MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performance

MgO-based adsorbents for CO2 adsorption: Influence of structural and textural properties on the CO2 adsorption performanceA series ofMgO-based adsorbents were prepared through solution–combustion synthesis and ball-milling process. The prepared MgO-based powders were characterized using X-ray diffraction, scanning electron microscopy, N2 physisorptionmeasurements, and employed as potential adsorbents for CO2 adsorption. The influence of structural and textural properties of these adsorbents over the CO2 adsorption behaviour was also investigated. The results showed that MgO-based products prepared by solution–combustion and ball-milling processes, were highly porous, fluffy, nanocrystalline structures in nature, which are unique physico-chemical properties that significantly contribute to enhance their CO2 adsorption. It was found that the MgO synthesized by solution combustion process, using a molar ratio of urea to magnesium nitrate (2:1), and treated by ball-milling during 2.5 hr (MgO-BM2.5h), exhibited the maximum CO2adsorption capacity of 1.611 mmol/g at 25°C and 1 atm, mainly via chemisorption. The CO2 adsorption behaviour on the MgO-based adsorbents was correlated to their improved specific surface area, total pore volume, pore size distribution and crystallinity. The reusability of synthesized MgO-BM2.5h was confirmed by five consecutive CO2 adsorption–desorption times, without any significant loss of performance, that supports the potential of MgO-based adsorbent. The results confirmed that the special features of MgO prepared by solution–combustion and treated by ball-milling during 2.5 hr are favorable to be used as effective MgO-based adsorbent in post-combustion CO2 capture technologies

Dinuclear Co(II)‑Muconate Complex Displaying Distorted‑TrigonalPrismatic Geometry, 2D Supramolecular Array and Weak Antiferromagnetism

Influence of the 2D supramolecular array in the distorted trigonal prismatic geometry of a dinuclear Co(II)-muconate complex exhibiting weak antiferromagnetic exchange.Dinuclear complex [ Co2(H2O)4(dmb)2(muc)][muc] (1) (muc = muconate; dmb = 5,5′-dimethyl-2,2′-bipyridine), was obtained by self-assembly solution reaction, under ambient conditions, and it was structurally characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. The complex 1 crystallizes in the monoclinic system in the C2/c space group. Noticeably, the six-coordinated Co(II) centers display a distorted-trigonal prismatic configuration. This uncommon coordination geometry is attained due to the hydrogen bonding interactions of the crystalline structure of 1, yielding thus a 2D supramolecular array. Magnetic properties measurements reveal that metaprism 1 exhibits weak antiferromagnetic ordering with θ(C-W) = -14.4 K and an E2 = 0.032 cm− 1 accordingly to Curie–Weiss model and Rueff phenomenological approach, respectively.Universidad Autónoma del Estado de México Universidad Nacional Autónoma de Méxic

Five decades of cuprizone, an updated model to replicate demyelinating diseases

Abstract: Introduction: Demyelinating diseases of the central nervous system (CNS) comprise a group of neurological disorders characterized by progressive (and eventually irreversible) loss of oligodendrocytes and myelin sheaths in the white matter tracts. Some of myelin disorders include: Multiple sclerosis, Guillain-Barré syndrome, peripheral nerve polyneuropathy and others. To date, the etiology of these disorders is not well known and no effective treatments are currently available against them. Therefore, further research is needed to gain a better understand and treat these patients. To accomplish this goal, it is necessary to have appropriate animal models that closely resemble the pathophysiology and clinical signs of these diseases. Herein, we describe the model of toxic demyelination induced by cuprizone (CPZ), a copper chelator that reduces the cytochrome and monoamine oxidase activity into the brain, produces mitochondrial stress and triggers the local immune response. These biochemical and cellular responses ultimately result in selective loss of oligodendrocytes and microglia accumulation, which conveys to extensive areas of demyelination and gliosis in corpus callosum, superior cerebellar peduncles and cerebral cortex. Remarkably, some aspects of the histological pattern induced by CPZ are similar to those found in multiple sclerosis. CPZ exposure provokes behavioral changes, impairs motor skills and affects mood as that observed in several demyelinating diseases. Upon CPZ removal, the pathological and histological changes gradually revert. Therefore, some authors have postulated that the CPZ model allows to partially mimic the disease relapses observed in some demyelinating diseases. Conclusion: for five decades, the model of CPZ-induced demyelination is a good experimental approach to study demyelinating diseases that has maintained its validity, and is a suitable pharmacological model for reproducing some key features of demyelinating diseases, including multiple sclerosis.UAEME

Syntheses and Crystal Structures of Mn(II), Ni(II) and Cu(II) Coordination Compounds Assembled by Maleato and Dimethyl-2,2′-bipyridines

We have reported the synthesis and crystalline molecular and supramolecular structures of three novel complexes of Mn(II), Ni(II) and Cu(II), 1–3, respectively, employing maleato and dimethyl-2,2′-bipyridines as ligands. 1 is a 1D polymer, where the Mn centers are six-coordinated in a distorted octahedral geometry. 2 is a dinuclear complex, generated by supramolecular interactions, where Ni ions are six-coordinated in a distorted octahedral geometry. 3 is a dinuclear complex with five-coordinated Cu ions having a slightly-distorted square pyramidal geometry. Furthermore, solid-state assemblies on the structures of 1–3 generate supramolecular frameworks, mainly through hydrogen bonding: 2D for complexes 1 and 2, and 3D for complex 3. Thus, the versatility in the different coordination modes of maleato ligand: chelate bidentate and bridging- monodentate for polymer 1, monodentate for complex 2 and chelate bidentate for complex 3; has been evidenced by generating divergent coordination compounds of three different transition metals using facile self-assembly reactionsThree complexes: {[Mn(H2O)(mal)(5dmb)·H2O}n] (1); [ Ni2(H2O)6(mal)2(4dmb)2]·3H2O (2); [ Cu2(mal)2(4dmb)2]·3H2O (3); where mal = maleato, 4dmb = 4,4′-dimethyl-2,2′-bipyridine, and 5dmb = 5,5′-dimethyl-2,2′-bipyridine; have been synthesized, using self-assembly solution reactions at ambient conditions. Crystallographic studies show that 1 crystallizes in an orthorhombic system, space group Pna21, with a = 17.4067(4) Å, b = 11.9672(2) Å, c = 8.2075(2) Å; V = 1709.70(6) Å3. Complex 2 has a monoclinic system, space group C2/c, with a = 21.206(8) Å, b = 7.523(3) Å, c = 25.399(10) Å; β = 109.755(8)°; V = 3813(2) Å3. Complex 3 crystallizes in a monoclinic system, space group C2/c, with a = 14.6976(12) Å, b = 11.3849(10) Å, c = 22.1638(18) Å; β = 101.2998(17)°; V = 3636.8(5) Å3. Complex 1 is a one-dimensional (1D) polymer, where the Mn centers are six-coordinated in a distorted octahedral geometry. 2 is a dinuclear complex, generated by supramolecular interactions, where Ni ions are six-coordinated in a distorted octahedral geometry. 3 is a dinuclear complex with five-coordinated Cu ions having a distorted square pyramidal geometry. All three complexes exhibit hydrogen bonding interactions, which generate 2D supramolecular structures in 1 and 2, whereas in complex 3 a 3D supramolecular array is formed. These novel complexes prove that the self-assembly of a dicarboxylate ligand (mal) with three different first-row transition metals, can afford coordination compounds with diverse structural characteristics and dimensionality, which can be attributed to the different ligand coordination modes and the coordination properties of the employed metals

Prevención de la desmineralización dental por uso de aparatología ortodóntica fija y su remineralización

El fenómeno de la desmineralización-remineralización es un ciclo continuo pero variable, que se repite con la ingesta de los alimentos; específicamente los carbohidratos, que al metabolizarse en la placa dental, forman ácidos que reaccionan en la superficie del esmalte, la cual cede iones de calcio y fosfato y altera la estructura cristalina de la hidroxiapatita, tornándola más susceptible a ser remineralizada. Si no continúa la producción de ácidos después de 30 a 45 minutos, el pH sube y los minerales en forma iónica tienden a incorporarse a la estructura dentaria (Monterde, 2002). La lesión de mancha blanca es la primera expresión clínica de la desmineralización, que ocurre sobre la superficie del esmalte, como resultado de alteraciones sucesivas del pH (Livias et al., 2008). La formación de lesiones de mancha blanca durante el tratamiento de ortodoncia, se han asociado con la acumulación prolongada de placa bacteriana en las superficies del esmalte adyacentes a la aparatología fija, pues es un hecho que la remoción de la misma es muy complicada y es seguida de la producción de ácido y pérdida de la sustancia calcificada del diente (Livias et al., 2008). Las características que alteran la superficie del diente pueden presentarse como un problema estético incluso más de 5 años después del tratamiento (Castellanos et al., 2013)

Novel tuffite/Fe-Cu oxides nanocomposite with functionality for dye removal in aqueous solution

Fe-Cu oxides nanoparticles were embedded on tuffite (TUF) mineral by means of a simple immersion-ion impregnation, followed by a reduction reaction, methodology. TUF/Fe-Cu nanocomposite characteristics were investigated by XRD, TEM, BET, SEM, FT-IR spectroscopy and pHzpc method. Fe-Cu nanostructures with mean sizes between 10 and 20 nm were effectively supported on TUF. Because of its functional properties, the nanocomposite was studied as adsorbent material for the degradation of Malachite Green (MG) organic dye in aqueous solution. The adsorption kinetic data was well-fitted to pseudo first-order model, indicating physisorption as the main mechanism of adsorption. High pH and temperature of the solution favored malachite green adsorption. The adsorption process was spontaneous and endothermic. In comparative sorption experiments with different dyes, the nanocomposite showed better removal capacities for cationic and basic than for anionic and acid dyes. Langmuir, Freundlich, Langmuir-Freundlich and Temkin models were applied to evaluate the isotherms, resulting in an adsorption capacity of 376.66 mg/g, which is above most of the adsorbent materials so far employed for malachite green degradation in aqueous solution. Therefore, this novel, easy to prepare and low-cost nanocomposite proved to have synergic functionality as an efficient adsorbent material for cationic organic dyes.UAEM/2708/2013 and 3688/2014/CIB projects. Scholar-ship Grant No. 289993CONACYT

Antibacterial Effect of Silver Nanoparticles Versus Chlorhexidine Against Streptococcus mutans and Lactobacillus casei

The porpoise of the study was to evaluate the antibacterial effect of silver nanoparticles (Ag-NPs) versus chlorhexidine (CHX) against Streptococcus mutans and Lactobacillus casei. Three different reducing agents were used for the synthesis and characterization of Ag-NPs: sodium borohydride (NaBH4), a chemical method, and Heterotheca inuloides (Hi) and Camellia sinensis (Cs), two eco-friendly methods. The synthesized substance was deposited on deciduous teeth. Its behavior in dental tissues was evaluated through an energy dispersive X-ray spectroscopy (EDS) analysis, using a scanning electron microscope (SEM). The characterization of Ag-NPs in terms of shape, size, and polydispersity was performed through spectrophotometry of ultraviolet-visible light analysis (UV-vis), as well as by transmission electron microscopy. Isolation and culture of strains S. mutans and L. casei were done to perform the microbiological analysis

Antimicrobial effect of silk and catgut suture threads coated with biogenic silver nanoparticles

Abstract Two bionanocomposites based on suture threads, silk-silver nanoparticles (Ag NPs) and catgut-Ag NPs, were prepared through a green chemistry methodology using Chenopodium ambrosioides (Mexican Epazote) as reducing agent. UV-Vis spectrophotometry (UV-Vis), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM), were used for their characterization. UV-Vis confirmed the synthesis of silver nanoparticles. Micrographs showed polydisperse, mostly spherical, Ag NPs attached to both suture threads. The bionanocomposites antimicrobial properties were evaluated through cultures and inhibition zones tests. The Chenopodium ambrosioides- assisted synthesized bionanocomposites have proved antibacterial effect against S. aureus and E. coli in both sutures (silk and catgut) and could be potentially useful for oral or periodontal surgery. There was no significant difference statistically in inhibition of Staphylococcus aureus versus Escherichia coli

Silver nanoparticles in orthodontics, a new alternative in bacterial inhibition: in vitro study

Background The purpose of the study is to assess the antiadherent and antibacterial properties of surface-modified different orthodontic brackets with silver nanoparticles against Streptococcus mutans and Streptococcus sobrinus, using radiomarker. Methods In this study evaluated quantitatively the adherence of Streptococci to orthodontic brackets, 300 samples of orthodontic brackets were selected and classified in to 10 groups as follow: GIn (InVu-Roth), GIIn (System-AlexanderLTS), GIIIn (Gemini-Roth), GIVn (NuEdge-Roth), GVn (Radiance plus-Roth), GVI (InVu-Roth), GVII (System-AlexanderLTS), GVIII (Gemini-Roth), GIX (NuEdge-Roth), GX (Radiance plus-Roth). All the samples were sonicated and Streptococci were cultivated by gender. A radioactive marker (3H) was used to codify the bacteria and measure them. After that, the brackets were submerged in a radiolabelled solution, and the radiation was measured. The statistical analysis was calculated with ANOVA test (Sheffè post hoc). Results The results showed significant differences were found among the groups. GIIIn shown the lowest scores for both bacteria; in contrast, GIX for Streptococcus mutans and GVI for Streptococcus sobrinus were the highest values. Conclusions Surface modification of orthodontic brackets with silver nanoparticles can be used to prevent the accumulation of dental plaque and the development of dental caries during orthodontic treatment

EGF-Coupled Gold Nanoparticles Increase the Expression of CNPase and the Myelin-Associated Proteins MAG, MOG, and MBP in the Septal Nucleus Demyelinated by Cuprizone

ARTICULO DE ACCESO ABIERTOCurrent pharmacological therapies against demyelinating diseases are not quite satisfactory to promote remyelination. Epidermal growth factor (EGF) can expand the population of oligodendrocyte precursor cells (OPCs) that may help with the remyelination process, but its delivery into the injured tissue is still a biomedical challenge. Gold nanoparticles (GNPs) may be a useful tool for drug delivery into the brain. To evaluate remyelination in the septal nucleus, we administered intracerebral GNPs coupled with EGF (EGF–GNPs). C57BL6/J mice were demyelinated with 0.4% cuprizone (CPZ) and divided into several groups: Sham, Ctrl, GNPs, EGF, and EGF–GNPs. We evaluated the remyelination process at two time-points: 2 weeks and 3 weeks post-injection (WPI) of each treatment. We used the rotarod for evaluating motor coordination. Then, we did a Western blot analysis myelin-associated proteins: CNPase, MAG, MOG, and MBP. EGF–GNPs increase the expression of CNPase, MAG, and MOG at 2 WPI. At 3 WPI, we found that the EGF–GNPs treatment improves motor coordination and increases MAG, MOG, and MBP. EGF–GNPs enhance the expression of myelin-associated proteins and improve the motor coordination in mice. Thus, EGF-associated GNPs may be a promising pharmacological vehicle for delivering long-lasting drugs into the brain.S/