Efficient and optimized identification of generalized Maxwell viscoelastic relaxation spectra

Viscoelastic relaxation spectra are essential for predicting and interpreting the mechanical responses of materials and structures. For biological tissues, these spectra must usually be estimated from viscoelastic relaxation tests. Interpreting viscoelastic relaxation tests is challenging because the inverse problem is expensive computationally. We present here an efficient algorithm that enables rapid identification of viscoelastic relaxation spectra. The algorithm was tested against trial data to characterize its robustness and identify its limitations and strengths. The algorithm was then applied to identify the viscoelastic response of reconstituted collagen, revealing an extensive distribution of viscoelastic time constants. © 2015 Elsevier Ltd

Application of Reduced Differential Transform Method for Solving Nonlinear Reaction-Diffusion-Convection Problems

In this paper, Reduced differential transform method is presented for solving nonlinear reactiondiffusion- convection initial value problems. The methodology with some known techniques shows that the present approach is simple and effective.To show the efficiency of the present method, four interesting examples is given

Contamination of sediments with heavy metals Cd, Cu, Fe, Pb in the east of Anzali Lagoon

The surface layer of sediments in the east of the Anzali Lagoon was surveyed for heavy metal contamination during the year 2004 at the National Inland Water Aquaculture Institute. Samples were obtained by sediment sampler (Eckman Grab) from Pirbazar River, Pasikhan and Selkeh. The samples were dried and treated by wet digestion (HN0_3, H_2SO_4, HClO_4) under open reflux condition. Concentration of Pb, Fe, Cu and Cd were 7.92, 0.2775%, 25.8 and 1.645 kg/g dry weight respectively. The Fe and Cu have the highest concentration. We found that in the study area, Pirbazar was the most contaminated with the selected heavy metals

Remodeling by fibroblasts alters the rate-dependent mechanical properties of collagen

The ways that fibroblasts remodel their environment are central to wound healing, development of musculoskeletal tissues, and progression of pathologies such as fibrosis. However, the changes that fibroblasts make to the material around them and the mechanical consequences of these changes have proven difficult to quantify, especially in realistic, viscoelastic three-dimensional culture environments, leaving a critical need for quantitative data. Here, we observed the mechanisms and quantified the mechanical effects of fibroblast remodeling in engineered tissue constructs (ETCs) comprised of reconstituted rat tail (type I) collagen and human fibroblast cells. To study the effects of remodeling on tissue mechanics, stress-relaxation tests were performed on ETCs cultured for 24, 48, and 72 h. ETCs were treated with deoxycholate and tested again to assess the ECM response. Viscoelastic relaxation spectra were obtained using the generalized Maxwell model. Cells exhibited viscoelastic damping at two finite time constants over which the ECM showed little damping, approximately 0.2 s and 10-30 s. Different finite time constants in the range of 1-7000 s were attributed to ECM relaxation. Cells remodeled the ECM to produce a relaxation time constant on the order of 7000 s, and to merge relaxation finite time constants in the 0.5-2 s range into a single time content in the 1 s range. Results shed light on hierarchical deformation mechanisms in tissues, and on pathologies related to collagen relaxation such as diastolic dysfunction. Statement of Significance As fibroblasts proliferate within and remodel a tissue, they change the tissue mechanically. Quantifying these changes is critical for understanding wound healing and the development of pathologies such as cardiac fibrosis. Here, we characterize for the first time the spectrum of viscoelastic (rate-dependent) changes arising from the remodeling of reconstituted collagen by fibroblasts. The method also provides estimates of the viscoelastic spectra of fibroblasts within a three-dimensional culture environment. Results are of particular interest because of the ways that fibroblasts alter the mechanical response of collagen at loading frequencies associated with cardiac contraction in humans. © 2016 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved

The efficacy of 100 and 300 mg gabapentin in the treatment of carpal tunnel syndrome

Carpal tunnel syndrome (CTS) is a neuropathy due to the compression of the median nerve. It is shown that gabapentin in high doses is effective in treatment of CTS patients. In this study we evaluated the efficacy of low doses of gabapentin in treatment of CTS patients. Ninety patients with CTS were randomly assigned to groups A, B and C. Gabapentin was administered to group A with dose of 100 mg/day and to group B with dose of 300 mg/day for 2 months. Group C received no treatment. Before and after treatment, patients were evaluated using Visual analogue scale (VAS) for pain and parasthesia, Boston carpal tunnel questionnaire (BCTQ) including Symptom Severity Scale (SSS) and Functional Status Scale (FSS) to evaluate the efficacy of the treatment. The pinch and grip strength was also measured. There was significant improvement in VAS, grip strength, pinch strength, SSS, FSS and BCTQ score in all three groups (p < 0.05), but the changes in CMAP and SNAP was not significant. Groups A and B in comparison to group C had significantly better improvement in VAS, pinch strength, SSS, FSS and BCTQ total score (p < 0.05). There was significantly more improvement in pinch strength and SSS score in group B compared to group A (p < 0.05). Gabapentin in low doses is a useful drug in treatment of CTS symptoms with no side effects and intolerance. Gabapentin with dose of 300 mg/day is more effective than the dose of 100 mg/day. © 2015 by School of Pharmacy Shaheed Beheshti University of Medical Sciences and Health Services