Assessment of Technological Capabilities for Forming Al-C-B System Coatings on Steel Surfaces by Electrospark Alloying Method

In this paper, the possibility of applying the electrospark alloying (ESA) method to obtain boron-containing coatings characterised by increased hardness and wear resistance is considered. A new method for producing such coatings is proposed. The method consists in applying grease containing aluminium powder and amorphous boron to the surface to be treated and subsequently processing the obtained surface using the ESA method by a graphite electrode. The microstructural analysis of the Al-C-B coatings on steel C40 showed that the surface layer consists of several zones, the number and parameters of which are determined by the energy conditions of the ESA process. Durametric studies showed that with an increase in the discharge energy influence, the microhardness values of both the upper strengthened layer and the diffusion zone increased to W_p = 0.13 J, Hµ = 6487 MPa, and W_p = 4.9 J, Hµ = 12350 MPa, respectively. The results of X-ray diffraction analysis indicate that at the discharge energies of 0.13 and 0.55 J, the phase composition of the coating is represented by solid solutions of body-centred cubic lattice (BCC) and face-centred cubic lattice (FCC). The coatings obtained at W_p = 4.9 J were characterised by the presence of intermetallics Fe₄Al₁₃ and borocementite Fe₃ (CB) in addition to the solid solutions. The X-ray spectral analysis of the obtained coatings indicated that during the electrospark alloying process, the surface layers were saturated with aluminium, boron, and carbon. With increasing discharge energy, the diffusion zone increases; during the ESA process with the use of the discharge energy of 0.13 J for steel C40, the diffusion zone is 10–15 μm. When replacing a substrate made of steel C40 with the same one material but of steel C22, an increase in the thickness of the surface layer accompanied by a slight decrease in microhardness is observed as a result of processing with the use of the ESA method. There were simulated phase portraits of the Al-C-B coatings. It is shown that near the stationary points in the phase portraits, one can see either a slowing down of the evolution or a spiral twisting of the diffusion-process particle.     

Dietary restriction improves repopulation but impairs lymphoid differentiation capacity of hematopoietic stem cells in early aging

Dietary restriction (DR) improves health, delays tissue aging, and elongates survival in flies and worms. However, studies on laboratory mice and nonhuman primates revealed ambiguous effects of DR on lifespan despite improvements in health parameters. In this study, we analyzed consequences of adult-onset DR (24 h to 1 yr) on hematopoietic stem cell (HSC) function. DR ameliorated HSC aging phenotypes, such as the increase in number of HSCs and the skewing toward myeloid-biased HSCs during aging. Furthermore, DR increased HSC quiescence and improved the maintenance of the repopulation capacity of HSCs during aging. In contrast to these beneficial effects, DR strongly impaired HSC differentiation into lymphoid lineages and particularly inhibited the proliferation of lymphoid progenitors, resulting in decreased production of peripheral B lymphocytes and impaired immune function. The study shows that DR-dependent suppression of growth factors and interleukins mediates these divergent effects caused by DR. Supplementation of insulin-like growth factor 1 partially reverted the DR-induced quiescence of HSCs, whereas IL-6/IL-7 substitutions rescued the impairment of B lymphopoiesis exposed to DR. Together, these findings delineate positive and negative effects of long-term DR on HSC functionality involving distinct stress and growth signaling pathways.Experimental dietary restriction (DR) is based on a 10–30% reduction in food intake without leading to malnutrition (Omodei and Fontana, 2011). DR has been intensively studied and was shown to elongate the lifespan of Caenorhabditis elegans, Drosophila melanogaster, and rats (Fontana et al., 2010). Studies on inbred laboratory mice revealed that DR elongates lifespan in some mouse strains, whereas in others, the effects of DR were neutral or even resulted in lifespan shortening compared with ad libitum (AL)–fed controls (Harper et al., 2006). In long-lived nonhuman primates, two studies reported on the consequences of long-term DR on overall lifespan (Colman et al., 2009; Mattison et al., 2012). In both studies, DR did not result in a significant elongation of the lifespan compared with AL controls when all primates were included in the analysis (Colman et al., 2009; Mattison et al., 2012). These results stand in contrast to multiple studies having unambiguously documented beneficial effects of DR on health parameters and disease prevention in both murine models and primates, including suppression of cancer development, memory loss, hearing impairments, type 2 diabetes, hypertension, and heart disease (Shimokawa et al., 1993; Mattson, 2005; Cohen et al., 2009; Colman et al., 2009; Omodei and Fontana, 2011; Mattison et al., 2012).To better understand the effects of DR on health and lifespan, it is important to characterize the cellular consequences of DR at the level of adult tissue stem cells. Adult stem cells exist in many mammalian organs and tissues. Given that stem cells play essential roles in the maintenance of tissue homeostasis and tissue regeneration after damage, it is believed that age-related changes in stem cell function impact tissue aging (Dorshkind et al., 2009; Jones and Rando, 2011; Goldberg et al., 2015). Indeed, age-related declines in stem cell functionality occur in various tissues (Liu and Rando, 2011). However, the effects of DR on stem cell functionality and aging remain to be characterized in greater detail. It was reported that DR enhances muscle stem cell maintenance and activity to regenerate damaged muscle (Cerletti et al., 2012). In addition, it was shown that DR augments stem cell activity in the intestinal epithelium by stimulating mammalian target of rapamycin complex 1 (mTORC1) signaling in the Paneth cells that form a niche for intestinal stem cells (Yilmaz et al., 2012).In the hematopoietic system, DR ameliorated aging-associated increases in the self-renewal of phenotypic hematopoietic stem cells (HSCs) with reduced functionality as well as defects in the clearance of nonproliferative (senescent) and damaged T lymphocytes (Spaulding et al., 1997a; Chen et al., 1998, 2003; Ertl et al., 2008). However, DR-fed mice exhibited an enhanced susceptibility to infections indicative of impaired immune functions (Peck et al., 1992; Gardner, 2005; Kristan, 2007; Goldberg et al., 2015). Mechanistically, the effects of DR on HSC functionality remain incompletely understood but are influenced by genetic factors (Ertl et al., 2008).In this study, we analyzed the short- and long-term effects of adult-onset 30% DR on the capacity of HSCs and progenitor cells in maintaining hematopoietic repopulation and B lymphopoiesis in C57BL/6J mice. The study provides the first experimental evidence that long-term DR alters the lymphoid cell differentiation potential of HSCs and progenitor cells, resulting in immune defects in the context of prolonged bacterial infection. However, long-term DR from young adulthood to midlife improves the maintenance of the repopulation capacity of HSCs by enhancing stem cell quiescence. The study identifies distinct stress signaling factors (IL-6 and IL-7) and growth factors (insulin-like growth factor 1 [IGF1]) that contribute to both the positive and adverse effects of DR on HSC functionality.     

NF‐κB2/p100 deficiency impairs immune responses to T‐cell‐independent type 2 antigens

Formation of the splenic marginal zone (MZ) depends on the alternative NF‐κB signaling pathway. Recently, we reported that unrestricted activation of this pathway in NF‐κB2/p100‐deficient (p100^?/?) knock‐in mice alters the phenotype of MZ stroma and B cells. Here, we show that lack of the p100 inhibitor resulted in an expansion of both MZ B and peritoneal B‐1 cells. However, these cells failed to generate proliferating blasts in response to T‐cell‐independent type 2 (TI‐2) Ags, correlating with dampened IgM and absent IgG3 responses. This phenotype was in part due to increased activity of the NF‐κB subunit RelB. Moreover, p100^?/?→B6 BM chimeras were more susceptible to infection by encapsulated Streptococcus pneumoniae bacteria, pathogens that induce TI‐2 responses. In contrast to the TI‐2 defect, p100 deficiency did not impair immune responses to the TI‐1 Ag LPS and p100^?/? MZ B cells showed normal Ag transportation into B‐cell follicles. Furthermore, p100^?/? MZ B and B‐1 cells failed to respond to TI‐2 Ags in the presence of WT accessory cells. Thus, NF‐κB2/p100 deficiency caused a predominant B‐cell‐intrinsic TI‐2 defect that could largely be attributed to impaired proliferation of plasmablasts. Importantly, p100 was also necessary for efficient defense against clinically relevant TI‐2 pathogens.     

Spectroscopy of Deep Traps in Cu2S-CdS Junction Structures

Cu₂S-CdS junctions of the polycrystalline material layers have been examined by combining the capacitance deep level transient spectroscopy technique together with white LED light additional illumination (C-DLTS-WL) and the photo-ionization spectroscopy (PIS) implemented by the photocurrent probing. Three types of junction structures, separated by using the barrier capacitance characteristics of the junctions and correlated with XRD distinguished precipitates of the polycrystalline layers, exhibit different deep trap spectra within CdS substrates.     

Prediction of mortality in severely injured patients with facial bone fractures

Purpose

Identify the most common concomitant injuries associated with facial trauma, and compare the efficacy of various scoring systems in estimation of mortality risks in this category of patients.

Methods

The study evaluated patients with facial and concomitant injuries, who received the multidisciplinary treatment in a specialized trauma hospital. Values of New Injury Severity Score, Glasgow Coma Scale, Facial Injury Severity Scale, age, and length of hospital stay were statistically analysed to determine presence of relationships between these indicators and define factors that significantly associated with lethal outcome.

Results

During 6-year observation period, 719 patients were treated with multiple or combined maxillofacial trauma, brain injuries and polytrauma. Mainly with isolated midface bones (49.7%), pan-facial (34.6%), mandible (12.9%), and frontal bone and walls (2.8%) fractures. Mortality was (2.2%). The mortality rates in patients with severe pan-facial fractures were higher (p?=?0.008) than in single anatomical area (6% vs 1.5%). Age, GCS, and NISS were the most reliable indicator of lethal outcome.

Conclusion

Age, Glasgow Coma Scale and New Injury Severity Score main factors, that predicts lethal outcome with high accuracy. New Injury Severity Score value?≥?41 is a critical level for survival prognosis and should be considered in treatment planning and management of this category of patients.

     

Effect of the Construction of Carbon Fiber Plate Insert to Midsole on Running Performance

In this paper, to investigate the independent effect of the construction of the forefoot carbon-fiber plate inserted to the midsole on running biomechanics and finite element simulation, fifteen male marathon runners were arranged to run across a runway with embedded force plates at two specific running speeds (fast-speed: 4.81 ± 0.32 m/s, slow-speed: 3.97 ± 0.19 m/s) with two different experimental shoes (a segmented forefoot plate construction (SFC), and a full forefoot plate construction (FFC)), simulating the different pressure distributions, energy return, and stiffness during bending in the forefoot region between the SFC and FFC inserted to midsole. Kinetics and joint mechanics were analyzed. The results showed that the footwear with SFC significantly increased the peak metatarsophalangeal joint (MTPJ) plantarflexion velocity and positive work at the knee joint compared to the footwear with FFC. The results about finite element simulation showed a reduced maximum pressure on the midsole; meanwhile, not significantly affected was the longitudinal bending stiffness and energy return with the SFC compared to the FFC. The results can be used for the design of marathon running shoes, because changing the full carbon fiber plate to segment carbon fiber plate induced some biomechanical transformation but did not significantly affect the running performance, what is more, reducing the peak pressure of the carbon plate to the midsole by cutting the forefoot area of the carbon fiber plate could be beneficial from a long-distance running perspective for manufacturers.     

后房压力变化对虹膜变形的流固耦合有限元分析

目的：建立房水流动及虹膜变形的数学模型,定量分析因瞳孔阻滞造成前后房压差所引发的闭角型青光眼发病机制。方法：数值模拟研究。研究正常虹膜形状（虹膜-晶状体间隙为30 μm）和瞳孔几乎后粘连（虹膜-晶状体间隙为5 μm、2 μm）下的房水流动及虹膜变形,利用计算流体动力学数值求解房水流动,并基于单向流固耦合技术进行虹膜在流场作用力下变形的有限元分析。结果：30 μm的正常虹膜-晶状体间隙前后房的压力几乎相等;对于5 μm和2 μm的虹膜-晶状体间隙,后房比前房压力分别高31 Pa和815 Pa。利用乘幂函数对前后房压差与虹膜-晶状体间隙之间的关系进行拟合,发现当该间隙小于3 μm后,前后房压差将异速增加形成显著虹膜膨隆,导致虹膜表面与角膜接触,引发房角关闭。结论：从生物力学的角度分析虹膜膨隆与房水流动的相互作用特征,能进一步定量揭示原发性闭角型青光眼瞳孔阻滞发病机制。