Investigation of Tethered System for Creating Artificial Gravity

Interplanetary journeys are long; taking anywhere between 6 months to a few years. Studies performed with astronauts in the various space missions have provided insights on adverse effects of microgravity on the human body. Artificial gravity provides a solution to keep humans healthy in such long duration interplanetary journey. Various designs have been studied to create artificial gravity, out of which, a tethered spinning system is the most promising due to its compact structure and ability to vary the radius of rotation. Though theoretically the most promising, little investigation has been done concerning the tethered system for artificial gravity. Speculative studies and some experiments on manned and unmanned missions have been done to analyze the rotating tethered system in Earth's orbit. These studies were performed in the Lower Earth Orbit. Such studies provide an excellent opportunity to speculate about the conditions during a trajectory to Mars. The primary purpose of this thesis is to investigate the amount of propellant required to spin the tethered system and tether materials, and also to find the deployment velocity on a trajectory to Mars. This system will increase the radius of rotation to reach a distance of 1 km from the center of rotation. To create artificial gravity, the capsules will be spun using thrusters till they reach a distance of 1 km each. This increase in the radius of rotation creates the need to investigate the amount of propellant to spin-up and spin-down (varying the radius of rotation), as well as the rate of deployment of the tether. Ion thrusters are selected to propel the capsules, because of its low thrust and better controllability. The propellant requirement is estimated using the rocket equation. Traditionally, the equation is used to determine the propellant required for long distances. In this thesis, we will use the same concept for a smaller change in velocity for the spin-up procedure. To find the amount of propellant required we have considered three scenarios in which the propellant could be used by incrementing energy, radius, and velocity in steps. The steps are crucial in determining the change in tangential velocities, and by extension mass of propellant required. A balance of deployment velocity and thruster engagement will ensure constant acceleration on the floor. The results from the simulation indicate that approximately 165 kg of fuel is required for the spin-up procedure when deployed at a gradually increasing rate, never exceeding 3 m/s. The deployment rate will help in ensuring humans in the capsules feel comfortable. This outcome will provide insight into the further investigation in the tethered system for controlled artificial gravity for human factors, tether material, and tether control. With growing interest in manned missions, an economical option needs to be investigated thoroughly. The outcome of this will provide insights on areas of further investigation to make the tethered system a reality

Research Journal of Pharmaceutical, Biological and Chemical Sciences Development and characterisation of oral fast dissolving tablet of nifedipine using camphor as a subliming material

ABSTRACT Mouth fast dissolving drug delivery system has gained high patient acceptability and popularity in the recent times. The aim of this study was to evaluate the effect of increasing nifedipine load on the characteristics of fast-disintegrating sublingual tablets for the potential emergency treatment of anginal pain and hypertension. Nifedipine undergoes first pass metabolism in liver and gut wall which has oral bioavailability of 43-77%. Sublingual dosage form bypasses the metabolism of the nifedipine in liver and offers a fast relieve from anginal pain and hypertension. An attempt has been made to prepare fast dissolving tablets of nifedipine were prepared by wet granulation technique using camphor as subliming agent and sodium starch glycolate together with crosscarmellose sodium as superdisintegrants, flavor and sweetner impart the taste to the formulation. The porous granules were compressed in to tablets by single punch tablet machine. Camphor was sublimed from the tablet by exposing to vacuum drier at 60°c for 12 hrs. All the formulations were evaluated for weight variation, hardness, friability, content uniformity, wetting time, disintegration time and dissolution rate. Among the formulations, (NEF6) one containing to be the best acceptable in terms of palatability, fast dissolving tablet having adequate strength. The disintegration time was found to be 58.0 ± 0.4 seconds, hardness of 3.4 ± 0.41 kg/cm2, wetting time of 39.3 ± 1.80 sec and drug release of 99.96% in 10 mins. All the formulations showed low weight variation. The present study demonstrated potentials for rapid absorption, improved bioavailability, effective therapy and patient compliance

Simultaneous Global Ionospheric Disturbances Associated With Penetration Electric Fields During Intense and Minor Solar and Geomagnetic Disturbances

A new observational phenomenon, named Simultaneous Global Ionospheric Density Disturbance (SGD), is identified in GNSS total electron content (TEC) data during periods of three typical geospace disturbances: a Coronal Mass Ejection-driven severe disturbance event, a high-speed stream event, and a minor disturbance day with a maximum Kp of 4. SGDs occur frequently on dayside and dawn sectors, with a ∼1% TEC increase. Notably, SGDs can occur under minor solar-geomagnetic disturbances. SGDs are likely caused by penetration electric fields (PEFs) of solar-geomagnetic origin, as they are associated with Bz southward, increased auroral AL/AU, and solar wind pressure enhancements. These findings offer new insights into the nature of PEFs and their ionospheric impact while confirming some key earlier results obtained through alternative methods. Importantly, the accessibility of extensive GNSS networks, with at least 6,000 globally distributed receivers for ionospheric research, means that rich PEF information can be acquired, offering researchers numerous opportunities to investigate geospace electrodynamics

Impact of liquid lipid on development and stability of trimyristin nanostructured lipid carriers for oral delivery of resveratrol

Nanostructured lipid carriers (NLCs) have emerged as versatile carriers to improve oral bioavailability of poorly water-soluble drugs as well as to protect labile drugs from degradation and metabolism. Prepared by blending solid and liquid lipids, the choice of liquid lipid can have a great influence on their physicochemical characteristics and stability. The present work investigated the impact of six different liquid lipids with diverse chemical structures and hydrophilic and lipophilic balance (HLBs) on the critical quality attributes (CQAs) and storage stability of NLCs with trimyristin as solid lipid. Resveratrol (RES) was used as model drug as its low water solubility, poor bioavailability, rapid metabolism and clearance from systemic circulation restricts its clinical use despite its wide spectrum of biological activities. Liquid lipids investigated included, two triglycerides, one medium chain (C8) glycerol tricaprylate (GTC) and second, long chain (C18) glyceryl trioleate (GTO); two propylene glycol fatty acid esters, propylene glycol monocaprylate (PGMC) and propylene glycol monolaurate (PGML); fatty acid ester decyl oleate (DO) and a PEGylated lipid polyethylene glycol-8 caprylic/capric glycerides (PCG). Box–Behnken experimental design was employed to ascertain the effect of four independent factors viz. type of liquid lipid, amount of liquid lipid, amount of drug and surfactant concentration and interactions between these factors on the CQAs of NLCs as response variables viz. particle size (PS), polydispersity index (PDI), zeta potential (ZP), drug encapsulation efficiency (EE), and drug loading (DL). The relationship between various factors and responses was established by response surface methodology (RSM). The oils with higher lipophilicity C18 triglycerides (GTO) and C18 fatty acid ester DO yielded NLCs with lower PS as compared to the oils with lower lipophilicity (PGC, PGMC and PGML). Although increasing the concentration of liquid lipids had an upward trend on the PS of NLCs, its PDI was more predominantly influenced by the nature of liquid lipid. The characteristic of the liquid lipid influenced the DL remarkably which varied from 2.94 to 7.56%. The ZP of nanoparticles varied from −21.3 to −39.9 mV with liquid lipids with free hydroxyl groups and higher HLB playing a more prominent role contributing to the increase in the negative surface charge. The characteristics of liquid lipid influenced the depression of melting point of RES with maximum distortion of the crystal lattice was caused by PGMC and least by GTO. The two, long chain oleates, DO and GTO exhibited a shift of lipid peak in NLCs to higher melting points (116 and 111 °C) than the less lipophilic liquid lipids (103–104 °C). The attributes of liquid lipid also discriminate whether the particle growth during storage followed Oswald's ripening or coalescence. NLC containing GTO exhibited the highest stability in terms of maintenance of the PS and particle size distribution at 20 °C. This study provides vital insight on impact of liquid lipids and future strategy for rational design of stable NLC systems for delivery of various bio-actives for drug delivery applications

NEW APPROACH TO CYCLOPHANES CONTAINING ETHYLENEOXY BRIDGE BY GLASER-EGLINTON COUPLING

Three strategies have been explored to generate cyclophane derivatives. In this regard, we identified alkyne metathesis, Diels-Alder reaction, and Glaser-Eglinton coupling as key steps. To this end, cyclophane derivatives containing ethyleneoxy bridge were successfully synthesized in four steps involving Glaser-Eglinton coupling and catalytic hydrogenation sequence

Diversity-oriented approach to cyclophanes via Claisen rearrangement and ring-closing metathesis as key steps

Among numerous reactions to prepare cyclophane derivatives, Claisen rearrangement reaction is very useful. We have prepared cyclophanes containing ethylene oxy bridge by double Claisen rearrangement reaction and ring-closing metathesis reaction as key steps. (C) 2014 Elsevier Ltd. All rights reserved

Diversity-Oriented Approach to Normuscopyridine and Its Analogues through Ring-Closing Metathesis

Ring-closing metathesis (RCM) is a useful protocol for assembling macrocycles. To synthesize normuscopyridine, and its analogues we used RCM as a key step in our strategy. Our approach to the synthesis of pyridine macrocycles involves two routes. The first approach starts with alkenylation of 2,6-bis[(phenylsulfonyl)methyl]pyridine and involves five steps with 10% overall yield. The second route begins with Grignard addition to pyridine-2,6-dicarbo nitrile, followed by RCM and one-pot removal of the carbonyl group before hydrogenation of the double bond in 28% overall yield. This approach has only three steps. Neither route involves the use of protecting groups. Various points of diversification are embedded in our strategy and eight different cyclophanes were assembled by adopting a general approach to these macrocyclics

Selected synthetic strategies to cyclophanes

In this review we cover various approaches to meta- and paracyclophanes involving popular reactions. Generally, we have included a strategy where the reaction was used for assembling the cyclophane skeleton for further functionalization. In several instances, after the cyclophane is made several popular reactions are used and these are not covered here. We included various natural products related to cyclophanes. To keep the length of the review at a manageable level the literature related to orthocyclophanes was not included