Showing papers on "Microscale chemistry published in 1992"

Heat Transfer Regimes in Microstructures

Abstract: Submicron dimensions are the hallmark of integrated electronic circuits, photovoltaic cells, sensors, and actuators. The design of these devices requires heat transfer analysis. Often it is not known to the designer whether a given microstructure can be analyzed using macroscale heat transfer theory, i.e., a method not considering the size dependence of a transport property such as thermal conductivity. This study develops regime maps showing the boundary between the macroscale and microscale heat transfer regimes. The maps relate the geometric dimension separating the two regimes to temperature for conduction in solids, to temperature, pressure, and Reynolds number for convection in gases, and to the temperature of the emitting medium for radiative transfer. The material purity and defect structure strongly influence the regime boundaries. Microstructures pertaining to a given technology are marked on these maps to determine whether macroscale heat transfer theory is applicable. By marking regions on the maps for the expected future development of microtechnologies, research needs in microscale heat transfer can be anticipated.

Effect of microscale thermal conduction on the packing limit of silicon-on-insulator electronic devices

Abstract: It is pointed out that silicon-on-insulator (SOI) electronics have a buried silicon dioxide layer which inhibits device cooling and reduces the thermal packing limit, the largest number of devices per unit substrate area for which the device operating temperature is acceptably low. Thermal analysis yields the packing limit of SOI MOSFET devices in terms of the device power and the limit on the channel temperature. Thermal conduction is microscale if it is significantly reduced by the boundary scattering of heat carriers, electrons in aluminum, and phonons in silicon. If microscale effects are not considered, the packing limit is overpredicted by 22% for a substrate temperature of 300 K and 100% for substrate temperature of 77 K. >

Chemo-micromechanics of brittle solids

Abstract: A s imple micromechanical model is formulated for a brittle solid reacting with water-borne aggressive chemical substances Underlying physicochemical processes, diffusion, chemical reaction, expansion of reaction products and microcracking, are modeled on the microscale The microscale models are homogenized into a governing set of equations relating macrovariables of the problem Sulphate attack on concrete is used to illustrate the efficiency of the derived model

Method of producing metallic microscale cold cathodes

Abstract: Microscale cold cathodes include a metallic emitter tip with a very sharp end. The microscale cold cathodes are manufactured by forming a cone of metal on a substrate, oxidizing the surface of the cone, and removing the oxidized film from the cone surface to produce an emitter tip.

Microscale techniques for determination of magnetic susceptibility

Abstract: Theory, operation, and application of the MSB-1 balance, a new type of magnetic susceptibility balance.

Microscale reactions of vanillin

Abstract: In this paper five microscale experiments which allow first-year organic student sot study the properties and reactions of vanillin are presented.

Micromechanical Simulation of Thermo-Mechanical and Thermal Properties of Woven-Fabric Composites

Abstract: This paper presents some computational aspects of simulating effective orthotropic behavior of fabric reinforced composites through homogenization techniques. A finite element solution scheme is presented for solving the related microscale boundary value problems which arise in the homogenization scheme. The microscale is defined over a periodic unit cell in a plain-weave fabric reinforced composite. The complex geometry of the fabric weave presents some nontrivial challenges for the finite element modeling effort. In particular, appropriate boundary conditions for minimizing the computational effort are discussed by exploiting various symmetry and periodicity conditions of the unit cell.

Microscale distillation—Calculations and comparisons

Abstract: In this distillation experiment students perform both a simple and a fractional distillation using the microscale version of traditional glassware.

Microscale characterisation of epitaxial semiconducting homolayers. - II. Electron beam induced current

Abstract: 2014 The dependence of the electron beam induced current (EBIC) collection efficiency ~CC on the electron beam voltage is modelled for the particular case of the GaAs homostructure studied in part I of this paper. The minority carrier diffusion length L1 and the doping level ND1 of the uppermost layer, as well as the value of the first and second interface recombination velocities V1 and V2 can be determined by this technique. The experiments, performed on two homostructures, grown in the same conditions, on semi-insulating substrates supplied by different manufacturers, indicate the influence of the substrate on the value of L1 and ND1. Microsc. Microanal. Microstruct. DECEMBER 1992, PAGE 501 Classification Physics Abstracts 07.80 73.60B 73.40

The microscale organic laboratory: A very simple method of filtration and recrystallization

Abstract: The following inexpensive system can be used to perform filtration, washing and crystallization without the loss of product in an organic lab.

Microscale Coupling of Solidification and Flow

Abstract: Morphological instability is discussed via linear and nonlinear theories. Couplings with forced flows and convecting melts are discussed in terms of physical mechanisms and mathematical descriptions. Microscale evolutions of coupled phenomena involve the development of cells, and travelling waves, and the selection of patterns and scales.