Tandem Manner Research Articles

Fluency versus Accuracy within the Libyan Context of English Language Teaching

All through my long experience of teaching English as a foreign language, there is a problem that I always have to deal with in interacting with my students. That problem is the misconception that so many of my students have. It is the understanding that being fluent means being a good user of English. This type of students are faced with another type of students who believe that being accurate is the name of the game in English language learning. Needless to say that both types of students are equally wrong in their assumptions. 
 This article tries to correct the said assumptions by clarifying the complementary nature of the two elements of fluency and accuracy. After a brief introduction, the article comes in three sections: 
 Section One: This section is merely an attempt to review the versatile definitions of the two elements of fluency and accuracy as presented by different leading authorities in the field of English language teaching. 
 Section Two: This section discusses the importance of fluency and accuracy in any language/ learning process as well as showing the complementary nature of the two elements. 
 Section Three: As the discussion developed in sections one and two, it became obvious that the two elements of fluency and accuracy must be treated in a tandem manner which means that you cannot have one without the other. This brought me face-to-face with the need for striking a balance between the two elements. Up until this stage, the third section was intended to be allocated to the issue of carrying out the needed change so that striking the balance becomes feasible. The required change proved to be of a great magnitude. The result was a complete change of the structure of this article. The initial plan was to conclude the article with a suggestion on how to strike the balance. This proved to be not proper due to the said magnitude of the change; therefore I sufficed with discussing and proving the importance of striking the required balance between fluency and accuracy without touching on planning and implementing the said change. Consequently, a package of three articles needs to be finished before touching on the issue of striking the said balance. The hoped articles would be on ‘What’ needs to be changed, ‘Who’ is going to be the agent of the change, and “How’ is the change going to be implemented.

Photo-Electro Active Nanocomposite Silk Hydrogel for Spatiotemporal Controlled Release of Chemotherapeutics: An In Vivo Approach toward Suppressing Solid Tumor Growth.

Conventional systemic chemotherapeutic regimens suffer from challenges such as nonspecificity, shorter half-life, clearance of drugs, and dose-limiting toxicity. Localized delivery of chemotherapeutic drugs through noninvasive spatiotemporally controllable stimuli-responsive drug delivery systems could overcome these drawbacks while utilizing drugs approved for cancer treatment. In this regard, we developed photoelectro active nanocomposite silk-based drug delivery systems (DDS) exhibiting on-demand drug release in vivo. A functionally modified single-walled carbon nanotube loaded with doxorubicin (DOX) was embedded within a cross-linker free silk hydrogel. The resultant nanocomposite silk hydrogel showed electrical field responsiveness and near-infrared (NIR) laser-induced hyperthermal effect. The remote application of these stimuli in tandem or independent manner led to the increased thermal and electrical conductivity of nanocomposite hydrogel, which effectively triggered the intermittent on-demand drug release. In a proof-of-concept in vivo tumor regression study, the nanocomposite hydrogel was administered in a minimally invasive way at the periphery of the tumor by covering most of it. During the 21-day study, drastic tumor regression was recorded upon regular stimulation of nanocomposite hydrogel with simultaneous or individual external application of an electric field and NIR laser. Tumor cell death marker expression analysis uncovered the induction of apoptosis in tumor cells leading to its shrinkage. Heart ultrasound and histology revealed no cardiotoxicity associated with localized DOX treatment. To our knowledge, this is also the first report to show the simultaneous application of electric field and NIR laser in vivo for localized tumor therapy, and our results suggested that such strategy might have high clinical translational potential.

Effects of Inlet and Outlet Ports of Ventilated Square Cavity on Flow and Heat Transfer

This paper deals with numerical simulations of forced convection from a pair of identical cylinders arranged in tandem manner inside a square cavity of single inlet and outlet ports. The gap distance between the cylinders is fixed with half of square length. The main purpose of this study is to see the effect of inlet and outlet port positions on fluid flow and heat transfer rate. The governing equations of continuity, momentum and energy have been solved using finite-volume method in laminar, steady and two dimensional directions. The work has been done in the range of these conditions: Re = 1 to 40, at fixed Pr = 7.01. Three positions of inlet and outlet port have been selected. The mean results of flow patterns and distribution temperature are illustrated under the contours of streamline and isotherm respectively. The drag and lift coefficients of each cylinder is computed and discussed. The average Nusselt number of both cylinders is also presented and discussed. It was found that the inlet and outlet ports have significant effects on heat transfer from the confined cylinders.

Copper-catalyzed synthesis of α-ketoamides using water and dioxygen as the oxygen source.

The reaction employing H2O and O2 as the co-oxygen source in the catalytic synthesis of α-ketoamides is described. This copper-catalyzed reaction is carried out in a tandem manner constituted by the hydroamination of alkyne, hydration of vinyl–Cu complex and subsequent oxidation. Isotope labeling and radical capture experiments reveal that the oxygen atom of α-ketone at α-ketoamides derives from O2 and the oxygen atom of amide group originates from H2O.

Synthesis of N-heterocycles containing 1,5-disubstituted-1H-tetrazole via post-Ugi-azide reaction.

Ugi-azide four-component reaction (UA-4CR) as development on Ugi four-component reaction (U-4CR) is the condensation reaction involving an aldehyde, an amine, an isocyanide, and an azide source. Nowadays, UA-4CR has been employed for the efficient and facile production of 1,5-disubstituted-1H-tetrazoles (1,5-DS-1H-Ts). Interestingly, the combination of 1,5-DS-1H-Ts with suitable post-transformations in a tandem manner results in the construction of various classes of heterocyclic compounds bearing 1,5-DS-1H-T moiety. This review aims to provide the application of diverse post-Ugi-azide reaction in the preparation of different N-heterocyclic compounds bearing 1,5-DS-1H-T such as substituted and fused 1,5-DS-1H-Ts.

Transition‐Metal‐Free Deconstructive Lactamization of Piperidines

One of the major challenges in organic synthesis is the activation or deconstructive functionalization of unreactive C(sp3 )-C(sp3 ) bonds, which requires using transition or precious metal catalysts. We present here an alternative: the deconstructive lactamization of piperidines without using transition metal catalysts. To this end, we use 3-alkoxyamino-2-piperidones, which were prepared from piperidines through a dual C(sp3 )-H oxidation, as transitory intermediates. Experimental and theoretical studies confirm that this unprecedented lactamization occurs in a tandem manner involving an oxidative deamination of 3-alkoxyamino-2-piperidones to 3-keto-2-piperidones, followed by a regioselective Baeyer-Villiger oxidation to give N-carboxyanhydride intermediates, which finally undergo a spontaneous and concerted decarboxylative intramolecular translactamization.

Transition‐Metal‐Free Deconstructive Lactamization of Piperidines

AbstractOne of the major challenges in organic synthesis is the activation or deconstructive functionalization of unreactive C(sp3)–C(sp3) bonds, which requires using transition or precious metal catalysts. We present here an alternative: the deconstructive lactamization of piperidines without using transition metal catalysts. To this end, we use 3‐alkoxyamino‐2‐piperidones, which were prepared from piperidines through a dual C(sp3)–H oxidation, as transitory intermediates. Experimental and theoretical studies confirm that this unprecedented lactamization occurs in a tandem manner involving an oxidative deamination of 3‐alkoxyamino‐2‐piperidones to 3‐keto‐2‐piperidones, followed by a regioselective Baeyer–Villiger oxidation to give N‐carboxyanhydride intermediates, which finally undergo a spontaneous and concerted decarboxylative intramolecular translactamization.

Downward seepage effects on dynamics of scour depth and migrating dune-like bedforms at tandem piers

The present study focuses on multi-scale statistical characterization of scour depth at tandem piers and migrating dune-like bedforms forming behind the piers in downward seepage affected alluvial channel, using an experimental approach. Experiments were conducted using two circular piers arranged in a tandem manner for no seepage, 10% seepage, and 15% seepage condition. The erosive capacity of reversal flow is hindered with downward seepage, which results in reducing velocity and Reynolds stress near the bed at upstream of piers in case of seepage runs. The bed elevation of the scoured region is decreasing with the increasing seepage percentage and the growth in scour depth is diminishing with time. The celerity of scour depth is decreasing with time as well as decreasing with increasing downward seepage. Probability density function of bedform elevation has positive tail slightly thicker than the Gaussian.

О звуковысотной организации знаменного распева в аспекте дешифровки

The issue of transcription of Early Russian Znamenny Chants into contemporary notation has a deciphering character and remains relevant for notation not provided with aiding deciphering marks. The approach towards computer-based aid of the process of deciphering is based by use of Dvoznamenny chant books of the late 17th and early 18th centuries. The complexity of the deciphering is stipulated by the fact that the Znamenny signs may contain a multitude interpretations of musical notation. The algorithms created by us make it possible to recreate correctly the rhythmic structure of the chants for 95–98% of the signs (znameny) in various voices (glasy). However, the precision of the reconstruction of the pitch constituent is much less – it is approximately 60–80%. This stipulates the necessity for more detailed research of the pitch organization of the Znamenny chant. The work carries out a quantitative analysis of the pitch-related transitions from one znamya (sign) to the next for all sorts of combinations of pairs of znamya (signs) or bigrams presented in the musical texts of dvoznamenniks with preliminarily eliminated marks (pomety) of scalesteps and indications (three Oktoechoses and Heirmologies). The obtained statistics of the acceptable intervals may be used during the process of deciphering of the unmarked notation for the correction of the variants inconsistent with it. Examples are brought of znamenny (sign) bigrams which demonstrate unexpected peculiarities of the Znamenny chant practically unilluminated in musicology. Concurrently questions are touched upon illuminating the definition of the concept of a “line,” the demonstration of bigram indicators of the structures of popevkas, peculiarities of the chants of znameny (signs) repeating in a tandem manner, etc. The work has been carried out with the support of the program of fundamental scholarly studies of the Siberian Branch of the Russian Academy of Sciences No. I.5.1., project No. 0314-2019-0015, as well as through the partial financial assistance of the Russian Foundation of Fundamental Studies, project No. 16-07-00812. Keywords: Znamenny chant, Dvoznamenniks, note-staff reconstruction, popevkas, bigrams.

Aeroacoustic Self-Oscillations of the Gas Near Two Plates in a Channel

Aeroacoustic self-oscillations of the gas near two thin plates arranged in a tandem manner in a rectangular channel are studied in a two-dimensional formulation. A bifurcation of natural frequencies depending on the distance between the plates is detected, and the frequency of selfoscillations is found as a function of the plate length and the distance from the channel walls. The fields of pressure and gas velocities in the examined range of oscillations are constructed.

Ethanol generation, oxidation and energy production in a cooperative bioelectrochemical system

Integrating in situ biofuel production and energy conversion into a single system ensures the production of more robust networks as well as more renewable technologies. For this purpose, identifying and developing new biocatalysts is crucial. Herein, is reported a bioelectrochemical system consisting of alcohol dehydrogenase (ADH) and Saccharomyces cerevisiae, wherein both function cooperatively for ethanol production and its bioelectrochemical oxidation. Here, it is shown that it is possible to produce ethanol and use it as a biofuel in a tandem manner. The strategy is to employ flexible carbon fibres (FCF) electrode that could adsorb both the enzyme and the yeast cells. Glucose is used as a substrate for the yeast for the production of ethanol, while the enzyme is used to catalyse the oxidation of ethanol to acetaldehyde. Regarding the generation of reliable electricity based on electrochemical systems, the biosystem proposed in this study operates at a low temperature and ethanol production is proportional to the generated current. With further optimisation of electrode design, we envision the use of the cooperative biofuel cell for energy conversion and management of organic compounds.

Ruthenium(II)-Catalyzed C-H (Hetero)Arylation of Alkenylic 1,n-Diazines (n = 2, 3, and 4): Scope, Mechanism, and Application in Tandem Hydrogenations.

A general ruthenium(II)-catalyzed methodology enabling the (hetero)arylation of alkenylic C-H bonds utilizing a series of synthetically appealing diazines as directing groups is presented. Despite the presence of additional nitrogen lone pairs remote from the C-H bond activation site, which could eventually poison the catalyst, the reaction times are short (3 h), thus being suitable for selective double C-H bond arylation. Mixtures of E:Z isomeric products were observed in some cases, which were further hydrogenated in a tandem manner in the presence of the remaining ruthenium catalyst from the first step, representing an alternative approach to more difficult C(sp3)-H bond functionalization. According to mechanistic studies, the unexpected E:Z product formation seems to occur by thermal C═C bond isomerization after the reductive elimination step.

Dual Chemodrug-Loaded Single-Walled Carbon Nanohorns for Multimodal Imaging-Guided Chemo-Photothermal Therapy of Tumors and Lung Metastases.

Tumor combination therapy using nano formulations with multimodal synergistic therapeutic effects shows great potential for complete ablation of tumors. However, targeting tumor metastases with nano structures is a major obstacle for therapy. Therefore, developing a combination therapy system able to target both primary tumors and their metastases at distant sites with synergistic therapy is desirable for the complete eradication of tumors. To this end, a dual chemodrug-loaded theranostic system based on single walled carbon nanohorns (SWNHs) is developed for targeting both primary breast tumors and their lung metastases.Methods: SWNHs were first modified simultaneously with poly (maleic anhydride-alt-1-octadecene) (C18PMH) and methoxypolyethyleneglycol-b-poly-D, L-lactide (mPEG-PLA) via hydrophobic-hydrophobic interactions and π-π stacking. Then cisplatin and doxorubicin (DOX) (2.9:1 molar ratio) were sequentially loaded onto the modified nanohorns in a noninterfering way. After careful examinations of the release profiles of the loaded drugs and the photothermal performance of the dual chemodrug-loaded SWNHs, termed SWNHs/C18PMH/mPEG-PLA-DOX-Pt, the dual drug chemotherapeutic and chemo-photothermal synergetic therapeutic effects on tumor cells were evaluated. Subsequently, the in vivo behavior and tumor accumulation of the drug-loaded SWNHs were studied by photoacoustic imaging (PAI). For chemo-photothermal therapy of tumors, 4T1 tumor bearing mice were intravenously injected with SWNHs/C18PMH/mPEG-PLA-DOX-Pt at a dose of 10 mg/kg b.w. (in SWNHs) and tumors were illuminated by an 808 nm laser (1W/cm2 for 5 min) 24 h post-injection.Results: DOX and cisplatin were loaded onto the modified SWNHs with high efficiency (44 wt% and 66 wt%, respectively) and released in a pH-sensitive, tandem and sustainable manner. The SWNHs/C18PMH/mPEG-PLA-DOX-Pt had a hydrodynamic diameter of 182 ± 3.2 nm, were highly stable in physiological environment, and had both dual drug chemotherapeutic (CI = 0.439) and chemo-photothermal synergistic antitumor effects (CI = 0.396) in vitro. Moreover, the dual drug-loaded SWNHs had a long blood half-life (10.9 h) and could address both the primary breast tumors and their lung metastases after intravenous administration. Consequently, chemo-photothermal combination therapy ablated the primary tumors and simultaneously eradicated the metastatic lung nodules.Conclusion: Our study demonstrates that SWNHs/C18PMH/mPEG-PLA-DOX-Pt is highly potent for chemo-photothermal combination therapy of primary tumors and cocktail chemotherapy of their metastases at a distant site.

Palladium-catalyzed selective synthesis of 3,4-dihydroquinazolines from electron-rich arylamines, electron-poor arylamines and glyoxalates.

A simple palladium-catalyzed selective synthesis of structurally diverse 3,4-dihydroquinazolines from electron-rich arylamines, electron-poor arylamines and glyoxalates has been developed under mild conditions. This reaction is carried out in a tandem manner constituted by the condensation of arylamines and glyoxalates, the selective Diels-Alder cycloaddition and oxidation processes, in which 4-nitrothiophenol was used as the key ligand.

Visible‐Light‐Promoted Arylation Reactions Photocatalyzed by Bismuth(III) Oxide

Bismuth(III) oxide has been successfully applied as a photocatalyst in the arylation of heteroarenes with diazonium salts. With a low catalyst loading (1 to 5 mol‐%), this cheap and nontoxic semiconductor could efficiently promote the formation of the aryl radical under visible light irradiation. The arylated products are obtained in moderate to good yields, and the process admits straightforward scale‐up (10 mmol; 1 mol‐% Bi2O3). In two cases, the diazonium salt was generated in situ and used in the photocatalytic arylation in a tandem manner. Besides heteroarenes, Bi2O3 also catalyzed the arylation of differently substituted alkenes and alkynes, thus representing a viable and practical alternative to the more commonly used ruthenium complexes and organic dyes.

Copper catalyzed synthesis of benzoxazoles and benzothiazoles via tandem manner

A useful protocol for the preparation of substituted 2-aminobenzoxazoles and 2-aminobenzothiazoles was presented. Under the catalysis of copper, 2-aminophenols or 2-aminothiophenols reacted with thiocarbamoyl chlorides via a tandem manner, furnishing a series of 17 benzoheterocycles smoothly with good to excellent yields (70–91%). The broad substrate scope, short reaction time, mild react conditions, easy performance and nice yields make this approach attractive, showing its practical synthetic value for the preparation of some biologically or pharmaceutically active compounds.

Experimental investigation on flow and scour characteristics around tandem piers in sandy channel with downward seepage

Experimental investigations have been carried out to study morpho-hydraulic characteristics such as scour geometry and turbulent flow properties around tandem piers in alluvial channels. Experiments were carried out in a plane sand bed with two circular piers of same diameter arranged in tandem manner under no seepage, 10% seepage and 20% seepage conditions. Downward seepage minimizes the scour depth around piers and restrains the development of scour depth with time. Strong reversal flow is found near the bed at upstream of piers and near free surface at downstream of piers where velocity and Reynolds shear stress are found to be negative which reduce in magnitude with downward seepage. The flow is more critical within the gap between two piers where velocity is lesser near free surface and gradually increasing towards bed. Quadrant analysis shows that contribution of each event to the total Reynolds shear stress increases with downward seepage. Sedimentation effect prevails within the scour hole whereas outside the scour hole erosive forces become more dominant. Reduced reversal flow at upstream of pier because of downward seepage results in decreasing higher order moments and turbulent kinetic energy. At downstream of piers, secondary currents are dominant due to wake vortices. Strouhal number decreases in case of seepage runs than no seepage condition.

Duplication-Correcting Codes for Data Storage in the DNA of Living Organisms

The ability to store data in the DNA of a living organism has applications in a variety of areas including synthetic biology and watermarking of patented genetically modified organisms. Data stored in this medium are subject to errors arising from various mutations, such as point mutations, indels, and tandem duplication, which need to be corrected to maintain data integrity. In this paper, we provide error-correcting codes for errors caused by tandem duplications, which create a copy of a block of the sequence and insert it in a tandem manner, i.e., next to the original. In particular, we present two families of codes for correcting errors due to tandem duplications of a fixed length: the first family can correct any number of errors, while the second corrects a bounded number of errors. We also study codes for correcting tandem duplications of length up to a given constant k, where we are primarily focused on the cases of k = 2,3. Finally, we provide a full classification of the sets of lengths allowed in tandem duplication that result in a unique root for all sequences.

Transition-Metal-Free One-Pot Tandem Synthesis of 4-Quinolone and 4H-Thiochromen-4-one Derivatives Through Sequential Nucleophilic Addition–Elimination–SNAr Reaction

4-Quinolone and 4H-thiochromen-4-one derivatives are readily synthesized in a tandem one-pot manner in good to excellent yields. Starting from (Z)-β-chlorovinyl ketones, an intermolecular nucleo­philic addition of amines or sodium hydrogen sulfide to (Z)-β-chloro­vinyl ketones was followed by elimination of chlorine anion to give Z-enamine or thioenol intermediates, which can be transformed to 4-quinolone or 4H-thiochromen-4-one products through intramolecular SNAr reaction, respectively.

A Spatially Separated Organic–Inorganic Hybrid Photoelectrochemical Cell for Unassisted Overall Water Splitting

The Z-scheme overall solar water splitting is a mimic of natural photosynthesis to convert solar energy into chemical fuels. Despite much effort, the available Z-scheme artificial systems are still rare, and most of them rely on inorganic semiconductors. In this study, inspired by the characteristics of p-type and higher unoccupied molecular orbital level of organic semiconductors, a spatially separated organic–inorganic hybrid Z-schematic photoelectrochemical (PEC) cell for unassisted overall water splitting is developed by wiring inorganic ZnO nanorod arrays photoanode and organic poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid (P3HT:PCBM) photocathode in a tandem manner. In the short-circuit configuration, the photocurrent density reaches an initial value of ∼78 μA cm–2 and an average value of ∼95 μA cm–2 under continuous UV–vis light irradiation, giving rise to the solar-to-fuel conversion efficiency of ∼0.12%. The average gas evolution rates are 1.59 μmol h–1 for H2 and 0.75 μmol h–1 for O2 unde...