bluuebunny/crossref_metadata_2025 huggingface dataset:
China in transition towards a circular economy: from policy to practice
Authors: Zhao Yuhong
Published: September 2020

Purpose

The purpose of this paper is to examine China's approach to circular economy (CE) and investigate how the foreign concept of CE has been turned into a national strategy for implementation in production, circulation and consumption. This study aims to highlight the Chinese characteristics in the implementation of CE from central to local levels including the “trial and test” by pilot schemes and the role of local governments in CE transformation of industrial parks and in building CE cities. Based on what has been achieved, this paper aims to identify the gaps to be filled in the next stage of CE implementation.

Design/methodology/approach

This paper engages in critical analysis of state policies, plans, laws and regulations and case studies of Suzhou New District and Shanghai city in the building CE-oriented industrial park and CE city, respectively.

Findings

China has taken a top-down approach to CE characterised by strong government involvement in both policy and plan making and implementation at local levels. The government’s financial investment and administrative assistance proved to be crucial in the early stage of CE implementation to close the loop at industrial parks and in cities. In comparison, participation by enterprises and individuals is still weak and limited, which should be the focus of the next stage of CE implementation.

Originality/value

There is an absence of legal literature that studies circular economy in China. This paper fills the gap by examining the development of CE law and policy as well as CE implementation at local levels from industrial parks to cities.
Proactive policing in the United States: a national survey
Authors: Koper Christopher S. , Lum Cynthia , Wu Xiaoyun , Fritz Noah
Published: September 2020

Purpose

To measure the practice and management of proactive policing in local American police agencies and assess them in comparison to recommendations of the National Academies of Sciences (NAS) Committee on Proactive Policing.

Design/methodology/approach

A survey was conducted with a national sample of American police agencies having 100 or more sworn officers to obtain detailed information about the types of proactive work that officers engage in, to quantify their proactive work and to understand how the agencies measure and manage those activities. Responding agencies (n = 180) were geographically diverse and served populations of approximately half a million persons on average.

Findings

Proactivity as practiced is much more limited in scope than what the NAS envisions. Most agencies track only a few forms of proactivity and cannot readily estimate how much uncommitted time officers have available for proactive work. Measured proactivity is mostly limited to traffic stops, business and property checks and some form of directed or general preventive patrol. Many agencies have no formal policy in place to define or guide proactive activities, nor do they evaluate officer performance on proactivity with a detailed and deliberate rubric.

Originality/value

This is the first national survey that attempts to quantify proactive policing as practiced broadly in the United States. It provides context to the NAS recommendations and provides knowledge about the gap between practice and those recommendations.
Diagnostic accuracy of 14‐3‐3 η protein in rheumatoid arthritis: A meta‐analysis
Authors: Wang Decai , Cui Yalan , Lei Huiren , Cao Ding , Tang Guoting , Huang Haiming , Yuan Ting , Rao Lizong , Mo Biwen
Published: September 2020

Aim

To evaluate the overall diagnostic performance of 14‐3‐3 η protein in patients with rheumatoid arthritis (RA).

Methods

PubMed, EMBASE, and Web of Science were searched to acquire eligible studies. Articles published in English before 20 February 2020 were included. Quality Assessment of Diagnostic Accuracy Studies 2 was used to evaluate the risk of bias and application concern of the included articles. Pooled analysis of diagnostic indicators of 14‐3‐3 η protein for RA was conducted by using a random effects model. Subgroup analysis was used to explore the sources of heterogeneity. Deeks' funnel plot asymmetry test was used to evaluate for the presence of publication bias.

Results

A total of 13 studies (1554 positive and 1934 negative participants) were included. The pooled sensitivity and specificity were 0.73 (95% CI 0.71‐0.75) and 0.88 (95% CI 0.87‐0.90), respectively. The pooled positive/negative likelihood were 5.98 (95% CI 4.39‐8.14) and 0.28 (95% CI 0.21‐0.37), respectively. In addition, the pooled diagnostic odds ratio was 23.48 (95% CI 13.76‐40.08) and the area under curve was 0.9245. The results of subgroup analysis indicated that ethnicity and control group might be the source of heterogeneity. The results of sensitivity analysis were stable. No significant publication bias was found.

Conclusions

The current evidence indicated that 14‐3‐3 η protein has moderate accuracy for the diagnosis of RA.
Comorbidity, not patient age, is associated with impaired safety outcomes in vedolizumab‐ and ustekinumab‐treated patients with inflammatory bowel disease—a prospective multicentre cohort study
Authors: Asscher Vera E. R. , Biemans Vince B. C. , Pierik Marieke J. , Dijkstra Gerard , Löwenberg Mark , van der Marel Sander , de Boer Nanne K. H. , Bodelier Alexander G. L. , Jansen Jeroen M. , West Rachel L. , Haans Jeoffrey J. L. , van Dop Willemijn A. , Weersma Rinse K. , Hoentjen Frank , Maljaars P. W. Jeroen ,   the Dutch Initiative on Crohn and Colitis (ICC)
Published: September 2020

Background

Few data are available on the effects of age and comorbidity on treatment outcomes of vedolizumab and ustekinumab in inflammatory bowel disease (IBD).

Aims

To evaluate the association between age and comorbidity with safety and effectiveness outcomes of vedolizumab and ustekinumab in IBD.

Methods

IBD patients initiating vedolizumab or ustekinumab in regular care were enrolled prospectively. Comorbidity prevalence was assessed using the Charlson Comorbidity Index (CCI). Association between age and CCI, both continuously assessed, with safety outcomes (any infection, hospitalisation, adverse events) during treatment, and effectiveness outcomes (clinical response and remission, corticosteroid‐free remission, clinical remission combined with biochemical remission) after 52 weeks of treatment were evaluated. Multivariable logistic regression was used to adjust for confounders.

Results

We included 203 vedolizumab‐ and 207 ustekinumab‐treated IBD patients, mean age 42.2 (SD 16.0) and 41.6 (SD 14.4). Median treatment duration 54.0 (IQR 19.9‐104.0) and 48.4 (IQR 24.4‐55.1) weeks, median follow‐up time 104.0 (IQR 103.1‐104.0) and 52.0 weeks (IQR 49.3‐100.4). On vedolizumab, CCI associated independently with any infection (OR 1.387, 95% CI 1.022‐1.883, P = 0.036) and hospitalisation (OR 1.586, 95% CI 1.127‐2.231, P = 0.008). On ustekinumab, CCI associated independently with hospitalisation (OR 1.621, 95% CI 1.034‐2.541, P = 0.035). CCI was not associated with effectiveness, and age was not associated with any outcomes.

Conclusions

Comorbidity ‐ but not age ‐ is associated with an increased risk of hospitalisations on either treatment, and with any infection on vedolizumab. This underlines the importance of comorbidity assessment and safety monitoring of IBD patients.
A long non‐coding RNA (Lrap) modulates brain gene expression and levels of alcohol consumption in rats
Authors: Saba Laura M. , Hoffman Paula L. , Homanics Gregg E. , Mahaffey Spencer , Daulatabad Swapna Vidhur , Janga Sarath Chandra , Tabakoff Boris
Published: September 2020

LncRNAs are important regulators of quantitative and qualitative features of the transcriptome. We have used QTL and other statistical analyses to identify a gene coexpression module associated with alcohol consumption. The “hub gene” of this module, Lrap (Long non‐coding RNA for alcohol preference), was an unannotated transcript resembling a lncRNA. We used partial correlation analyses to establish that Lrap is a major contributor to the integrity of the coexpression module. Using CRISPR/Cas9 technology, we disrupted an exon of Lrap in Wistar rats. Measures of alcohol consumption in wild type, heterozygous and knockout rats showed that disruption of Lrap produced increases in alcohol consumption/alcohol preference. The disruption of Lrap also produced changes in expression of over 700 other transcripts. Furthermore, it became apparent that Lrap may have a function in alternative splicing of the affected transcripts. The GO category of “Response to Ethanol” emerged as one of the top candidates in an enrichment analysis of the differentially expressed transcripts. We validate the role of Lrap as a mediator of alcohol consumption by rats, and also implicate Lrap as a modifier of the expression and splicing of a large number of brain transcripts. A defined subset of these transcripts significantly impacts alcohol consumption by rats (and possibly humans). Our work shows the pleiotropic nature of non‐coding elements of the genome, the power of network analysis in identifying the critical elements influencing phenotypes, and the fact that not all changes produced by genetic editing are critical for the concomitant changes in phenotype.
High silicon concentrations in grasses are linked to environmental conditions and not associated with C4 photosynthesis
Authors: Brightly William H. , Hartley Sue E. , Osborne Colin P. , Simpson Kimberley J. , Strömberg Caroline A. E.
Published: September 2020

The uptake and deposition of silicon (Si) as silica phytoliths is common among land plants and is associated with a variety of functions. Among these, herbivore defense has received significant attention, particularly with regard to grasses and grasslands. Grasses are well known for their high silica content, a trait which has important implications ranging from defense to global Si cycling. Here, we test the classic hypothesis that C4 grasses evolved stronger mechanical defenses than C3 grasses through increased phytolith deposition, in response to extensive ungulate herbivory (“C4‐grazer hypothesis”). Despite mixed support, this hypothesis has received broad attention, even outside the realm of plant biology. Because C3 and C4 grasses typically dominate in different climates, with the latter more abundant in hot, dry regions, we also investigated the effects of water availability and temperature on Si deposition. We compiled a large dataset of grasses grown under controlled environmental conditions. Using phylogenetically informed generalized linear mixed models and character evolution models, we evaluated whether photosynthetic pathway or growth condition influenced Si concentration. We found that C4 grasses did not show consistently elevated Si concentrations compared with C3 grasses. High temperature treatments were associated with increased concentration, especially in taxa adapted to warm regions. Although the effect was less pronounced, reduced water treatment also promoted silica deposition, with slightly stronger response in dry habitat species. The evidence presented here rejects the “C4‐grazer hypothesis.” Instead, we propose that the tendency for C4 grasses to outcompete C3 species under hot, dry conditions explains previous observations supporting this hypothesis. These findings also suggest a mechanism via which anthropogenic climate change may influence silica deposition in grasses and, by extension, alter the important ecological and geochemical processes it affects.
High‐density mapping validation of antral pulmonary vein isolation and posterior wall isolation created with a new cryoballoon ablation system: The first reported case
Authors: Moltrasio Massimo , Kochi Adriano N. , Fassini Gaetano , Riva Stefania , Tundo Fabrizio , Tondo Claudio
Published: September 2020

Cryoballoon ablation is a recognized and widespread method for pulmonary vein isolation. For many years the impossibility of using it to create additional lines was considered a drawback of this approach. However, recently, the technique was adapted to allow the creation of rooflines, and potentially also inferior lines. In this article, we present the first reported case of a patient submitted to pulmonary vein isolation plus posterior wall isolation using the novel Boston POLAR X™ cryoballoon exclusively. To confirm the quality of the lesions, the patient underwent pre and postablation high‐density mapping.
Investigations on the process and product parameters of radio frequency‐induced accelerated aged paddy
Authors: Iftikhar Farheena , Hussain Syed Zameer , Naseer Bazila , Nidoni Uday Kumar , Naik Haroon R.
Published: September 2020

The present study was conducted with an aim to reduce the aging time of paddy through the application of radio frequency (RF) heating. The effects of paddy moisture content and RF exposure time on various quality attributes of rice were investigated using response surface methodology. Both moisture content and RF exposure time were set at five levels between 11–21.5% and 17–208 min, respectively. The process variables significantly affected all the quality parameters except kernel elongation ratio, non‐reducing sugars, trough viscosity, hardness, and stickiness. Models obtained for these parameters were highly significant (p ≤ .0027) with high coefficient of determination (R2 ≥ .893). Optimum conditions to induce accelerated aging in paddy using RF heating were 45 min of RF exposure time at 16.3% moisture content of paddy. The outcome of the study could be very useful for researchers in future to plan in depth studies on accelerated aging of paddy through RF heating.

Practical Applications

Freshly harvested rice is less preferred by consumers because of its poor cooking properties. However, natural aging takes a long time to induce desirable quality changes in rice, while accelerating aging improves the quality of rice more rapidly. However, all the accelerated aging methods reported so far have many limitations such as restricted penetration power, lower efficiency, and slow heating. Radio frequency (RF) heating is undoubtedly superior to all such heating methods due to its deeper penetration power, faster heating, and suitability to process bulk materials. The outcome of this study in terms of predictive models and optimized conditions of RF exposure time and moisture content, if properly manipulated can help to induce desirable quality changes in rice within the shortest period of time. Inference drawn from the present study was that the RF heating can emerge as a novel approach to induce accelerating aging in rice.
Integrating Digital Technology in an Intensive, Fully Online College Course for Japanese Beginning Learners: A Standards‐Based, Performance‐Driven Approach
Authors: SATO ERIKO , CHEN JULIAN CHENG CHIANG , JOURDAIN SARAH
Published: September 2020

The development of distance learning courses for less commonly taught languages (LCTLs) often meets with instructional challenges, especially for Asian LCTLs with their distinct non‐Roman characters and structures. This study documents the implementation of a fully online, elementary Japanese course at Stony Brook University. The curriculum was designed around the American Council on the Teaching of Foreign Languages's (ACTFL) World‐Readiness Standards for Learning Languages; performance‐driven assessments; and task‐supported, technology‐enhanced principles. Asynchronous and synchronous tools were incorporated to facilitate task delivery and reduce the virtual isolation of learners. A simulated Oral Proficiency Interview (OPI) was conducted for the online students in order to compare their oral performance with that of the face‐to‐face (F2F) cohort in the preceding semester. Quantitative results show that online students outperformed their F2F counterparts in most of the Integrated Performance Assessment's scoring criteria, with a statistically significant difference in the criterion “Communication strategies.” Survey results indicate students’ positive attitudes toward language gains and corroborate the qualitative results gleaned from student learning journals and survey responses: Students’ sense of isolation was replaced by a sense of co‐presence. We conclude that developing an online LCTL course, though challenging, is feasible and maximizes outcomes through the synergy of multimodal digital platforms, and a standards‐based, task‐driven curriculum design.
Equivalent Linearization of Bladed Disk Assemblies With Friction Nonlinearities Under Random Excitation
Authors: Förster Alwin , Panning-von Scheidt Lars , Wallaschek Jörg
Published: September 2020

This article addresses the vibrational behavior of bladed disk assemblies with nonlinear shroud coupling under random excitation. In order to increase the service life and safety of turbine blades, intense calculations are carried out to predict the vibrational behavior. The use of friction dampers for energy dissipation and suppression of large amplitudes makes the mechanical system nonlinear, which complicates the calculations. Depending on the stage, different types of excitation can occur in a turbine, from clearly defined deterministic to random excitation. So far, the latter problem has only been dealt with to a limited extent in the literature on turbomachinery. Nevertheless, there are in general different approaches and methods to address this problem most of which are strongly restricted with regard to the number of degrees-of-freedom (DOF). The focus of this paper is the application of an equivalent linearization method (ELM) to calculate the stochastic response of an academic model of a bladed disk assembly under random excitation. The nonlinear contact is modeled both with an elastic Coulomb-slider and a Bouc–Wen formulation to reproduce the hysteretic character of a friction nonlinearity occurring in the presence of a friction damper. Both the excitation and the response are limited to mean-free, stationary stochastic processes, which means that the stochastic moments do not change over time. Unlike previous papers on this topic, the calculations are performed on a full bladed disk assembly in which each segment is approximated with several degrees-of-freedom.
Mining Design Heuristics for Additive Manufacturing Via Eye-Tracking Methods and Hidden Markov Modeling
Authors: Mehta Priyesh , Malviya Manoj , McComb Christopher , Manogharan Guha , Berdanier Catherine G. P.
Published: September 2020

In this research, we collected eye-tracking data from nine engineering graduate students as they redesigned a traditionally manufactured part for additive manufacturing (AM). Final artifacts were assessed for manufacturability and quality of final design, and design behaviors were captured via the eye-tracking data. Statistical analysis of design behavior duration shows that participants with more than 3 years of industry experience spend significantly less time removing material and revising than those with less experience. Hidden Markov modeling (HMM) analysis of the design behaviors gives insight to the transitions between behaviors through which designers proceed. Findings show that high-performing designers proceeded through four behavioral states, smoothly transitioning between states. In contrast, low-performing designers roughly transitioned between states, with moderate transition probabilities back and forth between multiple states.
Assembly Variation Analysis of Incompletely Positioned Macpherson Suspension Systems Considering Vehicle Load Change
Authors: Niu Zhihua , Jin Sun , Li Zhimin
Published: September 2020

The assembly precision of wheel alignment parameters is vital to vehicle handling stability. Due to the vertical wheel displacement and compliant components in suspension systems, it is difficult to assemble qualified vehicles with proper wheel alignment parameters. In the assembly shop of the automobile factory, the adjustment of wheel alignment parameters is the most time-consuming process because it relies on trial and error. In order to provide a theoretical guidance to the precision control of wheel alignment parameters, this paper extends the theory of equilibrium equations of incremental forces (EEIF) to 3D compliant mechanisms. Constraint equations of kinematic joints are adopted to express the spatial relationships of different parts. A couple of fixed and floating joint coordinate systems (CSs) are used together to represent deviations of compliant components. The impacts of suspension part deviations on vertical wheel displacement and assembly deformations are well illustrated by such approach. Accuracy of the proposed method is verified by comparing with ADAMS simulation. The results show that the error rates of the 3D EEIF method are less than 5%. Furthermore, statistical assembly variation analysis of a Macpherson suspension is accomplished by using the proposed method and an optimized process strategy is put forward.
A Simplified Analytical Model for Estimation of the Initial Waterhammer Pressure and Force on a Circular Tube
Authors: Jo Jong Chull , Jeong Jae Jun , Moody Frederick J.
Published: September 2020

A simplified analytical model is developed for estimating the initial waterhammer pressure and force on a circular tube when a plane decompression wave, parallel to its axis, passes over it. The simplified analysis superimposes the solutions for a plane pressure wave traveling at sound speed in the surrounding water, and two-dimensional solution to the wave equation in cylindrical coordinates, with a nonflow boundary condition across the tube boundary at a fixed radius. The analytical method is compared to the computational fluid dynamics (CFD) approach by applying to predict the initial waterhammer pressure and force on the closest tube to the feedwater nozzle of a geometrically simplified nuclear steam generator (SG) analysis model, caused by a feedwater pipe break (FWPB). As the result, it is found that the simplified analytical model, while not matching results of the CFD calculations with precise accuracy, does confirm the nature of the waterhammer impact pressure loads on the SG tubes.
An Image-Based Approach to Variational Path Synthesis of Linkages
Authors: Deshpande Shrinath , Purwar Anurag
Published: September 2020

This paper brings together computer vision, mechanism synthesis, and machine learning to create an image-based variational path synthesis approach for linkage mechanisms. An image-based approach is particularly amenable to mechanism synthesis when the input from mechanism designers is deliberately imprecise or inherently uncertain due to the nature of the problem. In addition, it also lends itself naturally to the creation of a unified approach to mechanism synthesis for different types of mechanisms, since for example, images are formed from a collection of pixels, which themselves could be generated from a four-bar or six-bar. Path synthesis problems have generally been solved for a set of precision points on the intended path such that the designed mechanism passes through those points. This approach usually leads to a small set of over-fitted solutions to particular precision points. However, most kinematic synthesis problems are concept generation problems, where a designer cares more about generating a large number of plausible solutions, which could reach given precision points only approximately. This paper models the input curve as a probability distribution of image pixels and employs a probabilistic generative model to capture the inherent uncertainty in the input. In addition, it gives feedback on the input quality and provides corrections for a more conducive input. The image representation allows for capturing local spatial correlations, which plays an important role in finding a variety of solutions with similar semantics as the input curve. This approach is also conducive to implementation for pressure-sensitive touch-based design interfaces, where the input is not a zero-thickness curve, but the sweep of a small patch on the finger.
Relation Between Neck Skin Temperature Measurement and Carotid Artery Stenosis: In-Vitro Evaluation
Authors: Saxena Ashish , Ng Eddie Yin Kwee , Canchi Tejas , Tee Jun Jie , Ng Lip Koon
Published: September 2020

Carotid artery stenosis is a form of atherosclerosis, where thrombus formation restricts the passage of blood through the carotid artery leading to irreversible damage in the brain tissue. The presence of stenosis in the carotid artery results in abnormal temperature maps on the external skin surface, which can be captured and quantified using noncontact/noninvasive infrared (IR) thermal imaging/thermography. In this study, a thermally charged in vitro carotid artery flow loop, using 0% and 75% stenosis models, was designed to study the thermal effect on the external skin surface. The carotid artery flow was encapsulated with polydimethylsiloxane (PDMS) resembling neck tissue, of which the external surface temperature maps were studied using IR thermography. Using the mean temperature as a threshold value, the resultant thermal image was processed and normalized. Between the two stenosis models, disruption in the thermal features corresponding to the presence of stenosis was observed. The method described in this study paves the path to experimentally study the thermal effect of the presence of stenosis in the carotid artery.
Gateway Configuration for Rapid Pick-and-Place Operations of 2-Degrees-of-Freedom Parallel Robots
Authors: Martin-Parra Andrea , Rodriguez-Rosa David , Juarez-Perez Sergio , Rubio-Gomez Guillermo , Gonzalez-Rodriguez Antonio , Castillo-Garcia Fernando J.
Published: September 2020

This article presents a new assembling for 2 degrees-of-freedom (DOFs) parallel robots for executing rapid pick-and-place operations with low energy consumption. A conventional design of 2-DOF parallel robots is based on five-bar mechanisms. Collisions between links are highly possible, restricting the end-effector workspace and/or increasing the trajectory time to avoid collisions. In this article, an alternative assembling for preventing collisions is presented. This novel assembling allows exploring the difference between the four five-bar mechanism configurations for the same position of the end-effector. Some of these configurations yield to lower time and/or lower energy consumption for the same motorization. First, a dynamic model of the robot has been developed using matlab® and simulink® and validated by comparison with the results obtained by adams® software. A robust cascade PD regulator for controlling joint coordinates has been tuned providing a high accurate end-effector positioning. Finally, simulation results of four configurations are presented for executing controlled maneuvers. The obtained results demonstrate that the conventional configuration is the worst one in terms of trajectory time or energy consumption and, conversely, the best one corresponds to an uncommonly used configuration. A workspace map where all configurations provide faster maneuvers has been obtained in terms of Jacobian matrix and mechanism elbows distance. The results presented here allow designing a rapid manipulator for pick-and-place operations.
Cosine Error-Free Metrology Tool Path Planning for Thickness Profile Measurements
Authors: Guo Xiangyu , Lee ChaBum
Published: September 2020

This paper presents a novel thickness profile measuring system that measures double-sided thin pipe wall surfaces in a non-contact, continuous, cosine error-free, and fast manner. The surface metrology tool path was developed to align the displacement sensors always normal to the double-sided surfaces to remove cosine error. A pair of capacitive-type sensors that were placed on the rotary and linear axes simultaneously scans the inner and outer surfaces of thin walls. Because the rotational error of the rotary axis can severely affect the accuracy in thickness profile measurement, such error was initially characterized by a reversal method. It was compensated for along the rotational direction while measuring the measurement target. Two measurement targets (circular and elliptical metal pipe-type thin walls) were prepared to validate the developed measurement method and system. Not only inner and outer surface profiles but also thin-wall thickness profiles were measured simultaneously. Based on the output data, the circularity and wall thickness variation were calculated. The thickness profile results showed a good agreement with those obtained by a contact-type micrometer (1-µm resolution) at every 6-deg interval. The uncertainty budget for this measuring system with metrology tool path planning was estimated at approximately 1.4 µm.
Gas Labyrinth Seals: Improved Prediction of Leakage in Gas Labyrinth Seals Using an Updated Kinetic Energy Carry-Over Coefficient
Authors: Wu Tingcheng , Andrés Luis San
Published: September 2020

Though simple and fast, bulk-flow models (BFMs) for gas labyrinth seals (LSs) often predict the mass flow inaccurately. The BFM models rely on classical Neumann's equation model to characterize the flow through a labyrinth tooth. Presently, a computational fluid dynamics (CFD) analysis quantifies the effects of tip clearance (Cr) and operating conditions on the prediction of LS mass flow, and then derives an updated kinetic energy carry-over coefficient (μ1i) to improve the accuracy of Neumann's leakage equation. μ1i is a function of the seal tip clearance (Cr), the tooth pitch, and the total teeth number; but it does not depend on the seal supply or discharge pressures. The analysis selects a 14-teeth on stator LS (length/diameter = L/D = 0.29) with clearance Cr = (1/733)D and operating at nominal supply (Pin) and discharge (Pout) pressures equal to 73 bar and 51 bar, respectively, and at a rotor speed of 12 krpm (surface speed = 138 m/s). The CFD produces flow fields for LSs with a clearance varying from 80% to 200% of the nominal Cr, a gas supply pressure from 60 bar to 100 bar, and with various discharge pressures giving a pressure ratio (PR = Pout/Pin) ranging from 0.40 to 0.85. The numerous predictions deliver the mass flow as well as the bulk-flow velocities and cavity pressures within the seals. The kinetic energy carry-over coefficient (μ1i) increases with respect to the seal radial clearance (Cr). μ1i shows a parabolic correlation with PR; at first, μ1i increases with a rise in PR from a low value; and then, a further increase in PR leads to a decrease in μ1i. The coefficient μ1i is only sensitive to the PR and not to the magnitude of either the supply or discharge pressures. Lastly, for use with Neumann's leakage model, the CFD predictions produce an updated μ1i, a function of the seal geometry and the PR condition. Integration of the new μ1i correlation into a BFM code improves its accuracy to predict LS mass flow rate, a 19% difference against test data reduces to within 6%. A TOS LS tested by Ertas et al. (2012, Rotordynamic Force Coefficients for Three Types of Annular Gas Seals With Inlet Preswirl and High Differential Pressure Ratio,” ASME J. Eng. Gas Turbine Power, 134(4), p. 4250301) serves to further validate the accuracy of the modified leakage model.
The Environmental Impacts of Metal Powder Bed Additive Manufacturing
Authors: Liao Jiankan , Cooper Daniel R.
Published: September 2020

Additive manufacturing (AM) is widely recognized as a critical pillar of advanced manufacturing and is moving from the design shop to the factory floor. As AM processes become more popular, it is paramount that engineers and policymakers understand and then reduce their environmental impacts. This article structures the current work on the environmental impacts of metal powder bed processes: selective laser melting (SLM), direct metal laser sintering (DMLS), electron beam melting (EBM), and binder jetting (BJ). We review the potential benefits and pitfalls of AM in each phase of a part's lifecycle and in different application domains (e.g., remanufacturing and hybrid manufacturing). We highlight critical uncertainties and future research directions throughout. The environmental impacts of AM are sensitive to the specific production and use-phase context; however, several broad lessons can be extracted from the literature. Unlike in conventional manufacturing, powder bed production impacts are dominated by the generation of the direct energy (electricity) required to operate the AM machines. Combined with a more energy-intensive feedstock (metal powder), this means that powder bed production impacts are higher than in conventional manufacturing unless production volumes are very small (saving tool production impacts), and/or there are significant material savings through part light weighting or improved buy-to-fly ratios.
Expulsion Intensity Monitoring and Modeling in Resistance Spot Welding Based on Electrode Displacement Signals
Authors: Xia Yu-Jun , Shen Yan , Zhou Lang , Li Yong-Bing
Published: September 2020

Weld expulsion is one of the most common welding defects during the resistance spot welding (RSW) process, especially for high strength steels (HSS). In order to control and eventually eliminate weld expulsion in production, accurate assessment of the expulsion severity should be the first step and is urgently required. Among the existing methods, real-time monitoring of RSW-related process signals has become a promising approach to actualize the online evaluation of weld expulsion. However, the inherent correlation between the process signals and the expulsion intensity is still unclear. In this work, a commonly used process signal, namely, the electrode displacement and its instantaneous behavior when expulsion occurs are systematically studied. Based upon experiments with various electrodes and workpieces, a nonlinear correlation between the weight of expelled metal and the sudden displacement drop accompanied by the occurrence of weld expulsion is observed, which is mainly influenced by electrode tip geometry but not by material strength or sheet thickness. The intrinsic relationship between this specific signal feature and the magnitude of expulsion is further explored through geometrical analysis, and a modified analytical model for online expulsion evaluation is finally proposed. It is shown that the improved model could be applied to domed electrodes with different tip geometries and varying workpieces ranging from low carbon steel to HSS. The error of expulsion estimation could be limited within ±20.4 mg (±2σ) at a 95% confidence level. This study may contribute to the online control of weld expulsion to the minimum level.
3D Printing of Flexible and Stretchable Parts Using Multiwall Carbon Nanotube/Polyester-Based Thermoplastic Polyurethane
Authors: Stan Felicia , Stanciu Nicoleta-Violeta , Constantinescu Adriana-Madalina , Fetecau Catalin
Published: September 2020

This paper reports on the 3D printing of flexible and stretchable parts based on multiwall carbon nanotube (MWCNT)/polyester-based thermoplastic polyurethane (TPU) nanocomposites. The rheological properties of the WCNT/TPU nanocomposites with different wt% of MWCNTs (0.1–3) were determined and used as guidance for the extrusion and 3D printing processes. MWCNT/TPU filaments were extruded and used for 3D printing of different flexible and stretchable parts. The mechanical, electrical, and piezoresistive response of the MWCNT/TPU nanocomposite filaments and 3D printed parts under static and monotonic loading was studied. The experimental results show that with increasing temperature and shear rate, respectively, the shear viscosity of the MWCNT/TPU nanocomposite decreases, whereas the viscosity increases with increasing wt% of MWCNTs. With the addition of MWCNTs, the elastic modulus and tensile strength of the feedstock filament all increase, enhancing the printability of TPU by increasing the buckling resistance and the stability of the 3D printed layer. The electrical conductivity of the 3D printed MWCNT/TPU nanocomposites increases with increasing wt% of MWCNTs and exceeds the conductivity of the filaments. The 3D printed MWCNT/TPU nanocomposites with 3 wt% show an electrical conductivity about 10 S/m, irrespective of the printing direction. Moreover, the 3D printed MWCNT/TPU nanocomposites exhibit good mechanical properties and high piezoresistive sensitivity with gauge factor (50–600) dependent on both strain and printing direction.
A Vibration-Assisted Separation Method for Constrained-Surface-Based Stereolithography
Authors: Xu Yang , Zhu Yizhen , Sun Yifeng , Jin Jie , Chen Yong
Published: September 2020

For the bottom-up based stereolithography (SL) process, a separation process is required to detach the newly cured layer from the constrained surface in the fabrication process. Excessive separation force will cause damage to the built layers and the constrained surface. Different surface coatings, platform motions including tilting and sliding, and the utilization of oxygen-permeable films have been developed to address the separation-related problems. Among these approaches, the vibration-assisted (VA) separation method to reduce the separation force has limited study. The underlying mechanism of the VA separation-based method remains unexplored, and the best way to use VA separation in the bottom-up based SL process is still unclear. In this paper, a new VA separation design for the SL process is presented. A prototype system was built to study the VA separation mechanism. Experiments on the separation performance under different parameters, including vibration frequency, pre-stress level, and exposure area, were conducted. Based on the collected separation force data, an analytical model based on the mechanics of fatigue fracture was built. The separation behaviors related to different shape size and topology were also studied and compared. The results showed that the separation force in SL was significantly reduced using the VA separation-based method. Furthermore, the relationship between the separation force and the separation time conforms to the stress-based fatigue model. This study also provides insights on how to choose process parameters by considering the trade-offs between separation force and building efficiency.
Carbon content control of silicon oxycarbide film with methane containing plasma
Authors: Song Seokhwi , Park Suhyeon , Jung Chanwon , Park Hyunwoo , Kim Youngjoon , Jeon Hyeongtag
Published: September 2020

Deposition of silicon oxycarbide (SiCOH) thin films by remote plasma atomic layer deposition was performed. In the experiment, the recipe was composed by adjusting the ratio of Ar and CH4 plasmas to control the carbon content in the SiCOH thin film. Octamethyl cyclotetrasiloxane was used as a precursor during the deposition process at 200, 300, and 400 °C. Ar plasma was used as an activant and CH4 plasma was used as a reactant. Plasma and deposition temperatures cause a significant impact on the physical and electrical properties of the film. When CH4 plasma was used during the deposition process, the film contained carbon and exhibited a low dielectric constant. In addition, when CH4 plasma is used as a reactant, Si–C bonds in the thin film form pores and lower ionic polarization to lower the dielectric constant. Fourier-transform infrared spectroscopy data indicate that the higher the ratio of CH4 plasma, the more the cage structure in the thin film. The cage structure contributes to lowering the dielectric constant of the thin film. The film deposited with Ar plasma has the dielectric constant of 3.2 and the film deposited with CH4 plasma has the dielectric constant of 2.6. In both plasma conditions, the dielectric constant was lower than the SiO2 film with the dielectric constant of 3.9. On the other hand, x-ray photoelectron spectroscopy analysis showed that SiO1–C3 and SiC4 bonds appeared in the film deposited with CH4 plasma, which did not appear in the film deposited with Ar plasma. These bonds affected the physical and electrical properties of the thin film.
Structure of soft and hard protein corona around polystyrene nanoplastics—Particle size and protein types
Authors: Kihara Shinji , Ghosh Sunandita , McDougall Daniel R. , Whitten Andrew E. , Mata Jitendra P. , Köper Ingo , McGillivray Duncan J.
Published: September 2020

A major challenge in understanding nanoplastic toxicity (or nanoparticles in general) lies in establishing the causal relationships between its physical properties and biological impact. This difficulty can be attributed to surface alterations that follow the formation of a biological complex around the nanoplastic, as exemplified by protein coronae. The protein corona is known to be responsible for the biological response elicited, although its own structure and attributes remain unknown. We approach this knowledge gap by independently studying the structure of soft and hard coronae using neutron scattering techniques. We investigated the formation and the structure of corona proteins (human serum albumin and lysozyme) and the resulting protein corona complexes with polystyrene nanoplastics of different sizes (20 and 200 nm) and charges. Soft corona complexes (regardless of protein type) adopted a structure where the nanoplastics were surrounded by a loose protein layer (∼2–3 protein molecules thick). Hard corona complexes formed fractal-like aggregates, and the morphology of which is known to be harmful to cellular membranes. In most cases, hard-corona coated nanoplastics also formed fractal-like aggregates in solution. Nanoplastic size affected the structures of both the protein corona and the intrinsic protein: more significant conformational change was observed in the hard corona proteins around smaller nanoparticles compared to larger ones, as the self-association forces holding the nanoplastic/protein complex together were stronger. This also implies that protein-dependent biochemical processes are more likely to be disrupted by smaller polystyrene nanoplastics, rather than larger ones.
Sample handling, preparation and mounting for XPS and other surface analytical techniques
Authors: Stevie Fred A. , Garcia Roberto , Shallenberger Jeffrey , Newman John G. , Donley Carrie L.
Published: September 2020

Sample preparation and mounting are important aspects of x-ray photoelectron spectroscopy (XPS) analysis. New users do not know many techniques that are familiar to analysts with years of experience, and these observations and “tricks of the trade” are typically not published. This article is intended to convey the experience of the authors in this field who have creatively analyzed a wide range of samples. Samples can include solids, powders, fibers, porous solids, and even liquids. This information is also important to anyone submitting samples for analysis, since the preparation of the sample may influence the usefulness of the data collected. These techniques are also applicable to other surface analysis methods.
The Relationship Between Resilience and Self-Reported Function in Patients After Total Joint Arthroplasty: A Critically Appraised Topic
Authors: Swann Ansley E. , Kleis Rachel R. , Hoch Johanna M.
Published: September 2020

Clinical Question: Is there a relationship between resilience and self-reported function in patients who underwent a total joint arthroplasty? Clinical Bottom Line: There is inconsistent, good-quality Level II evidence that investigates the relationship between resilience and self-reported function in patients after joint arthroplasty.
Ankle Support Beliefs of High School Basketball Coaches and the Ankle Support Practices of their Athletes
Authors: Rudnick Miranda , Wallace Brian
Published: September 2020

Ankle supports have been shown to reduce ankle injury incidence. Athletes’ use of them may be related to their sport coaches’ beliefs. The purpose of this study was to examine Wisconsin high school boys’ and girls’ basketball coaches’ beliefs regarding ankle support practices. Additional aims were to estimate the percentage of the players who either tape or brace, reveal which sources were used to form coaches’ beliefs about ankle supports, and gain insights regarding how long players are out of play after being injured if they tape, brace, or do not use ankle supports. Chi-squared tests of independence revealed that most coaches neither encouraged nor discouraged ankle supports for their players. A majority of coaches were found to use resources other than scientific-based sources to form their opinions on ankle supports. They also reported that they believed ankle injury return-to-play time was reduced in players who wore ankle supports and that supports did not hinder performance. Coaches should be provided educational opportunities regarding ankle supports so they may provide valid information to help their players make informed decisions.
Upper Limb Proprioceptive Acuity Assessment Based on Three-Dimensional Position Measurement Systems
Authors: Li Lin , Li Yanxia , Wu Chang-hong , Fu Hao
Published: September 2020

The aim of the current work was to verify three-dimensional directional effects on the reproduction error precision of the human upper limb position. Thirty male subjects without history of upper limb pathology were recruited from Renmin University of China. A three-dimensional position reproduction task in six directions (up, down, left, right, far, and near) was performed by each subject. The results suggested that the proprioceptive sense of upper limb position depends on the direction, with smaller absolute errors in Directions 4 (right) and 5 (far) than in Directions 1 (up), 2 (down), 3 (left), and 6 (near). Proprioception near the end of the elbow joint range of motion may be more reliable and sensitive. Subjects reproduced fewer ranges in the horizontal plane (Directions 3, 5, and 6) and they overshot the target position along the z-axis (vertical direction) except for Direction 6. Overestimations of position in the z-axis may be caused by overestimations of force.
The Heterotrophic Bacterium Cupriavidus pinatubonensis JMP134 Oxidizes Sulfide to Sulfate with Thiosulfate as a Key Intermediate
Authors: Xin Yufeng , Gao Rui , Cui Feifei , Lü Chuanjuan , Liu Honglei , Liu Huaiwei , Xia Yongzhen , Xun Luying
Published: September 2020

We establish a new pathway of sulfide oxidation with thiosulfate as a key intermediate in
Cupriavidus pinatubonensis
JMP134. The bacterium mainly oxidizes sulfide by using sulfide:quinone oxidoreductase, persulfide dioxygenase, and the Sox system with thiosulfate as a key intermediate. Although the purified and reconstituted Sox system oxidizes sulfide, its rate of sulfide oxidation in
C. pinatubonensis
JMP134 is too low to be physiologically relevant. The findings reveal how these sulfur-oxidizing enzymes participate in sulfide oxidation in a single bacterium.
ExPortal and the LiaFSR Regulatory System Coordinate the Response to Cell Membrane Stress in Streptococcus pyogenes
Authors: Lin Yibin , Sanson Misu A. , Vega Luis Alberto , Shah Brittany , Regmi Shrijana , Cubria M. Belen , Flores Anthony R.
Published: September 2020

Bacterial two-component systems sense and induce transcriptional changes in response to environmental stressors, including antimicrobials and human antimicrobial peptides. Since the stresses imposed by the host’s defensive responses may act as markers of specific temporal stages of disease progression or host compartments, pathogens often coordinately regulate stress response programs with virulence factor expression. The mechanism by which bacteria recognize these stresses and subsequently induce transcriptional responses remains not well understood. In this study, we showed that LiaFSR senses cell envelope stress through colocalization of LiaF and LiaS with the group A
Streptococcus
(GAS) ExPortal and is activated in direct response to ExPortal disruption by antimicrobials or human antimicrobial peptides. Our studies shed new light on the sensing of cell envelope stress in Gram-positive bacteria and may contribute to the development of therapies targeting these processes.