The effect of gravity and temperature gradients on precipitation in immiscible alloys

The structure of immiscible alloys depends on the temperature gradient and the gravity force during solidification. The temperature gradient causes Marangoni movement of the droplets and the gravity force causes sedimentation or flotation of the droplets. In gradient experiments performed under normal and reduced gravity it is possible to distinguish between these two effects. This paper presents and analyses theoretically the results of experiments on Zn-Bi and Cu-Pb alloys, performed on earth and in the reduced gravity of space.     

Multi‐Step Crystallization of Self‐Organized Spiral Eutectics

A method for the solidification of metallic alloys involving spiral self‐organization is presented as a new strategy for producing large‐area chiral patterns with emergent structural and optical properties, with attention to the underlying mechanism and dynamics. This study reports the discovery of a new growth mode for metastable, two‐phase spiral patterns from a liquid metal. Crystallization proceeds via a non‐classical, two‐step pathway consisting of the initial formation of a polytetrahedral seed crystal, followed by ordering of two solid phases that nucleate heterogeneously on the seed and grow in a strongly coupled fashion. Crystallographic defects within the seed provide a template for spiral self‐organization. These observations demonstrate the ubiquity of defect‐mediated growth in multi‐phase materials and establish a pathway toward bottom‐up synthesis of chiral materials with an inter‐phase spacing comparable to the wavelength of infrared light. Given that liquids often possess polytetrahedral short‐range order, our results are applicable to many systems undergoing multi‐step crystallization.     

Decomposition of multiunit electromyographic signals

We have developed a comprehensive technique to identify single motor unit (SMU) potentials and to decompose overlapped electromyographic (EMG) signals into their constituent SMU potentials. This technique is based on one-channel EMG recordings and is easily implemented for many clinical EMG tests. There are several distinct features of our technique: 1) it measures waveform similarity of SMU potentials in the wavelet domain, which gives this technique significant advantages over other techniques; 2) it classifies spikes based on the nearest neighboring algorithm, which is less sensitive to waveform variation; 3) it can effectively separate compound potentials based on a maximum signal energy deduction algorithm, which is fast and relatively reliable; and 4) it also utilizes the information on discharge regularities of SMU's to help correct possible decomposition errors. The performance of this technique has been evaluated by using simulated EMG signals composed of up to eight different discharging SMU's corrupted with white noise, and also by using real EMG signals recorded at levels up to 50% maximum voluntary contraction. We believe that it is a very useful technique to study SMU discharge patterns and recruitment of motor units in patients with neuromuscular disorders in clinical EMG laboratories.     

Modelling the plane strain compression test to obtain constitutive equations of aluminium alloys

Hot plane strain compression tests on 1050, 1198, 3003 and 3004 aluminium alloys have been conducted. Based on these experiments and on a set of internal type constitutive equations for hot working, the values of the parameters in the constitutive functions are determined. The constitutive equations proposed here, with the constitutive functions and material parameters associated, accurately reproduce the basic tests. The procedure used to fit the material parameters is improved, in comparison with classical slip line analysis, by using a finite element modelling of the plane strain compression test. It is demonstrated that accurate plane strain or three-dimensional large strain finite element analysis can be used to correct the friction and lateral spread effects. Furthermore, it is demonstrated from comparison with the experimental observations that microstructural parameters can be accurately determined from numerical modelling. The constitutive equations and finite element procedure proposed here can be useful for obtaining an improved analysis of hot rolling of aluminium alloys.     

Antitumor Component(s) of Yogurt: Fractionation

Two methods of fractionation were employed to separate antitumor component(s) from yogurt. First, yogurt was separated by dialysis. Although feeding of the dialyzate fraction to mice inoculated with Ehrlich ascites tumor cells resulted in 32.9% inhibition of tumor cell counts and 23.5 to 26.3% reduction of deoxynucleic acid content of ascitic fluid, feeding of the yogurt retentate did not reduce tumor proliferation. Second, an aqueous fraction of yogurt was prepared by removal of the ether soluble matter. Administration of aqueous fraction at 2 mg/mouse intravenously resulted in 25.1 to 32.3% less cell growth whereas intraperitoneal inoculation resulted in only 15.0 to 15.9% reduced tumor proliferation. Antitumor activity may be due to a component(s) with a molecular weight ≤14,000, and it presumably is not bound chemically to any larger compound because it could be separated by dialysis.     

The use of immobilized enzymes in the food industry: a review.

The production of high fructose corn syrups was greatly facilitated by the use of immobilized glucose isomerase. Similarly, in Japan, the fermentation industry proved its processing efficiency for amino acids through the use of immobilized amino acid acylase. This article discusses the use of soluble enzymes in the food industry followed by a section on the various available methods to immobilize enzymes. Once enzymes are immobilized, many of their operational parameters could be altered. Rationale for the determination of the effects of immobilization is provided. A relatively new concept is the use of a single matrix for immobilizing more than one enzyme. Immobilized multi-enzyme systems offer many attractive advantages; however, such a process also raises some interesting questions about kinetics. These questions and their suggested answers are discussed in the penultimate section. The major emphasis of this article is on the use of immobilized enzymes in the food industry. Two systems--amino acylase and glucose isomerase--have been demonstrated to be techno-economically feasible. Immobilization of other enzymes, such as glucoamylase, lactase, protease, and flavor modifying enzymes, has received some attention. The potential of these new systems are also discussed.     

Peripheral Nerve unmyelinated axons following lumbar sympathectomy

One year after bilateral lumbar sympathectomy for Raynaud's syndrome, a young woman underwent fascicular biopsy of the sural nerve to help elucidate the cause of lower limb pain. The morphological features, density, and diameter spectrum of unmyelinated fibers were normal. The sympathetic nervous system appears to contribute few, if any, axons to the total population of unmyelinated axons in this cutaneous nerve.