56 research outputs found
Heat capacity of a thin membrane at very low temperature
We calculate the dependence of heat capacity of a free standing thin membrane
on its thickness and temperature. A remarkable fact is that for a given
temperature there exists a minimum in the dependence of the heat capacity on
the thickness. The ratio of the heat capacity to its minimal value for a given
temperature is a universal function of the ratio of the thickness to its value
corresponding to the minimum. The minimal value of the heat capacitance for
given temperature is proportional to the temperature squared. Our analysis can
be used, in particular, for optimizing support membranes for microbolometers
Comparative analysis of the structure and internal stress in Ti-6Al-4V alloys manufactured by 3D printing and processing with screw extrusion
Study is based on the compare characterization of the structure and evaluation of the residual internal stresses in Ti-6Al-4V samples manufactured by the 3D printing (selective laser melting) and in the Ti-6Al-4V samples obtained with using of the severe plastic deformation by screw extrusion. The microstructure and residual stresses were examined by transmission electron microscope and X-ray diffractometer. High tensile internal residual stresses in the 3D printed sample were found. The high compressive residual internal stresses were found in the hot pressed and in the twisted samples. It was shown that arising of the high residual stresses in the studied samples under various technological processes occurred in various ways. The residual stresses in the severe plastic deformed samples arose due to non-uniform volumetric plastic deformation. In 3D printed sample, the residual tensile stresses arose from both phase (martensitic) transformation and thermal deformation. Β© Published under licence by IOP Publishing Ltd
Microstructure and mechanical properties of Al-12Si produced by selective laser melting
Al-12Si specimens are produced by selective laser melting (SLM) from gas atomized powders. Installation for the production of powder is original. All specimens were prepared using the EOSINT M 280 device. A fine cellular structure is observed with residual free Si along the cellular boundaries. Room temperature tensile tests reveal remarkable mechanical behavior: the samples show yield and tensile strengths of about 102 MPa and 425 MPa, respectively, along with fracture strain of 12%. The study of crack surface morphology was shown by the example of a sample. Except the spherical pores, the interface of the molten pool also appears on the fracture surface, which indicates a mixture of fragile and ductile fracture. Additionally, the agglomerated silicon group appears also on the fracture surface. Β© Published under licence by IOP Publishing Ltd
Microstructure and mechanical properties of Al-12Si produced by selective laser melting
Al-12Si specimens are produced by selective laser melting (SLM) from gas atomized powders. Installation for the production of powder is original. All specimens were prepared using the EOSINT M 280 device. A fine cellular structure is observed with residual free Si along the cellular boundaries. Room temperature tensile tests reveal remarkable mechanical behavior: the samples show yield and tensile strengths of about 102 MPa and 425 MPa, respectively, along with fracture strain of 12%. The study of crack surface morphology was shown by the example of a sample. Except the spherical pores, the interface of the molten pool also appears on the fracture surface, which indicates a mixture of fragile and ductile fracture. Additionally, the agglomerated silicon group appears also on the fracture surface. Β© Published under licence by IOP Publishing Ltd
Oxygen and nitrogen concentrations in the Ti-6Al-4V alloy manufactured by direct metal laser sintering (DMLS) process
Published ArticleTwo machines from two scientific centers (Russia and South Africa) were used for the manufacturing of
the Ti6Al4V alloys by the direct metal laser sintering. The chemical composition of powders complies
with the ASTM F-136 (grade 5), ASTM B348 (grade 23) standard for medical applications. Analysis of
the oxygen and nitrogen contamination in DMLS alloys was done with Van de Graaff accelerator with
two Mega Volts. It is found that structures of the samples manufactured with two different machines
used the same regimes are close to each other. TEM studies found the metastable martensitic structure
and silicon nitride Si3N4. It was found that the oxygen and nitrogen contents in both samples are within
the normal range for medical grade titanium alloys
Functional activity of the oral endothelium in persons, with chronic periodontitis during treatment with plasmolifting
Chronic periodontitis as an osteoimmune disease of the oral cavity is accompanied by a change in the functional activity of endotheliocytes. Moreover, abnormal vascularization exacerbates periodontal inflammation, as it promotes the transmigration of a larger number of immunocompetent cells, the influx of inflammatory mediators and cytokines.The aim of our work was to study the functional activity of the endothelium of the vessels of the oral cavity in persons suffering from chronic periodontitis in the treatment of plasmolifting.Materials and methods. Under observation were 30 patients diagnosed with chronic generalized periodontitis of moderate severity at the age of 35 (32.50; 40.00) years, with no severe somatic pathology (main group). The comparison group included 20 people aged 38 (34.00; 45.00) years with no inflammatory diseases in the oral cavity. All patients underwent local anti-inflammatory therapy and sanitation of periodontal pockets, correction of occlusal contacts, curettage, plasma lifting. Oral fluid concentration of soluble adhesion molecules ICAM-1 and VCAM-1, endothelin-1, qualitative and quantitative composition of microflora were determined.Results. After the treatment with plasmolifting, a noticeable relief of the activity of the inflammatory process was observed. In patients with chronic periodontitis, Porphyromonas gingivalis was found in 100 % of cases in a titer of 5.73 (4.9; 6.7) lg (gEq/sample), in 62.5 % β Prevotella intermedia in a titer of 4.5 (3.0; 5.5) lg (gEq/sample). Against the background of therapy, decrease of the occurrence of the microorganism and of the number of microorganisms was observed. The concentration of the soluble form of VCAM-1 in the oral fluid of patients with chronic periodontitis exceeded the values of the control group by 38.3 times (p = 0.000001), and ICAM-1 β by 18.1 times (p = 0.00001). Against the background of plasmolifting therapy, the level of the studied substances decreased, but exceeded the control values by 25.2 and 6.4 times, respectively. The content of endothelin in the oral fluid in patients with periodontitis exceeded the values of healthy individuals by 40.7 % (p = 0.003), during therapy its values decreased, but did not reach the level of healthy volunteers (p = 0.04)
Goltsov phenomenon as a natural-technogenic electromagnetic discharge of the lithosphere
The article presents data on an unusual natural phenomenon that occurred on November 30, 1984 in the village of Goltsovka, Zmeinogorsky District, Altai Territory. It manifested itself in the passage above the village of a luminous ball, which was accompanied by an impact on the surface of the earth and led to some damage to structures and buildings. A detailed description of this unusual phenomenon in the published scientific literature, as far as we know, is practically absent. The article describes this phenomenon, based on data collected soon after the event, with the addition of upto-date clarifying information. A comparison is made with several known cases of ball lightning and a whirlwind. The conclusion is made about an unusually large energy release in the Goltsovka event
ΠΠΎΡΡΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ ΡΠ°Π·Π½ΠΎΠΊΠ°ΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎΡΡΠΈ ΡΠ΅ΠΌΡΠ½ ΠΌΠΎΡΠΊΠΎΠ²ΠΈ ΠΈ ΡΠ°ΠΊΡΠΎΡΡ ΠΈΡ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡΠΈΠ΅.
Relevance.The contribution of varietal and environmental factors to the variability of the length of the endosperm and the embryo of carrot seeds was studied. Materials and methods. The objects of study were the original seeds of Rogneda, Lubava and Chernozemochka, Chantene 2461 and Boyarynya varieties. The seeds were grown at the Voronezh and West Siberian experimental stations. The linear dimensions of the seed and endosperm were measured using a caliper. The length of the embryo was measured using a microscope (Micromed) and a video eyepiece (DCM 300 MD) at Ρ
40 magnification. Statistical processing of the research data two-factor experiment was carried out using analysis of variance. Differences in the compared parameters were considered statistically significant at p 0.05.Results. The linear dimensions of all the main elements of seeds, as well as the index of Ie/z on average for three years significantly differed in the studied carrot varieties (P < 0.001). The maximum length of the seed (3.14Β±0.02 mm), the length of the endosperm (2.66Β±0.02 mm) and the length of the embryo (1.23Β±0.03 mm) on average for three years was observed in the Rogneda variety. The average coefficient of variation (V) of seed length was minimal and varied from 10.1% to 12.9%. The average values of the coefficient of variation (V) for the length of the endosperm varied in a wider range from 12.0% to 14.6%. The length of the embryo had a maximum level of variability from 18.7% in the Rogneda variety to 20.3% in the Chernozemochka variety 21.3%. The variety factor had a predominant influence (from 50.8 % to 86.5 %) on the size of the seed and its morphological elements. The contribution of the environmental conditions of the year of reproduction to the formation of morphometric parameters did not exceed 22.3 %. This allowed us to draw a conclusion about the prospects of selection and the possibility of selective changes in the morphological parameters of the seed.Β ΠΠΊΡΡΠ°Π»ΡΠ½ΠΎΡΡΡ. ΠΠ·ΡΡΠ΅Π½ Π²ΠΊΠ»Π°Π΄ ΡΠΎΡΡΠΎΠ²ΠΎΠ³ΠΎ ΠΈ ΡΠΊΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ°ΠΊΡΠΎΡΠΎΠ² Π² ΠΈΠ·ΠΌΠ΅Π½ΡΠΈΠ²ΠΎΡΡΡ Π΄Π»ΠΈΠ½Ρ ΡΠ½Π΄ΠΎΡΠΏΠ΅ΡΠΌΠ° ΠΈ Π·Π°ΡΠΎΠ΄ΡΡΠ° ΡΠ΅ΠΌΡΠ½ ΠΌΠΎΡΠΊΠΎΠ²ΠΈ.Β ΠΠ°ΡΠ΅ΡΠΈΠ°Π» ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ. ΠΠ±ΡΠ΅ΠΊΡΠ°ΠΌΠΈ Π΄Π»Ρ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΡΠ»ΡΠΆΠΈΠ»ΠΈ ΠΎΡΠΈΠ³ΠΈΠ½Π°Π»ΡΠ½ΡΠ΅ ΡΠ΅ΠΌΠ΅Π½Π° ΡΠΎΡΡΠΎΠ² Π ΠΎΠ³Π½Π΅Π΄Π°, ΠΡΠ±Π°Π²Π° ΠΈ Π§Π΅ΡΠ½ΠΎΠ·Π΅ΠΌΠΎΡΠΊΠ°, Π¨Π°Π½ΡΠ΅Π½Ρ 2461 ΠΈ ΠΠΎΡΡΡΠ½Ρ. Π‘Π΅ΠΌΠ΅Π½Π° Π²ΡΡΠ°ΡΠ΅Π½Ρ Π½Π° ΠΠΎΡΠΎΠ½Π΅ΠΆΡΠΊΠΎΠΉ ΠΈ ΠΠ°ΠΏΠ°Π΄Π½ΠΎ-Π‘ΠΈΠ±ΠΈΡΡΠΊΠΎΠΉ ΠΎΠΏΡΡΠ½ΡΡ
ΡΡΠ°Π½ΡΠΈΡΡ
. ΠΠ·ΠΌΠ΅ΡΠ΅Π½ΠΈΠ΅ Π»ΠΈΠ½Π΅ΠΉΠ½ΡΡ
ΡΠ°Π·ΠΌΠ΅ΡΠΎΠ² ΡΠ΅ΠΌΠ΅Π½ΠΈ ΠΈ ΡΠ½Π΄ΠΎΡΠΏΠ΅ΡΠΌΠ° ΠΎΡΡΡΠ΅ΡΡΠ²Π»ΡΠ»ΠΈ ΡΡΠ°Π½Π³Π΅Π½ΡΠΈΡΠΊΡΠ»Π΅ΠΌ. ΠΠ»ΠΈΠ½Ρ Π·Π°ΡΠΎΠ΄ΡΡΠ° ΠΈΠ·ΠΌΠ΅ΡΡΠ»ΠΈ Ρ ΠΏΠΎΠΌΠΎΡΡΡ ΠΌΠΈΠΊΡΠΎΡΠΊΠΎΠΏΠ° (ΠΠΈΠΊΡΠΎΠΌΠ΅Π΄) ΠΈ Π²ΠΈΠ΄Π΅ΠΎΠΎΠΊΡΠ»ΡΡΠ° (DCM 300 MD) ΠΏΡΠΈ x40 ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΠΈ. Π‘ΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΡΡ ΠΎΠ±ΡΠ°Π±ΠΎΡΠΊΡ Π΄Π°Π½Π½ΡΡ
ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ Π΄Π²ΡΡ
ΡΠ°ΠΊΡΠΎΡΠ½ΠΎΠ³ΠΎ ΠΎΠΏΡΡΠ° ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΈ Ρ ΠΏΠΎΠΌΠΎΡΡΡ Π΄ΠΈΡΠΏΠ΅ΡΡΠΈΠΎΠ½Π½ΠΎΠ³ΠΎ Π°Π½Π°Π»ΠΈΠ·Π°. Π Π°Π·Π»ΠΈΡΠΈΡ ΡΡΠ°Π²Π½ΠΈΠ²Π°Π΅ΠΌΡΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΡΡΠΈΡΠ°Π»ΠΈ ΡΡΠ°ΡΠΈΡΡΠΈΡΠ΅ΡΠΊΠΈ Π·Π½Π°ΡΠΈΠΌΡΠΌΠΈ ΠΏΡΠΈ Π 0,05.Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. ΠΠΈΠ½Π΅ΠΉΠ½ΡΠ΅ ΡΠ°Π·ΠΌΠ΅ΡΡ Π²ΡΠ΅Ρ
ΠΎΡΠ½ΠΎΠ²Π½ΡΡ
ΡΠ»Π΅ΠΌΠ΅Π½ΡΠΎΠ² ΡΠ΅ΠΌΡΠ½, Π° ΡΠ°ΠΊΠΆΠ΅ ΠΈΠ½Π΄Π΅ΠΊΡ IΡ/Π· Π² ΡΡΠ΅Π΄Π½Π΅ΠΌ Π·Π° ΡΡΠΈ Π³ΠΎΠ΄Π° ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎ ΠΎΡΠ»ΠΈΡΠ°Π»ΠΈΡΡ Ρ ΠΈΠ·ΡΡΠ΅Π½Π½ΡΡ
ΡΠΎΡΡΠΎΠ² ΠΌΠΎΡΠΊΠΎΠ²ΠΈ (Π < 0,001). ΠΠ°ΠΊΡΠΈΠΌΠ°Π»ΡΠ½Π°Ρ Π΄Π»ΠΈΠ½Π° ΡΠ΅ΠΌΠ΅Π½ΠΈ (3,14Β±0,02 ΠΌΠΌ), Π΄Π»ΠΈΠ½Π° ΡΠ½Π΄ΠΎΡΠΏΠ΅ΡΠΌΠ° (2,66Β±0,02 ΠΌΠΌ) ΠΈ Π΄Π»ΠΈΠ½Π° Π·Π°ΡΠΎΠ΄ΡΡΠ° (1,23Β±0,03 ΠΌΠΌ) Π² ΡΡΠ΅Π΄Π½Π΅ΠΌ Π·Π° ΡΡΠΈ Π³ΠΎΠ΄Π° ΠΎΡΠΌΠ΅ΡΠ΅Π½Π° Ρ ΡΠΎΡΡΠ° Π ΠΎΠ³Π½Π΅Π΄Π°. Π‘ΡΠ΅Π΄Π½ΠΈΠ΅ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° Π²Π°ΡΠΈΠ°ΡΠΈΠΈ (V) Π΄Π»ΠΈΠ½Ρ ΡΠ΅ΠΌΠ΅Π½ΠΈ Π±ΡΠ»ΠΈ ΠΌΠΈΠ½ΠΈΠΌΠ°Π»ΡΠ½ΡΠΌΠΈ ΠΈ ΠΈΠ·ΠΌΠ΅Π½ΡΠ»ΠΈΡΡ ΠΎΡ 10,1% Π΄ΠΎ 12,9%. Π‘ΡΠ΅Π΄Π½ΠΈΠ΅ Π·Π½Π°ΡΠ΅Π½ΠΈΡ ΠΊΠΎΡΡΡΠΈΡΠΈΠ΅Π½ΡΠ° Π²Π°ΡΠΈΠ°ΡΠΈΠΈ (V) Π΄Π»Ρ Π΄Π»ΠΈΠ½Ρ ΡΠ½Π΄ΠΎΡΠΏΠ΅ΡΠΌΠ° ΠΈΠ·ΠΌΠ΅Π½ΡΠ»ΠΈΡΡ Π² Π±ΠΎΠ»Π΅Π΅ ΡΠΈΡΠΎΠΊΠΈΡ
ΠΏΡΠ΅Π΄Π΅Π»Π°Ρ
ΠΎΡ 12,0% Π΄ΠΎ 14,6%. ΠΠ»ΠΈΠ½Π° Π·Π°ΡΠΎΠ΄ΡΡΠ° ΠΈΠΌΠ΅Π»Π° ΠΌΠ°ΠΊΡΠΈΠΌΠ°Π»ΡΠ½ΡΠΉ ΡΡΠΎΠ²Π΅Π½Ρ Π²Π°ΡΠΈΠ°Π±Π΅Π»ΡΠ½ΠΎΡΡΠΈ ΠΎΡ 18,7% Ρ ΡΠΎΡΡΠ° Π ΠΎΠ³Π½Π΅Π΄Π° Π΄ΠΎ 20,3% Ρ ΡΠΎΡΡΠ° Π§Π΅ΡΠ½ΠΎΠ·Π΅ΠΌΠΎΡΠΊΠ° 21,3%. Π€Π°ΠΊΡΠΎΡ ΡΠΎΡΡΠ° ΠΎΠΊΠ°Π·ΡΠ²Π°Π» ΠΏΡΠ΅ΠΎΠ±Π»Π°Π΄Π°ΡΡΠ΅Π΅ Π²Π»ΠΈΡΠ½ΠΈΠ΅ (ΠΎΡ 50,8% Π΄ΠΎ 86,5%) Π½Π° ΡΠ°Π·ΠΌΠ΅Ρ ΡΠ΅ΠΌΠ΅Π½ΠΈ ΠΈ Π΅Π³ΠΎ ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΡΠ»Π΅ΠΌΠ΅Π½ΡΡ. ΠΠΊΠ»Π°Π΄ ΡΠ°ΠΊΡΠΎΡΠ° ΡΠΊΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΡΠ»ΠΎΠ²ΠΈΠΉ Π³ΠΎΠ΄Π° ΡΠ΅ΠΏΡΠΎΠ΄ΡΠΊΡΠΈΠΈ Π² ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΌΠΎΡΡΠΎΠΌΠ΅ΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² Π½Π΅ ΠΏΡΠ΅Π²ΡΡΠ°Π» 22,3%. ΠΡΠΎ ΠΏΠΎΠ·Π²ΠΎΠ»ΠΈΠ»ΠΎ ΡΠ΄Π΅Π»Π°ΡΡ Π²ΡΠ²ΠΎΠ΄ ΠΎ ΠΏΠ΅ΡΡΠΏΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ ΠΎΡΠ±ΠΎΡΠ° ΠΈ Π²ΠΎΠ·ΠΌΠΎΠΆΠ½ΠΎΡΡΠΈ ΡΠ΅Π»Π΅ΠΊΡΠΈΠΎΠ½Π½ΠΎΠ³ΠΎ ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ ΠΌΠΎΡΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΡ
ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΠΎΠ² ΡΠ΅ΠΌΠ΅Π½ΠΈ, ΠΊΠΎΡΠΎΡΡΠ΅ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΡΡ ΡΠ΅Ρ
Π½ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠ΅, ΠΏΠΎΡΠ΅Π²Π½ΡΠ΅ ΠΈ Π΄ΡΡΠ³ΠΈΠ΅ ΠΈΡ
ΡΠ²ΠΎΠΉΡΡΠ²Π°.
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