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1.
J Am Chem Soc ; 145(1): 216-223, 2023 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-36541447

RESUMO

Protein nanocages are of increasing interest for use as drug capsules, but the encapsulation and release of drug molecules at appropriate times require the reversible association and dissociation of the nanocages. One promising approach to addressing this challenge is the design of metal-dependent associating proteins. Such designed proteins typically have Cys or His residues at the protein surface for connecting the associating proteins through metal-ion coordination. However, Cys and His residues favor interactions with soft and borderline metal ions, such as Au+ and Zn2+, classified by the hard and soft acids and bases concept, restricting the types of metal ions available to drive association. Here, we show the alkaline earth (AE) metal-dependent association of the recently designed artificial protein nanocage TIP60, which is composed of 60-mer fusion proteins. The introduction of a Glu (hard base) mutation to the fusion protein (K67E mutant) prevented the formation of the 60-mer but formed the expected cage structure in the presence of Ca, Sr, or Ba ions (hard acids). Cryogenic electron microscopy (cryo-EM) analysis indicated a Ba ion at the interface of the subunits. Furthermore, we demonstrated the encapsulation and release of single-stranded DNA molecules using this system. Our results provide insights into the design of AE metal-dependent association and dissociation mechanisms for proteins.


Assuntos
Metais Alcalinoterrosos , Metais , Metais Alcalinoterrosos/química , Metais/química , Íons , DNA de Cadeia Simples
2.
Adv Sci (Weinh) ; 9(27): e2202811, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35871554

RESUMO

Ammonia recently has gained increasing attention as a carrier for the efficient and safe usage of hydrogen to further advance the hydrogen economy. However, there is a pressing need to develop new ammonia synthesis techniques to overcome the problem of intense energy consumption associated with the widely used Haber-Bosch process. Chemical looping ammonia synthesis (CLAS) is a promising approach to tackle this problem, but the ideal redox materials to drive these chemical looping processes are yet to be discovered. Here, by mining the well-established MP database, the reaction free energies for CLAS involving 1699 bicationic inorganic redox pairs are screened to comprehensively investigate their potentials as efficient redox materials in four different CLAS schemes. A state-of-the-art machine learning strategy is further deployed to significantly widen the chemical space for discovering the promising redox materials from more than half a million candidates. Most importantly, using the three-step H2 O-CL as an example, a new metric is introduced to determine bicationic redox pairs that are "cooperatively enhanced" compared to their corresponding monocationic counterparts. It is found that bicationic compounds containing a combination of alkali/alkaline-earth metals and transition metal (TM)/post-TM/metalloid elements are compounds that are particularly promising in this respect.


Assuntos
Metaloides , Elementos de Transição , Álcalis , Amônia/química , Ensaios de Triagem em Larga Escala , Hidrogênio/química , Metais Alcalinoterrosos , Oxirredução
3.
Bioresour Technol ; 358: 127403, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35654322

RESUMO

Knowing the effect of specific alkali and alkali earth metals forms is vital for the high-efficient gasification of biomass. This work developed a two-step leaching method to pretreat cornstalk, dividing the inorganic metals into water-soluble (K+, 74 wt%), acid-soluble (Al3+, Ca2+, Fe2+, etc) and insoluble (Si4+) substances. The water-soluble K+ was mainly in KCl form, the acid-soluble metals were removed in phosphates and sulfates forms. The rapid gasification properties of raw material, water leaching residue and acid leaching residue indicated that KCl was the key factor to enhance the hydrogen yield and gasification efficiency. Apart from K+, the alkali earth metals (Ca2+, Mg2+) also had a little catalytic effect on producing hydrogen. When the feedstock was out of metal cations, the syngas was mainly composed of CO. The basic ions to acid ions ratio was linearly related to the syngas quality, which could conduct the flux additives.


Assuntos
Gases , Vapor , Álcalis , Biomassa , Hidrogênio , Metais , Metais Alcalinoterrosos , Água
4.
Phys Chem Chem Phys ; 24(20): 12121-12125, 2022 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-35545953

RESUMO

Microhydrated H2-tagged ion pairs (Ca2+, AcO-)(H2O)n=0-8 and (Ba2+, AcO-)(H2O)n=0-5 are investigated by IR photodissociation laser spectroscopy and DFT-D frequency calculations. The detailed picture of the first steps of ion dissociation reveals two mechanisms, where water molecules promote dissociation either directly or indirectly depending on the nature of the cation.


Assuntos
Metais Alcalinoterrosos , Água , Ácidos Carboxílicos , Cátions , Metais Alcalinoterrosos/química , Água/química
5.
Molecules ; 27(6)2022 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-35335196

RESUMO

The preparation and characterization of products of the photochemical and thermochemical rearrangements of 19-membered azoxybenzocrowns with two, bulky, tert-butyl substituents in benzene rings in the para positions to oligooxyethylene fragments (meta positions to azoxy group, i.e., t-Bu-19-Azo-O have been presented. In photochemical rearrangement, two colored typical products were expected, i.e., 19-membered o-hydroxy-m,m'-di-tert-butyl-azobenzocrown (t-Bu-19-o-OH) and 19-membered p-hydroxy-m,m'-di-tert-butyl-azobenzocrown (t-Bu-19-p-OH). In experiments, two colored atypical macrocyclic derivatives, one 6-membered and one 5-membered ring, bearing an aldehyde group (t-Bu-19-al) or intramolecular ester group (t-Bu-20-ester), were obtained. Photochemical rearrangement led to one more macrocyclic product being isolated and identified: a 17-membered colorless compound, without an azo moiety, t-Bu-17-p-OH. The yield of the individual compounds was significantly influenced by the reaction conditions. Thermochemical rearrangement led to t-Bu-20-ester as the main product. The structures of the four crystalline products of the rearrangement-t-Bu-19-o-OH, t-Bu-19-p-OH, t-Bu-20-ester and t-Bu-17-p-OH-were determined by the X-ray method. Structures in solution of atypical derivatives (t-Bu-19-al and t-Bu-20-ester) and t-Bu-19-p-OH were defined using NMR spectroscopy. For the newly obtained hydroxyazobenzocrowns, the azo-phenol⇄quinone-hydrazone tautomeric equilibrium was investigated using spectroscopic methods. Complexation studies of alkali and alkaline earth metal cations were studied using UV-Vis absorption spectroscopy. 1H NMR spectroscopy was additionally used to study the cation recognition of metal cations. Cation binding studies in acetonitrile have shown high selectivity towards calcium over magnesium for t-Bu-19-o-OH.


Assuntos
Ésteres , Metais Alcalinoterrosos , Cristalografia por Raios X , Espectroscopia de Ressonância Magnética , Quinonas
6.
Waste Manag ; 137: 190-199, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34794037

RESUMO

A significant amount of chlorine, and alkali and alkaline earth metal (AAEM) in food waste has been a major limitation to the utilization of food waste as fuel. The present study aims to investigate the behavior of chlorine and AAEM in food waste biochar during pyrolysis, demineralization, and combustion. Food waste compost (FWC) and food waste feedstock (FWF) were selected as raw materials. Three different pyrolysis temperatures from 300 to 500 °C and two demineralization processes, water and CO2-saturated water, were employed. As the pyrolysis temperature increased, crystallized salt was removed through demineralization, which further increased the heating value. Effective removal of chlorine was demonstrated in both demineralization methods. During demineralization, re-adsorption of Ca on food waste biochar occurred, which was alleviated by CO2-water demineralization. The total amounts of volatilized Cl and AAEM after CO2-water demineralization were reduced by 74.79-99.38% for FWF and 98.34-99.9% for FWC compared to raw biochar. Furthermore, slagging and fouling potentials for all food waste biochar samples were estimated using various indices. The proposed behavior of Cl and AAEM in food waste biochar during various fabrication conditions provides insight into how food waste biochar can be applied in thermos-electric power plant for co-firing with coal.


Assuntos
Cloro , Eliminação de Resíduos , Álcalis , Carvão Vegetal , Alimentos , Metais Alcalinoterrosos
7.
Chemosphere ; 291(Pt 1): 132785, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-34742758

RESUMO

Hydrothermal carbonization (HTC) can improve biomass quality in both physical and chemical aspects for energy application. This study aims to investigate the characteristics and reactivities of rape straw (RS) hydrochars. Hydrochars were prepared at 160-240 °C with residence time of 15-120 min. Mass yield, energy yield, microstructure, functional group and migration of alkali and alkaline earth metals (AAEMs) were studied to evaluate the influence of different conditions on properties of hydrochar. The results showed that O/C and H/C ratio decreased, while the higher heating value (HHV) increased with increasing temperature and residence time. The effect of increasing temperature on hydrochar properties was more significant than residence time. The structure was changed, and hydrochar possessed a more stable form after the aromatization reaction. For the gasification reactivity of hydrochar, decomposition rate curves showed that the peak of pyrolysis and gasification moved to a higher temperature region with the increasing of HTC temperature because of the developed aromatic structures in hydrochar. The pyrolysis activation energy decreased from raw RS 71.68 to 41.03 kJ/mol in 240 °C, while gasification activation energy increased from 80.42 to 251.30 kJ/mol. Moreover, it was found that HTC can reduce the content of AAEMs efficiently and the best removal condition is 200 °C. Ca content dropped to a minimum value at 200 °C and then increased at higher temperature which may be caused by well-developed pore structure in hydrochars. This study provides basic data for comprehensive utilization of rape straw and migration mechanism of AAEMs in HTC process.


Assuntos
Carbono , Calefação , Biomassa , Metais Alcalinoterrosos , Temperatura
8.
Dalton Trans ; 50(47): 17438-17454, 2021 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-34766180

RESUMO

With the steady development of metal-organic framework (MOF) materials, this peculiar class of three-dimensional materials has found application prospects in a myriad of areas. The integration of different metals with various categories of ligands engendered a full gamut of frameworks, which of course are supplemented by diversified modification methods. Amongst many metal centers utilized to design and synthesize targeted MOFs, alkali/alkaline earth metal-based MOFs are gaining significant attention because these metal centers can be regarded as human endogenous metals. Numerous studies have shown that alkali/alkaline earth metal MOFs (A/A-E MOFs) tend to have better properties than other metals. This is because A/A-E MOFs offer better biocompatibility, so it is expected to be used in a broader field of biomedicine in the near future. This review mainly introduces the application of A/A-E MOF materials in drug delivery, sensing, and some materials with unique biomedical applications, and elaborates the challenges, obstacles and development of some A/A-E MOF materials in the biomedical field.


Assuntos
Materiais Biocompatíveis/química , Pesquisa Biomédica , Estruturas Metalorgânicas/química , Metais Alcalinos/química , Metais Alcalinoterrosos/química , Sistemas de Liberação de Medicamentos , Humanos
9.
J Phys Chem B ; 125(44): 12135-12146, 2021 11 11.
Artigo em Inglês | MEDLINE | ID: mdl-34706195

RESUMO

To investigate the ability of alkaline earth metal ions to tune ion-mediated DNA adsorption, hydrated Mg2+, Ca2+, Sr2+, and Ba2+ ions bound to a carboxylate anion, phosphate anion, and guanine nucleobase were modeled using density functional theory (DFT) and a combined explicit and continuum solvent model. The large first solvation shell of Ba2+ requires a larger solute cavity defined by a solvent-accessible surface, which is used to model all hydrated ions. Alkaline earth metal ions bind indirectly or directly to each binding site. DFT binding energies decrease with increasing ion size, which is likely due to ion size and hydration structure, rather than quantum effects such as charge transfer. However, charge transfer explains weaker ion binding to guanine compared to phosphate or carboxylate. Overall, carboxylate and phosphate anions are expected to compete equally for hydrated Mg2+, Ca2+, Sr2+, and Ba2+ ions and larger alkaline earth metal ions may induce weaker ion-mediated adsorption. The ion size and hydration structure of alkaline earth metal ions may effectively tune ion-mediated adsorption processes, such as DNA adsorption to functionalized surfaces.


Assuntos
Guanina , Fosfatos , Ânions , Íons , Metais Alcalinoterrosos
10.
Chem Rec ; 21(8): 1898-1911, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34197009

RESUMO

Biodegradable polyesters such as poly(ϵ-caprolactone) (PCL) and poly(lactic acid) (PLA) have been considered for use in several areas, such as drug delivery devices, sutures, tissue engineering, and GBR membranes, due to its bio-renewability, biodegradability, and biocompatibility. Several synthetic techniques for the preparation of polyesters have been reported in the literature, amongst which the ring-opening polymerization (ROP) of cyclic esters is the most efficient. A convenient approach to access iso-selective PLAs is polymerization of racemic lactide (rac-LA), which shows excellent stereoregularity without the need for costly chiral auxiliaries or ligands. In this personal account, we review a series of methods that have been practiced to the synthesis of biodegradable polyesters from various cyclic monomers using alkali and alkaline earth metal complexes as efficient catalysts.


Assuntos
Complexos de Coordenação/química , Metais Alcalinos/química , Metais Alcalinoterrosos/química , Poliésteres/química , Boranos/química , Catálise , Calcogênios/química , Ciclização , Ésteres/química , Poliésteres/síntese química
11.
J Phys Chem Lett ; 12(23): 5587-5592, 2021 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-34109791

RESUMO

The confinement effect of biological ion channels regulates the transport of molecules and ions due to angstrom-sized pores. The structure of the potassium channel has a selection region (3-4 Å), a cavity (10 Å), and a gated region, while ZIF-8 has intrinsic pores with a 3.4 Å aperture and an 11.6 Å cavity similar to those of the potassium channel. Inspired by this, we constructed the glass/ZIF-8 hybrid membrane through an electrochemical growth process to explore the kinetics of the ion transmembrane by I-V curves and electrochemical impedance spectroscopy. These complementary approaches yield highly correlated results that show that ion transportation of the ZIF-8 membrane follows Arrhenius behavior. The rates of ions are controlled by the transmembrane activation energy, in which the ionic charge and radius play an important role.


Assuntos
Imidazóis/farmacocinética , Estruturas Metalorgânicas/farmacocinética , Metais Alcalinoterrosos/farmacocinética , Nanotecnologia/métodos , Canais de Potássio/farmacocinética , Imidazóis/química , Canais Iônicos/química , Canais Iônicos/farmacocinética , Transporte de Íons/fisiologia , Cinética , Estruturas Metalorgânicas/química , Metais Alcalinoterrosos/química , Canais de Potássio/química
12.
J Environ Sci (China) ; 104: 102-112, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33985713

RESUMO

Herein, Na+ and Ca2+ are introduced to MnO2 through cation-exchange method. The presence of Na+ and Ca2+ significantly enhance the catalytic activity of MnO2 in toluene oxidation. Among them, the Ca-MnO2 catalyst exhibits the best catalytic activity (T50 = 194°C, T90 = 215°C, Ea = 57.2 kJ/mol, reaction rate 8.40 × 10-10 mol/(sec⋅m2) at 210°C. T50 and T90: the temperature of 50% and 90% toluene conversion; Ea: apparent activation energy) and possess high tolerance against 2.0 vol.% water vapor. Results reveal that the increased acidic sites of the MnO2 sample can enhance the adsorption of gaseous toluene, and the mobility of oxygen species and the content of reactive oxygen species in the catalyst are significantly improved due to the formed oxygen vacancy. Thus these two factors result in excellent catalytic performance for toluene oxidation combining with the weak CO2 adsorption ability.


Assuntos
Compostos de Manganês , Tolueno , Catálise , Metais Alcalinoterrosos , Oxirredução , Óxidos
13.
J Org Chem ; 86(10): 7119-7130, 2021 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-33960192

RESUMO

A heterobimetallic zinc/strontium catalyst has been developed for the asymmetric Michael addition of 3-acetoxy-2-oxindoles to ß-ester enones in high yields with excellent enantioselectivities and high diastereoselectivities. This process represents that 3-acetoxy-2-oxindoles can be used as a stable air- and base-tolerant precursor for chiral 3-substituted 3-hydroxy-2-oxindoles.


Assuntos
Aminofenóis , Zinco , Catálise , Ésteres , Indóis , Metais Alcalinoterrosos , Oxindóis , Estereoisomerismo , Sulfonamidas
14.
Chemistry ; 27(37): 9605-9619, 2021 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-33871899

RESUMO

Photoresponsive materials are a key part of the age of smart technology that have potential in a broad range of applications. Coordination networks (CNs) are widely used due to their designability and stability. In this work, three novel alkaline earth metal coordination networks (AEM-CNs): [Mg(CMNDI)(H2 O)2 ], [Ca(CMNDI)(H2 O)2 ]⋅H2 O, and [Sr(CMNDI)(H2 O)(DMF)] with fsl, cds, and scn topology nets were synthetized via N,N'-bis(carboxymethyl)-1,4,5,8-naphthalenediimide (H2 CMNDI); the scn net is not found in the Reticular Chemistry Structure Resource or ToposPro. The reusable and sensitive photochromic properties of the three CNs enable them to be used as secret inks or ultraviolet detectors. In addition, the CNs also exhibited reusable photoluminescent turn-off toward the drug molecules, balsalazide disodium (Bal.) and colchicine (Col.), with good limits of detection of 0.16 and 0.70 µM. To the best of our knowledge, this is the first study of a fluorescence sensor for Bal. Thus, the AEM-CNs provide a design idea for integrated photoresponsive materials that could be further improved in the near future by further study.


Assuntos
Metais Alcalinoterrosos
15.
J Environ Sci (China) ; 103: 172-184, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33743899

RESUMO

To improve the removal capacity of NO + O2 effectively, the alkaline earth metal-doped order mesoporous carbon (A-C-FDU-15(0.001) (A = Mg, Ca, Sr and Ba)) and Mg-C-FDU-15(x) (x = 0.001-0.003) samples were prepared, and their physicochemical and NO + O2 adsorption properties were determined by means of various techniques. The results show that the sequence in (NO + O2) adsorption performance was as follows: Mg-C-FDU-15(0.001) (93.2 mg/g) > Ca-C-FDU-15(0.001) (82.2 mg/g) > Sr-C-FDU-15(0.001) (76.1 mg/g) > Ba-C-FDU-15(0.001) (72.9 mg/g) > C-FDU-15 (67.1 mg/g). Among all of the A-C-FDU-15(0.001) samples, Mg-C-FDU-15(0.001) possessed the highest (NO + O2) adsorption capacity (106.2 mg/g). The species of alkaline earth metals and basic sites were important factors determining the adsorption of NO + O2 on the A-C-FDU-15(x) samples, and (NO + O2) adsorption on the samples was mainly chemical adsorption. Combined with the results of (NO + O2)-temperature-programmed desorption ((NO + O2)-TPD) and in situ diffused reflectance infrared Fourier transform spectroscopy (DRIFTS) characterization, we deduced that there were two main pathways of (NO + O2) adsorption: one was first the conversion of NO and O2 to NO2 and then part of NO2 was converted to NO2- and NO3-; and the other was the direct oxidation of NO to NO2- and NO3-.


Assuntos
Temperatura Baixa , Metais Alcalinoterrosos , Adsorção , Oxirredução , Temperatura
16.
Anal Biochem ; 616: 114099, 2021 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-33388294

RESUMO

Precipitation of DNA is performed frequently in molecular biology laboratories for the purpose of purification and concentration of samples and also for transfer of DNA into cells. Metal ions are used to facilitate these processes, though their precise functions are not well characterized. In the current study we have investigated the precipitation of double-stranded DNA by group 1 and group 2 metal ions. Double-stranded DNAs were not sedimented efficiently by metals alone, even at high concentrations. Increasing the pH to 11 or higher caused strong DNA precipitation in the presence of the divalent group 2 metals magnesium, calcium, strontium and barium, but not group 1 metals. Group 2 sedimentation profiles were distinctly different from that of the transition metal zinc, which caused precipitation at pH 8. Analysis of DNAs recovered from precipitates formed with calcium revealed that structural integrity was retained and that sedimentation efficiency was largely size-independent above 400 bp. Several tests supported a model whereby single-stranded DNA regions formed by denaturation at high pH became bound by the divalent metal cations. Neutralization of negative surface charges reduced the repulsive forces between molecules, leading to formation of insoluble aggregates that could be further stabilized by cation bridging (ionic crosslinking).


Assuntos
Precipitação Química , DNA/química , Metais Alcalinos/química , Metais Alcalinoterrosos/química , Cátions Bivalentes/química , Cátions Monovalentes/química , Cloretos/química , DNA/isolamento & purificação , Concentração de Íons de Hidrogênio , Espectroscopia Fotoeletrônica , Zinco/química
17.
J Environ Sci (China) ; 99: 119-129, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33183689

RESUMO

Activated carbon (AC) has been widely used in the removal of SO2 from flue gas owing to its well-developed pore structure and abundant functional groups. Herein, the effect of alkali/alkaline earth metals on sulfur migration was investigated based on the dynamic adsorption and temperature programmed desorption experiment. The adsorption and desorption properties of six types of AC (three commercial and three laboratory-made) were carried out on a fixed-bed experimental device, and the physical and chemical properties of samples were determined by X-ray fluorescence, X-ray diffraction, scanning electron microscopy/energy dispersive X-ray, and X-ray photoelectron spectroscopy analysis. The experimental results showed that the adsorbed SO2 cannot be completely desorbed by increasing the regeneration temperature (350 - 850°C), while the SO2 fixed in the AC combines with the Ca-based minerals in the ash to form a stable sulfate. For different samples, higher ash content, higher CaO content in the ash and a more developed pore structure lead to a higher SO2 fixation rate. Moreover, the multiple adsorption-desorption cycles experiment showed that the effect of SO2 fixation is mainly reflected in the first cycle, after which the adsorption and desorption amount are approximately the same. This study elucidates the effect of alkali/alkaline earth metals on the adsorption-desorption cycle of AC, which provides a deeper understanding of sulfur migration in the AC flue gas desulfurization process.


Assuntos
Carvão Vegetal , Dióxido de Enxofre , Adsorção , Álcalis , Metais Alcalinoterrosos , Enxofre
18.
J Trace Elem Med Biol ; 63: 126662, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33126039

RESUMO

BACKGROUND: Some elements were claimed to play a role in the pathogenesis of congenital heart defects (CHD) and influence the general well-being and health of these children. OBJECTIVES: We aimed to assess the levels of some elements simultaneously in the blood and teeth samples of children with cyanotic and acyanotic CHD compared with healthy children. METHODS: A total of 39 children with CHD (11 with cyanotic and 28 with acyanotic CHD) and 42 age- and sex-adjusted controls were enrolled. Levels of 13 elements, including magnesium, phosphorus, calcium, chromium, manganese, iron, copper, zinc, strontium, cadmium, lead, mercury, and molybdenum, were assessed using inductively coupled plasma mass spectrometry. RESULTS: Children with cyanotic and acyanotic CHD had significantly lower teeth calcium and calcium/phosphorus ratio as compared to the controls after adjusting for confounders. The mean blood iron level was found to be significantly higher in the cyanotic CHD group compared to the other groups. In addition, children with acyanotic CHD had significantly higher teeth copper levels, higher blood molybdenum and lower blood magnesium levels compared to the healthy control group. Blood cadmium and mercury levels were found to be significantly elevated in both the cyanotic and acyanotic CHD groups compared to the healthy control group. There were no differences in toxic metal levels of teeth in cases with CHD. CONCLUSION: Monitoring adequate and balanced gestational micronutrient intake might support not only maternal health but also fetal cardiac development and infant well-being. Supplementation of magnesium should be evaluated in patients having CHD.


Assuntos
Cardiopatias Congênitas/diagnóstico , Metais Alcalinoterrosos/análise , Fósforo/análise , Dente/química , Oligoelementos/análise , Estudos de Casos e Controles , Criança , Feminino , Cardiopatias Congênitas/sangue , Humanos , Masculino , Espectrometria de Massas , Estado Nutricional
19.
Sci Rep ; 11(1): 19874, 2021 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-34615988

RESUMO

We report here hourly variations of Mg/Ca, Sr/Ca, and Ba/Ca ratios in a Mediterranean mussel shell (Mytilus galloprovincialis) collected at the Otsuchi bay, on the Pacific coast of northeastern Japan. This bivalve was living in the intertidal zone, where such organisms are known to form a daily or bidaily growth line comprised of abundant organic matter. Mg/Ca ratios of the inner surface of the outer shell layer, corresponding to the most recent date, show cyclic changes at 25-90 µm intervals, while no interpretable variations are observed in Sr/Ca and Ba/Ca ratios. High Mg/Ca ratios were probably established by (1) cessation of the external supply of Ca and organic layer forming when the shell is closed at low tide, and (2) the strong binding of Mg to the organic layer, but not of Sr and Ba. Immediately following the great tsunami induced by the 2011 Tohoku earthquake, Mg/Ca enrichment occurred, up to 10 times that of normal low tide, while apparent Ba/Ca enrichment was observed for only a few days following the event, therefore serving a proxy of the past tsunami. Following the tsunami, periodic peaks and troughs in Mg/Ca continued, perhaps due to a biological memory effect as an endogenous clock.


Assuntos
Exoesqueleto/metabolismo , Mytilus/fisiologia , Tsunamis , Exoesqueleto/química , Animais , Biomarcadores , Metais Alcalinoterrosos/análise , Metais Alcalinoterrosos/metabolismo , Análise Espectral , Fatores de Tempo
20.
Artigo em Inglês | MEDLINE | ID: mdl-33332983

RESUMO

Chocolate, one of the most popular sweets in the world, is consumed by people of all ages. Available data point to significant increases in consumption and production. However, successful determination of elements in chocolate is still difficult because of the characteristics of the matrix which contains a high content of organic compounds, like hydrogenated vegetable oil, vegetable fats, solids from malt extract, salts, emulsifiers, etc., causing problems with appropriate decomposition or digestion of sample. In this study, chocolate samples were prepared according to two procedures: water bath and microwave-assisted mineralisation. The use of Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) allowed us to determine the elemental composition of dark, milk, and white chocolate bars available on the Polish market as well as a cacao sample (100% cocoa powder). The elements assessed were Al, Ba, Ca, Cu, Fe, K, Mg, Mn, Na, Ni, P, S, Sr, and Zn. The obtained results were used to compare the effectiveness of sample pre-treatment methods and to assess the correlation between the concentrations of specific elements and type of chocolate by the application of chemometric and statistical tools. The research showed that levels of analysed macro- and microelements are directly connected with the type of chocolate, characterised by the variable contents of cocoa paste and added milk. Data for all samples after mineralisation shown that among macroelements P was the most abundant, followed by Mg, Ca, Na, K, and S. The major essential element with the highest level was Fe, followed by Zn and Cu. In the group of toxic metals the highest content was obtained for Ba, then Al and Sr, but none exceeded permissible values prepared by health benefit organisations.


Assuntos
Chocolate/análise , Contaminação de Alimentos/análise , Metais Alcalinoterrosos/análise , Metais Pesados/análise , Fósforo/análise , Enxofre/análise , Animais , Cacau/química , Bovinos , Análise de Alimentos , Micro-Ondas , Leite/química , Análise Espectral , Água/química
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