Renal stone containing calcium oxalate monohydrate as a major component was subjected to microhardness and acoustic studies in order to understand its mechanical properties in vitro and use them to help in the treatment procedures for more effective stone fragmentation. The chemical composition and the crystalline nature of the stone were verified using Fourier Transform Infrared spectroscopy, X-ray diffraction and the stone was also analyzed using thermo gravimetric analysis and by differential thermal analysis. The microhardness values were almost constant around 1000 MNm- 2 in the load range of 1.96 N-9.8 N. The values of fracture toughness and brittleness index for the stone in this load range was varying from 1.12 (0.307) MNm- 3/2 to 1.48 (0.296) MNm- 3/2 and 674.25 m- 1/2 to 878.07 m- 1/2 respectively. The density of the stone and the ultrasonic longitudinal wave velocity in the stone were found to be 1880 kgm- 3 and 3399 ms- 1 respectively indicating that the urinary stone under study was a compact one. The acoustic impedance and the dynamic modulus values were calculated as 6.39 × 106 kgm- 2 s- 1and 21.72 GNm- 2 respectively. © 2007 Elsevier B.V. All rights reserved.

Arunai Nambiraj N

Department of Physics

School of Advanced Sciences

Vellore Campus

Kalainathan S

Ali A.M

Palanichamy P.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Materials Letters

The study explores calcium oxalate crystal inhibiting characteristic of polyacrylic acid (pAA), an anionic polymer in in vitro and in vivo. Animals were divided into 5 groups where group 1 served as control, group 2 were made hyperoxaluric by supplementing with Ethylene glycol (EG) 0.75% (v/v) for 30 days. Group 3, 4 &amp; 5 were also given with EG and treated simultaneously with 2.5, 5 &amp; 10 mg of pAA/kg of body weight, respectively. Urine, serum and tissue analyses along with histological studies were performed at the end of the 30 days study. In vitro crystallization was significantly inhibited by pAA and further it was supported by particle size analyses, XRD and FT-IR studies. Toxicological analyses showed that pAA was safe to use in animals at concentrations below 100 mg/kg BW. In vivo anti-urolithic study showed significant improvement in urinary lithogenic factors (calcium, oxalate, phosphate, citrate &amp; magnesium) and renal function parameters (creatinine, urea and protein). Tissue analyses on anti-oxidant enzyme activity and lipid peroxides showed maintenance of tissue antioxidant status in the pAA supplemented rats and histological studies demonstrated the nephroprotection offered by pAA and were concurrent to the biochemical analyses. Supplementation of pAA not only reduces the crystal aggregation but also regulates the expression and localization of crystal inhibiting proteins and gene expression of inflammatory cytokines in experimental animals. In summary, pAA is a potent anti-urolithic agent in rats and we can propose that 10 mg/kg body weight is the effective dosage of pAA and this concentration can be used for further studies. © 2016 Elsevier Ireland Ltd.

Chemico-Biological Interactions

Polyacrylic acid attenuates ethylene glycol induced hyperoxaluric damage and prevents crystal aggregation in vitro and in vivo

Calcium oxalate monohydrate (COM) is the primary constituent of the majority of stones formed in the urinary tract. Mechanical properties of renal calculi dictate how a stone interact and disintegrate with mechanical forces produced by shock wave and laser lithotripsy techniques. Tensile stresses may be more effective in some instances in disrupting material because most materials are weaker in tension than compression. Urinary stone containing COM as a major component was subjected to tensile, flexural and compressive strength studies in order to understand its mechanical properties in vitro. The calculated tensile breaking strength for the urinary stone from three tests varies from 0.57 MNm-2 to 1.52 MNm-2. The flexural strength and the flexural modulus of the urinary stone were calculated as 5.17 MNm-2 and 2.22 GNm-2 respectively while the observed compressive strength was 6.11 MNm-2. The chemical composition and the crystalline nature of the stone were verified using Fourier Transform Infrared spectroscopy and X-ray diffraction.

Advanced Materials Research

Tensile, Flexural and Compressive Strength Studies on Calcium Oxalate Monohydrate Urinary Stone

Kidney or gall-bladder stones are solid accretions (crystals) of dissolved minerals in urine or bile juice found inside the kidneys or urethras and gall bladder, with varying size from as small as a grain of sand to as large as a golf ball, the occurrence whose in the human is well known, although its pathogenesis is not well understood. According to literature, a number of biomaterials, such as collagen, blood vessel walls, DNA, RNA etc., are found to possess the property of electrets which is an electric analogue of a permanent magnet having the capability to retain quasipermanently, an induced polarization. In order to understand about the occurrence and the physical properties of stone formation in the human tissues, the study of its electret behaviour and conductivity becomes imperative which implies the fact of indulging in its growth inhibition, if their deposition is identified using scans. Thus, in this paper, in order to understand the mechanism of growth of these nephrolithiasis, we enumerated the electrical behaviour of the stone, by using the XRD (X-Ray Diffraction) analysis after their collection from different patient in and around the region and subsequently the dielectric constant of the stone was interpreted.

Studies on the Dielectric Properties of Natural Urinary Stones

Calcium oxalate is the most significant component of urinary stones, usually in its monohydrate form. The mechanisms for the formation of calcium oxalate urinary stones are still not understood, though it is thought that organic macromolecules play a significant role. Calcium oxalate monohydrate (COM) urinary stone was subjected to dielectric studies in order to understand the formation and growth of the renal stones in vivo and use them to help in the treatment procedures for more effective stone fragmentation. The chemical composition and the crystalline nature were verified using Fourier Transform Infrared spectroscopy, X-ray diffraction and thermal analysis. The dielectric parameters for the COM renal stone namely, capacitance, dielectric loss coefficient, impedance, and resistance were measured at room temperature and hence the dielectric constant and the alternating current conductivity were calculated in the frequency range 200 Hz to 5 MHz. The measured values and the dielectric constant showed systematic variations up to 10 kHz. The alternating current conductivity was almost constant up to 2.0 kHz and then showed systematic increase at around 100 kHz and reaches a maximum value at around 5 MHz. The results may be used in further studies of renal stones about their formation and growth.

Dielectric Behavior of Calcium Oxalate Monohydrate Urinary Stone

Mechanical properties of renal calculi dictate how a stone interacts and disintegrates by shock wave or intracorporeal lithotripsy techniques. Renal stones of different compositions have large variation in their mechanical strength and susceptibilities to shock waves. Operated urinary stones and artificially developed stones using pharmaceutical methods, composed of phosphates were subjected to tensile, flexural and compressive strength studies using universal testing machine. The infrared spectra confirmed the presence of hydroxyapatite in both the natural stones and struvite with calcium oxalate trihydrate in one stone and struvite with uric acid in the other. The X-ray diffraction analyses confirmed their crystalline nature. It has been observed that the flexural properties depend on the size of the sample even for the samples cut from a single stone. The compressive strengths were almost 25 times larger than the tensile strengths of the respective natural stones as well as the artificial stones prepared.

Journal	Data powered by TypesetMaterials Letters
Publisher	Data powered by TypesetElsevier BV
ISSN	0167-577X
Open Access	0