Gallium indium phosphide microstructures with suppressed photoluminescence for applications in nonlinear optics.

Gallium indium phosphide (Ga0.51In0.49P), lattice matched to gallium arsenide, shows remarkable second-order nonlinear properties, as well as strong photoluminescence (PL) due to its direct band gap. By measuring the second-harmonic generation from the GaInP microwaveguide (0.2×11×1300 µm) before and after stimulating intrinsic photobleaching, we demonstrate that the PL could be strongly suppressed (-34 dB), leaving the nonlinear properties unchanged, making it suitable for low-noise applications.

Recessive ITPA mutations cause an early infantile encephalopathy.

OBJECTIVE: To identify the etiology of a novel, heritable encephalopathy in a small group of patients. METHODS: Magnetic resonance imaging (MRI) pattern analysis was used to select patients with the same pattern. Homozygosity mapping and whole exome sequencing (WES) were performed to find the causal gene mutations. RESULTS: Seven patients from 4 families (2 consanguineous) were identified with a similar MRI pattern characterized by T2 signal abnormalities and diffusion restriction in the posterior limb of the internal capsule, often also optic radiation, brainstem tracts, and cerebellar white matter, in combination with delayed myelination and progressive brain atrophy. Patients presented with early infantile onset encephalopathy characterized by progressive microcephaly, seizures, variable cardiac defects, and early death. Metabolic testing was unrevealing. Single nucleotide polymorphism array revealed 1 overlapping homozygous region on chromosome 20 in the consanguineous families. In all patients, WES subsequently revealed recessive predicted loss of function mutations in ITPA, encoding inosine triphosphate pyrophosphatase (ITPase). ITPase activity in patients' erythrocytes and fibroblasts was severely reduced. INTERPRETATION: Until now ITPA variants have only been associated with adverse reactions to specific drugs. This is the first report associating ITPA mutations with a human disorder. ITPase is important in purine metabolism because it removes noncanonical nucleotides from the cellular nucleotide pool. Toxicity of accumulated noncanonical nucleotides, leading to neuronal apoptosis and interference with proteins normally using adenosine triphosphate/guanosine triphosphate, probably explains the disease. This study confirms that combining MRI pattern recognition to define small, homogeneous patient groups with WES is a powerful approach for providing a fast diagnosis in patients with an unclassified genetic encephalopathy.

Effectiveness and characteristics of physical fitness training on aerobic fitness in vulnerable older adults: an umbrella review of systematic reviews.

OBJECTIVES: To present an overview of effectiveness and training characteristics of physical training on aerobic fitness, compared with alternative or no training, in adults aged over 65 years with various health statuses, providing a basis for guidelines for aerobic training of vulnerable older adults that can be used in geriatric rehabilitation. DESIGN: An umbrella review of systematic reviews that included both randomised controlled trials and other types of trials. DATA SOURCES: MEDLINE, Embase, CINAHL and the Cochrane Library were searched on 9 September 2019. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: We included systematic reviews reporting on physical training interventions that are expected to improve aerobic fitness, presenting results for adults aged 65 years and older, describing at least one of the FITT-characteristics: Frequency, Intensity, Time or Type of exercise, and measuring aerobic fitness at least before and after the intervention. DATA EXTRACTION AND SYNTHESIS: Two independent reviewers extracted the data and assessed the risk of bias. A narrative synthesis was performed. RESULTS: We included 51 papers on 49 reviews. Positive effect of training on aerobic fitness was reported by 33 reviews, 11 reviews remained inconclusive and 5 reviews reported no effect. Training characteristics varied largely. Frequency: 1-35 sessions/week, Intensity: light-vigorous, Time: <10-120 min/session and Types of exercise: many. The methodological quality was most often low. Subgroup analyses revealed positive effects for all health conditions except for trauma patients. Exercise characteristics from current existing guidelines are widely applicable. For vulnerable older adults, lower intensities and lower frequencies were beneficial. Some health conditions require specific adjustments. Information on adverse events was often lacking, but their occurrence seemed rare. CONCLUSION: Physical fitness training can be effective for vulnerable older adults. Exercise characteristics from current existing guidelines are widely applicable, although lower frequencies and intensities are also beneficial. For some conditions, adjustments are advised. PROSPERO REGISTRATION NUMBER: CRD42020140575.

Psychometrics of the observational scales of the Utrecht Scale for Evaluation of Rehabilitation (USER): Content and structural validity, internal consistency and reliability.

INTRODUCTION: Establish content and structural validity, internal consistency, inter-rater reliability, and measurement error of the physical and cognitive scales of the Utrecht Scale for Evaluation clinical Rehabilitation (USER) in geriatric rehabilitation. MATERIAL AND METHODS: First, an expert consensus-meeting (N=7) was organised for content validity wherein scale content validity index (CVI) was measured. Second, in a sample of geriatric rehabilitation patient structural validity (N=616) was assessed by confirmatory factor analyses for exploring unidimensionality. Cut-off criteria were: Root Mean Square Error of Approximation (RMSEA) ≤0.08; Comparative Fit Index (CFI) and Tucker Lewis Index (TLI) ≥0.95. Local independence (residual correlation<0.20) and monotonicity (Hi-coefficient ≥0.30 and Hs-coefficient ≥0.50) were also calculated. Cronbach alphas were calculated for internal consistency. Alpha's > 0.7 was considered adequate. Third, two nurses independently administered the USER to 37 patients. Intraclass-correlation coefficients (ICC) were calculated for inter-rater reliability (IRR), standard error of measurement (SEM) and Smallest Detectable Change (SDC). RESULTS: The CVI for physical functioning was moderate (0.73) and excellent for cognitive functioning (0.97). Structural validity physical scale was acceptable (CFI;0.95, TLI;0.93, RMSEA;0.07, ECV;0.78, OmegaH;0.87; Monotonicity;(Hi;0.52-0.75 and Hs;0.63)). Cognitive scale was good (CFI;0.98, TLI;0.96, RMSEA;0.05, ECV;0.66 and OmegaH;0.90. Monotonicity;(Hi;0.30 -0.70 and Hs;0.61)). Cronbach's alpha were high: physical scale;0.92 and cognitive scale;0.94. Reliability physical scale ICC;0.94, SEM;5 and SDC;14 and cognitive scale ICC;0.88, SEM;5 and SDC;13. CONCLUSION: The observational scales of the USER have shown sufficient content and structural validity, internal consistency, and interrater reliability for measuring physical and cognitive function in geriatric rehabilitation. TRIAL REGISTRATION: N/A.

GaInP nanowire arrays for color conversion applications.

Color conversion by (tapered) nanowire arrays fabricated in GaInP with bandgap emission in the red spectral region are investigated with blue and green source light LEDs in perspective. GaInP nano- and microstructures, fabricated using top-down pattern transfer methods, are derived from epitaxial Ga0.51In0.49P/GaAs stacks with pre-determined layer thicknesses. Substrate-free GaInP micro- and nanostructures obtained by selectively etching the GaAs sacrificial layers are then embedded in a transparent film to generate stand-alone color converting films for spectrophotometry and photoluminescence experiments. Finite-difference time-domain simulations and spectrophotometry measurements are used to design and validate the GaInP structures embedded in (stand-alone) transparent films for maximum light absorption and color conversion from blue (450 nm) and green (532 nm) to red (~ 660 nm) light, respectively. It is shown that (embedded) 1 µm-high GaInP nanowire arrays can be designed to absorb ~ 100% of 450 nm and 532 nm wavelength incident light. Room-temperature photoluminescence measurements with 405 nm and 532 nm laser excitation are used for proof-of-principle demonstration of color conversion from the embedded GaInP structures. The (tapered) GaInP nanowire arrays, despite very low fill factors (~ 24%), can out-perform the micro-arrays and bulk-like slabs due to a better in- and out-coupling of source and emitted light, respectively.

Embossed Mie resonator arrays composed of compacted TiO2 nanoparticles for broadband anti-reflection in solar cells.

Mie resonator arrays formed by embossing titanium dioxide (TiO2) nanoparticles (NPs) from solution are investigated as optical coatings for anti-reflection applications. Compacted nanoparticle assemblies offer unique possibilities to tailor the effective refractive index (RI). Here, we demonstrate a simple table-top, low pressure, and low temperature method to fabricate structured optical coatings. TiO2 nanostructures in the form of nanodisks support Mie resonances in the visible wavelength spectrum and exhibit strong forward scattering into the high index substrates, making them suitable as broadband anti-reflection coatings for solar cells. TiO2 NP-based nanodisk arrays are designed, fabricated, and characterized regarding their anti-reflection properties on Si, GaAs, and InP substrates and solar cells. Detailed finite-difference time-domain simulations are performed to optimize the TiO2 NP-based Mie resonator arrays for the broadband anti-reflection as well as to explain the measured reflectance spectra. The solar-weighted reflectance is used as a figure of merit (FoM). TiO2 nanodisk arrays on Si show a FoM of ~ 7% in the 400-1,100 nm wavelength spectrum; similar values are obtained for GaAs and InP substrates. TiO2 nanodisk arrays embossed directly on prefabricated planar single-junction Si, GaAs, and InP solar cells result in an appreciable increase (~ 1.3 times) in the short-circuit current densities.

Room-temperature polarized spin-photon interface based on a semiconductor nanodisk-in-nanopillar structure driven by few defects.

Owing to their superior optical properties, semiconductor nanopillars/nanowires in one-dimensional (1D) geometry are building blocks for nano-photonics. They also hold potential for efficient polarized spin-light conversion in future spin nano-photonics. Unfortunately, spin generation in 1D systems so far remains inefficient at room temperature. Here we propose an approach that can significantly enhance the radiative efficiency of the electrons with the desired spin while suppressing that with the unwanted spin, which simultaneously ensures strong spin and light polarization. We demonstrate high optical polarization of 20%, inferring high electron spin polarization up to 60% at room temperature in a 1D system based on a GaNAs nanodisk-in-GaAs nanopillar structure, facilitated by spin-dependent recombination via merely 2-3 defects in each nanodisk. Our approach points to a promising direction for realization of an interface for efficient spin-photon quantum information transfer at room temperature-a key element for future spin-photonic applications.

Long-term clinical results of the Metasul metal-on-metal total hip arthroplasty: 12.6 years follow-up of 128 primary total hip replacements.

INTRODUCTION: The purpose of the present study is to report the long-term clinical results of an uncemented total hip arthroplasty (THA) using a Metasul metal-on-metal (MoM) 28-mm bearing and to evaluate the long-term serum cobalt levels. METHODS: At an average of 12.6 years following primary THA, we retrospectively reviewed the clinical results of the first 116 consecutive patients (128 THAs) in our institution who underwent 28-mm Metasul MoM THA. Of the 78 patients who were able to visit our outpatient clinic, serum cobalt levels were evaluated. RESULTS: The overall survival rate of the cohort was 96.1% (95% confidence interval [CI], 93.2-99.6), 12.6 years (95% CI, 12.3-12.7 years) following surgery. 3 patients had undergone revision due to aseptic loosening of the stem and 2 patients sustained a periprosthetic fracture. The average modified Harris Hip Score was 90 (72-97) and the average Oxford Hip Score was 56 (48-60), representing both excellent outcome scores. The average serum cobalt of the entire cohort was 20.1 nmol/L (range 8.5-227.7 nmol/L). Serum cobalt levels of patients with a bilateral MoM THA were significantly higher (35.0 nmol/l, p<0.01). No relation between serum cobalt levels, subjective outcome, radiolucent lines on radiographs and survivorship of the implant was noted. CONCLUSIONS: Long-term results of the metasul MoM bearing articulation in THA seem to be excellent, although cobalt serum levels should be monitored closely.

An HPLC-based assay of adenylosuccinate lyase in erythrocytes.

ADSL deficiency is a disorder of purine metabolism with a broad clinical spectrum. A rapid and simple HPLC-based assay to measure ADSL activity in erythrocytes was developed. The suitability of DBSs was assessed. ADSL activity was measured in erythrocyte lysates and DBS using succinyl-AMP as the substrate. Detection and quantification were performed using isocratic ion-pairing reversed-phase HPLC with UV-detection. Reference values in erythrocyte lysates were established. The intra- and interassay variations were 2% and 8%, respectively. ADSL deficiency was easily recognized. ADSL activity in DBS was highly unstable, disqualifying DBS for diagnostic procedures.

Simplified automated image analysis for detection and phenotyping of Mycobacterium tuberculosis on porous supports by monitoring growing microcolonies.

BACKGROUND: Even with the advent of nucleic acid (NA) amplification technologies the culture of mycobacteria for diagnostic and other applications remains of critical importance. Notably microscopic observed drug susceptibility testing (MODS), as opposed to traditional culture on solid media or automated liquid culture, has shown potential to both speed up and increase the provision of mycobacterial culture in high burden settings. METHODS: Here we explore the growth of Mycobacterial tuberculosis microcolonies, imaged by automated digital microscopy, cultured on a porous aluminium oxide (PAO) supports. Repeated imaging during colony growth greatly simplifies "computer vision" and presumptive identification of microcolonies was achieved here using existing publically available algorithms. Our system thus allows the growth of individual microcolonies to be monitored and critically, also to change the media during the growth phase without disrupting the microcolonies. Transfer of identified microcolonies onto selective media allowed us, within 1-2 bacterial generations, to rapidly detect the drug susceptibility of individual microcolonies, eliminating the need for time consuming subculturing or the inoculation of multiple parallel cultures. SIGNIFICANCE: Monitoring the phenotype of individual microcolonies as they grow has immense potential for research, screening, and ultimately M. tuberculosis diagnostic applications. The method described is particularly appealing with respect to speed and automation.