bluuebunny/crossref_metadata_2025 huggingface dataset:
International Survey of High-Flow Nasal Therapy Use for Respiratory Failure in Adult Patients
Authors: Alnajada Asem , Blackwood Bronagh , Messer Ben , Pavlov Ivan , Shyamsundar Murali
Published: June 2023

(1) Background: High-flow nasal therapy (HFNT) has shown several benefits in addressing respiratory failure. However, the quality of evidence and the guidance for safe practice are lacking. This survey aimed to understand HFNT practice and the needs of the clinical community to support safe practice. (2) Method: A survey questionnaire was developed and distributed to relevant healthcare professionals through national networks in the UK, USA and Canada; responses were collected between October 2020 and April 2021. (3) Results: In the UK and Canada, HFNT was used in 95% of hospitals, with the highest use being in the emergency department. HNFT was widely used outside of a critical care setting. HFNT was mostly used to treat acute type 1 respiratory failure (98%), followed by acute type 2 respiratory failure and chronic respiratory failure. Guideline development was felt to be important (96%) and urgent (81%). Auditing of practice was lacking in 71% of hospitals. In the USA, HFNT was broadly similar to UK and Canadian practice. (4) Conclusions: The survey results reveal several key points: (a) HFNT is used in clinical conditions with limited evidence; (b) there is a lack of auditing; (c) it is used in wards that may not have the appropriate skill mix; and (d) there is a lack of guidance for HFNT use.
Differences in Heart Rate Variability and Baroreflex Sensitivity between Male and Female Athletes
Authors: Shafiq M. Abdullah , Ellingson Cody A. , Krätzig Gregory P. , Dorsch Kim D. , Neary J. Patrick , Singh Jyotpal
Published: June 2023

Heart rate variability (HRV), systolic blood pressure variability (BPV), and spontaneous baroreflex sensitivity (BRS) are indirect and approximate measures of autonomic regulation of the cardiovascular system. Studies have shown differences in HRV and BRS between males and females; however, no study has observed differences in BPV, HRV, or BRS between male and female athletes. One hundred males (age 21.2 ± 2.1 y; BMI 27.4 ± 4.5 kg/m2) and sixty-five females (age: 19.7 ± 1.6 y; BMI 22.7 ± 2.2 kg/m2) were assessed during the pre-season baseline. We collected resting beat-to-beat blood pressure and R-R intervals using finger photoplethysmography and a 3-lead electrocardiogram, respectively. Participants underwent a controlled slow breathing protocol (six breaths/minute: 5 s inhale, 5 s exhale) for 5 min. Spectral and linear analysis was conducted on blood pressure and ECG data. Regression curves were fitted to the blood pressure and R-R signals, with the slopes providing the BRS parameters. Male athletes had significantly (p < 0.05) lower mean heart rate, RR interval SD2/SD1, HRV % low-frequency, and higher BP high-frequency power during controlled respiration. No differences were found in any BRS parameters. HRV and BPV responses to a slow breathing protocol differed between male and female athletes; however, BRS responses did not.
The Outcome of Molecularly Targeted Therapy after Surgical Treatment of Spinal Metastasis
Authors: Sugita Shurei , Ogiso Sawako , Fujiwara Masanori , Morita Euan , Koyama Takuma , Hozumi Takahiro
Published: June 2023

The aim of this study was to investigate outcomes of molecularly targeted therapy after surgical treatment of spinal metastasis. Participants comprised 164 patients who underwent surgical treatment of spinal metastasis, divided according to whether molecularly targeted therapy was performed. We compared survival, local recurrence of metastasis detected by imaging, the disease-free interval, relapses of neurological deterioration, and the ability to walk between groups. Molecularly targeted drugs were administered to 39 patients after surgery (TT group) and were not administered to 125 patients (non-TT group). Median survival was significantly longer in the TT group (1027 days) than in the non-TT group (439 days, p < 0.01). Local recurrence occurred in 25 patients in the non-TT group and 10 patients in the TT group. The disease-free interval did not differ between groups. Neurological deterioration was observed in three patients in the non-TT group and no patients in the TT group. The ability to walk was preserved in 97.6% of patients in the TT group and 88% of patients in the non-TT group (p = 0.12). In conclusion, molecularly targeted drugs improve survival in patients with spinal metastasis but do not alter local control of metastatic tumors.
Changing Epidemiological Patterns of Infection and Mortality Due to Hepatitis C Virus in Poland
Authors: Genowska Agnieszka , Zarębska-Michaluk Dorota , Strukcinskiene Birute , Razbadauskas Arturas , Moniuszko-Malinowska Anna , Jurgaitis Jonas , Flisiak Robert
Published: June 2023

Introduction: Limited information is available on trends in hepatitis C virus (HCV) infection, particularly in Central Europe. To address this knowledge gap, we analyzed HCV epidemiology in Poland, considering socio-demographic characteristics, changing patterns over time, and the impact of the COVID-19 pandemic. Material and Methods: We examined HCV cases (diagnosis and deaths) reported by national registries and used joinpoint analysis to estimate time trajectories. Results: Between 2009 and 2021, there were changes in the trends of HCV, shifting from positive to negative in Poland. Among men, there was a significant increase initially in diagnosis rate of HCV in rural areas (annual percent change, APC2009–2016 +11.50%) and urban areas (APC2009–2016 +11.44%) by 2016. In subsequent years until 2019, the trend changed direction, but the reduction was weak (Ptrend > 0.05) in rural areas (−8.66%) and urban areas (−13.63%). During the COVID-19 pandemic, the diagnosis rate of HCV dramatically decreased in rural areas (APC2019–2021 −41.47%) and urban areas (APC2019–2021 −40.88%). Among women, changes in the diagnosis rate of HCV were less pronounced. In rural areas, there was a significant increase (APC2009–2015 +20.53%) followed by no significant change, whereas changes occurred later in urban areas (APC2017–2021 −33.58%). Trend changes in total mortality due to HCV were mainly among men, with a significant decrease in rural (−17.17%) and urban (−21.55%) areas from 2014/2015. Conclusions: The COVID-19 pandemic reduced HCV diagnosis rates in Poland, especially for diagnosed cases. However, further monitoring of HCV trends is necessary, along with national screening programs and improved linkage to care.
Imaging of Gastrointestinal Tract Ailments
Authors: Sun Boyang , Liu Jingang , Li Silu , Lovell Jonathan F. , Zhang Yumiao
Published: June 2023

Gastrointestinal (GI) disorders comprise a diverse range of conditions that can significantly reduce the quality of life and can even be life-threatening in serious cases. The development of accurate and rapid detection approaches is of essential importance for early diagnosis and timely management of GI diseases. This review mainly focuses on the imaging of several representative gastrointestinal ailments, such as inflammatory bowel disease, tumors, appendicitis, Meckel’s diverticulum, and others. Various imaging modalities commonly used for the gastrointestinal tract, including magnetic resonance imaging (MRI), positron emission tomography (PET) and single photon emission computed tomography (SPECT), and photoacoustic tomography (PAT) and multimodal imaging with mode overlap are summarized. These achievements in single and multimodal imaging provide useful guidance for improved diagnosis, staging, and treatment of the corresponding gastrointestinal diseases. The review evaluates the strengths and weaknesses of different imaging techniques and summarizes the development of imaging techniques used for diagnosing gastrointestinal ailments.
The Impact of Item Difficulty on Judgment of Confidence—A Cross-Level Moderated Mediation Model
Authors: Zhou Yuke , Jia Ning
Published: June 2023

The factors that influence metacognitive judgments often appear in combination, rather than in isolation. The multi-cue utilization model proposes that individuals often make use of multiple cues when making judgments. Previous studies have focused on the integration of intrinsic and extrinsic cues, while the current investigation examines the integration and influence of intrinsic cues and mnemonic cues. Judgment of confidence is a common form of metacognitive judgment. In this study, 37 college students completed Raven’s Progressive Matrices and made judgments of confidence. We used the cross-level moderated mediation model to explore the impact of item difficulty on confidence judgments. Our results indicated that item difficulty negatively predicts the level of confidence. Item difficulty has an impact on the confidence evaluation by altering the processing fluency of intermediate variables. The joint effect of intrinsic cue item difficulty and mnemonic cue processing fluency influences confidence judgments. Additionally, we found that intelligence moderates the effect of difficulty on processing fluency across levels. Specifically, individuals with higher intelligence exhibited lower fluency on difficult tasks and higher fluency on simple tasks than individuals with lower intelligence. These findings expand on the multi-cue utilization model and integrate the influence mechanism of intrinsic and mnemonic cues on confidence judgments. Finally, we propose and verify a cross-level moderated mediation model that explains how item difficulty affects confidence judgments.
Assessment of Plasma Deposition Parameters for DED Additive Manufacturing of AA2319
Authors: Rodríguez-González Paula , Neubauer Erich , Ariza Enrique , Bolzoni Leandro , Gordo Elena , Ruiz-Navas Elisa María
Published: June 2023

Arc-directed energy deposition using wire as feedstock is establishing itself as a 3D printing method capable of obtaining additively manufactured large structures. Contrasting results are reported in the literature about the effect of the deposition parameters on the quality of the deposited tracks, as it is highly dependent on the relationship and intercorrelations between the individual input parameters, which are generally deposition-technique-dependent. This study comprehensively analysed the effect of several deposition parameters and clarified their interactions in plasma metal deposition of Al alloys. It was found that, although no straightforward correlation between the individual input parameters investigated and the measured output deposition track’s quality aspects existed, the input current had the greatest effect, followed by the wire feed speed and its interaction with the input current. Moreover, the greatest effect of changing the shielding gas atmosphere, including the gas mixture, flow rate and plasma flow, was on the penetration depth, and fine-tuning the frequency/balance ratio and the preheating of the deposition substrates reduced the amount of porosity. This study demonstrates that well-deposited multi-layer walls made out of Al alloys can successfully be achieved via plasma metal deposition.
Multi-Faceted Analysis of Airborne Noise Impact in the Port of Split (II)
Authors: Jelić Mrčelić Gorana , Vukić Luka , Jambrošić Kristian
Published: June 2023

Given the increasing number of citizen complaints about port noise and the lack of relevant studies assessing resident exposure, the effects of port noise are gaining increasing public attention. It is especially significant in ports near residential areas, where excessive noise emissions can seriously impact the urban environment. This paper aimed to investigate the perceptions and attitudes of the population living near the cargo terminals in the Port of Split regarding the impact of port noise in the urban area, focusing on their health and standards of living. The research methodology included a questionnaire distributed in the areas where the residents are most affected by noise. In addition to conventional descriptive survey analysis, the authors used regression analysis and two-way ANOVA with the Tukey post hoc test as a parametric data analysis tool. The survey results showed the harmful effects of port noise on most set parameters, and perceived noise intensity for three different times of the day caused a high level of concern for the urban environment. In addition, the regression analysis results showed a weak and reverse dependency between the distance of the selected residences from the noise sources and the perceived noise intensity. These findings support the validity of the respondents’ perceptions and the credibility of the obtained results. The application of parametric data analysis revealed a lack of formal knowledge of residents about the effects of noise and a strong differentiation between groups based on the variables that determine the level of education of residents and their assessments of the noise intensity of the cargo terminal. However, the subjective impressions and the psycho-physical and emotional states of the residents need also to be included in the validation of the results. The obtained results will facilitate the adoption of noise management policies and implementation of noise abatement programs in the Port of Split.
A Data Valuation Model to Estimate the Investment Value of Platform Companies: Based on Discounted Cash Flow
Authors: Cheong Hyongmook , Kim Boyoung , Vaquero Ivan Ureta
Published: June 2023

As both investment attraction and mergers and acquisitions targeting information technology and platform companies are becoming more important in the digital-centric economic environment, interest in valuing corporate data assets is increasing. Accordingly, among the income approaches used in business valuation, this study presents a data valuation model based on discounted cash flow. This model is expected to be useful for corporate investment decision-making. The assumptions used in this study for the estimation of data income include intangible asset value, exclude net asset value, and data attribution is centered on technology, human resources, and market factors. In particular, data attribution accounts comprise ordinary data research and development, data labor costs, and data advertising expenses. Data costs were divided into those incurred during collection, storage, curation, analysis, and utilization. Financial statements and related data from a real estate information platform operator over three years were collected and used to simulate the data valuation model. The simulation reveals that the operator possesses KRW 472.6 billion in data assets. Ultimately, the data valuation model developed in this study can contribute to strengthening platform operators’ investment attraction, guaranteeing financial sustainability, and transparency and data assetization.
Milestones and Current Dilemmas: Evaluation of Sentencing Standardization for Illegal Possession of Drugs in China
Authors: Wu Jia , Xia Yang , Song Apei
Published: June 2023

It has been more than ten years since the nationwide sentencing standardization reform was implemented in China to solve the widespread problem of uneven sentencing in criminal justice. A statistical analysis of 1595 written judgments of illegal possession of drugs showed that the reform of sentencing for the standardization amount-based crimes has achieved remarkable results, and judges’ discretion has been highly normative and consistent. Under the same criminal circumstances, the degree of consistency between the amount involved in the crime and imprisonment has significantly increased, which is more in line with the standards of formal justice. However, the effect of the sentencing standardization reform declined as the amount involved in the crime increased. This exposes the shortcomings of the standardized sentencing model when considering multiple crimes; these include confusion between the amount and circumstances of a crime, the imbalance between crime and punishment, and the application of discretionary circumstances in sentencing depending on the amount involved in the crime. Therefore, it is necessary to attach more importance to the evaluation of the legitimacy of the sentencing range established by criminal law in subsequent sentencing reforms and to further refine and perfect the standardized sentencing mode, with a shift from formal justice to justice in form and substance.
Neurohumoral Markers of Cardiac Autonomic Denervation after Surgical Ablation of Long-Standing Persistent Atrial Fibrillation
Authors: Evtushenko Alexey , Evtushenko Vladimir , Gusakova Anna , Suslova Tatiana , Varlamova Yulia , Zavadovskiy Konstantin , Lebedev Denis , Kutikhin Anton , Pavlyukova Elena , Mamchur Sergey
Published: June 2023

Although the autonomic nervous system has an evident impact on cardiac electrophysiology and radiofrequency ablation (RFA) is the conventional technique for treating persistent atrial fibrillation, the specific effects of RFA have been insufficiently studied to date. Here, we investigated whether RFA affects neurohumoral transmitter levels and myocardial 123I-metaiodobenzylguanidine (123I-MIBG) uptake. To perform this task, we compared two groups of patients with acquired valvular heart disease: patients who had undergone surgical AF ablation and patients with sinus rhythm. The decrease in norepinephrine (NE) level in the coronary sinus had a direct association with the heart-to-mediastinum ratio (p = 0.02) and a negative correlation with 123I-MIBG uptake defects (p = 0.01). The NE level decreased significantly after the main surgery, both in patients with AF (p = 0.0098) and sinus rhythm (p = 0.0039). Furthermore, the intraoperative difference between the norepinephrine levels in the ascending aorta and coronary sinus (ΔNE) of –400 pg/mL was determined as a cut-off value to evaluate RFA efficacy, as denervation failed in all patients with ΔNE < –400 pg/mL. Hence, ΔNE can be utilized to predict the efficacy of the “MAZE-IV” procedure and to assess the risk of AF recurrence after RFA.
Predictors of Pulmonary Hypertension and Right Ventricular Dysfunction in Patients with Hypersensitivity Pneumonitis
Authors: Trushenko Natalia V. , Suvorova Olga A. , Nekludova Galina V. , Levina Iuliia A. , Chikina Svetlana Y. , Nikolenko Alexandra M. , Tsareva Natalia A. , Volkov Alexandr V. , Yaroshetskiy Andrey I. , Merzhoeva Zamira M. , Nuralieva Galiya S. , Avdeev Sergey N.
Published: June 2023

Background: Hypersensitivity pneumonitis (HP) is an interstitial lung disease (ILD) that occurs in susceptible individuals in response to various inhaled antigens. The fibrotic phenotype of HP is characterized by disease progression and can lead to pulmonary hypertension (PH). The aim of this study was to estimate the prevalence of PH and to identify predictors of PH in patients with chronic HP. Methods: We conducted an observational longitudinal study that included 85 patients with an established diagnosis of HP. Clinical examination, quality of life questionnaires, high-resolution computed tomography (HRCT) of the chest, arterial blood gases analyses, six-minute walking test (6-MWT), pulmonary function tests, and echocardiography were performed. Results: Patients were divided into groups with fibrotic (71.8%) and nonfibrotic phenotype (28.2%). PH was detected in 41 (48.2%) patients. Patients with PH had the predominant fibrotic phenotype of HP, were older, more symptomatic, and had a higher FVC/DLco ratio. The most significant predictors of PH were CT signs of fibrosis, finger clubbing, FVC/DLco, decreased distance, and SpO2 at the end of 6-MWT, as well as the presence of cardiovascular diseases. Conclusions: PH is a common condition in patients with chronic HP, especially with the fibrotic phenotype. Early detection of the PH predictors is necessary for the timely diagnosis of this complication of HP.
Targeting Ion Channels and Purkinje Neuron Intrinsic Membrane Excitability as a Therapeutic Strategy for Cerebellar Ataxia
Authors: Huang Haoran , Shakkottai Vikram G.
Published: June 2023

In degenerative neurological disorders such as Parkinson’s disease, a convergence of widely varying insults results in a loss of dopaminergic neurons and, thus, the motor symptoms of the disease. Dopamine replacement therapy with agents such as levodopa is a mainstay of therapy. Cerebellar ataxias, a heterogeneous group of currently untreatable conditions, have not been identified to have a shared physiology that is a target of therapy. In this review, we propose that perturbations in cerebellar Purkinje neuron intrinsic membrane excitability, a result of ion channel dysregulation, is a common pathophysiologic mechanism that drives motor impairment and vulnerability to degeneration in cerebellar ataxias of widely differing genetic etiologies. We further propose that treatments aimed at restoring Purkinje neuron intrinsic membrane excitability have the potential to be a shared therapy in cerebellar ataxia akin to levodopa for Parkinson’s disease.
Bearing Non-Uniform Loading Condition Monitoring Based on Dual-Channel Fusion Improved DenseNet Network
Authors: Zhang Yanfei , Liu Yang , Wang Lijie , Li Dongya , Zhang Wenxue , Kong Lingfei
Published: June 2023

Misalignment or unbalanced loading of machine tool spindle bearings often results in skewed bearing operation, which makes the spindle more susceptible to failure. In addition, due to the weak impact signal of the bearing in skewed operation, a single feature information cannot accurately characterize the operation status of the bearing. To address the above problems, this paper proposes a method to monitor the uneven running state of bearing load based on a dual-channel fusion improved dense connection (DenseNet) network. First, the original signal is pre-processed by overlapping sampling method, and the dual-channel experimental data are obtained by frequency-domain and time-frequency-domain algorithms; then the processed data are input into the improved 1D-DenseNet and 2D-DenseNet models respectively for feature extraction; then the frequency-domain and time-frequency-domain features are fused by concat splicing operation, and the output belongs to each category The probability distribution is used to characterize the operating state of the bearings. Finally, the validity of the algorithm model is verified by using the Case Western Reserve University public rolling bearing data set, and an experimental bench is designed and built for experimental verification of the uneven bearing load operation. The comparative analysis of the experimental results in this paper shows that the algorithm can extract the features of the input signal more comprehensively and finally achieve 100% recognition accuracy.
Rotordynamic Analysis and Operating Test of an Externally Pressurized Gas Bearing Turbo Expander for Cryogenic Applications
Authors: Lee Donghyun , Lim Hyungsoo , Kim Byungock , Jeon Byungchan , Park Junyoung
Published: June 2023

This study designed an externally pressurized bearing and analyzed the rotordynamics of a turbo expander for a hydrogen liquefaction plant. The turbo expander, comprising a turbine and compressor wheel assembled to a shaft, lowered the temperature of the helium refrigerant. Its rated speed was 75,000 rpm, and an externally pressurized gas bearing was selected to support the rotor. Pressurized helium was used as the lubricant for the bearing operation. To design the rotor–bearing system, we conducted a bearing performance analysis and rotordynamic characteristic prediction using the developed numerical model. We calculated the bearing stiffness and flow rate of the bearing gas for various feed parameters and selected the appropriate orifice diameter for maximum stiffness. The predicted Campbell diagram showed that the system had a sufficient separation margin with the critical speed, and the predicted critical speed correlated well with the nonlinear orbit simulation. A successful operation was achieved with the manufactured turbo expander within the rated speed. The shaft vibration was monitored during the operation test, and the test results revealed two critical speeds below the rated speed, as predicted by the analytical model. In addition, the shaft vibration was maintained at <3 μm.
Experimental Study on the Strength and Hydration Products of Cement Mortar with Hybrid Recycled Powders Based Industrial-Construction Residue Cement Stabilization of Crushed Aggregate
Authors: Deng Miaoyi , Xie Xiangbing , Zhuo Jingbo , He Yahui , Wang Kaiwei
Published: June 2023

The strength-formation mechanism for industrial-construction residue cement stabilization of crushed aggregate (IRCSCA) is not clear. To expand the application range for recycled micro-powders in road engineering, the dosages of eco-friendly hybrid recycled powders (HRPs) with different proportions of RBP and RCP affecting the strengths of cement-fly ash mortar at different ages, and the strength-formation mechanism, were studied with X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the early strength of the mortar was 2.62 times higher than that of the reference specimen when a 3/2 mass ratio of brick powder and concrete powder was mixed to form the HRP and replace some of the cement. With increasing HRP content substituted for fly ash, the strength of the cement mortar first increased and then decreased. When the HRP content was 35%, the compressive strength of the mortar was 1.56 times higher than that of the reference specimen, and the flexural strength was 1.51 times higher; XRD and SEM studies of the hydrated cement mixed with HRP showed that the amount of CH in the cement paste was reduced by the pozzolanic reaction of HRP at later hydration ages, and it was very useful in improving the compactness of the mortar. The XRD spectrum of the cement paste made with HRP indicated that the CH crystal plane orientation index R, with a diffraction angle peak of approximately 34.0, was consistent with the cement slurry strength evolution law, and this research provides a reference for the application of HRP to produce IRCSCA.
Microstructural, Biomechanical, and In Vitro Studies of Ti-Nb-Zr Alloys Fabricated by Powder Metallurgy
Authors: Karakurt Eyyup Murat , Cetin Yuksel , Incesu Alper , Demirtas Huseyin , Kaya Mehmet , Yildizhan Yasemin , Tosun Merve , Huang Yan
Published: June 2023

This study investigated the microstructures, mechanical performances, corrosion resistances, and in vitro studies of porous Ti-xNb-10Zr (x: 10 and 20; at. %) alloys. The alloys were fabricated by powder metallurgy with two categories of porosities, i.e., 21–25% and 50–56%, respectively. The space holder technique was employed to generate the high porosities. Microstructural analysis was performed by using various methods including scanning electron microscopy, energy dispersive spectroscopy, electron backscatter diffraction, and x-ray diffraction. Corrosion resistance was assessed via electrochemical polarisation tests, while mechanical behavior was determined by uniaxial compressive tests. In vitro studies, such as cell viability and proliferation, adhesion potential, and genotoxicity, were examined by performing an MTT assay, fibronectin adsorption, and plasmid-DNA interaction assay. Experimental results showed that the alloys had a dual-phase microstructure composed of finely dispersed acicular hcp α-Ti needles in the bcc β-Ti matrix. The ultimate compressive strength ranged from 1019 MPa to 767 MPa for alloys with 21–25% porosities and from 173 MPa to 78 MPa for alloys with 50–56% porosities. Noted that adding a space holder agent played a more critical role in the mechanical behaviors of the alloys compared to adding niobium. The pores were largely open and exhibited irregular shapes, with uniform size distribution, allowing for cell ingrowth. Histological analysis showed that the alloys studied met the biocompatibility criteria required for orthopaedic biomaterial use.
Polarization-Multiplexed High-Throughput AOTF-Based Spectral Imaging System
Authors: Zhang Hao , Zhao Huijie , Guo Qi , Xu Dong , Teng Wenjie
Published: June 2023

Spectral imaging detection using acousto-optical tunable filters (AOTFs) faces a significant challenge of low throughput due to the traditional design that only receives a single polarization light. To overcome this issue, we propose a novel polarization multiplexing design and eliminate the need for crossed polarizers in the system. Our design allows for simultaneous collection of ±1 order light from the AOTF device, resulting in a more than two-fold increase in system throughput. Our analysis and experimental results validate the effectiveness of our design in improving system throughput and enhancing the imaging signal-to-noise ratio (SNR) by approximately 8 dB. In addition, AOTF devices used in polarization multiplexing applications require optimized crystal geometry parameter design that does not follow the parallel tangent principle. This paper proposes an optimization strategy for arbitrary AOTF devices which can achieve similar spectral effects. The implications of this work are significant for target detection applications.
Edgewise Compression and Three-Point Bending Analyses of Repaired Composite Sandwich Panels
Authors: Rocha Ricardo J. B. , de Moura Marcelo F. S. F. , Moreira Raul D. F.
Published: June 2023

In this work, the fracture behaviour of repaired honeycomb/carbon–epoxy sandwich panels under edgewise compression and three-point bending loading was analysed. Assuming the occurrence of damage resulting from a complete perforation leading to an open hole, the followed repair strategy consists of plug filling the core hole and considering two scarf patches with an angle of 10° in order to repair the damaged skins. Experimental tests were performed on undamaged and repaired situations in order to address the alteration in the failure modes and assess the repair efficiency. It was observed that repair recovers a large part of the mechanical properties of the corresponding undamaged case. Additionally, a three-dimensional finite element analysis incorporating a mixed-mode I + II + III cohesive zone model was performed for the repaired cases. Cohesive elements were considered in the several critical regions prone to damage development. The failure modes and the resultant load–displacement curves obtained numerically were compared with the experimental ones. It was concluded that the numerical model is suitable for estimating the fracture behaviour of sandwich panel repairs.
The Adsorption Performance of Porous Activated Carbons Prepared from Iron (II) Precursors Precipitated on the Porous Carbon Matrix Thermolysis
Authors: Kalenskii Alexander , Ivanov Aleksey , Sevostyanov Dmitriy , Zvekov Alexander , Krechetov Alexander
Published: June 2023

The creation of new compounds featuring high adsorption and catalytic performance with magnetic properties of the material is one of the important fields of magnetochemistry. The typical synthetic schemes of magnetic carbonaceous adsorbents are rather complicated due to the use of inert atmosphere and difficult wet methods of magnetite precipitation. The arising experimental issues prevent industrial production of magnetically activated carbons. In order to overcome these obstacles, we suggested a novel approach to porous carbons: magnetite composite synthesis based on iron (II) salt precipitation on porous carbon and subsequent thermolysis. We facilitated the process at the stage of the material washing. The synthetic route used is simple and can be applied industrially. The present paper is focused on the adsorption performance of a product prepared from commercial activated carbons BAU-A and AG-3. The porous structure was studied with low-temperature nitrogen adsorption that revealed surface area decreased by 26% in the case of BAU-A and 40% in the case of AG-3 with an increase in mesopore volume. Phenol and nitrobenzene adsorption from water solution was tested with magnetic carbon prepared from BAU-A. The adsorption isotherms obtained are described well using the Langmuir model. The limiting adsorption value in the case of magnetic porous carbon is lower than in the case of pristine carbon. The relative decrease in limiting adsorption value is close to the relative decrease in the specific surface area. The adsorption constant remains the same, showing that adsorption centers of phenol and nitrobenzene are the same for porous magnetic carbon and its activated carbon precursor. Thus, we showed in the present study that the magnetically activated carbons we developed almost retain the adsorption performance of their activated carbon precursors.
Predictors of Outcome in Patients with Pulmonary Hypertension Undergoing Mitral and Tricuspid Valve Surgery
Authors: Kew Ee Phui , Caruso Vincenzo , Grapsa Julia , Bosco Paolo , Lucchese Gianluca
Published: June 2023

Background and Objectives: Pulmonary hypertension (PH) secondary to left-sided valvular heart disease is associated with poor cardiac surgical outcome compared with patients without PH. Our objective was to investigate the prognostic factors of surgical outcome in patients with PH undergoing mitral valve (MV) and tricuspid valve (TV) surgery, in order to risk stratify their management. Materials and Methods: This is a retrospective observational study on patients with PH who underwent MV and TV surgery from 2011 to 2019. The primary outcome was all-cause mortality. The secondary outcomes were post-op respiratory and renal complications, length of intensive care unit stay and length of hospital stay. Results: Seventy-six patients were included in this study. The all-cause mortality was 13% (n = 10), with mean survival of 92.6 months. Among the patients, 9.2% (n = 7) had post-op renal failure requiring renal replacement therapy and 6.6% (n = 5) had post-op respiratory failure requiring intubation. Univariate analysis demonstrated that pre-operative left ventricular ejection fraction (LVEF), peak systolic tissue velocity at the tricuspid annulus (S’) and etiology of MV disease were associated with respiratory and renal failure. Tricuspid annular plane systolic excursion (TAPSE) was associated with respiratory failure only. S’, type of operation, LVEF, urgency of surgery, and etiology of MV disease were found to be predictive of mortality. After excluding redo mitral surgery, all statistically significant findings remain unchanged, with the addition of right ventricular (RV) size being associated with respiratory failure. In the subgroup analysis of routine cases (n = 56), patients with primary mitral regurgitation who underwent mitral valve repair had better survival outcome. Conclusions: Urgency of surgery, etiology of MV disease, type of operation (replacement or repair), S’ and pre-op LVEF are prognostic indicators in this small cohort of patients with PH undergoing MV and TV surgery. A larger prospective study is warranted to validate our findings.
Visual Impairment in Hemodialyzed Patients—An IVIS Study
Authors: Sułkowski Leszek , Rubinkiewicz Mateusz , Matyja Andrzej , Matyja Maciej
Published: June 2023

Background and Objectives: The growing and aging population of hemodialysis patients has become increasingly disabled, with more complex comorbidities, and are older upon initiating dialysis. Visual impairment can adversely affect their quality of life and life satisfaction. Treatment evaluation should not only consider remission of the disease, but also the improvement of quality of life and life satisfaction. This is a single-center cross-sectional study. It was designed to evaluate visual impairment in hemodialyzed patients, its correlation with quality of life and life satisfaction, and its relationship to clinical outcomes in hemodialyzed patients. Materials and Methods: Seventy patients with chronic kidney disease undergoing hemodialysis and aged 18 years or older were recruited from a single Dialysis Unit. The Impact of Visual Impairment Scale (IVIS), WHOQOL-BREF, and Cantril Ladder questionnaires were utilized to assess both sociodemographic and clinical variables. Results: It was found that, among all assessed variables (i.e., sex, marital status, level of education, months on hemodialysis, history of kidney transplantation, Kt/V, URR, and UF), only age and central venous catheter placement were positively correlated with IVIS scores, while arteriovenous fistula and willingness to become a kidney transplant recipient were negatively correlated. Furthermore, a comparison between patients with moderate and severe visual impairment yielded supplemental data indicating that individuals whose dialysis access was through a dialysis catheter and those ineligible or unwilling to undergo transplantation suffered more often from severe visual impairment. This finding may be attributed to age. Conclusions: Older patients were predominantly observed to experience visual impairment. Patients intending to receive a kidney transplant and whose dialysis access was through an arteriovenous fistula were less prone to visual impairment, compared to those who may be ineligible or unwilling to receive transplantation and those with hemodialysis catheters. This phenomenon can be attributed to age-related distinctions in patients’ suitability for specific dialysis access and transplantation. Those reporting visual impairment gave lower ratings in all four domains of their quality of life (comprising physical health, psychological health, social relationships, and environment) and in both present and anticipated five-year life satisfaction. More severe visual impairment was related to an additional reduction in physical health, social relationship, and environment domains, and in life satisfaction.
Microstructure and Mechanical Properties of TC4 Titanium Alloy at the Temperature of 77K
Authors: Zhao Yuetao , Li Xuewen , Fang Wenbin
Published: June 2023

Titanium alloy has the advantages of low thermal conductivity, a small expansion coefficient and being non-magnetic, making it an ideal low-temperature structural material. In this paper, the typical TC4 titanium alloy in industrial titanium alloy is selected as the research object. The microstructure deformation law and mechanical behavior of TC4 titanium alloy at liquid nitrogen temperature are mainly investigated, and compared with the microstructure and properties at room temperature. The macroscopic and microscopic deformation mechanism of the simultaneous increase in elongation and hardening index of titanium alloy at low temperature is revealed, which provides a basic basis for the low-temperature deformation mechanism and strengthening and toughening design of titanium alloy. Based on the uniaxial tensile tests at room temperature (298 K) and low temperature (77 K), the effects of low temperature on the yield strength, elongation, tensile strength and work hardening curve of titanium alloy were compared and analyzed. The strength/plasticity synergistic improvement of TC4 titanium alloy under low-temperature deformation was found. At low temperature, the yield strength, tensile strength and elongation of TC4 titanium alloy are improved compared with room temperature. The tensile strength increases from 847.93 MPa at 298 K to 1318.70 MPa at 77 K, and the elongation increases from 21.8% at 298 K to 24.9% at 77 K. The grain morphology, grain orientation, dislocation density and fracture morphology of titanium alloy under room temperature and low-temperature tensile conditions were studied by SEM and EBSD. The results of fracture morphology characterization at room temperature and low temperature show that TC4 titanium alloy exhibits ductile fracture characteristics and a large number of dimples are formed on the fracture surface. The dimple depth at low temperature is shallower than that at room temperature and the overall surface is more flat. Compared with room temperature deformation, the deformation process of TC4 titanium alloy in a low-temperature environment produces stronger dislocation pile-up and forms a large number of twins, but the grain rotation is more significant, which effectively alleviates the stress concentration and delays the initiation and propagation of cracks at grain boundaries.
Precision Motion Control of a Piezoelectric Actuator via a Modified Preisach Hysteresis Model and Two-Degree-of-Freedom H-Infinity Robust Control
Authors: Baziyad Ayad G. , Ahmad Irfan , Salamah Yasser Bin
Published: June 2023

The nonlinear hysteresis phenomenon can occur in piezoelectric-driven nanopositioning systems and can lead to reduced positioning accuracy or result in a serious deterioration of motion control. The Preisach method is widely used for hysteresis modeling; however, for the modeling of rate-dependent hysteresis, where the output displacement of the piezoelectric actuator depends on the amplitude and frequency of the input reference signal, the desired accuracy cannot be achieved with the classical Preisach method. In this paper, the Preisach model is improved using least-squares support vector machines (LSSVMs) to deal with the rate-dependent properties. The control part is then designed and consists of an inverse Preisach model to compensate for the hysteresis nonlinearity and a two-degree-of-freedom (2-DOF) H-infinity feedback controller to enhance the overall tracking performance with robustness. The main idea of the proposed 2-DOF H-infinity feedback controller is to find two optimal controllers that properly shape the closed-loop sensitivity functions by imposing some templates in terms of weighting functions in order to achieve the desired tracking performance with robustness. The achieved results with the suggested control strategy show that both hysteresis modeling accuracy and tracking performance are significantly improved with average root-mean-square error (RMSE) values of 0.0107 μm and 0.0212 μm, respectively. In addition, the suggested methodology can achieve better performance than comparative methods in terms of generalization and precision.
Navigation and Control of Motion Modes with Soft Microrobots at Low Reynolds Numbers
Authors: Kararsiz Gokhan , Duygu Yasin Cagatay , Wang Zhengguang , Rogowski Louis William , Park Sung Jea , Kim Min Jun
Published: June 2023

This study investigates the motion characteristics of soft alginate microrobots in complex fluidic environments utilizing wireless magnetic fields for actuation. The aim is to explore the diverse motion modes that arise due to shear forces in viscoelastic fluids by employing snowman-shaped microrobots. Polyacrylamide (PAA), a water-soluble polymer, is used to create a dynamic environment with non-Newtonian fluid properties. Microrobots are fabricated via an extrusion-based microcentrifugal droplet method, successfully demonstrating the feasibility of both wiggling and tumbling motions. Specifically, the wiggling motion primarily results from the interplay between the viscoelastic fluid environment and the microrobots’ non-uniform magnetization. Furthermore, it is discovered that the viscoelasticity properties of the fluid influence the motion behavior of the microrobots, leading to non-uniform behavior in complex environments for microrobot swarms. Through velocity analysis, valuable insights into the relationship between applied magnetic fields and motion characteristics are obtained, facilitating a more realistic understanding of surface locomotion for targeted drug delivery purposes while accounting for swarm dynamics and non-uniform behavior.
Uranium Geochemistry of Italian Travertines and Calcareous Tufas: Exploring the Relationship between Carbonate Deposition, Groundwater Circulation and Subsurface Geology
Authors: Giustini Francesca , Brilli Mauro
Published: June 2023

A database consisting of 163 data on the uranium content and 234U/238U initial activity ratio of 15 Italian travertine and calcareous tufa sites was created using data from the relevant literature. Using a graphical method, data were interpreted considering the U geochemistry in natural environments as well as the geological, hydrogeological and hydrogeochemical settings of each site. The U content and 234U/238U initial activity ratio in travertine and tufa appear to be affected by different factors, such as the availability of U in the aquifer rocks, the redox state of the waters, and the alpha-active radionuclide recoil phenomenon. The data allow the identification of four groups of travertines/tufas: (i) those precipitated from circulating groundwater, with a short/fast flow path, in volcanic rocks with a high radionuclide content; (ii) those precipitated from circulating groundwater, with a long, deep flow path in carbonate/evaporite formations with a relatively low radionuclide content; and (iii) those precipitated from cold waters associated with riverine systems, which are characterized by oxidizing conditions and fed by high-discharge springs recharged by carbonate aquifers. The fourth group represents the intermediate situations frequently occurring due to the mixing of waters from different aquifers. The results suggest an interpretative model that might contribute to the paleo-environmental reconstruction of fossil travertine and calcareous tufa depositing systems.
Therapeutic Fasting in Reducing Chemotherapy Side Effects in Cancer Patients: A Systematic Review and Meta-Analysis
Authors: Ferro Yvelise , Maurotti Samantha , Tarsitano Maria Grazia , Lodari Oscar , Pujia Roberta , Mazza Elisa , Lascala Lidia , Russo Raffaella , Pujia Arturo , Montalcini Tiziana
Published: June 2023

The aim of this study was to assess the available evidence regarding the effect of a variety of fasting-like regimens on preventing chemotherapy-related side effects. PubMed, Scopus and Embase were used to select the studies for this review, which concluded on 24 November 2022. All types of clinical trials and case series reporting chemotherapy toxicity associated with fasting regimens and any comparison were considered. A total of 283 records were identified, of which 274 were excluded, leaving only nine studies that met the inclusion criteria. Five of these trials were randomized. Overall, moderate to high-quality evidence showed that several fasting regimens did not provide benefits compared to a conventional diet or other comparators in reducing the risk of adverse events. The overall pooled estimate for a variety of fasting regime when compared to non-fasting, indicated no significant difference in the side effects (RR = 1.10; 95% CI: 0.77–1.59; I2 = 10%, p = 0.60), including neutropenia alone (RR = 1.33; 95% CI: 0.90–1.97; I2 = 0%, p = 0.15). A sensitivity analysis confirmed these results. Based on our systematic review and meta-analysis, there is currently no evidence supporting the superiority of therapeutic fasting over non-fasting in preventing chemotherapy toxicity. The development of cancer treatment that do not entail toxicities remains imperative.
Young Artistic Gymnasts Drink Ad Libitum Only Half of Their Fluid Lost during Training, but More Fluid Intake Does Not Influence Performance
Authors: Chryssanthopoulos Costas , Dallas Georgios , Arnaoutis Giannis , Ragkousi Eirini Charikleia , Kapodistria Georgia , Lambropoulos Ioannis , Papassotiriou Ionas , Philippou Anastassios , Maridaki Maria , Theos Apostolos
Published: June 2023

To examine the effect of the fluid balance on and performance in young artistic gymnasts during training under ad libitum and prescribed fluid intake conditions, eleven males (12.3 ± 2.6 years, mean ± SD) performed two 3 h identical training sessions. Participants ingested, in a random order, water equivalent to either 50% (LV) or 150% (HV) of their fluid loss. After the 3 h training, the gymnasts performed program routines on three apparatuses. The pre-exercise urine specific gravity (USG) was similar between conditions (LV: 1.018 ± 0.007 vs. HV: 1.015 ± 0.007; p = 0.09), while the post-exercise USG was lower in the HV condition (LV: 1.017 ± 0.006 vs. HV: 1.002 ± 0.003; p < 0.001). Fluid loss corresponding to percentage of body mass was higher in the LV condition (1.2 ± 0.5%) compared to the HV condition (0.4 ± 0.8%) (p = 0.02); however, the sums of the score performances were not different (LV: 26.17 ± 2.04 vs. HV: 26.05 ± 2.00; p = 0.57). Ingesting fluid equivalent to about 50% of the fluid lost, which was the amount that was drunk ad libitum during training, maintained short-term hydration levels and avoided excessive dehydration in artistic preadolescent and adolescent gymnasts. A higher amount of fluid, equivalent to about 1.5 times the fluid loss, did not provide an additional performance benefit.