Douchi is a highly appreciated product due to its unique flavor, high nutritional value, and health benefits. Douchi from different regions exhibits distinct characteristics. The objective of this study was to investigate the volatile profiles in douchi produced from different geographical origins using gas chromatography-mass spectrometry (GC-MS) and chemometrics. The volatiles were extracted by headspace solid-phase micro-extraction (HS-SPME) and subsequently determined by GC-MS. A comparative analysis was further conducted to identify the variations in volatile compounds among the samples. The correlation between the samples was investigated by employing cluster analysis (CA) and principal component analysis (PCA). An orthogonal partial least squares-discriminant analysis (OPLS-DA) model was established to discriminate samples from different regions and identify key differential compounds. A total of 46 volatile compounds were detected, among which terpenes, alcohols were the main compounds. Furthermore, 14 key differentiating compounds were screened out based on the OPLS-DA modle. The application of GC-MS combined with chemometrics offers a theoretical framework for douchi quality control and classification.

AIM: to improve the algorithm and results of surgical treatment of combat wounds of the rectum. PATIENTS AND METHODS: thirty-one patients with combat injuries of the rectum were included in the cohort. RESULTS: twenty-seven (87.1 %) patients were discharged in satisfactory condition, 4 (12,9 %) patients died. Sepsis developed in all four patients: in two of them sepsis was on the background of necrotising fasciitis and one had peritonitis. Endoscopic control revealed 10 wounds of the extraperitoneal part of the rectum undiagnosed at the 1st and 2nd stages of medical care. Surgical care included all four main components: diverting stoma, distal washout (mechanical cleansing of the rectum to clear water), suturing of the lesion through perineal access, drainage or tamponisation of the presacral space was done in 20 (64.5 %) patients. Endoluminal VAC therapy was used in 12 patients. In 11 of them, VAC treatment was successful with complete healing of rectal wall wounds. CONCLUSION: the four-component treatment approach is the optimal option for wounds of the extraperitoneal part of the rectum. Diverting stoma and distal bowel washout prevents severe infection. Endoluminal VAC therapy, in some cases, can be used as an alternative to presacral drainage and suturing of the rectal wall lesion.

The recent discovery of high-temperature superfluorescence in hybrid perovskite thin films has opened new possibilities for harnessing macroscopic quantum phenomena in nanotechnology. This study aimed to elucidate the mechanism that enables high-temperature superfluorescence in these systems. The proposed model describes a quasi-2D Wannier exciton in a thin film that interacts with phonons via the longitudinal optical phonon-exciton Fröhlich interaction. We show that the super-radiant properties of the coherent state in hybrid perovskites are stable against perturbations caused by the longitudinal optical phonon-exciton Fröhlich interaction. Using the multiconfiguration Hartree approach, we derive semiclassical equations of motion for a single-exciton wavefunction, where the vibrational degrees of freedom interact with the Wannier exciton through a mean-field Hartree term. Super-radiance is effectively described by a non-Hermitian term in the Hamiltonian. The analysis was then extended to multiple excited states using the semiclassical Hamiltonian as the basic model. We demonstrate that the ground state of the model exciton Hamiltonian with long-range interactions is a symmetric Dicke super-radiant state, where the Fröhlich interaction is nullified. The additional density matrix-based consideration draws an analogy between this system and stable systems, where the conservation laws determine the nullification of the constant (momentum-independent) decay rate part. In the exciton-phonon system, nullification is associated with the absence of a momentum-independent component in the Wannier exciton-phonon interaction coupling function.

Path-like collective variables (CVs) can be very effective for accurately modeling complex biomolecular processes in molecular dynamics simulations. Recently, we have introduced DeepLNE (deep-locally non-linear-embedding), a machine learning-based path-like CV that provides a progression variable s along the path as a non-linear combination of several descriptors. We have demonstrated the effectiveness of DeepLNE by showing that for simple models such as the Müller-Brown potential and alanine dipeptide, the progression along the path variable closely approximates the ideal reaction coordinate. However, DeepLNE is computationally expensive for realistic systems needing many descriptors and limited in its ability to handle multi-state reactions. Here, we present DeepLNE++, which uses a knowledge distillation approach to significantly accelerate the evaluation of DeepLNE, making it feasible to compute free energy landscapes for large and complex biomolecular systems. In addition, DeepLNE++ encodes system-specific knowledge within a supervised multitasking framework, enhancing its versatility and effectiveness.

A novel statistical mechanical methodology is applied to clusters of N ≤ 7 atoms. Exact statistical analogs for any energy derivative of entropy ∂mS/∂Em are used in rigorous microcanonical Monte Carlo simulations to vastly enlarge the pool of measurable thermodynamic properties relative to previous work. All analogs are given for two alternative partition functions of the microcanonical ensemble. Coarse grained energy distributions are used to establish the existence of melting transitions. LJ7, LJ5, and LJ4 are found to exhibit trimodal distributions, a feature not being reported before. Varieties of combinations of entropy derivatives are tested for a direct detection of the melting region. It is shown that for such a purpose, derivatives of at least fourth order are necessary.

By simulation and asymptotic theory, we investigate the transition-path time of a one-dimensional finite-mass reaction coordinate crossing a double-well potential in the presence of non-Markovian friction. First, we consider single-exponential memory kernels and demonstrate that memory accelerates transition paths compared to the Markovian case, especially in the low-mass/high-friction limit. Then, we generalize to multi-exponential kernels and construct an asymptotic formula for the transition-path time that compares well with simulation data.

Monte Carlo simulations are widely employed to measure the physical properties of glass-forming liquids in thermal equilibrium. Combined with local Monte Carlo moves, the Metropolis algorithm can also be used to simulate the relaxation dynamics, thus offering an efficient alternative to molecular dynamics. Monte Carlo simulations are, however, more versatile because carefully designed Monte Carlo algorithms can more efficiently sample the rugged free energy landscape characteristic of glassy systems. After a brief overview of Monte Carlo studies of glass-formers, we define and implement a series of Monte Carlo algorithms in a three-dimensional model of polydisperse hard spheres. We show that the standard local Metropolis algorithm is the slowest and that implementing collective moves or breaking detailed balance enhances the efficiency of the Monte Carlo sampling. We use time correlation functions to provide a microscopic interpretation of these observations. Seventy years after its invention, the Monte Carlo method remains the most efficient and versatile tool to compute low-temperature properties in supercooled liquids.

In this study, we have conducted a comparative analysis of the structural ordering of short oligoetherimide chains (dimers) near the bounding surface, depending on the structure of that surface. In order to clarify the possibility of oligoetherimide ordering along the symmetry axes of graphene, two types of bounding surfaces were considered: graphene, with a regular discrete position of interaction centers (carbon atoms), and a smooth, structureless impermeable wall. The chemical structures of the considered dimers consist of two repeating units of BPDA-P3, ODPA-P3, or aBPDA-P3 thermoplastic polyetherimides. Using all-atom molecular dynamics simulations, the process of structural ordering of the dimers near the surface of the graphene or wall was established. The ODPA-P3 and BPDA-P3 dimers form an ordered state near the graphene surface, while the aBPDA-P3 dimers do not demonstrate structural ordering. The simulation results confirmed that the ordering direction of the BPDA-P3 and ODPA-P3 dimers near the graphene surface is chosen randomly. Comparison of the oligoetherimide structure formed near the attracting wall without a symmetrical location of the interaction centers shows the similarity of the ordering of dimers near the graphene surface and the wall. As in the case of the graphene surface, the ordering of oligoetherimide molecules near the structureless wall demonstrates one direction of ordering. Therefore, we confirmed that the key factor for the onset of ordering is the presence of a confining surface, rather than the symmetrical arrangement of interaction centers in the substrate structure.