Column Of Table Research Articles

(Invited) Silicon a New Electrode for Electrochemical Reduction of Nitrates Comparison with Boron-Doped Diamond

Nitrate (NO3 -) ions are one of the world’s most widespread water pollutants. Previous studies on electroreduction of nitrate at cathodes were aimed to selectively convert NO3 - to inert N2. Extensive studies on boron-doped diamond (BDD) have shown that this promising electrode reduces very efficiently the nitrates. Under highly negative potentials, H2 evolution is strongly impeded confirming that the competition between H2 formation and NO3 - reduction at BBD electrode is weak (1). N2 was obtained in acidic solution (2, 3). This result was confirmed at pilot scale (3). However, since several years the goal has changed toward the clean production of a useful product such as ammonia which is formed following the 8 electrons process: NO3 - + 10 H+ + 8 e- à NH4 + +3 H2O. Optimizing the conditions of nitrate electroreduction at BDD electrodes Einaga and al obtained ammonia (4).One drawback is the cost of the BDD electrode and research of new efficient electrodes toward nitrate reduction is highly desirable. Silicon (Si) and diamond (C) belong to the same column of the periodic table. They share numerous properties including crystallographic structure and formation of metal-hydrogen bonds (Si-H or C-H bonds) at the surface. This led us to undertake preliminary studies using monocrystalline heavily doped P-type Si wafer as a new cathode for nitrate reduction. The cyclic voltammetry in HCl and HNO3 solutions showed that Si similarly to BDD electrode exhibited a slow kinetics for H2 evolution illustrated by a very high overvoltage for water decomposition (Fig. 1).The products formed during NO3 - reduction were analyzed following a procedure developed during the experiments with BDD electrodes. Electrolysis were done during 6 hours under constant potential using an electrochemical cell with a double compartment separated by a Nafion membrane. The starting solution was 1M NO3 - solution at pH 0.5 permitting to avoid the formation of toxic NO2 - nitrite species. Reduction products in solution and gases were analyzed after the electrolysis, using spectrophotometry and gas chromatography. The potential applied to the cathode varied from -3 to -5 V/SCE. The amount of reduced nitrates during the electrolysis increased linearly with the cathodic polarization for both Si and BDD electrodes. The electrolysis efficiency with the Si electrode was ~70 % that of BDD. The faradic efficiency of H2 production at the Si electrode decreased from 65 to 15 % at -3 and -5 V, respectively with a 5 % minimum at -4V. NH4 + was found to be the major product formed at -4V. The stability of the Si electrode was fairly good with an etching limited to a thickness of 1 µm/cm2 per electrolysis. That may be due to a local formation of OH- (reduction of H2O). The interest of using Si as an alternative electrode for the reduction of nitrate deserves further investigations. References1). C. Lévy-Clément, N.A. Ndao, A. Katty, M. Bernard, A. Deneuville, C. Comninellis, A. Fujishima, Diamond and Related Materials 12, 606–612, 2003.2).V. Georgeaud, F. Omnes, J.-P Gauthier, C. Lévy-Clément, Nitrates in water: electro-reduction to nitrogen gas with BDD electrodes. Optimization of reaction conditions and development of great size electrodes. RITEAU (French national research program), Nitradiam report n°103 2 90 6067, 20083).V. Georgeaud, A. Diamand, D. Borrut, D. Grange and M. Coste , Water Science and Technology, 63-2, 20114).P. Kuang, K. Natsui, C. Feng, Y. Einaga, Chemosphere 251, 126364 (2020) and references therein Figure 1

Participation of transition metal atoms in noncovalent bonds.

The existence of halogen, chalcogen, pnicogen, and tetrel bonds as variants of noncovalent σ and π-hole bonds is now widely accepted, and many of their properties have been elucidated. The ability of the d-block transition metals to potentially act as Lewis acids in a similar capacity is examined systematically by DFT calculations. Metals examined span the entire range of the d-block from Group 3 to 12, and are selected from several rows of the periodic table. These atoms are placed in a variety of neutral MXn molecules, with X = Cl and O, and paired with a NH3 nucleophile. The resulting M⋯N bonds tend to be stronger than their p-block analogues, many of them with a substantial degree of covalency. The way in which the properties of these bonds is affected by the row and column of the periodic table from which the M atom is drawn, and the number and nature of ligands, is elucidated.

Comparison of Trend Parameters and Seasonal Indices in the Presence and Absence of Missing Values of Exponential Trend-Cycle in Time Series Analysis

This study examines the comparison of trend cycle and seasonal components in the presence and absence of missing observations. The method adopted in this study is based on the row, column and overall means of the time series arranged in a Buys-Ballot table with m rows and s columns. The method assumes that (1) Only one data is missing at a time in the Buys-Ballot table (2) the trending curve is exponential (3) the modal structure is additive. The study indicates that, the estimation of the missing observations as they occur consecutively with the errors being normally distributed. Results indicate that, the differences in the trend parameters for both situations are insignificant because they are approximately the same. In the case of corresponding seasonal effects, significant differences existed on the points in which there are missing values in the column of the Buys-Ballot table.

First-Principles Study of the Doping Effect in Half Delithiated LiNiO2 Cathodes

A systematic theoretical study of dopants in a half-delithiated lithium nickel oxide (Li0.5NiO2) cathode is performed to determine the preferred occupation sites, dopant ion migration, and suppression of oxygen evolution. Dopants considered include Li, B, Na, Mg, Al, Si, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Y, Zr, Nb, Mo, In, Sn, Sb, La, Ce, Ta, and W. For the nontransition metal dopants, the energy barrier governing dopant migration is correlated with the number of valence shell electrons so that it increases from left to right across a row of the periodic table. For these dopants, the energy barrier also decreases moving down a column of the periodic table. For transition metal dopants, the energy barrier depends on the number of unpaired valence electrons of the dopant, so that the energy barrier is maximum near the middle of a transition metal row. Oxygen stability is studied by calculating the gap between O-2p and Ni-3d band centers. Most dopants that prefer occupying octahedral sites in the transition metal layer bring higher oxygen stability. In particular, oxygen stability is enhanced mostly by Mo, Sb, and W doping.

A Female-Centered Evaluation of Growth, Survival, Reproduction, and Demography in the Salamander Desmognathus quadramaculatus

In the present report, I evaluate life history and demography for two populations of the Black-bellied Salamander, Desmognathus quadramaculatus, in the Cowee and Nantahala Mountains, North Carolina, using published data on growth of females, fecundity, and larval growth and development to generate life tables and metabolic life histories for each population. I assumed that females in these populations reproduce biennially, beginning at ages 7–8 years and 8–10 years in Cowee and Nantahala populations, respectively. In deriving life tables, I posited stationary populations wherein net reproductive rate (R0) equaled 1.0 and population growth rate (r) equaled 0. Fecundity (mx column of the life table) was based on counts of ovarian follicles in gravid females. Survival values (lx column of the life table) were generated by an iterative process that yielded a value of R0 = 1.0. I projected the life spans in each population to 25 years. The demographic models developed by the procedure allowed comparison with those reported earlier for D. monticola and D. ocoee. Age at first reproduction and generation time are key contributors to variation in body size and life history in Desmognathus.

Structural and spectroscopic study of neutral dioxides MO2 (M = B, Al, Ga, In, Tl)

Both ab initio Hartree-Fock self consistent field (HF-SCF) with Cluster Coupled (CCSD(T)) and Density Functional Theory with B3LYP functional, high level theories are adopted for structural study of different dioxides MO2 (M = B, Al, Ga, In and Tl). A geometry optimization is performed using the avtz, aug-cc-pwcvnz (nz = tz; qz; 5z), 6–311++G** and Lanl2DZ basis sets. Vibration frequencies are reported for optimized geometries. We also report calculated M-O and O-O bond lengths, O-M-O and M-O-O, bond angles for stable isomers. Our calculations indicate that there are five possible isomers with linear or folded shapes. Some discrepancies with previous results are noted, on the other hand, according to our CCSD(T) calculations, MO2 molecule (M = B, Al and Ga) is in ground state when it is linear and symmetric O-M-O (2Πg), then in a higher energy state with the cyclic isomer (2A2, or 2A1) and in more higher state when it is dissymmetric M-O-O (2A’, 2∑+), B3LYP and CCSD(T) results agree on energetic ordering of various isomeric forms for BO2, AlO2,InO2 and TlO2 systems, while there is disagreement for GaO2, molecule. HOMO-1, HOMO, LUMO and LUMO + 1 molecular orbitals for the most stable structures are given as well. NBO analysis is performed to study the superoxide 2A2 and its stability which evolves according to electropositivity of metal along the 13th column of periodic table.

Development of the knowledge of exercise during pregnancy scale

Objective: Benefits of exercise in pregnancy on maternal and fetal health are well-documented, whereas physical activity participation and knowledge of exercise during pregnancy are limited among pregnant women. This research purposed to develop a tool to measure knowledge of exercise during pregnancy. Material and Methods: This is a methodological study. After review of the literature, a pool of items was created. These items were regulated into a Likert-type scale. The content validity of the 27-item pilot-scale was assessed by expert review. The pilot-scale was applied online to women aged over 18 years with a history of at least one full-term live delivery. After the pilot application, validity and reliability were analyzed. Results: The content validity ratios (CVR) of items were between 0.500-0.900, and the content validity index (CVI) of the scale was 0.690. The scale underwent item analysis for reliability, and factor analysis for validity assessment. Subsequently, a total of 15 items were removed due to increasing Cronbach's alpha coefficient (k=10) and if having a communality value below 0.30 in the extraction column of the communalities table (k=5). The remaining 12 items were collected under a single factor with an eigenvalue of 5.731 that explained 47.8% of the variance. The scale was found to be highly reliable (Cronbach's alpha 0.894, Spearman-Brown split-half reliability coefficient 0.796, Guttman split-half reliability coefficient 0.792). The confirmatory factor analysis indicated good fit for the 12-item scale. Conclusions: The newly developed 12-item Knowledge of Exercise during Pregnancy Scale is valid and reliable for use with Turkish women to assess knowledge of exercise during pregnancy.

Physicians' attitude scale towards doping: A scale development study

Objective: To develop the "Physicians' Attitude Scale towards Doping" and provide the validity and reliability of the scale in Turkish physicians. Material and Methods: This quantitative research design study followed the scale development study procedures. Initially, the 47-items pool was submitted for academicians’ expert opinion. Thirty-two items with a content validity ratio value below 0.56 were removed from the scale after expert opinion. Thus, the content validity ratio was calculated as 0.67-1.00, and the content validity index was 0.844. After the expert opinion, the pilot-scale with 15 items was applied to the physicians by reaching the sample size of at least 10 times the number of items. According to the answers given to the pilot scale, validity and reliability analyzes of the scale were made. Results: A 15-item pilot scale was applied to 292 physicians. Four items that reduce the Cronbach's alpha coefficient and an item with a value below 0.30 in the extraction column of the communalities table were excluded from the scale. Item discrimination index values of the scale were found to be appropriate (p˂0.001). All of the item load distributions were found above 0.50, and the item quality was good. The total variance rate explained by this factor is 59.3%. Cronbach’s alpha reliability coefficient of the whole scale was calculated as 0.761. The fit indices of the model tested with confirmatory factor analysis were good. Conclusion: The "Physicians' Attitude Scale towards Doping" was developed, and the validity and reliability of the two factor and total 10-item scale were provided.

Controlling the Formation Process of Methylammonium‐Free Halide Perovskite Films for a Homogeneous Incorporation of Alkali Metal Cations Beneficial to Solar Cell Performance

AbstractIncorporating multiple cations of the 1A alkali metal column of the periodic table (K+/Rb+/Cs+) to prepare perovskite films is promising for boosting photovoltaic properties but requires a uniform distribution. The effects of NH4Cl additives and alkali metal cations (K+/Rb+/Cs+) on the one‐step formation process of methylammonium‐free, formamidinium‐based, iodide perovskite films are analyzed in a step‐by‐step manner. NH4Cl improves the solubility of PbI2 in solution by forming an intermediate and then favors the perovskite phase formation. Moreover, during the annealing process, this additive is shown to increase grain size, to improve crystallinity and to suppress PbI2 formation. K at low concentration is always homogeneously distributed across the film thickness. On the other hand, Cs is more concentrated at the surface and Rb in the depths of pristine films. With NH4Cl additives, these two alkali metals are more homogeneously distributed because NH4Cl slows down the movement of Cs+ and Rb+, it changes the growth direction of the perovskite film, making the overall crystallization quality improved and the distribution more uniform. It results in perovskite films with large monolithic grains. Combined with a perovskite film surface treatment with n‐propylammonium iodide, a high stabilized power conversion efficiency of 22.04% is reached.

Rigel: Transforming Tabular Data by Declarative Mapping.

We present Rigel, an interactive system for rapid transformation of tabular data. Rigel implements a new declarative mapping approach that formulates the data transformation procedure as direct mappings from data to the row, column, and cell channels of the target table. To construct such mappings, Rigel allows users to directly drag data attributes from input data to these three channels and indirectly drag or type data values in a spreadsheet, and possible mappings that do not contradict these interactions are recommended to achieve efficient and straightforward data transformation. The recommended mappings are generated by enumerating and composing data variables based on the row, column, and cell channels, thereby revealing the possibility of alternative tabular forms and facilitating open-ended exploration in many data transformation scenarios, such as designing tables for presentation. In contrast to existing systems that transform data by composing operations (like transposing and pivoting), Rigel requires less prior knowledge on these operations, and constructing tables from the channels is more efficient and results in less ambiguity than generating operation sequences as done by the traditional by-example approaches. User study results demonstrated that Rigel is significantly less demanding in terms of time and interactions and suits more scenarios compared to the state-of-the-art by-example approach. A gallery of diverse transformation cases is also presented to show the potential of Rigel's expressiveness.

The Effect of Game on the Students’ Tense Achievment

This research was conducted to investigate the effect of using game on the seventh-grade students’ tense achievement at SMPN 2 Balung-Jember. The primary data of this research were collected from the students’ scores of tense test. The primary data were collected from the post-test to compare the two different groups after treatment and analyzed the result by using independent sample T-Test (SPSS). Based on the calculation, the result of this research showed that there was a significant effect of using game on the seventh-grade students’ tense achievement. It was proved by the value of significant column of t-test table by using SPSS software, and the result was 0.045 which was lower than 0.05 (significant level of 5%). The research results proved that there was a significant effect of using game on the seventh-year students’ tense achievement at SMPN 2 Balung-Jember. Therefore, it is recommended for the English teacher to use game as an alternative technique in teaching tenses.

Securing Logins in Electronic Examination Systems for Tertiary Institutions Using Quick Response Code (QR) Technology and Multiple Hashing Algorithms

This work is aimed at adding an extra layer of security to the login process of an electronic examination system as security has been identified as one of the critical success factors in the management of such exams. It proposes to secure the login process of an e-exam system through authentication and encryption to control access and avoid impersonation. A model of the e-exam system with Quick Response (QR) code generation capability was designed where a student’s matriculation number is accepted as input which is then converted into a two-dimensional bar code using a QR generator. Outputs from the QR code generator are then secured by encryption using MD5 and SHA-224 encryption algorithms. MD5 algorithm produces a 32-bit hash value which is further encrypted using SHA-224 that produces a resulting 56-bit hash value that is then saved in the password column of the user table in the database. This research resulted in a secure and web-based electronic examination authentication system implemented and tested on a client-server architecture. Performance evaluation of the developed system revealed that it is fast and effective, capable of authenticating students in an average of 0.624 seconds when the smartphone flashlight is off, and 0.318 seconds with flashlight turned on and consequently, resistant to brute force attacks. This paper fulfils an identified need to develop an electronic exam system that not only secures the question bank but equally ensures the security of the login process as well as the login details using a combination of two security techniques.

Transition Metal Chain Complexes Supported by Soft Donor Assembling Ligands.

The chemistry of discrete molecular chains constituted by metals in low oxidation states, displaying metal-metal proximity and stabilized by suitable metal-bridging, assembling ligands comprising at least one soft donor atom is comprehensively reviewed; complexes with a single (hard or soft) bridging atom (e.g., μ-halide, μ-sulfide, or μ-PR2 etc.) as well as "closed" metal arrays (that fall in the realm of cluster chemistry) are excluded. The focus is on transition metal-based systems, with few excursions to cases combining transition and post-transition elements. Most relevant supporting ligands have neutral C, P, O, or S donor (mainly, N-heterocyclic carbene, phosphine, ether, thioether) or anionic donor (mainly phenyl, ylide, silyl, phosphide, thiolate) groups. A supporting-ligand-based classification of the metal chains is introduced, using as the classifying parameter the number of "bites" (i.e., ligand bridges) subtending each intermetallic separation. The ligands are further grouped according to the number of donor atoms interacting with the metal chain (called denticity in the following) and the column of the Periodic Table to which the set of donor atoms belongs (in ascending order). A complementary metal-based compilation of the complexes discussed is also provided in a concise tabular form.

Diatomic molecules’ enigmatic constancy as the product of their dissociation energy and interatomic distance

ABSTRACT In this contribution, we show that the product dissociation energy (D) × interatomic distance (R) with regards to a straightforward taxonomy of diatomic molecules comes to assume a relatively high and virtually constant value. It is so much so that the heavier the diatomic molecules at hand, the closer DxR approaches e 2 (where e is the elementary charge intensity in esu). This occurrence is studied herein separately under families arranged from chemically-alike diatomic molecules. Each family (such as the set made of ‘pairs of strictly alkali atoms’, or ‘pairs of strictly halogen atoms’, or ‘pairs of alkali-halogen atoms’, etc), is thus composed of diatomic molecules formed of atoms bearing similar electronic configurations; whereby we initially ended up dealing with 18 families in total. In addition to those, we brought together 10 more families of diatomic molecules each composed of heavy metal atoms belonging respectively to each of the ten columns drawn from the three rows of heavy metals under the Periodic Table, and observed an even better conformance. [Sc2, Y2, La2] is the first family in question; [Ti2, Zr2, Hf2] and [Va2, No2, Ta2] are the next two families; [Zn2, Cd2, Hg2] delineates the last family of heavy metal diatomic molecules of concern. Let us stress that each of these sets embodies diatomic molecules made of heavy metal atoms belonging to the given column of the Periodic Table; thus, bearing alike electronic configurations. We further brought together 5 more families made of heavy metal hydrides, oxides, chlorides, and alkalines. We were motivated to undertake the present research in the light of our insight with regards to (i) the general non-opacity character of neutral bodies vis-à-vis electrical field transmission, and thence (ii) the attractional electric property of neutral bodies – which underlines the disclosed constancy where, particularly for diatomic molecules comprising heavy atoms, the increase in DxR happens to get aligned with the increase in atomic weight 1 (A1) × atomic weight 2 (A2).

Linear strands of edge ideals of multipartite uniform clutters

We construct the first linear strand of the minimal free resolutions of edge ideals of d -partite d -uniform clutters. We show that the first linear strand of such ideals are supported on relative simplicial complexes . In the case that the edge ideals of such clutters have linear resolutions, we give an explicit and surprisingly simple description of their minimal free resolutions, generalizing known resolutions for edge ideals of Ferrers graphs and hypergraphs and co-letterplace ideals. As an application, we show that the Lyubeznik numbers that appear on the last column of the Lyubeznik table of the cover ideal of such clutters are Betti numbers of certain simplicial complexes. Furthermore, we restate a characterization for edge ideals of d -partite d -uniform clutters which have linear resolutions based on the recent characterization of arithmetically Cohen-Macaulay sets of points in multiprojective spaces.

Controlling the Formation Process of Methylammonium-Free Halide Perovskite Films for a Homogeneous Incorporation of Alkali Metal Cations Beneficial to Solar Cell Performances

Incorporating multiple cations of the Ia alkali metal column of the periodic table (K+/Rb+/Cs+) to prepare m-AMCs perovskite film is promising for boosting the photovoltaic properties. However, contrary to K+, both Cs+ and Rb+ suffer from non-uniformity at the origin of performance and stability losses. In this paper, Ammonium chloride (NH4Cl) additive is shown to address this concern. We analyze step-by-step the effects of NH4Cl Additive and Alkali Metal Cations (K+/Rb+/Cs+) on the one-step film formation process of methylammonium-free, formamidinium-based, halide perovskites. First, we highlight the action of NH4Cl additive on the spin-coating and the anti-solvent dripping processes. We show that it improves the solubility of PbI2 in solution by forming an intermediate and then favor the perovskite phase formation. Then, we investigate the annealing process by introducing depth profile evolution monitoring by the glow discharge optical emission spectroscopy (GD-OES) technique. The real-time distribution changes of m-AMCs in the film upon annealing at 155°C is visualized. We show that K at low concentration is homogeneously distributed throughout the film. Cs is more concentrated at the surface and Rb in the film depth. With NH4Cl additive, these two alkali metals are more homogeneously distributed. We show that NH4Cl can slow down the movement of m-AMCs so that they are better evenly distributed into the perovskite layer. Moreover, it changes the growth direction of the perovskite film changes, making the overall crystallization quality improved and the distribution more uniform. It results in perovskite films with large monolithic grains, permitting a high stabilized power conversion efficiency (PCE) over 21%. Finally, by combining AC additive and film surface treatment with n-propylammonium iodide (PAI), the performance was further upgraded at a stabilized PCE of 22.04%.

Chemical Bonding in Chalcogenides: The Concept of Multicenter Hyperbonding.

The precise nature of chemical-bonding interactions in amorphous, and crystalline, chalcogenides is still unclear due to the complexity arising from the delocalization of bonding, and nonbonding, electrons. Although an increasing degree of electron delocalization for elements down a column of the periodic table is widely recognized, its influence on chemical-bonding interactions, and on consequent material properties, of chalcogenides has not previously been comprehensively understood from an atomistic point of view. Here, a chemical-bonding framework is provided for understanding the behavior of chalcogenides (and, in principle, other lone-pair materials) by studying prototypical telluride nonvolatile-memory, "phase-change" materials (PCMs), and related chalcogenide compounds, via density-functional-theory molecular-dynamics (DFT-MD) simulations. Identification of the presence of previously unconsidered multicenter "hyperbonding" (lone-pair-antibonding-orbital) interactions elucidates not only the origin of various material properties, and their contrast in magnitude between amorphous and crystalline phases, but also the very similar chemical-bonding nature between crystalline PCMs and one of the bonding subgroups (with the same bond length) found in amorphous PCMs, in marked contrast to existing viewpoints. The structure-property relationship established from this new bonding-interaction perspective will help in designing improved chalcogenide materials for diverse applications, based on a fundamental chemical-bonding point of view.

Fuzzy request handler for Mongo QL derived from SQL

Relational DBMS are often used to store fuzzy values, but problems arise with putting such data in a tabular form. Moreover, there appears a problem of storing both the crisp and fuzzy data related to one subject domain in one column of a relational table. This article considers the mechanism of storing crisp and fuzzy values and linguistic variables in the document-oriented Mongo DBMS. The data are stored in the collection as GeoJSON geometry; different geometries are used for different data options. The possibility of storing crisp scalar values, crisp value sets, crisp value intervals and fuzzy values in the collection documents is described. For data processing by means of SQL queries, the context-free grammar of the SQL subset is described, according to which lexer and parser are generated. In order to form the structure of an abstract syntactic tree, a corresponding object model has been implemented. A translator application has been developed, which allows converting SQL queries related to the crisp and fuzzy data into Mongo QL queries. The algorithm of fuzzy queries translation process is suggested; the geometrical interpretation of data comparison operations is described. The examples show the options of fuzzy comparison operations for different value options.

Groups with few p′-character degrees

We prove a variation of Thompson's Theorem. Namely, if the first column of the character table of a finite group G contains only two distinct values not divisible by a given prime number p>3, then Opp′pp′(G)=1. This is done by using the classification of finite simple groups.

Complex group algebras of almost simple unitary groups

The aim of this article is to contribute to a question of R. Brauer that “when do non-isomorphic groups have isomorphic complex group algebras?” Let H and G be finite groups where and let denote the first column of the complex character table of H. In this article, we show that if then provided that q + 1 divides neither n nor n – 1. Consequently, it is shown that G is uniquely determined by the structure of its complex group algebra. This in particular extends a recent result of Bessenrodt et al. [Algebra Number Theory 9 (2015), 601–628] to the almost simple groups of arbitrary rank.