bluuebunny/crossref_metadata_2025 huggingface dataset:
FORMATION OF RESIDUAL STRESSES IN COMPOUND lAYER DURING GAS NITRIDING MEASURED BY IN SITU TECHNIQUE
Authors: Kreft U. , Hoffmann F. , Hirsch T. , Mayr P.
Published: January 2014

Residual stresses have a strong influence on the properties of nitrided parts. Therefore knowledge of their origin and magnitude is of great interest and aprerequisite if changes in the stresses are intended. From the relevant theories of residual stresses in gas nitrided materials it can be concluded that stresses which are generated during nitriding can be reduced by plastic deformation and increased during cooling from nitriding temperature to room temperature. The increase in residual stresses should be a result of the volume misfit generated by different thermal expansion coefficients of the compound layer and the steel matrix. The theories mentioned have not thus far been confirmed by experimental work. Therefore one aim of the investigations was to clarify the origin of residual stresses as well as the different influences on the formation of residual stresses, especially during cooling from nitriding temperature to room temperature. Previously, residual stresses of nitrided parts could only be measured after nitriding. In the present work it will be shown, for the first time, that residual stresses cansuccessfully be determined in situ during the gas nitriding process by a special nitriding device installed in an X-ray diffractometer.
Process modelling of thermal spray deposition of thermosets
Authors: Bao Y. , Gawne D. T.
Published: January 2014

Optimisation of thermal spraying, as for generic polymers, produces thermosets in the uncured condition with unsatisfactory engineering properties. The present paper develops a theoretical process modelfor thermoset reactive deposition, based on heat transfer mechanisms, which enables temperature profiles to be generated as a function of process variables. The model predicts that crosslinking can not take place in in flight precursor particles, isolated splats, or deposits without substrate preheating. It shows that the difficulty in achieving satisfactory properties is a result of the rapid heat flow to the substrate, which suppresses the crosslinking reaction. The model is applied to identify methods of enhancing the engineering properties of thermosets and indicates that substrate preheating, ceramic undercoats, and rapid curing agents can promote the curing reaction during thermal spraying. An experimental technique to evaluate the degree of crosslinking in the deposits from enthalpy determinations is developed. The experimental work, which consisted of differential scanning calorimetry and tribological measurements, is in agreement with the theoretical model and the predicted process route was successful in producing thermosets that were 85% cured in situ by reactive deposition.
Lifetime determining factors during thermal cycling of zirconia based thermal barrier coatings
Authors: Joshi S. V. , Srivastava M. P.
Published: January 2014

Plasma sprayed yttria stabilised zirconia (YSZ) coatings were investigated to assess the factors influencing their durability during thermal cycling. For any given powder, the best performance was found to be achieved at an optimum plasma arc current, all other spray parameters being held constant. The YSZ overlayer thickness was found to be an important lifetime determining factor. Use of a NiCoCrAlY bond coat instead of Ni–Cr led to a substantial improvement in coating lifetime, with the enhancement provided by NiCoCr AlY becoming more pronounced with increasing porosity level of the ceramic overlayer. A post-coating heat treatment was also found to be beneficial to coating longevity. The relative ranking of magnesium zirconate and YSZ coatings was found to depend upon the thermal cycle adopted during testing, which has important implications in designing accelerated tests to evaluate coating performance.
EFFECT OF RARE EARTH ELEMENTS ON PLASMA NITRIDING OF 38CrMoAI STEEL
Authors: Peng J. , Dong H. , Bell T. , Chen F. , Mo Z. , Wang C. , Peng Q.
Published: January 2014

Plaslna nitriding of steels has been intensively investigated and has found many applications in several industrial sectors owing to the excellent combination of properties obtained, i.e. good tribological performance and high fatigue strength. Although some preliminary research work has reported that rare earth elements can speed up most thermochemical treatments, little attention has been paid to the effect of these elements on the plasma assisted thermochemical processes. In the present investigation, plasma nitriding of 38CrMoAl steel has been carried out in order to investigate the effect of introducing rare earth elements on the process and on the structures and abrasive wear resistance of the resultant sUljace layers. Systematic characterisation of the surface layers has been perfonned elnploying optical and electron microscopy (morphology of worn surface), X-ray diffraction (phase identification), energy dispersive X-ray analysis (composition), and microhardness testing. Abrasive wear tests were also conducted using a wheel on wheel configuration with hard iron borides as an abrasive medium under different loads. The results showed that rare earth elements can effectively speed up the nitriding process, and this thicker nitrided case showed improved abrasive wear resistance. Based on the experimental results, the mechanism by which rare earth elements speed up the plasma nitriding process has been discussed in terms of sputtering induced defects (vacancies and dislocations), conjugation of rare earth species to these defects, and lattice distortions surrounding the rare earth atoms, which facilitate fast shortcircuit diffusion of nitrogen.
MICROSTRUCTURE AND PROPERTIES OF LASER REMELTED COBALT BASED AND NICKEL BASED PLASMA SPRAYED COATINGS
Authors: Wang K. , Liu J. , Han D.
Published: January 2014

The effect of laser remelting on the microstructure, porosity, and chemical homogeneity of cobalt based and nickel based alloy coatings plasma sprayed on stainless steel substrates has been investigated. Coating, nicrostructure and density were markedly improved by laser melting and much better chemical homogeneity was obtained. The micro hardness and corrosion resistance of the coatings were also enhanced significantly following laser melting.
LASER METAL FORMING: PROCESS FUNDAMENTALS
Authors: Gremaud M. , Wagnière I.-D. , Zryd A. , Kurz W.
Published: January 2014

Laser metal fornling (LMF) is an innovative application for lasers with industrial potential for small series production, rapid prototyping, or repair engineering. It consists in the production of full strength metallic engineering components using a three-dimensional laser cladding process. Prototypes produced by LMF can be used to test the performance and reliability aspects of a particular design and must therefore have physical and mechanical properties similar to those of the mass produced part. The LMF technique can also be used to repair metallic parts and improve their life cycle behaviour. The fundamental aspects of this free forming technique were investigated to contribute to the physical understanding and to better control of the process. To this end, only simple geometrical parts have been produced. It was found that the dimensions, the shape, the shape instabilities, and the surface quality of the final components depend on the melt dynamics and on the kinetics of oxide formation at the surface of the alloy. Process conditions leading to the production of high quality parts have been determined for materials including steels, Stellite 6, IN 625 superalloy, and tin. The parts produced exhibit microstructures consisting of fine columnar dendritic grains without porosity and with mechanical properties equal to those of cast material.
Production of duplex coatings by thermal spraying and nitriding
Authors: Nestler M. C. , Spies H.-J. , Herrmann K.
Published: January 2014

Limitations of surface treatments can be apparent under the complex loading experienced by engineering parts and components. These limitations can be removed by using duplex techniques. The process combination of thermal spraying and nitriding makes it possible to produce coatings with increased resistance for applications involving complex stress and loading conditions. The interactions between thermal spraying and nitriding have been investigated and both processes optimised to achieve improved properties of the compound coatings. Metallographic, X-ray, wear, and corrosion test results for the compound coatings are presented.
Tribological behaviour of ion deposited ZrN coatings on mild steel substrate
Authors: Sundararajan G. , Roy M. , Das D. K.
Published: January 2014

Though the tribological properties of PVD TiN coatings have been extensively documented and are fairly well understood, this is not the case for ZrN coatings. Recent investigations have indicated that Zr N has great potential for protective coatings in man y aeroengine components and also for specialised cutting tools. In view of this, the tribological behaviour of ZrN coatings has been characterised on a mild steel substrate. ZrN coatings, approximately 10 11m thick, were produced on a steel substrate by reactive ion nitriding. The microstructures of the coatings were characterised by SEM while the phase distribution was examined using XRD. Coating hardness was measured using a Shimadzu ultramicrohardness tester. The tribological behaviour of Zr N was studied and compared with that of the steel substrate. The solid particle erosion resistance and abrasive wear resistance of Zr N were evaluated and compared with those of the substrate using a room temperature erosion rig and a rubber wheel abrasive tester, respectively.
Composite coatings: Manufacture, properties, and applications
Authors: Steinhäuser S. , Wielage B.
Published: January 2014

The sUlface properties of structural components have a strong influence on their behaviour. In many cases such components are stressed in the surface region by a combination of mechanical, tribological, corrosive, and thermal factors. Under these circumstances, deposition of composite coatings can provide effective surface protection. Deposits can be coated on steel, light metals, ceramics, plastics, and other materials. Composite coatings consist of a metal matrix with, in general, non-metal solid particles or short fibres. The most important coating processes are electrochemical or electro less plating and thermal spraying. This paper reviews the manufacture, properties, and applications of composite coatings and summarises new developments in this field. Fine particles with diameters less than 100 nm are available and are investigated in connection with electroplating experiments. Thermal sprayed aluminium composite coatings on light metals have been manufactured and evaluated. Finally, thermal sprayed composite coatings with short fibres are described.
Bone ingrowth into micropores of hydroxyapatite coated titanium plates
Authors: Zhou P. , Hosonuma M. , Kobayashi T. , Mitsui H. , Akao M. , Aoki H.
Published: January 2014

An innovative thermal decomposition method has been used to coat hydroxyapatite (HA) on to porous Ti plates to judge its efficiency in promoting bone ingrowth. Canine implantation tests were carried out to determine the histologic features of the coating, which was as thin as 2μm. Micropores 50, 100, 200, and 300 11min diameter were made in both coated and uncoated Ti plates. The H A coated plates were characterised by chemical analysis, X-ray diffractometry (XRD), EDX, and SEM observations. Chemical analysis by ICP indicated that the Ca: P ratio of the hydroxyapatite coating was 1·65. The XRD patterns revealed that the coated layer consisted of HA and β- TCP (tricalcium phosphate) phases. Bone tissue reaction inside the pores was examined histologically at 2, 4, 8, and 16 weeks after implantation. The differences in ingrowth between the control and coated plates led to the conclusion that while there were similarities in such growth, the coated plates proved to have greater levels of better quality ingrowth. Initially, the larger 300 μmsized holes exhibited better ingrowth, but there were no evident differences in ingrowth between the pore sizes in the final analysis regardless of whether they were coated or uncoated.
Surface engineering to improve tribological performance of Ti–6Al–4V
Authors: Dong H. , Bloyce A. , Morton P. H. , Bell T.
Published: January 2014

A series of thermal oxidising treatments has been carried out on Ti–6Al–4V alloy at temperatures ranging from600 to 850°C to develop a new surface engineering technique for Ti–6Al–4V and other titanium alloys. Systematic characterisation of the thermal oxidation treated surface layers was performed using GDS, XRD, SEM, and nanoindentation testing. Ball on disc friction tests show that the coefficient offriction of a Ti–6Al–4V disc against an alumina ball was significantly reduced after oxidation treatment. The rolling–sliding wear resistance of Timetal 6–4 material against hardened 709M40 steel under lubricated conditions has been increased by thermal oxidation (TO) treatment to such an extent that it is even superior to that of the steel counterpart. The results also show that the electrochemical corrosion resistance in 3%NaCl solution isimproved by proper TO treatment.
Influence of laser hardening on mechanical properties of a low alloy steel
Authors: Putatunda S. K. , Nambiar M. , Clark N.
Published: January 2014

An investigation was carried out to examine the influence of laser hardening on the mechanical properties of 300M steel. The mechanical properties(including high cycle fatigue strength) of 300M steel surfaces hardened by several conventional techniques such as shot peening, carbonitriding, and induction hardening have been compared with the mechanical properties of CO2 laser hardened specimens. The effects of such sUlface coatings as manganese phosphate and colloidal graphite on the laser hardening were also examined. The influence of all these hardening methods on the nature and magnitude of the resulting residual stresses was studied. The results of the present investigation indicate that the induction hardening produces the largest improvement in high cycle fatigue strength. Laser hardened specimens with manganese phosphate coating also showed significant improvement in high cycle fatigue strength over untreated specimens. In contrast, the high cycle fatigue strength of the graphite coated laser treated specimens was lower than that of untreated specimens. Test results also show that laser hardening produced surface hardness comparable to that achieved by induction hardening. However, the ductility of the laser hardened specimens (both manganese phosphate and graphite coats) was significantly lower than that of the induction hardened specimens. The major problem appears to be the formation of a diffusion bonded phosphate layer on the interface of manganese phosphate coated specimens.The lower fatigue strength and ductility of the laser treated graphite coated specimens appear to be a result of surface melting. Induction hardening introduced significant amounts of compressive residual stresses into the surface of these specimens.
Adhesion of plasma sprayed Al2O3–TiO2 layer at high temperatures
Authors: Sasaki M. , Nakagawa M. , Miyazaki T. , Uraa R.
Published: January 2014

Three kinds of alumina–titania powder mixtures were produced by various manufacturing methods. The powderswere plasma sprayed on to grit blasted coppersubstrates. The plasma sprayed layers were investigated by thermal cycling from 1073 K to room temperature. Adhesion was evaluated by peeling tests in highfrequency vibration. Thepowders and sprayed layers were examined using scanning electron microscopy and optical microscopy to evaluate adhesion between the sprayed layers and substrates. The highest adhesion was obtained from the layers sprayed with clad alumina powder surrounded by titania on to a copper substrate which had been blasted with mixed grits 0·3–2·5 mm in size. These layers are less than 20 11mthick and contain several microcracks at about 10 11mintervals.
Thermal barrier coatings with two ZrO2 based ceramic layers
Authors: Sodeoka S. , Suzuki M. , Inoue T. , Ueno K.
Published: January 2014

A new thermal barrier coating (TBC) structure, composed of two ZrO2 based ceramic layers with different chemical composition on an MCrAlY bondcoating is proposed. In the double ceramic coatings, the lower layer consists of high strength ZrO2–Y2O3 and the upper layer of ZrO2–CeO2–Y2O3 with high heat shielding capacity. The new bilayer structure TBC was prepared by plasma spraying, and its properties, including thermal conductivity and thermal shock resistance, were evaluated. The thermal conductivity of the coatings showed good agreement with values calculated by the parallel plates model. The coatings also exhibited improved thermal shock resistance. This result is supported by FEM analysis, which revealed that tensile stress accompanying thermal shock is reduced and, in fact, applied only to the strong lower layer.
Wear of plasma nitrided high speed steel
Authors: Tier M. , Bloyce A. , Bell T. , Strohaecker T.
Published: January 2014

In the present work the effects of different plasma nitriding processes on the high speed steel AISI M2 were investigated, comparing the wear performance and the microstructure of the steel. Specimens were nitrided at temperatures between 450 and 550°C for between 18 min and 2 h using a gas composition of 5 or 25%N2, balance H2. The wear test was carried out using an Amsler machine and a wheel-fiat type test. X-ray diffraction analyses, chemical composition depth profiles by glow discharge optical spectroscopy, microhardness tests, and optical and scanning electron microscopy of the layers were performed. The specimens nitrided at 550°C showed spalling in wear tests indicating a brittle surface, while the specimens nitrided for 1 h at 450 and 500°C (25%N2) demonstrated reduced friction coefficients and adhesive wear.
Adhesion improvement mechanism of sol–gel silicone coatings
Authors: Thibault M. , Bavay J. , Hernandez J. , Leroy J.-M.
Published: January 2014

The sol-gel process is an original method for processing semi-organic thin films on steel sheets. Silicone coatings containing methyl and phenyl groups produced by the hydrolysis and condensation of alkoxysilanes have high thermal resistance and chemical stability. Though adhesion is minimal compared to other semi-organic coatings used on ferrous substrates, the addition of an appropriate organic polymer increases the flexibility and adhesion of the coating and enhances its capability for use on steel sheets. This adhesion improvement mechanism has been studied by specular and diffuse reflectance FTIR spectroscopy.
Adhesion mechanism of copper films deposited by magnetron sputtering on polyamide composites
Authors: Legois V. , Aucouturier M. , Ollivier E. , Darque-Darque E. , Macheto P.
Published: January 2014

This paper presents a study of the interface between Cu and a glass fibre reinforced PAMXD 6 polymer. Substrate surface chemistry was characterised before metallisation by spectroscopic techniques including Fourier transform infrared and X-ray photoelectron spectroscopy (XPS). Chemical bonding of Cu layers (20 nm to 2 11mthick) to the polymer was investigated by XPS (depth profiling, argon ion bombardment) and secondary ion mass spectrometry. The results showed that Cu reacts with the polymer, leading to the formation of a Cu-O-C like interfacial compound, and illustrated the influence of the evaporation pressure and temperature parameters on the interfacial structure and final quality of the film. The adhesion strength of the coating, obtained by z axis tensile tests (studs bonded to the PAMXD 6 with an epoxy glue), confirmed the interpretation of the analyses.
Electrodeposition conditions of Pb-Cd alloy for wear applications
Authors: Campillo B. , Genesca J. , Avila J. , Pere R. , Arganis C.
Published: January 2014

An electrolyte based on Pb and Cd perchlorate was developed and employed to produce adherent alloy deposits containing 10-20 wt-%Cd. The optimum experimental results for electroplated alloys were obtained from perchlorate solutions containing 208 g L−1 Cd and 40 g L−1 Pb at current densities of approximately 6 A cm−2. The performance of these solutions was strongly sensitive to the addition of organic agents such as resorcinol and pepsine. Initial wear tests were also carried out in order to evaluate deposit performance under various loading conditions.
Current trends in laser shock processing
Authors: Peyre P. , Scherpereel X. , Berthe L. , Fabbro R.
Published: January 2014

The physical and mechanical aspects of laser shock processing (LSP) with plasma confinement were investigated with the aim of establishing the state of the art and assessing possible applications. Using a pulsed Nd :glass laser, fundamental processing aspects were studied, such as the precise role played by surface protective coatings and laser impact area on shock loading. For instance, it was shown that Al based coatings could enhance the peak stress values experienced by iron based surfaces by up to 50%. Residual stresses were investigated as the main contributor for improving surface behaviour. Lastly, the beneficial effects of LSP were demonstrated through two applications of the process: improvement offatigue behaviour and pitting corrosion resistance of steels.
Fatigue damage monitoring of laser surface treated steel by X-ray diffraction methods
Authors: Olchini A. , Stamm H. , Marques F. Dos Santos
Published: January 2014

The evolution of fatigue damage in an austenitic stainless steel was investigated by metallographic and X-ray diffraction (XRD) methods. The experimental results confirm a previously developed idea based on X-ray line breadth measurements. According to this idea, the operating mechanism for fatigue damage is the progressive work hardening of the material which takes place preferentially at the surface and advances gradually into the bulk. Fatigue fracture is related to the attainment of a critical work hardening level at the surface. The so called integral breadth of the XRD line was taken as an estimate of work hardening. In the present work the X-ray line integral breadth was used to monitor the accumulated work hardening of laser surface treated and untreated specimens during fatigueand is proposed as a non-destructive fatigue damage parameter. It is also shown that the map of the surface damage resulting from integral breadth measurementson broken specimens gives iriformation about the microstructure and fatigue damage evolution. Particularly, the change in the damage accumulation after laser surface treatment is related to the microstructural changes caused by the treatment.
Analyses of laser and furnace treated sol–gel coatings
Authors: De Hosson J. T. M. , De Haas M.
Published: January 2014

A new method that allows thin films to be produced with almost any composition and degree of porosity by means of a combination of sol–gel and laser technology is explored. Results offurnace and laser treated TEOTi (tetraethylorthotitanate as sol precursor) coated silicon specimens are presented. From detailed X–ray analyses it appeared that the TEOTi derived sol–gel coatings experience crystallisation during furnace as well as laser treatment. The resulting TiO2 is present in two different tetragonal phases. As far as the residual stress measurements on the TEOTi derived sol–gel coatingsare concerned, it can be concluded that there is no significant triaxial stress state present in the coating, which justifies the biaxial stress analysis.
Effect of different compound layer and base material microstructures on microstrain and domain size of nitrided steel
Authors: Hirsch T. , Hoffmann F. , Mayr P.
Published: January 2014

The inhomogenous microstrains in thermochemically treated materials can be described by calculating average crystallite size (dolnain size) limited by lattice defects and the root mean squared lattice strains in the domain using XRD analysis. When nitriding under different process parameters, specimens were removed from the experiment after different nitriding times in order to investigate the domain sizes and the mean squared lattice strains in the compound layer as a function of nitriding time. Studies of depth profiles from the compound layer were of special interest. The nitriding potential KN, a characteristic value for the composition of the nitriding atmosphere and the formation of nitride phases, was varied from 0·5 to 0·7 at temperatures of 540 and 575°C in order to form γ nitride. Because of the low penetration depth in ferritic materials, Cu Kα radiation was used to obtain information close to the surface layers only. To obtain depth profiles of the examined specimens, thin material layers were removed in increments of 0.5, 1, or 2 μm by a sputtering process and the line profiles of the exposed surfaces were measured. Specimens were evaluated according to the methods of Warren and Averbach. Microstrain and domain size results show characteristic distributions with higher micros train values at the surface and at the compound layer/diffusion zone interface. These results can be correlated to the nitrogen and carbon contents in the compound layer. The dependence of microstructural properties on the various nitriding parameters is not significant.
Wear behaviour of diffusion and compound layers in nitrided steels
Authors: Molinari A. , Straffelini G. , Pellizzari M. , Pirovano M.
Published: January 2014

The wear behaviour of two nitrided steels was studied in order to evaluate the tribological properties of the compound layer and of the diffusion layer. The specimens were treated in different conditions, in order to obtain different microstructural and compositional characteristics of the nitrided surfaces. Concerning the diffusion layer, microstructural homogeneity tends to prevail over the microhardness profile in affecting wear resistance, since grain boundary carbonitrides worsen the mechanical properties and oxidation behaviour of the subsurface layers and contribute to abrasion of the counterface. As far as the compound layer is concerned, the effect of thickness and compactness is at least as significant, if not more so, than that of composition. The results demonstrate the importance of designing the microstructure of nitrided layers to maximise the wear resistance of the treated components.
Oxygen thermochemical treatment combined with DLC coating for enhanced loadbearing capacity of Ti–6Al–4V
Authors: Dong H. , Bloyce A. , Bell T.
Published: January 2014

In the present investigation, a novel duplex treatment of Ti–6Al–4V combining oxygen diffusion (OD) treatment with a carbon rich coating has been developed. A diamond like carbon (DLC) coating containing a small amount of titanium was deposited on to 0D treated Ti–6Al–4V using an unbalanced magnetron sputtering system. A graded intermediate layer of Ti/TiN /TiCN /TiC between the 0 D treated zone and the DLC coating was applied to facilitate good bonding. The loadbearing capacities of the duplex treated, as well as solely DLC coated, Ti–6Al–4V specimens were evaluated, both statically and dynamically using a friction monitored scratch tester, a ball on disc tribometer, and an indentation tester. It was found that both the staticand dynamic loadbearing capacities were significantly increased by a factor of 2·5 to 5 following the twofold treatment. Based onfurther fractographic examinations by high resolution SEM and finite element analysis, the excellent performance of the duplex system is discussed in terms of plastic deformation of the substrate, interface maximum shear stress, and coating/substrate interfacial integrity.
Kolsterising: Hardening of austenitic stainless steel
Authors: Rey O. , Jacquot P.
Published: January 2014

Kolsterising is a diffusion process for improving the tribological properties of austenitic and duplex stainless steels without affecting their corrosion resistance. The technique alters the characteristics of the base material in a thin layer by carbon enrichment in low temperature conditions in a gaseous environment. Three distinct processes have been developed; two for steels subject to different wear exposures and a third specifically for duplex stainless steels. Tribological and other properties of treated specimens are reported.
Fatigue crack growth mechanisms in Al–Si–Mg alloys
Authors: Lados D. A.
Published: January 2014

Owing to the increasing use of cyclically loaded cast aluminium components in automotive and aerospace applications, the fatigue and fatigue crack growth characteristics of aluminium castings are of great interest. Despite the extensive research efforts dedicated to this topic, a fundamental, mechanistic understanding of these alloys’ behaviour when subjected to dynamic loading is still lacking. The present research investigates the mechanisms active at the microstructure level during dynamic loading and failure of Al–Si–Mg alloys. Five model alloys were cast to isolate the contribution of constituent phases on fatigue resistance. The major constituent phases, α-Al dendrites, Al/Si eutectic phase, and Mg–Si strengthening precipitates were mechanistically investigated to relate microstructure to near-threshold crack growth D δKth and crack propagation regimes (regions II and III) for alloys of different Si composition/morphology, grain size, (secondary dendrite arm spacing) SDAS and heat treatment. A procedure to evaluate the actual fracture toughness from fatigue crack growth data has been successfully developed based on a complex elastic plastic fracture mechanics (EPFM/J-integral) approach. Residual stress–microstructure interactions, commonly overlooked by researchers in the field, are also comprehensively defined and accounted for both experimentally and mathematically. Revisions of ASTM E647 are in progress.
A systematic review of the psychometric properties of transition readiness assessment tools in adolescents with chronic disease
Authors: Zhang Lorena F , Ho Jane SW , Kennedy Sean E
Published: January 2014

Background

Health care transition of adolescents with chronic conditions may be unsuccessful when patients have not acquired the necessary skills and developmental milestones. It is therefore critical for health care providers to assess the readiness for transition of their adolescent patients. This is currently hindered by the lack of a recognised, well-established transition-readiness assessment tool.

Methods

We conducted a systematic review of all transition-readiness tools for adolescents with chronic medical conditions published in peer-reviewed journals. Tools were rated by the methodological quality of the validation studies, and the psychometric measurement qualities of each tool.

Results

Ten different assessment tools were identified. Seven targeted specific diseases and 3 tools were generic. Most tools were poorly validated with only one tool, the Transition Readiness Assessment Questionnaire (TRAQ) demonstrating adequate content validity, construct validity, and internal consistency.

Conclusion

The TRAQ was the best-validated transition-readiness tool, with additional benefits of disease-neutrality. Further research should focus on testing the predictive validity of this tool, and exploring correlation with transition-outcomes, in an international population.
Isolation of a novel amylase and lipase-producing Pseudomonas luteola strain: study of amylase production conditions
Authors: Khannous Lamia , Jrad Mouna , Dammak Mouna , Miladi Ramzi , Chaaben Nour , Khemakhem Bassem , Gharsallah Néji , Fendri Imen
Published: January 2014

An amylase and lipase producing bacterium (strain C2) was enriched and isolated from soil regularly contaminated with olive washing wastewater in Sfax, Tunisia. Cell was aerobic, mesophilic, Gram-negative, motile, non-sporulating bacterium, capable of growing optimally at pH 7 and 30°C and tolerated maximally 10% (W/V) NaCl. The predominant fatty acids were found to be C18:1ω7c (32.8%), C16:1ω7c (27.3%) and C16:0 (23.1%). Phylogenetic analysis of the 16S rRNA gene revealed that this strain belonging to the genus Pseudomonas. Strain C2 was found to be closely related to Pseudomonas luteola with more than 99% of similarity. Amylase optimization extraction was carried out using Box Behnken Design (BBD). Its maximal activity was found when the pH and temperature ranged from 5.5 to 6.5 and from 33 to 37°C, respectively. Under these conditions, amylase activity was found to be about 9.48 U/ml.
Absence of low back pain in the general population followed fortnightly over one year with automated text messages
Authors: Leboeuf-Yde Charlotte , Lemeunier Nadège , Wedderkopp Niels , Kjaer Per
Published: January 2014

Background

Over one year, the majority of patients with low back pain (LBP) from the secondary care sector could not report a single week without LBP and few could report a non-episode, defined as at least one month without LBP. Presumably, non-episodes would be more common in the general population. The aim of this study was to assess the usefulness of this definition of ´”non-episodes”, by studying their presence over one year in the general population. Specifically, we wanted to: 1) determine the prevalence of non-episodes, 2) identify the proportion of study participants who could be classified as being in a non-episode at the end of the observation period, and 3) estimate the proportion of participants classified as having at least two separate non-episodes.

Methods

Danes, aged 49/50, who previously participated in a population-based study on LBP received fortnightly automated text (SMS) messages over one year. Each time, participants reported the number of days with LBP in the preceding fortnight. Fortnights with 0 days of LBP were defined as ‘zero-fortnights’ and two such fortnights in a row (one month) were defined as a ‘non-episode’. Estimates are reported as percentages with their 95% confidence intervals in brackets.

Results

Two hundred and ninety-three people were invited to participate. Of these, 16 declined participation and 16 were excluded because they failed to return their text message at least 20 of the 26 times, leaving 261 in the current analyses. Of these, 11% (2-22) never reported a zero-fortnight. In all, 83% (78-88) had at least one non-episode throughout the study period and the proportion of participants classified as being in a non-episode at the end of the study was 59% (53-65). The percentage of individuals with at least two non-episodes was 52% (46-58).

Conclusions

It is possible to differentiate people from the general population as having or not having episodes of LBP using the definition of absence of LBP over one month as the measure. Non-episodes were far more common in the general population than in the secondary care sector, suggesting it to be a potentially useful definition in research.
Pregnancy-associated breast cancers are driven by differences in adipose stromal cells present during lactation
Authors: McCready Jessica , Arendt Lisa M , Glover Eugene , Iyer Vandana , Briendel Jerrica L , Lyle Stephen R , Naber Stephen P , Jay Daniel G , Kuperwasser Charlotte
Published: January 2014

Introduction

The prognosis of breast cancer is strongly influenced by the developmental stage of the breast when the tumor is diagnosed. Pregnancy-associated breast cancers (PABCs), cancers diagnosed during pregnancy, lactation, or in the first postpartum year, are typically found at an advanced stage, are more aggressive and have a poorer prognosis. Although the systemic and microenvironmental changes that occur during post-partum involution have been best recognized for their role in the pathogenesis of PABCs, epidemiological data indicate that PABCs diagnosed during lactation have an overall poorer prognosis than those diagnosed during involution. Thus, the physiologic and/or biological events during lactation may have a significant and unrecognized role in the pathobiology of PABCs.

Methods

Syngeneic in vivo mouse models of PABC were used to examine the effects of system and stromal factors during pregnancy, lactation and involution on mammary tumorigenesis. Mammary adipose stromal cell (ASC) populations were isolated from mammary glands and examined by using a combination of in vitro and in vivo functional assays, gene expression analysis, and molecular and cellular assays. Specific findings were further investigated by immunohistochemistry in mammary glands of mice as well as in functional studies using ASCs from lactating mammary glands. Additional findings were further investigated using human clinical samples, human stromal cells and using in vivo xenograft assays.

Results

ASCs present during lactation (ASC-Ls), but not during other mammary developmental stages, promote the growth of carcinoma cells and angiogenesis. ASCs-Ls are distinguished by their elevated expression of cellular retinoic acid binding protein-1 (crabp1), which regulates their ability to retain lipid. Human breast carcinoma-associated fibroblasts (CAFs) exhibit traits of ASC-Ls and express crabp1. Inhibition of crabp1in CAFs or in ASC-Ls abolished their tumor-promoting activity and also restored their ability to accumulate lipid.

Conclusions

These findings imply that (1) PABC is a complex disease, which likely has different etiologies when diagnosed during different stages of pregnancy; (2) both systemic and local factors are important for the pathobiology of PABCs; and (3) the stromal changes during lactation play a distinct and important role in the etiology and pathogenesis of PABCs that differ from those during post-lactational involution.
The effect of glutamine therapy on outcomes in critically ill patients: a meta-analysis of randomized controlled trials
Authors: Chen Qi-Hong , Yang Yi , He Hong-Li , Xie Jian-Feng , Cai Shi-Xia , Liu Ai-Ran , Wang Hua-Ling , Qiu Hai-Bo
Published: January 2014

Introduction

Glutamine supplementation is supposed to reduce mortality and nosocomial infections in critically ill patients. However, the recently published reducing deaths due to oxidative stress (REDOX) trials did not provide evidence supporting this. This study investigated the impact of glutamine-supplemented nutrition on the outcomes of critically ill patients using a meta-analysis.

Methods

We searched for and gathered data from the Cochrane Central Register of Controlled Trials, MEDLINE, Elsevier, Web of Science and ClinicalTrials.gov databases reporting the effects of glutamine supplementation on outcomes in critically ill patients. We produced subgroup analyses of the trials according to specific patient populations, modes of nutrition and glutamine dosages.

Results

Among 823 related articles, eighteen Randomized Controlled Trials (RCTs) met all inclusion criteria. Mortality events among 3,383 patients were reported in 17 RCTs. Mortality showed no significant difference between glutamine group and control group. In the high dosage subgroup (above 0.5 g/kg/d), the mortality rate in the glutamine group was significantly higher than that of the control group (relative risk (RR) 1.18; 95% confidence interval (CI), 1.02 to 1.38; P = 0.03). In 15 trials, which included a total of 2,862 patients, glutamine supplementation reportedly affected the incidence of nosocomial infections in the critically ill patients observed. The incidence of nosocomial infections in the glutamine group was significantly lower than that of the control group (RR 0.85; 95% CI, 0.74 to 0.97; P = 0.02). In the surgical ICU subgroup, glutamine supplementation statistically reduced the rate of nosocomial infections (RR 0.70; 95% CI, 0.52 to 0.94; P = 0.04). In the parental nutrition subgroup, glutamine supplementation statistically reduced the rate of nosocomial infections (RR 0.83; 95% CI, 0.70 to 0.98; P = 0.03). The length of hospital stay was reported in 14 trials, in which a total of 2,777 patients were enrolled; however, the patient length of stay was not affected by glutamine supplementation.

Conclusions

Glutamine supplementation conferred no overall mortality and length of hospital stay benefit in critically ill patients. However, this therapy reduced nosocomial infections among critically ill patients, which differed according to patient populations, modes of nutrition and glutamine dosages.
Inhibition of mesenchymal stromal cells by pre-activated lymphocytes and their culture media
Authors: Valencic Erica , Loganes Claudia , Cesana Stefania , Piscianz Elisa , Gaipa Giuseppe , Biagi Ettore , Tommasini Alberto
Published: January 2014

Introduction

Despite having a proven immunosuppressive potential in vitro, human mesenchymal stromal cells (MSCs) are reported to display variable efficacy in vivo and, in fact, their proven benefit in the clinical practice is still limited and controversial.

Methods

The interplay between clinical grade MSCs and pre-activated donor lymphocytes or selected lymphocyte subsets was studied in vitro. The kinetics of MSC growth and viability was evaluated by adhesion-dependent changes of culture plate impedance and biochemically by a colorimetric assay. Activation of natural killer (NK) cells was assessed as well, using a flow cytometry assay.

Results

A strong inhibition of MSC growth was rapidly induced by the addition of pre-activated lymphocytes but not of resting lymphocytes. Inhibition seems not to be attributable to a single cell population, as similar results can be obtained by depleting NK cells or by using either selected CD4+ or CD8+ lymphocytes. In addition, conditioned medium (CM) from activated lymphocytes was able to inhibit MSC growth in a dose-dependent manner. Furthermore, licensing with IFN-γ partially protected MSCs from pre-activated lymphocytes but not from their CM. These results suggest an inhibitory role of lymphocyte-activation-derived substances. However, the identification of a single molecule responsible for MSC inhibition remained elusive, even if preliminary experiments showed that ATP and, to a lesser extent, TNF-α might play a role.

Conclusions

These results suggest that survival of MSCs can be affected by soluble mediators released by activated lymphocytes. Thus it can be hypothesized that MSC immunosuppressive action in vivo could be impaired by ongoing immune activation through the release of inflammatory mediators.
Palladium-doped Nanogold Microspheres as Nanocatalysts for Enzyme-free Electrochemical Immunosensing of Low-abundance Protein
Authors: Li Guang-Zhou , Tang Dian-Ping
Published: January 2014

Palladium-doped nanogold microspheres were for the first time utilized as nanocatalysts and peroxidase mimics for development of enzyme-free electrochemical immunosensing with sensitivity enhancement.
DataUp: A tool to help researchers describe and share tabular data
Authors: Strasser Carly , Kunze John , Abrams Stephen , Cruse Patricia
Published: January 2014

Scientific datasets have immeasurable value, but they lose their value over time without proper documentation, long-term storage, and easy discovery and access. Across disciplines as diverse as astronomy, demography, archeology, and ecology, large numbers of small heterogeneous datasets (i.e., the long tail of data) are especially at risk unless they are properly documented, saved, and shared. One unifying factor for many of these at-risk datasets is that they reside in spreadsheets.

In response to this need, the California Digital Library (CDL) partnered with Microsoft Research Connections and the Gordon and Betty Moore Foundation to create the DataUp data management tool for Microsoft Excel. Many researchers creating these small, heterogeneous datasets use Excel at some point in their data collection and analysis workflow, so we were interested in developing a data management tool that fits easily into those work flows and minimizes the learning curve for researchers.

The DataUp project began in August 2011. We first formally assessed the needs of researchers by conducting surveys and interviews of our target research groups: earth, environmental, and ecological scientists. We found that, on average, researchers had very poor data management practices, were not aware of data centers or metadata standards, and did not understand the benefits of data management or sharing. Based on our survey results, we composed a list of desirable components and requirements and solicited feedback from the community to prioritize potential features of the DataUp tool. These requirements were then relayed to the software developers, and DataUp was successfully launched in October 2012.
Life of sculptures in Kuntsevo manor
Authors: Прохоров Михаил , Prokhorov Mikhail
Published: January 2014

History of formation and development of garden and park ensemble in Kuntsevo for XVII century and the beginning of XX century is considered in the article. Particular attention is paid to main sculptures and memorial obelisks of famous park pointing readers up on time periods of their construction and following life.
Exploiting Erraticism in Search
Authors: Fischetti Matteo , Monaci Michele
Published: January 2014

High sensitivity to initial conditions is generally viewed as a drawback of tree search methods because it leads to erratic behavior to be mitigated somehow. In this paper we investigate the opposite viewpoint and consider this behavior as an opportunity to exploit. Our working hypothesis is that erraticism is in fact just a consequence of the exponential nature of tree search that acts as a chaotic amplifier, so it is largely unavoidable. We propose a bet-and-run approach to actually turn erraticism to one's advantage. The idea is to make a number of short sample runs with randomized initial conditions, to bet on the “most promising” run selected according to certain simple criteria, and to bring it to completion. Computational results on a large testbed of mixed integer linear programs from the literature are presented, showing the potential of this approach even when embedded in a proof-of-concept implementation.
Development of Antimicrobial Competencies and Training for Staff Hospital Pharmacists
Authors: Crader Marsha F.
Published: January 2014

Antimicrobial stewardship is an important component in health care outcomes of all patients. Many institutions are seeking the best methods to incorporate antimicrobial stewardship strategies into their hospitals including pharmacy services. Multiple factors should be considered when beginning or expanding an antimicrobial stewardship program. The purpose of this article is to discuss the development of basic antibiotic competencies and training for staff pharmacists in a community hospital. The article includes an assessment of pharmacists’ knowledge pre education and post education, perception of benefits from an antibiotic education program, and learning needs and preferences.
Ferric Carboxymaltose
Authors: Cada Dennis J. , Levien Terri L. , Baker Danial E.
Published: January 2014

Each month, subscribers to The Formulary Monograph Service receive 5 to 6 well-documented monographs on drugs that are newly released or are in late phase 3 trials. The monographs are targeted to Pharmacy & Therapeutics Committees. Subscribers also receive monthly 1-page summary monographs on agents that are useful for agendas and pharmacy/nursing in-services. A comprehensive target drug utilization evaluation/medication use evaluation (DUE/MUE) is also provided each month. With a subscription, the monographs are sent in print and are also available on-line. Monographs can be customized to meet the needs of a facility. A drug class review is now published monthly with The Formulary Monograph Service. Through the cooperation of The Formulary, Hospital Pharmacy publishes selected reviews in this column. For more information about The Formulary Monograph Service, call The Formulary at 800-322-4349. The January 2014 monograph topics are obinutuzumab, anti-inhibitor coagulant complex, macitentan, riociguat, and conjugated estrogens/bazedoxifene. The DUE/MUE is on conjugated estrogens/bazedoxifene.