25,010 research outputs found
NUMERICAL TRANSIENT HEAT TRANSFER ANALYSIS OF REACTOR FOR MAGNESIUM BASED ALLOY FOR HYDROGEN STORAGE APPLICATION
Metal hydrides are potential hydrogen storage media. They release hydrogen at moderate temperatures and pressures. Magnesium hydride is a promising approach for stationary power system application, due to high hydrogen storage capacity by weight. Magnesium hydride based reactor design is more complex due to high thermal energy release and absorption during hydriding reaction and dehydriding reaction, respectively. In this study, results of a numerical modeling study are presented for a 1.5 kg Magnesium alloy based hydriding reactor. Temperature profile in the reactor is computed by FEM analysis using ANSYS software for hydriding and dehydriding reaction. FEM analysis indicates that the reactor temperature is raised from 200 C to 422 ÂșC in 20 minutes during the hydriding process. Hence, a âcooling systemâ is required for maintaining temperature during the hydriding process. During the dehydriding process, maximum temperature drop occurs from 350 C to 189 ÂșC in 20 minutes. Therefore, an external heat source of 2 kW is required for maintaining the temperature during dehydriding. Details are presented
Some studies on olivine fines and clay mixtures
Olivine is a mineral composed of forsterite (2 MgO.SiO2) as major and fayalite (2 FeO.SiO,) as minor phases. During proÂŹcessing of olivine minerals for foundry and other uses, lot of fines (around -100 mesh) are generated. The present study has been carried out on the olivine fines collected from the Salem district of Tamil Nadu to explore the possibilities of converting these fines into value added ceramic products by reaction sintering with clan Different combinations of olivine fines and clay have been formulated and the mixtures are heated at various temperaÂŹtures in the form of pellets. The sintering kinetics and physical properties have been studied and discussed in this paper. XRD & SEM and studies are also carried out to confirm the phases formed
Statistical Mechanics of Charged Particles in Einstein-Maxwell-Scalar Theory
We consider an -body system of charged particle coupled to gravitational,
electromagnetic, and scalar fields. The metric on moduli space for the system
can be considered if a relation among the charges and mass is satisfied, which
includes the BPS relation for monopoles and the extreme condition for charged
black holes. Using the metric on moduli space in the long distance
approximation, we study the statistical mechanics of the charged particles at
low velocities. The partition function is evaluated as the leading order of the
large expansion, where is the spatial dimension of the system and will
be substituted finally as .Comment: 11 pages, RevTeX3.
Failure time and microcrack nucleation
The failure time of samples of heterogeneous materials (wood, fiberglass) is
studied as a function of the applied stress. It is shown that in these
materials the failure time is predicted with a good accuracy by a model of
microcrack nucleation proposed by Pomeau. It is also shown that the crack
growth process presents critical features when the failure time is approached.Comment: 13 pages, 4 figures, submitted to Europhysics Letter
Medical expulsive therapy for the management of ureteric calculi
Ureteric stones in endemic areas if treated on OPD basis with helps of oral drugs saves hospitalization and economic burden to the patient and the hospital. A prospective study was carried out for 9 and half years in two medical colleges by offering two different regimes to patients on random basis and regular follow-up was done on OPD basis. The stone passage rate was highest in the lower ureter 1/3rd (80%) followed by middle 1/3rd (45%) and upper 1/3rd (40%). The patients who were offered regime 1 which included diuretics had less success rate then that with regime 2 which included drugs like nifedipine and steroids. Treatment of ureteric stones on OPD basis in endemic areas is a boon for the patients and for the health management system in terms of cost and health care system
Ab interno trabecular bypass surgery with SchlemmÂŽs canal microstent (Hydrus) for open angle glaucoma
Background:
Glaucoma is a leading cause of irreversible blindness. A number of minimallyâinvasive surgical techniques have been introduced as a treatment to prevent glaucoma from progressing; ab interno trabecular bypass surgery with the Schlemm's canal Hydrus microstent is one of them.
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Objectives:
To evaluate the efficacy and safety of ab interno trabecular bypass surgery with the Hydrus microstent in treating people with open angle glaucoma (OAG).
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Search methods:
On 7 May 2019, we searched CENTRAL (2019, Issue 5), which contains the Cochrane Eyes and Vision Trials Register; Ovid MEDLINE; Ovid Embase; the ISRCTN registry; ClinicalTrials.gov; and the WHO ICTRP.
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Selection criteria:
We searched for randomised controlled trials (RCTs) of the Hydrus microstent, alone or with cataract surgery, compared to other surgical treatments (cataract surgery alone, other minimallyâinvasive glaucoma device techniques, trabeculectomy), laser treatment, or medical treatment.
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Data collection and analysis:
A minimum of three authors independently extracted data from reports of included studies, using a data collection form and analysed data, based on standard Cochrane methods.
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Main results:
We included three published studies, with 808 people randomised. Two studies had multiple international recruitment centres in the USA and other countries. The third study had several sites based in Europe. All three studies were sponsored by the Hydrus manufacturer Ivantis Inc. All studies included participants with mainly mild or moderate OAG (mean deviation between â3.6 dB (decibel) and â8.4 dB in all study arms), which was controlled with medication in many participants (mean medicated intraocular pressure (IOP) 17.9 mmHg to 19.1 mmHg). There were no concerns regarding allocation concealment bias, but masking of outcome assessors was high or unclear risk in all studies; masking of participants was achieved, and losses to followâup were not a concern.
Two studies compared the Hydrus microstent combined with cataract surgery to cataract surgery alone, in participants with visually significant cataracts and OAG.
We found moderateâcertainty evidence that adding the Hydrus microstent to cataract surgery increased the proportion of participants who were medicationâfree from about half to more than three quarters at 12âmonth, shortâterm followâup (risk ratio (RR) 1.59, 95% confidence interval (CI) 1.39 to 1.83; 2 studies, 639 participants; IÂČ = 0%; and 24âmonth, mediumâterm followâup (RR 1.63, 95% CI 1.40 to 1.88; 2 studies, 619 participants; IÂČ = 0%).
The Hydrus microstent combined with cataract surgery reduced the mediumâterm mean change in unmedicated IOP (after washout) by 2 mmHg more compared to cataract surgery alone (mean difference (MD) â2.00, 95% CI â2.69 to â1.31; 2 studies, 619 participants; IÂČ = 0%; moderateâcertainty evidence), and the mean change in IOPâlowering drops (MD â0.41, 95% CI â0.56 to â0.27; 2 studies, 619 participants; IÂČ = 0%; lowâcertainty evidence). We also found lowâcertainty evidence that adding a Hydrus microstent to cataract surgery reduced the need for secondary glaucoma surgery from about 2.5% to less than 1% (RR 0.17, 95% CI 0.03 to 0.86; 2 studies, 653 participants; IÂČ = 27%; lowâcertainty evidence).
Intraocular bleeding, loss of 2 or more visual acuity (VA) lines, and IOP spikes of 10 mmHg or more were rare in both groups; estimates were imprecise, and included both beneficial and harmful effects. There were no cases of endophthalmitis in either group.
No data were available on the proportion of participants achieving IOP less than 21 mmHg, 17 mmHg, or 14 mmHg; healthârelated quality of life (HRQOL), or visual field progression.
One study provided shortâterm data for the Hydrus microstent compared with the iStent trabecular microâbypass stent (iStent: implantation of two devices in a single procedure) in 152 participants with OAG (148 in analyses). Use of the Hydrus increased the proportion of medicationâfree participants from about a quarter to about half compared to those who received iStent, but this estimate was imprecise (RR 1.94, 95% CI 1.21 to 3.11; lowâcertainty evidence). Use of the Hydrus microstent reduced unmedicated IOP (after washout) by about 3 mmHg more than the iStent (MD â3.10, 95% CI â4.17 to â2.03; moderateâcertainty evidence), and the use of IOPâlowering medication (MD â0.60, 95% CI â0.99 to â0.21; lowâcertainty evidence). Both devices achieved a final IOP < 21 mmHg in most participants (Hydrus microstent: 91.8%; iStent: 84%; RR 1.09, 95% CI 0.97 to 1.23; lowâcertainty evidence).
None of the participants who received the Hydrus microstent (N = 74) required additional glaucoma surgery; two participants who received the iStent (N = 76) did.
Few adverse events were found in either group.
No data were available on the proportion of participants achieving IOP less than 17 mmHg or 14 mmHg, or on HRQOL.
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Authors' conclusions:
In people with cataracts and generally mild to moderate OAG, there is moderateâcertainty evidence that the Hydrus microstent with cataract surgery compared to cataract surgery alone, likely increases the proportion of participants who do not require IOP lowering medication, and may further reduce IOP at shortâ and mediumâterm followâup.
There is moderateâcertainty evidence that the Hydrus microstent is probably more effective than the iStent in lowering IOP of people with OAG in the shortâterm.
Few studies were available on the effects of the Hydrus microstent, therefore the results of this review may not be applicable to all people with OAG, particularly in selected people with medically uncontrolled glaucoma, since IOP was controlled with medication in many participants in the included studies. Complications may be rare using the Hydrus microstent, as well as the comparator iStent, but larger studies are needed to investigate its safety
Diffuse Reflectance Spectroscopy of Epithelial Tissue with a Smart Fiber-optic Probe
Diffuse reflectance spectroscopy (DRS) with a fiber-optic probe can noninvasively quantify the optical properties of epithelial tissues and has shown the potential as a cost-effective, fast and sensitive tool for diagnosis of early precancerous changes in the cervix and oral cavity. However, current DRS systems are susceptible to several sources of systematic and random errors, such as uncontrolled probe-to-tissue pressure and lack of a real-time calibration that can significantly impair the measurement accuracy, reliability and validity of this technology as well as its clinical utility. In addition, such systems use bulky, high power and expensive optical components which impede their widespread use in low- and middle-income countries (LMICs) where epithelial cancer related death is disproportionately high. In this paper we report a portable, easy-to-use and low cost, yet accurate and reliable DRS device that can aid in the screening and diagnosis of oral and cervical cancer. The device uses an innovative smart fiber-optic probe to eliminate operator bias, state-of-the-art photonics components to reduce size and power consumption, and automated software to reduce the need of operator training. The device showed a mean error of 1.4 ± 0.5% and 6.8 ± 1.7% for extraction of phantom absorption and reduced scattering coefficients, respectively. A clinical study on healthy volunteers indicated that a pressure below 1.0 psi is desired for oral mucosal tissues to minimize the probe effects on tissue physiology and morphology
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