Hierarchiral 4-tetranitro copper(II)phthalocyanine based metal organic framework hybrid composite with improved electrocatalytic efficiency towards hydrogen evolution reaction

A novel hybrid-hybrid nanocomposite based on 4-tetranitro copper(II)phthalocyanine (TNCuPc) grown on metal organic frameworks (MOF) as a noble metal-free catalyst for hydrogen evolution reaction (HER) was developed by a simple impregnation method. The structure, surface area and the morphology of the bare MOF, TNCuPc and the TNCuPc/MOF composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, ultraviolet-visible spectroscopy, Brunauer-Emmet-Teller, scanning electron microscopy, transmission electron microscopy and simultaneous thermal analysis. The electrocatalytic activity of the samples towards the HER was evaluated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry, exchange current density, i0, Tafel slope value, b, as well as charge transfer coefficient, α. The spectroscopic analyses indicated a successful synthesis of TNCuPc and its composite. The morphological results showed the development of rod-like structures of TNCuPc on the surface of the MOF. The composite exhibited an onset potential of about −0.713 V vs. Ag/AgCl in 0.1 M TBAP/DMSO and 0.3 M H2SO4 solutions, which is 44 mV and 9 mV more positive than that of MOF and TNCuPc respectively. The composite showed the rate determining step (RDS) to be the Volmer reaction in conjunction with either Heyrovsky or Tafel reaction as the RDS due to the Tafel slope value of 147 mV/dec and an α of 0.4. The i0 value of the TNCuPc/MOF composite was about 1.6 times that of the bare MOF. The EIS results showed the charge transfer resistance (Rct) of 12.6 kΩ for the TNCuPc/MOF composite as compared to MOF and TNCuPc values of 41 and 18.6 kΩ, respectively, demonstrating an excellent conductivity of the composite. In addition, Rct values of materials follow the sequence, blank < MOF < TNCuPc < TNCuPc/MOF. The fabricated composite displayed high activity towards the HER, high thermal stability, and excellent tolerance. Therefore, TNCuPc/MOF non-noble electrocatalyst can be a promising electrochemical catalyst to replace Pt-based catalysts for electrochemical hydrogen production

Dosage, intensity, and frequency of language therapy for Aphasia: A systematic review-based, individual participant data network meta-analysis

Background and Purpose: Optimizing speech and language therapy (SLT) regimens for maximal aphasia recovery is a clinical research priority. We examined associations between SLT intensity (hours/week), dosage (total hours), frequency (days/week), duration (weeks), delivery (face to face, computer supported, individual tailoring, and home practice), content, and language outcomes for people with aphasia. Methods: Databases including MEDLINE and Embase were searched (inception to September 2015). Published, unpublished, and emerging trials including SLT and ≥ 10 individual participant data on aphasia, language outcomes, and time post-onset were selected. Patient-level data on stroke, language, SLT, and trial risk of bias were independently extracted. Outcome measurement scores were standardized. A statistical inferencing, one-stage, random effects, network meta-analysis approach filtered individual participant data into an optimal model examining SLT regimen for overall language, auditory comprehension, naming, and functional communication pre-post intervention gains, adjusting for a priori–defined covariates (age, sex, time poststroke, and baseline aphasia severity), reporting estimates of mean change scores (95% CI). Results: Data from 959 individual participant data (25 trials) were included. Greatest gains in overall language and comprehension were associated with \u3e 20 to 50 hours SLT dosage (18.37 [10.58–26.16] Western Aphasia Battery–Aphasia Quotient; 5.23 [1.51–8.95] Aachen Aphasia Test–Token Test). Greatest clinical overall language, functional communication, and comprehension gains were associated with 2 to 4 and 9+ SLT hours/week. Greatest clinical gains were associated with frequent SLT for overall language, functional communication (3–5+ days/week), and comprehension (4–5 days/week). Evidence of comprehension gains was absent for SLT ≤ 20 hours, \u3c 3 hours/week, and ≤ 3 days/week. Mixed receptive-expressive therapy, functionally tailored, with prescribed home practice was associated with the greatest overall gains. Relative variance was \u3c 30%. Risk of trial bias was low to moderate; low for meta-biases. Conclusions: Greatest language recovery was associated with frequent, functionally tailored, receptive-expressive SLT, with prescribed home practice at a greater intensity and duration than reports of usual clinical services internationally. These exploratory findings suggest critical therapeutic ranges, informing hypothesis-testing trials and tailoring of clinical services

PCA model building with missing data: New proposals and a comparative study

[EN] This paper introduces new methods for building principal component analysis (PCA) models with missing data: projection to the model plane (PMP), known data regression (KDR), KDR with principal component regression (PCR), KDR with partial least squares regression (PLS) and trimmed scores regression (TSR). These methods are adapted from their PCA model exploitation version to deal with the more general problem of PCA model building when the training set has missing values. A comparative study is carried out comparing these new methods with the standard ones, such as the modified nonlinear iterative partial least squares (NIPALS), the it- erative algorithm (IA), the data augmentation method (DA) and the nonlinear programming approach (NLP). The performance is assessed using the mean squared prediction error of the reconstructed matrix and the cosines between the actual principal components and the ones extracted by each method. Four data sets, two simulated and two real ones, with several percentages of missing data, are used to perform the comparison. Guardar / Salir Siguiente >Research in this study was partially supported by the Spanish Ministry of Science and Innovation and FEDER funds from the European Union through grant DPI2011-28112-C04-02, and the Spanish Ministry of Economy and Competitiveness through grant ECO2013-43353-R. The authors gratefully acknowledge Salvador Garcia-Munoz for providing the Phi toolbox (version 1.7) to perform the nonlinear programming approach (NLP) method.Folch-Fortuny, A.; Arteaga Moreno, FJ.; Ferrer Riquelme, AJ. (2015). PCA model building with missing data: New proposals and a comparative study. Chemometrics and Intelligent Laboratory Systems. 146:77-88. https://doi.org/10.1016/j.chemolab.2015.05.006S778814

Agent-based simulation of open source evolution

We present an agent-based simulation model developed to study how size, complexity and effort relate to each other in the development of open source software (OSS). In the model, many developer agents generate, extend, and re-factor code modules independently and in parallel. This accords with empirical observations of OSS development. To our knowledge, this is the first model of OSS evolution that includes the complexity of software modules as a limiting factor in productivity, the fitness of the software to its requirements, and the motivation of developers. Validation of the model was done by comparing the simulated results against four measures of software evolution (system size, proportion of highly complex modules, level of complexity control work, and distribution of changes) for four large OSS systems. The simulated results resembled the observed data, except for system size: three of the OSS systems showed alternating patterns of super-linear and sub-linear growth, while the simulations produced only super-linear growth. However, the fidelity of the model for the other measures suggests that developer motivation and the limiting effect of complexity on productivity have a significant effect on the development of OSS systems and should be considered in any model of OSS development