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—A method of determining the packing density of coal concentrates in open storage is proposed and tested at AO Ural Steel. The variation in packing density over the height and length of the coal stack is determined. A protocol is developed for determining the packing density of coal concentrates in open storage.

—The properties of tar from the high-temperature coking of volatile-rich petroleum coke (CA, coking additive) are compared with the properties of coal tar. According to thermogravimetric data for the residue at temperatures beyond 360°C, the content of high-boiling components is considerably higher for petroleum tar than for coal tar. However, its yield of coke residue is lower than for coal tar. The petroleum tar contains polyaromatic hydrocarbons and heterocyclic sulfur-containing compounds, both of which are also found in coal tar. However, much larger quantities of sulfur-containing quantities are seen in petroleum tar, while the content of individual polyaromatic hydrocarbons is much lower.

Laboratory coking of experimental batch simulating the industrial batch at OAO Altai-Koks provides the basis for a model predicting the quality (CSR, CRI) of laboratory coke on the basis of the coking indices $$C{{I}^{{{{V}_{{\text{o}}}}}}}$$ and CI. The relation derived between the quality (CSR, CRI) of the laboratory coke and the quality (CSR, CRI) of industrial coke produced by wet and dry quenching permits prediction of CSR,CRI for the industrial coke on the basis of predicted or experimental CSR and CRI values for the laboratory coke. This approach permits ongoing determination of the CSR and CRI values of industrial coke produced with wet and dry quenching in the following circumstances: (i) in correcting production batch on the basis of the coal components available in the store and other nearby coal resources; (ii) in correcting production batch by means of outside concentrates not currently available at the plant; (iii)in analysis of the reasons for quality changes of the coke at any moment; (iv) in developing promising batches as the market for coking coal changes.

The properties of coking batch may be stabilized by means of DK coking additive based on the products of petroleum pyrolysis, characterized by low ash content (Ad = 0.4%), high sulfur content (Std= 4.1%), and high yield of volatiles (Vdaf = 17.2%) relative to coal concentrates. Individual coking of DK coking additive yields a product (particle size >40 mm) with postreactive strength CSR = 77–79%, reactivity CRI = 18–22%, and density 1200–1400 kg/m3. Differential scanning calorimetry of experimental coke samples reveals six stages in their heat treatment in air: preliminary heating, intense oxidation, gasification of carbon, surface combustion of the gaseous products, their flare combustion, and oxidation of the residue. The use of DK coking additive in the coking batch shifts the oxidation process to higher temperatures and ensures the largest interval of heat liberation at elevated heating rate, with up to 50% DK additive. With increase in the content of DK additive from 30 to 50%, the activation energy is increased by 4.56 kJ/mol for each additional 10%. In that case, the supply of atmospheric oxygen to the combustion zone must be improved

The introduction of DK coking additive to the coal batch improves the metallurgical properties of the coke produced. The quality of coke produced exclusively from DK additive permits its effective use. When introduced in the axial zone of the charge hole, it forms an axial ventilation region and thus the hearth may be packed with coke that is not susceptible to wetting by slag melt.

Analysis of the chemical composition of solid fuel permits the identification of the optimal proportions of its components for effective heat generation. Kinetic analysis of the oxidation of the carbon in the coke, by means of the complete curve obtained in differential scanning calorimetry with continuous heating, reveals six basic periods: drying and heating; oxidation of the carbon in the coke; endothermal gasification; surface oxidation of the gaseous products; flame combustion of the gaseous products, and oxidation of interior layers of the fuel. By assessing the behavior of the coke in shaft furnaces, the requirements on its granulometric composition, density, and mechanical strength in transportation and heat treatment may be determined. Recommendations are made regarding the characteristics of coke for use in the basic forms of cupola furnaces.

The influence of DK coking additive from oil refining—specifically, the solid product from the slow coking of heavy petroleum residues—in coal batch on the quality of the coke produced is studied in laboratory conditions. In comparison with coal concentrates, DK coking additive is characterized by lower ash content (Ad = 1.1%) and higher sulfur content (Std= 3.7%); the yield of volatiles Vdaf = 18.2%. The DK coking additive is added to the batch in doses of 4.8%, 9.1%, and 13%, with proportional decrease in the batch components. In other cases, DK coking additive is added to the batch in doses of 10%, in place of coal of the clinkering and coke groups. Coke is produced from the batch in the laboratory. The coal charge is 2 kg; the piece size is ≤3 mm. With increase in the content of DK coking additive to 13%, the strength of the coke after reaction (CSR) increases linearly from 49.2 to 54.9%, while the reactivity CRI declines linearly from 37.9 to 33.8%. The improvement in coke quality is greatest when GZh coal (a clinkering component) is replaced by the DK additive: CSR rises to 59.2% and CRI falls to 30.8%. The most promising approach is to replace the scarcest and most expensive coal—OS coal (the coke group) and KS coal (the lean group)—with DK additive, with 3.8% increase in CSR and 3.3% decrease in CRI.

Degree of hernia size influence on final result of PL M E in 34 patients with discogenic ne u rocompressive lumbar spin al syndrome was detected. I n medical center "Endoscopic Neurosurgery" from 2006 to 2010 w e examined and treated 34 patients with hernia size from 6 to 8 mm by CT data . Patients were from 19 to 49 years of age. Average age was 35.9 ± 1.5 years. Males – 16 (47.1%), females – 18 (52.9%). Disease duration – 5.53 ± 0.44 months with duration of last exacerbation – 1.87 ± 0.21 months. Duration of conservative therapy is 4.6 ± 2.1 weeks. During survey and objec ­ tive examination we determined pain syndrome intensity, pain location, degree of spin al static – dynamic function disorder. Neurological examination determined severity of sensory and motor disorders. Pain syndrome intensity, quality of life in patients before and after surgery, surgery effectiveness were determined by common scales: VAS, OSWESTRY, Roland - Morris, McNab. Before PLM E we evaluated preoperative spondylograms performed with functional load. Height of intervertebral fissure was determined by these images. B y SCT and MRI data w e measured hernia size, its shape and location as well as intervertebral disk dehydration degree. For PLM E performance we used neodymium laser with aluminum garnet (Dorinyer Fibertom Medilas 4060) with wave - length of 1.06 micrometers. In the next period of observation after PLM E its effectiveness was 79%, and in 3 - 5 years - 76%. At the same time it must be emphasized that 75% of patients with discogenic ne u rocompressive lumbar spin al syndrome significantly and for a long time improved their life quality avoiding more traumatic surgery. Satisfactory results with PLM use in the nearest future could be obtained in 79% of patients , in the remote term - in 76% of patients with large hernia size .

Pyrolysis of polyacrylonitrile mixtures with coal-tar pitch, pitch from heavy tar in ethylene production, and poly(vinyl chloride), a precursor of poly(vinyl chloride) pitch, was subjected to a comparative analysis. The content of various forms of nitrogen in the carbon materials obtained was determined.

The switching time and the optical control power of the NbN superconducting switch have been measured. The device is based on the ultrathin film 5-8 nm thick patterned as a structure of several narrow parallel strips (/spl sim/1 /spl mu/m wide) connected to wide current leads. The current-voltage characteristic of the switch at temperature 4.2 K demonstrated a hysteresis due to DC current self-heating. We studied the superconducting-to-resistive state transition induced by both optical and bias-current excitations. The optical pulse duration was /spl sim/20 ps and the rise time of the current step was determined to be less than 50 ps. The optical pulse was delivered to the switch by the semiconductor laser through an optical fiber. We found that the measured switching time is less than the duration of the optical excitation. The threshold optical power density does not exceed 3/spl middot/10/sup 3/ W/cm/sup 2/. The proposed device can be used in the fiber input of LTS rapid single flux quantum circuits.

Transitions of thin structured YBaCuO films from superconducting (S) to normal (N) state and back induced by a supercritical current pulse has been studied. A subnanosecond stage in the film resistance dynamic has been observed. A more gradual (nanosecond) ramp in the time dependence of the resistance follows the fast stage. The fraction of the film resistance which is attained during the fast S-N stage rises with the current amplitude. Subnanosecond N-S switching is more pronounced for smaller amplitudes of driving current and for shorter pulses. The phenomena observed are viewed within the framework of an electron heating model. The expected switching time and repetition rate of an optimized current controlling device are estimated to be 1-2 ps and 80 GHz respectively. >

High quality, j/sub c/ (77 K)>10/sup 6/ A/cm/sup 2/, epitaxial YBa/sub 2/Cu/sub 3/O/sub 7-x/ films of 50 nm thickness were patterned into ten parallel 1 /spl mu/m wide strips. The film structure was coupled to a single-mode fiber. Mixer response was obtained at 0.78 /spl mu/m using laser frequency modulation and an optical delay line. Using two semiconductor lasers at 1.55 /spl mu/m wavelength the beating signal was used to measure the photoresponse up to 18 GHz. Nonequilibrium photoresponse in the resistive state of the superconductor was observed. Bolometric response dominates up to 3 GHz, after which the nonequilibrium response is constant up to the frequency limit of our registration system. Using an electron heating model the influence of different thermal processes on the conversion loss has been analyzed. Ways of increasing the sensitivity are also discussed. >

A study is reported of the current switching in high‐quality YBaCuO films deposited onto NdGaO3 and ZrO2 substrates between superconducting (S) and normal (N) states. The films 60–120 nm thick prepared by laser ablation were structured into single strips between gold contacts. The time dependence of the resistance after application of the voltage step to the film was monitored. Experiment performed within certain ranges of voltage amplitudes and temperatures has shown the occurrence of the fast stage (shorter than 400 ps) both in S‐N and N‐S transitions. A fraction of the film resistance changing within this stage in the S‐N transition increases with the current amplitude. A subnanosecond N‐S stage becomes more pronounced for shorter pulses. The fast switching is followed by the much slower change of resistance. The mechanism of switching is discussed in terms of the hot‐electron phenomena in YBaCuO. The contributions of other thermal processes (e.g., a phonon escape from the film, a heat diffusion in the film and substrate, a resistive domain formation) in the subsequent stage of the resistance dynamic have been also discussed. The basic limiting characteristics (average dissipated power, energy needed for switching, maximum repetition rate) of a picosecond switch which is proposed to be developed are estimated.

Picosecond nonequilibrium and slow bolometric responses to infrared radiation from a patterned high-T c superconducting (HTS) film in resistive and normal states deposited onto LaAlO3, NdGaO3, and MgO substrates were investigated using both pulse and modulation techniques. The response time of 35 ps to a laser pulse of 17 ps FWHM has been observed. The intrinsic response time of the fast process is expected to be about a few picoseconds. The modulation technique, being free from the disadvantages of pulse methods (poor sensitivity, limited dynamic range), makes the detailed study of a number of relaxation processes possible. Besides the nonequilibrium response, two kinds of bolometric processes, namely phonon transport through the film-substrate interface and phonon thermal diffusion in a substrate, manifest themselves in certain frequency dependences.

Epitaxial laser deposited YBa2Cu3O7−δ films of ∼50 nm thickness were patterned into detectors consisting of ten parallel 1 μm wide strips in order to study nonequilibrium and bolometric effects. Typically, the patterned samples had critical temperatures around 86 K, transition widths around 2 K and critical current densities above 1×106A/cm2 at 77 K. Pulsed laser measurements at 0.8 μm wavelength (17 ps full width at half maximum) showed a ∼30 ps response, attributed to electron heating, followed by a slower bolometric decay. Amplitude modulation in the band fmod=100 kHz–10 GHz of a laser with wavelength λ=0.8 μm showed two different thermal relaxations in the photoresponse. Phonon escape from the film (∼3 ns) is the limiting process, followed by heat diffusion in the substrate. Similar relaxations were also seen for λ=10.6 μm. The photoresponse measurements were made with the film in the resistive state and extended into the normal state. These states were created by supercritical bias currents. Measurem...

The authors report on the application of a broad-band NbN film detector which has high sensitivity and picosecond response time for detection of radiation from millimetre wavelengths to visible light. From a study of amplitude modulated radiation of backward-wave tubes and picosecond pulses from gas and solid state lasers at wavelengths between 2 mm and 0.53 mu m, they found a detectivity of 1010 W-1 cm Hz-1/2 and a response time of less than 50 ps at T=10 K. The characteristics were provided by using a 150 AA thick NbN film patterned into a structure of micron strips. According to the proposed detection mechanism, namely electron heating, they expect an intrinsic response time of approximately 20 ps at the same temperature.

Sapropel was tested for its effect on the permeability of erythrocytic membranes and on the erythrocytic and serum levels of ceruloplasmin, malonic dialdehyde, and dienic conjugates in rats after acute poisoning by carbofos, a malathion insecticide. The increased processes of free radical oxidation during carbofos poisoning were suggested by the higher rates of chemiluminescence of erythrocytes and peripheral blood serum. No significant changes in the parameters of blood oxidative stress in the carbofos-poisoned animals during therapeutic-and-prophylactic use of sapropel indicate that the latter has antioxidative properties. Application of sapropel to normal animals exerted no effect of the studied parameters of oxidative stress. In acute carbofos poisoining, oral sapropel produced a pronounced antioxidative effect, which opens up new vistas for its practical application.

Hot‐electron bolometric (HEB) mixing of 9.6 μm infrared radiation from two lasers in high‐quality YBa2Cu3O7−δ (YBCO) patterned thin film has been demonstrated. A heterodyne measurement showed an intermediate frequency (IF) bandwidth of 18 GHz, limited by our measurement system. An intrinsic limit of 100 GHz is predicted. Between 0.1 and 1 GHz intermediate frequency, temperature fluctuations with an equivalent output noise temperature Tfl up to ∼150 K, contributed to the mixer noise while Johnson noise dominated above 1 GHz. The overall conversion loss at 77 K at low intermediate frequencies was measured to be ∼25 dB, of which 13 dB was due to the coupling loss. The HEB mixer is very promising for use in heterodyne receivers within the whole infrared range.

Mixing of 1.56 μm infrared radiation from two lasers in a high quality YBa2Cu3O7−δ thin film, patterned to parallel strips, was demonstrated. A mixer bandwidth of 18 GHz, limited by the measurement system, was obtained. A model based on nonequilibrium electron heating gives a good fit to the data and predicts an intrinsic mixer bandwidth in excess of 100 GHz, operating in the whole infrared spectrum. Reduction of bolometric effects and ways to decrease the conversion loss of the mixer is discussed. The minimum conversion loss is expected to be ∼10 dB.

Thin YBa2Cu3O7−δ laser deposited films were patterned into devices consisting of ten parallel 1 μm wide strips. Nonequilibrium picosecond and bolometric photoresponses were studied by the use of 17 ps full width at half‐maximum laser pulses and amplitude modulated radiation from an AlGaAs laser up to 10 GHz and from a CO2 laser up to 1 GHz. The time and frequency domain measurements were in agreement. The fast response can be explained by electron heating. The use of low optical power and a sensitive measurement system excluded any nonlinear transient processes and kinetic inductance changes in the superconducting state. At 1 GHz modulation frequency, the responsivity was ∼1.2 V/W both for 0.8 and 10.6 μm wavelengths. The sensitivity of a fast and spectrally broadband infrared detector is discussed.

Detectors for infrared radiation ( lambda =0.85 mu m) were made of 50 nm thick YBa2Cu3O7- delta films on LaAlO3 and MgO or 60 nm thick films on NdGaO3. Parallel strips (1 mu m wide by 20 mu m long) were patterned in the films and formed the active device. These devices were designed to detect short infrared laser pulses by electron heating. The detectors were current biased into the resistive and the normal states. The response was studied in direct pulse measurements as well as by amplitude modulation of a laser. The pulse measurements showed a fast picosecond response followed by a slower decay related to phonon escape through the film-substrate interface and heat diffusion in the substrate. The frequency spectra up to 10 GHz showed two slopes with a knee corresponding to the phonon escape time.

We report on a study of S-N and N-S current switching in high quality YBaCuO films deposited onto ZrO2 and NdGaO3 substrates. The films 60-120 nm thick prepared by laser ablation were structured into single strips and were provided with gold contacts. We monitored the time dependence of the resistance upon application of the voltage step on the film. Experiment performed within certain ranges of voltage amplitudes and temperatures showed the occurrence of the fast stage both in S-N (shorter than 300 ps) and N-S transition. We discuss the mechanism of switching taking into account the hot electron phenomena in YBaCuO. The contributions of various thermal processes in the subsequent stage of the resistance dynamic are also discussed. The basic limiting characteristics (average dissipated power, minimum work done for switching, maximum repetition rate) of a picosecond switch which is proposed to be developed are estimated.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Nonequilibrium picosecond and bolometric responses of YBCO films 500 angstroms thick patterned into 20 X 20 micrometers 2 size structure to 17 ps laser pulses and modulated radiation of GaAs and CO 2 lasers have been studied. The modulation frequencies up to 10 GHz for GaAs laser and up to 1 GHz for CO 2 were attained. The use of small radiation power (1 - 10 mW/cm 2 for cw radiation and 10 - 100 nJ/cm 2 for pulse radiation) in combination with high sensitive read-out system made possible to avoid any non-linear transient processes caused by an overheating of sample above a critical temperature or S-N switching enhanced by an intense radiation. Responses due to the change of kinetic inductance were believed to be negligible. The only signals observed were caused by a small change of the film resistance either in the resistive state created by a bias current or in the normal state. The data obtained by means of pulse and modulation techniques are in agreement. The responsivity about 1 V/W was measured at 1 GHz modulation frequency both for 0.85 micrometers and 10.6 micrometers wavelengths. The sensitivity of high-T c fast wideband infrared detector is discussed.

The case records of 205 patients with brain ischemia of various degree severity accompanied by two and more main brain arteries occlusion are analyzed. In 176 operated patients 241 revascularizing intervention was conducted. The advantages of surgical method versus conservative one were established.

A transition of YBCO bridge 60 nm thick from superconducting to normal state induced by an abrupt current step has been studied. A subnanosecond stage has been observed during both S-N and N-S transition. The data obtained can be explained by hot-electron phenomena. On the basis of experimental results a prediction of picosecond switch performance has been made.