Thermodynamic Analyses of Multiple Evaporators Vapor Compression Refrigeration Systems with R410A, R290, R1234YF, R502, R404A, R152A and R134A

KAPIL CHOPRA,V. SAHNI,R. S. MISHRA 대한설비공학회 2014 International Journal Of Air-Conditioning and Refr Vol.22 No.1

In this paper, comparative thermodynamic analysis of system-1 (multiple evaporators and compressorswith individual expansion valves) and system-2 (multiple evaporators and compressorswith multiple expansion valves) has been presented which is based on energy and exergy principles. The comparison of systems-1 and -2 using ecofriendly R410A, R290, R1234YF, R502,R404A, R152A and R134A refrigerants was done in terms of COP (energetic effciency), exergeticeffciency and system defect. Numerical model has been developed for systems-1 and -2 for ¯ndingout irreversibility and it was observed that system-2 is better system in comparison with system-1for selected refrigerants. It was also found that R152a shows better performances than otherconsidered refrigerants for both systems.

Effect of annealing temperature on the electrical and structural properties of V/p-GaN Schottky structures

Padma, R.,Nagaraju, G.,Rajagopal Reddy, V.,Choi, Chel-Jong Elsevier 2016 THIN SOLID FILMS - Vol.598 No.-

<P><B>Abstract</B></P> <P>The electrical and structural properties of V/p-GaN Schottky barrier diode (SBD) have been investigated as a function of annealing temperature. The Schottky barrier height (SBH) of the as-deposited contact is found to be 0.82eV (<I>I–V</I>) and 1.10eV (<I>C–V</I>). However, it is noted that the SBH increases for the contact annealed at 400°C and the values are 0.94eV (<I>I–V</I>) and 1.21eV (<I>C–V</I>). Further, with increasing annealing temperature up to 500°C, the SBH decreases to 0.92eV (<I>I–V</I>) and 1.19eV (<I>C–V</I>). Also, the rectification ratio of the V/p-GaN SBD is evaluated for as-deposited and annealed contacts. The electrical parameters of the V/p-GaN SBD are also discussed with Cheung's and Norde functions. It is noted that the interface state density decreases upon annealing at 400°C and then slightly increases after annealing at 500°C. Results reveal that the superior electrical characteristics are obtained for the contact annealed at 400°C. The electrical results are also correlated with the interfacial microstructure of the contacts. The AES and XRD results reveal that the formation of nitride phases at the interface may be the reason for the increase of SBH after annealing at 400°C. The formation of gallide phases at the interface may be reason for the decrease in the SBH.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Annealing effects on electrical and structural properties of V/p-GaN SBD are studied. </LI> <LI> Maximum barrier height is obtained on V/p-GaN SBD upon annealing at 400°C. </LI> <LI> Interface state density decreases with increasing annealing temperature up to 400°C. </LI> <LI> Electrical results are correlated with the interfacial microstructure of the contacts. </LI> <LI> Nitride interfacial phases are responsible for increase in BH after annealing at 400°C. </LI> </UL> </P>

The sdB pulsating star V391 Peg and its putative giant planet revisited after 13 years of time-series photometric data

Silvotti, R.,Schuh, S.,Kim, S.-L.,Lutz, R.,Reed, M.,Benatti, S.,Janulis, R.,Lanteri, L.,Østensen, R.,Marsh, T. R.,Dhillon, V. S.,Paparo, M.,Molnar, L. Springer-Verlag 2018 Astronomy and astrophysics Vol.611 No.-

<P>V391 Peg (alias HS 2201+2610) is a subdwarf B (sdB) pulsating star that shows both <I>p</I>- and <I>g</I>-modes. By studying the arrival times of the <I>p</I>-mode maxima and minima through the O-C method, in a previous article the presence of a planet was inferred with an orbital period of 3.2 years and a minimum mass of 3.2 <I>M</I>Jup. Here we present an updated O-C analysis using a larger data set of 1066 h of photometric time series (~2.5× larger in terms of the number of data points), which covers the period between 1999 and 2012 (compared with 1999-2006 of the previous analysis). Up to the end of 2008, the new O-C diagram of the main pulsation frequency (<I>f</I>1) is compatible with (and improves) the previous two-component solution representing the long-term variation of the pulsation period (parabolic component) and the giant planet (sine wave component). Since 2009, the O-C trend of <I>f</I>1 changes, and the time derivative of the pulsation period (<I>p</I><SUP>.</SUP>) passes from positive to negative; the reason of this change of regime is not clear and could be related to nonlinear interactions between different pulsation modes. With the new data, the O-C diagram of the secondary pulsation frequency (<I>f</I>2) continues to show two components (parabola and sine wave), like in the previous analysis. Various solutions are proposed to fit the O-C diagrams of <I>f</I>1 and <I>f</I>2, but in all of them, the sinusoidal components of <I>f</I>1 and <I>f</I>2 differ or at least agree less well than before. The nice agreement found previously was a coincidence due to various small effects that are carefully analyzed. Now, with a larger dataset, the presence of a planet is more uncertain and would require confirmation with an independent method. The new data allow us to improve the measurement of <I>p</I><SUP>.</SUP> for <I>f</I>1 and <I>f</I>2: using only the data up to the end of 2008, we obtain <I>p</I><SUP>.</SUP>1 = (1.34 ± 0.04) × 10<SUP>−12</SUP> and <I>p</I><SUP>.</SUP>2 = (1.62 ± 0.22) × 10<SUP>−12</SUP>. The long-term variation of the two main pulsation periods (and the change of sign of <I>p</I><SUP>.</SUP>1) is visible also in direct measurements made over several years. The absence of peaks near <I>f</I>1 in the Fourier transform and the secondary peak close to <I>f</I>2 confirm a previous identification as <I>l</I> = 0 and <I>l</I> = 1, respectively, and suggest a stellar rotation period of about 40 days. The new data allow constraining the main <I>g</I>-mode pulsation periods of the star.</P>

GMR Effect in Co-Cu Microwires

V. Zhukova,J. J. del Val,M. Ilyn,M. Ipatov,R. Varga,C. Garcia,A. Zhukov 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.12

We studied magnetic properties and GMR effect of Cox − Cu100−x (10 ≤ x30 at%) microwires. We observed considerable magnetoresistance (MR), ΔR/R, in Co-Cu glass coated microwires withx = 10-30%. For low x content (x = 10), ΔR/R we observed negative MR, tending to saturate inhigh magnetic fields, H. On the other hand, for the samples x = 30 ΔR/R(H) dependences showednon-monotonic behavior, exhibiting R/R increase with H at low H-values (up to 5 kOe) and alsoconsiderable GMR effect. Temperature dependence of magnetization measured in samples cooled without magnetic field(zero field cooling, ZFC) and cooled under magnetic field (field cooled, FC) exhibit significantdifference for Cox Cu100−x (x = 30). For Cox Cu100−x (x = 10) microwires we observed a maximumat quite low temperature, indicating possibility of existence of some amount of small Co-grains. X-ray diffraction (XRD) results reveal that the structure of the metallic core is granular withtwo phases: the main one, fcc Cu (lattice parameter 3.61 °A), found in all samples and fcc -Co(lattice parameter 3.54 °A) which is present in microwires with higher Co content. In the case oflow Co content, XRD indicates that Co atoms are distributed within the Cu crystals. The quantityand the crystallite size of the formed phases strongly depend on the geometry of the microwire.

Charged-particle nuclear modification factors in PbPb and pPb collisions at s N N = 5.02 $$ \sqrt{s_{\mathrm{N}\;\mathrm{N}}}=5.02 $$ TeV

Khachatryan, V.,Sirunyan, A. M.,Tumasyan, A.,Adam, W.,Asilar, E.,Bergauer, T.,Brandstetter, J.,Brondolin, E.,Dragicevic, M.,Erö,, J.,Flechl, M.,Friedl, M.,Frü,hwirth, R.,Ghete, V. M.,Hartl, C. Institute of Physics Pub 2017 The journal of high energy physics Vol.2017 No.4

<P>The spectra of charged particles produced within the pseudorapidity window vertical bar eta vertical bar < 1 at root s(NN) = 5 : 02 TeV are measured using 404 mu b(-1) of PbPb and 27.4 pb(-1) of pp data collected by the CMS detector at the LHC in 2015. The spectra are presented over the transverse momentum ranges spanning 0 : 5 < p(T) < 400 GeV in pp and 0 : 7 < p(T) < 400 GeV in PbPb collisions. The corresponding nuclear modification factor, R-AA, is measured in bins of collision centrality. The R-AA in the 5% most central collisions shows a maximal suppression by a factor of 7-8 in the p(T) region of 6-9 GeV. This dip is followed by an increase, which continues up to the highest p(T) measured, and approaches unity in the vicinity of p(T) = 200 GeV. The R-AA is compared to theoretical predictions and earlier experimental results at lower collision energies. The newly measured pp spectrum is combined with the pPb spectrum previously published by the CMS collaboration to construct the pPb nuclear modification factor, R-pA, up to 120 GeV. For p(T) > 20 GeV, R-pA exhibits weak momentum dependence and shows a moderate enhancement above unity.</P>

Structural and optical properties of vanadium doped SnO₂ nanoparticles with high photocatalytic activities

Reddy, Ch.V.,Babu, B.,Vattikuti, S.V.P.,Ravikumar, R.V.S.S.N.,Shim, J. Elsevier [etc.] 2016 Journal of luminescence Vol.179 No.-

Vanadium (0.01, 0.03 and 0.05mol%) doped SnO<SUB>2</SUB> nanoparticles have been synthesized using combustion synthesis method. The as-prepared nanoparticles were characterized using various measurements such as XRD, SEM with EDS, HRTEM, Raman spectroscopy, optical, PL, XPS and FT-IR techniques. The crystal structure and average particle sizes of the prepared nanoparticles were confirmed from the XRD. The average crystalline particle sizes were decreased by increasing the vanadium dopant concentration. The presence of vanadium as V<SUP>4+</SUP> species in the host lattice was confirmed by X-ray photoelectron spectroscopy. The band gap energies were decreased by increasing dopant concentration. The 0.05mol% doped sample showed higher photocatalytic activity than undoped, V-1 and V-3 in decomposing rhodamine B (RhB) under UV light irradiation. The Raman and IR spectra confirm the fundamental vibration of SnO<SUB>2</SUB> host molecules.

Electrochromic performance of the mixed V₂O₅-WO₃ thin films synthesized by pulsed spray pyrolysis technique

Patil, C.E.,Tarwal, N.L.,Jadhav, P.R.,Shinde, P.S.,Deshmukh, H.P.,Karanjkar, M.M.,Moholkar, A.V.,Gang, M.G.,Kim, J.H.,Patil, P.S. Elsevier 2014 Current Applied Physics Vol.14 No.3

Vanadium pentoxide (V<SUB>2</SUB>O<SUB>5</SUB>) mixed tungsten trioxide (WO<SUB>3</SUB>) thin films have been synthesized by a novel pulsed spray pyrolysis technique (PSPT) on glass and fluorine doped tin oxide (FTO) coated glass substrates at 400 <SUP>o</SUP>C. Aqueous solutions of equimolar vanadium chloride and ammonium tungstate were mixed in volume proportions (5%, 10% and 15%) for the deposition of V<SUB>2</SUB>O<SUB>5</SUB>-WO<SUB>3</SUB> thin films. The structural, morphological, optical and electrochemical properties of V<SUB>2</SUB>O<SUB>5</SUB>-WO<SUB>3</SUB> thin films were investigated by FT-IR, XRD, SEM, cyclic voltammetry, chronoamperometry and chronocoulometry techniques. The results showed that the electrochemical properties of V<SUB>2</SUB>O<SUB>5</SUB> were altered by mixing WO<SUB>3</SUB>. All the films exhibited cathodic electrochromism in lithium containing electrolyte (0.5 M LiClO<SUB>4</SUB> + propylene carbonate (PC)). Maximum coloration efficiency (CE) of about 49 cm<SUP>2</SUP> C<SUP>-1</SUP> was observed for the V<SUB>2</SUB>O<SUB>5</SUB> film mixed with 15% WO<SUB>3</SUB>. The electrochemical stability of the sample was examined and it was found to be stable up to 1000 cycles.

Electrochromic performance of the mixed V2O5eWO3 thin films synthesized by pulsed spray pyrolysis technique

C.E. Patil,N.L. Tarwal,P.R. Jadhav,P.S. Shinde,H.P. Deshmukh,J.D. Song,A.V. Moholkar,M.G. Gang,김진혁,P.S. Patil 한국물리학회 2014 Current Applied Physics Vol.14 No.3

Vanadium pentoxide (V2O5) mixed tungsten trioxide (WO3) thin films have been synthesized by a novel pulsed spray pyrolysis technique (PSPT) on glass and fluorine doped tin oxide (FTO) coated glass substrates at 400 C. Aqueous solutions of equimolar vanadium chloride and ammonium tungstate were mixed in volume proportions (5%, 10% and 15%) for the deposition of V2O5eWO3 thin films. The structural, morphological, optical and electrochemical properties of V2O5eWO3 thin films were investigated by FT-IR, XRD, SEM, cyclic voltammetry, chronoamperometry and chronocoulometry techniques. The results showed that the electrochemical properties of V2O5 were altered by mixing WO3. All the films exhibited cathodic electrochromism in lithium containing electrolyte (0.5 M LiClO4 þ propylene carbonate (PC)). Maximum coloration efficiency (CE) of about 49 cm2 C1 was observed for the V2O5 film mixed with 15% WO3. The electrochemical stability of the sample was examined and it was found to be stable up to 1000 cycles.

Catalytic performance of vanadia-doped titania-pillared clay for the selective catalytic oxidation of H₂S

Bineesh, K.V.,Kim, S.Y.,Jermy, B.R.,Park, D.W. Korean Society of Industrial and Engineering Chemi 2009 Journal of industrial and engineering chemistry Vol.15 No.2

A series of vanadia-doped titania pillared clay (V/Ti-PILC) with various amounts of vanadia were prepared and their performance for the selective catalytic oxidation of H<SUB>2</SUB>S was investigated in this study. V/Ti-PILCs were characterized using X-ray diffraction (XRD), BET apparatus, and X-ray photoelectron spectroscopy (XPS). V/Ti-PILCs showed better catalytic performance than as such Ti-PILC at temperatures ranging from 220 to 300<SUP>o</SUP>C without any considerable SO<SUB>2</SUB> emission. The H<SUB>2</SUB>S conversion over V/Ti-PILC increased with increasing vanadia content up to 5wt.%. This superior catalytic performance might be related to the uniform dispersion of vanadia in the form of monomeric and polymeric species. However, it decreased at 10wt.% vanadia loading due to the decrease of surface area and to the formation of crystalline V<SUB>2</SUB>O<SUB>5</SUB> phase. The presence of water vapor in the reactant mixture resulted in the decrease of the H<SUB>2</SUB>S conversion.

Thermosensitive nasal in situ gelling systems of rufinamide formulated using modified tamarind seed xyloglucan for direct nose-to-brain delivery: design, physical characterization, and in vivo evaluation

Dalvi Avantika V.,Ravi Punna R.,Uppuluri Chandra T.,Mahajan Radhika R.,Katke Sumeet V.,Deshpande Vibha S. 한국약제학회 2021 Journal of Pharmaceutical Investigation Vol.51 No.2

Purpose Rufinamide is an anti-epileptic drug approved for use in children ≥ 4 years of age and in adults. It is marketed as Banzel in the USA. In 2015, Banzel received approval for use in pediatric patients (1–4 years of age) and the patent for which expires in 2023. It suffers from poor oral bioavailability, and hence, small amounts of the drug reach the brain. This has led to high and frequent dosage administration of rufinamide. This work aims to improve its brain bioavailability by formulating a nasal thermosensitive in situ gel using xyloglucan. Methods The formulation was optimized using rheometric analysis, texture analysis, in vitro, and in vivo studies. Pharmacokinetic studies in rats were carried out to assess direct nose to brain uptake for the optimized in situ gelling formulation of rufinamide and compared with intravenous bolus and aqueous nasal suspension of rufinamide. Finally, brain targeting indices % DTE, and % DTP were calculated. Results All the formulations showed gelation below 35 °C. The final formulation comprised 2.0% w/v xyloglucan, 0.01% v/v thiomersal (preservative), and rufinamide in suspended form. The %DTE values for the in-situ gel formulation and aqueous suspension were 1069.94 and 146.88, and the %DTP values were 90.65 and 31.91, respectively. Conclusion This work demonstrated the superiority of the nasal gel formulation over oral formulation of rufinamide. If translated to humans, this would definitely help patients suffering from epilepsy, especially pediatric population, in whose case, a high dose and frequent dosage administration via oral route is inconvenient.