Organosilicon reagents in natural product synthesis

Berzelius, the Swedish chemist in 1807 introduced the term 'org. compds.' as those substances derived from once living organisms. Carbon exhibits the property of catenation (formation of chains) and forms a plethora of compds. on earth. Silicon, which is placed below carbon in the periodic table, does not exhibit this property. A brief account of some of the several reagents and classes of compds. encountered in organosilicon chem. is presented

The concept of time in Buddhism

The present thesis is an attempt to expound the philosophical study of time in India. Its main purpose is to give a clear picture of the Buddhist notion of time as discussed in its different schools: the Pali tradition, Vaibhasikas (or the Sarvastivadins), Sautrantikas and the Madhyamikas. It also deals with the three major non-Buddhist systems: Nyaya-Vaisesika, Samkhya-Yoga and Jainism. The first chapter deals with the substantive reality of time in Nyaya-Vaisesika, which is a realistic and pluralistic system. It accepts time (mahakala) as an instrumental cause, eternal, absolute, independent, unique, infinite and all-pervading. According to this system, finite time (khandakala), such as second, minute, hour, day, past, present or future, has no independent status, and is only an imposed property of eternal time (kalopadhi). In the second chapter, Samkhya-Yoga gives a tremendous shock to absolute time of the Nyaya-Vaisesika. Whereas Samkhya identifies time with change, actions or events, Yoga ascribes reality to moment (ksana), but denies its aggregates as absolute time. In the third chapter, Jainism maintains that time is real and a substance, but it does not possess corporeality, though it has existence. It propounds the semi-realistic and atomistic theory of time. The fourth chapter makes an analysis of the concept of time in Pali Buddhism dispersed through a vast number of Pali texts. The fifth chapter deals with the important controversy on time between the Vaibhasikas (or the Sarvastivadins) and the Sautrantikas. The sixth and final chapter provides a Madhyamika critique of time. It is to be noted that in the entire Buddhist tradition time has never been considered as a reality, though we do find in it some interesting passages on the three time-epochs, the past, present and future, which are often taken as the modes of existence. But they too are in no sense real as such. The first appendix gives some different lists of computations of time maintained by different texts. This is in addition to the lists given by Nyaya-Vaisesika and Jainism. The second appendix is a new critical edition of the Prasannapada, chapter XIX, which demonstrates the Madhyamika critique of time

Steroids: a timeless fascination: cholesterol and its bio-​products

Steroids are solid org. compds. derived from all life forms, including microorganisms, plants and animals. They obtain their generic name 'steroids' from Greek: stereos = solid. Steroids encompass a wide variety of compds. of vital importance to life such as sterols, bile acids, sex hormones, anti-​inflammatory corticoid hormones, etc. Some of the important aspects of cholesterol, the principal sterol of higher animals are highlighted

The "non-intervention" policy in Spanish civil war

Thesis (M.A.)--Boston University, 1946. This item was digitized by the Internet Archive

On the stability of a four species syn eco-system with commensal prey-predator pair with prey-predator pair of hosts-III (2nd level prey-predator washed out states)

The present paper is devoted to an investigation on a Four Species (S1, S2, S3, S4) Syn Eco-System with Commensal Prey-Predator pair with Prey-Predator pair of Hosts (Both the Hosts are washed out states).  The System comprises of a Prey (S1), a Predator (S2) that survives upon S1, two Hosts S3 and S4 for which S1, S2 are Commensal respectively i.e., S3 and S4 benefit S1 and S2 respectively, without getting effected either positively or adversely.  Further S3 is Prey for S4 and S4 is Predator for S3.  The pair (S1, S2) may be referred as 1st level Prey-Predator and the pair (S3, S4) the 2nd level Prey-Predator.  The model equations of the system constitute a set of four first order non-linear ordinary differential coupled equations.  In all, there are sixteen equilibrium points.  Criteria for the asymptotic stability of three of these sixteen equilibrium points: 2nd  Level Prey-Predator Washed Out States are established.  The system would be stable if all the characteristic roots are negative, in case they are real, and have negative real parts, in case they are complex. The linearized equations for the perturbations over the equilibrium points are analyzed to establish the criteria for stability and the trajectories are illustrated.&nbsp

Embedded Piezoelectric Fiber Composite Sensors for Applications in Composite Structures

Health monitoring of the composite structures is an important issue that must be addressed. Embedded sensors could be an effective way to monitor the health of composite structures continuously and which could also avoid the catastrophic failures of composite structures. Piezoelectric-fiber-composite sensors (PFCS) made from micro-sized Lead Zirconate Titanate (PZT) fibers have great advantages over the traditional bulk PZT sensors for embedded sensor applications. PFCS as an embedded sensor will be an ideal choice to continuously monitor the stress/strain levels and health conditions of composites. This work presents a critical study on using PFCS as an effective embedded sensor within the composite structures. Firstly, a series of carefully planned experiments are conducted to study the sensor performance based on characteristics like transfer function, sensitivity, nonlinearity, resolution, and noise levels. A numerical simulation study is performed to understand the local stress/strain field near the embedded sensor region inside composite specimen. High stress-concentration regions are observed near the embedded sensor corner edge. In-plane tensile, in plane tension-tension fatigue, flexural, and short beam strength tests are performed to evaluate the strengths/behavior of the composites (composite laminates and composite sandwich structures) containing embedded PFCS sensor. Overall PFCS seems to have high compatibility with composites and the reduction in strength values are within the permissible limits. Embedded PFCS’s voltage output response under tension-tension fatigue loading conditions has been recorded simultaneously to study their ability to detect the changes in input loading conditions. A linear relationship has been observed between the changes in the output voltage response of the sensor and changes in the input stress amplitude. This means that by constantly monitoring the output response of the embedded PFCS, one could effectively monitor the magnitude of stress/strain acting on the structure. Experiments are also performed to explore the ability of the embedded PFCS to detect the damages in the structures using modal analysis and impact techniques. PFCS are able to detect defects like delamination and cracks inside the composite structure using these two methods. Hence embedded PFCS could be an effective method to monitor the health of the composite structures’ in-service conditions

Benchmarking Permutation Flow Shop Problem: Adaptive and Enumerative Approaches Implementations via Novel Threading Techniques

A large number of real-world planning problems are combinatorial optimization problems which are easy to state and have a finite but usually very large number of feasible solutions. The minimum spanning tree problem and the shortest path problem are some which are solvable through polynomial algorithms. Even though there are other problems such as crew scheduling, vehicle routing, production planning, and hotel room operations which have no properties such as to solve the problem with polynomial algorithms. All these problems are NP-hard. The permutation flow shop problem is also NP-hard problem and they require high computation. These problems are solvable as in the form of the optimal and near-optimal solution. Some approach to get optimal are exhaustive search and branch and bound whereas near optimal are achieved annealing, Genetic algorithm, and other various methods. We here have used different approach exhaustive search, branch and bound and genetic algorithm. We optimize these algorithms to get performance in time as well as get the result closer to optimal. The exhaustive search and branch and bound gives all possible optimal solutions. We here have shown the comparative result of optimal calculation for 10 jobs with varying machine number up to 20. The genetic algorithm scales up and gives results to the instances with a larger number of jobs and machines

Characterization of composite piezoelectric materials for smart joint applications

Piezoelectric materials have the ability to provide desired transformation from mechanical to electrical energy and vice versa. When a mechanical force is applied to the piezoelectric material an electrical voltage is generated and when an electrical voltage is applied to the piezoelectric material it gets strained or deformed. Owing to these characteristics piezoelectric materials can be used as a sensor, an actuator, as well as a power generation unit. The high brittleness property of the original piezoelectric material is one of the major constraints in using them in the engineering applications. In order to overcome this disadvantage the composite piezoelectric materials were developed. The piezoelectric fiber composite product is flexible and can sustain the extensive deformation without being damaged, and is compatible with the composite structures’ processing procedure; which makes it, an ideal material to be used as an embedded sensor & a force actuator within the composite structures. The smart joint can be designed to have the piezoelectric materials embedded in them, the piezoelectric materials can detect the various loads that act on the composite joint and could provide the required counter-balancing force to the excitation forces acting on the joint; and thereby could reduce or even eliminate the effects of stress concentrations at the composite joint. A high stress concentration is one of the principal causes of structural failures. In this work our main objectives are to study the sensing and force generation capabilities of various commercially available composite piezoelectric configurations through series of experimentations and to compare their performances in order to use them in the smart joint applications. Firstly, the sensing capabilities of these products were investigated at various input frequencies and amplitudes of the dynamic loads. Secondly, the tensile and bending force generation capabilities of these products were inspected with respect to various input excitation voltages. The results of these experiments depict that the voltage signals generated from these products are proportional to amplitudes of mechanical movement, with good response at high frequency, even at micrometer deformation domain; but the force generation is relatively low under the current input conditions and configuration under study