]+ were also predicted and discussed.

Infrared Spectroscopy of Hydrogen-Bonding Interactions in Neutral Dimethylamine-Methanol Complexes.

Infrared spectra of the neutral dimethylamine-methanol cluster, DMA-CH3OH, were measured in the spectral range of 2800-3900 cm-1 using an infrared-vacuum ultraviolet (IR-VUV) scheme. Quantum chemical calculations and ab initio molecular dynamic (AIMD) simulations were carried out to understand the experimental spectral features. Experimental and theoretical results reveal the coexistence of N···HO and O···HN hydrogen-bonded structures. AIMD simulations show that the methyl group in methanol internally rotates around the N···O axis, addressing the dynamic effect of the fluctuation of hydrogen bonds on the vibrational features. The bonding analysis was performed to elucidate the nature of the intermolecular interaction between DMA and CH3OH. The present work provides the fundamental understanding of hydrogen-bonding networks in the amine-alcohol complexes.

N-3 polyunsaturated fatty acid-enriched lipid emulsion improves Paneth cell function via the IL-22/Stat3 pathway in a mouse model of total parenteral nutrition.

Total parenteral nutrition (TPN) is a life-saving therapy for patients with gastrointestinal dysfunction or failure. Long-term TPN impairs gut barrier function and contributes to infections and poor clinical outcomes. However, the underlying mechanisms of TPN-related gut barrier damage have not been fully elucidated, and effective measures are still rare. Here, we compared the effects of a predominantly n-6 polyunsaturated fatty acids emulsion (PUFAs; Intralipid) and a lipid emulsion containing n-3 PUFAs (Intralipid plus Omegaven) on antimicrobial peptides produced by Paneth cells. Our results show for the first time that n-3 PUFAs markedly ameliorated intestine atrophy, and increased protein levels of lysozyme, RegIIIγ, and α-cryptdin 5, and their mRNA expression, compared to the n-6 PUFAs emulsion. Importantly, our study reveals that downregulation of IL-22 and phosphorylated Stat3 (p-Stat3) is associated with Paneth cell dysfunction, which may mediate TPN-related gut barrier damage. Lastly, n-3 PUFAs upregulated levels of IL-22 and increased the p-Stat3/Stat3 ratio in ileal tissue, suggesting that n-3 PUFAs improve Paneth cell function through activation of the IL-22/Stat3 pathway. Therefore, our study provides a cogent explanation for the beneficial effects of n-3 PUFAs, and indicates the IL-22/Stat3 pathway as a promising target in the treatment of TPN-related gut barrier damage.

Nutrition Status, Nutrition Support Therapy, and Food Intake are Related to Prolonged Hospital Stays in China: Results from the NutritionDay 2015 Survey.

BACKGROUND AND AIMS: Malnutrition is a common and critical problem that greatly influences the clinical outcomes of hospitalized patients. Nutrition support therapy and food intake, in addition to disease-related factors, are also important to maintain the nutrition status of patients. In light of this, we aimed to examine the risk factors associated with malnutrition in 3 hospitals in China. METHODS: This project was part of the NutritionDay audit, an international daylong cross-sectional audit investigating the nutritional intervention profiles of hospitalized patients. Seven standardized questionnaires were used, and malnutrition was defined as a body mass index <18.5 kg/m2 or unintentional weight loss >5% in last 3 months. RESULTS: A total of 842 hospitalized patients from 9 units in 3 Chinese hospitals participated in the project on November 19, 2015. Among them, 825 were included in the analyses. Malnutrition was identified in 29.3% of the patients and oral nutrition was the primary nutrition support therapy administered (n = 623, 75.6%). Age, nutrition support, and food intake during the past week were independent risk factors for malnutrition. Furthermore, nutrition status, nutrition support therapy, and food intake during the past week were associated with prolonged length of stay. CONCLUSIONS: The prevalence of malnutrition in Chinese hospitals was similar to that in European hospitals. Nutrition status was associated with age, nutrition support, and food intake, which was closely related to patients' clinical outcome, such as prolonged hospital stays as confirmed in this study. More studies are needed to determine why nutrition intake is often inadequate and to determine efficient methods for correcting the nutrition status of patients.

A new mouse model of depression induced by chronic restraint stress combined with lipopolysaccharide.

The aim of this study was to establish a multi-factor-induced depression model in mice within a relatively short period, specifically through the combination of intraperitoneal injection of lipopolysaccharide (LPS) and chronic restraint stress (CRS), and to evaluate the differences in depressive-like behaviors among three different strains of mice, seeking mouse strains more suitable for this combined model. The mice of each strain were randomly divided into the normal group and model group. The mice in the model group received a single intraperitoneal injection of LPS once daily (1 mg/kg/d for 7 days) and subsequent CRS for 6 h, to induce depression, while the mice in the normal group received no treatment. Behavioral tests: sucrose preference test (SPT), open field test (OFT), forced swim test (FST), and tail suspension test (TST) were conducted to assess depressive-like behaviors in the mice. Data analysis showed that there were significant intergroup differences in depressive-like behaviors in ICR and C57BL/6 J mice, while KM mice exhibited minor differences with relatively high deviation in individual behavioral score. This study indicated that the combined depression mouse model could successfully induce significant depressive-like behaviors in ICR and C57BL/6 J mice.

Research on Medical Image Segmentation Method Based on Improved U-Net3.

Computer assisted diagnostic technology has been widely used in clinical practice, specifically focusing on medical image segmentation. Its purpose is to segment targets with certain special meanings in medical images and extract relevant features, providing reliable basis for subsequent clinical diagnosis and research. However, because of different shapes and complex structures of segmentation targets in different medical images, some imaging techniques have similar characteristics, such as intensity, color, or texture, for imaging different organs and tissues. The localization and segmentation of targets in medical images remains an urgent technical challenge to be solved. As such, an improved full scale skip connection network structure for the CT liver image segmentation task is proposed. This structure includes a biomimetic attention module between the shallow encoder and the deep decoder, and the feature fusion proportion coefficient between the two is learned to enhance the attention of the overall network to the segmented target area. In addition, based on the traditional point sampling mechanism, an improved point sampling strategy is proposed for characterizing medical images to further enhance the edge segmentation effect of CT liver targets. The experimental results on the commonly used combined (CT-MR) health absolute organ segmentation (CHAOS) dataset show that the average dice similarity coefficient (DSC) can reach 0.9467, the average intersection over union (IOU) can reach 0.9623, and the average F1 score can reach 0.9351. This indicates that the model can effectively learn image detail features and global structural features, leading to improved segmentation of liver images.

Spectroscopic and Theoretical Identifications of Two Structural Motifs of (H2O)10 Cluster.

Precise characterization of archetypal systems of aqueous hydrogen-bonding networks is essential for developing accurate potential functions and universal models of water. The structures of water clusters (H2O)n (n = 2-9) have been verified recently through size-specific infrared spectroscopy with a vacuum ultraviolet free electron laser (VUV-FEL) and quantum chemical studies. For (H2O)10, the pentagonal prism and butterfly motifs were proposed to be important building blocks and were observed in previous experiments. Here we report the size-specific infrared spectra of (H2O)10 via a joint experimental and theoretical study. Well-resolved spectra provide a unique signature for the coexistence of pentagonal prism and butterfly motifs. These (H2O)10 motifs develop from the dominant structures of (H2O)n (n = 8, 9) clusters. This work provides an intriguing prelude to the diverse structure of liquid water and opens avenues for size-dependent measurement of larger systems to understand the stepwise formation mechanism of hydrogen-bonding networks.

Initiation time of double-filtration plasma apheresis affects the risk of persistent organ failure in hypertriglyceridaemia-induced acute pancreatitis: a retrospective study.

The effect of double filtration plasma apheresis (DFPP) on improving the outcomes of patients with hypertriglyceridaemia-induced acute pancreatitis (HTG-AP) remains unclear. The aim of this study was to evaluate the relationship between the initiation time of DFPP and the risk of persistent organ failure (POF) in an HTG-AP cohort in China. We retrospectively evaluated data from HTG-AP patients treated with DFPP 48 h after diagnosis between January 2017 and January 2022. Comparisons across tertiles of the interval from diagnosis to completion of one DFPP session (DTD) were analysed. Logistic regression models and restricted cubic splines (RCS) were used to determine the correlation between the DTD time and risk of POF. Of the 89 patients enrolled, 46 patients (51.69%) suffered POF in the first week of HTG-AP. DFPP was initiated at a median of 17 h after the diagnosis was confirmed. The patients in the highest tertile of DTD time had a significantly increased prevalence of POF. After multivariate adjustment, the logistic regression models found a significant decrease in the odds ratios (OR) of POF from the highest to the lowest DTD tertile (P for trend = 0.006). Moreover, the RCS curves showed a nonlinear relationship in the adjusted OR of POF and DTD time, which remained relatively low and flat during the early DTD time but increased sharply afterwards. Early initiation of DFPP treatment correlates with a reduced risk of POF in HTG-AP patients.

Capturing Hydrogen Radicals by Neutral Metal Hydroxides.

Capturing the hydrogen radical is of central importance in various systems ranging from catalysis to biology to astronomy, but it has been proven to be challenging experimentally because of its high reactivity and short lifetime. Here, neutral MO3H4 (M = Sc, Y, La) complexes were characterized by size-specific infrared-vacuum ultraviolet spectroscopy. All these products were determined to be the hydrogen radical adducts in the form of H•M(OH)3. The results indicate that the addition of the hydrogen radical to the M(OH)3 complex is both thermodynamically exothermic and kinetically facile in the gas phase. Moreover, the soft collisions in the cluster growth channel with the helium expansion were found to be demanded for the formation of H•M(OH)3. This work highlights the pivotal roles played by the soft collisions in the formation of hydrogen radical adducts and also opens new avenues toward the design and chemical control of compounds.

Size-Specific Infrared Spectroscopic Study of the Reactions between Water Molecules and Neutral Vanadium Dimer: Evidence for Water Splitting.

Investigation of the reactions between water molecules and neutral metal clusters is important in water splitting but is very challenging due to the inherent difficulty of size selection. Here, we report a size-specific infrared-vacuum ultraviolet spectroscopic study on the reactions of water with neutral vanadium dimer. The V2O3H4 and V2O4H6 products were characterized to have unexpected V2(µ2-OH)(µ2-H)(η1-OH)2 and V2(µ2-OH)2(η1-H)2(η1-OH)2 structures, indicative of a water decomposition. A combination of theory and experiment reveals that the water splitting by V2 is both thermodynamically exothermic and kinetically facile in the gas phase. The present system serves as a model for clarifying the pivotal roles played by neutral metal clusters in water decomposition and also opens new avenues toward systematic understanding of water splitting by a large variety of single-cluster catalysts.

Topology Hierarchy of Transition Metal Dichalcogenides Built from Quantum Spin Hall Layers.

The evolution of the physical properties of 2D material from monolayer limit to the bulk reveals unique consequences from dimension confinement and provides a distinct tuning knob for applications. Monolayer 1T'-phase transition metal dichalcogenides (1T'-TMDs) with ubiquitous quantum spin Hall (QSH) states are ideal 2D building blocks of various 3D topological phases. However, the stacking geometry has been previously limited to the bulk 1T'-WTe2 type. Here, the novel 2M-TMDs consisting of translationally stacked 1T'-monolayers are introduced as promising material platforms with tunable inverted bandgaps and interlayer coupling. By performing advanced polarization-dependent angle-resolved photoemission spectroscopy as well as first-principles calculations on the electronic structure of 2M-TMDs, a topology hierarchy is revealed: 2M-WSe2 , MoS2, and MoSe2 are weak topological insulators (WTIs), whereas 2M-WS2 is a strong topological insulator (STI). Further demonstration of topological phase transitions by tunning interlayer distance indicates that band inversion amplitude and interlayer coupling jointly determine different topological states in 2M-TMDs. It is proposed that 2M-TMDs are parent compounds of various exotic phases including topological superconductors and promise great application potentials in quantum electronics due to their flexibility in patterning with 2D materials.

A Mesoscale Study on the Dilation of Actively Confined Concrete under Axial Compression.

The confinement of concrete enhances its strength and ductility by restraining lateral dilation. The accuracy of a confinement model depends on how well it captures the dilation of concrete. In the current paper, a mesoscale model is established to study the dilation properties of concrete in active confinement, where the heterogeneity of concrete is considered. The stress-strain and lateral-axial strain curves of concrete in active confinement were used to demonstrate the validity of the mesoscale model. Subsequently, the distribution of lateral strain and the influences of the strength grade and confinement ratio on the dilation of concrete were investigated in a simulation. The results show that the distribution of the lateral strain along the radial or longitudinal directions is not uniform on the specimen when compressive failure occurs. The confinement ratio has a more significant influence on the concrete's transverse dilation than the strength grade. Finally, an expression of the lateral-axial strain relationship of concrete in active confinement is proposed. The proposed formula can reflect the simulation results of the mesoscale model and is in good agreement with the prediction of existing formulas.