Study of Interfacial Adhesion and Re-Ir Alloy Coating in Chalcogenide Glass Molding.

Precision glass molding (PGM) has become an efficacious technique to fabricate high-precision optics. Chalcogenide (ChG) glass is increasingly used in thermal imaging, night vision, etc., because of its excellent infrared optical properties. Nevertheless, glass-mold interfacial adhesion has emerged as a pivotal issue within the PGM process. The interfacial adhesion during PGM has the potential to significantly undermine the performance of molded optics and reduce the longevity of molds. It is important to investigate interfacial adhesion behaviors in the PGM. In this study, the interfacial adhesion mechanism between ChG glass and the nickel-phosphorus (Ni-P) mold is analyzed using the cylindrical compression test. The effect of ChG glass internal stress on physical adhesion is investigated by finite element method (FEM) simulation. The spherical preform is proven to be capable of reducing the stress concentration and preventing physical adhesion. More importantly, a rhenium-iridium (Re-Ir) alloy coating is deposited on the Ni-P mold surface by ion sputtering to prevent atomic diffusion and resolve the problem of chemical adhesion. Finally, ChG glass microstructures with high accuracy are fabricated using the spherical ChG glass preform and the Re-Ir-coated Ni-P mold by PGM.

Surface defect analysis on formed chalcogenide glass Ge22Se58As20 lenses after the molding process.

Chalcogenide glass (ChG) is increasingly used in infrared optical systems owing to its excellent infrared optical properties and scalable production using precision glass molding (PGM). However, surface scratches affected by the molding temperature and microdimples on the lens surface caused by gas release seriously impair the quality of the formed lens. To reduce these surface defects when molding Ge22Se58As20 ChG, the temperature effect must be studied, and the gas generation must be minimized, while the gas escape must be maximized. In this work, we studied the effect of temperature on the surface defects. Additionally, we studied the influences of the roughness and curvature of the contact surfaces, as well as the pressing force on the formation of the microdimples. It was found that the molding temperature should be approximately 30°C higher than the softening temperature (Ts) to avoid surface scratches. The gas generation could be inhibited by increasing the pressing force and decreasing the roughness of the mold surface, and finally, increasing the curvature difference between the mold and glass preform surfaces improved the gas escape.

Structural Evolution in Glassy Carbon Investigated Based on the Temperature Dependence of Young's Modulus.

As a non-graphitized carbon material, possessing exceptional hardness and chemical inertness, glassy carbon (GC) is often synthesized through the pyrolysis method, which includes a compression procedure of powdered precursor materials, thus increasing the costs for production of glassy carbon at an industrial scale. Direct preparation of GC via pyrolysis of bulk precursors is a low-cost approach but encounters challenges arising from an insufficient knowledge of carbon structure formation. In order to solve this problem, a new analysis of the temperature-dependent variation in Young's modulus of GC obtained by the pyrolysis of phenolic resin at 1000 °C, utilizing the impulse excitation technique (IET), was performed. Our findings demonstrate that there is a critical temperature range of 500-600 °C where pyrolysis leads to the most significant density change and GC is formed as a result. When GC samples are heated again, a significant structural reformation occurs in the same temperature range. It causes a decrease in stiffness, especially at heating rates >3 °C/min, and an interesting restorative effect-increase in stiffness when a GC sample is annealed at temperatures of 500-550 °C. These results bring important implications for the direct formation of large amounts of glassy carbon using bulk precursors.

A bar-joint model based on the corrected resistive force theory for artificial flagellated micro-swimmers propelled by acoustic waves.

In this work, we proposed a bar-joint model based on the corrected resistive force theory (CRFT) for studying artificial flagellated micro-swimmers (AFMSs) propelled by acoustic waves in a two-dimensional (2D) flow field or with a rectangular cross-section. Note that the classical resistive-force theory for 3D cylindrical flagellum leads to over 90% deviation in terminal velocity from those of 2D fluid-structure interaction (FSI) simulations, while the proposed CRFT bar-joint model can reduce the deviation to below 5%; hence, it enables a reliable prediction of the 2D locomotion of an acoustically actuated AFMS with a rectangular cross-section, which is the case in some experiments. Introduced in the CRFT is a single correction factorKdetermined by comparing the linear terminal velocities under acoustic actuation obtained from the CRFT with those from simulations. After the determination ofK, detailed comparisons of trajectories between the CRFT-based bar-joint AFMS model and the FSI simulation were presented, exhibiting an excellent consistency. Finally, a numerical demonstration of the purely acoustic or magneto-acoustic steering of an AFMS based on the CRFT was presented, which can be one of the choices for future AFMS-based precision therapy.

Frailty is associated with 90-day unplanned readmissions and death in patients with heart failure: A longitudinal study in China.

BACKGROUND: Frailty has been reported to be significantly associated with adverse health outcomes in people with heart failure (HF). OBJECTIVES: To explore the potential effects of frailty on unplanned readmissions and death in people with HF patients aged 18 years or older. METHODS: 342 HF patients aged 18 years or older from the heart centers of two different tertiary care hospitals located in northwest of China were enrolled between July and December 2020. Frailty was assessed by the Tilburg Frailty Indicator. The patients were followed for unplanned readmissions, and all-cause mortality at 30, 60, as well as 90 days after discharge. Multivariate cox regression models were used to analyze the effects of frailty on 90-day unplanned readmission and death in the patients with HF. RESULTS: Frailty prevalence was 54.7% among 342 HF patients, with a mean age of 64.65 ± 11.90 years. It was found that compared to non-frailty HF patients, the frailty HF patients were older and displayed higher systolic blood pressure, longer duration of HF, more severe cognitive function, and more comorbidities (P < 0.05). On the contrary, the patients in the frail group had a higher incidence of unplanned readmission (73.1% vs. 26.9%, χ2 = 18.87, P < 0.01) and death (100% vs. 0%, χ2 = 6.94, P < 0.01) than those in the non-frail group. Multivariate cox regression analysis showed that frailty could serve as an independent risk factor for 90-day unplanned readmission (HR = 1.469, 95% CI 1.318-1.637, P < 0.01) and 90-day death (HR=2.270, 95% CI 1.091-4.726, P < 0.01) in the patients with HF. CONCLUSION: Frailty can act as an independent predictor of unplanned readmission and death 90-day after discharge in HF patients aged 18 years or older.

Configurational Entropy Effects on Glass Transition in Metallic Glasses.

Configurational entropy (Sconf) is known to be a key thermodynamic factor governing a glass transition process. However, this significance remains speculative because Sconf is not directly measurable. In this work, we demonstrate the role of Sconf theoretically and experimentally by a comparative study of a Zr-Ti-Cu-Ni-Be high-entropy metallic glass (HE-MG) with one of its conventional MG counterparts. It is revealed that the higher Sconf leads to a glass that is energetically more stable and structurally more ordered. This is manifested by ab initio molecular dynamics simulations, showing that ∼60% fewer atoms are agitated above Tg, and experimental results of smaller heat capacity jump, inconspicuous stiffness loss, insignificant structural change during glass transition, and a more depressed boson peak in the HE-MG than its counterpart. We accordingly propose a model to explain that a higher Sconf promotes a faster degeneracy-dependent kinetics for exploration of the potential energy landscape upon glass transition.

Microstructure Evolution and Mechanical Properties of Austenite Stainless Steel with Gradient Twinned Structure by Surface Mechanical Attrition Treatment.

Gradient structures in engineering materials produce an impressive synergy of strength and plasticity, thereafter, have recently attracted extensive attention in the material families. Gradient structured stainless steels (SS) were prepared by surface mechanical attrition treatment (SMAT) with different impacting velocities. The microstructures of the treated samples are characterized by gradient twin fraction and phase constituents. Quantitative relations of gradient microstructure with impacting time and mechanical properties are analyzed according to the observations of SEM, TEM, XRD, and tests of mechanical property. The processed SSs exhibited to be simultaneously stiff, strong, and ductile, which can be attributed to the co-operation of the different spatial distributions of multi-scaled structures. The formation of gradient twinned structure is resolved and the strengthening by gradient structure is explored.

Effects of nurse-led web-based interventions on people with type 2 diabetes mellitus: A systematic review and meta-analysis.

INTRODUCTION: Diabetes mellitus is an expanding global health problem. Currently, the home management of diabetes is mainly led by a multidisciplinary team based on telemedicine. However, the role nurses play in it remains inconclusive. This study aimed to investigate the effectiveness of nurse-led web-based intervention on glycated haemoglobin, blood pressure and lipid profile in patients with type 2 diabetes. METHODS: An exhaustive systematic literature search was undertaken using the following databases: PubMed, Web of Science, Embase, The Cochrane Central Register of Controlled Trials and CINAHL. Two investigators independently extracted data and assessed the quality of the studies by examining the risk of bias and using Modified Jadad Score system. We conducted a meta-analysis of randomized controlled trials that had been published from inception to July 2020, using Review Manager 5.3. RESULTS: Eleven randomized controlled trials were selected that included 2063 participants. Meta-analyses results indicated significant effects on not only glycated haemoglobin (pooled mean difference (MD) = -0.40, 95% confidence interval (CI): -0.5 to -0.26, p < 0.00001), but also on systolic blood pressure (pooled MD = -1.91, 95% CI: -3.73 to -0.09, p = 0.04) and low density lipoprotein (pooled standardized MD = -0.29, 95% CI: -0.44 to -0.15, p < 0.0001). There were no effects of nurse-led web-based intervention on fasting blood glucose, diastolic blood pressure, high density lipoprotein, body mass index and triglycerides. DISCUSSION: Nurse-led web-based intervention is a promising way to complement routine clinical care. However, the specific intervention content and intervention media still need to carry out large-scale well-designed randomized controlled trials. Systematic review registration: PROSPERO CRD 42020204565.

Impacts of frailty on health care costs among community-dwelling older adults: A meta-analysis of cohort studies.

BACKGROUND: The demands for health care services from the frail elderly individuals in the community continue to increase, which will exert a tremendous burden on health care costs. However, little is known regarding the magnitude of these impacts. In this study, we performed a systematic review and meta-analysis of the evidence to explore the impact of frailty on health care costs among community-dwelling older adults. MATERIALS AND METHODS: Relevant published articles were searched from PubMed, Embase, Web of Science, the Cochrane Library, China National Knowledge Infrastructure (CNKI), Chinese Science and Technology Journal Full-text Database (VIP), Wanfang Database, Chinese Biomedical Literature Database (CBM), and the reference lists of articles. Published cohort or cross-sectional studies assessing the impacts of frailty on health care costs among community-dwelling older adults were identified (to June 2020). The outcomes on health care costs before and after baseline were stratified by frailty status. RESULTS: A total of 7 cohort studies comprised of a total of 3,750,611 participants were included in our study. Our analyses showed that: (1) compared with the robust group, health care costs increased by $79-13,423.83 (standardized mean difference, SMD = 0.22, 95% Confidence interval, 95% CI, 0.22-0.22; P < 0.00001) in the pre-frail elderly and by $616-32,549.96 (SMD = 0.55, 95% CI, 0.44-0.67; P < 0.00001) in the frail elderly in the community. A significantly higher in the increase of health care costs was observed in the frail group compared with the pre-frail group(SMD = 0.35, 95% CI, 0.19-0.51; P < 0.0001); (2) the frailty phenotype components increased the health care costs of the elderly in community (weight loss: $1,630-6,209, SMD = 0.43, 95% CI, 0.17-0.69; P = 0.001; weakness: $275-7,586, SMD = 0.24, 95% CI, 0.08-0.40; P = 0.001; exhaustion: $1,545-10,559, SMD = 0.31, 95% CI, 0.13-0.49; P = 0.0006; slowness: $352-1,1891, SMD = 0.40, 95% CI = 0.14-0.65; P = 0.003; low physical activity: $512-3,459, SMD = 0.26, 95% CI, 0.16-0.36; P < 0.00001); (3) the increase in the frailty index was parallel with the increase in health care costs by $12,363-21,066 (SMD = 0.41, 95% CI, 0.29-0.53; P < 0.00001). CONCLUSIONS AND IMPLICATIONS: This study revealed the adverse economic impacts of frailty status, frailty phenotype components, and frailty index on health care costs in community-dwelling older adults. Future research is warranted to investigate costs incurred by interventions to improve frailty, which will provide further insights into additional health care costs due to frailty.

Associations between risk factors for cardiovascular diseases and frailty among community-dwelling older adults in Lanzhou, China.

OBJECTIVES: To examine the relationship between cardiovascular disease risk factors and frailty in a sample of older Chinese adults. METHODS: A total of 458 community-dwelling older adults (≥65 years) in Lanzhou, Gansu Province of China participated in a cross-sectional survey. Their status was evaluated in terms of frailty phenotype (unintentional weight loss, exhaustion, low activity levels, slowness and weakness). Participants were categorized as not frail, prefrail or frail. Cardiovascular disease risk factors that were assessed included: blood pressure, body mass index, waist circumference, blood glucose, total cholesterol, triglycerides, low-density lipoproteins and high-density lipoproteins. RESULTS: Individuals with obesity had an increased risk of prefrailty (OR: 2.26; 95% CI: 1.05, 4.84). Hypertension was inversely associated with frailty among the participants (OR: 0.31; 95% CI: 0.11, 0.87) after adjusting for covariates. CONCLUSIONS: The findings suggest that much more attention should be paid to weight control of the elderly in the community for preventing them from transition to prefrailty or frailty. Active prevention and control of cardiovascular diseases among the community-dwelling elder are still of great importance.

Modeling of an acoustically actuated artificial micro-swimmer.

Some recent achievements in microfabrication have demonstrated ultrasound-actuated artificial micro-swimmers for medical applications. However, the theoretical model of actuation and swimming is still lacking. Here we report a theoretical study of an acoustically actuated sperm-like artificial micro-swimmer which consists of a rigid head and a flexible flagellum. We provide the quantitative relation between head oscillation amplitude and acoustic pressure and frequency, and the theoretical account of how the flagellum is whipped, which brings about propulsion. The resistive force theory is employed in our model to relate the dynamic response of a flagellum and the motility of the swimmer. In order to make our theoretical model applicable in a realistic design of sperm-like micro-swimmer, we have involved the inertia term and material damping in the governing equation and considered the variable cross-section of a flagellum. The numerical results reveal that the micro-swimmer actuated by ultrasound can achieve a perceptible velocity, especially at resonance. Influences of non-dimensional parameters, such as the resonance index, sperm number, and material damping coefficient, are discussed and a comparison with experimental results demonstrates the validity of the proposed model.

Menopause and frailty: a scoping review.

IMPORTANCE AND OBJECTIVE: Frailty refers to the decline in physiological reserve capacity caused by the deterioration of multiple physiological systems (brain, endocrine system, immune system, and skeletal muscle), leading to increased vulnerability and decreased stress capacity. Women have a higher prevalence of frailty than men, although the epidemiological factors underlying this phenomenon are not fully understood. Menopause and menopause-related characteristics may be among the contributing factors. Hence, the purpose of this scoping review was to explore the relationship between menopause and frailty. We attempted to summarize information such as the age that menopause occurs, years since menopause, types of menopause, and hormones and inflammatory markers of frailty among postmenopausal women. METHODS: PubMed, EMBASE, The Cochrane Library, the Cumulative Index to Nursing and Allied Health Literature and Web of Science, the China National Knowledge Infrastructure, the China Biomedical Literature Service System, Wanfang Database and the WeiPu (VIP) Database were searched from inception until April 3, 2019. Supplementary searches of the references, cited documents, and similar documents of the included literature were also carried out. DISCUSSION AND CONCLUSIONS: Of 762 papers identified, 15 articles matching the criteria were included. The prevalence of frailty among postmenopausal women ranged from 5.9% to 57.3%. Existing studies suggest that menopause is associated with frailty. Early menopause, hysterectomy, low-free testosterone levels, and high C-reactive protein levels may increase the likelihood of frailty among postmenopausal women. Few original studies have explored the relationship between estrogen and frailty and the results of these studies are conflicting. Changes in hormone and inflammatory cytokine levels may mediate frailty among postmenopausal women. More in-depth research would be required to better understand the physiological and etiological mechanisms of the occurrence of frailty among postmenopausal women.

A promising new class of high-temperature alloys: eutectic high-entropy alloys.

High-entropy alloys (HEAs) can have either high strength or high ductility, and a simultaneous achievement of both still constitutes a tough challenge. The inferior castability and compositional segregation of HEAs are also obstacles for their technological applications. To tackle these problems, here we proposed a novel strategy to design HEAs using the eutectic alloy concept, i.e. to achieve a microstructure composed of alternating soft fcc and hard bcc phases. As a manifestation of this concept, an AlCoCrFeNi2.1 (atomic portion) eutectic high-entropy alloy (EHEA) was designed. The as-cast EHEA possessed a fine lamellar fcc/B2 microstructure, and showed an unprecedented combination of high tensile ductility and high fracture strength at room temperature. The excellent mechanical properties could be kept up to 700°C. This new alloy design strategy can be readily adapted to large-scale industrial production of HEAs with simultaneous high fracture strength and high ductility.