Open Configuration Research Articles

The mechanical environment regulates the extent of aortic valve calcification and thickness: an ex vivo whole mouse heart study

Abstract Background Aortic stenosis (AS) is a narrowing of the aortic valve opening due to calcification and thickening of the leaflets. Calcifications are mostly located at regions with high mechanical stress and disturbed flow suggesting that mechanical environment is important in the regulation of calcification. However, direct evidence linking valve calcification and mechanical stress is still lacking. Recently, we established an ex vivo calcification model for whole mouse hearts (Miniature Tissue Culture System MTCS) which allows the study of the mechanical environment underlying aortic valve calcification. Purpose Aim of this study was to investigate the role of mechanical stress on aortic valve calcification and thickening using the MTCS. Methods Whole mouse hearts were cultured in the MTCS with 2 distinct configurations: 1) medium flowing from the aorta towards the aortic valve to create a continuous closed aortic valve (n=28) and 2) medium flowing from the left ventricle through the aortic valve towards the aorta to create a continuous open aortic valve (n=17) (Figure1). The hearts were subjected to low (300 ul/min) or high (3000 ul/min) flow speed in the presence of calcifying medium (3mM phosphate buffer). After culture for 1 week, the hearts were isolated and fixed overnight with 4% PFA/PBS. Alizarin red staining was performed to determine calcification presence. Quantifications were performed using Caseviewer software. Results Aortic valves in closed configuration exposed to a high flow speed, exhibited significant increase in calcification compared to aortic valves in the closed configuration exposed to low flow speed or aortic valve cultured in the open position (p<0.01, Figure2A). Of interest, the extent of calcification in the aortic valve in closed position exposed to high flow speed strongly correlated with the diameter of the aortic annulus (R²=0.86, p<0.0001, Figure2B). Conversely, leaflet thickness was significantly lower in the closed aortic valve configuration as compared with the open aortic valves configuration (p<0.05, p<0.001, Figure2C). Conclusion Our study demonstrates the influence of mechanical environment on aortic valve calcification and thickening. The presence of calcification in the closed but not the open aortic valve configuration exposed to high flow suggests that increased pressure promotes calcification. The correlation of the extent of aortic valve calcification with the diameter of the aortic annulus implies that configuration of the valve is an important determinator of calcification, with potential implications for the results of aortic valve repair. The presence of a minimal amount of mechanical stress as experienced by aortic valves in the open position, however, resulted in thicker aortic valves, indicating that the right balance of mechanical stresses is required to maintain normal valve morphology. These findings provide valuable insights into AS pathogenesis, guiding future therapeutic approaches.ex vivo cultured aortic valvesCalcification in ex vivo aortic valves

Using simulated human comfort matrix to measure urban campus gender-based thermal performances

The study proposes incorporating human bodily comfort performance through a simulation method to assess the impact of urban microclimate conditions in an urban campus area. A human comfort performance matrix is used based on PET value and gender’s thermal stress conditions. The investigation serves as a way to evaluate open spaces’ climatic performance quantitatively through energy simulation. The method shows a way to measure urban comfort regarding gender perspectives early in the urban decision-making process. The findings of this research have practical implications for urban decision-makers to use robust simulation tools to optimize open space configurations based on gender’s thermal performances.

Rational Design of High-Performance Photocontrolled Molecular Switches Based on Chiroptical Dimethylcethrene: A Theoretical Study.

The reversible photo-induced conformation transition of a single molecule with a [5]helicene backbone has garnered considerable interest in recent studies. Based on such a switching process, one can build molecular photo-driven switches for potential applications of nanoelectronics. But the achievement of high-performance reversible single-molecule photoswitches is still rare. Here, we theoretically propose a 13,14-dimethylcethrene switch whose photoisomerization between the ring-closed and ring-open forms can be triggered by ultraviolet (UV) and visible light irradiation. The electronic structure transitions and charge transport characteristics, concurrent with the photo-driven electrocyclization of the molecule, are calculated by the non-equilibrium Green's function (NEGF) in combination with density functional theory (DFT). The electrical conductivity bears great diversity between the closed and open configurations, certifying the switching behavior and leading to a maximum on-off ratio of up to 103, which is considerable in organic junctions. Further analysis confirms the evident switching behaviors affected by the molecule-electrode interfaces in molecular junctions. Our findings are helpful for the rational design of organic photoswitches at the single-molecule level based on cethrene and analogous organic molecules.

Soft hydrogels obtained by photothermal curing of poly(vinylpyrrolidone)/gold nanoparticles dispersions showing anisotropic swelling and photo-activated antimicrobial properties

Poly(vinylpyrrolidone) (PVP) hydrogels were obtained by green light irradiation of aqueous PVP/ammonium persulfate solutions modified with gold nanoparticles (AuNPs). The increase in temperature produced through the activation of the photothermal effect of AuNPs triggers the decomposition of ammonium persulfate producing radicals that, by attacking the polymer main chain and generating macro-radicals, induce the crosslinking of the polymer via recombination paths. Irradiation from the top of the solutions in an open configuration produced water evaporation and a concomitant increase in temperature during curing, giving rise to dry materials with high aspect ratio and moderate swelling anisotropy. Pads that reversibly adhere to different substrates, including human skin, were produced by simple contact of the final materials with water. Impregnation of gauze wound dressings with PVP-Au-ammonium persulfate dispersions, followed by direct “in situ” photothermal crosslinking, enabled the fabrication of supported functional pads with potential applications as reversible adhesive skin wound dressings. Infusion of the hydrogels with Rose Bengal (RB) provides the materials with photosensitizing properties useful for the photodynamic inactivation of Staphylococcus aureus. A decrease in cell viability of 99.9% was attained after 30 min of irradiation with a low-power green LED source, which demonstrates the efficient singlet oxygen production by RB in the hydrogels and paves the way towards the design of new stimulus-activated bactericidal supplies for biomedical uses.

Every reaction Detail Matters: An in silico driven Step-by-Step Guide to understand the B2O3-Catalyzed CO2 to cyclic carbonates conversion

The catalytic conversion of carbon dioxide (CO2) to cyclic organic carbonates (COCs) via cycloaddition with epoxides offers a dual benefit of reducing CO2 emissions while producing valuable chemical products. In this detailed in silico study, we employ density functional theory (DFT) to meticulously investigate the mechanisms underlying the B2O3/n-NBu4Br-catalyzed cycloaddition of CO2 and epoxides, following a step-by-step approach according to the reaction details. We provide a comprehensive comparison of the non-catalyzed, n-NBu4Br alone, and B2O3/n-NBu4Br-catalyzed pathways, emphasizing two distinct active sites within the B2O3 framework: Site 1 (six-membered boroxol ring) and Site 2 (open chain configuration). Our computational analysis highlights that the Site 1-catalyzed reaction pathway is more favorable, featuring a lower overall energy barrier of 26.8 kcal/mol, compared to 32.5 kcal/mol for the Site 2-catalyzed pathway. Detailed intrinsic bond orbital (IBO), natural adaptive orbital (NAdO) and distortion-interaction analysis (DIA) reveal significant differences in bonding properties and energy interactions, elucidating why Site 1 exhibits superior catalytic activity over Site 2. These findings are corroborated by experimental observations, which indicate that ball milling B2O3 increases defect sites, thereby enhancing exposure of active sites Site 1 and improving catalytic performance. This study provides an in-depth understanding of how the intrinsic properties of boron active sites influence the catalytic efficiency of B2O3, offering valuable insights for the design and optimization of metal-free catalysts for CO2 conversion.

Design of wastewater treatment unit using End-of-Life (EoL) Reverse Osmosis membrane

Abstract Sultanate of Oman is facing severe challenges due to water scarcity, shortage of rainfall, and limited freshwater resources. Over the past few decades, 90% of the natural water resources are consumed by agriculture. Hence, there is an urgent need to find an alternative to obtain fresh water. Water desalination by Reverse Osmosis (RO) is currently practiced in Oman as freshwater source, since it contributes 80% of the total desalination plants installed worldwide. The RO process results in environmental concerns triggered by emission of gases, and discharge of Reverse Osmosis (RO) membranes. The lifespan of membranes depends on the water quality and the operating conditions, and the membrane life is estimated as 5 to 10 years. In order to mitigate the environmental impact for a sustainable desalination output, reuse of discarded end-of-life (EoL) RO membrane is a feasible solution to enhance the water quality. The efficiency of RO membranes is affected by the fouling, scaling, and chemical cleaning for the yearlong operation which lead to reduced salt rejection rate. Hence, this research aimed to reuse the old RO elements by transforming them into Ultrafiltration unit (UF) by removing the active layer and increasing the pore size of membrane. Additionally, modifying the membrane by open configuration and separating all 28 membrane sheets from the permeating tubes are designed as RO-MBR panels. The study shows that, after 5 weeks of operation, the average turbidity rejection rate was 94%, and the average permeated flux per unit was 6.9 LMH. The new configuration shows the permeate flux stability and acceptable BOD, and COD reduction.

A novel preparation of porous Li2TiO3 pebbles with a distinctive structure

Optimization of the pore structure stands out as an effective approach for bolstering the tritium release performance of lithium-based tritium breeding ceramics, particularly when employing a high open porosity configuration. In this study, Li2TiO3 fibers were synthesized via the hydrothermal method, with the assistance of TiO2-B nanowires acting as templates. Subsequently, porous Li2TiO3 pebbles with varying microstructures were fabricated through a combination of the wet method and a sintering process. Sintering process plays a crucial role in determining the microscopic morphology. An increase in temperature resulted in a suppression of the growth of fibrous grains and the transformation of fibrous grains into quasi-spherical grains. Moreover, a two-step sintering process was proposed as a means of improving the crush load (15.9 N vs. 22.0 N) of Li2TiO3 pebbles while simultaneously preserving their high porosity (24.91%). The Li2TiO3 pebbles, produced by the two-step sintering process, exhibited a distinctive micromorphology characterized by interconnected particles forming short rod-shaped microstructures. This distinctive micromorphology contributes to the maintenance of a high degree of open porosity (10.52%).

2D CrSBr Enables Magnetically Controllable Exciton‐Polaritons in an Open Cavity

Abstract 2D van der Waals (vdW) layered materials exhibit significant exciton binding energy and versatile stacking options, making them ideal for room‐temperature exciton‐polariton devices used in low‐threshold lasing, nonlinear optical switching, and quantum computing. However, most existing systems depend on external optical microcavities coupled with single monolayers, leading to limited controllability and increased costs. Here, external cavity‐free vdW magnet CrSBr crystals are presented that feature magnetically controllable self‐hybridized exciton‐polaritons that remain stable up to room temperature. The ultrastrong exciton‐photon coupling suppresses donor‐, phonon‐, and defect‐related emissions. Furthermore, the exciton‐polariton dispersion and emission spectra can be effectively controlled by adjusting the magnetic field, temperature, and CrSBr thickness. This vdW exciton‐polariton material platform, demonstrating remarkable magnetic responsiveness in open cavity configurations under ambient conditions, paves the way for the development of compact, fast, and low‐loss spin, quantum, and magneto‐photonic devices.

Multiresolution molecular dynamics simulations reveal the interplay between conformational variability and functional interactions in membrane-bound cytochrome P450 2B4.

Cytochrome P450 2B4 (CYP 2B4) is one of the best-characterized CYPs and serves as a key model system for understanding the mechanisms of microsomal class II CYPs, which metabolize most known drugs. The highly flexible nature of CYP 2B4 is apparent from crystal structures that show the active site with either a wide open or a closed heme binding cavity. Here, we investigated the conformational ensemble of the full-length CYP 2B4 in a phospholipid bilayer, using multiresolution molecular dynamics (MD) simulations. Coarse-grained MD simulations revealed two predominant orientations of CYP 2B4's globular domain with respect to the bilayer. Their refinement by atomistic resolution MD showed adaptation of the enzyme's interaction with the lipid bilayer, leading to open configurations that facilitate ligand access to the heme binding cavity. CAVER analysis of enzyme tunnels, AquaDuct analysis of water routes, and Random Acceleration Molecular Dynamics simulations of ligand dissociation support the conformation-dependent passage of molecules between the active site and the protein surroundings. Furthermore, simulation of the re-entry of the inhibitor bifonazole into the open conformation of CYP 2B4 resulted in binding at a transient hydrophobic pocket within the active site cavity that may play a role in substrate binding or allosteric regulation. Together, these results show how the open conformation of CYP 2B4 facilitates the binding of substrates from and release of products to the membrane, whereas the closed conformation prolongs the residence time of substrates or inhibitors and selectively allows the passage of smaller reactants via the solvent and water channels.

Power dependent tunable optical nonlinearity in Iron oxide/Borophene core-shell nanoparticles under ultrashort laser excitation

Two-dimensional (2D) nanomaterials find immense applications in ultrafast photonics and optical switching systems due to their fascinating nonlinear optical (NLO) characteristics. This work presents a systematic investigation of laser power-dependent nonlinear optical characteristics of borophene nanosheets in a core-shell nanostructure. For this purpose, we have synthesized Borophene encapsulated Iron oxide (Fe3O4) core-shell nanoparticles (Fe3O4/Borophene CSNPs). The CSNPs were synthesized by mixing and annealing sodium borohydride (NaBH4) as a boron precursor with iron oxide nanoparticles (Fe3O4 NPs) in a controlled environment using chemical vapor deposition technique (CVD) followed by characterization using XRD, FTIR Spectroscopy, UV–vis absorption spectroscopy, TEM, SEM, and EDX techniques. Magnetic properties were analyzed by a vibrating sample magnetometer (VSM) which shows that the saturation magnetization of Fe3O4 NPs increases after being encapsulated in borophene nanosheets. The role of borophene in modifying the NLO characteristics of Fe3O4/Borophene CSNPs was studied using a power-dependent Z-scan technique utilizing ultrashort (femtosecond) laser pulses at a wavelength of 800 nm in both open and close aperture configuration. It was found that borophene-coated Fe3O4 NPs reveal tunable NLO properties that resemble the NLO characteristics of borophene nanosheets with enhanced features. This provides insights into an interaction between materials in NLO phenomena and illustrates the distinctive performance of the core-shell nanostructure. The tunable NLO properties of Fe3O4/Borophene CSNPs offer an innovative approach for developing optoelectronics and ultrafast nonlinear photonic devices.

Centrifugal Compressor Surge in Closed Loop Systems: Initial Modelling and Comparison with Experiments

Abstract Heat pumps are expected to play a primary role in electrification of thermal users in the residential and industrial sectors. Dynamic compressors are widely used in large size heat pumps, thanks to their industrial replicability, compact size, affordable costs, and good performance in terms of efficiency and low acoustic emissions. The instability, which may occur in a compressor installed in closed loop cycle such as in a heat pump, is quite different from the classic open loop configuration involving dynamic compressors. This is mainly due to the complexity of the compressor instability mechanism coupled to a vapor compression system connected with two- phase heat exchangers, having different thermal and fluid dynamic capacitance properties, under a physical feedback loop. The aim of this paper is to investigate the behaviour of a dynamic compressor installed in an innovative heat pump prototype, of laboratory scale, under stable and unstable conditions. A preliminary simple dynamic model of the compression system consisting of a radial compressor, condenser and evaporator, is developed to represent the heat pump compression system, which can capture the unstable behaviour. The evaporator and condenser are modelled using empirical correlations. The preliminary validation of the dynamic model results is done through a dedicated experimental campaign, under different operating conditions. Results show the complexity of the interaction between the centrifugal compressor and the heat pump loop, discerning the different contributions to the time-dependent response of the system, prompting the necessity of a detailed model in the next step of the work.

Structural Analyses of a GABARAP~ATG3 Conjugate Uncover a Novel Non-covalent Ubl-E2 Backside Interaction.

Members of the ATG8 family of ubiquitin-like proteins (Ubls) are conjugated to phosphatidylethanolamine (PE) in the autophagosomal membrane, where they recruit degradation substrates and facilitate membrane biogenesis. Despite this well-characterized function, the mechanisms underlying the lipidation process, including the action of the E2 enzyme ATG3, remain incompletely understood. Here, we report the crystal structure of human ATG3 conjugated to the mammalian ATG8 protein GABARAP via an isopeptide bond, mimicking the Ubl~E2 thioester intermediate. In this structure, the GABARAP~ATG3 conjugate adopts an open configuration with minimal contacts between the two proteins. Notably, the crystal lattice reveals non-covalent contacts between GABARAP and the backside of ATG3's E2 catalytic center, resulting in the formation of a helical filament of the GABARAP~ATG3 conjugate. While similar filament formations have been observed with canonical Ub~E2 conjugates, the E2 backside-binding interface of GABARAP is distinct from those of Ub/Ubl proteins and overlaps with the binding site for LC3 interacting region (LIR) peptides. NMR analysis confirms the presence of this non-covalent interaction in solution, and mutagenesis experiments demonstrate the involvement of the E2 backside in PE conjugation. These findings highlight the critical role of the E2 backside in the lipidation process and suggest evolutionary adaptations in the unique E2 enzyme ATG3.

Evaluation of the Impact of Stress Distribution on Polyurethane Trileaflet Heart Valve Leaflets in the Open Configuration by Employing Numerical Simulation

It is costly and time-consuming to design and manufacture functional polyurethane heart valve prototypes, to evaluate and comprehend their hemodynamic behaviour. To enhance the rapid and effective design of replacement heart valves, to meet the minimum criteria of FDA and ISO regulations and specifications, and to reduce the length of required clinical testing, computational fluid dynamics (CFD) and finite element analysis (FEA) were used. The results revealed that when the flexibility of the stent was taken into consideration with a uniform leaflet thickness, stress concentration regions that were present close to the commissural attachment were greatly diminished. Furthermore, it was found that the stress on the leaflets was directly impacted by the effect of reducing the post height on both rigid and flexible stents. When varying the leaflet thickness was considered, the high-stress distribution close to the commissures appeared to reduce at thicker leaflet regions. However, thicker leaflets may result in a stiffer valve with a corresponding increase in pressure drop. It was concluded that a leaflet with predefined varying thickness may be a better option.

Three-dimensional vibration analysis of multilayered composite and functionally graded piezoelectric plates and shells

In the present paper, a coupled 3D exact electro-elastic shell model for Functionally Graded (FG) and composite piezoelectric structures is proposed. Primary variables of the electro-elastic model are the electric potential and the three displacement components. The model allows to evaluate the piezoelectric effect in terms of frequencies and vibration modes. Both closed and open circuit configurations are analyzed and compared. The 3D equilibrium equations and the 3D divergence electric displacement equation for spherical shells give the set of partial differential equations for the electro-elastic problem. The proposed model for spherical shells automatically degenerates into simpler models for plates and cylindrical shells via properly considerations on radii of curvature along in-plane directions. The orthogonal mixed curvilinear coordinates α, β and z are employed. The partial differential governing equations have constant coefficients considering fictitious layers and they are solved using the Navier harmonic form and the exponential matrix method. These features lead to an exact solution for simply-supported boundary conditions. Free vibration analyses are conducted and circular frequencies for the first three thickness vibration modes are computed. After a global assessment phase to verify the correctness of the developed model, new benchmarks are proposed: different thickness ratios and material configurations are investigated. The present work can be intended as a reference general solution for those scientists interested in the study of piezoelectric structures via 2D analytical and numerical formulations.

Evaluation of airborne transmission of respiratory contaminants in a passenger car cabin with window opening

Exhaled aerosols can be suspended in the air for long periods, facilitating the transmission of highly infectious respiratory diseases. The risk of exposure to occupants varies due to different usage conditions and driving scenarios of moving vehicles. Therefore, the present study investigates the airborne transmission of contaminants generated by coughing in a moving vehicle and explores the relationship between aerosol dispersion and fluid exchange between the interior and exterior domains of the car under the influence of window opening configurations, seating layouts and driving speeds. The results show that the cross-opening configurations provide a superior contaminant removal efficiency. The effect of seating layout on removal efficiency is significant, although it has a slight effect on air change rate (ACH). The best removal efficiency can be obtained when the passenger sits in the front seat with the right front window opening. Furthermore, the in-cabin ACH is almost linearly correlated with the driving speed. Higher speeds reduce contaminant concentrations faster. However, the risk of driver exposure does not depend solely on ACH, the peak cumulative contaminant concentration and residence time also need to be considered. This study offers data for the prevention and control of respiratory infectious diseases.

The crystal structure of Shethna protein II (FeSII) from Azotobacter vinelandii suggests a domain swap.

The Azotobacter vinelandii FeSII protein forms an oxygen-resistant complex with the nitrogenase MoFe and Fe proteins. FeSII is an adrenodoxin-type ferredoxin that forms a dimer in solution. Previously, the crystal structure was solved [Schlesier et al. (2016), J. Am. Chem. Soc. 138, 239-247] with five copies in the asymmetric unit. One copy is a normal adrenodoxin domain that forms a dimer with its crystallographic symmetry mate. The other four copies are in an `open' conformation with a loop flipped out exposing the 2Fe-2S cluster. The open and closed conformations were interpreted as oxidized and reduced, respectively, and the large conformational change in the open configuration allowed binding to nitrogenase. Here, the structure of FeSII was independently solved in the same crystal form. The positioning of the atoms in the unit cell is similar to the earlier report. However, the interpretation of the structure is different. The `open' conformation is interpreted as the product of a crystallization-induced domain swap. The 2Fe-2S cluster is not exposed to solvent, but in the crystal its interacting helix is replaced by the same helix residues from a crystal symmetry mate. The domain swap is complicated, as it is unusual in being in the middle of the protein rather than at a terminus, and it creates arrangements of molecules that can be interpreted in multiple ways. It is also cautioned that crystal structures should be interpreted in terms of the contents of the entire crystal rather than of one asymmetric unit.

Optimizing wind-catching butterfly roofs to improve cross natural ventilation performance in apartment buildings

Abstract This study aims to enhance cross natural ventilation performance in multi-level double-loaded apartments by employing a wind-catching butterfly roof, specifically designed for apartments with a center-to-center opening configuration. A 2k full-factorial design of experiment (DOE) method with a center point is utilized for design optimization. Nine configurations, determined by roof height h and roof angle α, are assessed using Computational Fluid Dynamics (CFD). After the initial DOE assessment, three additional butterfly roof designs with varying α values are explored. The dimensionless flow rate (DFR) serves as the objective function for optimization. The optimal design features a butterfly roof with h = 0.01m and α = 30°, demonstrating improvements of 2.5%−4.9% in DFR and 5.3%−9.0% in the pressure coefficient C p compared to scenarios without a butterfly roof. Butterfly roofs also increased the velocity magnitudes in the rooms of the leeward block, with configurations h = 0.01m and α = 35° and 37.5° showing the most significant increases of 58.5% − 86.9% on levels 1 to 3. The discharge coefficient C d induced by all butterfly roof configurations are within 0.6 − 0.7 on levels 1 to 3, while the C d values for levels 4 to 6 are within 0.5 − 0.6. Although butterfly roofs can enhance indoor air quality, they require further research to meet all recommended guidelines. These findings provide valuable insights for architects and urban planners aiming to reduce the environmental footprint of apartment buildings. This research presents a comprehensive evaluation of the potential of butterfly roofs to enhance apartment ventilation and offers recommendations for future design improvements.

Effect of diastereoisomeric composition on the chromatographic retention of phosphorothioated oligonucleotides using three different liquid chromatography systems

To increase understanding of the interactions and effects of the diastereoisomeric character of phosphorothioate (PS) oligonucleotides on chromatographic retention, three chromatographic methods [in-series reversed phase-strong anion exchange (RP-SAX), ion pair-reversed phase and metal ion complexation chromatography (MICC)] were applied to the characterization of stereo-enriched compounds. Chromatographic systems are widely available, amenable to routine applications, and simple to deploy in comparison to more advanced instrumentation (e.g., 31P NMR) and procedures (e.g., enzymatic digestion). Analogous diastereoisomeric distribution profiles were obtained by RP-SAX and IP-RP based on their common mechanism of separation involving the combination of hydrophobic and electrostatic interactions. Similar linear relationships between retention time (tR) and the numbers of stereo random, Rp, and Sp PS linkages were obtained with both methods. Sp-enriched diastereoisomers were retained longer than stereo random and Rp-enriched diastereoisomers. MICC produced much broader diastereoisomeric peak distributions than the other two methods due to its more complicated nature of interaction. Average mass spectra showed a smaller number of Ag ions (1-7) complex with early eluting diastereoisomers than with later eluting diastereoisomers (which complex between 6-12 Ag ions). A higher late-to-early peak UV area ratio was obtained for a sample containing 10 Sp linkages vs one containing 10 Rp linkages pointing to the tendency of the Sp diastereoisomers for increased interactions which could be explained by structures with more open or stretched configurations. Consideration of the peak shapes of the MICC distributions led to comparable hierarchical cluster analysis (HCA) classification to that produced by the IP-RP method, indicating a good orthogonality between the two methods. Preliminary analysis of the data using partial least squares showed that it should be possible to determine the diastereoisomeric composition of PS oligonucleotides from chromatographic data following appropriate data training.

Numerical Analysis of the Effects of Different Window-Opening Strategies on the Indoor Pollutant Dispersion in Street-Facing Buildings

The idling of automobiles at street intersections can lead to pollutant accumulation which impacts the health of residents in street-facing buildings. Previous research focused on pollutant dispersion within street canyons and did not consider the coupling of indoor and outdoor pollutants. This paper employs the computational fluid dynamics (CFD) method to simulate the dispersion characteristics of vehicle emission pollutants in street canyons, primarily investigating the indoor and outdoor pollutant dispersion patterns under various window opening configurations (single-sided ventilation, corner ventilation, and different positions of the glass under corner ventilation). Additionally, the study considers the impacts of the aspect ratio and ambient wind speed. Studies have shown that corner ventilation is effective in reducing indoor pollutant levels. When the two window glass positions are far away from the center of the intersection, the average CO mass fraction in the single-sided ventilation room is reduced by 87.1%. The average indoor CO mass fraction on the leeward side decreases with the increasing wind speed and aspect ratio. At a wind speed of 8 m/s, the average indoor CO mass fraction on the leeward side decreases to 2.45 × 10−8. At an aspect ratio of 2, the indoor CO mass fraction on the leeward side decreases with increasing floors before stabilizing at approximately 4.77 × 10−9. This study suggests optimal window opening strategies to reduce indoor pollutant levels in street-facing buildings at street intersections, offering guidance to indoor residents on window ventilation practices.

Open Retromuscular Sugarbaker vs Keyhole Mesh Placement for Parastomal Hernia Repair

Durable parastomal hernia repair remains elusive. There is limited evidence comparing the durability of the open retromuscular Sugarbaker and keyhole mesh configurations. To determine if the open retromuscular Sugarbaker mesh placement technique would lower parastomal hernia recurrence rates. In this single-center, randomized clinical trial, 150 patients with a permanent stoma and associated parastomal hernia who were candidates for open retromuscular parastomal hernia repair were enrolled and randomized from April 2019 to April 2022 and followed up for 2 years. Following intraoperative assessment to determine the feasibility of either technique, enrolled patients were randomized to receive either retromuscular Sugarbaker or keyhole synthetic mesh placement. The primary outcome was parastomal hernia recurrence at 2 years. Secondary outcomes included mesh-related complications, wound complications, reoperations, as well as patient-reported pain, abdominal wall-specific quality of life, stoma-specific quality of life, and decision regret at 1 year and 2 years. A total of 150 patients were randomized, and with 91% follow-up at 2 years, there were 13 (17%) parastomal hernia recurrences in the retromuscular Sugarbaker arm and 18 (24%) in the keyhole arm (adjusted risk difference, -0.029; 95% CI, -0.17 to 0.153, and adjusted risk ratio, 0.87; 95% CI, 0.42 to 1.69). There were no statistically significant differences between the Sugarbaker and keyhole groups regarding reoperations for recurrence (2 vs 7, respectively), nonhernia intra-abdominal pathology (4 vs 10, respectively), stoma necrosis (1 vs 0, respectively), mesh-related complications (4 vs 1, respectively), patient-reported pain, abdominal wall-specific quality of life, stoma-specific quality of life, and decision regret at any time point. In the setting of open parastomal hernia repair, a retromuscular Sugarbaker mesh placement technique was not superior to a keyhole configuration 2 years after repair. Further innovation is necessary to improve parastomal hernia repair outcomes. ClinicalTrials.gov Identifier: NCT03972553.