The interfacial bond stress in steel fiber cement composites

In fiber cement composites most fibers are in a state of partial bond due to internal stresses arising from moisture migration during fabrication and subsequent volume changes in the matrix. A wide variation in the computed interfacial bond strength therefore occurs depending upon the type of test or when derived from phenomena such as crack spacing. In practice debonding of the fibers occurs in flexural tension in the presence of a strain gradient. This paper presents further data on steel fiber mortar and concrete to confirm the validity of the composite mechanics approach to predict the composite flexural strength. It is shown that the composition of the matrix and its strength properties influence the fiber-matrix interfacial bond stress and the relative contributions of the matrix and the fibers to the composite flexural strength.     

Persistent enhancement of potassium-induced responses of the rat vas deferens by desipramine

The effect of desipramine on the cumulative dose-response curves of noradrenaline and potassium (K+) was examined on the isolated rat vas deferens. An exposure of 10 min to 10(-7) M desipramine caused a leftward shift and an increase in the maximum response of cumulative dose-response curves of noradrenaline. Desipramine (10(-7) M), in contact with the tissue for 10 min, enhanced responses to cumulative additions of K+ without causing a consistent change in threshold concentrations. Wash-out of desipramine resulted in a rapid loss of enhanced maximum response to noradrenaline while the maximum response to K+ did not show any decrease for up to 120 min after wash-out of drug. One possible explanation for the persistent enhancement of K+-induced responses may be that desipramine causes postjuntional changes which selectively influence contractile responses of this tissue to K+.     

New technique for designing nearly orthogonal wavelet filter bankswith linear phase

A new technique based on nonlinear optimisation to design nearly orthogonal wavelet filter banks with linear phase is proposed. The main idea is to impose a certain number of zeros at z=-1 for a symmetric filter and make it satisfy the power complementary condition as accurately as possible. From this filter, a semi-orthogonal wavelet filter bank which is nearly orthogonal can be constructed. This semi-orthogonal filter bank can be approximately implemented using a filter bank consisting of only one prototype filter. The frequency selectivity can also be designed at the same time by using a weighted cost function     

Mg2NiH: A new hydride phase in the Mg2Ni---H2 system

A new hydride phase apart from Mg₂NiH₄ has been identified in the Mg₂Ni---H₂ system by pressure-composition-temperature relationships, thermal analyses and X-ray diffraction measurements. The new phase has an approximate composition Mg₂NiH and is considered to be the intermediate phase in the Mg₂Ni---H₂ reaction. The additional hydride phase, Mg₂NiH (named as β-hydride) and the full hydride phase, Mg₂NiH₄ (named as γ-hydride) have been shown to crystallize in monoclinic structure. The β-phase (Mg₂NiH) also exhibits a phase transition from monoclinic to cubic structure similar to the γ-phase (Mg₂NiH₄).     

Bioleaching of lateritic nickel ore by ultrasound

The bioleaching of nickel from lateritic ore of Orissa, India, using a nativeAspergillus niger strain was studied with and without ultrasound. Different parameters, such as spore concentration, amount of dextrose in the medium, pulp densities, and sonication time, were studied for maximizing the extraction of nickel. Enhanced recoveries and reduction in leaching time were demonstrated using ultrasound. The highest amount of nickel, 95 pct, was extracted in 14 days with an inoculum size of 10⁶ spore/mL and 2 pct dextrose in the medium under 30 minutes ultrasonic pretreatment using 43 KHz frequency at 1.5 W/cm² intensity. It was also found that ultrasound assists in selective leaching of nickel over iron.     

Glycation mediated lens crystallin aggregation and cross-linking by various sugars and sugar phosphates in vitro

BACKGROUND: The role of coronary spasm in underlying disease-free patients who were resuscitated from sudden cardiac arrest remained uncertain. This study investigated the cause of cardiac arrest, and the etiologic and prognostic differences were compared between patients with underlying heart disease (group I) and those patients without underlying heart disease (group II). METHODS: Twenty-five survivors of sudden cardiac arrest were classified into two groups according to the presence or absence of underlying heart disease. To investigate the cause of cardiac arrest, we performed ergonovine testing and electrophysiologic study. Fifteen of the patients had underlying heart disease, while 10 did not. RESULTS: Electrophysiologic abnormalities were found in 13 of the 15 patients in group I. In group II, spontaneous attack of coronary spasm occurred in four patients during the observation period, and coronary spasm was induced in three of the remaining six period of 32 +/- 23 months, whereas no patients in group II had recurrence of sudden cardiac arrest at a median follow-up of 32 months (range, 10 to 72 months). CONCLUSIONS: Electrophysiologic study identified a potential cause in 13 of 15 patients with underlying heart disease. Coronary spasm was involved in the pathogenesis of sudden cardiac arrest in survivors without identifiable underlying heart disease.     

Constrained notch filtering of nonuniformly spaced samples forenhancement of an arbitrary signal corrupted by a strong FM interference

The proposed method is based on exploring the concept of constrained notch filtering (CNF) as applied to any given arbitrary signal with time varying parameters. First, it is shown that any signal with a constant envelope such as FM may be transformed to a discrete sinusoidal one by applying a nonuniform sampling strategy. Second, a signal buried under a strong FM interference is retrieved by applying CNF in the transformed time domain. The main assumption made is that there exists an auxiliary input which provides information about the instantaneous frequency of the interference     

Ultimate punching shear strength analysis of slab–column connections

A simple analytical model is presented to predict the ultimate punching shear strength of slab–column connections. The model is based on the physical behavior of the connections under load, and is therefore applicable to both lightweight and normal weight concrete. The model assumes that punching is a form of combined shearing and splitting, occurring without concrete crushing, but under complex three dimensional stresses. Failure is then assumed to occur when the tensile splitting strength of the concrete is exceeded. The theory is applied to predict the ultimate punching shear strength of 60 slab–column connections reported recently in literature, and designed to fail in shear, involving a large number of variables, such as type of concrete, concrete strength, tension steel ratio, compression reinforcement and loaded area. The results show very good agreement between the predicted and experimental values. The uniqueness of the model is that it incorporates many physical characteristics of the slabs and their failure behavior, and this is reflected by its ability to predict extremely well the results of tests conducted by researchers other than the authors.     

Internet-based educational control systems lab using NetMeeting

The purpose of the paper is to illustrate the remote control of hardware in the laboratory for educational purposes, using commercial off-the-shelf equipment and available freeware. The goal is to eliminate extensive programming using high-level languages, such as Java programming to achieve remote connectivity and focus on the primary task of implementing control algorithms. The use of MS NetMeeting for Internet-based control is described. Control experiments were easily carried out by a remote user, using Matlab-based real-time tools and MS NetMeeting