Pair-correlation properties and momentum distribution of finite number of interacting trapped bosons in three dimension

We study the ground state pair-correlation properties of a weakly interacting trapped Bose gas in three dimension by using a correlated many-body method. Use of the van der Waals interaction potential and an external trapping potential shows realistic features. We also test the validity of shape-independent approximation in the calculation of correlation properties.Comment: Accepted for publication in The Journal of Chemical Physic

Stability of attractive bosonic cloud with van der Waals interaction

We investigate the structure and stability of Bose-Einstein condensate of $^{7}$Li atoms with realistic van der Waals interaction by using the potential harmonic expansion method. Besides the known low-density metastable solution with contact delta function interaction, we find a stable branch at a higher density which corresponds to the formation of an atomic cluster. Comparison with the results of non-local effective interaction is also presented. We analyze the effect of trap size on the transition between the two branches of solutions. We also compute the loss rate of a Bose condensate due to two- and three-body collisions.Comment: 9 pages, 5 figure

DURATION DEPENDENT ANTIAPOPTOTIC EFFICACY OF CAMELLIA SINENSIS (GREEN TEA) ON STREPTOZOTOCIN INDUCED DIABETES LINKED TESTICULAR HYPOFUNCTION IN ALBINO RAT: GENOMIC AND FLOW CYTOMETRIC ASSESSMENT

Objective: The study has been conducted to search out the threshold duration of treatment of ethyl acetate fraction of methanolic extract of leaves of Camellia sinensis (L.) Kuntze at the dose of 100 mg/kg body weight for the management of diabetes-induced testicular impairment in streptozotocin-induced diabetic rat in a duration dependent fashion. Methods: In this respect, the glycemic, androgenic, oxidative stress sensors, gene expression of testicular androgenic key enzymes along with apoptotic markers were evaluated in a duration dependent way (14, 28 and 56 d). Results: A significant correction was noted in the levels of glycated haemoglobin (HbA1C), testicular thiobarbituric acid reactive substances (TBARS), conjugated diene (CD), sperm viability, sperm mitochondrial status, serum testosterone, and genomic expression of testicular Δ5, 3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD, Bax, Bcl-2 after treatment for different duration with the said fraction in diabetic groups in compare to respective vehicle-treated diabetic group without any toxicity induction in general. Thin layer chromatography (TLC) study of the fraction showed two spots with retention factors (Rf) of 0.78 and 0.51. Conclusion: The results showed that 28 d treatment was threshold duration of treatment for the correction of diabetes-induced testicular impairment

Growth defects in CrN/NbN coatings deposited by HIPIMS/UBM techniques

In recent years, high power impulse magnetron sputtering (HIPIMS) has caught the attention of users due to its ability to produce dense coatings. However, microscopic studies have shown that HIPIMS deposited coatings can suffer from some surface imperfections even though the overall number of defects can be significantly lower compared to, for example, arc deposited coatings of similar thickness. Defects can degrade the coating performance thus any kind of defect is undesirable. To better understand the nature of these imperfections and the science of their formation, three sets of chromium nitride/niobium nitride (CrN/NbN) coatings were deposited using HIPIMS technique combined with unbalanced magnetron sputtering (UBM) by varying the deposition parameters, i.e. deposition time (t = 15 to 120 min), bias voltage (Ub = - 40 to - 150 V) and chamber pressure (P = 0.2 to 1 Pa). For each set, one parameter was varied and other two were kept constant. All these experiments were carried out with chamber conditions close to those found in industrial environment. The study revealed that the generated defects were similar for all the coatings and with the increase in deposition time/bias voltage/chamber pressure the surface area covered by optically visible defects (surface defect density) was increased. These defects were categorised as flakes related defects (nodular, open void and cone-like defects) and defects associated with substrate pits (pinhole defects). Depending on their types, the defects influenced the corrosion and tribological properties of the coatings. As the origins of most defects were flakes (generated from the chamber components), an additional study was conducted to understand the influence of chamber cleanliness on defect generation. As expected, surface defect density of the coating produced in a comparatively clean chamber was reduced noticeably (from 3.18 % to 1.37 % after cleaning). Coatings with lower surface defects performed significantly well during corrosion and tribological tests. However, the comparison between pure UBM and combined HIPIMS/UBM deposited coatings suggested that along with the defects, coating structure also had a major role in corrosion, wear and friction mechanisms. Even for deposition conditions where HIPIMS coatings showed higher surface defects, owing to their microstructures, their corrosion resistance and tribological behaviour were superior to the UBM deposited coatings

Effect of substrate bias voltage on defect generation and their influence on corrosion and tribological properties of HIPIMS deposited CrN/NbN coatings

Substrate bias voltage is one of the most influential deposition parameter for physical vapour deposition processes as it can directly control the adatom mobility during coating growth. It influences the hardness, roughness as well as the microstructure of the coatings. Thus, bias voltage could also affect the defect formation during the coating deposition. High Power Impulse Magnetron Sputtering (HIPIMS) has been proven useful in producing void free and arc droplet free dense coatings. However, such coatings can still suffer from some defects associated with external factors (independent of deposition technique), such as substrate irregularities and the flakes coming from the chamber components. In order to study the effects of bias voltage (Ub) on the defect formation during HIPIMS process, four sets of CrN/NbN coatings were deposited at Ub = - 40 V, - 65 V, - 100 V and - 150 V. Microscopic studies revealed that with the increase in bias voltage the coatings morphology was altered and the percentage of surface area covered by optically visible defects was increased from 3.13 % to 4.30 %. The defects on the coatings deposited at Ub = - 100 V and - 150 V led to preferential corrosive attack resulting in a sharp increase in corrosion current density during Potentiodynamic polarisation experiments. Room temperature pin-on-disc tribological tests exhibited the influence of defects on the wear behaviour; however, the coefficient of friction (µ) values were mainly influenced by the nature of the oxides formed during the tests. Coating microstructure and bilayer thickness, along with the coating defects determined the coefficient of wear (Kc) values. This study revealed that the coating deposited at Ub = - 65 V had the highest wear resistance (Kc = 2.68 × 10-15 m3N-1m-1) and the lowest friction (µ = 0.48)

MGAT1 and Complex N-Glycans Regulate ERK Signaling During Spermatogenesis

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Destruction of attractive bosonic cloud due to high spatial coherence in tight trap

We study coherence of a trapped bosonic cloud with attractive finite-range interaction in a tight harmonic trap. One-body density and pair-distribution function in the ground state for different trap sizes are calculated. We also calculate healing length and the correlation length which signify the presence of high spatial coherence in a very tight trap leading to the destruction of the condensate for a fixed particle number. This is in marked variance with the usual collapse of the attractive metastable condensate when N > Ncr . Thus we investigate the critical frequency and critical size of the trap for the existence of attractive Bose-Einstein condensation. The finite-range interaction gives a nonlocal effect in the effective many-body potential, and we observe a high-density stable branch besides the known metastable branch. Moreover, the new branch shows universal behavior even in the very tight trap

Effect of chamber pressure on defect generation and their influence on corrosion and tribological properties of HIPIMS deposited CrN/NbN Coatings

It has been reported that compared to state-of-the-art technologies, High Power Impulse Magnetron Sputtering produces very dense and droplet free coatings due to the high plasma density and ionisation rate. However, thorough investigation of the coating morphology by Scanning Electron Microscopy, optical microscopy and other surface analysis methods revealed the existence of various types of coating defects. This study reports the influence of chamber pressure in particular on defect formation in CrN/NbN nanoscale multilayer coatings. The coating series was deposited using combined HIPIMS/UBM technique while varying the total chamber pressure from 0.2 Pa to 1 Pa. Four types of defects were identified, namely, nodular, open void, cone-like and pinhole. Defect density calculations showed that the coating produced at the lowest pressure, 0.2 Pa, had the lowest defect density of 0.84%. As expected coating corrosion properties improved linearly with decreasing defect density. Potentiodynamic polarisation corrosion studies revealed that in the potential range of - 300 mV to + 300 mV, the current density decreased with decreasing defect density (from 5.96% to 0.84%). In contrast, pin-on-disk tribology tests at room temperature demonstrated that the tribological properties of the coatings deposited at different chamber pressures were dependent on the crystallographic orientations and on the nature of the oxides formed at the tribological contact. Coatings with (200) crystallographic orientation had lower wear rates ( 1.6×10-15 m3N-1m-1) whereas coating with (111) crystallographic orientation had the highest wear rate (2.6×10-15 m3N-1m-1). Friction properties were influenced by the tribolayer formed during the tribological tests. However, for the coatings deposited at same chamber pressure of 0.35 Pa but with different defect densities (due to the difference in chamber cleanliness), the friction behaviour was directly influenced by the coating defects. The friction co-efficient (μ) decreased by a factor of two from 0.48 to 0.25 when the defect density decreased from 3.18% to 1.37%

Corrosion and Wear performances analysis of PVD CrMoN/Cr Coatings

Tools coated CrN based alloys are currently used in several industries for machining and manufacturing, but present severe wear, limiting their service life. Seeking an alternative, three CrMoN monolayers (~1µm in thickness) coatings with varying in the Mo percentage content were elaborated using the RF magnetron co-sputtering method. These coatings were evaluated and compared with the alloy currently used (CrN) by electrochemical tests in NaCl solution (stationary and no stationary method) and sliding wear tests (ball-on-disc configuration) performed at room temperature. The results indicate that the samples coated with CrMoN presented better performance against wear and corrosion than the uncoated sample. Among the coatings, the labeled C1 (27 % Mo) showed the best corrosion resistance as it presents a positive corrosion potential Ecorr. However, the best wear resistance (lowest coefficient of friction) was shown by coating labeled C4 (33 % Mo). All of the tested specimens underwent abrasive wear in addition to adhesive wear