Effect of rotation in lubrication problems: Existence of more fundamental solutions

AbstractA generalized Reynolds equation is derived in the present paper by taking into account the effect of rotation in lubrication problems. The existence of certain fundamental solutions is shown in this extended framework which is not allowed in the classical Reynolds theory. Results concerning the pressure and the load capacity of the resulting bearing system are obtained and interpreted in the respective cases when the film thickness is a linear or an exponential functions of the coordinate along the bearing length. One of the important results is that while the load capacity decreases with increasing values of α for an exponentially inclined slider in the classical Reynolds theory, it increases with increasing values of α in the present context

Salvaging the Thompson-Chandrasekhar criterion: A tribute to S. Chandrasekhar

AbstractThe sole surviving challenge in the linear theory of magnetothermoconvection, which emerges from an unsuccessful attempt of S. Chandrasekhar (Philos. Mag. 743 (1952)) and demands a mathematical proof of the existence of overstable motions when the boundaries are dynamically free and thermally and electrically perfectly conducting, is overcome herewith. As a consequence the linear theory, which prior to 1985 was mostly ridden with conjectures and controversies, is brought to a state of perfection where it is free from any such anomalies and a successful nonlinear investigation of magnetothermoconvection is a distinct possibility

Temperature and dissolved oxygen stratification in the lake Rudrasagar: Preliminary investigations

Temperature drives the major physico-chemical and biological actions in inland water bodies. The higher the water temperature, the greater the biogeochemical activity influenced by the environmental intrinsic and extrinsic parameters. Temperature also controls the dynamics of sustainability of various aquatic organisms that live in lakes and reservoirs, though higher life forms, such as fish, insects, zooplankton, phytoplankton, and other aquatic species all have a recommended temperature variety. The increase in water temperature due to the increase in atmospheric air temperature results in lake water column stratification and the dissolved oxygen level variation in aquatic systems are greatly affected. The vertical distributions of dissolved oxygen in the water column are highly dependent due to change in vertical temperature gradient. In the present paper, an effort has been made to investigate the impact of temperature stratification on dissolved oxygen variability in the Rudrasagar, a natural lake in western Tripura. The changes in dissolved oxygen distribution in this natural lake will give us an idea of regional lake health condition and will also establish the need of further large scale research concerning the development of a biophysical-coupled model

The economic synthesis of pyridinium fluorochromate(VI), C<SUB>5</SUB>H<SUB>5</SUB>NH[CrO<SUB>3</SUB>F] (PFC), and solvent-free oxidation of organic substrates with PFC

A 1:1:1 stoichiometric reaction among CrO3, aqueous HF and pyridine affords orange crystalline pyridinium fluorochromate(VI), C5H5NH[CrO3F] (PFC), in 99.2% isolated yield. The reagent under solvent-free conditions readily converts benzylic, secondary, and allylic alcohols to the corresponding carbonyls and selectively oxidizes secondary alcohols in the presence of primary alcohols, polycyclic hydrocarbons to cyclic ketones, benzoin to benzil, PPh3 to O=PPh3, methylphenyl sulfide to sulfoxide, cyclohexanone oxime to cyclohexanone, an allylic &#916;5-steroid to the corresponding &#945;,&#946;-unsaturated ketone and deprotects dioxolanes and dithiolanes to aldehydes; the economic synthesis of PFC, its ease of reaction without solvent, versatility, and high isolated yields of the products are the significant features of the protocol

Temperature and dissolved oxygen stratification in the lake Rudrasagar: Preliminary investigations

Temperature drives the major physico-chemical and biological actions in inland water bodies. The higher the water temperature, the greater the biogeochemical activity influenced by the environmental intrinsic and extrinsic parameters. Temperature also controls the dynamics of sustainability of various aquatic organisms that live in lakes and reservoirs, though higher life forms, such as fish, insects, zooplankton, phytoplankton, and other aquatic species all have a recommended temperature variety. The increase in water temperature due to the increase in atmospheric air temperature results in lake water column stratification and the dissolved oxygen level variation in aquatic systems are greatly affected. The vertical distributions of dissolved oxygen in the water column are highly dependent due to change in vertical temperature gradient. In the present paper, an effort has been made to investigate the impact of temperature stratification on dissolved oxygen variability in the Rudrasagar, a natural lake in western Tripura. The changes in dissolved oxygen distribution in this natural lake will give us an idea of regional lake health condition and will also establish the need of further large scale research concerning the development of a biophysical-coupled model.   Keywords: Thermal stratification, Dissolved Oxygen, Thermocline, Rudrasagar Lake, Hypolimnio

Solar Cycle Variation of 0.3-1.29 MeV/nucleon Heavy Ion Composition during Quiet Times near 1 AU in Solar Cycles 23 and 24

We report on the annual variation of quiet-time suprathermal ion composition for C through Fe using Advanced Composition Explorer (ACE)/Ultra-Low Energy Isotope Spectrometer (ULEIS) data over the energy range 0.3 MeV/nuc to 1.28 MeV/nuc from 1998 through 2019, covering solar cycle 23's rising phase through Solar Cycle 24's declining phase. Our findings are (1) quiet time suprathermal abundances resemble CIR-associated particles during solar minima; (2) quiet time suprathermals are M/Q fractionated in a manner that is consistent with M/Q fractionation in large gradual solar energetic particle events (GSEP) during solar maxima; and (3) variability within the quiet time suprathermal pool increases as a function of M/Q and is consistent with the analogous variability in GSEP events. From these observations, we infer that quiet time suprathermal ions are remnants of CIRs in solar minima and GSEP events in solar maxima. Coincident with these results, we also unexpectedly show that S behaves like a low FIP ion in the suprathermal regime and therefore drawn from low FIP solar sources.Comment: Accepted in Astrophysical Journal. 19 pages, 10 figures, 4 table

Open appendicectomy stump: invaginate or not to invaginate?

Acute appendicitis remains the most common abdominal surgical emergency. Appendicectomy is the standard treatment of acute appendicitis, which performed by open or laparoscopic approach. During open method, after removal of appendix, stump simple ligation or simple ligation and invagination. A prospective randomized study conducted at Smt SCL General Hospital, Smt NHL municipal Medical College, Ahmedabad between October 2009 to September 2011 to evaluate the necessity of appendicular stump invagination during appendicectomy. A total 110 patients were studied and randomized into two group, Group I stump simple ligation, transfixation and invagination and Group II stump simple ligation and transfixation only. There was no statically significant difference in the rate of postoperative complication and post operative hospital stay between the two groups. The mean operating time was significantly shorter in group without invagination. The rate of postoperative paralytic ileus was more in group I. We conclude that simple ligation of the appendicular stump during appendicectomy is safe, simple and shortens operating time

xCT-Driven Expression of GPX4 Determines Sensitivity of Breast Cancer Cells to Ferroptosis Inducers

Inducers of ferroptosis such as the glutathione depleting agent Erastin and the GPX4 inhibitor Rsl-3 are being actively explored as potential therapeutics in various cancers, but the factors that determine their sensitivity are poorly understood. Here, we show that expression levels of both subunits of the cystine/glutamate antiporter xCT determine the expression of GPX4 in breast cancer, and that upregulation of the xCT/selenocysteine biosynthesis/GPX4 production axis paradoxically renders the cancer cells more sensitive to certain types of ferroptotic stimuli. We find that GPX4 is strongly upregulated in a subset of breast cancer tissues compared to matched normal samples, and that this is tightly correlated with the increased expression of the xCT subunits SLC7A11 and SLC3A2. Erastin depletes levels of the antioxidant selenoproteins GPX4 and GPX1 in breast cancer cells by inhibiting xCT-dependent extracellular reduction which is required for selenium uptake and selenocysteine biosynthesis. Unexpectedly, while breast cancer cells are resistant compared to nontransformed cells against oxidative stress inducing drugs, at the same time they are hypersensitive to lipid peroxidation and ferroptosis induced by Erastin or Rsl-3, indicating that they are \u27addicted\u27 to the xCT/GPX4 axis. Our findings provide a strategic basis for targeting the anti-ferroptotic machinery of breast cancer cells depending on their xCT status, which can be further explored