Case Of Hardening Research Articles

Prospective observational study on the prognosis of ureteral lesions caused by impacted stones via dual-energy spectral computed tomography

ObjectiveUreteral lesions caused by impacted ureteral stones are likely to result in postoperative ureteral stricture. On this basis, the study aimed to investigate if dual-energy spectral computed tomography can predict ureteral hardening caused by impacted stones and to explore the relationship between different types of ureteral lesions and the risk of ureteral stricture. MethodsThis prospective study collected data of 93 patients with impacted stones from hospital automation system during January 2018 to October 2019. They underwent an abdominal scan on a dual-energy spectral computed tomography. During surgery, the operator used ureteroscopy to identify ureteral lesions, which were classified into four categories: edema, polyps, pallor, and hardening. Seven months later, 90 patients were reviewed for the degree of hydronephrosis. ResultsEndoscopic observations revealed 38 (41%) cases of ureteral edema, 20 (22%) cases of polyps, 13 (14%) cases of pallor, and 22 (24%) cases of hardening. There were significant differences in hydronephrosis, the period of impaction, the calcium concentration of the ureter, and the slope of the spectral Hounsfield unit curve between the four groups. After that, we evaluated the factors associated with ureteral hardening and found that the calcium concentration of the ureter and hydronephrosis remained independent predictors of ureteral hardening. Receiver operating characteristic curve analysis showed that 5.3 mg/cm³ calcium concentration of the ureter is an optimal cut-off value to predict ureteral hardening. The result of follow-up showed that 80 patients had complete remission of hydronephrosis, with a complete remission rate of 61.9% (13/21) in the hardening group and 97.1% (67/69) in the non-hardening group (p<0.001). ConclusionCalcium concentration of the ureter is an independent predictor of ureteral hardening. Patients with ureteral hardening have more severe hydronephrosis after ureteroscopic lithotripsy. When the calcium concentration of the ureter is less than 5.3 mg/cm³, ureteral lesions should be actively treated.

Uncovering inner detached resonance curves in coupled oscillators with nonlinearity

Detached resonance curves have been predicted in multi-degree-of-freedom nonlinear oscillators, when subject to harmonic excitation. They appear as isolated loops of solutions in the main continuous frequency response curve and their detection may thus be hidden by numerical or experimental analysis. In this paper, an analytical approach is adopted to predict their appearance. Expressions for the amplitude-frequency equations and bifurcation curves are derived for a two degree-of-freedom system with cubic stiffness nonlinearity, and the effect of the system parameters is investigated. The interest is specifically towards the occurrence of closed detached curves appearing inside the main continuous frequency response curve, which may lead to a dramatic reduction of the amplitude of the system response. Both cases of hardening and softening stiffness characteristics are considered. The analytical findings are validated by numerical analysis.

On the ageing of polymers and the time‐shifting procedure

The time‐shifting procedure, originally developed for time‐temperature equivalence in the modelling of polymers mechanical behaviour, has later on been extended to time‐age equivalence. The present paper discusses both situations in the context of linear viscoelastic behaviour, from the point of view of mathematical representation and the fitting of experimental data. The general equations in the cases of ageing and non‐ageing are introduced and the cases of hardening and softening types of ageing are precisely characterised. Situations in which time shifting can prove effective are delimited and alternative more general expressions are proposed.

A case of hardening of the skin and scleroderma like changes on biopsy: Is it scleroderma or not? A review of pseudoscleroderma and differential diagnosis

Introduction: Scleroderma is an autoimmune connective tissue disease characterized by pervasive systemic multiple organ fibrosis. Definitive diagnosis can be difficult as this disease has a highly variable disease spectrum and course. Further complicating matters, there exist several less commonly known imitators, termed pseudosclerodermas, which force a more open differential than might be presumed initially. Case Report: We present the case of a 46-year-old female diagnosed with pseudoscleroderma. Conclusion: This case emphasizes the importance of skin biopsy while not on steroids and also the need to maintain a broad differential even in the setting of biopsy results. (This page in not part of the published article.) International Journal of Case Reports and Images, Vol. 6 No. 9, September 2015. ISSN – [0976-3198] Int J Case Rep Images 2015;6(9):546–551. www.ijcasereportsandimages.com Sizemore et al. 546 CASE REPORT OPEN ACCESS A case of hardening of the skin and scleroderma like changes on biopsy: Is it scleroderma or not? A review of pseudoscleroderma and differential diagnosis Travis C. Sizemore, Gulzar Merchant, Katharine Whitfield

Dynamics of a Duffing nanomechanical resonator coupled to a single-electron transistor: A master equation approach

We investigate the nonlinear dynamics of a classical Duffing nanomechanical resonator coupled to a single-electron transistor (SET) using a master equation formalism. We consider both the cases of hardening and softening stiffnesses of the Duffing regime while assuming linear coupling between the SET and the resonator. We first derive scaled master equations for the coupled system and define a parameter that characterizes the effective nonlinearity in the system. Solving the equations using a method of moment approximations and validating the approximations independently using finite element solutions, we conclude that the coupled system reaches a steady state and that interaction with the SET damps the motion of the resonator at a significantly higher rate in the hardening Duffing case in comparison with the case of a linear harmonic resonator. The concomitant conclusion that the steady state is attained more rapidly suggests that the hardening stiffness Duffing regime has better prospects for sensing applications than the linear regime. Moreover, analysis of the variance of the resonator displacement in the steady state indicates that lower steady-state effective temperatures are obtained in the nonlinear case. In the case of softening stiffness, dynamical instability occurs in certain parameter regimes implying that the SET transfers energy to the resonator in these regimes. Interestingly, the onset of instability is preceded by the appearance of periodic orbits in phase space. Since weak coupling between the SET and the resonator is assumed throughout, our analysis indicates that a variety of important phenomena, including negative damping, can arise from purely nonlinear motion of the nanomechanical resonator in this regime.

Deformation of a Comparatively Small-Sized Gear Caused by Induction Hardening : Consideration on the distortion Mechanism of Inner Diameter Due to Quenching

One of the important distortions of the gear teeth due to quenching is the one produced on the inner diameter, which must be fitted to the shaft properly. Distortion of the inner diameter of the gear, caused by induction hardening with simultaneous quenching of all teeth using a circular inductor surrounding the gear, was investigated. In such case of hardening, we can deal with a disk instead of a gear to study the tendency of the distortion. The stress and the distortion due to thermal change only were considered theoretically with the disk and the effects of quenching transformation were also discussed briefly. From these considerations, the mechanisms of the inner diameter distortion have been explained and it has been made possible to choose the method of induction hardening effective to reduce the inner diameter distortion.

Phenol‐formaldehyde and allied resins. V.—Synthesis of a bridged decanuclear novolak and a case of hardening by way of meta‐substitution

AbstractThe bridged decanuclear novolak (V) has been synthesized rationally as a non‐crystalline chemical individual from 2: 6‐bis‐2′‐hydroxy‐5′‐methylbenzyl‐4‐bromophenol (I) by way of the dimethylol derivative (II) which on reaction with 2: 4‐xylenol furnished 2: 6‐bis‐2′‐hydroxy‐3′‐(2″‐hydroxy‐3″: 5″‐dimethylbenzyl)‐5′‐methylbenzyl‐4‐bromophenol (III) which was debrominated to the pentanuclear novolak (IV). On reaction with an equivalent of formaldehyde in acetic acid, using sulphuric acid as catalyst, the latter gave the required bridged decanuclear novolak (V). In the presence of excess of acid formaldehyde, both the pentanuclear and the decanuclear novolaks were readily converted into hardened products whose infra‐red absorption spectra indicated the formation of methylene bridges in meta‐position to the hydroxyl groups.

Discussion on "Heat treatment" at the Birmingham Graduate Section of the Institution

MR. D. A. TILT (Chairman, Birmingham Graduate Section) who presided opened a very animated discussion which was taken part in by numerous graduates and visitors. Mr. McNab, he said, had told them that heat treatment consisted in getting a piece of steel with a few crystals in i t ; on heating it, these started running round and round, and in the case of hardening, it was hoped, by quenching at a certain temperature, to catch them where they ought to be, but in most cases of hardening, this point was missed, and the desired results were not obtained.