Effect of mechanical milling on the structural and dielectric properties of BaTiO 3 powders

Micro & nano letters

article

Samya Neogi¹  Ujjal Chowdhury²  Ashim Kumar Chakraborty³  Jiten Ghosh³ 

[1]Department of Physics, National Institute of Technology

[2]Nano Structured Materials Division, CSIR-Central Glass and Ceramic Research Institute

[3]Material Characterisation Division, CSIR-Central Glass and Ceramic Research Institute

关键词: permittivity;    nanoparticles;    nanofabrication;    barium compounds;    ball milling;    X-ray diffraction;    X-ray scattering;    ferroelectric ceramics;    particle size;    polymorphic transformations;    mechanical milling effect;    structural properties;    dielectric properties;    barium titanate;    ferroelectric materials;    electronic industries;    multilayer ceramic capacitor;    tetragonal powders;    size effect;    high-energy ball milling;    perovskite phase;    normal atmospheric condition;    crystalline phase;    atmospheric gas absorption;    orthorhombic phase;    X-ray diffraction;    small-angle X- ray scattering;    nanoceramics;    carbon absorption;    nanopowders;    dielectric constant;    particle size reduction;    polymorphic phase transformation;    humid atmosphere;    time 0 h to 110 h;    BaTiO3;   

DOI  :  10.1049/mnl.2013.0751

学科分类：计算机科学（综合）

来源: Wiley

【 摘 要 】

Background: Bupivacaine has been traditionally used as a local anesthetic of choice for regional anesthesia and analgesia. Ropivacaine has been marketed in our country with a claim of better motor profile, better safety profile and an equivalent analgesic profile when used in epidurals for postoperative pain.  This study aims to compare both drugs as an epidural infusion in terms of safety, analgesic efficacy by NRS score and patient satisfaction score and motor blockade by modified bromage score in postoperative period.Methodology: 70 patients of ASA grade I or II, of either sex between the age of 20-65 years, posted for orthopedic lower limb surgery under combined spinal epidural anesthesia were enrolled in this prospective randomised double blind study. The patients were randomly allocated to one of the two groups; Group 1 patients received 0.125% bupivacaine with 2 mg/ml fentanyl, while Group 2 patients received 0.2% ropivacaine, with 2 mg/ml fentanyl as an adjunct in epidural infusion postoperatively. Epidural infusion was started at the rate of 8 ml/hour after either four hours of administration of spinal anesthesia or at an NRS score of three, whichever was earlier. We evaluated the NRS scores, patient satisfaction scores and the need of rescue analgesic. Vital parameters and modified bromage score were also registered.Results: The pain score was similar in both groups at different time intervals, except at 15 and 30 min after starting epidural infusion, where the pain score was significantly lower in Group 2 when compared to Group 1 (p-value 0.007, 0.006 respectively). Patient satisfaction score was significantly more in Group 2 patients. There was no significant difference in requirement of rescue analgesia in two groups. Modified bromage grade was statistically more in Group 1.Conclusion:  We conclude that ropivacaine can be used as an alternative to bupivacaine for postoperative analgesia by epidural infusion, as it provides effective pain control with the added advantage of lower incidence of motor blockade.

【 授权许可】

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