In-focus electron microscopy of frozen-hydrated biological samples with a Boersch phase plate

We report the implementation of an electrostatic Einzel lens (Boersch) phase plate in a prototype transmission electron microscope dedicated to aberration-corrected cryo-EM. The combination of phase plate, C_s corrector and Diffraction Magnification Unit (DMU) as a new electron-optical element ensures minimal information loss due to obstruction by the phase plate and enables in-focus phase contrast imaging of large macromolecular assemblies. As no defocussing is necessary and the spherical aberration is corrected, maximal, non-oscillating phase contrast transfer can be achieved up to the information limit of the instrument. A microchip produced by a scalable micro-fabrication process has 10 phase plates, which are positioned in a conjugate, magnified diffraction plane generated by the DMU. Phase plates remained fully functional for weeks or months. The large distance between phase plate and the cryo sample permits the use of an effective anti-contaminator, resulting in ice contamination rates of <0.6 nm/h at the specimen. Maximal in-focus phase contrast was obtained by applying voltages between 80 and 700 mV to the phase plate electrode. The phase plate allows for in-focus imaging of biological objects with a signal-to-noise of 5-10 at a resolution of 2-3 nm, as demonstrated for frozen-hydrated virus particles and purple membrane at liquid-nitrogen temperature.     

Interactions of colloidal particles with complex ions and polymers

The lecture represented a review of the work done in the author’s laboratory dealing with the behavior of a variety of submicronic particles in the presence of simple and complex ions, surface active agents, polyelectrolytes and polymers. Experimentally, the stability of colloidal sols, which can be readily followed by optical methods, was investigated as a function of the composition of the electrolyte environments. This approach offers a number of advantages when the evaluation of solid-solute interactions is attempted. By selecting various colloidal sols one can study the interactions of counterions with particles of different surface properties, such as the charge density, type and concentration of stabilizing ions, degree of solvation, surface ionization, etc. One of five papers presented at the Symposium, “Basic Aspects of Detergency,” AOCS-ISF World Congress, Chicago, September 1970. This lecture summary was prepared during the author’s stay at the Swedish Institute for Surface Chemistry, Stockholm.     

Stage I ovarian cancer by transvaginal color Doppler sonography: a report of 18 cases

PURPOSE: To evaluate the tolerability and 24 hours efficacy of a new anti-hypertensive drug: cilazapril. METHODS: In an open non comparative study 20 hypertensive patients (16 females, age from 30 to 60 years, average = 49.4) were followed for 6 weeks: 2 wash out and 4 treatment (5 mg OD). Blood pressure (BP) was measured by casual and ambulatory blood pressure monitoring (ABPM) readings. RESULTS: Comparing washout and treatment periods, ABPM averages both for systolic and diastolic BP (mmHg) showed significant decrease in 24 hours, during day and night sub periods. The decrease was not significant between averages considering the "early morning rising pressure" sub period. Heart rate averages showed significant reduction at all sub periods except during night. Adverse effects were mild and resolved spontaneously (n = 3, 15%). CONCLUSION: Cilazapril seems to be efficacious as antihypertensive. Tolerability is excellent. It preserved circadian rhythm despite significantly reducing blood pressure at all periods evaluated except early morning. A bradycardic effect observed mostly during day period should be better evaluated.     

A robust Smith predictor modified by internal models forintegrating process with dead time

The internal model principle and control together (IMPACT) structure of the Smith predictor is proposed. The structure constructively achieves both the robust stability and absorption of external disturbances. In the structure design, the absorption principle is applied to enable the rejection of arbitrary class of deterministic disturbances and/or to suppress the effects of low frequency stochastic external signals on the system output. It is shown that the tuning of IMPACT structure is extremely simple due to relatively small number of tuning parameters all having clear physical meanings. The presented results of the simulation runs demonstrate the design procedure and illustrate the efficiency of the structure in disturbance absorption     

Micro-abrasion resistance of thermochemically treated steels in aqueous solutions: Mechanisms, maps, materials selection

The area of micro-abrasion is an interesting and relatively recent area in tribo-testing methodologies, where small particles of less than 10 μm are employed between interacting surfaces. It is topical for a number of reasons; its direct relation to the mechanisms of the wear process in bio-tribological applications, ease in conducting tests and the good repeatability of the test results. It has widespread applications in conditions used in the space and offshore industries to bio-engineering for artificial joints and implants.There have been many recent studies on the micro-abrasion performance of materials, ranging from work basic metals to nano-structured coatings. However, no significant work is reported on the micro-abrasion resistance of thermochemically treated steels. Hence, this paper looks at the performance of two thermochemically treated steels, Tenifer bath nitride stainless steel (T-SS) and vanadized carbon steel (V-CS) in such conditions with reference to the stainless steel (SS) by varying the applied load and sliding distance.The results indicated that T-SS demonstrates exceptionally poor resistance to micro-abrasion. It was observed that the heat treatment process and properties of the hardened layer (hardness and thickness) are extremely important in determining the micro-abrasion resistance of such steels. Finally, the results were used to develop micro-abrasion mechanism and wastage maps, which can be used to optimize the surface treated materials for micro-abrasion resistance.     

Mars Pathfinder Microrover

When the Mars Pathfinder (MPF) spacecraft lands on Mars, the Microrover Flight Experiment (MFEX) will be deployed and perform its mission to conduct technology experiments verifying the engineering design, to deploy an alpha proton x-ray spectrometer (APXS) to measure elemental properties of rocks and soil, and to image the MPF lander. In accomplishing this mission the MFEX rover must determine a safe path to goal locations traversing over a poorly known Martian surface. The rover does this mission with a capable mobile platform executing on-board autonomous functions of navigation and hazard avoidance. In this paper we describe the rover, its operational environment and the implementation of the on-board autonomous functions.     

Application of Aberration-Corrected TEM and Image Simulation to Nanoelectronics and Nanotechnology

The image quality in electron microscopy often suffers from lens aberration. As a result of lens aberrations, critical information appears distorted at the atomic scale in high-resolution transmission electron microscopy (HRTEM). In scanning TEM (STEM), the spatial resolution of images and the quality of spectroscopic data are greatly reduced. With the recent introduction of aberration-corrected lenses and monochromators, new and exciting images with sub-0.1-nm spatial resolution are now recorded routinely, and electron energy loss data has been used to determine the location of a single atom in an atomic column. As a result of the decreased focal depth of an aberration-corrected lens used in STEM, the dream of three-dimensional (3-D) atomic resolution is one step closer and for HRTEM it was shown that 3-D imaging with atomic resolution is feasible. However, understanding imaging and spectroscopy in HRTEM and STEM still requires refined modeling of the underlying electron scattering processes by multislice image simulation. Since research into the physics and technology of nanoelectronic devices has already moved into sub-10-nm transistor gate lengths, the need for well-understood imaging and spectroscopy at nanoscale dimensions is already upon us. Fortunately, nanowires and other nanotechnology materials serve as useful test samples as well as being potential materials for future nanoelectronics. This enables early development of microscopy methods that will be used to investigate future generations of integrated circuits     

Control of Selective-Collective Elevators Based on the Use of Integrated Circuits

Selective-collective elevators present, as far as the logic design is concerned, the most complex control problems among simplex elevators. A control unit for this type of elevator, completely based on the use of digital integrated circuits, is described in the paper. The application of integrated circuits improves, in the authors' opinion, reliability and maintainability of elevator control as compared with the classical control units equipped with electromechanical relays and even more recent static solutions with discrete transistor logic circuits. This approach gives not only technical advantages, but is also justified from the economic point of view. The developed elevator control has been constructed and tested successfully on a six-floor office building. Owing to the conception of the functional subunits, it is possible to build up controls for any number of floors using only five standard printed circuit boards. The design of the control unit is based on the combinational and asynchronous sequential logic circuits. The Boolean equations, according to which the subunits were implemented, are given in the paper.     

Energy-efficiency analyses of heterogeneous macro and micro base station sites

Due to the introduction of newer technologies like Long Term Evolution (LTE) in already deployed cellular access networks, changes in the energy-efficiency of networks consisting predominantly of macro base station sites (BSSs) can be expected. An investigation has been performed for two prominent energy metrics of cellular networks: Power per Unit Area (PUA) and Energy per bit and Unit Area (EbUA). Analytical relations have been developed that express the influence of parameters such as BSs’ transmit (Tx) powers, inter-site distances (ISDs), and a number of heterogeneous macro or LTE micro BSSs on the PUA and EbUA. It has been shown that appropriate selection of these parameters can ensure significant energy savings. Besides the possibility of finding an optimal trade-off among ISDs and Tx powers of macro BSSs, which will minimize PUA and maximize EbUA, adding micro LTE BSs to such heterogeneous networks contributes to the improvement of network energy efficiency.