Solid Freeform Fabrication of Functional Silicon Nitride Ceramics by Laminated Object Manufacturing 1

The processing of silicon nitride (Si3N4) structural ceramics by Laminated Object Manufacturing (LOM) using ceramic tape preforms was investigated. The key processing stages involved green shape formation (which used the LOM process), followed by the burnout of all organics, and final densification by pressureless sintering. Two material systems were considered. These were a) monolithic Si3N4 and b) a preceramic polymer infiltrated Si3N4. The raw materials for the process were tape preforms of Si3N4, which were fabricated by standard tape casting techniques. Mechanical property data obtained for the LOM processed Si3N4 showed high strength and fracture toughness values. The room temperature and high temperature (1260 o C) flexural strengths were in the range of 700-900 MPa and 360-400 MPa, respectively. The fracture toughness averaged from 5.5-7.5 MPa.m1/2. These strength and fracture toughness values are comparable to those reported for conventionally prepared Si3N4 ceramics. Thus, this research demonstrated that the LOM technique is a viable method for preparing functional Si3N4 ceramics with good physical and mechanical properties.Mechanical Engineerin

Pm(III), Eu(III), Tb(III), Pd(II), Pt(II) & Ir(II) Complexes of Picramic Acid

470-47

Contributions to the theory of generalised hypergeometric series

This thesis deals with various aspects of development in the field of both ordinary and basic hypergeometric functions. It comprises six chapters. The first chapter gives a brief survey of some of the recents developments in this field including the work done in the present thesis. The second chapter gives a systematic study of the transformations connected with the partial sums of generalised hypergeometric series, both ordinary and basic. The main theorem proved in the chapter gives the most general relation of its type. The third chapter is concerned with the development of the transformation theory of bilateral cognate trigonometrical series and generalises all the known results in that field. The fourth chapter gives the integral analogues of some of the transformations of basic series analogous to those for the ordinary series in Chapter VI of Bailey's Cambridge Tract. The fifth chapter deals with a systematic classification and study of two and three term relations between special kinds of well-poised series of the type and gives a new method, by integrals, of deducing these transformations easily. The last and the sixth chapter gives a number of identities involving basic analogues of Appell's hypergeometric functions of two variables and some associated functions.<p

Fused Deposition of Ceramics (FDC) for Structural Silicon Nitride Components

Fused Deposition of Ceramics is aI! SFF tec~que based on comm~rcial FDMTM ~echno.logy, f?r fabrication of structural and functIonal cerannc components. ThIS study descnbes, ill detail, process improvements made in pre-FDC, FDC, and post-FDC fabrication steps to achieve functional properties in commercial GS-44 silicon nitride ?omponents. . Microstructural characterization of sintered FDC parts reveals microstructures simllar to convennonally processed silicon nitride material. Mechanical properties of FDC processed silicon nitride bend bars and toughness samples were evaluated. These property evaluation studies demonstrate that mechanical properties similar to commercial GS-44 silicon nitride materials can be achieved using FDC. The study also describes results achieved on fabrication of complex components from silicon nitride using FDC.Mechanical Engineerin

Structural Ceramics by Fused Deposition of Ceramics

Fused Deposition of Ceramics (FDC) is a SFF technique, based on FDMTM technology, for fabrication of advanced structural ceramics from powderlbinder filaments. In this study, in-situ reinforced (ISR) Si3N4 powder and polymer/wax based binder systems were used as filament material for FDC processing using a commercially available FDMTM system, 3D Modeler. Powderlbinder feedstocks were mixed using a torque rheometer and filaments were fabricated using a capillary rheometer and twin screw extruder. Green FDC components were built from these filaments and then characterized for inter-road and inter-layer bonding. Binder removal procedures were established for FDC green components to yield brown parts without distortion or shape change. Brown FDC parts were characterized for carbon residue, pore distribution and dimensional changes. Brown FDC parts were then sintered and the sintered density, microstructure, and shrinkage anisotropy were studied.Mechanical Engineerin

Cloning and heterologous expression of a gene encoding lycopene-epsilon-cyclase, a precursor of lutein in tea (Camellia sinensis var assamica)

This report describes the cloning and expression of a gene lycopene epsilon cyclase, (LCYE) from Camellia sinensis var assamica which is a precursor of the carotenoid lutein in tea. The 1982 bp cDNA sequence with 1599 bp open reading frame of LCYE was identified from an SSH library constructed for quality trait in tea. 5’ and 3’ RACE (rapid-amplification of cDNA ends) was done to clone the full length cDNA of LCYE. Homology studies showed that the deduced amino acid sequence of LCYE gene had the highest sequence identity of up to 84% with Vitis vinefera. The cloned gene was successfully expressed in a PET based Escherichia coli expression system. The size of the expressed protein was 59615 Daltons. A suppression subtractive library was constructed using a quality clone H3111 (tester) and a garden series clone T3E3 (driver).Key words: Carotenoid, RACE, heterologous expression, lutein, tea

The high voltage system for the novel MPGD-based photon detectors of COMPASS RICH-1

The architecture of the novel MPGD-based photon detectors of COMPASS RICH-1 consists in a large-size hybrid MPGD multilayer layout combining two layers of Thick-GEMs and a bulk resistive MICROMEGAS. Concerning biasing voltage, the Thick-GEMs are segmented in order to reduce the energy released in case of occasional discharges, while the MICROMEGAS anode is segmented in pads individually biased at positive voltage, while the micromesh is grounded. In total, there are ten different electrode types and more than 20000 electrodes supplied by more than 100 HV channels. Commercial power supply units are used. The original elements of the power supply system are the architecture of the voltage distribution net, the compensation, by voltage adjustment, of the effects of pressure and temperature variation affecting the detector gain and a sophisticated control software, which allows to protect the detectors against errors by the operator, to monitor and log voltages and current at 1 Hz rate and to automatically react to detector misbehaviors. The HV system and its performance are described in detail as well as the electrical stability of the detector during the operation at COMPASS.Comment: 5th international conference on Micro-Pattern Gas Detectors (MPGD2017),presentation by Silvia Dalla Torr