New strategies for intraoperative myocardial protection

In the past, most strategies for intraoperative myocardial protection were developed in models using nondiseased adult hearts from various animal species. In the clinical setting, however, myocardial status in cardiac patients may be quite different and there is a need to adapt our current protective strategies to the actual pathophysiological status of the heart. In the immature heart as well as in the senescent heart, current protective techniques have been shown to be deficient and further research is required. New insights have been gained into the pathophysiological processes underlying chronic ischemic left ventricular dysfunction in the "hibernating" myocardium. It has been shown that viability in these hearts is associated with subcellular alterations related to dedifferentiation of the myocytes. This finding explains the delayed recovery in function of these hearts after revascularization and the need for intraoperative protective strategies focusing on the prevention of stunning in the nonhibernating segments. Tepid continuous retrograde blood cardioplegia is suggested as the optimal technique. Unraveling the mechanisms of preconditioning in the heart and understanding endogenous myocardial protection may provide clues for novel cardioprotective techniques. Adenosine itself may be used as an adjunct to cardioplegia, and treatment with adenosine regulating agents or nucleoside transport inhibitors shows promising results. Like adenosine, other hyperpolarizing agents (potassium-channel openers) are suggested for arrest of the heart instead of the depolarizing agents commonly used in cardioplegia. Finally, the role of Na(+)-H+ exchange in the development of ischemic and postischemic injury has become more clear. By the use of a new selective Na(+)-H+ exchange inhibitor, postischemic contracture can be dramatically reduced and contractility improved. This opens prospective approaches in emergency coronary bypass surgery for evolving myocardial infarction.     

Composites of hydroxyapatite and bisphosphonate: properties and alveolar bone response

A composite was made by adsorption of the bisphosphonate [(3-dimethylamino-1-hydroxypropylidene)-1,1-bisphosphonate; dimethyl-APD] into an hydroxyapatite (HA) tube. Adsorbed dimethyl-APD did not change the bulk properties of the HA tube but the surface properties were altered. The amount of 0.1 mmol/L dimethyl-APD adsorbed into the HA tube was 0.78 ( ± 0.20) g after 4 weeks. The composite tube of HA and dimethyl-APD placed after extraction of teeth in the premolar regions of dogs were biocompatible, stable and bonded strongly and intimately to the alveolar bone. Although there was no bone resorption around the composite tubes, no conclusion can be drawn yet from this study as far as local inhibition of alveolar bone resorption is concerned.     

Simulation analysis and experimental verification of coal suction characteristics of the new railway tunnel fallen coal dust collection device北大核心CSCD

Due to air turbulence, large areas of coal will fall when the special coal-transportation trains pass the tunnel exits and entrances. Aiming at the problems of low efficiency and high cost of manual cleaning for long distance coal cleaning in the tunnel, a new railway tunnel fallen coal dust collection device which was composed of a main conveying coal feeding pipe and multiple branch pipes of coal suction was designed. It was used to clean the small particles and lightweight railway tunnel fallen coal. Firstly, the gas-solid two-phase flow model based on the Euler-Lagrange approach for the design of the main conveying coal feeding pipe was established in the coal conveying pipelines. Secondly, the effect of the coal particles' incident angle and multiple branch pipe spacing on the main coal conveying pipe flow field, which was based on Fluent finite element simulation software, was studied. What was more, the optimal angle of incidence and the optimal value of the number of branch coal suction pipe, which was installed on the main conveying pipe, were analyzed. Finally, the finite element simulation was verified by field test. Simulation and experimental results showed that it was more conducive to the railway tunnel fallen coal transportation when coal particles' incident angle was less than 45° and the branch pipe spacing was in the vicinity of 750 mm. For that when incident angle was less than 45°, the main conveying coal pipe pressure-drop became weaker and particle flow could obtain large horizontal transport velocity. And when the branch pipe spacing was in the vicinity of 750 mm, the horizontal transport velocity had a smaller fluctuation range and the transportation of coal was larger than that of the other groups. The research results are of great significance to improve the structure of the main conveying coal pipe, increase the efficiency of tunnel coal conveying and optimize the railway tunnel coal dust collection device.     

Wire + Arc Additive Manufacturing

Depositing large components (>10?kg) in titanium, aluminium, steel and other metals is possible using Wire + Arc Additive Manufacturing. This technology adopts arc welding tools and wire as feedstock for additive manufacturing purposes. High deposition rates, low material and equipment costs, and good structural integrity make Wire+Arc Additive Manufacturing a suitable candidate for replacing the current method of manufacturing from solid billets or large forgings, especially with regards to low and medium complexity parts. A variety of components have been successfully manufactured with this process, including Ti–6Al–4V spars and landing gear assemblies, aluminium wing ribs, steel wind tunnel models and cones. Strategies on how to manage residual stress, improve mechanical properties and eliminate defects such as porosity are suggested. Finally, the benefits of non-destructive testing, online monitoring and in situ machining are discussed.     

Enhanced mortar approach to characterize the effect of reclaimed asphalt pavement on virgin binder true grade

The asphalt community seeks a solvent-free method to determine the properties of RAP binder and those of its blends with virgin binders. A promising approach is to test mortars composed of fine fractions of RAP and a virgin binder, and to calculate grade change rate (GCR) to predict blended binder true grade at any binder replacement rate (BRR). However, the existing mortar approach underestimates the effect of RAP on binder grade, particularly at high temperatures. This study identified the use of a shift factor in the existing method as the source of underestimations. An alternative data analysis method was developed, which eliminates the shift factor by using the relationship between binder and mortar properties. Dynamic shear rheometer tests were conducted on a total of 12 mortar combinations, including 4 virgin binders and 3 RAP sources at a BRR of 15%, and then, RAP GCR values were determined by following both the existing and the alternative methods. Satisfactory comparisons were only observed between grades predicted with the alternative method and measured values of manual RAP binder blends: the average difference was lower than 1 °C for BRR of 15 and 30%, and < 4 °C for BRR of 100%. This not only validated the alternative method but also substantiated that RAP GCR is constant, i.e., the grade of RAP blends linearly increased with BRR. Further evaluation of the enhanced mortar approach is recommended at intermediate and low temperatures as well as with blends including recycled asphalt shingles.     

Surface energy-mediated fibronectin adsorption and osteoblast responses on nanostructured diamond

Nanostructured diamond have potential applications in many biomedical related fields and demonstrated extraordinary capacity to influence cellular responses. Studying the surface property of nanodiamond and its influence to protein adsorption and subsequent cellular responses along with the mechanism behind such capacity becomes more important. Here the role of surface energy associated with nanostructured diamond in modulating fibronectin and osteoblast(OB, bone forming cells) responses was investigated. Nanocrystalline diamond(NCD) and submicron crystalline diamond(SMCD) films with controllable surface energy were prepared by microwave-enhanced plasma chemical vapor deposition(MPCVD) techniques. Fibronectin adsorption on the diamond films with varied surface energy values was measured via the enzyme-linked immunosorbent assay(ELISA) and the relationship between the surface energy and fibronectin adsorption was studied. The result indicated that fibronectin adsorption on nanostructured surfaces was closely related to both surface energy and material microstructures. The spreading and migration of OB aggregates(each containing 30–50 cells) on the NCD with varied surface energy values were also studied. The result indicates a correlation between the cell spreading and migration on nanodiamond and the surface energy of nanostructured surface.     

A review on mechanisms and recent developments of nanomaterials based carbon fiber reinforced composites for enhanced interface performance

Carbon fiber reinforced composites have attracted lots of attention in many fields. However, on account of the poor infiltration of resin to carbon fiber, the weak interface performance between fiber and resin has been restricting the interface properties of composites. In recent progress, the review attaches more importance to the introduction of the third phase monomer, which mainly uses physical and chemical methods to assemble nanomaterials (such as carbon nanotubes, graphene, etc.) on the carbon fiber surface to modify the interface structure of the carbon fiber reinforced composites, and all of them have been demonstrated in this paper. Furthermore, the effects of introducing nanomaterials on the structure of the fiber/resin interface and the relationship between multi-scale interface structure and properties have been investigated. It can be seen that the design idea of researchers mainly uses one or more theories to improve the interface properties of carbon fiber reinforced composites, such as transition layer, chemical bonding, mechanical interlocking, infiltration, diffusion, and adsorption. In brief, this work provides some novel insights for the preparation of carbon fiber reinforced composites with excellent interlaminar shear strength.     

Prevalence and incidence of hand dermatitis in hairdressing apprentices: results of the POSH study. Prevention of occupational skin disease in hairdressers

OBJECTIVE: Occupational skin changes in hairdressers are very common. Morbidity, however, has not yet been quantified precisely. METHODS: A cohort of 2,352 hairdressing apprentices (of the 2,570 invited to participate, i.e., 91.5% response) was prospectively followed for the duration of their vocational training (3 years) by three examinations. Three waves (years) were recruited in 1992, 1993, and 1994 from 15 vocational training schools in northwestern Germany. RESULTS: The point prevalence of (mostly slight) irritant skin changes of the hands increased from 35.4% in the initial examination to 47.5% in the intermediate examination and to 55.1% in the final examination. Given a more conservative definition of a case of "hand dermatitis," these estimates were 12.9%, 23.5%, and 23.9%, respectively. Altogether, 34.3 and 15.2 cases of "skin changes (any degree)" and "hand dermatitis," respectively, in 100 person-years were observed during the study period. The incidence rate, i.e., the number of newly diseased study participants in relation to the person-time at risk contributed, decreased in the course of the study. The proportion of dropouts until final follow-up was 51.8%. CONCLUSION: The present results appear to lie in a range with those found in other, much smaller cohort studies. However, comparison of the results is hampered either by the lack of a clear definition or by a different definition of "person-time at risk" or "a case of hand dermatitis." As compared with an external control group of office apprentices, the incidence was several times higher in hairdressing apprentices, which points to the high risk for skin damage in this occupation.