The process of electrochemical deposition of zinc in the presence of boron-doped detonation nanodiamonds

The influence of detonation of nanodiamonds doped with boron during the detonation synthesis (DND-boron) on the process of electrochemical deposition of zinc from a zincate electrolytic solution is investigated. It is shown that the throwing power (the coating uniformity) increases 2to 4-fold depending on the DND–boron concentration, the electrolytic conductivity remains unchanged, the corrosion resistance (as measured by the corrosion currents) of the Zn–DND-boron coating grows 2.6 times when tested in the 3% NaCl solution and 3 times in the climatic chamber.     

Comparison between TRH-stimulated TSH and basal TSH measurement by a commercial immunoradiometric assay in the management of thyroid disease

In order to assess the current diagnostic role of the TRH test following the introduction of more sensitive "second generation" TSH assays, we studied a series of 259 outpatients, 237 women and 22 men, mean age 44.7 years (range 12-82), 91 of whom (35%) with untreated simple goiter, 133 (51%) with simple nodular goiter on steady state I-thyroxine treatment, 18 (7%) with overt or subclinical hyperthyroidism and 17 (7%) with overt or subclinical hypothyroidism, compared to a control group of 26 euthyroid healthy subjects. Serum TSH was measured by a commercial immunoradiometric assay (clinical sensitivity 0.1 microU/ml). TSH response to TRH was evaluated 30 minutes after giving 200 micrograms TRH i.v. bolus, the results being analyzed both as absolute increase (delta-TSH=stimulated TSH minus basal TSH) and as relative increase (R-TSH stimulated TSH/basal TSH). Using cut-off values of 0.3-3.2 microU/ml, basal TSH measurement was able to detect hypothyroidism (specificity = 100%) and to exclude hyperthyroidism (sensivity = 96.9%), but failed to accurately prove hyperthyroidism (specificity = 93.4%) and, above all, to exclude hypothyroidism (sensitivity = 35.3%) in our ambulatory patients. The delta-TSH values showed a basal TSH dependent linear increase (r = + 0.87, p < 0.001) both including only patients (n = 139) with basal TSH level in the euthyroidism range and including all patients (n = 223) having TSH responsive to TRH. All the patients with detectable basal TSH level displayed detectable TSH response to TRH, as did 19 (= 23.5%) of 81 patients with undetectable (< 0.1 microU/ml) basal value. In particular: a) for subnormal but detectable basal TSH ranging between 0.1 and 0.2 microU/ml, TSH was always hyporesponsive (delta-TSH < or = 2.5 microU/ml), while between 0.2 and 0.3 microU/ml TSH was hyporesponsive in 72.2% and normoresponsive (delta-TSH > 2.5 and < or = 11.9 microU/ml) in the remaining 27.8%; b) for basal TSH values within the normal range (0.3-3.2 microU/ml). TSH was hyporesponsive in 13.7%, normoresponsive in 74.8% and hyperresponsive in 11.5%; c) for high basal TSH values TSH was always hyperresponsive. The analysis of R TSH showed relatively constant values in the range of euthyroidism and hypothyroidism (m +/- SD: 7.4 +/- 2.3 and 7.7 +/- 3.1, respectively), and a marked differentiation of hyperthyroid patients whose R-TSH values were significantly lower (4.2 +/- 3.4) but had a wide individual variability. Linear regression analysis of basal or stimulated TSH and circulating thyroid hormones showed a close negative relationship, being highly significant between delta-TSH and T4 (r = 0.57, p < 0.001) and delta-TSH and FT4 (r = 0.46, p < 0.001). In conclusion, after the introduction of current second generation TSH immunoradiometric assay, the diagnostic role of the TRH test is greatly limited but not to be excluded: it can provide additional information to that obtained with simple basal TSH measurement in the diagnosis of subclinical hypothyroidism and in the precise evaluation of the degree of TSH suppression in patients with a subnormal basal TSH, either for endogenous thyrotoxicosis or I.-thyroxine treatment.     

Leucaena (Leucaena leucocephala (Lam) de Wit) prunings as nitrogen source for maize (Zea mays L.)

The effectiveness ofLeucaena leucocephala (Lam.) de Wit, prunings as N source for maize (Zea mays L.) was evaluated in field and pot trials at Ibadan, southern Nigeria. An N deficient, sandy Apomu soil (Psammentic Usthorthent) was used. The prunings significantly increased N uptake of seedlings and N percentage in ear leaves of maize. High maize gain yield was obtained with application of 10 tons fresh prunings or a combination of 5 tons fresh prunings and N at 50 kg ha^–1. The prunings as N source, appeared to be more effective when incorporated in the soil than when applied as mulch. In the pot trial, prunings applied two weeks before planting was more effective than when applied at time of planting maize. Under screen house conditions, the apparent N recovery from prunings with early incorporation about equals that of fertilizer N.     

Use ofLeucaena leucocephala (Lam. de Wit) leaves as a nitrogen source for crop production

Field and pot trials were conducted to determine optimum management practices for usingLeucaena leucocephala (Lam. de Wit) leaves as a N source for crop production. Field trials with maize showed no benefit from split application of leucaena leaves or from application of fresh as opposed to dried material. Field trials also failed to show any difference between incorporation as opposed to surface application of leucaena leaves. This may be attributed to the low nitrogen response observed. Pot trials however, showed that soil incorporation of leucaena leaves was more effective than surface application in increasing plant dry weight.Leucaena leaves were not as effective as inorganic N in increasing maize grain yield (field trials) or dry matter production (pot trial). Unlike inorganic N, leucaena leaves had a significant residual effect on the succeeding maize crop. In decomposition studies, buried leucaena leaves decomposed more quickly than surface-applied leaves, and fresh leaves decomposed more rapidly than dried leaves.     

Technological aspects of heat treatment of hard alloys in the sintered state

Conditions and temperature and time parameters of quenching of hard alloy specimens and articles from tungsten group alloys have been studied. It is shown that the choice of quenching medium and temperature, holding time, and cooling rate is completely determined by the cobalt content in the alloy, the mass of the article to be quenched, and the presence of constructional stress concentrators. Quenching under optimal conditions increases the mechanical properties of the material, primarily its deformation characteristics under compression. This fact explains the longer service life of quenched components of high-pressure apparatuses, upsetting tools, dies, single-piece hard alloy drills, rock-breaking tools, etc.     

Asymptotic Stability Conditions and Estimates of Solutions for Nonlinear Multiconnected Time-Delay Systems

This paper examines certain classes of multiconnected (complex) systems with time-varying delay. Delay-independent stability conditions and estimates of the convergence rate of solutions to the origin for those systems are derived. It is shown that the exponents in the obtained estimates depend on the parameters of Lyapunov functions constructed for the corresponding isolated subsystems. The problem of computing parameter values that provide the most precise estimates is investigated. Some examples are presented to demonstrate the effectiveness of the proposed approaches.     

Influence of the size and charge of nonstoichiometric silver sulfide nanoparticles on their interaction with blood cells

Silver sulfide (Ag₂S) nanoparticles synthesized using different precursors have been characterized by dynamic light scattering measurements and high-resolution transmission electron microscopy. In addition to Ag₂S nanoparticles, we have detected Ag₂S/Ag heterostructures. Using optical microscopy, we have examined interaction of the nanoparticles with red cells of peripheral blood. The results of the interaction have been shown to depend on the particle size and charge. A red cell solution containing large, negatively charged particles coagulated, whereas small, positively charged Ag₂S nanoparticles were concentrated around red cells.     

Leaching of Radioactive Waste Surrogates from a Glassy Matrix and Migration of the Leaching Products in Gneisses

Changes in the glassy matrix containing high-level waste surrogates after 24-h heating in an autoclave at 300°С with steam at 66% relative humidity were studied. Experiments were performed with an Na–Al–P glass sample containing Cs, Sr, Ce, Nd, and U. The effect of crystallization on the leaching of the elements from the glassy matrix and the form in which the waste surrogates are released into water were determined. The transport of the leaching products in a gneiss sample taken from the core of a borehole of the Yeniseiskii site of the Nizhnekansky massif was studied. REE and U occur in the solution after leaching mainly in the colloidal form. Colloidal particles of elements exhibit high mobility in migration in the rock.     

An Investigation of the Possibility of Extraction of Metals from Heavy Oil

Experimental and theoretical studies of physical influence on the distribution of heavy metals and viscosity of heavy oils are given in the article. The oil of Yaregskoye (Timan-Pechora province) oil field was used as the test material. Microinclusions of metals (V, Ni, Ti, Fe, etc.) in the mineral parts were detected using scanning electron microscopy and electron microprobe analysis. In an attempt to extract these metals, effects of the extractant type, extractant concentration, and ultrasonic treatment on the extraction process were evaluated.     

Sensitization of the photoelectric effect in carbazole- and indolocarbazole-containing poly(phenylquinoline)s by benzothiadiazole acceptor molecules

The efficient sensitization of the photoelectric effect in mixed compositions of poly(phenylquinoline)s (PPQ) with 2,1,3-benzothiadiazole (BTDZ) molecules is established. The introduction of 10 wt % BTDZ results in extension of the spectral sensitivity range of PPQ and an increase in the photosensitivity and photocurrent by factors of 4.5 and more than 6, respectively. It is shown that the effect is caused by complex formation between PPQ donor fragments and BTDZ acceptor molecules; the strongest, in comparison with the increase in photosensitivity, is probably caused by the transport of free photogenerated carriers (electrons) over sensitizer molecules introduced into the polymer.