RESUMEN
Particulate matter (PM10) changes have been confirmed as one of the contributory factors affecting human health, the association between PM10 pollution and the hospitalization of chronic obstructive pulmonary disease (COPD) with comorbidity diseases was rarely reported. The same inpatient more than twice times admissions with COPD illness from January 1, 2016 to December 31, 2021 were identified from hospitals in the 17 cities of Henan, Central China. City-specific associations were firstly estimated using the case time series (CTS) model and then combined to obtain the regional average association. The multivariate meta-analytic model produces pooled estimates of the set of coefficients representing the PM10-COPD hospitalizations association across the 17 cities. Cause-specific hospitalization analyses were performed by COPD patients with different comorbidity combinations. A total of 34,348 elderly (age ≥ 65) subjects were analyzed and with a total of 35,122.35 person-years. These coefficients can be used to compute the linear exposure-response curve expressed as relative risk (RR) in per 10 µg/m3 increase in PM10 at lag03, which was 1.0091 (95% CI 1.0070-1.0112) for COPD with comorbidity, 1.0089 (95% CI 1.0067-1.0110) for COPD with circulatory system diseases, 1.0079 (95% CI 1.0052-1.0105) for COPD with respiratory system diseases, 1.0076 (95% CI 1.0032-1.0121) for COPD with endocrine system diseases, and 1.0087 (95% CI 1.0013-1.0162) for COPD with genitourinary system diseases, respectively. Some heterogeneity was found across cities, with estimates ranging from 1.0227 in the Puyang and Jiaozuo to 1.0053 in Henan Provance, China. The effect of higher PM10, on average, was higher in studies for northern cities, with a steeper raise in risk: per 10 µg/m3 increase in PM10, the RR from 1.0062 (95% CI 1.0030-1.0093) for the 10th percentile of latitude to 1.0124 (95% CI 1.0089-1.0160) for the 90th percentile. Our findings indicated that PM10 exposure may increase the risk of hospitalizations for COPD with comorbidity. Moreover, there might be a higher morbidity risk associated with PM10 in northern latitudes, indicating that stricter air quality standards could potentially reduce PM10-related morbidity among individuals with COPD. These findings have implications for the implementation of effective clean air interventions aligned with national climate policies.
Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Enfermedad Pulmonar Obstructiva Crónica , Humanos , Anciano , Contaminantes Atmosféricos/análisis , Ciudades/epidemiología , Contaminación del Aire/análisis , Material Particulado/análisis , Hospitalización , Enfermedad Pulmonar Obstructiva Crónica/epidemiología , China/epidemiología , Comorbilidad , Exposición a Riesgos Ambientales/análisisRESUMEN
BACKGROUND: This study aimed to examine the bidirectional relationship between social isolation and cognitive performance among Chinese middle-aged and older adults. METHODS: We used four waves of data from the China Health and Retirement Longitudinal Study. A latent growth model (LGM) was applied to examine the association between social isolation and cognitive performance across different characteristics. RESULTS: In the analysis, we ultimately included 9,367 participants after excluding respondents with missing key variables. Social isolation and cognitive performance showed significant differences across time. After adjusting for the confounders, there was a significant association between higher social isolation and poor cognitive performance (ß = -1.38, p < 0.001), and higher levels of social isolation resulted in a more pronounced decline in cognition over time (ß = 0.17, p < 0.001). Additionally, the path coefficient between the initial level of cognition at baseline and the slope of social isolation was - 0.07 (p < 0.001) and 0.01 (p = 0.021), respectively. For the correlation between slopes, our study found that females' cognition scores were more susceptible to social isolation (ß = - 2.78, p < 0.001). Similarly, regarding cognition scores, the influence of social isolation was greater among people with education below the primary level (ß = - 2.89, p = 0.002) or a greater number of chronic diseases (ß = - 2.56, p = 0.001). CONCLUSION: Our findings support the bidirectional association between social isolation and cognition. Specifically, higher baseline social isolation and its rate of increase over time contribute to an intensification of cognitive decline at follow-up. Besides, poorer cognitive performance predicted higher social isolation.
Asunto(s)
Cognición , Disfunción Cognitiva , Aislamiento Social , Anciano , Femenino , Humanos , Persona de Mediana Edad , Pueblo Asiatico , Estudios Longitudinales , ChinaRESUMEN
Conversion of N2 into NH3 through the electrochemical nitrogen reduction reaction (NRR) under ambient conditions represents a novel green ammonia synthesis method. The main obstacle for NRR is lack of efficient, stable, and cost-effective catalysts. In this work, by using density functional theory calculations, 16 transition metal-modified Co4 clusters supported on graphdiyne (GDY) as potential NRR catalysts were systematically screened. Through the examinations of stability, N2 activation, selectivity, and activity, Ti-, V-, Cr-, Mn-, and Zr-Co3@GDY were identified as the promising candidates toward NRR. Further explorations on the NRR mechanisms and the Pourbaix diagrams suggest that Ti-Co3@GDY was the most promising candidate catalyst, as it has the lowest limiting potential and high stability under the working conditions. The high activities originate from the synergy effect, where the Co3 cluster acts as the electron donor and the heteroatom serves as the single active site throughout the NRR process. Our results offer a new perspective for advancing sustainable NH3 production.
RESUMEN
The reaction mechanism and kinetics of the simplest Criegee intermediate CH2OO reaction with hydroperoxymethyl formate (HPMF) was investigated at high-level quantum chemistry calculations. HPMF has two reactive functional groups, -C(O)OH and -OOH. The calculated results of thermodynamic data and rate constants indicated that the insertion reactions of CH2OO with -OOH group of HPMF were more favorable than the reactions of CH2OO with -C(O)OH group. The calculated overall rate constant was 2.33 × 10-13 cm3/(moleculeâ sec) at 298 K and the rate constants decreased as the temperature increased from 200 to 480 K. In addition, we also proved the polymerization reaction mechanism between CH2OO and -OOH of HPMF. This theoretical study interpreted the previous experimental results, and supplied the structures of the intermediate products that couldn't be detected during the experiment.
Asunto(s)
Formiatos , Teoría Cuántica , Cinética , Temperatura , TermodinámicaRESUMEN
Using density functional theory combined with the nonequilibrium Green's function method, spin-dependent transport properties of molecular devices consisting of the 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) molecule anchored via C and O linkages to zigzag graphene nanoribbon (ZGNR) electrodes were systematically investigated. Calculation results showed that the two connection modes display a good spin transport performance in both parallel (P) and anti-parallel (AP) configurations. Particularly, oxygen connection significantly improves the spin filtration effect. These observations were validated by analyzing spin-resolved transmission spectra, band structures and spatial distribution of molecular orbitals within the bias window. Further comparison of the results of different models indicated that the linkage plays a crucial role in improving the spin transport properties for the proposed NTCDA-ZGNR system, giving them potential applications in high-performance multifunctional spintronic devices.
RESUMEN
As a promising anode material, TiO2(B) has attracted much attention in recent years due to its high power and capacity performances. First-principles calculations are performed here to reveal the electronic properties and the transport of lithium (Li) in the bulk TiO2(B) with and without atomic doping. It is found that a 4-fold coordinated O atom has the lowest formation energy and the smallest bandgap and is the atom that most easily forms an O-vacancy (Ov). In this work, a series of p-type (N, P, As), n-type (F, Cl, Br), and isoelectronic (S, Se, Te) dopants in TiO2(B) are studied. For n-type dopants, the substitution of the F atom has no significant effect on the electronic structure, which results in the lowest formation energy. This result demonstrates that the F atom can provide high intrinsic stability. Analysis of the insertion process of Li in doped TiO2(B) shows that N-doping is the most competitive choice because it not only introduces a lower bandgap of TiO2(B) but it also has the highest binding energy with Li. The advantage of N-doping is derived from the self-compensation effect. Also, three possible transport paths of Li in TiO2(B) were studied via the CI-NEB method. The results show that the energy barrier of all diffusion paths of F doping is lower than that of pure TiO2(B), where path 2 along the b-axis channel has the lowest energy (0.32 eV). This study is expected to shed some light on the electronic structures of TiO2(B) and the transport properties of Li in it.
RESUMEN
BACKGROUND/AIMS: Some adipokines, such as adiponectin and leptin, have been reported to be involved in the pathogenesis of nonalcoholic fatty liver disease (NAFLD), while the association of adipsin and visfatin with NAFLD still remains unclear. This study aimed to examine the association of circulating adipsin, visfatin, and adiponectin with NAFLD in Chinese adults. METHODS: We recruited a total of 211 eligible subjects, including 100 NAFLD cases and 111 age and sex frequency-matched controls. Circulating adipsin, visfatin, and adiponection concentrations were measured by enzymatic immunoassay. Unconditional logistic regression was conducted to assess the associations between quartiles of adipokines and NAFLD. RESULTS: Compared with the controls, NAFLD cases had higher levels of adipsin and lower levels of visfatin and adiponectin. By multivariate logistic analysis, adjusting for potential confounders, circulating adipsin levels were found to be positively associated with NAFLD risk, and circulating levels of visfatin and adiponectin were inversely associated with the risk of NAFLD (all p-trend < 0.05). The ORs were 3.76 (95% CI 1.27-11.08) for adipsin, 0.30 (95% CI 0.10-0.91) for visfatin, and 0.30 (95% CI 0.10-0.88) for adiponectin comparing subjects in the highest quartile with those in the lowest. After stratified by obesity status, the association of higher adipsin with increased risk of NAFLD was only observed in nonobese group. Additionally, the inverse association between adiponectin and NAFLD was found in both groups. CONCLUSIONS: These results indicated that increased circulating levels of adipsin and decreased circulating levels of visfatin and adiponectin were independently associated with the increased risk of NAFLD.
Asunto(s)
Adiponectina/sangre , Citocinas/sangre , Nicotinamida Fosforribosiltransferasa/sangre , Enfermedad del Hígado Graso no Alcohólico/sangre , Adipoquinas/sangre , Adulto , Pueblo Asiatico , Estudios de Casos y Controles , China , Factor D del Complemento/análisis , Femenino , Humanos , MasculinoRESUMEN
Van der Waals (vdW) heterostructures, which have the advantage of integrating excellent properties of the stacked 2D materials by vdW interactions, have gained increasing attention recently. In this work, within the framework of density functional theory calculations, the electronic properties of vdW heterostructure composed of phosphorene (BP) in black phosphorus phase and GeS monolayer are systematically explored. The results show that the carriers are not separated for both lattice-match and lattice-mismatch heterostructures. For the lattice-match heterostructure, it is found that changing monolayer of GeS to bilayer can increase the energy difference of valence band offsets between GeS and BP, thus realizing electron-hole separation. For the lattice-mismatch heterostructure, altering the layer distance can transform the heterostructure into a typical type-I alignment, but applying the electric field or doping with 2, 3, 5, 6-tetrafluoro-7, 7, 8, 8-tetracyanoquinodimethane (F4TCNQ) can make it display a perfect desirable type-II alignment, where holes migration and electrons transfer are revealed to account respectively for the phenomenon of carrier separation. It is believed that the work would greatly enlarge the potential application of the BP-based heterostructures in photoelectronics and further stimulate the investigation enthusiasms on other fashionable heterostructures and even unassuming heterostructures in which the charming electronic properties can be modulated to emerge by various general methods.
RESUMEN
Tb3+-doped zinc-based coordination polymer nanospindle bundles (Zn-PDC/Tb3+, or [Zn(2,5-PDC)(H2O)2]·H2O/Tb3+) were synthesized by a simple solution precipitation route at room temperature, employing Zn(NO3)2, Tb(NO3)3, and 2,5-Na2PDC as the initial reactants, and a mixture of water and ethanol with the volume ratio of 10:10 as the solvent. The as-obtained nanostructures presented strong fluorescent emission under the excitation of 298 nm light, which was attributed to the characteristic emission of the Tb3+ ion. It was found that the above-mentioned strong fluorescence of the nanostructures could be selectively quenched by cefixime (CFX) in aqueous solution. The other common antibiotics hardly interfered. Thus, as-obtained Zn-PDC/Tb3+ nanostructures could be prepared as a highly sensitive fluorescence probe for selective detection of CFX in an aqueous system. The corresponding detection limit reached 72 ppb. The theoretic calculation and UV-vis absorption experiments confirmed that the fluorescence quenching of Zn-PDC/Tb3+ nanostructures toward CFX should be attributed to the electron transfer and the fluorescence inner filter effect between the fluorescent matter and the analyte. In addition, the strong fluorescence of the nanostructures could also be selectively quenched by acetone in the water system.
RESUMEN
Semiconducting polymer dots (Pdots) with one-, two-photon excitation and dual-emission have been synthesized by coprecipitation of two conjugated polymers including poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) and poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-(1-cyanovinylene-1,4-phenylene)] (CN-PPV) and have been further functionalized with l-tyrosine methyl ester (Tyr-OMe) via electrostatic assembly for ratiometric fluorescent sensing and bioimaging of tyrosinase activity. Tyrosinase-catalyzed oxidation of Tyr-OMe effectively modulate the dual-emission fluorescence of PFO/CN-PPV@Tyr-OMe Pdots from orange to blue through a selective photoinduced electron transfer (PET) process. A two-photon ratiometric sensor at almost zero-background interference and bioimaging of tyrosinase activity have been demonstrated, suggesting the potential biomedical applications of the prepared functionalized Pdots.
Asunto(s)
Microscopía Confocal , Monofenol Monooxigenasa/metabolismo , Polímeros/química , Puntos Cuánticos/química , Semiconductores , Animales , Línea Celular Tumoral , Transporte de Electrón , Colorantes Fluorescentes/química , Colorantes Fluorescentes/metabolismo , Humanos , Ratones , Monofenol Monooxigenasa/sangre , Fotones , Teoría Cuántica , Espectrometría de FluorescenciaRESUMEN
Doping is a vitally important technique that can be used to modulate the properties of two-dimensional materials. In this work, by using first-principles density functional calculations, we investigated the electrical properties of SnSe2 monolayers by p-type/n-type and isoelectronic doping. Substitution at Sn/Se sites was found to be easy if the monolayer was grown under Sn-/Se-poor conditions. Substitutions at Sn sites with metallic atoms (e.g. Ga, Ge, In, Bi, Sb, Pb) resulted in positive substitution energies, which indicated that they were not effective doping candidates. For substitutions at Se sites with nonmetallic atoms, no promising candidates were found for p-type doping (e.g., N, P, As). Among these, N and As showed positive substitution energies. Although P had a negative substitution energy under Sn-rich conditions, it introduced trap states within the band gap. For n-type doping (e.g., F, Cl, Br), all the calculated substitution energies were negative under both Sn- and Se-rich conditions. Br was proven to be a promising candidate, because the impurity introduced a shallow donor level. Finally, for isoelectronic doping (e.g., O, S, Te), the intrinsic semiconducting features of the SnSe2 monolayer did not change, and the contribution from the impurity to the states near the band edge increased with the atomic number.
RESUMEN
Special functionalization of semiconducting polymer dots (Pdots) is highly desired to expand their applications in chemo/biosening. Herein, carboxyl-functionalized poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(1,4-benzo-{2,1',3}-thiadiazole)] dots covalently tagged with aminated ß-cyclodextrin (NH2-CD) have been designed to construct a ratiometric sensor for cholesterol (Cho). Using CD-Pdots as energy donors with rhodamine B (RB) as energy acceptors, a fluorescence resonance energy transfer (FRET) pair has been built because the host-guest interaction between RB and CD attached to Pdots brings donors and acceptors into close proximity. In the presence of Cho, the acceptors will depart from the donors because of the competitive inclusion interaction between Cho and RB with CD, resulting in the hindering of the FRET process between CD-Pdots and RB. On the basis of the turn-on fluorescence of CD-Pdots and turn-off fluorescence of RB, a sensitive ratiometric method for the determination of Cho in the concentration range from 25 to 350 nM with a detection limit of 4.9 nM was achieved. The proposed method was validated to determine free Cho in human serum samples with satisfactory results.
Asunto(s)
Colesterol/análisis , Transferencia Resonante de Energía de Fluorescencia , Polímeros/química , beta-Ciclodextrinas/química , Unión Competitiva , Colesterol/sangre , Colorimetría , Colorantes Fluorescentes/química , Humanos , Límite de Detección , Nanopartículas , Radiometría , Rodaminas/química , Semiconductores , Espectrometría de FluorescenciaRESUMEN
BACKGROUND: It is important to perform the first 12 weeks of rehabilitation without risk of tearing a cuff tendon from its repair site. Our hypothesis was that performing early postoperative rehabilitation with a limitable pendulum exercise device can produce lower retear rate outcomes when it is combined with safe, informed physiotherapy compared with a standardized protocol of rehabilitation performed at home. METHODS: By using an asymmetric arm support brace and an advanced accelerometer, we attempted to determine the benefits of small pendulum exercises (proposed by Long et al). This study enrolled 24 patients to use a monitoring device in standardized small pendulum exercises. Clinical outcomes and magnetic resonance images were evaluated preoperatively and 12 weeks after surgery. RESULTS: While a patient performed pendulum exercises, a therapist used computer imagery to observe whether vertical acceleration was over a given threshold (identified as physiologic tremors), as a warning of and precaution associated with the increased risk of repair failure. Similar self-reported functional outcomes were reported in 2 areas. The rate of recurrent tears was significantly higher for both the medium-sized and large areas in the uninformed home rehabilitation group compared with the informed group. CONCLUSION: The results of monitoring of pendulum exercises to develop informed physical therapeutic methodology were consistent with those of previously published literature. In this study, use of a monitoring device during early rehabilitation was associated with lower retear rates after rotator cuff repair.
Asunto(s)
Terapia por Ejercicio/métodos , Manguito de los Rotadores/cirugía , Traumatismos de los Tendones/rehabilitación , Anciano , Terapia por Ejercicio/instrumentación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Rango del Movimiento Articular , Recurrencia , Lesiones del Manguito de los Rotadores , Traumatismos de los Tendones/cirugía , Resultado del TratamientoRESUMEN
Density functional calculations were preformed to investigate whether adding Ni into a Cu surface (denoted as Cu/Ni) or adding Cu into a Ni surface (Ni/Cu) is more efficient for catalyzing the water-gas shift (WGS)? The reactions of water dissociation and monoxide dissociation were selected to assess the activity and selectivity towards WGS, respectively. Our results show that Ni-atom modification of surfaces is thermodynamically favorable for both reactions. Kinetically, compared with pure Cu, water dissociation is greatly facilitated on Ni-modified surfaces, and the activity is insensitive to the Ni concentration; however, monoxide dissociation is not well-promoted on one Ni-atom-modified surfaces, but two Ni-atom modification can notably decrease the dissociation barriers. Overall, on the basis of these results, we conclude that 1) the catalytic performance of bimetallic metals is superior to monometallic ones; 2) at the same Ni concentration on the surface, Cu/Ni and Ni/Cu alloys have almost the same performance towards WGS; and 3) to acquire high WGS performance, the surface Ni atoms should either be low in concentration or highly dispersed.
RESUMEN
Novel aza-BODIPYs with significant bathochromic shifts were designed and synthesized by installation of strong electron-withdrawing groups on the para-positions of 1,7-phenyls and electron-donating groups on the para-positions of 3,4-phenyls. These dyes show strong NIR fluorescence emissions up to 756 nm, and absorptions up to 720 nm.
Asunto(s)
Compuestos Aza/química , Boratos/química , Compuestos de Boro/química , Colorantes Fluorescentes/química , Porfobilinógeno/análogos & derivados , Porfobilinógeno/química , Electrones , Estructura Molecular , Espectroscopía Infrarroja CortaRESUMEN
OBJECTIVE: The objective of this study was to examine the relationship between sleep duration and prediabetes, as well as to evaluate the influence of inflammation in mediating this association. METHODS: A total of 4632 participants from the China Health and Retirement Longitudinal Study (CHARLS) were included in this study, comprising both baseline and 4-year follow-up data. The prospective relationship between sleep duration and the risk of prediabetes was examined using logistic regression models. We used multinomial logistic regression to evaluate the impact of prediabetes on sleep duration changes over follow-up, assessing the role of C-reactive protein in the association using mediation analysis. RESULTS: Participants with short sleep duration (<5 hours) had a higher risk of prediabetes (odds ratios=1.381 [95% CI: 1.028-1.857]) compared to those with normal sleep durations (7-8 hours). However, excessive sleep durations (≥9 hours) did not show a statistically significant association with prediabetes risk. Moreover, individuals at least 60years old who experienced short sleep durations exhibited a higher risk of prediabetes. Individuals with prediabetes were more likely to have shorter sleep duration than excessive sleep duration (relative risk ratios=1.280 [95% CI: 1.059-1.547]). The mediation analysis revealed a mediating effect of C-reactive protein on the association between prediabetes and reduced sleep duration. CONCLUSIONS: Short sleep duration was identified as a risk factor for the incidence of prediabetes. Conversely, prediabetes was found to contribute to shorter sleep duration rather than excessive sleep duration. Moreover, elevated levels of C-reactive protein may serve as a potential underlying mechanism that links prediabetes with shorter sleep.
Asunto(s)
Inflamación , Estado Prediabético , Sueño , Humanos , Estado Prediabético/epidemiología , Estudios Longitudinales , Masculino , China/epidemiología , Femenino , Persona de Mediana Edad , Factores de Tiempo , Anciano , Factores de Riesgo , Proteína C-Reactiva/análisis , Jubilación/estadística & datos numéricos , Estudios Prospectivos , Duración del SueñoRESUMEN
Using first-principles calculations, we report the realization of multiferroics in an intrinsic ferroelectric α-Ga2S3 monolayer. Our results show that the presence of intrinsic gallium vacancies, which is the origin of native p-type conductivity, can simultaneously introduce a ferromagnetic ground state and a spontaneous out-of-plane polarization. However, the high switching barrier and thermodynamic irreversibility of the ferroelectric reversal path disable the maintenance of ferroelectricity, suggesting that the defect-free form should be a prerequisite for Ga2S3 to be multiferroic. Through applying strain, the behavior of spontaneous polarization of the pristine α-Ga2S3 monolayer can be effectively regulated, but the non-magnetic ground state does not change. Strikingly, via an appropriate concentration of hole doping, stable ferromagnetism with a high Curie temperature and robust ferroelectricity can be concurrently introduced in the α-Ga2S3 monolayer. Our work provides a feasible method for designing 2D multiferroics with great potential in future device applications.
RESUMEN
Even though organic molecules with designed structures can be assembled into high-capacity electrode materials, only limited functional groups such as -CâO and -CâN- could be designed as high-voltage cathode materials with enough high capacity. Here, we propose a common chemical raw material, trinitroaromatic salt, to have promising potential to develop organic cathode materials with high discharge voltage and capacity through a strong delocalization effect between -NO2 and aromatic ring. Our first-principles calculations show that electrochemical reactions of trinitroaromatic potassium salt C6H2(NO2)3OK are a 6-electron charge-transfer process, providing a high discharge capacity of 606 mAh g-1 and two voltage plateaus of 2.40 and 1.97 V. Electronic structure analysis indicates that the discharge process from C6H2(NO2)3OK to C6H2(NO2Li2)3OK stabilizes oxidized [C6]n+ to achieve a stable conjugated structure through electron delocalization from -NO2 to [C6]n+. The ordered layer structure C6H2(NO2)3OK can provide large spatial pore channels for Li-ion transport, achieving a high ion diffusion coefficient of 3.41 × 10-6 cm2 s-1.
RESUMEN
Fluorescence sensing of enantiomers is a much needed yet very challenging task due to nearly identical chemical and physical properties of the chiral isomers also known as chiral equivalence. In this study, we propose a novel strategy for fluorescence sensing of enantiomers using chiral nanoparticles and their ability to form dynamic assemblies. Fluorescence resonance energy transfer (FRET) in nanoscale assemblies consisting of either L-cysteine- or D-cysteine-modified quantum dots (QDs) and gold nanorods (GNRs) was found to be strongly dependent on traces of cysteine. This occurs due to high sensitivity of dynamic assemblies to the weak internanoparticle interactions that can exponentially increase energy transfer efficiencies from QDs to GNRs. Comprehensive analysis of the fluorescence responses in the two types of chiral nanoscale assemblies enables accurate determination of both concentration and enantiomeric composition of the analyte, i.e., cysteine. The described method can quantify the composition of a chiral sample, even the content of one enantiomer is as low as 10% in the mixture. Exceptional selectivity in respect to D/L-cysteine in comparison to analogous small molecules was observed. Versatility of nanoparticle-nanorod assemblies and tunability of intermolecular interactions in them open the road to adaptation of this sensing platform to other chiral analytes.
Asunto(s)
Cisteína/química , Transferencia Resonante de Energía de Fluorescencia , Nanopartículas/química , Nanotubos/química , Oro/química , Puntos Cuánticos , EstereoisomerismoRESUMEN
The products and mechanisms of the atmospherically and environmentally important reaction, C(2)Cl(3) + NO, are investigated comprehensively by step-scan time-resolved Fourier transform infrared emission spectroscopy and the CCSD(T)/6-311+G(d)//B3LYP/6-311G(d) level of electronic structure calculations. Vibrationally excited products of Cl(2)CO, ClNCO, CCl(3)NCO and NCO have been observed in the IR emission spectra. Cyclic intermediates are found to play important roles leading to the rich variety of the chemical transformations of the reaction. Mainly two competitive reaction pathways are revealed: the four-membered ring intermediate pathway leading to the products Cl(2)CO + ClCN which is essentially barrierless and the bicyclic ring intermediate pathway leading to the product channels of ClNCO + CCl(2,) CCl(3)NCO and CCl(3) + NCO which is rate-limited by a barrier of 42.9 kJ mol(-1) higher than the reactants. By photolyzing the precursor at 248 and 193 nm, respectively, C(2)Cl(3) radicals with different internal energy are produced to observe the product branching ratios as a function of reactant energy. The Cl(2)CO channel via the four-membered ring intermediate pathway is shown to be overwhelmingly dominant at low energy (temperature) but become less important at high energy while the ClNCO and CCl(3)NCO channels via the bicyclic ring intermediate pathway are greatly enhanced and compete effectively. The experimental observation of the products and their branching ratios varying with reactant energy is well consistent with the calculated potential energy profiles.