Unveiling the Role of Water on π-π Stacking Through Microwave Spectroscopy of (Thiophene)2-(Water)1-2 Clusters.

There has been an ongoing debate about whether water enhances or hinders π-π stacking, a phenomenon crucial in various biological and chemical systems. In this study, the influence of water on π-π stacking is investigated by microwave spectroscopic observation of gas-phase hydrated clusters of thiophene dimers. Two isomers of (C4H4S)2-H2O and two isomers of (C4H4S)2-(H2O)2 have been unambiguously identified. These identifications are supported by quantum chemistry calculations and isotopic measurements. In each of these conformations, water molecules are situated between aromatic pairs, forming distinctive interactions. Water molecules engage with thiophene molecules either as hydrogen bond donors through OH···π interactions or as hydrogen bond acceptors through CH···O interactions. The energy decomposition analysis indicates that the bonding pattern of water molecules significantly affects the π···π interactions between aromatic rings. These findings offer valuable structural insights into the role of water in shaping π-π stacking.

Spectroscopic Study of [Mg, H, N, C, O] Species: Implications for the Astrochemical Magnesium Chemistry.

Magnesium is an abundant metal element in space, and magnesium chemistry has vital importance in the evolution of interstellar medium (ISM) and circumstellar regions, such as the asymptotic giant branch star IRC+10216 where a variety of Mg compounds bearing H, C, N, and O have been detected and proposed as the important components in the gas-phase molecular clouds and solid-state dust grains. Herein, we report the formation and infrared spectroscopic characterization of the Mg-bearing molecules HMg, [Mg, N, C], [Mg, H, N, C], [Mg, N, C, O], and [Mg, H, N, C, O] from the reactions of Mg/Mg+ and the prebiotic isocyanic acid (HNCO) in the solid neon matrix. Based on their thermal diffusion and photochemical behavior, a complex reactivity landscape involving association, decomposition, and isomerization reactions of these Mg-bearing molecules is developed, which can not only help understand the chemical processes of the magnesium (iso)cyanides in astrochemistry but also provide implications on the presence of magnesium (iso)cyanates in the ISM and the chemical model for the dust grain surface reactions. It also provides a new paradigm of the key intermediate nature of the cationic complexes in the formation of neutral interstellar species.

A rotational spectroscopy study of microsolvation effects on intramolecular proton transfer in trifluoroacetylacetone-(H2O)1-3.

Trifluoroacetylacetone (TFAA) has two enol forms, which can switch to each other via proton transfer. While much attention has been paid to their conformational preferences, the influence of microsolvation on regulating the proton position remains unexplored. Herein, we report the rotational spectra of trifluoroacetylacetone-(water)n (n = 1-3) investigated by chirped pulse Fourier transform microwave spectroscopy in the 2-8 GHz frequency range. Two conformers were identified for both TFAA-H2O and TFAA-(H2O)2, while only one conformer was characterized for TFAA-(H2O)3. The results indicate that water binding on the CH3 side stabilizes the enolF form, whereas water binding on the CF3 side stabilizes the enolH form. The enolF form predominates over the enolH form in these hydrated complexes, which contrasts with the fact that only enolH exists in isolated TFAA. EnolH becomes preferred only when water inserts itself into the intramolecular hydrogen bond. Instanton theory calculations reveal that the proton transfer reaction is dominated by quantum tunneling at low temperatures, leading to the stable existence of only one enol form in each configuration of the hydrated clusters.

Infrared Spectroscopy of [M(CO2)n]+ (M = Ca, Sr, and Ba; n = 1-4) in the Gas Phase: Solvation-Induced Electron Transfer and Activation of CO2.

Cationic complexes of heavy alkaline earth metal and carbon dioxide [M(CO2)n]+ (M = Ca, Sr, and Ba) are produced by a laser vaporization-supersonic expansion ion source in the gas phase and are studied by infrared photodissociation spectroscopy in conjunction with quantum chemistry calculations. For the n = 1 complexes, the metal-ligand binding arises primarily from the electrostatic interaction with the CO2 ligand bound to the metal (+I) center in an end-on η1-O fashion. The more highly coordinated complexes [M(CO2)n]+ with n ≥ 2 are characterized to involve a [M2+(CO2-)] core ion with the CO2- ligand bound to the metal (+II) center in a bidentate η2-O, O manner. The activation of CO2 in forming a bent CO2- moiety occurs via solvation-induced metal cation-ligand electron transfer reactions. Bonding analyses reveal that the attractive forces between M2+ and CO2- in the core cation come mainly from electrostatic attraction, but the contribution of covalent orbital interactions should not be underestimated. The atomic orbitals of metal dications that are engaged in the orbital interactions are ns and (n - 1)d orbitals.

Intestinal Microbiota Modulates the Antitumor Effect of Oncolytic Virus Vaccines in Colorectal Cancer.

BACKGROUND: Immunotherapies, such as oncolytic viruses, have become powerful cancer treatments, but only some patients with cancer can benefit from them, especially those with advanced-stage cancer, and new therapeutic strategies are needed to facilitate extended survival. The intestinal microbiota may contribute to colorectal cancer (CRC) carcinogenesis and the response to immunotherapy. However, whether and how the intestinal microbiota modulates the effects of oncolytic virus vaccines (OVVs) in CRC remain to be investigated. METHODS: We generated an MC38-gp33 CRC mouse model and treated it with OVV-gp33 in early and advanced stages. Probiotics, fecal microbiota transplantation (FMT), and antibiotics (ABX) were administered to regulate the microbial composition of CRC mice at an advanced stage. The tumor growth rate and survival time of the mice were recorded; 16S rDNA sequencing was used to analyze the microbial composition and flow cytometry was used to detect T-cell subset activity. RESULTS: OVV-gp33 treatment inhibited tumor growth and prolonged survival in the early stage of CRC but did not have a significant effect on the advanced stage of CRC. Moreover, 16S rDNA sequence analysis and flow cytometry showed significant differences in intestinal microbiota composition, microbial metabolites, and T-cell subsets in early and advanced-stage CRC. Probiotic and FMT treatment significantly enhanced the antitumor effect of OVV in the advanced stage of CRC with an increased abundance of activated CD8+ T cells and a decreased ratio of Treg cells, while depletion of the microbiota by ABX eliminated the antitumor activity of OVV with decreased CD8+ T-cell activation and upregulated Treg cells. CONCLUSIONS: These results indicate that the intestinal microbiota and microbial metabolites play an important role in the antitumor effect of OVV in CRC. Furthermore, altering the intestinal microbiota composition can modulate the antitumor and immunomodulatory effects of OVV in CRC.

PDMS diaphragm based miniature fiber-optic Fabry-Perot dynamic pressure sensor for turbomachinery application.

Small-sized, highly sensitive dynamic pressure sensors are crucial in the field of turbomachinery application. In this paper, a fiber-tip structure dynamic pressure sensor utilizing a small piece of glass tube as the air cavity and PDMS material as the diaphragm was fabricated. It has the advantage of being small in size with the diameter of 125 µm while having high sensitivity of 26.26 pm/kPa. The fabrication process was described in detail, which is simple and cost-effective. The sensor characteristics were studied theoretically and experimentally. Quasi-square pressure signal of different frequencies generated by the siren disk were measured by the sensor and compared with that obtained from the commercial piezoresistive pressure sensor to verify the accuracy of the proposed sensor. The R2 of the four pairs of pressure waveforms were 0.94, 0.81, 0.93, and 0.96, respectively. Stability testing of the sensor was also performed, showing that the sensor can work reliably under dynamic pressure environment.

Evolution of Solute-Water Interactions in the Benzaldehyde-(H2O)1-6 Clusters by Rotational Spectroscopy.

The investigation on the preferred arrangement and intermolecular interactions of gas phase solute-water clusters gives insights into the intermolecular potentials that govern the structure and dynamics of the aqueous solutions. Here, we report the investigation of hydrated coordination networks of benzaldehyde-(water)n (n = 1-6) clusters in a pulsed supersonic expansion using broadband rotational spectroscopy. Benzaldehyde (PhCHO) is the simplest aromatic aldehyde that involves both hydrophilic (CHO) and hydrophobic (phenyl ring) functional groups, which can mimic molecules of biological significance. For the n = 1-3 clusters, the water molecules are connected around the hydrophilic CHO moiety of benzaldehyde through a strong CO···HO hydrogen bond and weak CH···OH hydrogen bond(s). For the larger clusters, the spectra are consistent with the structures in which the water clusters are coordinated on the surface of PhCHO with both the hydrophilic CHO and hydrophobic phenyl ring groups being involved in the bonding interactions. The presence of benzaldehyde does not strongly interfere with the cyclic water tetramer and pentamer, which retain the same structure as in the pure water cluster. The book isomer instead of cage or prism isomers of the water hexamer is incorporated into the microsolvated cluster. The PhCHO molecule deviates from the planar structure upon sequential addition of water molecules. The PhCHO-(H2O)1-6 clusters may serve as a simple model system in understanding the solute-water interactions of biologically relevant molecules in an aqueous environment.

Formation and infrared spectroscopic characterization of carbon suboxide complexes TM-η1 -C3 O2 and the inserted ketenylidene complexes OCTMCCO (TM=Cu, Ag, Au) in solid neon.

The reactions of coinage metal atoms Cu, Ag and Au with carbon suboxide (C3 O2 ) are studied by matrix isolation infrared spectroscopy. The weakly bound complexes TM-η1 -C3 O2 (TM=Cu, Ag, Au), in which the carbon suboxide ligand binds to the metal center in the monohapto fashion are formed as initial reaction products. The complexes subsequently isomerize to the inserted products OCTMCCO upon visible light (λ = 400-500 nm) excitation. The analysis of the electronic structure using modern quantum chemistry methods suggests that the linear OCTMCCO complexes are best described by the bonding interactions between the TM+ cation in the electronic singlet ground state and the [OC…CCO]- ligands in the doublet state forming two TM+ ← ligands σ donation and two TM+ → ligands π backdonation bonding components. In addition, the CuCCO, AgCCO and AuCCO complexes are also formed, which are predicted to be bent.

High-efficiency FBG array sensor interrogation system via a neural network working with sparse data.

FBG array sensors have been widely used in the multi-point monitoring of large structures due to their excellent optical multiplexing capability. This paper proposes a cost-effective demodulation system for FBG array sensors based on a Neural Network (NN). The stress variations applied to the FBG array sensor are encoded by the array waveguide grating (AWG) as transmitted intensities under different channels and fed to an end-to-end NN model, which receives them and simultaneously establishes a complex nonlinear relationship between the transmitted intensity and the actual wavelength to achieve absolute interrogation of the peak wavelength. In addition, a low-cost data augmentation strategy is introduced to break the data size bottleneck common in data-driven methods so that the NN can still achieve superior performance with small-scale data. In summary, the demodulation system provides an efficient and reliable solution for multi-point monitoring of large structures based on FBG array sensors.

Phosphorus-Boron Multiple Bonding in the π Radical HBP.

The HBP radical was generated via the reaction of laser ablated boron atom with PH3 in a solid neon matrix, which is identified via IR spectroscopy with isotopic substitutions and quantum chemical calculations. The results show that HBP has a 2 Π electronic ground state with a short B-P bond. Bonding analysis indicates that besides an electron-sharing σ bond, there are two degenerate π bonding orbitals that are occupied by three electrons, resulting in a bond order of two and half between P and B. This is in sharp contrast to the bonding properties of the isovalent HNB, which was characterized to be a N≡B triply bonded σ radical with the unpaired electron locating on the B atom.

Efficacy of an internet-based cognitive behavioral therapy for subthreshold depression among Chinese adults: a randomized controlled trial.

BACKGROUND: Subthreshold depression (sD) negatively impacts well-being and psychosocial function and is more prevalent compared with major depressive disorder (MDD). However, as adults with sD are less likely to seek face-to-face intervention, internet-based cognitive-behavioral therapy (ICBT) may overcome barriers of accessibility to psychotherapy. Although several trials explored the efficacy of ICBT for sD, the results remain inconsistent. This study evaluated whether ICBT is effective in reducing depressive symptoms among Chinese adults with sD. METHODS: A randomized controlled trial was performed. The participants were randomly assigned to 5 weeks of ICBT, group-based face-to-face cognitive-behavioral therapy (CBT), or a waiting list (WL). Assessments were conducted at baseline, post-intervention and at a 6-month follow-up. The primary outcome measured depressive symptoms using the Center for Epidemiological Studies Depression Scale (CES-D). Outcomes were analyzed using a mixed-effects model to assess the effects of ICBT. RESULTS: ICBT participants reported greater reductions on all the outcomes compared to the WL group at post-intervention. The ICBT group showed larger improvement on the Patient Health Questionnaire-9 (PHQ-9) at post-intervention (d = 0.12) and at follow-up (d = 0.10), and with CES-D at post-intervention (d = 0.06), compared to the CBT group. CONCLUSIONS: ICBT is effective in reducing depressive symptoms among Chinese adults with sD, and improvements in outcomes were sustained at a 6-month follow-up. Considering the low rates of face-to-face psychotherapy, our findings highlight the considerable potential and implications for the Chinese government to promote the use of ICBT for sD in China.

TRPV1 is a risk factor for sleep disturbance in patients with gastro-oesophageal reflux disease: a case control study.

BACKGROUND/AIMS: Gastro-oesophageal reflux disease (GORD) is a chronic high-morbidity disease with a bidirectional relationship with sleep disturbance (SD) that may occur via the transient receptor potential vanilloid type 1 receptor (TRPV1) in the oesophageal mucosa. Yet the related mechanism was still unclear, the aim of this study is to investigate whether TRPV1 is associated with the presence of SD in GORD patients. METHODS: A case-control study was performed. After the screening, A total of 88 subjects were assigned to GORD without sleep disturbance (GORD + NOSD, n = 28), GORD comorbid sleep disturbance (GORD + SD, n = 30) and matched healthy controls (n = 30). Mucosal tissue was obtained from the participants by digestive endoscopy, the levels of TRPV1 expressed in the oesophageal mucosa were detected via RT-qPCR and western blot in different groups, and the correlation between GORD and SD were also analysed. RESULTS: In this study, we found that the Gastroesophageal Reflux Disease Diagnostic Questionnaire (GerdQ) scores was positively correlated with Pittsburgh Sleep Quality Index (PSQI) scores but negatively correlated with total sleep time (TST). We also found that the level of TRPV1 expressed in the oesophageal mucosa of GORD + SD was significantly higher than GORD + NOSD patients, and they were all higher than healthy controls. CONCLUSION: The current study suggested a closer link exists between GORD and sleep disturbance, and TRPV1 in oesophageal mucosa may be a crucial factor affecting sleep in GORD patients.

Alterations in Resting-State Interhemispheric Coordination With Refractory Auditory Verbal Hallucinations in Schizophrenia.

OBJECTIVE: The purpose of this study was to investigate resting-state interhemispheric functional connectivity in patients with schizophrenia and refractory auditory verbal hallucinations (RAVHs) by using voxel-mirrored homotopic connectivity (VMHC). METHODS: Thirty-four patients with schizophrenia and RAVHs (RAVH group), 23 patients with schizophrenia but no auditory verbal hallucinations (non-AVH group), and 28 matched healthy volunteers (healthy control group) were recruited in China. VMHC analyses were used to identify brain areas with significant differences in functional connectivity among the three groups, and correlations between symptom scores and neurological measures were examined. RESULTS: VMHC analyses showed aberrant bilateral connectivity between several homotopic brain regions: the RAVH and non-AVH groups showed differences in bilateral connectivity of the superior and middle temporal gyri, and the RAVH and healthy control groups showed differences in bilateral connectivity of the gyrus rectus, inferior frontal gyrus, and putamen. In addition, interhemispheric connectivity of the superior and middle temporal gyri correlated with patients' positive symptom scores. CONCLUSIONS: These findings may help to elucidate the pathophysiological mechanisms underlying auditory verbal hallucinations. The results revealed interhemispheric functional dysconnectivity among patients with schizophrenia and suggest that the dysconnectivity of homotopic brain regions may play an important role in the development of auditory verbal hallucinations.

Mg(I)-Fe(-II) and Mg(0)-Mg(I) covalent bonding in the MgnFe(CO)4- (n = 1, 2) anion complexes: an infrared photodissociation spectroscopic and theoretical study.

Heteronuclear magnesium-iron carbonyl anion complexes MgFe(CO)4- and Mg2Fe(CO)4- are produced in the gas phase and are detected by mass-selected infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The geometric structures and the metal-metal bonding are discussed with the aid of quantum chemical calculations. Both complexes are characterized to have a doublet electronic ground state with C3v symmetry containing a Mg-Fe bond or a Mg-Mg-Fe bonding unit. Bonding analyses indicate that each complex involves an electron-sharing Mg(I)-Fe(-II) σ bond. The Mg2Fe(CO)4- complex involves a relatively weak covalent Mg(0)-Mg(I) σ bond.

Infrared photodissociation spectroscopy of mass-selected [TaO3(CO2)n]+ (n = 2-5) complexes in the gas phase.

We report a joint experimental and theoretical study on the structures of gas-phase [TaO3(CO2)n]+ (n = 2-5) ion-molecule complexes. Infrared photodissociation spectra of mass-selected [TaO3(CO2)n]+ complexes were recorded in the frequency region from 2200 to 2450 cm-1 and assigned through comparing with the simulated infrared spectra of energetically low-lying structures derived from quantum chemical calculations. With the increasing number of attached CO2 molecules, the larger clusters show significantly enhanced fragmentation efficiency and a strong band appears at around 2350 cm-1 near the free CO2 antisymmetric stretching vibration band, indicating only a small perturbation of CO2 molecules on the secondary solvation sphere while higher frequency bands corresponding to the core structure remain largely unaffected. A core structure [TaO3(CO2)3]+ is identified to which subsequent CO2 ligands are weakly attached and the most favorable cluster growth path is verified to proceed on the triplet potential energy surface higher in energy than that of ground states. Theoretical exploration reveals a two-state reactivity (TSR) scenario in which the energetically favored triplet transition state crosses over the singlet ground state to form a TaO3+ core ion, providing new information on the cluster formation correlated with the reactivity of tantalum metal oxides towards CO2.

Mg-Fe Bonding in the MgFe(CO)n+ (n = 4-9) Cation Complexes: An Infrared Photodissociation Spectroscopic and Theoretical Study.

Heteronuclear magnesium-iron carbonyl cation complexes MgFe(CO)n+ (n = 4-9) are prepared in the gas phase and are detected by mass-selected infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The geometric structures and the metal-metal bonding are discussed with the aid of quantum chemical calculations. The MgFe(CO)9+ cation is a coordinatively saturated complex. Each complex is characterized to contain more than one isomer. The small complexes (n = 4-6) possess the Mg-Fe bonded [(OC)n-4Mg-Fe(CO)4]+ and/or [(OC)n-5Mg-Fe(CO)5]+ structures with all the carbonyl ligands terminally bonded. For the larger complexes with n = 7-9, the [(OC)n-4Mg-Fe(CO)4]+ structure is the major isomer experimentally observed. In addition, the [(OC)n-5Mg-OC-Fe(CO)4]+ isomer involving a linear bridging carbonyl ligand is also characterized. Bonding analyses indicate that each [(OC)n-4Mg-Fe(CO)4]+ complex contains a Mg-Fe electron-sharing σ bond. The metal-metal bond is described as a Mg(+I)-Fe(0) bond in MgFe(CO)4+ and as a Mg(+II)-Fe(-I) bond in the larger n = 5-9 complexes.

Displacement Monitoring of a Bridge Based on BDS Measurement by CEEMDAN-Adaptive Threshold Wavelet Method.

From the viewpoint of BDS bridge displacement monitoring, which is easily affected by background noise and the calculation of a fixed threshold value in the wavelet filtering algorithm, which is often related to the data length. In this paper, a data processing method of Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), combined with adaptive threshold wavelet de-noising is proposed. The adaptive threshold wavelet filtering method composed of the mean and variance of wavelet coefficients of each layer is used to de-noise the BDS displacement monitoring data. CEEMDAN was used to decompose the displacement response data of the bridge to obtain the intrinsic mode function (IMF). Correlation coefficients were used to distinguish the noisy component from the effective component, and the adaptive threshold wavelet de-noising occurred on the noisy component. Finally, all IMF were restructured. The simulation experiment and the BDS displacement monitoring data of Nanmao Bridge were verified. The results demonstrated that the proposed method could effectively suppress random noise and multipath noise, and effectively obtain the real response of bridge displacement.

Synthesis of Axially Chiral QUINAP Derivatives by Ketone-Catalyzed Enantioselective Oxidation.

QUINAPs have emerged as a pivotal class of axially chiral compounds with remarkable features in the stereoinduction of diverse enantioselective transformations. However, the confined substrate range and extravagant price still pose challenges, limiting their broader utilization. Herein, we describe the first atroposelective oxidation of an N atom using a chiral ketone catalyst, allowing the kinetic resolution of QUINAPOs to give both the unreacted substrates and their corresponding N-oxides with excellent enantioselectivity. Importantly, the enantioenriched products can be readily converted into the QUINAP targets without any loss of stereochemical integrity. Mechanistic investigations indicate that a dioxirane, generated through the oxidation of the ketone with oxone, acts as the active catalytic species. Furthermore, we have successfully extended this catalytic system to the kinetic resolution of QUINOLs and the dynamic kinetic transformation of pyridine analogues of QUINAPO possessing a labile stereogenic axis. The practicality of the developed protocol is further demonstrated by the successful application of QUINAPO N-oxide as a Lewis base catalyst in a series of enantioselective transformations.

Cost-effective improvement of the performance of AWG-based FBG wavelength interrogation via a cascaded neural network.

Fiber Bragg grating (FBG) sensors have been widely applied in various applications, especially for structural health monitoring. Low cost, wide range, and low error are necessary for an excellent performance FBG sensor signal demodulation system. Yet the improvement of performance is commonly accompanied by costly and complex systems. A high-performance, low-cost wavelength interrogation method for FBG sensors was introduced in this paper. The information from the FBG sensor signal was extracted by the array waveguide grating (AWG) and fed into the proposed cascaded neural network. The proposed network was constructed by cascading a convolutional neural network and a residual backpropagation neural network. We demonstrate that our network yields a vastly significant performance improvement in AWG-based wavelength interrogation over that given by other machine learning models and validate it in experiments. The proposed network cost-effectively widens the wavelength interrogation range of the demodulation system and optimizes the wavelength interrogation error substantially, also making the system scalable.

Fabry-Perot interferometric sensor demodulation system utilizing multi-peak wavelength tracking and neural network algorithm.

For FPI sensor demodulation systems to be used in actual engineering measurement, they must have high performance, low cost, stability, and scalability. Excellent performance, however, necessitates expensive equipment and advanced algorithms. This research provides a new absolute demodulation system for FPI sensors that is high-performance and cost-effective. The reflected light from the sensor was demultiplexed into distinct channels using an array waveguide grating (AWG), with the interference spectrum features change translated as the variation of the transmitted intensity in each AWG channel. This data was fed into an end-to-end neural network model, which was utilized to interrogate multiple interference peaks' absolute peak wavelengths simultaneously. This architecturally simple network model can achieve remarkable generalization capabilities without training large-scale datasets using an appropriate data augmentation strategy. Experiments show that in simultaneous multi-wavelength and cavity length interrogations, the proposed system has the precision of up to ± 14 pm and ± 0.07 µm, respectively. The interrogation resolution can theoretically reach the pm level benefit from the neural network method. Furthermore, the system's outstanding demodulation repeatability and suitability were demonstrated. The system is expected to provide a high-performance and cost-effective, reliable solution for practical engineering applications.