1,230 research outputs found
Effect of niobium on the directional solidification and properties of alnico alloys
The effect of niobium on the extent of columnar growth of grains and on the magnetic properties in Alnico alloys has been studied. Alloys containing 1 % Nb show maximum growth of columnar crystals. In columnar alloys, coercivity increases slowly with increasing niobium content up to approximately 1 %. With further increase in niobium, coercivity and remanence decrease. The maximum energy product (55 kJ m-3) has been obtained at 1 % Nb. Niobium addition has also been found to suppress the precipitation of the undesirable gamma phase
Developments of rubber material wear in conveyer belt system
Regular degradation of rubbers contribute frequent maintenance of conveyer belt system. This paper investigates wear rate and mechanisms of rubber and associated influential parameters based on the information available in literature. Abrasion, fatigue and roll formation are dominate wear mechanisms that are influenced by load, sliding velocity, hardness and friction. Correlations among influential parameters and their effect on rubber wear was established in details. Archad's equation does not work for rubber wear but researchers have proposed equations similar to that. Adhesion wear forms roll in the smooth surface when tear strength of rubber is low. Wear caused by adhesion is abrasion when surface texture is harsh. Hysteresis enhances fatigue wear if the substrate asperities are round or blunt
Size-dependent electronic-transport mechanism and sign reversal of magnetoresistance in Nd0.5Sr0.5CoO3
A detailed investigation of electronic-transport properties of Nd0.5Sr0.5CoO3
has been carried out as a function of grain size ranging from micrometer order
down to an average size of 28 nm. Interestingly, we observe a size induced
metal-insulator transition in the lowest grain size sample while the bulk-like
sample is metallic in the whole measured temperature regime. An analysis of the
temperature dependent resistivity in the metallic regime reveals that the
electron-electron interaction is the dominating mechanism while other processes
like electron-magnon and electron-phonon scatterings are also likely to be
present. The fascinating observation of enhanced low temperature upturn and
minimum in resistivity on reduction of grain size is found due to
electron-electron interaction (quantum interference effect). This effect is
attributed to enhanced disorder on reduction of grain size. Interestingly, we
observed a cross over from positive to negative magnetoresistance in the low
temperature regime as the grain size is reduced. This observed sign reversal is
attributed to enhanced phase separation on decreasing the grain size of the
cobaltite
Single spin universal Boolean logic
Recent advances in manipulating single electron spins in quantum dots have
brought us close to the realization of classical logic gates based on
representing binary bits in spin polarizations of single electrons. Here, we
show that a linear array of three quantum dots, each containing a single spin
polarized electron, and with nearest neighbor exchange coupling, acts as the
universal NAND gate. The energy dissipated during switching this gate is the
Landauer-Shannon limit of kTln(1/p) [T = ambient temperature and p = intrinsic
gate error probability]. With present day technology, p = 1E-9 is achievable
above 1 K temperature. Even with this small intrinsic error probability, the
energy dissipated during switching the NAND gate is only ~ 21 kT, while today's
nanoscale transistors dissipate about 40,000 - 50,000 kT when they switch
Tissue temperature monitoring using thermoacoustic and photoacoustic techniques
Real-time temperature monitoring with high spatial resolution (~1 mm) and high temperature sensitivity (1 °C or better) is needed for the safe deposition of heat energy in surrounding healthy tissue and efficient destruction of tumor and abnormal cells during thermotherapy. A temperature sensing technique using thermoacoustic and photoacoustic measurements combined with a clinical Philips ultrasound imaging system (iU22) has been explored in this study. Using a tissue phantom, this noninvasive method has been demonstrated to have high temporal resolution and temperature sensitivity. Because both photoacoustic and thermoacoustic signal amplitudes depend on the temperature of the source object, the signal amplitudes can be used to monitor the temperature. The signal is proportional to the dimensionless Grueneisen parameter of the object, which in turn varies with the temperature of the object. A temperature sensitivity of 0.5 °C was obtained at a temporal resolution as short as 3.6 s with 50 signal averages
An intensive audit on 250 patients of advanced ovarian cancer to improve quality of care in a tertiary referral oncology centre in India
Background: A clinical audit provides the framework to improve the quality of patient care in a systematic way. In this study, we intensively audited our 250 advanced epithelial ovarian cancer (EOC) patients aiming to improve our patient care.Methods: Ambispective study of 250 patients of advanced EOC was done from our prospectively maintained computerized database in the department of surgical oncology, AIIMS, New Delhi from 2013 to 2020.We audited the demographic profile, treatment patterns, perioperative and survival outcomes in different subgroups.Results: In this study, 83.6% stage III and 16.4% stage IV A. There was 62 (24.8%) upfront, 112 (44.8%) interval and 76 (30.4%) secondary group. 126 underwent cytoreductive surgery (CRS) and 124 CRS and hyperthermic intraperitoneal chemotherapy (HIPEC). There was 24.8% early and 8.4% late postop complications. Median follow up 50 months. Overall, the median disease-free survival (DFS) 39 months. PFS was 12 months among 68 patients with recurrence. Attrition rate 4%. In the upfront setting, the median DFS 44 months in CRS only group and DFS not reached (p=0.032) in CRS and HIPEC group still. In the interval setting, the median DFS 39 months in CRS only group and 44 months in CRS and HIPEC group (p=0.06). In recurrent setting, the median DFS 14 months in CRS group and 23 months in CRS and HIPEC group (p=0.02)Conclusions: Audit is an integral part of any clinical practice. It teaches us to improve the quality of care and thereby better outcomes. We recommend 6 monthly clinical audits in any cancer treatment for better outcomes in future
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