Form Of L1 Research Articles

Chromium-Thiolate Complex Undergoing C-S Bond Cleavage.

The cleavage of C-S bonds represents a crucial step in fossil fuel refinement to remove organosulfur impurities. Efforts are required to identify alternatives that can replace the energy-intensive hydrodesulfurization process currently in use. In this context, we have developed a series of bis-thiolato-ligated CrIII complexes supported by the L2- ligand (L2- = 2,2'-bipyridine-6,6'-diyl(bis(1,1-diphenylethanethiolate), one of them displaying desulfurization of one thiolate of the ligand under reducing and acidic conditions at ambient temperature and atmospheric pressure. While only 5-coordinated complexes were previously isolated by reaction of L2- with 3d metal MIII ions, both 5- and 6-coordinated mononuclear complexes have been obtained in the case of CrIII, viz., [CrIIILCl], [CrIIILCl2]-, and [CrIIILCl(CH3CN)]. The investigation of the reactivity of [CrIIILCl(CH3CN)] under reducing conditions led to a dinuclear [CrIII2L2(μ-Cl)(μ-OH)] compound and, in the presence of protons, to the mononuclear CrIII complex [CrIII(LN2S)2]+, where LN2S- is the partially desulfurized form of L2-. A desulfurization mechanism has been proposed involving the release of H2S, as evidenced experimentally.

Speech translation for Unwritten language using intermediate representation: Experiment for Viet-Muong language pair

The paper studies an automatic translation method that translates from the text of a language (L1) to the speech of an unwritten language (L2). Normally the written text is used as the bridge to connect a translation module that translates from the text of L1 to the text of L2 and a synthesis module that generates the speech of L2 from the text. In the case of unwritten language, an intermediate representation has to be used instead of the writing form of L2. This paper proposes the use of phoneme representation because of the intimate relationship between phonemes and speech in one language. The proposed method was applied to the Viet-Muong language pair. The Vietnamese text needs to be translated into Muong language in two dialects, Muong Bi - Hoa Binh and Muong Tan Son - Phu Tho, both unwritten. The paper also proposes a phoneme set for each Muong language and applies them to the problem. The evaluation results showed that the translation quality was relatively high in both dialects (for Muong Bi, the fluency score was 4.63/5.0, and the adequacy score was 4.56/5.0). The synthesized speaking quality in both dialects is acceptable (for Muong Bi, the MOS score was 4.47/5.0, and the comprehension score was 93.55%). The results also show that the applicability of the proposed system to other unwritten languages ​​is promising.

Transient but Effective? Captioning and Adolescent EFL Learners’ Spoken Vocabulary Acquisition

This study aims to establish the effects of captioning on enhancing EFL learners’ spoken vocabulary. To this end, a three-month experiment, which involved ten level-appropriate videos from the cartoon series, Olivia, was conducted. A quasi-experiment design was adopted with a total of 118 EFL eighth graders at a junior high school participating in the study. Sixty students were assigned to watch the videos with captions, and the others were assigned to watch them without. To explore if the efficacy of captioning would be modulated by the students’ linguistic competence profiles—an issue that a lot of EFL instructors are currently facing in their teaching—the participants were further subdivided into three groups (high-level, intermediate-level, and low-level) based on their achievements in English. Two types of vocabulary posttest (i.e., form recognition and vocabulary acquisition tests) were administered to evaluate any vocabulary gains. The results of the study indicate that the availability of captions significantly improved the participants’ recognition of form and form-meaning knowledge of novel L2 (English) spoken vocabulary. In addition, in both vocabulary tests, the participants with a higher level of linguistic competence acquired substantially more word gains from captions than their counterparts of lower competence. These results empirically established the efficacy of captioning in enhancing EFL eighth graders’ incidental vocabulary spoken vocabulary gains and suggest that linguistic competence appears to be a crucial factor modulating the pedagogical potency of captioned videos. Based on the findings of this study, some pedagogical implications for employing captioned video materials to enhance EFL middle school students’ language gains are discussed.

Cache Hierarchy-Aware Query Mapping on Emerging Multicore Architectures

One of the important characteristics of emerging multicores/manycores is the existence of “shared on-chip caches,” through which different threads/processes can share data (help each other) or displace each other's data (hurt each other). Most of current commercial multicore systems on the market have on-chip cache hierarchies with multiple layers (typically, in the form of L1, L2 and L3, the last two being either fully or partially shared). In the context of database workloads, exploiting full potential of these caches can be critical. Motivated by this observation, our main contribution in this work is to present and experimentally evaluate a cache hierarchy-aware query mapping scheme targeting workloads that consist of batch queries to be executed on emerging multicores. Our proposed scheme distributes a given batch of queries across the cores of a target multicore architecture based on the affinity relations among the queries. The primary goal behind this scheme is to maximize the utilization of the underlying on-chip cache hierarchy while keeping the load nearly balanced across domain affinities. Each domain affinity in this context corresponds to a cache structure bounded by a particular level of the cache hierarchy. A graph partitioning-based method is employed to distribute queries across cores, and an integer linear programming (ILP) formulation is used to address locality and load balancing concerns. We evaluate our scheme using the TPC-H benchmarks on an Intel Xeon based multicore. Our solution achieves up to 25 percent improvement in individual query execution times and 15-19 percent improvement in throughput over the default Linux-based process scheduler.

A socio-historical account of the formation of the creole language of Antigua

The present paper constructs a socio-historically oriented account of Antiguan Creole (hereafter AC) formation based on the chronology, demographics, economy, and origin and distribution of the population groups of colonial Antigua. During the first decades after the establishment of the colony in the mid seventeenth century until the end of that century, Antigua based its economy on small holdings not dependent on slave labor, where contact among different linguistic groups was so close and direct as to create a second language variety (hereafter L2). By the late seventeenth and early eighteenth centuries, the demographic make-up changed radically as sugar became the dominant crop, enslaved peoples were massively imported, and a plantation economy dominated the island’s affairs. It is during this period that segregation increased, creating a gap between groups of European and African origin, which resulted in a process of restructuring that created a more divergent form of the earlier L2. Thus I argue that AC formation involved both the pre-plantation and the plantation phases, so the creolization process was not completed until the importation of slaves stopped and the balance between the locally-born and the foreign-born population shifted in favor of the former. Furthermore, I survey the language groups that may have been available during both phases and argue that AC formation was modeled on its lexifier during the first decades of its existence but its formation continued afterwards adopting more substrate traits. Therefore, moderate superstrate and substrate positions account for AC formation.

Reduction of nitrile to primary amine using sodium borohydride: Synthesis and protonation of a cis-octahedral macrocyclic nickel(II) complex bearing two 2-aminoethyl pendant arms

The cis-octahedral complex [NiL2](ClO4)2·H2O (1) (L2=C-racemic-1,8-bis(N-2-aminoethyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane), bearing two coordinated N-CH2CH2NH2 pendant arms, has been prepared by a reaction of the N-CH2CN groups of [Ni(L1)(CH3COO)]+ (L1=C-racemic-1,8-bis(cyanomethyl)-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) with NaBH4 in acetonitrile. The trigonal bipyramidal complex [Ni(HL2)](ClO4)3·H2O (2) (HL2=a mono-protonated form of L2), in which the primary amino group of the coordinated N-CH2CH2NH2 group occupies one of the three equatorial positions, has also been prepared by the addition of HClO4 to a methanol solution of 1. The equatorial Ni–N (N-CH2CH2NH2 group) distance (2.076(2)Å) of 2 is similar to other equatorial Ni–N (macrocyclic ring) distances (2.073(2) and 2.075(2)Å), but is significantly shorter than the Ni–N (N-CH2CH2NH2 groups) distances (2.170(3) and 2.190(3)Å) of 1. Interestingly, the coordinated N-CH2CH2NH2 group of 2 is inert to protonation.

Synthesis, structures, and antibacterial activities of two iron(III) complexes with Schiff bases

Two Schiff base iron(III) complexes, [FeL1(AHA)] · H2O (I) and [Fe(L2)2] · ClO4 (II), where AHA is the deprotonated form of acetohydroxamic acid, and L1 and L2 are the anionic form of N,N′-bis(3-ethoxysalicylidene)propane-1,2-diamine and 2-[1-(2-aminopropylimino)ethyl]phenol, respectively, have been synthesized and characterized by physical chemical methods and single crystal X-ray diffraction. Crystallographic data for I: orthorhombic, space group Iba2, a = 20.781(3), b = 23.527(3), c = 10.071(2) A, V = 4923.7(12) A3, Z = 8, R1 = 0.0374, wR2 = 0.0900. Crystallographic data for II: triclinic, space group a = 12.748(1), b = 13.401(1), c = 19.007(1) A, α = 106.623(2)°, β = 97.462(2)°, γ = 112.543(2)°, V = 2784.9(4) A3, Z = 4, R1 = 0.0892, wR2 = 0.2434. X-ray crystal structural study indicated that the coordination environment around each Fe atom in the complexes is a six-coordinated distorted octahedron. The antibacterial activities of the complexes were assayed.

Mixed ligand copper(II) complexes: Synthesis, characterization and DNA cleavage activities

AimThis study was aimed to examine the DNA cleavage ability of the mixed ligand copper complexes. MethodsThe reduced form of Schiff base ligands L1 and L2 (where L1 is 1-(tetrahydrofuran-2-yl)-N-(thiophen-2-ylmethyl)methanamine and L2 is 1-(1H-benzimidazol-2-yl)-N-(tetrahydrofuran-2-ylmethyl)methanamine) were synthesized. Three new mixed ligand mononuclear copper(II) complexes containing tridentate unsymmetrical and bidentate symmetrical ligands were also synthesized. ResultsThe synthesized complexes were characterized using various physicochemical techniques like cyclic voltammetry and elemental analysis, ESI-MS, UV–Visible, Infra red and EPR. All the three complexes however successfully promoted an oxidative cleavage of plasmid DNA, producing single strand break. In addition, mechanistic SC DNA cleavage results show higher DNA cleavage activity in presence of oxidizing agent, due to the presence of hydroxyl radicals. ConclusionsFrom the present study it was concluded that the complexes were able to cleave plasmid DNA oxidatively in the presence of hydrogen peroxide.

Synthesis, characterization and theoretical study of a new asymmetrical tripodal amine containing morpholine moiety

A new asymmetrical tripodal amine, [H3L2]Br3 containing morpholine moiety was prepared from reacting of one equivalent of N-(3-aminopropyl)morpholine and two equivalents of tosylaziridine, followed by detosylation with HBr/CH3COOH. The products were characterized by various spectroscopic methods such as FAB-MS, elemental analysis, 1H and 13C NMR spectroscopy. The crystal structure of the hydrobromide salt of the latter amine, [H3L2]Br3, was also determined. For triprotonated form of the ligand L2 we can consider several microspecies and/or conformers. A theoretical study at B3LYP/6-31G∗∗ level of theory showed that the characterized microspecies is the most stable microspecies for the triprotonated form of the ligand. It was shown that the experimental NMR data for [H3L2]Br3 in solution have good correlation with the corresponding calculated data for the most stable microspecies of [H3L2]3+ in the gas phase.

Two forms of ribosomal protein L2 of Escherichia coli that inhibit DnaA in DNA replication

We purified an inhibitor of oriC plasmid replication and determined that it is a truncated form of ribosomal protein L2 evidently lacking 59 amino acid residues from the C-terminal region encoded by rplB. We show that this truncated form of L2 or mature L2 physically interacts with the N-terminal region of DnaA to inhibit initiation from oriC by apparently interfering with DnaA oligomer formation, and the subsequent assembly of the prepriming complex on an oriC plasmid. Both forms of L2 also inhibit the unwinding of oriC by DnaA. These in vitro results raise the possibility that one or both forms of L2 modulate DnaA function in vivo to regulate the frequency of initiation.

Microwave-assisted synthesis of 3-hydroxy-4-pyridinone/naphthalene conjugates. Structural characterization and selection of a fluorescent ion sensor

Two novel 3-hydroxy-4-pyridinone/naphthalene conjugates (L1 and L2) with different distances between the chelating and the fluorescent moieties were synthesized using conventional heating and microwave irradiation achieving a shorter reaction time. The structure of both compounds was confirmed by X-ray crystallography, revealing that these compounds were isolated as hydrochloride salts in dihydroxypyridinium forms. In solution and in the presence of a base, the tautomeric keto forms may be obtained as it was elucidated by NMR analysis. The dihydroxypyridinium form of L1 exhibits fluorescence at 450 nm, both in ACN and DMSO, whereas the corresponding keto form exhibits fluorescence at 365 nm. In contrast, the dihydroxypyridinium form of L2 only fluoresces in DMSO, exhibiting a band at 340 nm, while the keto form is non-fluorescent. These distinct fluorescent behaviors reveal that the tautomeric form in which the ligands are isolated and the distance between the chelating and fluorescent functions strongly influences their fluorescence properties. Ligand L1 exhibits better fluorescence properties and its fluorescence intensity is quenched in the presence of variable concentration of Cu2+, Zn2+, and Fe3+, thus making it suitable to be used as ion sensor.

Modification of Human Papillomavirus Minor Capsid Protein L2 by Sumoylation

The human papillomavirus (HPV) minor capsid protein L2 plays important roles in the generation of infectious viral particles and in the initial steps of infection. Here we show that HPV-16 L2 protein is sumoylated at lysine 35 and that sumoylation affects its stability. Interestingly, the sumoylated form of L2 cannot bind to the major capsid protein L1, suggesting a mechanism by which capsid assembly may be modulated in an infected cell. Additionally, L2 appears to modulate the overall sumoylation status of the host cell. These observations indicate a complex interplay between the HPV L2 protein and the host sumoylation machinery.

Double-Bridged 1-D Chain Polymers of Zinc and Cadmium Constructed by a Flexible Dipyridyl-Type Linking Ligand: {[ML1.5(NO3)2].(CH3OH)}∞ {M = Zn or Cd; L = (3-py)-CH2-NH-(CH3)C6H3-C6H3(CH3)-NH-CH2-(3-py)}

36 Ligand L3 is a reduced form of L2, and coordination polymers based on ligand L3 have novel intriguing topologies, consistent with our expectation that free rotations about the Ar-NH, NH-CH2, and CH2-(4-py) bonds may be possible. In other words, our previous work demonstrated that reduced species of diimine ligands possess a greatly enhanced structural flexibility, which may create novel polymers that cannot be obtained from the original rigid diimine ligands. As an extension of that work, we decided to reduce ligand L1 and to prepare coordination polymers by employing the resulting reduced ligand. It is worth noting that ligand L1 is a structural isomer of ligand L2 due to the different nitrogen positions in the terminal pyridyl rings. We report herein the preparation of ligand L, (3-py)-CH2-NH-(CH3)C6H3-C6H3(CH3)NH-CH2-(3-py), and structures of its zinc and cadmium coordination polymers.

Selective complexation of 3d metal(ii) ions with multidentate and chiral isomers derived from condensation of 2-pyridinecarboxaldehyde with triethylenetetramine

Condensation of 2-pyridinecarboxaldehyde with a stoichiometric amount of triethylenetetramine in isopropyl alcohol yields a mixture of at least two products, a Schiff dibase L(1) and a cyclization product with two imidazolidine rings L(2), and possibly a Schiff monobase with one imidazolidine ring L(3). The 3d metal(II) salts, Mn(SCN)(2), MnCl(2), CuBr(2), MnI(2) and ZnBr(2), react selectively with L(1) or L(2) in this mixture solution to produce Mn(L(2))(NCS)(2) 1, Mn(L(2))Cl(2) 2, [Cu(L(2))Br]Br x H(2)O 3, [Mn(L(1))]I(2) 4, and [Zn(L(1))][ZnBr(4)] 5 , respectively. The presence of the two imidazolidine rings in the coordinated ligand L(2) of 1-2 generates two chiral carbon centers. The Mn(II) ion coordinates stereo-selectively to the [R,R] or [S,S] form of the L(2) in hexa-coordinate Mn(II) compounds 1 and 2, whereas the Cu(II) ion coordinates with the meso [R,S] form of L(2) in 3.

X-ray spectral analysis of the degradation of Au/Si interphase boundaries in air

The dependence on the energy of primary electrons of the form of the ultrasoft x-ray Si L2,3 and Au N6,7 emission bands is studied in Au/Si structures interacting with the oxygen in air. A method for quantitatively estimating the phase chemical composition and its depth distribution was used, based on an analysis of the shape of the bands and employing the most general integral form for the dependence of the intensity of the x-ray spectra on the energy of the primary electrons. Oxidation was found to cause diffusion of silicon atoms to the surface and produce a fundamental change in the phase composition of the structures that were studied. A characteristic feature of the structure of all the samples was the appearance on their surface of a relatively thick layer of SiO2, whose thickness depends on the initial phase composition of the Au/Si interface.