Abstract Corrosion inhibition action of CGS, namely, PPAB, HPAB, DDPAB and HDPAB, on MS in 1 N HCl, has been investigated. The compounds were synthesized in laboratory, and their influence on MS corrosion inhibition was investigated by WL, PDP and EIS techniques. Ea and ΔGads values of all compounds were calculated, in order to investigate the corrosion inhibition mechanism. The studies revealed that all the compounds inhibited MS corrosion by blocking its active sites. The inhibitors adsorption onto the MS surface in HCl was found to obey the Langmuir’s isotherm. CGS IE(%) was found to vary with their nature and C, and the HCl T, IT and C. Maximum IE(%) was 99.7%, for HDPAB (250 ppm), which had the lowest CR, i.e. 0.15 mmy-1.

Abstract: This study evaluates the performance of large language models, specifically GPT-3.5 and BARD (supported by Gemini Pro model), in un-dergraduate admissions exams proposed by the National Polytechnic Institute in Mexico. The exams cover Engineering/Mathematical and Physical Sciences, Biological and Medical Sciences, and Social and Administrative Sciences. Both models demonstrated proficiency, exceeding the minimum acceptance scores for respective academic programs to up to 75% for some academic programs. GPT-3.5 outperformed BARD in Mathematics and Physics, while BARD performed better in History and questions related to factual information. Overall, GPT-3.5 marginally surpassed BARD with scores of 60.94% and 60.42%, respectively.

ABSTRACT Oil is a non-renewable resource, and it is essential to improve oil recovery. Surfactant flooding is a key technology in enhancing oil recovery. The present work aims to develop a new surfactant to the combination flooding system in oil displacement. The Aminosulfonic Acid Gemini Surfactant was prepared by using Hexadecylamine, 1-Butanaminium,N,N,N-tributyl-,bromide (1:1) and Sodium 2-chloroethyl sulfonate. The AminoSulfonic Acid Gemini Surfactant Sodium N,N’-Dihexadecyl-2-propanol- 1,3-ethylsulfonate SNNDPE) has better reaction temperature at 80℃. The best reaction time of SNNDPE is 12 h. Next, We made a characterization of SNNDPE. A new gemini surfactant was developed, which is beneficial to the research of material science. Then the performance of the new Gemini surfactant was tested. The surface tension tests suggested that the newly synthesized Aminosulfonic Acid Gemini Surfactant has higher surface activity. The resistance temperature of the Aminosulfonic Acid Gemini Surfactant solution is 80℃. Moreover, the oil-water interfacial tension experiment suggested that the minimum aqueous solution of the combination flooding system reaches an ultra-low level of 9.4 × 10−4 mN/m. The combination flooding system experiment results can be considered as a guidance in the design and studies of the combination flooding system for a selective.

A reversed-phase high performance liquid chromatography (RP-HPLC) method with ultraviolet detection was developed and validated for the simultaneous quantification of antiretroviral drugs lamivudine (3TC), stavudine (d4T), and zidovudine (AZT) in perfusate samples obtained from the Single-Pass Intestinal Perfusion studies. The chromatographic analysis was performed using a Gemini C18 column and didanosine as internal standard (IS). The following parameters were considered for the validation procedure: system suitability, accuracy, precision, linearity and selectivity. The limits of detection were 0.32 µg/mL for 3TC, 0.11 µg/mL for d4T and 0.45 µg/mL for AZT and the limits of quantification were 1.06 µg/mL for 3TC, 0.38 µg/mL for d4T and 1.51 µg/mL for AZT. Repeatability and intermediate precision ranged from 1.05 to 1.31 and 1.50 to 1.87, respectively, and are expressed as percent of relative standard deviation (RSD). Based on these results, the developed and validated RP-HPLC method can be used for simultaneous determination of 3TC, d4T, and AZT in perfusate samples. Furthermore, this method is simple and adequate for measurements of the antiretroviral drugs in the same sample, since those compounds are mostly co-administered. Besides, this work can be used as an initial base for the development of similar methods in the same conditions presented in our study.

Resumen En la actualidad hay diferentes formas de abordar la maloclusión de clase III, todas las formas tienen como objetivo principal solucionar la maloclusión y están encaminadas a diagnosticar y llevar al paciente a una oclusión es table, estética y sobretodo sin daño alguno a los tejidos que conforman el sistema estomatognático. Se muestra en este artículo el manejo de la ma loclusión de clase III con arcos de Multiloop Edgewise Arch Wire (MEAW) como una opción rápida, estable y de excelentes resultados para la solu ción de este tipo de discrepancias. La maloclusión de clase III puede ser tra tada de diferentes formas como el tratamiento temprano, la compensación dental, el camuflaje esquelético y la opción quirúrgica. La compensación dental puede ser de diferentes formas, como por ejemplo: exodoncias de premolares inferiores, torque inferior negativo y positivo superior, con ayuda de anclaje esquelético (mini tornillos) y muchas más que no se enuncian. En los casos que se involucra el perfil o la simetría facial y su origen es de características de ADF (Anomalía Dentocranéo Maxilofacial) requirieran de cirugía ortognatica para su solución, puesto que es de origen esquelético y debido a severidad es no compensable. Este articulo muestra un manejo diferente como opción de compensación de maloclusión de clase III. Es un reporte de caso clínico de un paciente del Posgrado de Ortodoncia de la Universidad Antonio Nariño de la clínica de arco recto manejado con brac kets de prescripción MBT Gemini Unitek 3M slot 0.022”x0.025” los cua les se les coloca arcos de Multiloop Edgewise Arch Wire (MEAW) después de ocho meses de tratamiento, cuatro meses en alineación y nivelación y cuatro meses del uso arcos de Multiloop Edgewise Arch Wire (MEAW) la corrección dentoalveolar se corrige gracias a la retracción canina y molar de 6mm bilateral haciendo rotar el plano de oclusión según la filosofía del tratamiento de Multiloop Edgewise Arch Wire (MEAW) obteniendo las seis llaves de la oclusión de Andrews.

Abstract At present, there are different ways of approaching Class III malocclusion, all of which have the main objective of solving malocclusion and are aimed at diagnosing and bringing the patient to a stable, aesthetic occlusion and above all without any damage to the tissues that make up the Stomatognatic system. This paper deals with the handling of Class III malocclusion with Multiloop Edgewise Arch Wire (MEAW) as a fast, stable and excellent choice for solving this type of discrepancy. Class III malocclusion can be treated in different ways such as early treatment, den tal compensation, skeletal camouflage and surgical option. The dental compensation can be of different forms, as for example: extractions of lower premolars, negative inferior torque and superior positive, with the aid of skeletal anchorage (TAD) and many more that are not stated. In cases, involving facial profile or symmetry and its origin is the characteristics of ADF (Maxillofacial Dentocranial Anomaly) require orthognathic surgery for its solution, since it is of skeletal origin and due to severity is not compensable. This article shows a different management as an option for class III malocclusion compensation. It is a clinical case report of a patient of the Orthodontics Postgraduate of the Antonio Nariño University of the straight arch clinic handled with MBT Gemini Unitek 3M slot 0.022 “x0.025” brackets which are placed with Multiloop Edgewise Arch arcs Wire (MEAW) after eight months of treatment, four months in alignment and leveling, and four months of use Multiloop Edgewise Arch Wire (MEAW) correction is corrected by bilateral canine and molar retraction by rotating the plane Of occlusion according to the philosophy of the treatment of Mul tiloop Edgewise Arch Wire (MEAW) obtaining the six keys of the Andrews occlusion.

Abstract While the planet-metallicity correlation for FGK main-sequence stars hosting giant planets is well established, it is less clear for M-dwarf stars. We determine stellar parameters and metallicities for 16 M-dwarf stars, 11 of which host planets, with near-infrared spectra from the Gemini Near-Infrared Spectrograph (GNIRS). We find that M-dwarfs with planets are preferentially metal-rich compared to those without planets. This result is supported by the analysis of a larger catalogue of 18 M stars with planets and 213 M stars without known planets (Terrien et al. 2015), and demonstrates the utility of GNIRS spectra to obtain reliable stellar parameters of M stars. We also find that M dwarfs with giant planets are preferentially more metallic than those with low-mass planets, in agreement with previous results for solar-type stars. These results favor the core accretion model of planetary formation.

Resumen Mientras que la correlación planeta-metalicidad para las estrellas de secuencia principal FGK con planetas gigantes está bien establecida, los resultados no son claros para las enanas M. Se determinan parámetros estelares y metalicidades de 16 estrellas enanas M, incluyendo 11 con planetas, a partir de espectros infrarrojos de GNIRS (Gemini Near-Infrared Spectrograph). Se encuentra que las enanas M con planetas son preferentemente ricas en metales en comparación con aquellas sin planetas. Esto se confirma con el análisis de 18 estrellas M con planetas y 213 estrellas M sin planetas detectados (Terrien et al. 2015), y demuestra la utilidad de los espectros GNIRS. Las enanas M con planetas gigantes son preferentemente más metálicas que aquellas con planetas de menor masa, de acuerdo con lo reportado para estrellas de tipo solar. Estos resultados favorecen el modelo de acreción del núcleo de formación planetaria.

Abstract Cationic imidazoline surfactants have already gained much interest due to their wide range of industrial applications. In the present scenario on surfactants research, surfactants are being converted into their corresponding gemini surfactants because of their uncommon self-assembling characteristics and unique interfacial activity. Gemini surfactants are showing many times better performance properties than their conventional monomeric counterparts because of their much lesser CMC and far better ability to reduce surface tension. These extraordinary properties make them potential candidates in surfactant industries. Conventional methods used in the synthesis of gemini surfactants are suffering with few disadvantages. Long reaction duration is one of the major issues involved in the synthesis of gemini surfactants. Current research involves the microwave synthesis of C12-C18 saturated/unsaturated fatty acids based cationic gemini imidazoline surfactants in much lesser time. An effort has also been made to make them readily degradable through incorporating a carbonate linkage into their spacer moiety. Structural characterization of synthesized gemini surfactants have been achieved through 1H-NMR and FT-IR. Cheaper and easily available plant based materials and microwave assisted organic synthesis of cationic gemini imidazoline surfactants with easily degradable chemical moiety make them to be considered as novel and green surfactants.

No início dos anos sessenta, a corrida espacial entre a agência espacial americana NASA e o correspondente programa soviético envolveu a solução de diversos problemas desafiadores. Um deles era a habilidade de rendezvous (acoplamento) entre duas espaçonaves em órbita. O primeiro rendezvous foi efetuado pelos americanos na missão Gemini 8, comandada por Neil Armstrong, que posteriormente viria a ser o primeiro homem a pisar na Lua. Dentre os vários aspectos interessantes do problema do acoplamento em órbita, citamos o seguinte resultado paradoxal: considerando duas espaçonaves em uma mesma órbita próxima à Terra, se uma delas acionar seus foguetes com o intuito de aumentar a velocidade para alcançar a segunda espaçonave, acabará por ficar mais lenta. O objetivo deste artigo é analisar tais resultados, que resultam do fato de que altitude e velocidade são correlacionadas quando consideramos as equações de corpos em queda livre de acordo com as leis da gravitação.

In the early sixties, the space race between the American agency NASA and its Soviet counterpart involved the solution of several challenges. One of them was the ability of rendezvous between two orbiting spacecrafts. The Americans did the first successful rendezvous in the Gemini 8 mission commanded by Neil Armstrong, who years later would become the first man to set foot on the moon. Among the several interesting aspects of manned orbital rendezvous we cite the following paradox: considering two spacecrafts in the same near earth orbit, if one of them accelerates in order to catch up with the other, it will ultimately left behind. In this paper we analyze such counter intuitive results, which follows from the fact that altitude and velocity are correlated when we consider the equations governing free falling bodies, according Newton’s Universal Gravitational Law.

A simple, specific, accurate and precise reversed phase high pressure liquid chromatography (RP-HPLC) method has been developed for the simultaneous estimation of tramadol hydrochloride (TRA) and dicyclomine (DCY) in bulk and tablet dosage form. Chromatography was carried on Phenomex Gemini C column (4.6 x 250 mm, 5u particle size) using mixture of methanol, acetonitrile and 0.1% triethylamine (TEA) pH 3.0 (adjusted with orthophophoric acid) in the ratio of 35:5:60 (v/v/v) respectively as a mobile phase. The flow rate 1.0mL min-1 and detection wavelength 275 nm was selected for the present study. The retention time of tramadol hydrochloride and dicyclomine were 4.13 min and 9.06 min respectively. The linear regression analysis data for the calibration plots showed a good linear relationship over the concentration range of 50-300 μg mL-1 for tramadol hydrochloride and 10-60 μg mL-1 for dicyclomine. The proposed method was validated with respect to linearity, precision, accuracy, specificity and robustness. The proposed method was found to be simple, rapid, accurate, precise and reproducible. Thus it can be applied for routine quality control analysis of tramadol hydrochloride and dicyclomine in tablet dosage form.

Space foods have had great importance in the development of manned space missions since they constitute the only source of energy and nutrients for the human being outside the planet Earth. These foods have undergone a great evolution since the beginning of the Mercury Program to current missions to the International Space Station (ISS). Initially they were designed to provide a great energy and nutrient density and currently priority is given to psychological and organoleptic characteristics since they contribute to increased consumption and a better nutritional status of astronauts. The aim of the present study is to make a retrospective analysis of what has been published until today about the space food, since in the context of a possible future mission manned to deep space, available food are not currently suitable for ensuring an optimal state of health of the astronauts. To search for these items has been used database PubMed and web of the jet propulsion laboratory (Jet propulsion laboratory) National Aeronautics and Space Administration NASA articles published up to 2012.

Los alimentos espaciales han tenido una gran importancia en el desarrollo de las misiones espaciales tripuladas ya que constituyen la única fuente de energía y nutrientes para el ser humano fuera del planeta Tierra. Dichos alimentos han experimentado una gran evolución desde el inicio del Programa Mercury hasta las actuales misiones a la International Space Station (ISS). En un primer momento eran diseñados para ofrecer una gran densidad energética y nutritiva y actualmente se da prioridad a las características organolépticas y psicológicas, ya que contribuyen a un mayor consumo y un mejor estado nutricional de los astronautas. El objetivo del presente estudio es hacer un análisis retrospectivo de las publicaciones hasta la fecha sobre alimentos espaciales para ver si los disponibles actualmente son apropiados para mantener un buen estado nutricional de los astronautas en el marco de una misión espacial tripulada al espacio profundo. Para la búsqueda de estos artículos se ha utilizado la base de datos de PubMed y de la web del Jet Propulsion Laboratory de la National Aeronautics and Space Administration (NASA), de los artículos publicados hasta el año 2012.

AbstractThe aim of this work was to develop and validate an analytical method for the identification of the chemical marker of Schinopsis brasiliensis Engl., Anacardiaceae. It would determine the total polyphenols and flavonoid content by spectrophotometric methodology in the dried extract of plant. The chromatographic profiles of S. brasiliensis were determined using HPLC-UV. The liquid chromatography method was conducted on a Phenomenex Gemini NX C18 column (250 × 4.6 mm, 5 μm). The mobile phase consisted of 0.05% orthophosphoric acid: methanol. The flow rate was 1 ml/min and effluents were monitored at 271 nm. The retention time for gallic acid was 8.5 min. The described method has the advantage of being both rapid and easy. Hence it can be applied for routine quality control analysis of herbal preparation containing S. brasiliensis.

In the present study an isocratic reverse phase-high performance liquid chromatography (RP-HPLC) method was developed and validated for simultaneous estimation of dicyclomine hydrochloride (DCY) and famotidine (FAM) in bulk and pharmaceutical dosage forms. The separation was achieved on a Phenomex Gemini C column (4.6 x 250 mm, 5μ particle size) using a mixture of methanol and 0.1% triethylamine (TEA) pH 3.0 (adjusted with orthophosphoric acid) in the ratio of 40:60 (v/v) as a mobile phase. The flow rate was 1.0 mL min-1, column temperature was kept at 28 0 C and detection was monitored at 270 nm. The retention time of dicyclomine hydrochloride and famotidine was found to be 10.72 and 2.72 min respectively. Recovery studies were satisfactory and the correlation coefficient for FAM and DCY were 0.9947 and 0.9935 respectively, indicates linearity of the methods within the limits. The developed method can be used for routine quality control simultaneous analysis of DCY and FAM in tablet dosage form without any interference of excipients.

The inclusion complexes of gemini surfactants, (CnN)2C1(2) (where n = 12,14), and p-cyclodextrin (p-CD) in aqueous solutions were investigated by an isothermal titration calorimetric method and ¹H NMR spectroscopy at 293.15 K. The stability constants, stoichiometry, formation enthalpies, entropies and Gibbs energies for the complexes in aqueous solution have been derived from the calorimetric data. p-CD in aqueous (C12N)2Cl2/(C14N)2Cl2 solutions forms 2:1 mole ratio host-guest complexes. The large values of the stability constants indicate that these complexes are stable in the aqueous solutions. The negative Gibbs energy changes indicate that formation of the host-guest complexes is generally a spontaneous process. Both the formation enthalpy and formation entropy evidently decrease as the number of methylenes in each of the hydrophobic tails increase. The thermodynamic parameters are discussed in the light of the different structures of the host and guest molecules. Chemical shift data of protons in the CD molecule, induced by the formation of the complexes have been determined by ¹H NMR spectroscopy.

Gemini surfactants, butanediyl 1,4-bis(dimethyl cetylammonium bromide), pentanediyl 1,5 - bis (dimethyl cetylammonium bromide) and hexanediyl 1,6 - bis (dimethyl cetylammonium bromide) from Alkanediyl-α, ω-bis (dimethyl cetylammonium bromide) series were synthesized in laboratory and were characterized by using Nuclear Magnetic Resonance (NMR) spectroscopy. The surfactants were tested as corrosion inhibitors for mild steel in 20% formic acid. The influence of surfactants on mild steel corrosion inhibition was investigated by measuring the corrosion rate of mild steel in their absence and presence by weight loss measurements, solvent analysis of iron ions into the test solution and potentiodynamic polarization measurements. The surface morphology of the corroded steel samples in presence and absence of surfactants was evaluated by using Scanning Electron Microscopy (SEM). The synthesized gemini surfactants performed as excellent corrosion inhibitor, the inhibition efficiency (IE) being in the range of 76.66-97.41%. The IE of surfactants is slightly affected by the spacer length. The IE increased with increase in surfactant concentration and temperature. The adsorption of gemini surfactants on the steel surface was found to obey Langmuir adsorption isotherm. The results of the potentiodynamic polarization studies are consistent with the results of weight loss studies.

OBJETIVO: avaliar a fricção apresentada por braquetes autoligáveis de aço inoxidável com sistema passivo de tampa deslizante sob angulação de 0 grau e 2,5 graus, e comparar o comportamento desse grupo sob angulação nula com o de um grupo de braquetes autoligáveis com sistema ativo de tampa resiliente. MÉTODOS: foram utilizados 25 braquetes de caninos superiores, divididos em 5 grupos - braquetes autoligáveis passivos Damon SL II sob angulação de 0 grau e de 2,5 graus; braquetes convencionais Gemini amarrados com ligaduras elásticas sob as mesmas angulações; e um grupo formado pelo sistema ativo Time 2, sob angulação nula. A hipótese a ser testada é se artefatos autoligáveis com sistema de tampa passiva são mais efetivos no controle da fricção do que dispositivos contendo coberturas ativas. O tracionamento foi realizado segundo emprego de 25 segmentos de fio de aço inoxidável 0,020" na máquina de ensaios EMIC DL 10000 com célula de carga de 2,0kg. Cada conjunto braquete/fio foi responsável pela geração de quatro corpos de prova, totalizando-se 100 leituras. As comparações entre médias dos valores foram realizadas através da Análise de Variância (one-way ANOVA) com correções pelo coeficiente de Bonferroni. RESULTADOS E CONCLUSÃO: as médias de fricção encontradas confirmaram a hipótese em teste, de que o sistema de braquetes Damon SL II é mais eficiente no controle do atrito do que o sistema de tampa ativa sob angulação de 0 grau (p<0,01). Quando submetidos a angulações de 2,5 graus, a fricção aumentou significativamente (p<0,01), porém mantendo-se ainda muito inferior aos patamares evidenciados no grupo de braquetes convencionais amarrados com ligaduras elásticas.

OBJECTIVE: The aim of this study was to assess resistance to sliding of stainless steel passive self-ligating brackets with 0° and 2.5° angulations and to compare them to active self-ligating brackets at zero angulation. The hypothesis to be tested was that passive self-ligating brackets produce lower frictional forces than active self-ligating brackets. METHODS: Twenty five 0.022 x 0.028-in slot maxillary canine brackets were divided into 5 groups of 5 brackets: Damon SL II (Ormco, CA, USA) self-ligating bracket and Gemini (3M/Unitek, CA, USA) conventional bracket with angulation of 0 and 2.5° and a group of Speed 2 (American Orthodontics, WI, USA) active clip self-ligating system with zero angulation. Twenty five segments of stainless steel 0.020-in archwire (TP Orthodontics, IN, USA) were tested and each bracket/wire interface was evaluated at 4 successive points during sliding. Overall, 100 frictional values were analyzed by parametric analysis of variance and Bonferroni tests. RESULTS AND CONCLUSION: Frictional tests were performed with an Emic DL 10000 testing machine (Emic, Brazil) with a load cell of one kilogram. Passive self-ligating brackets produced lower frictional forces than active self-ligating brackets (p < 0.01). Under angulation, brackets with a slide mechanism produced higher friction than the same brackets under zero angulation (p < 0.01). Nevertheless, the slide system under angulation produced smaller friction values than conventional brackets tied with elastomeric ligatures in 0° tests.