Plain Ring Research Articles

A single plain ring is not associated with increased bacterial load on hands: An experimental study among healthcare worker students undertaking mock surgery

BackgroundAdequate hand hygiene is considered as one of the most effective strategies in healthcare-related infection prevention. The potential negative effect of rings in hand disinfection and thus, in increased nosocomial infections rates is still controversial. Therefore, the present study was designed with the purpose of examining if rings frequently exposed to surgical scrubbing were associated or not with increased bacterial counts. Methods32 volunteers were randomized into 4 groups: A (no rings), B (participants wore a ring), C (no rings and performed surgical scrubbing with chlorhexidine every 48 h) and D (participants wore a ring and performed surgical scrubbing every 48 h). Glove juice samples were obtained at day 0 (T0) and after a 90-min mock-surgery on day 14 (T1). Quantitative (number of UFC/mL) and qualitative data (microorganism type) were collected as study variables. ResultsAll groups were comparable at T0. All ring carriers obtained negative cultures at T1. Ring presence was not associated with higher bacterial counts; comparisons between A vs B groups and C vs D groups showed no statistically significant differences (p = 0.076 and 1.000). T1 negative cultures were more frequent in participants performing surgical scrubbing every second day (93.8 % vs 75 %), although this difference did not reach statistical significance (p = 0.332). ConclusionsThe presence of single plain ring does not seem to be associated with an increased hand bacterial load. Regular surgical scrubbing with chlorhexidine impregnated sponges reduces bacterial contamination of hands, even in the presence of plain rings.

In Silico Drug Repurposing Framework Predicts Repaglinide, Agomelatine and Protokylol as TRPV1 Modulators with Analgesic Activity.

Pain is one of the most common symptoms experienced by patients. The use of current analgesics is limited by low efficacy and important side effects. Transient receptor potential vanilloid-1 (TRPV1) is a non-selective cation channel, activated by capsaicin, heat, low pH or pro-inflammatory agents. Since TRPV1 is a potential target for the development of novel analgesics due to its distribution and function, we aimed to develop an in silico drug repositioning framework to predict potential TRPV1 ligands among approved drugs as candidates for treating various types of pain. Structures of known TRPV1 agonists and antagonists were retrieved from ChEMBL databases and three datasets were established: agonists, antagonists and inactive molecules (pIC50 or pEC50 < 5 M). Structures of candidates for repurposing were retrieved from the DrugBank database. The curated active/inactive datasets were used to build and validate ligand-based predictive models using Bemis−Murcko structural scaffolds, plain ring systems, flexophore similarities and molecular descriptors. Further, molecular docking studies were performed on both active and inactive conformations of the TRPV1 channel to predict the binding affinities of repurposing candidates. Variables obtained from calculated scaffold-based activity scores, molecular descriptors criteria and molecular docking were used to build a multi-class neural network as an integrated machine learning algorithm to predict TRPV1 antagonists and agonists. The proposed predictive model had a higher accuracy for classifying TRPV1 agonists than antagonists, the ROC AUC values being 0.980 for predicting agonists, 0.972 for antagonists and 0.952 for inactive molecules. After screening the approved drugs with the validated algorithm, repaglinide (antidiabetic) and agomelatine (antidepressant) emerged as potential TRPV1 antagonists, and protokylol (bronchodilator) as an agonist. Further studies are required to confirm the predicted activity on TRPV1 and to assess the candidates’ efficacy in alleviating pain.

Nickel-Based High-Bandwidth Nanostructured Metamaterial Absorber for Visible and Infrared Spectrum.

The efficient control of optical light at the nanoscale level attracts marvelous applications, including thermal imaging, energy harvesting, thermal photovoltaics, etc. These applications demand a high-bandwidth, thermally robust, angularly stable, and miniaturized absorber, which is a key challenge to be addressed. So, in this study, the simple and cost-effective solution to attain a high-bandwidth nanostructured absorber is demonstrated. The designed nanoscale absorber is composed of a simple and plain circular ring of nickel metal, which possesses many interesting features, including a miniaturized geometry, easily fabricable design, large operational bandwidth, and polarization insensitivity, over the previously presented absorbers. The proposed nanoscale absorber manifests an average absorption of 93% over a broad optical window from 400 to 2800 nm. Moreover, the detailed analysis of the absorption characteristics is also performed by exciting the optical light’s various incident and polarization angles. From the examined outcome, it is concluded that the nanostructured absorber maintains its average absorption of 80% at oblique incident angles in a broad wavelength range from 400 to 2800 nm. Owing to its appealing functionalities, such as the large bandwidth, simple geometry, low cost, polarization insensitivity, and thermal robustness of the constituting metal, nickel (Ni), this nano-absorber is made as an alternative for the applications of energy harvesting, thermal photovoltaics, and emission.

A novel polygonal ring rolling method

Polygonal rings are widely applied to fabricate critical ring components, such as cabin of aerospace equipment and large nuts. The traditional ring rolling method is difficult to fabricate polygonal rings owing to their non-rotary geometry characteristics. This paper proposes a novel polygonal ring rolling method using a simple rotary plain ring as the ring workpiece. Firstly, the motivations and principles of polygonal ring rolling method are proposed. Then, four typical feeding tool paths are designed and the plastic deformation modes and geometry evolutions of polygonal ring under these four feeding tool paths are revealed. Meanwhile, four typical feeding tool paths are optimized based on the stability of the polygonal ring rolling process. Finally, the polygonal ring rolling experiments are carried out and it is demonstrated that the proposed polygonal ring rolling method is feasible.

A Feeding Strategy in Inner L-Shape Ring Hot Rolling Process

In order to make the inner L-shape ring polling process with a closed die structure (ILRRCDS) on the top and bottom of the driven roll stable, at first, this paper established the mathematical model for ILRRCDS. Then, the plastic penetration and biting-in conditions for ILRRCDS were deduced based on plain ring rolling theory. Moreover, a feeding strategy that can realize a constant growth of the ring’s outer radius was proposed and the reasonable value ranges of the feed rate of the mandrel were determined. The numerical simulation model for ILRRCDS is established based on ABAQUS software. Finally, the equivalent plastic strain (PEEQ) and temperature distributions of rolled ring were obtained. The results indicated that the proposed feeding strategy can realize a stable ILRRCDS. At the end of ILRRCDS, the PEEQ at the inner radius surface of the ring is maximum, the PEEQ at the outer radius surface of the ring takes the second place, and the PEEQ at the middle part of ring is minimum. With the increase of rolling time, the higher temperature zone of the rolled ring gradually moves from the center part of the ring to the “inner corner zone” of the ring.

Development of L-sectioned ring for construction machines by profile ring rolling process

Recently, there is an increasing commercial interest in manufacturing rings with a complicated cross-sectional shape directly by a metal forming process instead of by machining. Profile ring rolling is one of the advanced metal forming technologies to manufacture large or small seamless profile rings. Compared with plain ring rolling, profile ring rolling can yield considerable savings in material cost and a shorter cycle time for additional machining. In this study, a profile ring rolling process for producing large-scale profile rings with an L-section for construction machine parts is developed. The manufacturing process of large-scale profile rings with L-section consists of a forging stage and a profile ring rolling stage. In the forging stage, the raw material is formed to initial blanks for profile ring rolling. The forged initial blanks are then formed to the final product shape in the profile ring rolling process, which is designed to occur in a single pass to minimize the cycle time. The design of the blank shape is very important, to enable the design of a profile ring rolling process without forming defects, such as fishtails, underfilling, and distortion of the ring. A finite-element (FE) analysis was performed to optimize the blank ring shape, with the objective of minimizing forming defects. After determination of the initial blank shape, the effects of process variables such as feed conditions of mandrel and axial rolls on the final product shape was investigated to improve the dimensional accuracy. Also, forming experiments were conducted based on the results of the FE analysis. The experimental results were in good agreement with the results of the FE analysis.

Effects of roll sizes on uniformity of strain and variation of configuration in cold-closed T-shaped rolling process of HE30 aluminum alloy ring

During ring rolling process, the roll sizes have significant influences on the forming quality of the deformed ring as well as the stability of the rolling process; thus, some works have been done on roll size effects in recent years. However, the previous work just focused on plain ring rolling process and the obtained results cannot be simply transplanted into profiled ring rolling process. In the profiled ring rolling process, due to the simultaneity of the expanding deformation of the ring radius and the configuration forming of the ring cross section, the effects of roll sizes are more complicated than that in the plain one. To reveal the discrepancies between the two rolling processes, the effects of roll sizes (i.e., the radius RD of the driving roll, the radius RM of the mandrel, and the fillet radius Rf of the groove entrance) on uniformity of strain and variation of configuration in cold-closed T-shaped ring rolling (CCT-RR) process are investigated deeply in this paper. The results show that (1) the ring is more likely to generate inner flaws and surface cracks if rolled by larger RD or smaller RM or larger Rf; (2) with RD or RM decreasing or Rf increasing, the expansion of outer radius decreases, so do the expansion of outer radius, while the filling depth increases; and (3) the equivalent plastic strain in the outside layer of the ring decreases with RD increasing or RM decreasing, but that in the inside layer increases faster; with Rf increasing, the outside layer increases and the inside layer decreases almost at the same speed in terms of equivalent plastic strain. The results will not only reveal the deformation mechanisms of CCT-RR process but also provide an important guideline in the processing design of the relevant cold profiled ring rolling processes.

Reversal and thermal stability of ordered moments in nano-rings of perpendicular anisotropy Co/Pd multilayers

Magnetic properties of the ring array made with ultrathin (Pd-/Co-layer thickness ~0.5/0.25 nm) Co/Pd multilayers are reported. Systematic investigation of magnetization loops M(H) at varying temperatures (T = 3–300 K) and magnetic relaxations (at T = 300 K) were carried out in a plain film and ring arrays with different ring widths of 660, 500 and 340 nm. The M(H) loops of all the samples show anisotropy distribution, a reversal mechanism facilitated by nucleation of the reverse domain followed by pinning dependent domain wall motion, and a thermally stable remanant state with Ub/kT > 250 (at T = 300 K, where Ub is the activation barrier). Both anisotropy distribution and pinning are found to increase in the nanostructures along with a precipitous rise of the reversal field below ≈100 K. These results are discussed in terms of the presence of chemically sharp/disordered interface regions and inter-layer interactions in the Co/Pd multilayers.

P156: Ring wearing in healthcare settings: an evidence-based update

Tens of thousands of healthcare workers worldwide can only wear a plain wedding ring at work, if any at all. This arose from policies citing early laboratory evidence that rings can carry clinically relevant bacteria, but with little supporting clinical data. Policies that are both invasive and perceived as lacking evidence create a broader scepticism of infection control guidelines: it is therefore important to regularly review the evidence for such guidance.

Impact of a Single Plain Finger Ring on the Bacterial Load on the Hands of Healthcare Workers

To investigate the impact of a single plain finger ring on the number and types of bacteria on the hands of healthcare workers (HCWs). Nonequivalent control groups, posttest only (preexperimental). A total of 121 HCWs wearing 1 plain ring and 113 HCWs wearing no rings had both hands sampled by the "glove juice" technique. Quantitative culture of the samples was performed and microorganisms were identified. Two Norwegian acute care hospitals. A total of 234 HCWs who had physical contact with patients. Total bacterial counts did not differ when hands with rings and hands without rings were compared, both according to nonpaired analysis (which compared the ring-bearing hands of ring-wearing HCWs to the hands of HCWs who did not wear rings [P=.661]) and according to paired analysis (which compared the ring-bearing and ring-free hands of ring-wearing HCWs [P=.071]). Staphylococcus aureus was recovered from 18.6% of the hands sampled, belonging to 26.9% of the HCWs, but neither paired nor nonpaired analysis showed any association with ring wearing. Gram-negative bacteria were recovered from 20.3% of the hands sampled, belonging to 28.6% of the HCWs. Ring-wearing HCWs were significantly more likely to be carriers of Enterobacteriaceae (P=.006), but paired comparison of the ring-bearing and ring-free hands of these HCWs did not show significant differences (P=.180). Carriage of nonfermentative gram-negative rods did not differ between the 2 groups, by either paired or nonpaired analysis. Wearing a single plain finger ring did not increase the total bacterial load on the hands, nor was it associated with an increased rate of carriage of S. aureus or nonfermentative gram-negative rods. However, plain rings were associated with an increased rate of Enterobacteriaceae carriage.

Dynamic explicit FE modeling of hot ring rolling process

A new FE modeling method of hot ring rolling was presented by solving key technologies such as contact and heat boundary conditions, motion control over guide rolls, and mass scaling. The method has the following features: 1) the elastic-plastic dynamic explicit approach instead of the static implicit approach is adopted to solve the process so as to greatly improve computational efficiency without sacrificing computational accuracy; 2) the coupled thermal-mechanical effect is considered as opposed to the conventional isothermal assumption, which is more practical; 3) in contrast to the simplified 2D or local 3D ring model, the full 3D ring is modeled to simulate the process. Based on the FE modeling method, two cases of hot plain ring rolling are simulated in the FEA software ABAQUS/Explicit. The simulation results are compared with the experimental measurements and the good agreement between them is observed regarding the material flow and the temperature distribution of the ring.

Prediction of spread, pressure distribution and roll force in ring rolling process using rigid–plastic finite element method

The ring rolling process involves 3D non-steady flow and continuous change of radius and thickness of the ring workpiece. In this study, a commercial FEM-code that is especially tailored to ring rolling process, SHAPE-RR™, is used to predict spread, pressure distribution and roll force in plain and T-shaped ring rolling processes. Two cases of plain and T-shaped rings are, respectively, simulated for the prediction of side spread by changing feed-rate and groove factor. Plain ring rolling is simulated for the prediction of pressure distribution and roll force. Compared with earlier experimental works, the results of simulations show good quantitative agreements. It is concluded that the solution tool can be utilized in design and analysis of ring products, process, and tooling and equipment.

강-열점소성 유한요소법을 이용한 알루미늄 링압연 공정 해석

The ring rolling process involves not only three-dimensional non-steady material flow and continuous change of radius and thickness of the ring workpiece but also heat transfer among workpiece, rolls and environment. In this study, deformation and heat transfer analyses were conducted by using the three-dimensional thermo-rigid-plastic finite element method. Three cases of plain ring rolling process were, respectively, simulated for the predictions of roll forces and the highest temperature zone duringbr/ the aluminum process that ductile fracture often occurs. In addition, to prevent fishtail phenomena of the ring workpiece, axial rolls were used for this study.br/

강소성 유한요소법을 이용한 링 압연 공정에서의 폭 퍼짐량 및 접촉영역 예측

The ring rolling process involves three-dimensional non-steady material flow and continuous change of radius and thickness of the ring workpiece. In this study, the deformation analysis and geometric updating algorithm of the ring rolling process were verified by using the three-dimensional rigid-plastic finite element method. Manufacturing processes for plain ring and T-shaped ring were investigated by comparing experiments with simulation results, especially in side spread, load-stroke and pressure distribution, showing a good agreement. It was concluded that the simulation method would be a useful tool for the design of a ring rolling process.

3-D microfabricated toroidal planar inductors with different magnetic core schemes for MEMS and power electronic applications

Micromachined toroidal planar inductors that have three different magnetic core structures have been designed, fabricated, and characterized for MEMS and power electronic applications. A plain ring core shows a high inductance value of 10 /spl mu/H in a low frequency range below 2 kHz, whereas both a ring core with an air gap and a spiral type core show higher inductance values in a high frequency range of 2 kHz-1 MHz. The inductors have a low resistance value of /spl sim/1.5 /spl Omega/ with total dimensions 4 mm/spl times/1.5 mm/spl times/120 /spl mu/m.

Contribution to static analysis of load-bearing concrete tunnel lining built by shield-driven technology

Load-bearing concrete tunnel linings for shield-driven tunnels have been used very often in the last decade. Different forms, means of assembly and coupling of the concrete tunnel lining elements have been developed; and current software products in the field of structural analysis provide new possibilities for more precise modeling and 'computation. In this paper, a simplified comparative static computation for an example of an underground metro concrete tunnel lining is shown. For the same dimensions of the tunnel cross-section and the same earth environment model, different means of assembly and coupling were used. A comparison of the forces and deformations achieved by using different plain ring (2D) and spatial (3D) computing models show that traditional plain ring models give more accurate results than spatial (3D) models.

Preform design in ring rolling processes by the three-dimensional finite element method

Perform design by the three-dimensional finite element method has been carried out for plain ring rolling and T-section profiled ring rolling. The application of the backward tracing scheme for perform design in ring rolling processes demonstrates, for the first time, the extension of the scheme into three dimensions. The preform design in plain ring rolling aims at obtaining a preform which simulates a final plain ring product with uniform axial height. Loading simulations were carried out for two progressively modified preforms derived from the result of loading simulations with a rectangular-shaped ring. Then, backward tracing was applied to obtain a final preform for the specified product configuration of uniform axial height. The preform in the T-section profiled ring rolling process was to be designed to simulate a final profiled ring product with complete filling in the groove and uniform axial height. The final preform shape for plain ring rolling was selected as a trial preform in T-section profiled ring rolling. A more satisfactory preform was obtained from the backward tracing results. It was shown by forward simulation that the final preform was good enough to satisfy the design criteria.

Ring rolling process simulation by the three dimensional finite element method

The finite element code “RING” was developed for the analysis of ring rolling. A special feature of the program is the updating procedure in three-dimensional deformation. A spatially fixed mesh system including deforming region of the workpiece is constructed based on the shape changes of the ring at each time step. Several simulations are performed with the program “RING”, and the results are compared with experimental data found in the literature. Good agreement between the simulation results and experiments was obtained in terms of geometrical changes of rings in plain ring rolling and T-shaped profiled ring rolling.

Fatigue cracking in damaged cylinders subjected to cyclic compressive loading

This paper presents the results of analytical and experimental investigations of the occurrence of cracking in thin-walled structures which are damaged and subjected to axial compressive loading with cyclically varying magnitude. The experimental investigation comprised nine test specimens, namely three plain cylinders, three plain ring stiffened and three T-ring stiffened cylinders. The paper describes the method whereby damage was inflicted on the cylinders and describes test results, including strain gauge data. The analysis was performed using a commercial finite element program which incorporated non-linearities in the strain-displacement and stress-strain relationships. The results of the analysis were found to be in good agreement with the test results, and the occurrence of cracking was noted to be dependent on the combined levels of tensile residual stresses due to the damage and to the levels of compressive stresses due to the imposed loading.

Strength of damaged ring and orthogonally stiffened shells—Part II: T-ring and orthogonally stiffened shells

This paper is the second of two parts describing the procedure of, and results from, a series of tests on ring and orthogonally stiffened thin-walled shells. The primary purpose of the work was to investigate the collapse behaviour of the shells subjected to simulated damage and then tested under a combination of external pressure and axial compressive loading. The test specimens consisted of two five-bay cylinders stiffened with plain ring stiffeners; two three-bay cylinders stiffened with T-ring stiffeners and two three-bay orthogonally stiffened cylinders, one with twenty stringers, and the other with forty. This Part II deals with the tests on the T-ring and orthogonally stiffened shells. It is concluded from the test results that the T-ring stiffeners were much more effective than the corresponding plain-rings with regard to limiting the deformations which would result from minor impacts and practical conditions of loading. It is generally recommended that plain rings should not be used in shells which form parts of structural components potentially liable to damage from a minor collision, etc. It is also recommended that further work be done, including analysis and testing, to determine the optimum design of T-ring stiffeners to limit the effects of damage in an effective manner.