The formation of intermetallics in dissimilar Ti6Al4V/copper/AISI 316 L electron beam and Nd:YAG laser joints

The welds of titanium alloys with steels suffer from the brittleness of resulting intermetallic compounds. In present study, we report the feasibility of Ti6Al4V to stainless steel AISI 316L welding through pure copper interlayer carried out by electron beam and pulsed Nd:YAG laser. The nature and the localization of intermetallic phases in these welds have been studied by SEM, EDS, XRD and microhardness measurements. The simplified scenario of weld formation has been proposed in order to understand the mechanism of weld formation and to explain the way local phase content determines the mechanical properties.It can be concluded that the insertion of 500 μm pure copper interlayer allows reducing but not suppressing the formation of brittle Ti–Fe and Ti–Cr-based phases. The local accumulation of Cu–Ti and Cu–Fe–Ti-based phases is less detrimental to the strength of the welds, which makes joining possible. The thickness of brittle regions is reduced due to short lifetime of the melt and compensated by the ductilizing effect of copper. The tensile strength of the welds is limited by brittleness of CuTi₂ + FeTi + α-Ti layer situated next to the solid Ti6Al4V.     

Polypropylene composites obtained from self‐reinforced hybrid fiber system

The purpose of the study was to obtain a composite material with the self‐reinforced structure, which processing provide increased mechanical properties. The composites used in presented work were prepared from the two types of fiber mixtures, both were based on polypropylene fibers, the difference was in used cellulose or wood flour filler. Composites were prepared using the hot compaction method. The presented research describes the effect of the composite composition and processing conditions. The results include the static tension measurements, tensile impact tests and thermal analysis, including: DSC and DMTA. The structure has been studies using the SEM observations. Results of presented studies confirm the self‐reinforcing effect in obtained hybrid composites. It provides in the comparison to the standard wood polymer composites to the higher level of material reinforcement with lower amount of natural filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43283.     

Respiratory Abnormalities in Parkinson’s Disease: What Do We Know from Studies in Humans and Animal Models?

Parkinson’s disease (PD) is the second most common progressive neurodegenerative disease characterized by movement disorders due to the progressive loss of dopaminergic neurons in the ventrolateral region of the substantia nigra pars compacta (SNpc). Apart from the cardinal motor symptoms such as rigidity and bradykinesia, non-motor symptoms including those associated with respiratory dysfunction are of increasing interest. Not only can they impair the patients’ quality of life but they also can cause aspiration pneumonia, which is the leading cause of death among PD patients. This narrative review attempts to summarize the existing literature on respiratory impairments reported in human studies, as well as what is newly known from studies in animal models of the disease. Discussed are not only respiratory muscle dysfunction, apnea, and dyspnea, but also altered central respiratory control, responses to hypercapnia and hypoxia, and how they are affected by the pharmacological treatment of PD.     

Nitrosamines and water

This paper provides an overview of all current issues that are connected to the presence of nitrosamines in water technology. N-nitrosodimethylamine (NDMA) is the most frequently detected member of this family. Nitrosamines became the hottest topic in drinking water science when they were identified as disinfection by-products (DBPs) in chloraminated waters. The danger that they pose to consumer health seems to be much higher than that from chlorinated DBPs. This review summarizes our contemporary knowledge of these compounds in water, their occurrence, and precursors of nitrosamines in drinking and wastewaters, in addition to attempts to remove nitrosamines from water. The paper also reviews our knowledge of the mechanisms of nitrosamine formation in water technology. The current, commonly accepted mechanism of NDMA formation during chloramination of drinking waters assumes that dichloramine reacts with dimethylamine, forms unsymmetrical dimethylhydrazine and further oxidizes to NDMA. The question to answer is which precursors are responsible for delivering the DMA moiety for the reaction since the presence of DMA in water cannot explain the quantities of NDMA that are formed. There are also reports that other oxidants that are commonly used in water technology may generate NDMA. However, the mechanisms of such transformations are unknown. Methods for the removal of nitrosamines from water are described briefly. However, the research that has been undertaken on such methods seems to be at an early stage of development. It is predicted that photolytic methods may have the greatest potential for technological application.     

Model investigations on the fluid flow in continuous casting moulds of wide dimensions

The control of the liquid metal flow and the damping of surface fluctuations are predominant objects connected with the operation of wide mould casters. Investigations on a full scale water model reveal that the casting speed, the immersion depth of the entry nozzle, and the lift gas injection rate have to be tuned carefully for the benefit of optimal flow conditions in the CC-mould. When casting conditions are changed, it is necessary to adjust the free parameters correspondingly in order to maintain smooth casting operation and high ranking strand quality.     

Inclusions in continuously cast steel slabs - numerical model and validation

A numerical model for liquid steel flow and inclusion transport and separation in continuous casting moulds is presented, which covers several features simultaneously. The free surface at the meniscus is computed; the submerged entry nozzle is discretised in detail to resolve the outlet geometry; gas injection through the SEN and its effect on liquid steel flow are considered; capture of inclusions within gas bubbles is covered in a simplified approach; the solidifying shell and the process of inclusion entrapment by the growing shell are simulated. Computed flow profiles are compared to experimental results on water and to measurements on liquid steel in a slab caster. Predicted inclusion profiles in solid slabs are compared to empirical findings from literature. Results of the model for various cases will be presented in a subsequent publication.     

Medium-energy ion scattering spectroscopy with a position-sensitive and time-resolving detector

A Si (1 0 0) sample covered with a thin Ho layer was measured with a three-dimensional medium-energy ion scattering spectrometer. The spectrometer is an extended version of a time-of-flight spectrometer for medium-energy ion scattering, equipped with a large position-sensitive detector. The device is used for composition depth profiling and crystal structure determination. The intensity distribution of detected particles was visualized to present medium-energy scattering phenomena. Circular shapes were observed in images created with part of the data containing particles scattered from the surfaces of the sample layers. Images show leading edges of “clouds” of arriving scattered particles were detected using the flat surface of the detector, integrated over 2 ns intervals. The center positions of shapes produced by particles scattered on Ho and Si atoms are different. This is explained by the different kinematic-factor dependences on scattering angle of particles scattered on Si and Ho atoms. The depth resolution of the time-of-flight spectra acquired with the full solid acceptance angle of the detector is limited by the kinematic spread. Using position information of detected particles from the detector, corrections for the kinematic spread and variations of flight path lengths were applied to spectra, increasing the depth resolution.     

Use of a customer satisfaction survey by health care regulators: a tool for total quality management

OBJECTIVES: To conduct a survey of health care providers to determine the quality of service provided by the staff of a regulatory agency; to collect information on provider needs and expectations; to identify perceived and potential problems that need improvement; and to make changes to improve regulatory services. METHODS: The authors surveyed health care providers using a customer satisfaction questionnaire developed in collaboration with a group of providers and a research consultant. The questionnaire contained 20 declarative statements that fell into six quality domains: proficiency, judgment, responsiveness, communication, accommodation, and relevance. A 10% level of dissatisfaction was used as the acceptable performance standard. RESULTS: The survey was mailed to 324 hospitals, nursing homes, home care agencies, hospices, ambulatory care centers, and health maintenance organizations. Fifty-six percent of provider agencies responded; more than half had written comments. The three highest levels of customer satisfaction were in courtesy of regulatory staff (90%), efficient use of onsite time (84%), and respect for provider employees (83%). The three lowest levels of satisfaction were in the judgment domain; only 44% felt that there was consistency among regulatory staff in the interpretation of regulations, only 45% felt that interpretations of regulations were flexible and reasonable, and only 49% felt that regulations were applied objectively. Nine of 20 quality indicators had dissatisfaction ratings of more than 10%; these were considered priorities for improvement. CONCLUSIONS: Responses to the survey identified a number of specific areas of concern; these findings are being incorporated into the continuous quality improvement program of the office.     

Metalorganic Vapor-Phase Epitaxy Growth Parameters for Two-Dimensional MoS<Subscript>2</Subscript>

The influence of the main growth parameters on the growth mechanism and film formation processes during metalorganic vapor-phase epitaxy (MOVPE) of two-dimensional MoS₂ on sapphire (0001) have been investigated. Deposition was performed using molybdenum hexacarbonyl and di-tert-butyl sulfide as metalorganic precursors in a horizontal hot-wall MOVPE reactor from AIXTRON. The structural properties of the MoS₂ films were analyzed by atomic force microscopy, scanning electron microscopy, and Raman spectroscopy. It was found that a substrate prebake step prior to growth reduced the nucleation density of the polycrystalline film. Simultaneously, the size of the MoS₂ domains increased and the formation of parasitic carbonaceous film was suppressed. Additionally, the influence of growth parameters such as reactor pressure and surface temperature is discussed. An upper limit for these parameters was found, beyond which strong parasitic deposition or incorporation of carbon into MoS₂ took place. This carbon contamination became significant at reactor pressure above 100 hPa and temperature above 900°C.