Hydrogen Generation Catalyzed by Fluorinated Diglyoxime−Iron Complexes at Low Overpotentials

Fe^(II) complexes containing the fluorinated ligand 1,2-bis(perfluorophenyl)ethane-1,2-dionedioxime (dAr^FgH_2; H = dissociable proton) exhibit relatively positive Fe^(II/I) reduction potentials. The air-stable difluoroborated species [(dAr^FgBF_2)_2Fe(py)_2] (2) electrocatalyzes H_2 generation at −0.9 V vs SCE with i_(cat)/i_p ≈ 4, corresponding to a turnover frequency (TOF) of ~ 20 s^(–1) [Faradaic yield (FY) = 82 ± 13%]. The corresponding monofluoroborated, proton-bridged complex [(dArFg2H-BF2)Fe(py)2] (3) exhibits an improved TOF of ~ 200 s^(–1) (i_(cat)/i_p ≈ 8; FY = 68 ± 14%) at −0.8 V with an overpotential of 300 mV. Simulations of the electrocatalytic cyclic voltammograms of 2 suggest rate-limiting protonation of an Fe“0” intermediate (k_(RLS) ≈ 200 M^(–1) s^(–1)) that undergoes hydride protonation to form H_2. Complex 3 likely reacts via protonation of an Fe^I intermediate that subsequently forms H_2 via a bimetallic mechanism (k_(RLS) ≈ 2000 M^(–1) s^(–1)). 3 catalyzes production at relatively positive potentials compared with other iron complexes

Time evolution of the Partridge-Barton Model

The time evolution of the Partridge-Barton model in the presence of the pleiotropic constraint and deleterious somatic mutations is exactly solved for arbitrary fecundity in the context of a matricial formalism. Analytical expressions for the time dependence of the mean survival probabilities are derived. Using the fact that the asymptotic behavior for large time $t$ is controlled by the largest matrix eigenvalue, we obtain the steady state values for the mean survival probabilities and the Malthusian growth exponent. The mean age of the population exhibits a $t^{-1}$ power law decayment. Some Monte Carlo simulations were also performed and they corroborated our theoretical results.Comment: 10 pages, Latex, 1 postscript figure, published in Phys. Rev. E 61, 5664 (2000

Interpretation of x-ray-absorption dichroism experiments

A rule is derived to use x-ray magnetic circular dichroism spectra to extract the magnetic moment of the conduction-band states with j= l -1/2 separately from those with j= l + 1/2 as a function of energy. This quantity is straightforward to determine from the electronic band structure. The rule is illustrated with an application to pure iron and to the random substitutional alloy Fe_{80}CO_{20}

Evaluasi Penyediaan, Pengelolaan dan Daya Layan Fasilitas Tempat Penampungan Sampah Sementara di Kecamatan Andir Kota Bandung

Tahap pengumpulan sampah di tempat penampungan sampah sementara (TPS) menjadi salah satu aspek dalam pengelolaan persampahan yang membutuhkan perhatian khusus. Penelitian ini bertujuan untuk mengetahui persebaran fasilitas TPS di Kecamatan Andir, mengevaluasi aspek penyediaan, pengelolaan, dan daya layan fasilitas TPS, mengidentifikasi permasalahan di TPS, dan memberikan rekomendasi kebijakan dalam mengoptimalisasikan fungsi TPS yang ada di Kecamatan Andir, Kota Bandung.Penelitian ini menggunakan metode survey deskriptif dan teknik analisis pola spasial dengan pendekatan kualitatif. Hasil penelitian menunjukkan 9 TPS di Kecamatan Andir tersebar di 3 dari 6 kelurahan. Penyediaan beberapa TPS belum sesuai, proses pemilahan sampah di TPS dinilai belum optimal, dan terdapat 6 dari 9 TPS yang belum memenuhi daya layannya. Rekomendasi kebijakan diantaranya melalui penambahan jumlah TPS, pemenuhan standarisasi bangunan fisik TPS, pengoptimalisasian pemilahan sampah, penanganan sampah yang menumpuk di TPS 3R Pasar Ciroyom, penentuan area layan TPS secara spesifik, serta penambahan jumlah kendaraan pengangkut dari TPS ke TPA

The Effect of Private Schooling on Learning Outcomes in South Asia and East Africa: A Within-Family Approach

A contentious debate in academic as well as policy circles relates to the growth in private schooling in Sub-Saharan Africa and other low-income regions. While proponents highlight the superior learning outcomes of pupils in private schools, others have argued that this is merely a reflection of the more advantaged family background of private school pupils, rather than an effect of private schooling itself. We contribute to this debate by providing estimates derived from household fixed effect models, which control for any observed or unobserved differences between government and private school pupils at the household level. We argue that these can be interpreted as an upper bound estimate of the effect of private schooling on learning. We rely on large-scale, comparable household survey data from Kenya, Uganda, India and Pakistan, focusing on children enrolled in grade 2 to 6 of primary school. Private school attendance ranges from 12% in Kenya to 33% in rural India, with substantial within-household variation. Preliminary findings show that controlling for family background almost eliminates the positive effect of private schooling in rural Pakistan and reduces it by around half in rural India, Kenya and Uganda, to about a quarter of a standard deviation. Subgroup analyses show that the effect of private schooling does not differ substantially between high- and low-SES families. We discuss implications for educational policy

Vlasov simulation in multiple spatial dimensions

A long-standing challenge encountered in modeling plasma dynamics is achieving practical Vlasov equation simulation in multiple spatial dimensions over large length and time scales. While direct multi-dimension Vlasov simulation methods using adaptive mesh methods [J. W. Banks et al., Physics of Plasmas 18, no. 5 (2011): 052102; B. I. Cohen et al., November 10, 2010, http://meetings.aps.org/link/BAPS.2010.DPP.NP9.142] have recently shown promising results, in this paper we present an alternative, the Vlasov Multi Dimensional (VMD) model, that is specifically designed to take advantage of solution properties in regimes when plasma waves are confined to a narrow cone, as may be the case for stimulated Raman scatter in large optic f# laser beams. Perpendicular grid spacing large compared to a Debye length is then possible without instability, enabling an order 10 decrease in required computational resources compared to standard particle in cell (PIC) methods in 2D, with another reduction of that order in 3D. Further advantage compared to PIC methods accrues in regimes where particle noise is an issue. VMD and PIC results in a 2D model of localized Langmuir waves are in qualitative agreement

Measuring equity for national education planning

This chapter presents evidence on the extent to which different indicators included in national education plans take account of equity as discussed in Chapters 2 and 3. It is fairly common to find equity measures in plans for indicators related to access at the primary level. But few national education plans include indicators for learning and, for those that do so, the main dimension of inequality included is sex. Where plans do include measures of equity, these are most often associated with impartiality in that they track sub-groups of the population separately or assess parity between these sub-groups. This chapter highlights positive country examples for tracking progress to achieve equity in access and learning. It then highlights the importance of including a wider range of dimensions of disadvantage within education plans, discusses what data need to be collected and proposes methods to track progress to identify how inequalities have changed over time. The chapter aims in particular to advise policymakers on what information should be taken into account when deciding on the types of indicators that are suitable for tracking progress on learning