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The present study aimed to (a) establish the frequency of consumption of red meat and eggs; (b) determine serum ferritin levels (μg/l); and (c) establish the relationship between serum ferritin and the consumption of red meat and eggs. In Colombia during 2014–2018, an analytical study was conducted in 13 243 Colombian children between the ages of 5 and 17 years, based on cross-sectional data compiled by ENSIN-2015 (Encuesta Nacional de la Situación Nutricional en Colombia-2015) on serum ferritin levels and dietary consumption based on a questionnaire of the frequency of consumption. Using simple and multiple linear regression, with the serum ferritin level as the dependent variable and the frequency of consumption as the main explanatory variable, the crude and adjusted partial regression coefficients (β) between serum ferritin levels and consumption were calculated. The frequency of habitual consumption of red meat was 0⋅49 (95 % CI 0⋅47, 0⋅51) times/d. The frequency of habitual egg consumption was 0⋅76 (95 % CI 0⋅74, 0⋅78) times per d. The mean serum ferritin level in men was 41⋅9 (95 % CI 40⋅6, 43⋅1) μg/l and in women, 35⋅7 (95 % CI 34⋅3, 37⋅7) μg/l (P < 0⋅0001). The adjusted β between the consumption of red meat and eggs and serum ferritin levels were β = 3⋅0 (95 % CI 1⋅2, 4⋅7) and β = 2⋅5 (95 % CI 1⋅0, 3⋅9) for red meat and eggs, respectively. In conclusion, red meat and eggs are determinants of serum ferritin levels in Colombia and, therefore, could be considered public policy options to reduce anaemia and Fe deficiency.
Age-related hearing loss (ARHL) is a sensory impairment, with a dramatic increase in its incidence, which is caused by genetic and environmental factors such as noise and ototoxic drugs. Recent studies correlated ARHL to elevated plasma homocysteine (Hcy) by folate deficiency, suggesting that reduction of Hcy levels by folate supplementation could potentially ameliorate ARHL.
Hyperhomocysteinemia (HHcy), a status that contributes to ARHL, may also arise from malfunction of Hcy remethylation by betaine homocysteine S-methyltransferases (BHMTs) and methionine synthase in the methionine cycle. The expression and/or activity of these enzymes may be altered by ototoxic drugs, including paracetamol (APAP).
To determine the effect of APAP in cochlear morphology and function of control and Bhmt-/- mice, and to analyze putative preventive effects of folic acid (FA) supplementation.
Materials and Methods
Two-month-old Bhmt-/- mice (n = 47), with greater dependence on folate metabolism for Hcy remethylation, and Bhmt + / + mice (n = 42) were fed control or FA supplemented diets for 30 days. The last day APAP (250 mg/kg) or placebo were injected intraperitoneally.
Hearing was evaluated by recording auditory brainstem responses (ABR) at the beginning of the experiment and after treatments. Picrosirius red staining was used for evaluation of the cochlear lateral wall cytoarchitecture. Plasma and hepatic metabolite levels were determined by HPLC or on Spinlab 100® autoanalyzer.
Loss of Bhmt expression induced HHcy, but an impact on hearing acuity was not observed. Acute APAP administration did not induce ABR threshold shifts. However, following ototoxic treatment, changes of 5–17% in the areas of the stria vascularis and spiral ligament were detected between Bhmt-/- mice under different dietary treatments; cochlear structures of Bhmt-/- mice receiving APAP plus FA supplementation resemble those of the control group. APAP increases susceptibility to ototoxic damage in the presence of HHcy.
BHMT plays a central role in cochlear methionine metabolism. FA supplementation modulates Hcy levels, contributing to a proper remethylation status that prevents ARHL.
The glycaemic index (GI) and glycaemic load (GL) are involved in the aetiology of different diseases, and they could be related to the development of colorectal cancer (CRC). The aim of this study was to evaluate the association between the quality and quantity indicators of carbohydrates consumed by the population of Córdoba (Argentina) and the odds of developing CRC in 2008–2016 period. A case–control study was conducted with 492 participants (161/331 cases/controls), interviewed through a validated FFQ. Multilevel logistic regression models were used to assess the effect of GI, GL and the quantity or weekly intake of high-GI foods on CRC occurrence, following adjustment for individual/first-level covariates, and using level of urbanisation as the contextual variable. The models were stratified by sex. Participants in the highest v. lowest tertile of dietary GL and weekly intake of high-GI foods had increased odds of CRC presence in the entire sample (OR 1·64, 95 % CI 1·16, 2·34 and OR 1·11, 95 % CI 1·09, 1·14, respectively) and in women (OR 1·98, 95 % CI 1·24, 3·18 and OR 1·41, 95 % CI 1·09, 1·83, respectively). In men, the second tertile of GL and weekly intake of high-GI foods were associated with CRC (OR 1·44, 95 % CI 1·04, 1·99 and OR 1·48, 95 % CI 1·32, 1·65, respectively). Also, GI was associated with CRC in women (highest v. lowest tertile OR 2·12, 95 % CI 1·38, 3·27). In addition to the quantity and quality of carbohydrates intake, it is important to consider the frequency of consumption of high-GI foods in CRC prevention.
The language learning potential of writing has been an underresearched topic in the English as a foreign language (EFL) context. The present study investigates what Basque-Spanish EFL teenage learners (n = 60) notice when writing a composition in response to visual stimuli in a three-stage writing task including output, comparison, and delayed revision. The present study also explores how this noticing and feedback processing affects their subsequent revisions. The findings revealed that participants noticed mainly lexical problems, although they also paid attention to content features. Moreover, more proficient learners and guided learners noticed more features. A qualitative analysis of the results indicated that, overall, learners had a negative attitude toward writing and modeling, but those with more positive beliefs incorporated more items in subsequent revisions. A number of implications for research and pedagogy will be discussed.
The design of nanostructured materials based on natural components, such as clay minerals, offers new solutions to biomedical challenges such as more efficient and storage-stable vaccines. Clay-lipid hybrid materials have proved useful as adjuvants in influenza vaccines and with a possible projection to leishmaniasis vaccines and other pathogens. Self-assembly of phospholipid molecules on the surface of microfibrous sepiolite and lamellar Mg/Al layered double hydroxide renders a biocompatible lipid bilayer membrane that ensures non-degrading immobilization of proteins and other biological species including viral particles and DNA (deoxyribonucleic acid). Immunization tests in mice showed the superior immunogenicity of a clay-lipid-supported virus compared to a commercial aluminium hydroxide adjuvant.
Polypeptides are receiving increasing attention as building blocks to create nanostructures for biomedical applications. The first goal of this investigation was to explore the influence of the reaction conditions in the synthesis of well-defined dendritic graft (arborescent) polypeptides from amine-terminated poly(γ-benzyl L-glutamate) (PBG) chains. The optimization was carried out in terms of the reaction temperature, solvent, reaction time, and mole ratio of reactants and coupling agents. Size exclusion chromatography served to evaluate the grafting reaction in terms of grafting yield (fraction of side chains coupled with the substrate) and coupling efficiency (fraction of coupling sites consumed on the substrate). The maximum grafting yield and coupling efficiency achieved were 67% and 74%, respectively. These arborescent PBG substrates were subsequently grafted with poly(ethylene oxide) segments forming a hydrophilic shell, to obtain water-dispersible unimolecular micelles useful as delivery vehicles for doxorubicin.
Non-planar iodinated pyrrole structures were found through DFT calculations of geometry optimization, when doping one pyrrole molecule with iodine atoms. This take us to a new mono-iodinated pyrrole structure in which one pyrrole molecule is attacked with one iodine atom in a pyramidal configuration. Then, the pyrrole molecule was attacked with two and until four optimized linear iodine atoms in a pyramidal structure configuration. The corresponding potential energy curves were also constructed in order to know what kind of adsorption (physisorption or chemisorption) is obtained, considering physisorption as lower than ten kcal/mol, and chemisorption greater than twenty kcal/mol according to the literature. Finally, it is known that halogenated pyrrole is a highly conductive material required in several fields.
Cardiovascular diseases, frequently associated to the formation of aneurisms, are the mayor cause of mortality and morbidity in the world. Due to the increased need for the regeneration of arteries and veins, several natural and synthetic biopolymers such as poly(glycerol sebacate), PGS, have been studied to make blood vessel constructs. PGS elastomeric properties develop after it is crosslinked; however, the poor solubility of the material limits the process to fabricate useful constructs for tissue engineering by electrospinning, casting, or other methods. The structure and properties of electrospun scaffolds made from soluble poly(glycerol sebacate) and poly(ε- caprolactone), are reported here. Soluble PGS oligomers (o-PGS) of different molecular weight, obtained by the polycondensation reaction of sebacic acid and glycerol, were analyzed, including molecular structure, physical properties and solubility. Temperature, reactor atmosphere, and time of reaction strongly influenced the solubility, the molecular weight and molecular structure. To improve o-PGS processing and properties it was mixed with PCL to make electrospun scaffolds. In order to process the mixture by electrospinning, homogeneous solutions o-PGS and PCL were prepared. Because PCL is hydrophobic and o-PGS is hydrophilic selected solvent mixtures were tested to form the homogeneous solutions; the materials dissolved in a mixture of THF:DMF:DCM. Typical electrospinning parameters for preparing the tubular scaffolds at room conditions were: voltage 17.5 kV, needle-collector distance 20 cm and, relative humidity 30-35%, flow injection 0.5 to 2.0 ml/h. The initial mechanical properties of the biodegradable scaffolds were better than those made of natural grafts; the Young’s modulus ranged from 7.6 to 13.0 MPa, depending on electrospinning process parameters. The morphology and physical properties of electrospun PGS/PCL tubular scaffolds show useful features not found in similar constructs made by other methods. The 3D tubular scaffolds were built-up of layered porous walls to produce constructs of different pore size and fibers of different diameter. The porous area was one to two orders of magnitude higher than those produced at micrometer scale by conventional melting and dry/wet spinning methods. These scaffolds show useful characteristics for regenerative medicine such as physical properties; nanometric diameters; high surface/volume ratio; and potentiallity for adhesion and growth of living cells.
Were synthesized four new hybrid hardener agents type amino tertiary functionalized with allyl groups from : l, 6-Hexanediamine, Diethylenetriamine, Trietilentriamine and Tris (2-aminoethyl) amine, using the basic nucleophilic substitution mechanism, replacing bromide by amino tertiary group in the presence of tetrabutylammonium bromide as phase transfer agent, producing allyl amine corresponding: ALA-4, ALA-5, ALA-6 and TRIS respectively, which were evaluated as a hardening of epoxy resin DGEBA through photopolymerization process by UV ligth curing, adding a 10, 20 and 40% molar percentage of hybrid materials and the thiol corresponding to carry out the thiol-ene reaction (TMP TMP, PTKMP) with DMPA as initiator. The resinic materials obtained, were evaluated by the technique of dynamic mechanical analysis (DMA) at a heating rate of 5° C/min in a range from - 50° C to 150° C in nitrogen atmosphere. The formulations with hybrid hardening agent ALA 4- 20% -PTKMP and TRIS 10% -PTKMP were the materials with modulus 2289, 2971 Mpa and tgs of 102,103°C, respectively.
Activation of carbon using polypyrrole as activating agent is searched through Molecular Modeling. The Geometry Optimizations carried out helped to observe carbon effect when is attacked by a polymer in order to give an estimation of the pore size diameter of carbon. In this first approximation pore size diameters is about 30 % with respect to BET (Brunauer, P. Emmett y E. Teller) isotherms experimental data.
Polymer-clay nanocomposites are compounds in which nanoclay particles are distributed in a polymer matrix. Epoxy-clay nanocomposites have become a very interesting topic among researchers in the past two decades because nanoclays have a positive effect on the mechanical, thermal and especially barrier anticorrosive performance of the polymers. In this study, epoxy-montmorillonite organoclay (OMMT) nanocomposite coatings were prepared and deposited on carbon steel substrates. The coatings were prepared through in situ polymerization and by UV-curing technique. The OMMT was added to epoxy resin at loadings between 0 wt.% and 5 wt.%, the particles of OMMT were dispersed using forced agitation-sonication and deposited on carbon steel coupons. The nanocomposite coatings obtained have been characterized by scanning electron microscopy (SEM), spectroscopy Fourier transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and evaluated their corrosion protection effect on cold rolled carbon steel coupons by performing visual analysis. The X-ray analysis showed that exfoliation occurred for the OMMT in the polymer matrix, the SEM analysis showed that OMMT was homogenous dispersed in the polymer matrix and the coatings were uniform. The FTIR analysis showed the characteristic bands of epoxy resin and OMMT in the composite. The results showed that 1 wt.% OMMT coating exhibit better anticorrosive properties than pure epoxy.
In this paper, the formation of Langmuir-Blodgett films of poly(p-acryloylaminophenylmethylphosphonic) acid polymers, with general formula (C10H12NPO4)n are reported. The Langmuir-Blodgett (LB) technique was used for building ordered nanostructures in molecular assemblies of these polymers, which were able to form stable films. At the air-water interface, these polymers (with low and high molecular weight) formed Langmuir (L) monolayers, which were characterized by surface pressure versus molecular area (π-A) isotherms and Brewster´s Angle Microscopy (BAM). Using the LB method, molecular mono and multilayer films of these polymers were prepared and transferred onto glass substrates forming Z-type multilayers, with a transfer ratio close to unity. These LB films were characterized by Atomic Force Microscopy (AFM).
New organic materials with semiconductor behavior were prepared from diphenyldiacetylene and aromatic amines with withdrawing groups by Reisch-Schulte reaction and characterized by IR, RMN spectroscopy. The obtained materials share the property of having electron withdrawing groups joint to the attached aromatic ring, it seems this feature accounts in large fashion to improve the semiconducting behavior of this kind of substances, this topic was studied by means theoretical calculations and the results are also discussed. The calculations were carried out by means the Gaussian09 software and all the involved species were geometrically optimized.
In recent decades conducting polymers have attracted attention due to their promising and versatile applications in different fields. There is a considerable interest in the application of nanotubes multilayer carbon (MWCNT) because of their unique structure, high electrical conductivity, high chemical stability, and high surface-to-volume ratio. These properties make MWCNT extremely attractive for fabricating sensors. Composites based on a matrix of a biopolymer such as the chitosan (CS) with a lot of conductive polymers or (MWCNT), have received increasing attention due to their attractive structural, mechanical and electrical properties that could have applications in different fields such as tissue engineering, biomedicine, and manufacture of sensors and biosensors. Have been reported conducting polymer composites with an extensive range of interesting mechanical and electrical properties, which is reported in this paper to obtain films by ultrasonic bath mixing of Chitosan 3% w/v using polypyrrole (PPy) and multilayer carbon nanotubes. Surface characterization was performed using scanning electron microscopy (SEM). The electrical properties were analyzed using electrochemical impedance spectroscopy (EIS) in a frequency range 0.01 - 10E+5 Hz to 10 mV AC. The results show that the films of CS/PPy/MWCNT have a homogeneous distribution where the chitosan envelops the loads, while for EIS retention load was observed within the matrix observing these materials in accordance with the equivalent circuit of Warburg showing diffusional process.
In the last decades the interest in organic conductors has growth, so they have become the object of study of many research groups that are interested in developing new materials with important conducting properties. The charge transfer complexes (CTC) represent an important kind of organic conductors, because they exhibit high conductivity values, as well as versatility for their design.
In this work, the charge transfer complex (CTC) formed by substituted pyrrole and tetrathiofulvalene (TTF) was obtained by means electrochemical synthesis, the resultant colored mix was characterized by Mass spectrometry, NMR and EPR studies, its intrinsic electronic behavior was measured by a four point probe method, besides theoretical calculations were carried out on the possible structures of the resultant molecular adduct. All the results show that there is a net transfer of an electron between both organic moieties in a solution giving place to a semiconductor species.
This work shows the development of several models for chain-growth polymerizations that admit the direct calculation of the complete molecular weight distribution of the polymer. The direct and complete calculation implies that no statistical mean values are employed as in the moments method neither numerical approximations like in the minimum-squared based methods. The free radical polymerization of ethylene (LDPE) and the coordination via metallocenes polymerization of ethylene (HDPE) are taken as examples for analysis.
In the free radical polymerization case, the conventional scheme for chain-growth polymerization is adopted, with steps for initiation, propagation, chain transfer to small species and the additional step of chain transfer to dead chains . The kinetic parameter are obtained from the open literature. Two kind of reactors were modelled: batch and continuous stirred tank reactor. For this last case, a simulation strategy was considered in which the run started from an initial known population of dead chains. Results show that typical non-linear polymerization profiles for the molecular weight distribution are obtained. For the coordination polymerization of ethylene via metalocenes, the standard coordination model was employed . A two-site catalyst was considered and kinetic parameters reported in the open literature were used. For this study an experimental program in a lab-scale reactor was undertaken in order to obtain modelling data . Results show that the standard model adequately reproduces the experimental data in the kinetic and molecular attributes of the polymer.