The paper presents methods for determining the elastic modulus, sound speed, logarithmic decrement of vibrations (internal friction), tensile, compressive and bending strength, crack resistance, ...specific work of fracture of small-sized specimens. The specimens of polycrystals of superhard materials, which are prepared in high-pressure apparatuses, or of other expensive sintered materials (boron carbide, silicon nitride, hard alloys), which have a high hardness and elastic modulus, have typically a small size. Most of such materials experience significant dynamic loads during operation in products (metal-cutting tools, armor protection elements). It has been shown that disk specimens of brittle materials 3–15 mm in size can be used to determine strength characteristics under dynamic loading. The use of such specimens makes it possible to avoid oscillations in the loading diagram and to reduce the measurement error of breaking load. Moreover, it is possible to determine on such specimens the specific work of fracture of brittle materials from energy balance in measuring bars. Methods for determining mechanical characteristics under dynamic loading using Hopkinson–Kolsky bars are described, and examples of using procedures for the investigation of hard alloys, polycrystals of superhard materials based on diamond and cubic boron nitride, boron carbide and silicon nitride, obtained by the Bakul Institute for Superhard Materials of the National Academy of Sciences of Ukraine, are given.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Established were the regularities of variations of the temperature, cutting tool force and roughness of the machined surface for different cutting rates at the precision turning of aluminium and ...brass alloys using a cutter with the diamond-hard alloy plate.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
—The dependence of the impact strength and damping characteristics of сBN–Al composite materials on the specific surface (grain size) of cubic boron nitride powders has been investigated. The ...correlation between the damping characteristics of the composite material and its phase composition has been established. The dependence of the phase composition of the material on the specific surface of the powdered cBN component has been demonstrated. Composite materials with a biphasic structure and the highest density and hardness possible for this structure had the maximal impact strength.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper addresses the variation of cutting temperatures and forces and machined surface roughness versus the cutting speed in fine turning of VT1-0 titanium alloy by a PCD tool. Optimal cutting ...conditions have been substantiated.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The process of cutting of an aluminum alloy has been monitored by the acoustic emission method. Single-crystal natural and synthetic diamond tools have been used in the investigation. The comparative ...analysis has demonstrated that the correlation model of acoustic emission, which was put forward by Pan and Dornfeld, is valid for the conditions of fine diamond turning of aluminum alloys.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The effect of phase composition of cutting inserts made of diamond–tungsten carbide nanocomposite on cutting forces, friction coefficient in the cutting zone, and acoustic emission signal in finish ...turning of aluminum alloys and brass has been studied. It has been found out that the amount of 30 to 40 wt % tungsten in the initial mixture ensures sintering of a tool composite with the most favorable phase composition for turning aluminum alloys and brass.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The paper addresses the effect of face roughness of cutting inserts made of diamond–tungsten carbide nanocomposite on cutting forces, vibration, and machined surface quality in finish turning of ...aluminum alloys and brass. The authors have substantiated the optimal cutting conditions to produce workpiece surfaces with the minimum roughness and waviness.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The U.S. Coast Guard and Federal Occupational Safety and Health Administration have identified the Alaskan offshore seafood processing industry as high-risk. This study used Coast Guard injury ...reports to describe patterns of traumatic injury among offshore seafood processors, as well as identify modifiable hazards.
From the reports, we manually reviewed and abstracted information on the incident circumstances, injury characteristics and circumstances, and vessel. Traumatic injury cases were coded using the Occupational Injury and Illness Classification System, and a Work Process Classification System. Descriptive statistics characterized worker demographics, injuries, and fleets.
One fatal and 304 nonfatal injuries among processors were reported to the Coast Guard during 2010–2015 across multiple fleets of catcher-processor and mothership vessels. The most frequently occurring injuries were: by nature of injury, sprains/strains/tears (75, 25%), contusions (50, 16%), and fractures (45, 15%); by body part affected, upper extremities (121, 40%), and trunk (75, 25%); by event/exposure resulting in injury, contact with objects and equipment (150, 49%), and overexertion and bodily reaction (76, 25%); and by source of injury, processing equipment and machinery (85, 28%). The work processes most frequently associated with injuries were: processing seafood on the production line (68, 22%); stacking blocks/bags of frozen product (50, 17%); and repairing/maintaining/cleaning factory equipment (28, 9%).
Preventing musculoskeletal injuries, particularly to workers' upper extremities and trunks, is paramount. Some injuries, such as serious back injuries, intracranial injuries, and finger crushing or amputations, had the potential to lead to disability.
Safety professionals and researchers can use the study findings to inform future intervention efforts in this industry. Hazard control measures should target: (a) overexertion from lifting and lowering objects and equipment; (b) equipment and boxes falling and striking workers; (c) workers being caught in running machinery during regular operations; and (d) slips, trips, and falls.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Abstract Background The macrolide sirolimus (rapamycin) selectively blocks translation of mRNAs containing a terminal 5′ oligopyrimidine (TOP) tract by altering the activity of mammalian target of ...rapamycin (mTOR) and inhibiting downstream mTOR pathway components involved in TOP mRNA translation. The skin disorder pachyonychia congenita (PC) is caused by mutations in the inducible keratins (K) including K6a, K6b, K16 and K17. Published sequence data suggest the 5′ untranslated regions of K6a and K6b mRNAs contain 5′ TOP motifs and therefore may be sensitive to rapamycin treatment. Objective Determine if mTOR inhibitors (rapamycin, temsirolimus or everolimus) are viable drug candidates for treatment of PC and other disorders caused by inappropriate expression of K6a and K6b. Methods 5′ RACE analysis was used to map the transcriptional start sites for K5, K6a, K6b, K14, K16 and K17. The sensitivity of these keratins to mTOR inhibitors was determined by Western and qPCR analysis following treatment of a human HaCaT keratinocyte cell line with rapamycin, temsirolimus or everolimus. A small off-label study was undertaken using orally administered rapamycin in three PC patients and the effects were monitored by clinical examination, photography, a validated Dermatology Life Quality Index (DLQI) and a pain and activity diary. Results Sequence comparison and 5′ RACE analysis of the 5′ untranslated regions of K6a and K6b revealed putative TOP regulatory elements. Treatment of a human HaCaT keratinocyte cell line with mTOR inhibitors (rapamycin, temsirolimus or everolimus) resulted in selective K6a repression. Furthermore, treatment of this HaCaT cell line with siRNAs targeting components of the mTOR pathway altered the levels of K6a expression. To test the ability of rapamycin to ameliorate PC symptoms, an off-label study was conducted. PC patient clinical responses to oral rapamycin showed a therapeutic response in callus character as well as subjective improvement. Of particular note, rapamycin greatly reduced the presence of painful cutaneous thromboses after reaching therapeutic serum levels. The well-known rapamycin side effects led to the early withdrawal of all of the patients from the study. Conclusion Rapamycin selectively blocks K6a expression in human keratinocytes. The improvement of symptoms in PC patients following rapamycin treatment suggests rapamycin (or rapamycin analogs) may be a therapeutic option, particularly if topical formulations can be developed that avoid the side effects associated with systemic administration.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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