Preparation and optimization of TiO2 photoanodes fabricated by pulsed laser deposition for photoelectrochemical water splitting

Quasi-1D TiO2 nanostructures prepared by pulsed laser deposition (PLD) are tested as photoanodes for photoelectrochemical water splitting application and compared with TiO2 nanotube arrays prepared by anodic oxidation. PLD TiO2 films with controlled structure and morphology ranging from compact to vertically oriented or hierarchical porous nanostructures are deposited by ablating a TiO2 target with nanosecond UV laser pulses in the presence of an O2 background atmosphere at different pressures. Thermal treatments at different temperatures are used to transform the so-obtained amorphous systems into nanocrystalline structures (mainly anatase). The effect of film density and thickness is also considered by depositing different amounts of material per unit surface. The morphology and the phase composition of the samples are characterized by SEM and Raman spectroscopy, while the photoelectrochemical water splitting performances are investigated by monitoring the photocurrent generated under illumination in a three-electrode cell. Voltammetric scans and electrochemical impedance spectroscopy analysis were also used to correlate the morphology of PLD samples with their electrochemical properties and their working mechanism in the absence and presence of a light radiation. A clear correlation between structural/morphological properties and photoelectrochemical behavior is found and ideal values of the synthesis parameters are identified, which allow the identification of the optimal quasi-1D nanoporous morphology for water splitting applications. The use of sacrificial organic reagents as hole scavengers was also considered to improve the photoelectrochemical performance of the samples

Iatrogenic nerve injury in primary and revision reverse total shoulder arthroplasty

INTRODUCTION Iatrogenic nerve injury in orthopedic surgery can impair functional outcomes. During the last years, a steady increase in the number of performed reverse total shoulder arthroplasties has been reported and complications associated with this procedure are continuously described. Neurological complications, however, remain underreported. The aims of this study were to calculate the incidence of iatrogenic nerve injury after primary and revision reverse total shoulder arthroplasty in a large patient cohort, as well as identify associated patient-and surgery-related risk factors. MATERIALS AND METHODS A retrospective review of our institution's internal Reverse Total Shoulder Arthroplasty (RTSA) database from September 2005 to December 2019 was undertaken and 34 patients with iatrogenic nerve injuries were identified, resulting in a neurological complication rate of 2.6%. Group comparisons between patients with nerve injuries (n = 34) and the remaining cohort without nerve injuries (n = 1275) were performed to identify patient- and surgery-related risk factors. RESULTS Of the 34 cases with iatrogenic nerve injury, damage to terminal nerve branches occurred in 21 patients, whereas a brachial plexus lesion was diagnosed in the other 13. Nerve revision surgery was necessary in four patients. At final follow-up 13 patients (45%) had residual motor deficits and 17 (59%) had residual sensory deficits. Higher numbers of previous surgeries of the affected shoulder correlated with subsequent nerve injury (p = 0.035). Operative time was significantly longer in patients, who developed a neurologic deficit, showing a correlation between duration of surgery and occurrence of nerve injury (p = 0.013). Patients with neurologic complications were significantly younger than patients without nerve damage (median 68 vs. 72 years, p = 0.017). CONCLUSIONS In specialists' hands reverse total shoulder arthroplasty is a rather safe procedure regarding the risk of neurologic injury. However, multiple previous surgeries of the affected shoulder increase the risk of neurological complications. Cases with post-operative neurologic compromise are rare and usually recover well, with few patients suffering long-term functional deficits from iatrogenic nerve injury. LEVEL OF EVIDENCE Level III, retrospective cohort study

Non-steady 3D dendrite tip growth under diffusive and weakly convective conditions

Three dimensional α-Al dendrite tip growth under varying solute gradients in an Al-Cu-Si alloy melt has been studied using real time synchrotron X-ray imaging and mathematical modelling. X-radiographic image sequences with high temporal and spatial resolution were processed and analysed to retrieve three-dimensional spatial details of the evolving dendrite and the solute concentration field, providing vastly improved estimates for the latter, in particular for the melt regions adjacent to the dendrite tips. Computational results obtained from an extended Horvay-Cahn dendrite tip model, capable of taking into account the effects of sample confinement, showed good agreement with the experimental data, and can be taken to verify the robustness of the 3D data extraction protocol.European Commission - Seventh Framework Programme (FP7)Engineering and Physical Sciences Research Council (EPSRC) UKNorwegian Research Council, SYNKNOYT programm

User defined nodal displacement of numerical mesh for analysis of screw machines in FLUENT

Growing demands to reduce energy consumption are driving researchers towards in-depth analysis of positive displacement machines. Twin screw compressors are amongst the most common types of positive displacement machines. These machines have inherently complex geometry due to intricate rotor profiles used. As the details of the internal flows are difficult to obtain experimentally, Computational Fluid Dynamics (CFD) offers a good alternative for evaluation of internal flow patterns. However, implementation of CFD is challenging due complex deforming geometries. In this paper, a customised grid generator SCORGTM developed by authors is used to generate numerical meshes for commercially available solver ANSYS FLUENT. FLUENT is an unstructured solver which offers flexibility of using both segregated and coupled solution algorithms. Segregated algorithms are generally faster which results in shorter product development time. Interface with FLUENT is implemented by performing User Defined Nodal Displacements (UDND) of grids generated by SCORG in a parallel framework. For this purpose, SCORG and UDND are coupled and extended to work with FLUENT's parallel architecture. The developed code is compiled within the solver. The oil free air screw compressor with 'N' profile rotors and 3/5 lobe combination is modelled for 8000 RPM and 6000 RPM. Finally, the predicted performance values with FLUENT are compared to previously calculated CFX predictions and experimental results. FLUENT requires shorter solution time to obtain same accuracy of CFX

Maternal characteristics during pregnancy and risk factors for positive HIV RNA at delivery: a single-cohort observational study (Brescia, Northern Italy)

<p>Abstract</p> <p>Background</p> <p>Detectable HIV RNA in mothers at delivery is an important risk factor for HIV transmission to newborns. Our hypothesis was that, in migrant women, the risk of detectable HIV RNA at delivery is greater owing to late HIV diagnosis. Therefore, we examined pregnant women by regional provenance and measured variables that could be associated with detectable HIV RNA at delivery.</p> <p>Methods</p> <p>A observational retrospective study was conducted from January 1999 to May 2008. Univariate and multivariable regression analyses (generalized linear models) were used, with detectable HIV RNA at delivery as dependent variable.</p> <p>Results</p> <p>The overall population comprised 154 women (46.8% migrants). Presentation was later in migrant women than Italians, as assessed by CD4-T-cell count at first contact (mean 417/mm³versus 545/mm³, respectively; p = 0.003). Likewise, HIV diagnosis was made before pregnancy and HAART was already prescribed at the time of pregnancy in more Italians (91% and 75%, respectively) than migrants (61% and 42.8%, respectively). A subgroup of women with available HIV RNA close to term (i.e., ≤30 days before labour) was studied for risk factors of detectable HIV RNA (≥50 copies/ml) at delivery. Among 93 women, 25 (26.9%) had detectable HIV RNA. A trend toward an association between non-Italian nationality and detectable HIV RNA at delivery was demonstrated by univariate analysis (relative risk, RR = 1.86; p = 0.099). However, by multivariable regression analysis, the following factors appeared to be more important: lack of stable (i.e., ≥14 days) antiretroviral therapy at the time of HIV RNA testing (RR = 4.3; p < 0.0001), and higher CD4+ T-cell count at pregnancy (per 50/mm³, RR = 0.94; p = 0.038).</p> <p>Conclusions</p> <p>These results reinforce the importance of extensive screening for HIV infection, earlier initiation of antiretroviral therapy and stricter monitoring of pregnant women to reduce the risk of detectable HIV RNA at delivery. Public health interventions should be particularly targeted to migrant women who are frequently unaware of their HIV status at the time of pregnancy.</p

Regulation of OPA1 processing and mitochondrial fusion by m-AAA protease isoenzymes and OMA1

m-AAA proteases cleave OPA1 to ensure a balance of long and short OPA1 isoforms, whereas cleavage by OMA1 causes an accumulation of the short OPA1 variants. (See also companion paper from Head et al. in this issue.