Correlation between in vivo stresses and oxidation of UHMWPE in total hip arthroplasty

The possibility of in vivo, stress-induced oxidation in orthopaedic UHMWPE has been investigated. EtO sterilised, uncrosslinked UHMWPE liners, explanted or shelf-aged, have been collected. Linear wear and wear rate were assessed and FTIR spectroscopy was employed to detect oxidation and to build up oxidation products spatial maps across the liners section. Oxidation profiles have been compared to stress distribution profiles, resulting from a FE analysis conducted on the same liners geometries and couplings. It was found that oxidised and stressed areas followed the same asymmetrical, localized distribution profile. It was therefore possible to establish a correlation between stressed areas and observed oxidation.     

The high-temperature behaviour of PuPO4 monazite and some other related compounds

Thermal behaviour and lattice parameters of monazites MPO₄ (M³⁺ = Ce³⁺, Nd³⁺ and Pu³⁺) and cheralite CaTh(PO₄)₂ were studied using high-temperature X-ray diffraction. Heat treatment under inert atmosphere caused the decomposition of PuPO₄ and CaTh(PO₄)₂ into the corresponding oxides above 1473 K. The influence of the cation type within the crystallographic structure on the thermal expansion coefficient and the possible cation substitutions are discussed in the frame of nuclear waste management.     

Relaxation as a factor in semantic desensitization.

Assigned 32 female undergraduates with spider phobias to 1 of 4 groups: semantic desensitization (SD) and relaxation, SD and no relaxation, control-relaxation, and control-no relaxation. SD failed to promote modification of evaluative meanings evoked by the feared object. There appears to be a critical need to reassess the effectiveness of SD with other populations displaying varying types and amounts of fear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Photoelectron microscopy of plastic zone around a fatigue crack

The photoelectron emission from a metal is enhanced by fatigue cycling. This increase, which is often referred to as exoelectron emission, has been observed directly in a photoelectron microscope. The increase of emission results primarily from the rupturing of the thin surface oxide, thereby revealing a fresh metal surface of lower work function. During the propagation of a fatigue crack there are two sources of exoelectrons. 1)The crack itself, which emits very strongly and is easily identified. 2) The deformation generated in the nearby material,i.e. the plastic zone. In addition, the active portion of the plastic zone at the crack tip may be distinguished from the relatively inactive wake of deformed material.     

Farm typologies,soil fertility variability and nutrient management in smallholder farming in Sub-Saharan Africa

Farm typologies are a useful tool to assist in unpacking and understanding the wide diversity among smallholder farms to improve targeting of crop production intensification strategies. Sustainable crop production intensification will require the development of an array of nutrient management strategies tailored to farm-specific conditions, rather than blanket recommendations across diverse farms. This study reviewed key literature on smallholder farm typologies focusing on three countries (Kenya, Malawi and Zimbabwe), to gain insights on opportunities for crop production intensification, and the importance of developing farm-specific nutrient management practices. Investigations on farm typologies have done well in highlighting the fundamental differences between farm categories, with 3–5 typologies often adequate to represent the wide differences in resource endowment. Resource-endowed farmers have ready access to large quantities of manure and mineral fertilizers, which contribute to higher soil fertility and crop productivity on their farms. Resource-constrained households use little or no manure and mineral fertilizers, and have limited capacity to invest in labour-demanding soil fertility management technologies. These farmers often have to rely on off-farm opportunities for income that are largely limited to selling unskilled labour to their resource-endowed neighbors. The variability in management practices by farmers has resulted in three main soil fertility classes that can be used for targeting soil fertility management technologies, characterized by potential response to fertilizer application as: (1) low-responsive fertile fields that receive large additions of manure and fertilizer; (2) high-responsive infertile fields that receive moderate nutrient applications; (3) poorly responsive degraded soils cultivated for many years with little or no nutrient additions. The main conclusions drawn from the review are: (1) resource constrained farmers constitute the widest band across the three countries, with many of the farmers far below the threshold for sustainable maize production intensification and lacking capacity to invest in improved seed and fertilizer, (2) farm sizes and livestock ownership were key determinants for both farmer wealth status and farm productivity, and (3) soil organic carbon and available P were good indicators for predicting previous land management, that is also invariably linked to farmer resource endowment.     

Field-Effect Mobility,Morphology and Electroluminescence of a Semiconductor Based on a DPP?Quaterfluorene Quadrupolar Linear Conjugated System

An organic semiconductor, expressed as a quadrupolar linear conjugated system ( DPP Linear-c ), consisting of a 1,4-diketopyrrolo[3,4-c]pyrrole (DPP) central unit and two quaterfluorenylphenyl arms at the 3- and 6-positions of the DPP fragment, is studied in organic field-effect transistors (OFETs). The strong propensity of DPP Linear-c to aggregate in the solid state favours the hole mobility of the semiconductor due to the alignment of HOMOs in the aggregates. The fabrication of OFETs from this novel p-type semiconductor is reported, using different dielectrics to evaluate their effect on the overall device performance. Despite its aggregation, DPP Linear-c remains luminescent in the solid state. Electroluminescence of a non-optimised OLED fabricated from this material is demonstrated.     

Electrical and mechanical tuning of 3D printed photopolymer–MWCNT nanocomposites through in situ dispersion

An electric field-assisted in situ dispersion of multiwall carbon nanotubes (MWCNTs) in polymer nanocomposites, fabricated through stereolithography three-dimensional (3D) printing technique, was demonstrated. The introduction of MWCNTs increased the elasticity modulus of the polymer resin by 77%. Furthermore, the use of an electric field for in situ MWCNT dispersion helped improving the average elongation at break of the samples with MWCNTs by 32%. The electric field also increased the ultimate tensile strength of the MWCNT reinforced nanocomposites by 42%. An increase of over 20% in the ultimate tensile strength of in situ dispersed MWCNT nanocomposites over the pure polymer material was observed. Finally, it was demonstrated that the magnitude and direction of the electrical conductivity of MWCNT nanocomposites can be engineered through the application of in situ electric fields during 3D printing. An increase of 50% in the electrical conductivity was observed when MWCNTs were introduced, while the application of the electric field further improved the electrical conductivity by 26%. The presented results demonstrated the feasibility of tuning both electrical and mechanical properties of MWCNT reinforced polymer nanocomposites using in situ electrical field-assisted 3D printing. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47600.     

Detection of short-lived electrogenerated species by Raman microspectrometry

Raman microprobe spectrometry has been applied to the characterization of unstable species generated electrochemically at a microelectrode (radius in the 10 microm range). The ability of the spectroelectrochemical method to detect short-lived intermediates is directly related to its capability to probe small volumes. Raman microprobe spectrometry is appropriate for electrochemical applications because it allows the analysis of approximately 1 microm3 of solution. In spectroelectrochemical experiments, such a volume corresponds to a reaction layer of 1 microm thickness. Potentially, this technique can allow the observation of species with lifetimes of the order of 1 ms. To enhance the capabilities of this spectroscopic technique, we utilized it in combination with steady-state voltammetry at a microelectrode, to increase the concentration of unstable intermediates near the electrode surface. To determine the detection limit of this combined technique, we varied the base concentration as a means for varying the lifetime the radical cation electrogenerated from 9,10-dichloroanthracene. Well-resolved resonance Raman spectra were obtained for this radical cation when the lifetime was > or = 0.1 ms. This short time resolution achieved with micro-Raman spectroelectrochemistry makes this technique a powerful tool for the characterization of short-lived intermediates that are generated electrochemically in solution.     

Computerized service delivery in clinical psychology.

Compares the attributes of human clinicians and computer models as a means of examining their compatibility in service delivery. The use of the computer in psychophysiology and biofeedback, interviewing, assessment and diagnosis, and treatment is also reviewed. Economic and ethical considerations in the use of computers, as well as technological and professional obstacles to their adoption, are discussed. Psychologists and other mental health professionals are encouraged to take a more aggressive role in developing, testing, and adopting computerized service-delivery applications. Recommendations are made regarding the need for a detailed empirical analysis of attitudes and patterns of computer use in clinical psychology. (4 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)