Multiple Formation Research Articles

Chlorine levels and a Legionella outbreak

Background: Legionella, first identified in the 1970s, is increasingly recognized as an opportunistic pathogen in healthcare facilities.1 The National University Hospital (NUH) is a large quaternary level academic hospital with 1,200 beds located in equatorial Singapore. Its first building, completed in 1985, still serves patients today. In 2022, the infection prevention team (IPT) was informed of two cases of nosocomial legionella, which sparked the start of an extensive investigation consisting of water quality testing of multiple sources, case finding, and formation of a water management committee. Methods: 250mL water samples were collected and cultured by an external vendor using direct membrane filtration followed by plating on selective agar according to ISO 11731 standards. Bacterial colonies were then identified, quantified and speciated. At the same time, NUH’s facility management measured chlorine levels using a portable colorimeter. Results: In total, we cultured 34 samples taken from sinks, shower heads, potable water dispensers. 91.2% of samples were positive for legionella. Of the 91.2%, 35.3% of sites grew Legionella pneumophila serogroup 1 while 79.4% of sites grew Legionella pneumophila serogroup 2-15. We attributed our high rates of legionella positivity to an aging plumbing system and Singapore’s high humidity and temperatures. In addition, the maximal temperature of our hot water is only 48-50 °C. Although chlorine levels were generally low, they were still within the local recommendation of less than 2ppm (Singapore does not have guidance on minimum chlorine levels). We found no statistically significant correlation between the number of legionella colony forming units (CFUs) and chlorine levels (ranging between 0.02 to 0.14ppm). This supports the United States Environmental Protection Agency’s recommendation, as well as the findings from in vitro and in vivo studies, for a minimal chlorine of 0.2 PPM at the taps for acute care hospitals.2,3However, these levels may be inadequate in the presence of acanthamoeba or a high biofilm load within water systems.4,5 Conclusion: Hospital water management programs should require a minimal level of chlorine at hospital taps and at levels above those recommended by public water systems, in order to control legionella growth. In addition, the formation of a hospital water management committee is essential to improve hospital water quality and put mitigation measures in place.

Features of Bone Mineral Density, Calcium-Phosphorus Metabolism and Bone Remodeling in Patients with Systemic Lupus Erythematosus

Introduction. Systemic lupus erythematosus (SLE) is a complex autoimmune disease with variable clinical manifestations associated with multiple autoantibodies formation and deposition of immune complexes, and other immune processes. Despite significant advances in treatment, the disease remains disabling, in particular, due to increased bone fragility and low-energy fractures. The study of bone remodeling in patients with SLE should help to improve the therapy and quality of their treatment. The aim of the study. To investigate the features of bone mineral density, calcium-phosphorus metabolism and bone remodeling in patients with systemic lupus erythematosus. Materials and methods. The study involved 123 women with SLE aged 21-51 years. The comparison group (CG) consisted of 25 women without SLE in premenopausal status of the appropriate age. The control group included 25 practically healthy women. In order to study bone mineral density (BMD), dual-energy X-ray densitometry (DXA) of the lumbar spine was performed using a dual-energy X-ray absorptiometer. For the study of calcium-phosphorus metabolism (CPM), total calcium (Ca), ionized Ca, phosphorus (P) in blood and Ca, P, creatinine in daily urine, as well as parathyroid hormone (PTH) and 25-hydroxyvitamin D in serum were determined. Markers of bone remodeling (osteocalcin, procollagen type 1 amino-terminal propeptide (P1NP) and isomerized C-terminal telopeptide (β-crosslaps) in serum were measured. To achieve the stated goal, the first step included the determination of bone damage prevalence in patients with the diagnosed SLE; the second step was directed towards the characterization the particular bone condition in patients with SLE based on the results of BMD, CPM indices and markers of bone remodeling assessment. Results and discussion. According to the results of DXA of the lumbar spine, 88 (71.54 %) women of the SG and only 8 (32.00 %) women of the CG had a decrease in BMD (p < 0.001). According to the mean values, the studied CPM indices of the SG patients, CG and control group wemen exposed no significant differences. Similarly, no significant differences were detected in the mean values of urinary phosphorus and in between blood PTH values in SG, CG, and control. The level of 25-hydroxyvitamin D was significantly lower in SG (15.14 ± 0.80 ng/ml) than in CG (19.62 ± 0.46 ng/ml) and control (22.38 ± 1.34 ng/ml) p < 0.05. The mean value of osteocalcin in woman with SLE was significantly lower than in CG and control (11.81 ± 0.49 ng/ml versus 18.61 ± 0.75 ng/ml and 19.28 ± 1.88, p < 0.001). No significant difference were detected in between the mean values of P1NP in SG, CG and control. The mean values of β-cross laps were significantly higher in patients with SLE (0.51 ± 0.02 ng/ml) compared to GC (0.26 ± 0.02 ng/ml) and control (0.28 ± 0.02 ng/ml), p < 0.001. Conclusions. Bone mineral density, calcium-phosphorus metabolism and bone remodeling in patients with systemic lupus erythematosus have peculiarities as follows: a significant decrease in bone mass in 71.54 % of patients, namely 18, 70 % - grade I osteopenia, 21.14 % - grade II osteopenia, 14.63 % - grade III osteopenia; 17.07 % - osteoporosis, increased calcium excretion, vitamin D deficiency, decreased osteoblastic and enhansed osteoclastic functions.

Adaptive position control using backstepping technique for the leader‐follower multiple quadrotor unmanned aerial vehicle formation

SummaryThis article addresses the position control issue of multi‐quadrotor unmanned aerial vehicle (QUAV) formation. Concerning the translational dynamic of a multi‐QUAV system, on the one hand, it is an under‐actuation dynamic; on the other hand, it does not satisfy the matching condition. These features will cause inevitable thorny in the formation position control design. Furthermore, because of the state coupling problem, the formation control of multi‐QUAV system is more challenging and knotty than the control of single QUAV system. To achieve this control, both backstepping technique and neural network (NN) approximation strategy are combined by introducing an intermediary control, where NN is employed to compensate the system uncertainty. However, since the traditional adaptive NN control methods need to train a large number of adaptive parameters for the high approximation accuracy, it will cause the heavy computing burden if traditional adaptive method is used for the QUAV formation control. The proposed adaptive NN strategy in this paper only requires training a scalar adaptive parameter, which is generated from the norm of NN weight vector or matrix, thereby significantly reducing computational burden. Finally, according to Lyapunov stability proof and computer simulation, it is demonstrated that the control tasks can be successfully accomplished.

Severe necrotizing tracheobronchitis caused by influenza B and methicillin-resistant Staphylococcus aureus co-infection in an immunocompetent patient

Purpose and methodNecrotizing tracheobronchitis is a rare clinical entity presented as a necrotic inflammation involving the mainstem trachea and distal bronchi. We reported a case of severe necrotizing tracheobronchitis caused by influenza B and methicillin-resistant Staphylococcus aureus (MRSA) co-infection in an immunocompetent patient.Case presentationWe described a 36-year-old man with initial symptoms of cough, rigors, muscle soreness and fever. His status rapidly deteriorated two days later and he was intubated. Bronchoscopy demonstrated severe necrotizing tracheobronchitis, and CT imaging demonstrated multiple patchy and cavitation formation in both lungs. Next-generation sequencing (NGS) and bronchoalveolar lavage fluid (BALF) culture supported the co-infection of influenza B and MRSA. We also found T lymphocyte and NK lymphocyte functions were extremely suppressed during illness exacerbation. The patient was treated with antivirals and antibiotics including vancomycin. Subsequent bronchoscopy and CT scans revealed significant improvement of the airway and pulmonary lesions, and the lymphocyte functions were restored. Finally, this patient was discharged successfully.ConclusionNecrotizing tracheobronchitis should be suspected in patients with rapid deterioration after influenza B infection. The timely diagnosis of co-infection and accurate antibiotics are important to effective treatment.

In silico investigation of the formation of multiple intense zebra stripes using extending domain

We perform an in silico investigation of the formation of multiple intense zebra stripes by extending the domain with an appropriate extending speed. The common zebra has alternating dark and light stripes, creating a two phase pattern. However, some Equus burchelli zebras have an intermediate gray color stripe situated between the dark and light stripes. To numerically investigate the formation of multiple intense zebra stripes, we first find the equilibrium state of the governing system in the one-dimensional (1D) static domains using various frequency modes. After finding the equilibrium state for the governing system in the 1D static domains, we stack a numerical data. Then, we load the stacked numerical data to use as an initial state for finding the growth rate that forms the multiple intense zebra stripe formation in the 1D extended domains. Next, convergence experiments are conducted to verify the convergence of the numerical method for the governing system. Finally, numerical simulations are performed to confirm the formation of multiple intense zebra stripes in two-dimensional extending domains and on evolving curved surfaces.

Sustainable Synthesis through Catalyst-Free Photoinduced Cascaded Bond Formation.

The beginning of photochemical reactions revolutionized synthetic chemistry through sustainable practices. This review explores cutting-edge developments in leveraging light-induced processes for generating cascaded C-C and C-hetero bonds without catalysts. Significantly, catalyst-free photoinduced methodologies have garnered considerable attention, especially in the creation of varied heterocyclic frameworks for drug design and the synthesis of natural products. The article delves into underlying mechanisms, addresses limitations, and evaluates various methodologies, emphasizing the potential of photocatalyst and transition metal-free photochemical reactions to enhance sustainability. Divided into two sections, it covers recent strides in C-C and C-heteroatom and multiple C-heteroatom bond formation reactions.

Generation of abnormal distributions of inter- and intramolecular δ13C compositions in hydrocarbons from gold tube pyrolysis of an Australian torbanite

Abnormal stable carbon isotopic (δ13C) compositions, deviating from the conventional order of δ13C1 < δ13C2 < δ13C3, are frequently observed in natural gas reservoirs. For thermogenic gas, these anomalies, such as δ13C1 < δ13C3 < δ13C2 or δ13C1 > δ13C2 > δ13C3, have multiple formation mechanisms including gas mixing in conventional systems and desorption processes of gaseous hydrocarbons in unconventional shale gas systems due to their inconsistency with Rayleigh fractionation processes. Considering distinct reaction pathways (e.g., C1 polymerized to C2), these aberrant δ13C signatures are often construed as intrinsic hallmarks of extensively evolved natural gas. However, on the basis of gas generation simulation, not all findings exhibit abnormal δ13C values, hinting at multifaceted and intricate mechanisms governing the isotopic fractionation of alkane gas components. This study conducted gold tube pyrolysis of an Australian torbanite, revealing four distinct types of δ13C anomalies in hydrocarbon classes. Polycyclic aromatic hydrocarbons (PAHs) exhibited δ13C values more negative than co-occurring n-alkanes. δ13C3 displayed a negative trend shift from EasyRo = 3.5 %, resulting in a partially δ13C-reversed gas (δ13C1 < δ13C3 < δ13C2) formed at EasyRo ≈ 4.1 %. Moreover, intramolecular δ13C3 (both terminal and central carbons, termed δ13Ca and δ13Cb, respectively) reversed alongside the overall δ13C3 trend. Additionally, the evolution of site preference in δ13C3 (termed ‰SP = δ13Ca – δ13Cb) transitioned from progressively negative to positive. The results of this study demonstrate that the potential conversion between saturated hydrocarbons, aromatic hydrocarbons, and alkane gases is at least partially responsible for δ13C anomalies, but also that gaseous hydrocarbons formed from other fractions at high maturity cannot be ruled out, such as kerogen and pyrobitumen.

An Enhanced Multiple Unmanned Aerial Vehicle Swarm Formation Control Using a Novel Fractional Swarming Strategy Approach

This paper addresses the enhancement of multiple Unmanned Aerial Vehicle (UAV) swarm formation control in challenging terrains through the novel fractional memetic computing approach known as fractional-order velocity-pausing particle swarm optimization (FO-VPPSO). Existing particle swarm optimization (PSO) algorithms often suffer from premature convergence and an imbalanced exploration–exploitation trade-off, which limits their effectiveness in complex optimization problems such as UAV swarm control in rugged terrains. To overcome these limitations, FO-VPPSO introduces an adaptive fractional order β and a velocity pausing mechanism, which collectively enhance the algorithm’s adaptability and robustness. This study leverages the advantages of a meta-heuristic computing approach; specifically, fractional-order velocity-pausing particle swarm optimization is utilized to optimize the flying path length, mitigate the mountain terrain costs, and prevent collisions within the UAV swarm. Leveraging fractional-order dynamics, the proposed hybrid algorithm exhibits accelerated convergence rates and improved solution optimality compared to traditional PSO methods. The methodology involves integrating terrain considerations and diverse UAV control parameters. Simulations under varying conditions, including complex terrains and dynamic threats, substantiate the effectiveness of the approach, resulting in superior fitness functions for multi-UAV swarms. To validate the performance and efficiency of the proposed optimizer, it was also applied to 13 benchmark functions, including uni- and multimodal functions in terms of the mean average fitness value over 100 independent trials, and furthermore, an improvement at percentages of 29.05% and 2.26% is also obtained against PSO and VPPSO in the case of the minimum flight length, as well as 16.46% and 1.60% in mountain terrain costs and 55.88% and 31.63% in collision avoidance. This study contributes valuable insights to the optimization challenges in UAV swarm-formation control, particularly in demanding terrains. The FO-VPPSO algorithm showcases potential advancements in swarm intelligence for real-world applications.

A stream come true: Connecting tidal tails, shells, streams, and planes with galaxy kinematics and formation history

Context. The rapidly improving quality and resolution of both low surface brightness observations and cosmological simulations of galaxies enable us to address the important question of how the formation history is imprinted in the outer unrelaxed regions of galaxies, and to inspect the correlations of these imprints with another tracer of galaxy formation, the internal kinematics. Aims. Using the hydrodynamical cosmological simulation called Magneticum Pathfinder, we identified tidal tails, shells, streams, and satellite planes, and connected them to the amount of rotational support and the formation histories of the host galaxies. This presents the first combined statistical census considering all these four types of features in hydrodynamical cosmological simulations. Methods. Tidal features were visually classified from a three-dimensional rendering of the simulated galaxies by several scientists independently. Only features that were identified by at least half of the participating individuals were considered to be existing features. The data on satellite planes and kinematic properties of the simulated galaxies were taken from previous work. The results were compared to observations, especially from the MATLAS survey. Results. Generally, prominent features are much more common around elliptical than around disk galaxies. Shells are preferentially found around kinematically slowly rotating galaxies in both simulations and observations, while streams can be found around all types of galaxies, with a slightly higher probability to be present around less rotationally supported galaxies. Tails and satellite planes, however, appear independently of the internal kinematics of the central galaxy, indicating that they are formed through processes that have not (yet) affected the internal kinematics. Prolate rotators have the overall highest probability to exhibit tidal features, but the highest likelihood for a specific type of feature is found for galaxies with kinematically distinct cores (KDCs), nearly 20% of which exhibit streams. Conclusions. As shells are formed through radial merger events while streams are remnants of circular merger infall, this suggests that the orbital angular momentum of the merger event plays a more crucial role in transforming the host galaxy than previously anticipated. The existence of a shell around a given slow rotator furthermore is a sign of a radial merger formation for this particular slow rotator because one-third of the galaxies with a shell were transformed into slow rotators by the merger event that also caused the shells. The appearance of a stream around a KDC is a direct indicator for the multiple merger formation pathway of that KDC as opposed to the major merger pathway.

Cooperative control method of multiple spacecraft formation based on graphtheory

Spacecraft cluster is a new way of multi-vehicle cooperation and a major problem in the current space distribution system. A large number of core technologies of spacecraft cluster technology need to be simulated, analyzed and verified on the ground. On this basis, this article proposes the construction of a spacecraft system model and a dynamic model, and designs a path planning method that combines the spacecraft system model with the a* algorithm. And use the Morphin search tree algorithm to improve the A-star algorithm, and then simulate and analyze the spacecraft formation control scheme. The simulation results of trajectory planning show that after running the model for 21 ms, the improved A* algorithm achieved the expected error. Its MAE value is 10 - 4, achieving good path planning effect. The research plan can effectively achieve control of spacecraft formation and meet the needs of collaborative tasks and navigation route planning.

EMM-Promoted Pd-Catalyzed Solid State Intramolecular Heck-Type Cyclization/Boronation and Suzuki Couplings: Access to Functionalized Indolines.

EMM (electromagnetic mill)-promoted Pd-catalyzed solid state intramolecular Heck-type cyclization/boronation and Suzuki couplings are reported. Compared to previous mechanochemistry that constructed one chemical bond through a cross-coupling reaction, this strategy realizes cascade transformation along with multiple chemical bond formation. This conversion does not require organic solvents or additional heating, and it shows a good substrate scope and high functional group tolerance.

PH-responsive bioadhesive with robust and stable wet adhesion for gastric ulcer healing

Development of bioadhesives that can be facilely delivered by endoscope and exhibit instant and robust adhesion with gastric tissues to promote gastric ulcer healing remains challenging. In this study, an advanced bioadhesive is prepared through free radical polymerization of ionized N-acryloyl phenylalanine (iAPA) and N-[tris (hydroxymethyl) methyl] acrylamide (THMA). The precursory polymer solution exhibits low viscosity with the capability for endoscope delivery, and the hydrophilic-hydrophobic transition of iAPA upon exposure to gastric acid can trigger gelation through phenyl groups assisted multiple hydrogen bonds formation and repel water molecules on tissue surface to establish favorable environment for interfacial interactions between THMA and functional groups on tissues. The in-situ formed hydrogel features excellent stability in acid environment (14 days) and exhibits firm wet adhesion to gastric tissue (33.4 kPa), which can efficiently protect the wound from the stimulation of gastric acid and pepsin. In vivo studies reveal that the bioadhesive can accelerate the healing of ulcers by inhibiting inflammation and promoting capillary formation in the acetic acid-induced gastric ulcer model in rats. Our work may provide an effective solution for the treatment of gastric ulcers clinically.

Pathway-divergent coupling of 1,3-enynes with acrylates through cascade cobalt catalysis

Catalytic cascade transformations of simple starting materials into highly functionalized molecules bearing a stereochemically defined multisubstituted alkene, which are important in medicinal chemistry, natural product synthesis, and material science, are in high demand for organic synthesis. The development of multiple reaction pathways accurately controlled by catalysts derived from different ligands is a critical goal in the field of catalysis. Here we report a cobalt-catalyzed strategy for the direct coupling of inexpensive 1,3-enynes with two molecules of acrylates to construct a high diversity of functionalized 1,3-dienes containing a trisubstituted or tetrasubstituted olefin. Such cascade reactions can proceed through three different pathways initiated by oxidative cyclization to achieve multiple bond formation in high chemo-, regio- and stereoselectivity precisely controlled by ligands, providing a platform for the development of tandem carbon-carbon bond-forming reactions.

QUINQUAUD’S DISEASE IN THE SPECTRUM OF CONCOMITANT DERMATOLOGIC PATHOLOGY

Cicatrical alopecia is one of the acute issues of modern dermatology due to a permanent cosmetic defect in the form of bald areas with non-recoverable loss of hair follicles. Interrelation of cicatrical alopecia with other dermatoses and somatic diseases is also topical. The article presents a clinical case of development of Quinquaud’s disease of the scalp combined with parapsoriasis lichenoides and multiple seborrheic keratosis on the top of already administered targeted therapy in connection with previously removed skin melanoma. Among the features of this pathology, we noted: appearance of rashes after a past oncological disease, erythema diffusely spreading throughout the entire scalp, multiple follicular pustules and rapid formation of cicatricial atrophy, severe itching and soreness, resistance to the ongoing therapy, as well as multiple rashes on the skin of body and extremities in the form of lichenoid papules and plaques. For differential diagnostics, multifocal biopsic examination of the skin was carried out, which showed presence of histologic signs of three dermatoses, which make up a spectrum of the concomitant pathology in the patient. Taking into account the important role of staphylococcal infection in the pathogenesis of Quinquaud’s disease and parapsoriasis lichenoides, we can assume similar pathogenetic mechanisms for the development of these diseases in the patient, associated with disorders of cutaneous microbiome. It is possible that a history of the oncological pathology and targeted therapy could lead to a decrease in resistance and suppression of the immune system, which was also a factor contributing to the development of concomitant dermatoses. Appearance of multiple eruptive seborrheic keratomas on skin of the body and extremities may be an indicator of a paraneoplastic process and require oncological screening. Understanding the causes and common factors of formation of dermatoses comorbid with cicatricial alopecia is extremely important for a dermatologist, because it allows performing early diagnostics in a timely manner, assigning treatment and preventing development of the permanent cosmetic defect leading to a decrease in the quality of life.

QUINQUAUD’S DISEASE IN THE SPECTRUM OF CONCOMITANT DERMATOLOGIC PATHOLOGY

Cicatrical alopecia is one of the acute issues of modern dermatology due to a permanent cosmetic defect in the form of bald areas with non-recoverable loss of hair follicles. Interrelation of cicatrical alopecia with other dermatoses and somatic diseases is also topical. The article presents a clinical case of development of Quinquaud’s disease of the scalp combined with parapsoriasis lichenoides and multiple seborrheic keratosis on the top of already administered targeted therapy in connection with previously removed skin melanoma. Among the features of this pathology, we noted: appearance of rashes after a past oncological disease, erythema diffusely spreading throughout the entire scalp, multiple follicular pustules and rapid formation of cicatricial atrophy, severe itching and soreness, resistance to the ongoing therapy, as well as multiple rashes on the skin of body and extremities in the form of lichenoid papules and plaques. For differential diagnostics, multifocal biopsic examination of the skin was carried out, which showed presence of histologic signs of three dermatoses, which make up a spectrum of the concomitant pathology in the patient. Taking into account the important role of staphylococcal infection in the pathogenesis of Quinquaud’s disease and parapsoriasis lichenoides, we can assume similar pathogenetic mechanisms for the development of these diseases in the patient, associated with disorders of cutaneous microbiome. It is possible that a history of the oncological pathology and targeted therapy could lead to a decrease in resistance and suppression of the immune system, which was also a factor contributing to the development of concomitant dermatoses. Appearance of multiple eruptive seborrheic keratomas on skin of the body and extremities may be an indicator of a paraneoplastic process and require oncological screening. Understanding the causes and common factors of formation of dermatoses comorbid with cicatricial alopecia is extremely important for a dermatologist, because it allows performing early diagnostics in a timely manner, assigning treatment and preventing development of the permanent cosmetic defect leading to a decrease in the quality of life.

A Case of a Patient with Combined Diabetic Peripheral Neuropathy and Peripheral Vasculopathy Who Achieved Healing After Combined Multidisciplinary Outpatient Treatment of the Diabetic Foot

Diabetic foot ulcer is one of the serious complications of diabetes, which is a chronic wound caused by a combination of factors such as limb ischemia, infection, lower limb neuropathy, etc. Its treatment and wound management pose significant challenges to all healthcare professionals. Currently, treatment for diabetic foot ulcers often focuses on surgical interventions such as skin grafting and amputation, significantly impacting patients’ quality of life. A 61-year-old female patient presented to the clinic due to a swollen skin breakdown on the right inner ankle. She was diagnosed with diabetes at the age of 53 and developed her first diabetic foot ulcer at the age of 60. Laboratory results from this visit revealed a glycosylated hemoglobin level of 9.7%, a glycosylated albumin level of 26.8% and a fasting blood glucose level of 16.1 mmol/L. Ultrasonography of the lower limb arteries showed localized intimal-medial thickening with multiple sclerotic plaque formation on both lower limbs. For this patient, the multidisciplinary joint outpatient clinic for the diabetic foot was given systemic treatments such as blood glucose control, nerve nourishment, circulation improvement, lipid regulation and plaque fixation, while the diabetic foot care specialist gave an individualized wound treatment plan of cleansing, debridement and dressing coverage by evaluating the wound’s pH, infection grading and exudate traits, among other indicators. After 2 months of comprehensive treatment, the patient’s blood glucose control was stable and the ulcer healed. This case of recurrent ulcer rehabilitation provides new ideas for diabetic foot ulcer wound treatment and individualized wound treatment based on diabetic foot care led by experts holds promise as another effective means for healing diabetic foot ulcers.

Predictor-based constrained fixed-time sliding mode control of multi-UAV formation flight

In this work, a predictor-based fixed-time sliding mode control is designed to tackle the problem of achieving precise trajectory tracking control of multiple unmanned aerial vehicle formation flight. The proposed approach simultaneously addresses various practical requirements, such as optimality, constraints, fixed-time convergence, external interferences, and computational burden. Initially, using the Taylor series concept, we derive the predictive models for the fixed-time sliding surface and reaching law. Subsequently, we formulate a constrained performance index by integrating these predictions with the control input. Ultimately, the optimal control input is computed through solving the constrained quadratic optimization problem. An outstanding feature of this study is the theoretical guarantee of closed-loop fixed-time system stability in the presence of external disturbances and constraints. Furthermore, the comparative analysis with sliding mode predictive control law and fixed-time sliding mode control methods demonstrates that the proposed approach achieves a straightforward control method with improved performance and acceptable accuracy. Finally, an experimental test is conducted to demonstrate the algorithm's potential for hardware implementation by employing the Hardware-in-the-Loop test.

Automated real-time prediction of geological formation tops during drilling operations: an applied machine learning solution for the Norwegian Continental Shelf

Accurate prediction of geological formation tops is a crucial task for optimizing hydrocarbon exploration and production activities. This research investigates and conducts a comprehensive comparative analysis of several advanced machine learning approaches tailored for the critical application of geological formation top prediction within the complex Norwegian Continental Shelf (NCS) region. The study evaluates and benchmarks the performance of four prominent machine learning models: Support Vector Machine (SVM), K-Nearest Neighbors (KNN), Random Forest ensemble method, and Multi-Layer Perceptron (MLP) neural network. To facilitate a rigorous assessment, the models are extensively evaluated across two distinct datasets - a dedicated test dataset and a blind dataset independent for validation. The evaluation criteria revolve around quantifying the models' predictive accuracy in successfully classifying multiple geological formation top types. Additionally, the study employs the Density-Based Spatial Clustering of Applications with Noise (DBSCAN) algorithm as a baseline benchmarking technique to contextualize the relative performance of the machine learning models against a conventional clustering approach. Leveraging two model-agnostic feature importance analysis techniques - Permutation Feature Importance (PFI) and Shapley Additive exPlanations (SHAP), the investigation identifies and ranks the most influential input variables driving the predictive capabilities of the models. The comprehensive analysis unveils the MLP neural network model as the top-performing approach, achieving remarkable predictive accuracy with a perfect score of 0.99 on the blind validation dataset, surpassing the other machine learning techniques as well as the DBSCAN benchmark. However, the SVM model attains superior performance on the initial test dataset, with an accuracy of 0.99. Intriguingly, the PFI and SHAP analyses converge in consistently pinpointing depth (DEPT), revolution per minute (RPM), and Hook-load (HKLD) as the three most impactful parameters influencing model predictions across the different algorithms. These findings underscore the potential of sophisticated machine learning methodologies, particularly neural network-based models, to significantly enhance the accuracy of geological formation top prediction within the geologically complex NCS region. However, the study emphasizes the necessity for further extensive testing on larger datasets to validate the generalizability of the high performance observed. Overall, this research delivers an exhaustive comparative evaluation of state-of-the-art machine learning techniques, offering critical insights to guide the optimal selection, development, and real-world deployment of accurate and reliable predictive modeling strategies tailored for hydrocarbon exploration and reservoir characterization endeavors in the NCS.Graphical abstract

Highly Conductive Quasi‐1D Hexagonal Chalcogenide Perovskite Sr8Ti7S21 with Efficient Polysulfide Regulation in Lithium‐Sulfur Batteries

AbstractLithium‐sulfur batteries (LSBs) are regarded as one of the most promising candidates for next‐generation energy storage systems. However, the commercialization of LSBs is still hindered by several technical issues, including the notorious polysulfide migration from the cathode to the anode and the sluggish sulfur conversion kinetics. Herein, a quasi‐1D hexagonal chalcogenide perovskite, Sr8Ti7S21, is demonstrated as an efficient sulfur host able to overcome these limitations. Experimental results and density functional theory calculations show Sr8Ti7S21 to offer strong lithium polysulfides (LiPS) binding through multiple bond formation. Besides, Sr8Ti7S21 effectively facilitates the kinetics of the LiPS redox reaction. As a result, S@Sr8Ti7S21‐based cathodes exhibit excellent initial capacities up to 1315 mAh g−1 at 0.2C, impressive cycling stability with an average capacity decay rate of 0.08% per cycle over 400 cycles at 1C, and a high areal capacity of 6.58 mAh cm−2 under a high sulfur loading of 6.5 mg cm−2. This work reveals the potential capabilities and promising prospects of chalcogenide perovskites in advancing LSBs technology.

Evidence of evolution of the black hole mass function with redshift

Aims. We investigate the observed distribution of the joint primary mass, mass ratio, and redshift of astrophysical black holes using the gravitational wave events detected by the LIGO-Virgo-KAGRA collaboration and included in the third gravitational wave transient catalogue. Methods. We reconstructed this distribution using Bayesian non-parametric methods, which are data-driven models able to infer arbitrary probability densities under minimal mathematical assumptions. Results. We find evidence that both the primary mass and mass-ratio distribution evolve with redshift: our analysis shows the presence of two distinct subpopulations in the primary mass−redshift plane, with the lighter population, ≲20 M⊙, disappearing at higher redshifts, z &gt; 0.4. The mass-ratio distribution shows no support for symmetric binaries. Conclusions. The observed population of coalescing binary black holes evolves with look-back time, suggesting a trend in metallicity with redshift and/or the presence of multiple redshift-dependent formation channels.