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1.
J Am Chem Soc ; 146(22): 15473-15478, 2024 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-38782032

RESUMO

The synthesis and characterization of a series of polyantimony anionic clusters are reported. The products [(NbCp)2Sb10]2-, [MSb13]3- (M = Ru/Fe), and [MSb15]3- (M = Ru/Fe) were isolated as either K(18-crown-6) or K([2.2.2]-crypt) salts. The Sb10 ring contained in the [(NbCp)2Sb10]2- cluster can be viewed as an extension of two envelope-like cyclo-Sb5 units and represents by far the largest monocyclic all-antimony species. The clusters [MSb13]3- and [MSb15]3- (M = Ru/Fe) illustrate the variability of crown-like Sb8 ring motifs and reveal the fusion of different antimony fragments featuring unique Sb-Sb chain-like units. The reported synthetic approaches involve the fabrication of a variety of distinctive polyantimony anionic clusters, enhancing our understanding of the coordination chemistry of heavier group 15 elements.

2.
J Am Chem Soc ; 146(20): 14166-14173, 2024 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-38717077

RESUMO

Inorganic fullerene clusters have attracted widespread attention due to their highly symmetrical geometric structures and intrinsic electronic properties. However, cage-like clusters composed of heavy metal elements with high symmetry are rarely reported, and their synthesis is also highly challenging. In this study, we present the synthesis of a [K2(Bi@Pd12@Bi20)]4- cluster that incorporates a {Bi20} cage with pseudo-Ih symmetry, making it the largest main group metal cluster compound composed of the bismuth element to date. Magnetic characterization and theoretical calculations suggest that the spin state of the overall cluster is a quartet. Quantum chemical calculations reveal that the [Bi20]3- cluster has a similar electronic configuration to C606- and the [Bi@Pd12@Bi20]6- cluster exhibits a unique open-shell aromatic character.

3.
Chem Sci ; 15(13): 4981-4988, 2024 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-38550677

RESUMO

We report here the synthesis and characterization of two endohedral Zintl-ion clusters, [Fe4Sn18]4- and [Fe4Pb18]4-, which contain rhombic Fe4 cores. The Fe-Fe bond lengths are all below 2.5 Å, distinctly shorter than in the corresponding Cu clusters, indicating the presence of Fe-Fe bonding. Subtle differences in the structure of the Fe4 core between the two clusters suggest that the change in tetrel element causes a change in electronic ground state, with a very short Fe-Fe bond length of 2.328 Å present across the diagonal of the rhombus in the lead case.

4.
Chem Sci ; 15(3): 1018-1026, 2024 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-38239679

RESUMO

The endohedral Zintl-ion cluster [Fe3Sn18]4- contains a linear Fe3 core with short Fe-Fe bond lengths of 2.4300(9) Å. The ground state is a septet, with significant σ and π contributions to the Fe-Fe bonds. The Sn18 cage is made up of two partially fused Sn9 fragments, and is structurally intermediate between [Ni2CdSn18]6-, where the fragments are clearly separated and [Pd2Sn18]4-, where they are completely fused. It therefore represents an intermediate stage in cluster growth. Analysis of the electronic structure suggests that the presence of the linear Fe-Fe-Fe unit is an important factor in directing reactions towards fusion of the two Sn9 units rather than the alternative of oligomerization via exo bond formation.

5.
Science ; 382(6672): 840-843, 2023 Nov 17.
Artigo em Inglês | MEDLINE | ID: mdl-37972185

RESUMO

The C60 fullerene molecule has attracted tremendous interest for its distinctive nearly spherical structure. By contrast, all-metal counterparts have been elusive: Fullerene-like clusters composed of noncarbon elements typically suffer from instability, resulting in more compact geometries that require multiple embedded atoms or external ligands for stabilization. In this work, we present the synthesis of an all-metal fullerene cluster, [K@Au12Sb20]5-, using a wet-chemistry method. The cluster's structure was determined by single crystal x-ray diffraction, which revealed a fullerene framework consisting of 20 antimony atoms. Theoretical calculations further indicate that this distinct cluster exhibits aromatic behavior.

6.
Biochem Biophys Res Commun ; 679: 37-46, 2023 10 30.
Artigo em Inglês | MEDLINE | ID: mdl-37666046

RESUMO

The virulence of SARS-CoV-2 decreases with increasing infectivity, the primary approaches for antiviral treatments will be preventing or minimizing the complications resulting from virus infection. ADAM metallopeptidase domain 17 (ADAM17) activation by SARS-CoV-2 infection has a dual effect on the development of the disease: increased release of inflammatory cytokines and dysregulation of Angiotensin converting enzyme II (ACE2) on cell surfaces, inflammatory cytokine infiltration and loss of ACE2 protective function lead to a significant increase in the incidence of related complications. Importantly, pathologically activated ADAM17 showed superior features than S protein in regulating ACE2 expression and participating in the intra cellular replication of SARS-CoV-2. In short, SARS-CoV-2 elicits only a limited immune response when it promotes its own replication and pathogenicity through ADAM17. Therefore, the pathological activation of ADAM17 may also represent a diminished innate antiviral defense and an altered strategy of SARS-CoV-2 infection. In this review, we summarized recent advances in our understanding of the pathophysiology of ADAM17, with a focus on the new findings that SARS-CoV-2 affects ADAM17 expression through Furin protein converting enzyme and Mitogen-activated protein kinase (MAPK) pathway, and raises the hypothesis that SARS-CoV-2 may mediates the pathological activation of ADAM17 by hijacking the actin regulatory pathway, and discussed the underlying biological principles.


Assuntos
COVID-19 , Humanos , SARS-CoV-2/metabolismo , Peptidil Dipeptidase A/metabolismo , Enzima de Conversão de Angiotensina 2 , Antivirais/uso terapêutico , Proteína ADAM17
7.
iScience ; 26(10): 107792, 2023 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-37720090

RESUMO

Thousand and one amino acid kinase 2 (TAOK2) is a member of the mammalian sterile 20 kinase family and is implicated in neurodevelopmental disorders; however, its role in neuropathic pain remains unknown. Here, we found that TAOK2 was enriched and activated after chronic constriction injury (CCI) in the rat spinal dorsal horn. Meanwhile, cyclic guanosine monophosphate-adenosine monophosphate synthase (cGAS)-stimulator of interferon genes (STING) signaling was also activated with hyperalgesia. Silencing TAOK2 reversed hyperalgesia and suppressed the activation of cGAS-STING signaling induced by CCI, while pharmacological activation of TAOK2 induced pain hypersensitivity and upregulation of cGAS-STING signaling in naive rats. Furthermore, pharmacological inhibition or gene silencing of cGAS-STING signaling attenuated CCI-induced hyperalgesia. Taken together, these data demonstrate that the activation of spinal TAOK2 contributes to CCI-induced hyperalgesia via cGAS-STING signaling activation, providing new molecular targets for the treatment of neuropathic pain.

8.
Eur J Clin Invest ; 53(10): e14041, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37318151

RESUMO

BACKGROUND: This study aimed to systematically evaluate the role of circulating levels of choline and betaine in the risk of cardiovascular disease (CVD) and all-cause mortality by comprehensively reviewing observational studies. METHODS: This study was conducted according to PRISMA 2020 statement. Six electronic databases, including PubMed, Embase and China National Knowledge Infrastructure (CNKI), were searched for cohort studies and derivative research design types (nested case-control and case-cohort studies) from the date of inception to March 2022. We pooled relative risk (RR) and 95% confidence interval (CI) of the highest versus lowest category and per SD of circulating choline and betaine concentrations in relation to the risk of CVD and all-cause mortality. RESULTS: In the meta-analysis, 17 studies with a total of 33,009 participants were included. Random-effects model results showed that highest versus lowest quantile of circulating choline concentrations were associated with the risk of CVD (RR = 1.29, 95% CI: 1.04-1.61) and all-cause mortality (RR = 1.62, 95% CI: 1.12-2.36). We also observed the risk of CVD were increased 13% (5%-22%) with per SD increment. Furthermore, highest versus lowest quantile of circulating betaine concentrations were not associated with the risk of CVD (RR = 1.07, 95% CI: 0.92-1.24) and all-cause mortality (RR = 1.39, 95% CI: 0.96-2.01). However, the risk of CVD was increased 14% (5%-23%) with per SD increment. CONCLUSIONS: Higher levels of circulating choline were associated with a higher risk of CVD and all-cause mortality.


Assuntos
Betaína , Doenças Cardiovasculares , Humanos , Colina , Doenças Cardiovasculares/epidemiologia , Fatores de Risco , Estudos Prospectivos , Estudos Observacionais como Assunto
9.
BMC Public Health ; 23(1): 468, 2023 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-36899345

RESUMO

OBJECTIVE: To analyze the effects of different dietary types on in type 2 diabetes mellitus (T2DM) and determine the mediating effects of Body Mass Index (BMI) on dietary type with Fasting Plasma Glucose (FPG), Glycosylated Hemoglobin (HbA1c) on the associations in T2DM. METHODS: Data of community-based cross-sectional study with 9602 participants including 3623 men and 5979 women were collected from the project 'Comprehensive Research in prevention and Control of Diabetes mellitus (CRPCD)' conducted by Jiangsu Center for Disease Control and Prevention in 2018. The dietary data were collected from a food frequency qualitative questionnaire (FFQ) and dietary patterns were derived through Latent Class Analysis (LCA). Then, Logistics regression analyses were used to evaluate the associations of FPG, HbA1c with different dietary patterns. The BMI (BMI = height/weight2) was used as a moderator to estimate the mediating effect. Mediation analysis was performed using hypothetical variables, the mediation variables, to identify and explain the observed mechanism of association between the independent and dependent variables while the moderation effect was tested with multiple regression analysis with interaction terms. RESULTS: After completing Latent Class Analysis (LCA), the dietary patterns were divided into three categories: TypeI, TypeII, TypeIII. After adjusting for confounding factors such as gender, age, education level, marital status, family income, smoking, drinking, disease course, HDL-C, LDL-C, TC, TG, oral hypoglycemic drugs, insulin therapy, Hypertension, Coronary heart disease, Stroke, Type III were all significantly associated with HbA1c compared to those with Type I (P < 0.05), and the research showed the patients with Type III had High glycemic control rate. Taking type I as the reference level, the 95% Bootstrap confidence intervals of the relative mediating effect of TypeIII on FPG were (-0.039, -0.005), except 0, indicating that the relative mediating effect was significant (αIII = 0.346*, ßIIIFPG = -0.060*). The mediating effect analysis was performed to demonstrate that BMI was used as a moderator to estimate the moderation effect. CONCLUSIONS: Our findings demonstrate that consuming Type III dietary patterns associates with good glycemic control in T2DM and the BMI associations would be playing a two-way effect between diet and FPG in Chinese population with T2DM, indicated that Type III could not only directly affect FPG, but also affect FPG through the mediating effect of BMI.


Assuntos
Diabetes Mellitus Tipo 2 , Masculino , Humanos , Feminino , Hemoglobinas Glicadas , Glicemia/análise , Estudos Transversais , Índice de Massa Corporal , Controle Glicêmico , China/epidemiologia
10.
Chem Commun (Camb) ; 59(27): 4024-4027, 2023 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-36920786

RESUMO

In this work, we report a low-valent Ga(I) complex, [Ga@Bi10(NbMes)2]3-, with a linear Nb-Ga-Nb fragment, representing the first compound with Nb-Ga and Nb-Bi bonds. Quantum-chemical calculations reveal that the complex is an electron-precise cluster. The possible fragmentation pathway of the title cluster was studied by using electrospray ionization mass spectrometry and theoretical calculations.

11.
Angew Chem Int Ed Engl ; 62(11): e202217316, 2023 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-36642696

RESUMO

We report here the synthesis and structural characterization of the first binary iron arsenide cluster anion, [Fe3 (As3 )3 (As4 )]3- , present in both [K([2.2.2]crypt)]3 [Fe3 (As3 )3 (As4 )] (1) and [K(18-crown-6)]3 [Fe3 (As3 )3 (As4 )]⋅en (2). The cluster contains an Fe3 triangle with three short Fe-Fe bond lengths (2.494(1) Å, 2.459(1) Šand 2.668(2) Šfor 1, 2.471(1) Å, 2.473(1) Šand 2.660(1) Šfor 2), bridged by a 2-butene-like As4 unit. An analysis of the electronic structure using DFT reveals a triplet ground state with direct Fe-Fe bonds stabilizing the Fe3 core.

12.
Rev Sci Instrum ; 93(11): 114103, 2022 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-36461517

RESUMO

Computed tomography angiography (CTA) has become the main imaging technique for cardiovascular diseases. Before performing the transcatheter aortic valve intervention operation, segmenting images of the aortic sinus and nearby cardiovascular tissue from enhanced images of the human heart is essential for auxiliary diagnosis and guiding doctors to make treatment plans. This paper proposes a nnU-Net (no-new-Net) framework based on deep learning (DL) methods to segment the aorta and the heart tissue near the aortic valve in cardiac CTA images, and verifies its accuracy and effectiveness. A total of 130 sets of cardiac CTA image data (88 training sets, 22 validation sets, and 20 test sets) of different subjects have been used for the study. The advantage of the nnU-Net model is that it can automatically perform preprocessing and data augmentation according to the input image data, can dynamically adjust the network structure and parameter configuration, and has a high model generalization ability. Experimental results show that the DL method based on nnU-Net can accurately and effectively complete the segmentation task of cardiac aorta and cardiac tissue near the root on the cardiac CTA dataset, and achieves an average Dice similarity coefficient of 0.9698 ± 0.0081. The actual inference segmentation effect basically meets the preoperative needs of the clinic. Using the DL method based on the nnU-Net model solves the problems of low accuracy in threshold segmentation, bad segmentation of organs with fuzzy edges, and poor adaptability to different patients' cardiac CTA images. nnU-Net will become an excellent DL technology in cardiac CTA image segmentation tasks.


Assuntos
Doenças Cardiovasculares , Aprendizado Profundo , Humanos , Aorta/diagnóstico por imagem , Coração , Tomografia Computadorizada por Raios X
13.
Front Nutr ; 9: 1002044, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36299987

RESUMO

Background and aims: There are limited studies describing the association between dietary intake of one-carbon metabolism nutrients and hyperglycemia. The present study aimed to investigate the association of habitual dietary intake of one-carbon metabolism nutrients with hyperglycemia in a fluorosis area in China, and explored the interaction between these nutrients and fluorosis related to hyperglycemia. Method: In a cross-sectional study, we recruited 901 villagers, ages ranging from 18-75, in Guizhou Province. Dietary data and other covariate data were obtained through an interviewer-administered questionnaire. We collected venous blood samples from participants who had fasted for one night to obtain fasting blood glucose levels and we categorized dietary intake of betaine, total choline, methionine, folate, vitamins B6 and B12, and choline subclasses into quartiles (Q1-Q4). The lowest quartile (Q1) served as the reference group. An unconditional logistic regression model was used to evaluate the protective effects of a dietary intake of one-carbon nutrients against hyperglycemia. We calculated Odds Ratios (ORs) with 95% confidence intervals (CIs). A presence or absence of fluorosis subgroup analysis was performed to determine the potential effect of fluorosis on hyperglycemia. Result: After adjusting for potential confounding factors, we found that a greater intake of dietary vitamin B6, total choline and methyl-donor index was inversely associated with the occurrence of hyperglycemia (P-trend <0.05). However, there were no significant associations between hyperglycemia and the dietary intake of folate, vitamin B12, methionine, and betaine. As for the choline subgroups, it showed that the dietary intake of free choline, phosphatidylcholine, and glycerol phosphatidylcholine was negatively correlated with the occurrence of hyperglycemia (P < 0.05). In contrast, there was no statistical association between dietary phosphatidylcholine and sphingomyelin and hyperglycemia (all P > 0.05). The results of subgroup analysis showed that dietary intake of folate, vitamin B6, total choline, free choline, glycerol phosphorylcholine, and phosphocholine had a protective effect against the occurrence of hyperglycemia in the non-fluorosis subgroup, although no effects were observed in the fluorosis subgroup. There were significant interactions between these nutrients and fluorosis (P = 0.010-0.048). Conclusion: The study demonstrated that higher dietary intake of vitamin B6, total choline, methyl-donor index, free choline, glycerol phosphorylcholine, and phosphocholine in choline compounds were associated with a lower incidence of hyperglycemia. Moreover, the associations were modified by the presence or absence of fluorosis. Further investigation is needed to test the association in large-scale follow-up studies.

14.
Chemistry ; 28(64): e202202651, 2022 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-36124852

RESUMO

Group 14 endohedral clusters containing a metal center inside usually possess a single cage topological structure, but here an unexpected single-metal-filled double-cage cluster, [Pt@Sn17 ]4- (1 a) is reported. It can be seen as a combination of the more extended Pt-filled [Pt@Sn9 ] cage and hollow [Sn9 ] cage sharing a central Sn atom, which is offset from the central position. This double-cage species represents the largest group 14 intermetalloid cluster encapsulating a single transition metal atom. DFT calculations show that the capsule-like architecture of [Sn17 ]4- , similar to that found in [Pt2 @Sn17 ]4- , is unstable if filled with a single Pt atom and collapses to the title cluster 1 a upon geometry optimization. Deviation of the central Sn atom occurs due to the vibronic coupling as a consequence of pseudo-Jahn-Teller distortion leading to the bent Cs -symmetrical structure, in contrast to the more symmetrical D2d cage previously reported in [Ni2 @Sn17 ]4- .

15.
Chemistry ; 28(62): e202202192, 2022 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-35946563

RESUMO

During the past two decades, single-atom-centered medium-sized germanium clusters [M@Gen ] (M=transition metals, n>12) have been extensively explored, both from theoretical perspectives and experimental gas-phase syntheses. However, the actual structural arrangements of the Ge13 and Ge14 endohedral cages are still ambiguous and have long remained an unresolved problem for experimental implementation. In this work, we successfully synthesize 13-/14-vertex Ge clusters [Nb@Ge13 ]3- (1) and [Nb@Ge14 ]3- (2), which are structurally characterized and exhibit unprecedented topologies, neither classical deltahedra nor 3-connected polyhedral structures. Theoretical analysis indicates that the major stabilization of the Ge backbones arises due to the substantial interaction of Ge 4p-AOs with the endohedral Nb 4d-AOs through three/four-center two-electron bonds with an enhanced electron density accumulated over the shortest Nb-Ge13 contact in 1. Low occupancies of the direct two-center two-electron (2c-2e) Nb-Ge and Ge-Ge σ bonds point to a considerable degree of electron delocalization over the Ge cages revealing their electron deficiency.

16.
Front Public Health ; 10: 849173, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35646794

RESUMO

Background: Oxidative stress plays an important role in the pathogenesis of endemic fluorosis. We analyzed associations between oxidative stress-related gene polymorphisms (PON1 rs662, CAT rs769217, rs2300182, and SOD2 rs11968525) and skeletal fluorosis, and examined potential gene-environment interactions with dietary vitamin C, vitamin E, zinc, and selenium intake. Methods: A cross-sectional study was conducted in the Zhijin County, Guizhou Province of China. Skeletal fluorosis was identified according to the Chinese Diagnostic Criteria of Endemic Skeletal Fluorosis. Dietary information was assessed through face-to-face interviews by trained interviewers using a 75-item food frequency questionnaire. The genotype was detected by high throughput TaqMan-MGB RT-PCR technology. Odds ratios (ORs) and 95% CIs were calculated using an unconditional logistic regression model. Results: Intake of vitamin E, zinc, and selenium was found to be inversely associated with the risk of skeletal fluorosis. The multivariable-adjusted ORs were 0.438 (95% CI: 0.268 to 0.715, P-trend < 0.001) for vitamin E, 0.490 (95% CI: 0.298 to 0.805, P-trend = 0.001) for zinc, and 0.532 (95% CI: 0.324 to 0.873, P-trend = 0.010) for selenium when comparing the highest with the lowest quartile. The relationship for vitamin C was not observed after adjustment for risk factors. Furthermore, participants with PON1 rs662 AA genotype had a significantly decreased risk of skeletal fluorosis compared with those with the GG genotype (OR = 0.438, 95% CI: 0.231 to 0.830). GG + AG genotype carriers were 2.212 times more likely to have skeletal fluorosis than AA carriers (OR = 2.212, 95% CI: 1.197 to 4.090). Compared with AA carriers, AG carriers had a 2.182 times higher risk of skeletal fluorosis (OR = 2.182, 95% CI: 1.143 to 4.163). Although we observed the risk of skeletal fluorosis was higher with a lower intake of antioxidant nutrients, the potential interactions between nutrient intake and genetic polymorphisms were not observed. Conclusion: Participants with a higher intake of vitamin E, zinc, and selenium have a lower likelihood of skeletal fluorosis. In addition, the PON1 rs662 polymorphism is related to skeletal fluorosis.


Assuntos
Arildialquilfosfatase , Doenças Ósseas Metabólicas , Antioxidantes , Arildialquilfosfatase/genética , Doenças Ósseas Metabólicas/genética , China/epidemiologia , Estudos Transversais , Humanos , Nutrientes , Estresse Oxidativo/genética , Polimorfismo Genético , Selênio , Vitamina E , Zinco
17.
Chem Sci ; 13(22): 6744-6748, 2022 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-35756517

RESUMO

The development of rational synthetic routes to inorganic arsenide compounds is an important goal because these materials are finding applications in many areas of materials science. In this paper, we show that the binary crown clusters [M@As8]3- (M = Nb, Ta) can be used as synthetic precursors which, when combined with ZnMes2, generate ternary intermetalloid clusters with 12-vertex cages, {M@[As8(ZnMes)4]}3- (M = Nb, Ta). Structural studies are complemented by mass spectrometry and an analysis of the electronic structure using DFT. The synthesis of these clusters presents new opportunities for the construction of As-based nanomaterials.

18.
Asia Pac J Clin Nutr ; 31(2): 320-330, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35766568

RESUMO

BACKGROUND AND OBJECTIVES: Genetic and dietary factors are important contributors to the development of dental fluorosis (DF). This study investigated the association between DF and dietary carotenoids, and explored whether the association was modified by polymorphisms of the antioxidant enzyme superoxide dismutase 2 (SOD2 rs11968525) in Guizhou, China. METHODS AND STUDY DESIGN: A cross-sectional study with a total of 899 adults aged 18-75 years were enrolled in the study. Face-to-face interviews were conducted to assess dietary habits using a validated 75 item food frequency questionnaire (FFQ). Sociodemographic and lifestyle information, and blood and urine samples were also collected. Genotypes were evaluated using TaqMan single nucleotide polymorphism (SNP) Genotyping Assay. RESULTS: There were significant dose-dependent inverse associations of the prevalence of DF with intake of α-carotene, ß-carotene, lutein/zeaxanthin, lycopene and total carotenoids (p-trend ranged from <0.001-0.004). The odds ratios (ORs) and 95% confidence intervals (CIs) of DF comparing the highest against lowest quartile were 0.56 (0.35, 0.92) for α-carotene, 0.53 (0.35, 0.81) for ß-carotene, 0.44 (0.27, 0.74) for lycopene, 0.35 (0.21, 0.58) for lutein/zeaxanthin in combination and 0.42 (0.25, 0.69) for total carotenoids (all p-trend<0.005). Intake of ß-cryptoxanthin was not found to be related to DF. The inverse association of DF with dietary intake of α-carotene and ß-carotene was more evident in individuals with the AG+AA genotype (p-interaction<0.05). CONCLUSIONS: Higher dietary carotenoids were associated with a lower occurrence of DF, polymorphisms in SOD2 (rs 11968525) modified the associations between dietary intake of carotene and DF. These findings provide evidence for precision prevention of fluorosis.


Assuntos
Fluorose Dentária , Superóxido Dismutase/genética , beta Caroteno , Adulto , Carotenoides , China/epidemiologia , Estudos Transversais , Dieta , Ingestão de Alimentos , Fluorose Dentária/epidemiologia , Fluorose Dentária/genética , Humanos , Luteína , Licopeno , Polimorfismo Genético , Inquéritos e Questionários , Zeaxantinas
19.
Chem Commun (Camb) ; 58(42): 6223-6226, 2022 May 24.
Artigo em Inglês | MEDLINE | ID: mdl-35510576

RESUMO

In this work, we synthesize naked tin cluster anion Sn368-, representing the first example of pure Sn nanowire assembled through oxidative coupling reactions of a super atomic cluster Sn94-. Theoretical analysis confirm the presence of aromaticity for each Sn9 unit showing four adjacent aromatic subunits bridged by parallel Sn-Sn bonds.

20.
Nat Commun ; 13(1): 2149, 2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35444180

RESUMO

Understanding the structural changes taking place during the assembly of single atoms leading to the formation of atomic clusters and bulk materials remains challenging. The isolation and theoretical characterization of medium-sized clusters can shed light on the processes that occur during the transition to a solid-state structure. In this work, we synthesize and isolate a continuous 24-atom cluster Ge244-, which is characterized by X-ray diffraction analysis and Energy-dispersive X-ray spectroscopy, showing an elongated structural characteristic. Theoretical analysis reveals that electron delocalization plays a vital role in the formation and stabilization of the prolate cluster. In contrast with carbon atoms, 4 s orbitals of Ge-atoms do not easily hybridize with 4p orbitals and s-type lone-pairs can be localized with high occupancy. Thus, there are not enough electrons to form a stable symmetrical fullerene-like structure such as C24 fullerene. Three aromatic units with two [Ge9] and one [Ge6] species, connected by classical 2c-2e Ge-Ge σ-bonds, are aligned together forming three independent shielding cones and eventually causing a collapse of the global symmetry of the Ge244- cluster.

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