Categorical Diagnostic Analysis of “Slow Learners”

Slow learner: “It is a student with the ability to acquire all necessary academic skills, at a rate and depth below that of the average student”. Currently, there are many ways to diagnose the kind of students that teachers have in class. But there is also lack of experience in identifying slow learners, and sometimes they are considered as disable learners. This article tries to explain the concept about  diagnostic analysis, and also how to differentiate it from a disability. Taking into consideration that learning began in the preschool years, the period where the children assimilate the fundamental issues of the scientific knowledge, abilities and values; the researchers can give examples of how to take care of this kind of student, through the observation among others and from their own experience in teaching and growing up children. To support and confirm the validity of this work the document analysis of updated scientific literature related to this topic was developed. Finally, to corroborate its notion, experts’ opinions were taken into consideration.“Being a slow learner is a lifelong problem. A Slow Learner is a child whose IQ is low enough to cause considerable difficulty in keeping up in the classroom. An average IQ is 100%. Slow learners score between 70% and 90% on IQ tests. Less than 70% is considered Mentally Retarded. Slow Learners are not Mentally Retarded” This article tries to give an analysis of the slow learners’ concept, since the point of view that they are normal students. The differences can be managed among the diversity of each group. It also deals with the teacher responsibility on preparing themselves to provide a good teaching learning process in and out the classroom, that not only the teachers are involved in this process, also parents have the commitment on educating their children. We also give a wide connotation to the diagnosis and the different characteristics and needs of the slow learners. Finally, they include some example of exercises that can be developed in the classroom with standards or average and slow students; the fact is on the way the teacher manage each activity in order to help the slow learners without discriminating them Keywords: slow learners, normal students, standard students DOI: 10.7176/JEP/10-14-13 Publication date:May 31st 201

APPLICATION OF MARKOV CHAIN MODEL IN CAREER PROGRESSION OF UNIVERSITY ACADEMIC STAFF: A Case Study of the Moi University-Eldoret, Kenya.

The use of Mathematical models for manpower planning has increased in recent times for better manpower planning quantitatively both in public and private sectors. In respect of organizational management, numerous previous studies have applied Markov chain models in describing title or level promotions, demotions, recruitment, withdrawals, or changes of different career development paths to confirm the actual manpower needs of an organization or predict the future manpower needs. The movements of staff within the grades or job group levels called transitions are usually the consequences of promotions or transfers between segments or wastage and recruitment into the system. In this study we determined and compared the transition rates of the academic staff of science and art faculties, the expected time taken before one attains the highest academic rank, and the absorption rates in the university. The data was collected from Moi University- Eldoret and the grades or job groups were: Tutorial Fellow, Lecturer, Senior Lecturer, Associate Professor, and full Professor. The study established that the transition rates are high at the Tutorial fellow and lecturer levels in both science and art with 67.09% and 86.31% and 86.00% and 97.53% respectively within the first ten years of employment. But it was low at 50% at senior lecturer and associate professor in the faculty of science and 63.51% and 88.69% for the same ranks in the faculty of arts. . It took academic staff 19.51 years and 22.74 years in science and art respectively to attain the rank full professor. Keywords: Jobgroups, transitional rate, markov chain,absorption rate,expectatio

Characterization of the earliest intermediate of Fe-N_2 protonation: CW and Pulse EPR detection of an Fe-NNH species and its evolution to Fe-NNH_2^+

Iron diazenido species (Fe(NNH)) have been proposed as the earliest intermediates of catalytic N_2-to-NH_3 conversion (N_2RR) mediated by synthetic iron complexes and relatedly as intermediates of N_2RR by nitrogenase enzymes. However, direct identification of such iron species, either during or independent of catalysis, has proven challenging owing to their high degree of instability. The isolation of more stable silylated diazenido analogues, Fe(NNSiR_3), and also of further downstream intermediates (e.g., Fe(NNH_2)), nonetheless points to Fe(NNH) as the key first intermediate of protonation in synthetic systems. Herein we show that low-temperature protonation of a terminally bound Fe-N_2– species, supported by a bulky trisphosphinoborane ligand (^(Ar)P_3^B), generates an S = 1/2 terminal Fe(NNH) species that can be detected and characterized by continuous-wave (CW) and pulse EPR techniques. The ^1H-hyperfine for ^(Ar)P_3^BFe(NNH) derived from the presented ENDOR studies is diagnostic for the distally bound H atom (a_(iso) = 16.5 MHz). The Fe(NNH) species evolves further to cationic [Fe(NNH_2)]+ in the presence of additional acid, the latter being related to a previously characterized [Fe(NNH_2)]+ intermediate of N2RR mediated by a far less encumbered iron tris(phosphine)borane catalyst. While catalysis is suppressed in the present sterically very crowded system, N_2-to-NH_3 conversion can nevertheless be demonstrated. These observations in sum add support to the idea that Fe(NNH) plays a central role as the earliest intermediate of Fe-mediated N2RR in a synthetic system

S = 3 Ground State for a Tetranuclear Mn^(IV)₄O₄ Complex Mimicking the S₃ State of the Oxygen Evolving Complex

The S₃ state is currently the last observable intermediate prior to O–O bond formation at the oxygen-evolving complex (OEC) of Photosystem II, and its electronic structure has been assigned to a homovalent Mn^(IV)₄ core with an S = 3 ground state. While structural interpretations based on the EPR spectroscopic features of the S₃ state provide valuable mechanistic insight, corresponding synthetic and spectroscopic studies on tetranuclear complexes mirroring the Mn oxidation states of the S₃ state remain rare. Herein, we report the synthesis and characterization by XAS and multifrequency EPR spectroscopy of a Mn^(IV)₄O₄ cuboidal complex as a spectroscopic model of the S₃ state. Results show that this Mn^(IV)₄O₄ complex has an S = 3 ground state with isotropic ⁵⁵Mn hyperfine coupling constants of −75, −88, −91, and 66 MHz. These parameters are consistent with an αααβ spin topology approaching the trimer–monomer magnetic coupling model of pseudo-octahedral Mn^(IV) centers. Importantly, the spin ground state changes from S = 1/2 to S = 3 as the OEC is oxidized from the S₂ state to the S₃ state. This same spin state change is observed following oxidation of the previously reported Mn^(III)Mn^(IV)₃O₄ cuboidal complex to the Mn^(IV)₄O₄ complex described here. This sets a synthetic precedent for the observed low-spin to high-spin conversion in the OEC

Final Report on Humidification-Dehumidification Desalination Prototype

Freshwater available across the globe is decreasing daily due to population growth, climate change, and pollution. The growing scarcity of freshwater affects more than a billion people worldwide and has prompted increased research into desalination processes. Large desalination plants are already in operation but are very expensive to build. Not every community has the means to implement these large systems, advancing the need for smaller, more economical, and efficient desalination plants. The Desalinators researched and designed a humidification-dehumidification (HDH) desalination prototype that will convert saline water into potable water at a household scale (approximately 5-10 gal/day of freshwater). The sponsor, SwRI, intends to use the results of this project to further their research into the applications and improvements of small-scale HDH processes. Therefore, the prototype need not be perfect as long as it produces results that can be measured and analyzed. The prototype features four main subsystems: primary heater, air circulation system, humidifier, and condenser. After the team’s extensive research, the final prototype was built using a water heater provided by the sponsor, an air pump (for forced convection) provided by the University, a packed bed tower humidifier with Raschig rings, and an ice bath within a plastic bucket with an air separator for the condenser. A schematic of the final prototype can be found in the figure section of the appendix. The team chose these components to maximize the performance of the prototype while minimizing costs. The six project requirements included the following: the prototype shall use the HDH process to desalinate saline water into potable water; the prototype should operate within ±20% error of design parameters, including operating temperature, humidity at inlet and outlet, and outlet salt content; the prototype shall allow the operating temperature, humidity at inlet and outlet, and outlet salt content to be measured; the prototype should allow efficiency to be measured and compared to current desalination processes via gained-output ratio (GOR), recovery ratio (RR), or other efficiency measures; the prototype should allow outlet water samples to be collected and tested by instruments provided by SwRI; and the prototype may produce between 5-10 gallons/day. To meet these requirements, several “complete prototype tests” were conducted in which temperatures, flow rates, humidity, and salinities were measured at 3-minute intervals during a 21-30 minute test. The complete prototype tests were conducted at a variety of water heater setpoints and flow rates. An additional “long test” was conducted as well where the same values were measured but for 100 minutes at 4-minute intervals. Using the results of these tests, the team was able to show that the prototype successfully met all but the last project requirement regarding potable water output volume and selecting optimal operating conditions. The potable water volume production rate could be increased if the tubing used within the prototype was upgraded to better withstand moderate pressures as well as using larger water and air pumps to increase flow rates

Hydrazine Formation via Coupling of a Ni^(III)-NH₂ Radical

M(NH_x) intermediates involved in N–N bond formation are central to ammonia oxidation (AO) catalysis, an enabling technology to ultimately exploit ammonia (NH₃) as an alternative fuel source. While homocoupling of a terminal amide species (M–NH₂) to form hydrazine (N₂H₄) has been proposed, well‐defined examples are without precedent. Herein, we discuss the generation and electronic structure of a Ni^(III)–NH₂ species that undergoes bimolecular coupling to generate a Ni^(II)₂(N₂H₄) complex. This hydrazine adduct can be further oxidized to a structurally unusual Ni₂(N₂H₂) species; the latter releases N₂ in the presence of NH₃, thus establishing a synthetic cycle for Ni‐mediated AO. Distribution of the redox load for H₂N–NH₂ formation via NH₂ coupling between two metal centers presents an attractive strategy for AO catalysis using Earth‐abundant, late first‐row metals

Terminal Molybdenum Phosphides with d Electrons: Radical Character Promotes Coupling Chemistry

A terminal Mo phosphide was prepared via group transfer of both P- and Cl-atoms from chloro-substituted dibenzo-7λ^3-phosphanorbornadiene. This compound represents the first structurally characterized terminal transition metal phosphide with valence d electrons. In the tetragonal ligand field, these electrons populate an orbital of d_(xy) parentage, an electronic configuration that accommodates both metal d-electrons and a formal M≡P triple bond. Single electron oxidation affords a transient open shell terminal phosphide cation with significant spin density on P, as corroborated by CW and pulsed EPR characterization. Facile P-P bond formation occurs from this species via intermolecular phosphide coupling

H₂ Evolution from a Thiolate-Bound Ni(III) Hydride

Terminal Ni^(III) hydrides are proposed intermediates in proton reduction catalyzed by both molecular electrocatalysts and metalloenzymes, but well-defined examples of paramagnetic nickel hydride complexes are largely limited to bridging hydrides. Herein, we report the synthesis of an S = 1/2, terminally bound thiolate–Ni^(III)–H complex. This species and its terminal hydride ligand in particular have been thoroughly characterized by vibrational and EPR techniques, including pulse EPR studies. Corresponding DFT calculations suggest appreciable spin leakage onto the thiolate ligand. The hyperfine coupling to the terminal hydride ligand of the thiolate–Ni^(III)–H species is comparable to that of the hydride ligand proposed for the Ni–C hydrogenase intermediate (Ni^(III)–H–Fe^(II)). Upon warming, the featured thiolate–Ni^(III)–H species undergoes bimolecular reductive elimination of H₂. Associated kinetic studies are discussed and compared with a structurally related Fe^(III)–H species that has also recently been reported to undergo bimolecular H–H coupling

An S = ½ iron complex featuring N₂, thiolate, and hydride ligands: Reductive elimination of H₂ and relevant thermochemical Fe-H parameters

Believed to accumulate on the Fe sites of the FeMo-cofactor (FeMoco) of MoFe-nitrogenase under turnover, strongly donating hydrides have been proposed to facilitate N₂ binding to Fe and may also participate in the hydrogen evolution process concomitant to nitrogen fixation. Here, we report the synthesis and characterization of a thiolate-coordinated Fe^(III)(H)(N₂) complex, which releases H₂ upon warming to yield an Fe^(II)–N₂–Fe^(II) complex. Bimolecular reductive elimination of H₂ from metal hydrides is pertinent to the hydrogen evolution processes of both enzymes and electrocatalysts, but well-defined examples are uncommon and usually observed from diamagnetic second- and third-row transition metals. Kinetic data obtained on the HER of this ferric hydride species are consistent with a bimolecular reductive elimination pathway, arising from cleavage of the Fe–H bond with a computationally determined BDFE of 55.6 kcal/mol

Cp* Noninnocence Leads to a Remarkably Weak C–H Bond via Metallocene Protonation

Metallocenes, including their permethylated variants, are extremely important in organometallic chemistry. In particular, many are synthetically useful either as oxidants (e.g., Cp_2Fe^+) or as reductants (e.g., Cp_2Co, Cp*_2Co, and Cp*_2Cr). The latter have proven to be useful reagents in the reductive protonation of small-molecule substrates, including N_2. As such, understanding the behavior of these metallocenes in the presence of acids is paramount. In the present study, we undertake the rigorous characterization of the protonation products of Cp*_2Co using pulse electron paramagnetic resonance (EPR) techniques at low temperature. We provide unequivocal evidence for the formation of the ring-protonated isomers Cp*(exo/endo-η^4-C_5Me_5H)Co^+. Variable temperature Q-band (34 GHz) pulse EPR spectroscopy, in conjunction with density functional theory (DFT) predictions, are key to reliably assigning the Cp*(exo/endo-η^4-C_5Me_5H)Co^+ species. We also demonstrate that exo-protonation selectivity can be favored by using a bulkier acid and suggest this species is thus likely a relevant intermediate during catalytic nitrogen fixation given the bulky anilinium acids employed. Of further interest, we provide physical data to experimentally assess the C–H bond dissociation free energy (BDFE_(C–H)) for Cp*(exo-η^4-C_5Me_5H)Co^+. These experimental data support our prior DFT predictions of an exceptionally weak C–H bond (<29 kcal mol^(–1)), making this system among the most reactive (with respect to C–H bond strength) to be thoroughly characterized. These data also point to the propensity of Cp*(exo-η^4-C_5Me_5H)Co to mediate hydride (H–) transfer. Our findings are not limited to the present protonated metallocene system. Accordingly, we outline an approach to rationalizing the reactivity of arene-protonated metal species, using decamethylnickelocene as an additional example