bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion Products from Metallic Implants Induce ROS and Cell Death in Human Motoneurons In Vitro
Authors: Glaß Hannes , Jonitz-Heincke Anika , Petters Janine , Lukas Jan , Bader Rainer , Hermann Andreas
Published: July 2023

Due to advances in surgical procedures and the biocompatibility of materials used in total joint replacement, more and younger patients are undergoing these procedures. Although state-of-the-art joint replacements can last 20 years or longer, wear and corrosion is still a major risk for implant failure, and patients with these implants are exposed for longer to these corrosive products. It is therefore important to investigate the potential effects on the whole organism. Released nanoparticles and ions derived from commonly used metal implants consist, among others, of cobalt, nickel, and chromium. The effect of these metallic products in the process of osteolysis and aseptic implant loosening has already been studied; however, the systemic effect on other cell types, including neurons, remains elusive. To this end, we used human iPSC-derived motoneurons to investigate the effects of metal ions on human neurons. We treated human motoneurons with ion concentrations regularly found in patients, stained them with MitoSOX and propidium iodide, and analyzed them with fluorescence-assisted cell sorting (FACS). We found that upon treatment human motoneurons suffered from the formation of ROS and subsequently died. These effects were most prominent in motoneurons treated with 500 μM of cobalt or nickel, in which we observed significant cell death, whereas chromium showed fewer ROS and no apparent impairment of motoneurons. Our results show that the wear and corrosive products of metal implants at concentrations readily available in peri-implant tissues induced ROS and subsequently cell death in an iPSC-derived motoneuron cell model. We therefore conclude that monitoring of neuronal impairment is important in patients undergoing total joint replacement.
Biomimetic Nacre-Like Hydroxyapatite/Polymer Composites for Bone Implants
Authors: Tabrizian Parinaz , Sun Huijun , Jargalsaikhan Urangua , Sui Tan , Davis Sean , Su Bo
Published: July 2023

One of the most ambitious goals for bone implants is to improve bioactivity, incapability, and mechanical properties; to reduce the need for further surgery; and increase efficiency. Hydroxyapatite (HA), the main inorganic component of bones and teeth, has high biocompatibility but is weak and brittle material. Cortical bone is composed of 70% calcium phosphate (CaP) and 30% collagen and forms a complex hierarchical structure with anisotropic and lamellar microstructure (osteons) which makes bone a light, strong, tough, and durable material that can support large loads. However, imitation of concentric lamellar structure of osteons is difficult to achieve in fabrication. Nacre from mollusk shells with layered structures has now become the archetype of the natural “model” for bio-inspired materials. Incorporating a nacre-like layered structure into bone implants can enhance their mechanical strength, toughness, and durability, reducing the risk of implant catastrophic failure or fracture. The layered structure of nacre-like HA/polymer composites possess high strength, toughness, and tunable stiffness which matches that of bone. The nacre-like HA/polymer composites should also possess excellent biocompatibility and bioactivity which facilitate the bonding of the implant with the surrounding bone, leading to improved implant stability and long-term success. To achieve this, a bi-directional freeze-casting technique was used to produce elongated lamellar HA were further densified and infiltrated with polymer to produce nacre-like HA/polymer composites with high strength and fracture toughness. Mechanical characterization shows that increasing the ceramic fractions in the composite increases the density of the mineral bridges, resulting in higher flexural and compressive strength. The nacre-like HA/(methyl methacrylate (MMA) + 5 wt.% acrylic acid (AA)) composites with a ceramic fraction of 80 vol.% showed a flexural strength of 158 ± 7.02 MPa and a Young’s modulus of 24 ± 4.34 GPa, compared with 130 ± 5.82 MPa and 19.75 ± 2.38 GPa, in the composite of HA/PMMA, due to the higher strength of the polymer and the interface of the composite. The fracture toughness in the composition of 5 wt.% PAA to PMMA improves from 3.023 ± 0.98 MPa·m1/2 to 5.27 ± 1.033 MPa·m1/2 by increasing the ceramic fraction from 70 vol.% to 80 vol.%, respectively.
A Comparative Investigation of Chemical Decontamination Methods for In-Situ Cleaning of Dental Implant Surfaces
Authors: Hussain Badra , Khan Sadia , Agger Anne Eriksson , Ellingsen Jan Eirik , Lyngstadaas Ståle Petter , Bueno Jaime , Haugen Håvard J.
Published: July 2023

Surface chemistry evaluation is crucial in assessing the efficacy of chemical decontamination products for titanium implants. This study aimed to investigate the effectiveness of chemical decontamination solutions in cleaning a contaminated dental implant surface and to evaluate the potential of combining Pluronic gel with hydrogen peroxide (NuBone®Clean) by evaluating pellicle disruption and re-formation on implant surfaces. In addition, ensuring safety with in vitro and human testing protocols. X-ray Photoelectron Spectroscopy (XPS) was utilised for surface analysis. All the tested gels had some effect on the surface cleanness except for PrefGel®. Among the tested chemical decontamination candidates, NuBone®Clean demonstrated effectiveness in providing a cleaner titanium surface. Furthermore, none of the tested chemical agents exhibited cytotoxic effects, and the safety assessment showed no adverse events. The results of this study highlight the significance of conducting comprehensive evaluations, encompassing safety and efficacy, before introducing new chemical agents for dental treatments. The findings suggest that NuBone®Clean shows potential as a chemical decontamination solution for implant surfaces. However, further investigation through randomised clinical trials is necessary. By adhering to rigorous testing protocols, the development of safe and efficient chemical decontamination strategies can be advanced, benefiting patients and promoting progress in implant dentistry.
AUIE–GAN: Adaptive Underwater Image Enhancement Based on Generative Adversarial Networks
Authors: Guan Fengxu , Lu Siqi , Lai Haitao , Du Xue
Published: July 2023

Underwater optical imaging devices are often affected by the complex underwater environment and the characteristics of the water column, which leads to serious degradation and distortion of the images they capture. Deep learning-based underwater image enhancement (UIE) methods reduce the reliance on physical parameters in traditional methods and have powerful fitting capabilities, becoming a new baseline method for UIE tasks. However, the results of these methods often suffer from color distortion and lack of realism because they tend to have poor generalization and self-adaptation capabilities. Generating adversarial networks (GANs) provides a better fit and shows powerful capabilities on UIE tasks. Therefore, we designed a new network structure for the UIE task based on GANs. In this work, we changed the learning of the self-attention mechanism by introducing a trainable weight to balance the effect of the mechanism, improving the self-adaptive capability of the model. In addition, we designed a feature extractor based on residuals with multi-level residuals for better feature recovery. To further improve the performance of the generator, we proposed a dual path discriminator and a loss function with multiple weighted fusions to help model fitting in the frequency domain, improving image quality. We evaluated our method on the UIE task using challenging real underwater image datasets and a synthetic image dataset and compared it to state-of-the-art models. The method ensures increased enhancement quality, and the enhancement effect of the model for different styles of images is also relatively stable.
Recent Advancement of Bio-Inspired Nanoparticles in Cancer Theragnostic
Authors: Tripathi Divya , Hajra Kasturee , Maity Dipak
Published: July 2023

The introduction of cancer therapeutics and nanotechnology has resulted in a paradigm shift from conventional therapy to precision medicine. Nanotechnology, an interdisciplinary field with a focus on biomedical applications, holds immense promise in bringing about novel approaches for cancer detection, diagnosis, and therapy. The past decade has witnessed significant research and material applications related to nanoparticles (NPs). NPs differ from small-molecule drugs as they possess unique physicochemical characteristics, such as a large surface-to-volume ratio, enabling them to penetrate live cells efficiently. Traditional cancer therapies, such as chemotherapy, radiation therapy, targeted therapy, and immunotherapy, have limitations, such as cytotoxicity, lack of specificity, and multiple drug resistance, which pose significant challenges for effective cancer treatment. However, nanomaterials have unique properties that enable new therapeutic modalities beyond conventional drug delivery in the fight against cancer. Moreover, nanoparticles (1–100 nm) have numerous benefits, such as biocompatibility, reduced toxicity, excellent stability, enhanced permeability and retention effect, and precise targeting, making them ideal for cancer treatment. The purpose of this article is to provide consolidated information on various bio-inspired nanoparticles that aid in cancer theranostics.
Feasibility and Surgical Outcomes of Hybrid Robotic Single-Site Hysterectomy Compared with Single-Port Access Total Laparoscopic Hysterectomy
Authors: Noh Joseph J. , Jeon Jung-Eun , Jung Ji-Hee , Kim Tae-Joong
Published: July 2023

We compared surgical outcomes between single-port access total laparoscopic hysterectomy (SPA-TLH) and hybrid robotic single-site hysterectomy (RSSH), a new technique of combining the benefits of SPA-TLH with RSSH in this study. A total of 64 patients were retrospectively analyzed. They underwent either hybrid RSSH or SPA-TLH for benign gynecologic disease between December 2018 and August 2021. To assess the feasibility of hybrid RSSH, the clinical characteristics and surgical outcomes were compared between the hybrid RSSH group (n = 29) and the SPA-TLH group (n = 35). All of the surgeries were completed without requiring additional ports or conversion to laparotomy. The surgical outcomes including total operative time, uterine weight, estimated blood loss, hemoglobin changes, length of hospital stay, and postoperative pain scores were not significantly different between the two groups. The colpotomy time, including the detachment of the uterosacral and cardinal ligaments, was shorter in the hybrid RSSH group than in the SPA-TLH group (8.0 min vs. 14.0 min; p = 0.029). However, the vaginal cuff closure time was longer in the hybrid RSSH group than in the SPA-TLH group (15.0 min vs.10.0 min; p = 0.001). No difference was observed with regards to intraoperative and postoperative complications. Hybrid RSSH appears to be a feasible procedure for hysterectomy in patients with benign gynecologic diseases.
Early MRI Predictors of Relapse in Primary Central Nervous System Lymphoma Treated with MATRix Immunochemotherapy
Authors: Cornell Isabel , Al Busaidi Ayisha , Wastling Stephen , Anjari Mustafa , Cwynarski Kate , Fox Christopher P. , Martinez-Calle Nicolas , Poynton Edward , Maynard John , Thust Steffi C.
Published: July 2023

Primary Central Nervous System Lymphoma (PCNSL) is a highly malignant brain tumour. We investigated dynamic changes in tumour volume and apparent diffusion coefficient (ADC) measurements for predicting outcome following treatment with MATRix chemotherapy in PCNSL. Patients treated with MATRix (n = 38) underwent T1 contrast-enhanced (T1CE) and diffusion-weighted imaging (DWI) before treatment, after two cycles and after four cycles of chemotherapy. Response was assessed using the International PCNSL Collaborative Group (IPCG) imaging criteria. ADC histogram parameters and T1CE tumour volumes were compared among response groups, using one-way ANOVA testing. Logistic regression was performed to examine those imaging parameters predictive of response. Response after two cycles of chemotherapy differed from response after four cycles; of the six patients with progressive disease (PD) after four cycles of treatment, two (33%) had demonstrated a partial response (PR) or complete response (CR) after two cycles. ADCmean at baseline, T1CE at baseline and T1CE percentage volume change differed between response groups (0.005 < p < 0.038) and were predictive of MATRix treatment response (area under the curve: 0.672–0.854). Baseline ADC and T1CE metrics are potential biomarkers for risk stratification of PCNSL patients early during remission induction therapy with MATRix. Standard interim response assessment (after two cycles) according to IPCG imaging criteria does not reliably predict early disease progression in the context of a conventional treatment approach.
Impact of Stepwise Recruitment Maneuvers on Cerebral Hemodynamics: Experimental Study in Neonatal Model
Authors: Torre Oñate Teresa , Romero Berrocal Antonio , Bilotta Federico , Badenes Rafael , Santos Gonzalez Martin , de Reina Perez Laura , Garcia Fernandez Javier
Published: July 2023

Background: Lung recruitment maneuvers (LRMs) have been demonstrated to be effective in avoiding atelectasis during general anesthesia in the pediatric population. Performing these maneuvers is safe at the systemic hemodynamic and respiratory levels. Aims: We aimed to evaluate the impact of a stepwise LRM and individualized positive end-expiratory pressure (PEEP) on cerebral hemodynamics in an experimental neonatal model. Methods: Eleven newborn pigs (less than 72 h old, 2.56 ± 0.18 kg in weight) were included in the study. The LRM was performed under pressure-controlled ventilation with a constant driving pressure (15 cmH2O) in a stepwise increasing PEEP model. The target peak inspiratory pressure (PIP) was 30 cmH2O and the PEEP was 15 cmH2O. The following hemodynamic variables were monitored using the PICCO® system: mean arterial pressure (MAP), central venous pressure (CVP), and cardiac output (CO). The cerebral hemodynamics variables monitored were intracranial pressure (ICP) (with an intraparenchymal Camino® catheter) and cerebral oxygen saturation (rSO2) (with the oximetry monitor INVOS 5100® system). The following respiratory parameters were monitored: oxygen saturation, fraction of inspired oxygen, partial pressure of oxygen, end-tidal carbon dioxide pressure, Pmean, PEEP, static compliance (Cstat), and dynamic compliance (Cdyn). Results: All LRMs were safely performed as scheduled without any interruptions. Systemic hemodynamic stability was maintained during the lung recruitment maneuver. No changes in ICP occurred. We observed an improvement in rSO2 after the maneuver (+5.8%). Conclusions: Stepwise LRMs are a safe tool to avoid atelectasis. We did not observe an impairment in cerebral hemodynamics but an improvement in cerebral oxygenation.
A Set of Rules for Function-Oriented Automatic Multi-Sentence Analysis in Patents
Authors: Spreafico Christian , Spreafico Matteo
Published: July 2023

This study proposes some rules for performing a function-oriented search (providing function and object) to extract technical systems from patents, using syntax and dependency patterns to analyse multiple sentences. Unlike the most common inter-sentence analysis methods, the proposed method does not use context information or distance to link the elements of several sentences, but generic terms from patent ontology. The content provided by the rules was entirely derived from a statistical analysis of many patents from different domains, in order to provide a general validity for the rules. The application of the method in two case studies, related to metal cutting and manure processing, highlighted its main advantages. Its degree of automation is such that the expert is almost exclusively excluded, except in the definition of the function on which to build the document pool. The precision and the recall of the results during the tests exceeded 90%. The current limitation concerns the manual control of some results, about 25%, which derive from an additional set of dependency patterns that are difficult to automate and deserve further investigation. The technical systems are many more in number and are more detailed with regard to structural aspects than those obtainable by analysing only single sentences and/or syntax.
The Flow Matrix Offers a Straightforward Alternative to the Problematic Markov Matrix
Authors: Strzempko Jessica , Pontius Robert Gilmore
Published: July 2023

The Flow matrix is a novel method to describe and extrapolate transitions among categories. The Flow matrix extrapolates a constant transition size per unit of time on a time continuum with a maximum of one incident per observation during the extrapolation. The Flow matrix extrapolates linearly until the persistence of a category shrinks to zero. The Flow matrix has concepts and mathematics that are more straightforward than the Markov matrix. However, many scientists apply the Markov matrix by default because popular software packages offer no alternative to the Markov matrix, despite the conceptual and mathematical challenges that the Markov matrix poses. The Markov matrix extrapolates a constant transition proportion per time interval during whole-number multiples of the duration of the calibration time interval. The Markov extrapolation allows at most one incident per observation during each time interval but allows repeated incidents per observation through sequential time intervals. Many Markov extrapolations approach a steady state asymptotically through time as each category size approaches a constant. We use case studies concerning land change to illustrate the characteristics of the Flow and Markov matrices. The Flow and Markov extrapolations both deviate from the reference data during a validation time interval, implying there is no reason to prefer one matrix to the other in terms of correspondence with the processes that we analyzed. The two matrices differ substantially in terms of their underlying concepts and mathematical behaviors. Scientists should consider the ease of use and interpretation for each matrix when extrapolating transitions among categories.
Cerebral Vasomotor Reactivity in COVID-19: A Narrative Review
Authors: Ghotbi Zahra , Estakhr Mehrdad , Hosseini Melika , Shahripour Reza Bavarsad
Published: July 2023

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) primarily affects the respiratory system but can also lead to neurological complications. Among COVID-19 patients, the endothelium is considered the Achilles heel. A variety of endothelial dysfunctions may result from SARS-CoV-2 infection and subsequent endotheliitis, such as altered vascular tone, oxidative stress, and cytokine storms. The cerebral hemodynamic impairment that is caused is associated with a higher probability of severe disease and poor outcomes in patients with COVID-19. This review summarizes the most relevant literature on the role of vasomotor reactivity (VMR) in COVID-19 patients. An overview of the research articles is presented. Most of the studies have supported the hypothesis that endothelial dysfunction and cerebral VMR impairment occur in COVID-19 patients. Researchers believe these alterations may be due to direct viral invasion of the brain or indirect effects, such as inflammation and cytokines. Recently, researchers have concluded that viruses such as the Human Herpes Virus 8 and the Hantavirus predominantly affect endothelial cells and, therefore, affect cerebral hemodynamics. Especially in COVID-19 patients, impaired VMR is associated with a higher risk of severe disease and poor outcomes. Using VMR, one can gain valuable insight into a patient’s disease progression and make more informed decisions regarding appropriate treatment options. A new pandemic may develop with the COVID-19 virus or other viruses, making it essential that healthcare providers and researchers remain focused on developing new strategies for improving survival in such patients, particularly those with cerebrovascular risk factors.
Bacterial Contamination in Total Joint Replacement: Should We Change into a New Set of Clean Scrub Suits Whenever Entering the Operating Room?
Authors: Tateiwa Toshiyuki , Takahashi Yasuhito , Ishida Tsunehito , Masaoka Toshinori , Shishido Takaaki , Yamamoto Kengo
Published: July 2023

Background: The aims of this study are as follows: (1) to investigate the level and probability of bacterial contamination on scrub suits over time for medical personnel working inside and/or outside the operating room (OR) area; (2) to discuss the protective role of cover gowns against bacterial contamination; and (3) to consider the necessity of changing into clean suits whenever entering the OR in terms of preventing periprosthetic joint infection (PJI) in total joint replacement (TJR). Methods: The bacterial colony count was examined on the chest area of the scrub suits worn during various daily clinical practices. The genus/species of the contaminants were identified by matrix-assisted laser deposition ionization-time of flight mass spectrometry (MALDI-TOF MS). Results: The scrub suits worn outside the OR area showed a greater level of bacterial contamination than those worn inside the OR area, although the colony counts tended to increase over time both in and out of the area. The probability of contamination involving coagulase-negative staphylococci (CNS) (known as the primary cause of PJI) did not increase significantly in the scrubs worn inside the OR area, but did increase significantly after a long-time departure from the OR area. Conclusions: Our results suggest that wearing scrub suits outside and/or the long duration of wearing the same suits can significantly increase the level and probability of any bacterial contamination (including CNS) on scrub suits. We also found that wearing a cover gown over scrub suits outside the OR area may have only a limited protective role against bacterial contamination.
Comparison of Smoothness, Movement Speed and Trajectory during Reaching Movements in Real and Virtual Spaces Using a Head-Mounted Display
Authors: Kato Norio , Iuchi Tomoya , Murabayashi Katsunobu , Tanaka Toshiaki
Published: July 2023

Virtual reality is used in rehabilitation and training simulators. However, whether movements in real and virtual spaces are similar is yet to be elucidated. The study aimed to examine the smoothness, trajectory, and velocity of participants’ movements during task performance in real and virtual space. Ten participants performed the same motor task in these two spaces, reaching for targets placed at six distinct positions. A head-mounted display (HMD) presented the virtual space, which simulated the real space environment. The smoothness of movements during the task was quantified and analysed using normalised jerk cost. Trajectories were analysed using the actual trajectory length normalised by the shortest distance to the target, and velocity was analysed using the time of peak velocity. The analysis results showed no significant differences in smoothness and peak velocity time between the two spaces. No significant differences were found in the placement of the six targets between the two spaces. Conversely, significant differences were observed in trajectory length ratio and peak velocity time, albeit with small effect sizes. This outcome can potentially be attributed to the fact that the virtual space was presented from a first-person perspective using an HMD capable of presenting stereoscopic images through binocular parallax. Participants were able to obtain physiological depth information and directly perceive the distance between the target and the effector, such as a hand or a controller, in virtual space, similar to real space. The results suggest that training in virtual space using HMDs with binocular disparity may be a useful tool, as it allows the simulation of a variety of different environments.
Physiologically Aggregated LacZ Applied in Trehalose Galactosylation in a Recycled Batch Mode
Authors: Belkova Martina , Janegova Tatiana , Hrabarova Eva , Nahalka Jozef
Published: July 2023

Galactooligosaccharides obtained via β-galactosidase transgalactosylation have health-promoting properties and are widely recognized as effective prebiotics. Trehalose-based galactooligosaccharides could be introduced into food and pharmaceutical industries similarly to trehalose. In light of this, new technological approaches are needed. Recently, in vivo enzyme immobilizations for recombinant proteins have been introduced, and physiological aggregation into active inclusion bodies (aIBs) has emerged as one such method of in vivo immobilization. To prepare LacZ β-galactosidase in the form of aIBs, we used a short 10 amino acid aggregation-prone tag. These native protein particles were simply washed from the cell lysate and applied in trehalose galactosylation in a recycled batch mode. In this study, aIBs entrapped in alginate beads, encapsulated in alginate/cellulose sulfate/poly(methylene-co-guanidine) capsules and magnetized were compared with free aIBs. Alginate/cellulose sulfate/PMCG capsules showed more suitable properties and applicability for biotransformation of trehalose at its high concentration (25%, w/v) and elevated temperature (50 °C).
Comparison of Different Standard Test Methods for Evaluating Greases for Rolling Bearings under Vibration Load or at Small Oscillation Angles
Authors: Grebe Markus , Widmann Alexander
Published: July 2023

Rolling bearings operated at small oscillation angles or exposed to vibrations during standstill show typical damage after only a short period of operation. This can be false brinelling damage, so-called standstill marks or classic fretting damage (fretting corrosion, tribo-oxidation). It is important to differentiate here according to the amplitude-ratio x/2b, which indicates the ratio between the rolling element Motion (x) and the Hertzian contact half-axis (b). Depending on this ratio, suitable laboratory test methods must be used to test the lubricating grease practically for the particular application. For this purpose, the Fafnir wear test, according to the standard of the American Society for Testing and Materials ASTM D4170, is also listed in the current high-performance multi-use specification of the National Lubricating Grease Institute (NLGI) as a release test for lubricating greases. In Europe, the SNR-FEB2 test is frequently used, which is also required to release greases in the blade bearings of wind turbines, among other things. In the case of standstill marks due to very small oscillation angles or vibrations, the Mannheim Tribology Competence Center (KTM) has developed a special test now established in the industry. The oscillating angles vary in these three different standard tests in the range from ±6° in the Fafnir test to ±3° in the SNR-FEB2 test to ±0.5° in the KTM standstill marking test; the x-to-2b ratios range from 5.5 (Fafnir) to 3.4 (SNR) to 0.5 (KTM). This paper will explain the scientific basis for these special operating and test conditions and compare test results of specially prepared model greases in these three standard rolling bearing tests, two test variations and a classical fretting test under oscillating sliding friction (ASTM D7594). The paper’s main objective is to show that the suitability of grease for such an application depends strongly on the prevailing operating conditions. Different tests in this field are, therefore, not interchangeable. Good results in one test do not automatically mean good results in a similar test at first glance. Therefore, selecting the right test for the application is important.
High Temperature Friction and Wear Behavior of PTFE/MoS2 Composites
Authors: Zhen Jinming , Han Yunxiang , Wang Huabao , Jiang Zhenguo , Wang Li , Huang Yuqiang , Jia Zhengfeng , Zhang Ran
Published: July 2023

High performance polymer matrix composites with low friction and wear rate are of urgent requirement in sliding bearings and gaskets. In this study, the PTFE/MoS2 composites were prepared and the effect of testing temperature on the tribological properties were investigated. Results show that the friction coefficient and wear rate are approximately (0.14–0.19) and (4.18–13.38 × 10−4 mm3/Nm) at testing temperatures from 25 to 250 °C, respectively. At testing temperatures above 200 °C, the coefficient of friction of the composite with the addition of MoS2 is lower than that of pure PTFE, while the wear rate of the composite material with the addition of 2 wt.% and 5 wt.% MoS2 is lower than that of pure PTFE at temperatures above 150 °C. At low testing temperatures (25–100 °C), the main wear mechanism is that of slight abrasive wear, while from 150 °C to 250 °C, the main wear mechanism transformed to fatigue and severe abrasive wear.
Analytical, Numerical and Experimental Analysis of a Positive Displacement Cam Mechanism—A Case Study
Authors: Merticaru Eugen , Merticaru Vasile , Nagîț Gheorghe , Mihalache Andrei Marius , Tăbăcaru Liviu Lucian , Rîpanu Marius Ionuț
Published: July 2023

Cam mechanisms, covering a large structural variety, are widely used in machinery, mainly as components of automated systems. Their functioning behavior is affected by negative dynamic phenomena determined by specific high velocities and acceleration rates. Within the various types of research on the dynamic behavior of cam mechanisms, this study addresses the need to clarify the influence of geometrical parameters and technological conditions on some indicators of the jump phenomenon in contact loss for a cam-follower mechanism. This particularly developed case study referred to a mechanism with a profiled grooved disk cam and oscillating follower. To highlight the influence of the cam-follower contact elasticity on the jump phenomenon, two dynamic models were developed: one considering rigid elements in contact and the second considering elastic cam-follower contact. The models were tested within a virtually simulated experiment, and the numerical simulation results evidenced the influence of input factors like the applied load on the mechanism, the clearance in the cam-follower kinematic pair, and the rotational speed of the cam, and the inertia moment was reduced to the follower on some indicators of the jump phenomenon. Validation FEA and experiments were performed, proving the reliable appropriateness of the dynamic model based on elastic cam-follower contact.
Oxo-Additives for Polyolefin Degradation: Kinetics and Mechanism
Authors: Mamin Eldar A. , Pantyukhov Petr V. , Olkhov Anatoly A.
Published: July 2023

This review considers the recent investigations in the scope of biodegradability of synthetic polymers, spanning polyethylene (PE), polypropylene (PP), and their corresponding composites, with a focus on the influence of oxo-additives (mostly transition metal salts). The types of oxo-additives and the mechanisms of oxidation acceleration are discussed. Furthermore, the influence of oxo-additives on both physicochemical and biological stages of degradation is evaluated (laboratory and field experiments with microorganisms/fungi action) with recent standards suggested for degradation estimation. Comparisons of the metal salts are given with respect to catalysis, as well as the synergetic influence of additives. The additives presented on the commercial market are also discussed.
A Novel Light U-Net Model for Left Ventricle Segmentation Using MRI
Authors: Irshad Mehreen , Yasmin Mussarat , Sharif Muhammad Imran , Rashid Muhammad , Sharif Muhammad Irfan , Kadry Seifedine
Published: July 2023

MRI segmentation and analysis are significant tasks in clinical cardiac computations. A cardiovascular MR scan with left ventricular segmentation seems necessary to diagnose and further treat the disease. The proposed method for left ventricle segmentation works as a combination of the intelligent histogram-based image enhancement technique with a Light U-Net model. This technique serves as the basis for choosing the low-contrast image subjected to the stretching technique and produces sharp object contours with good contrast settings for the segmentation process. After enhancement, the images are subjected to the encoder–decoder configuration of U-Net using a novel lightweight processing model. Encoder sampling is supported by a block of three parallel convolutional layers with supporting functions that improve the semantics for segmentation at various levels of resolutions and features. The proposed method finally increased segmentation efficiency, extracting the most relevant image resources from depth-to-depth convolutions, filtering them through each network block, and producing more precise resource maps. The dataset of MICCAI 2009 served as an assessment tool of the proposed methodology and provides a dice coefficient value of 97.7%, accuracy of 92%, and precision of 98.17%.
Discontinuous Economic Growing Quantity Inventory Model
Authors: Nobil Amir Hossein , Nobil Erfan , Cárdenas-Barrón Leopoldo Eduardo , Garza-Núñez Dagoberto , Treviño-Garza Gerardo , Céspedes-Mota Armando , Loera-Hernández Imelda de Jesús , Smith Neale R.
Published: July 2023

The classical economic growing quantity (EGQ) model is a key concept in the inventory control problems research literature. The EGQ model is commonly employed for the purpose of inventory control in the management of growing items, such as fish and farm animals, within industries such as livestock, seafood, and aviculture. The economic order quantity (EOQ) model assumes that customer demand is satisfied without interruption in each cycle; however, this assumption is not always true for some companies as they do not have continuous operations, except for item storage, during non-working times such as weekends, natural idle periods, or spare time. In this study, we extend the traditional EGQ model by incorporating the concept of working and non-working periods, resulting in the development of a new model called discontinuous economic growing quantity (DEGQ). Unlike the conventional EGQ model, the DEGQ model considers the presence of intermittent operational periods, in which the firm is actively engaged in its activities, and non-working periods, during which only storage-related operations occur. By incorporating this discontinuity, the DEGQ model provides a more accurate representation of real-world scenarios where businesses operate in a non-continuous manner, thus enhancing the effectiveness of inventory control and management strategies. The study aims to obtain the optimal number of periods in each cycle and the optimal slaughter age for the breeding items, and, subsequently, to find the optimal order size to minimize the total cost. Finally, we propose an optimal analytical procedure to determine the optimal solutions. This procedure entails finding the optimal number of periods using a closed-form equation and determining the optimal slaughter age by exhaustively searching the entire range of possible growth times.
Quality Standard for Rehabilitation of Young Deaf Children Receiving Cochlear Implants
Authors: De Raeve Leo , Cumpăt Marinela-Carmen , van Loo Aimée , Costa Isabel Monteiro , Matos Maria Assunção , Dias João Canossa , Mârțu Cristian , Cavaleriu Bogdan , Gherguț Alois , Maftei Alexandra , Tudorean Ovidiu-Cristian , Butnaru Corina , Șerban Roxana , Meriacre Tatiana , Rădulescu Luminița
Published: July 2023

Background and objectives: More and more children with severe-to-profound hearing loss are receiving cochlear implants (CIs) at an early age to improve their hearing and listening abilities, speech recognition, speech intelligibility, and other aspects of spoken language development. Despite this, the rehabilitation outcomes can be very heterogeneous in this population, not only because of issues related to surgery and fitting or the specific characteristics of the child with his/her additional disabilities but also because of huge differences in the quality of the support and rehabilitation offered by the therapist and the family. These quality standards for the rehabilitation of young deaf children receiving CIs are developed within the European KA202 Erasmus+ project “VOICE”—vocational education and training for speech and language therapists and parents for the rehabilitation of children with CIs, Ref. No.: 2020-1-RO01-KA202-080059. Material and methods: To develop these quality standards, we used the input from the face-to-face interviews of 11 local rehabilitation experts in CIs from the four partner countries of the project and the outcomes of the bibliographic analysis of 848 publications retrieved from six databases: Pub Med, Psych Info, CINAHL, Scopus, Eric, and Cochrane. Based on all this information, we created a first set of 32 quality standards over four domains: general, fitting, rehabilitation, and for professionals. Further on, the Delphi method was used by 18 international rehabilitation experts to discuss and agree on these standards. Results: The results from the literature analysis and the interviews show us that more than 90% of the consulted international experts agreed on 29 quality standards. They focus on different aspects of rehabilitation: the multidisciplinary team, their expertise and knowledge, important rehabilitation topics to focus on, and programming issues related to rehabilitation. Conclusions: These quality standards aim to optimize the activity of speech rehabilitation specialists so that they reach the optimal level of expertise. Also presented is the necessary equipment for the IC team to carry out the rehabilitation sessions in good conditions. This set of quality standards can be useful to ensure the appropriate postoperative care of these children. As a result, the rehabilitation process will be more relaxed, and therapists will have the opportunity to focus more on the specific needs of each child, with the provision of quality services, which will result in better results. This theme is particularly complex and dependent on multifactorial aspects of medicine, education, speech therapy, social work, and psychology that are very intricate and interdependent.
The Effects of Cardiac Rehabilitation including Nordic Walking in Patients with Chronic Coronary Syndromes after Percutaneous Coronary Interventions in Elective Mode
Authors: Januszek Rafał , Kocik Bożena , Siłka Wojciech , Gregorczyk-Maga Iwona , Mika Piotr
Published: July 2023

Background: Percutaneous coronary intervention (PCI) in patients with chronic coronary syndrome (CCS) is a worldwide method of coronary revascularisation. The aim of this study was to assess the immediate and long-term effects of Nordic Walking (NW) training added to a standard cardiac rehabilitation programme on physical activity (PA) and capacity and life quality, as well as selected proatherogenic risk factors. Methods: The studied group comprised 50 patients (considering exclusion criteria, 40 patients), aged 56–70, with CCS after elective PCI qualified them for a 6-weeks-long cardiac rehabilitation. The follow-up period lasted 4 months, and control visits occurred at 2 and 4 months. The studied patients were randomly divided into two groups: control group—standard cardiac rehabilitation programme and experimental group—standard cardiac rehabilitation programme additionally combined with NW training. Results: The cardiac rehabilitation programme in the experimental, compared to the control group, increased intense PA (from 731.43 ± 909.9 to 2740 ± 2875.96 vs. from 211.43 ± 259.43 to 582.86 ± 1289.74 MET min/week) and aerobic efficiency—VO2peak (from 8.67 ± 0.88 to 9.96 ± 1.35 vs. from 7.39 ± 2 to 7.41 ± 2.46 METs), as well as quality of life according to the WHOQOL-BREF questionnaire (from 3.57 ± 0.51 to 4.14 ± 0.36 vs. from 3.29 ± 0.47 to 3.57 ± 0.51 points). The walking distance assessed with the 6-min walk test did not differ between the groups before the beginning of the rehabilitation programme. Both at the I follow-up and II follow-up time points, a significant increase in the walking distance was noted in the control and experimental groups compared to baseline, and the difference between both groups was significant at the end of follow-up (378.57 ± 71.35 vs. 469.29 ± 58.07, p = 0.003). Moreover, NW had a positive effect on the modulation within selected biochemical risk factors of atherosclerosis, as well as subjective quality of life and well-being. Conclusions: Introducing NW training into the cardiac rehabilitation process proved to be a more effective form of therapy in patients with CCS treated via PCI, as compared to the standard cardiac rehabilitation programme alone.
Introduction to the Topic of the Special Issue “Progresses and Challenges of Block Copolymer Membranes” from the Guest Editor
Authors: Davletbaeva Ilsiya M. , Sazonov Oleg O.
Published: July 2023

It is well-known that various mixtures that require separation have to be dealt with in many branches of industry, especially the chemical and petrochemical industries [...]
Preparation of Thin Film Composite (TFC) Membrane with DESPs Interlayer and Its Forward Osmosis (FO) Performance for Organic Solvent Recovery
Authors: Liang Jingyi , Huang Hansheng , Zhang Hao , Wu Yanhui , Zhuang Yongbing
Published: July 2023

To explore the application of forward osmosis (FO) technology in the organic solvent recovery field, we prepared a new solvent-resistant triple layer thin film composite (TFC) membrane on the PI (polyimide) substrate. The deep eutectic supramolecular polymers (DESPs) interlayer was constructed on the substrate to improve the separation performance and solvent resistance. DESPs interlayer was formed by mixing and heating with cyclodextrin as the hydrogen bond acceptor and L-malic acid as the hydrogen bond donor. The chemical changes, surface property and morphology of the composite membrane with DESPs interlayer were characterized. The separation performance and stability of the triple layer composite membrane in organic solvent FO were studied. For the monascorubrin-ethanol system, the permeation flux of TFC/DESPs5-PI membrane could reach 9.51 LMH while the rejection rate of monascorubrin was 98.4% (1.0 M LiCl/ethanol as draw solution), which was better than the pristine membrane. Therefore, this solvent-resistant triple layer composite FO membrane has good potential for the recovery of organic solvents.
Design and Optimization of a Novel Hybrid Membrane–Electrochemical Hydrogen Pump Process for Recovering Helium from NRU off Gas
Authors: Xiao Wu , Wang Hao , Cheng Andi , Wang Hanli , Yang Zhendong , Wu Xuemei , Jiang Xiaobin , He Gaohong
Published: July 2023

Due to the low boiling point of helium, the nitrogen-rich off gas of the nitrogen rejection unit (NRU) in the liquefied natural gas (LNG) plant usually contains a small amount of CH4, approximately 1–4% He, and associated gases, such as H2. However, it is difficult to separate hydrogen and helium. Here, we propose two different integrated processes coupled with membrane separation, pressure swing adsorption (PSA), and the electrochemical hydrogen pump (EHP) based on different sequences of hydrogen gas removal. Both processes use membrane separation and PSA in order to recover and purify helium, and the EHP is used to remove hydrogen. The processes were strictly simulated using UniSim Design, and an economic assessment was conducted. The results of the economic assessment show that flowsheet #2 was more cost-effective due to the significant reduction in the capacity of the compressor and PSA because of the pre-removal of hydrogen. Additionally, using the response surface methodology (RSM), a Box–Behnken design experiment was conducted, and an accurate and reliable quadratic response surface regression model was fitted through variance analysis. The optimized operating parameters for the integrated process were determined as follows: the membrane area of M101 was 966.6 m2, the permeate pressure of M101 was 100 kPa, and the membrane area of M102 was 41.2 m2. The maximum recovery fraction was 90.66%, and the minimum cost of helium production was 2.21 $/kg. Thus, proposed flowsheet #2 has prospects and value for industrial application.
Improvement of MBBR-MBR Performance by the Addition of Commercial and 3D-Printed Biocarriers
Authors: Banti Dimitra C. , Samaras Petros , Kostopoulou Eleni , Tsioni Vassiliki , Sfetsas Themistoklis
Published: July 2023

Moving bed biofilm reactor combined with membrane bioreactor (MBBR-MBR) constitute a highly effective wastewater treatment technology. The aim of this research work was to study the effect of commercial K1 biocarriers (MBBR-MBR K1 unit) and 3D-printed biocarriers fabricated from 13X and Halloysite (MBBR-MBR 13X-H unit), on the efficiency and the fouling rate of an MBBR-MBR unit during wastewater treatment. Various physicochemical parameters and trans-membrane pressure were measured. It was observed that in the MBBR-MBR K1 unit, membrane filtration improved reaching total membrane fouling at 43d, while in the MBBR-MBR 13X-H and in the control MBBR-MBR total fouling took place at about 32d. This is attributed to the large production of soluble microbial products (SMP) in the MBBR-MBR 13X-H, which resulted from a large amount of biofilm created in the 13X-H biocarriers. An optimal biodegradation of the organic load was concluded, and nitrification and denitrification processes were improved at the MBBR-MBR K1 and MBBR-MBR 13X-H units. The dry mass produced on the 13X-H biocarriers ranged at 4980–5711 mg, three orders of magnitude larger than that produced on the K1, which ranged at 2.9–4.6 mg. Finally, it was observed that mostly extracellular polymeric substances were produced in the biofilm of K1 biocarriers while in 13X-H mostly SMP.
Advances in Metal-Containing Magnetic Materials and Magnetic Technologies
Authors: Liu Zhongwu
Published: July 2023

Magnetic materials generally refer to materials with ferromagnetic or ferrimagnetic ordering [...]
Comparative Analysis of the Hot Isostatic Pressing Densification Behavior of Uniform and Non-Uniform Distributed Powder
Authors: Meng Fandi , Lang Lihui , Xiao Yi
Published: July 2023

Hot isostatic pressing (HIP) technology can directly produce nearly clean shaped workpieces that meet the requirements while ensuring machining accuracy and surface quality. Usually, people use numerical simulation methods to reduce experimental costs. Generally, a uniform powder relative density distribution of about 65% is used in the simulation. However, in practical engineering, we found that even with additional tools such as vibration tables, the powder filling is not uniform. The non-uniform distribution causes uneven shrinkage of the powder and capsule after HIP. In this paper, a numerical model for HIPing of Ti-6Al-4V powder is developed to improve the prediction by comparing the uniform and non-uniform initial powder distribution. The results show that different initial relative density distributions affect the powder densification process and further affect the deformation of the capsule. It also leads to non-uniform stress distribution after HIP, which increases the risk of capsule rupture. The analysis of the numerical simulation results and the comparison with the experimental results highlights that taking into account the non-uniform powder distribution inside the capsule is vital to improve numerical results and produce near-net shape components. The maximum error of the simulation with the usual initial relative density setting of 65% is 4.2%. However, considering the uneven distribution of initial powder, the maximum error is reduced to 3.16%, and the average error is also less than 2%.
Microstructure and Properties in Metals and Alloys
Authors: Di Schino Andrea , Testani Claudio
Published: July 2023

Microstructure design is key in targeting the desired material’s properties [...]