RESUMO
Inorganic superionic conductors possess high ionic conductivity and excellent thermal stability but their poor interfacial compatibility with lithium metal electrodes precludes application in all-solid-state lithium metal batteries1,2. Here we report a LaCl3-based lithium superionic conductor possessing excellent interfacial compatibility with lithium metal electrodes. In contrast to a Li3MCl6 (M = Y, In, Sc and Ho) electrolyte lattice3-6, the UCl3-type LaCl3 lattice has large, one-dimensional channels for rapid Li+ conduction, interconnected by La vacancies via Ta doping and resulting in a three-dimensional Li+ migration network. The optimized Li0.388Ta0.238La0.475Cl3 electrolyte exhibits Li+ conductivity of 3.02 mS cm-1 at 30 °C and a low activation energy of 0.197 eV. It also generates a gradient interfacial passivation layer to stabilize the Li metal electrode for long-term cycling of a Li-Li symmetric cell (1 mAh cm-2) for more than 5,000 h. When directly coupled with an uncoated LiNi0.5Co0.2Mn0.3O2 cathode and bare Li metal anode, the Li0.388Ta0.238La0.475Cl3 electrolyte enables a solid battery to run for more than 100 cycles with a cutoff voltage of 4.35 V and areal capacity of more than 1 mAh cm-2. We also demonstrate rapid Li+ conduction in lanthanide metal chlorides (LnCl3; Ln = La, Ce, Nd, Sm and Gd), suggesting that the LnCl3 solid electrolyte system could provide further developments in conductivity and utility.
RESUMO
ConspectusProperties of colloidal semiconductor nanocrystals with a single-crystalline structure are largely dominated by their surface structure at an atomic-molecular level, which is not well understood and controlled, due to a lack of experimental tools. However, if viewing the nanocrystal surface as three relatively independent spatial zones (i.e., crystal facets, inorganic-ligands interface, and ligands monolayer), we may approach an atomic-molecular level by coupling advanced experimental techniques and theoretical calculations.Semiconductor nanocrystals of interest are mainly based on compound semiconductors and mostly in two (or related) crystal structures, namely zinc-blende and wurtzite, which results in a small group of common low-index crystal facets. These low-index facets, from a surface-chemistry perspective, can be further classified into polar and nonpolar ones. Albeit far from being successful, the controlled formation of either polar or nonpolar facets is available for cadmium chalcogenide nanocrystals. Such facet-controlled systems offer a reliable basis for studying the inorganic-ligands interface. For convenience, here facet-controlled nanocrystals refer to a special class of shape-controlled ones, in which shape control is at an atomic level, instead of those with poorly defined facets (e.g., typical spheroids, nanorods, etc).Experimental and theoretical results reveal that type and bonding mode of surface ligands on nanocrystals is facet-specific and often beyond Green's classification (X-type, Z-type, and L-type). For instance, alkylamines bond strongly to the anion-terminated (0001) wurtzite facet in the form of ammonium ions, with three hydrogens of an ammonium ion bonding to three adjacent surface anion sites. With theoretically assessable experimental data, facet-ligands pairing can be identified using density functional theory (DFT) calculations. To make the pairing meaningful, possible forms of all potential ligands in the system need to be examined systematically, revealing the advantage of simple solution systems.Unlike the other two spatial zones, the ligands monolayer is disordered and dynamic at an atomic level. Thus, an understanding of the ligands monolayer on a molecular scale is sufficient for many cases. For colloidal nanocrystals stably coordinated with surface ligands, their solution properties are dictated by the ligands monolayer. Experimental and theoretical results reveal that solubility of a nanocrystal-ligands complex is an interplay between the intramolecular entropy of the ligands monolayer and intermolecular interactions of the ligands/nanocrystals. By introducing entropic ligands, solubility of nanocrystal-ligands complexes can be universally boosted by several orders of magnitude, i.e., up to >1 g/mL in typical organic solvents. Molecular environment in the pseudophase surrounding each nanocrystal plays a critical role in its chemical, photochemical, and photophysical properties.For some cases, such as the synthesis of high-quality nanocrystals, all three spatial zones of the nanocrystal surface must be taken into account. By optimizing nanocrystal surface at an atomic-molecular level, semiconductor nanocrystals with monodisperse size and facet structure become available recently through either direct synthesis or afterward facet reconstruction, implying full realization of their size-dependent properties.
RESUMO
The meta-analysis aimed to assess and compare the effect of closed-incision negative pressure wound (NPW) treatment in vascular surgery. Using dichotomous or contentious random or fixed effect models, the outcomes of this meta-analysis were examined, and the odds Ratio (OR) and the mean difference (MD) with 95% confidence intervals (CIs) were computed. Ten examinations from 2017 to 2022 were enrolled for the present meta-analysis, including 2082 personals with vascular surgery. Closed-incision NPW treatment had significantly lower infection rates (OR, 0.39; 95% CI, 0.30-0.51, p < 0.001), grade I infection rates (OR, 0.33; 95% CI, 0.20-0.52, p < 0.001), grade II infection rates (OR, 0.39; 95% CI, 0.21-0.71, p = 0.002), and grade III infection rates (OR, 0.31; 95% CI, 0.13-0.73, p = 0.007), and surgical re-intervention (OR, 0.49; 95% CI, 0.25-0.97, p = 0.04) compared to control in personal with vascular surgery. However, no significant differences were found between closed-incision NPW treatment and control in the 30-day mortality (OR, 0.54; 95% CI, 0.29-1.00, p = 0.05), antibiotic treatment (OR, 0.53; 95% CI, 0.24-1.19, p = 0.12), and length of hospital stay (MD, -0.02; 95% CI, -0.24-0.19, p = 0.83) in personnel with vascular surgery. The examined data revealed that closed-incision NPW treatment had significantly lower infection rates, grade I infection rates, grade II infection rates, and grade III infection rates, surgical re-intervention, however, there were no significant differences in 30-day mortality, antibiotic treatment, or length of hospital stay compared to control group with vascular surgery. Yet, attention should be paid to its values since some comparisons had a low number of selected studies.
Assuntos
Tratamento de Ferimentos com Pressão Negativa , Ferida Cirúrgica , Humanos , Infecção da Ferida Cirúrgica/epidemiologia , Infecção da Ferida Cirúrgica/terapia , Ferida Cirúrgica/terapia , Procedimentos Cirúrgicos Vasculares , AntibacterianosRESUMO
One of the central focuses in self-assembly is precisely controlling the self-assembly pathway so that the target molecules can be produced exclusively. Trans-1,2-cyclohexanediamine contains two amino units that form a 60° angle when projected on a plane. This angle naturally favors the formation of triangular products in most cases when trans-1,2-cyclohexanediamine is used as a bisamino building block in the synthesis of macrocycles and tubes. Here, we synthesized a slightly bent tetraformyl precursor bearing a central dibenzothiophene moiety, whose 3,7-positions are functionalized with two m-phthalaldehyde units. We observed that combining this tetraformyl building block with trans-1,2-cyclohexanediamine yielded a quadrangular tube when the concentrations of the precursors were relatively high. Both experimental measurements and theoretical calculations indicate that the formation of this unlikely occurring quadrangular product was driven by the intramolecular C-H···π interactions between the dibenzothiophene building blocks within the tube framework. This driving force, however, was disturbed in the triangular tube, a smaller counterpart whose formation was considered previously much more thermodynamically favored. These results improved our fundamental understanding on how to create those products whose syntheses are considered difficult or impossible, by modulating the intramolecular driving forces.
RESUMO
How Nature synthesizes enantiomerically pure substances from achiral or racemic resources remains a mystery. In this study, we aimed to emulate this natural phenomenon by constructing chiral tetrahedral cages through self-assembly, achieved by condensing two achiral compounds-a trisamine and a trisaldehyde. The occurrence of intercomponent CHâ â â π interactions among the phenyl building blocks within the cage frameworks results in twisted conformations, imparting planar chirality to the tetrahedrons. In instances where the trisaldehyde precursor features electron-withdrawing ester side chains, we observed that the intermolecular CHâ â â π forces are strong enough to prevent racemization. To attain enantioselective self-assembly, a chiral amine was introduced during the imine formation process. The addition of three equivalents of chiral amino mediator to one equivalent of the achiral trisaldehyde precursor formed a trisimino intermediate. This chiral compound was subsequently combined with the achiral trisamino precursor, leading to an imine exchange reaction that releasing the chiral amino mediator and formation of the tetrahedral cage with an enantiomeric excess (ee) of up to 75 %, exclusively composed of achiral building blocks. This experimental observation aligns with theoretical calculations based on the free energies of related cage structures. Moreover, since the chiral amine was not consumed during the imine exchange cycle, it enabled the enantioselective self-assembly of the tetrahedral cage for multiple cycles when new batches of the achiral trisaldehyde and trisamino precursors were successively added.
RESUMO
Synthesis of colloidal semiconductor nanocrystals with defined facet structures is challenging, though such nanocrystals are essential for fully realizing their size-dependent optical and optoelectronic properties. Here, for the mostly developed colloidal wurtzite CdSe/CdS core/shell nanocrystals, facet reconstruction is investigated under typical synthetic conditions, excluding nucleation, growth, and interparticle ripening. Within the reaction time window, two reproducible sets of facetsâeach with a specific group of low-index facetsâcan be reversibly reconstructed by switching the ligand system, indicating thermodynamic stability of each set. With a unique <0001> axis, atomic structures of the low-index facets of wurtzite nanocrystals are diverse. Experimental and theoretical studies reveal that each facet in a given set is paired with a common ligand in the solution, namely, either fatty amine and/or cadmium alkanoate. The robust bonding modes of ligands are found to be strongly facet-dependent and often unconventional, instead of following Green's classification. Results suggest that facet-controlled nanocrystals can be synthesized by optimal facet-ligand pairing either in synthesis or after-synthesis reconstruction, implying semiconductor nanocrystal formation with size-dependent properties down to an atomic level.
RESUMO
BACKGROUND: An accurate recurrence risk assessment system and surveillance strategy for hepatoid adenocarcinoma of the stomach (HAS) remain poorly defined. This study aimed to develop a nomogram to predict postoperative recurrence of HAS and guide individually tailored surveillance strategies. METHODS: The study enrolled all patients with primary HAS who had undergone curative-intent resection at 14 institutions from 2004 to 2019. Clinicopathologic variables with statistical significance in the multivariate Cox regression were incorporated into a nomogram to build a recurrence predictive model. RESULTS: The nomogram of recurrence-free survival (RFS) based on independent prognostic factors, including age, preoperative carcinoembryonic antigen, number of examined lymph nodes, perineural invasion, and lymph node ratio, achieved a C-index of 0.723 (95% confidence interval [CI], 0.674-0.772) in the whole cohort, which was significantly higher than those of the eighth American Joint Committed on Cancer (AJCC) staging system (C-index, 0.629; 95% CI, 0.573-0.685; P < 0.001). The nomogram accurately stratified patients into low-, middle-, and high-risk groups of postoperative recurrence. The postoperative recurrence risk rates for patients in the middle- and high-risk groups were respectively 3 and 10 times higher than for the low-risk group. The patients in the middle- and high-risk groups showed more recurrence and metastasis, particularly multiple site metastasis, within 36 months after the operation than those in the low-risk group (low, 2.2%; middle, 8.6%; high, 24.0%; P = 0.003). CONCLUSIONS: The nomogram achieved good prediction of postoperative recurrence for the patients with HAS after radical resection. For the middle- and high-risk patients, more active surveillance and targeted examination methods should be adopted within 36 months after the operation, particularly for liver and multiple metastases.
Assuntos
Adenocarcinoma , Neoplasias Gástricas , Humanos , Nomogramas , Prognóstico , Adenocarcinoma/cirurgia , Adenocarcinoma/patologia , Estadiamento de Neoplasias , Estudos Retrospectivos , Neoplasias Gástricas/patologia , Recidiva Local de Neoplasia/patologiaRESUMO
BACKGROUND: The aim of this retrospective matched-paired cohort study was to clarify the effectiveness of preserving the vagus nerve in totally laparoscopic radical distal gastrectomy (TLDG). METHODS: One hundred eighty-three patients with gastric cancer who underwent TLDG between February 2020 and March 2022 were included and followed up. Sixty-one patients with preservation of the vagal nerve (VPG) in the same period were matched (1:2) to conventional sacrificed (CG) cases for demographics, tumor characteristics, and tumor node metastasis stage. The evaluated variables included intraoperative and postoperative indices, symptoms, nutritional status, and gallstone formation at 1 year after gastrectomy between the two groups. RESULTS: Although the operation time was significantly increased in the VPG compared with the CG (198.0 ± 35.2 vs. 176.2 ± 35.2 min, P < 0.001), the mean time of gas passage in the VPG was significantly lower than that in the CG (68.1 ± 21.7 h vs. 75.4 ± 22.6 h, P = 0.038). The overall postoperative complication rate was similar between the two groups (P = 0.794). There was no statistically significant difference between the two groups hospital stay, total number of harvested lymph nodes, and mean number of examined lymph nodes at each station. During follow-up, the morbidity of gallstones or cholecystitis (8.2% vs. 20.5%, P = 0.036), chronic diarrhea (3.3% vs. 14.8%, P = 0.022), and constipation (4.9% vs. 16.4%, P = 0.032) were significantly lower in the VPG than in the CG in this study. Moreover, injury to the vagus nerve was found to be an independent risk factor for gallstone formation or cholecystitis and chronic diarrhea in univariate analysis and multivariate analysis. CONCLUSION: The vagus nerve plays an imperative role in gastrointestinal motility, and hepatic and celiac branch preservation mainly exerts efficacy and safety in patients who undergo TLDG.
Assuntos
Colecistite , Cálculos Biliares , Laparoscopia , Neoplasias Gástricas , Humanos , Estudos Retrospectivos , Estudos de Coortes , Cálculos Biliares/cirurgia , Gastrectomia/efeitos adversos , Neoplasias Gástricas/cirurgia , Neoplasias Gástricas/patologia , Laparoscopia/efeitos adversos , Nervo Vago/patologia , Colecistite/cirurgia , Diarreia/cirurgia , Resultado do TratamentoRESUMO
BACKGROUND: Roux-en-Y (R-Y) anastomoses have been widely used in distal gastrectomy, while the incidence of Roux stasis syndrome remains common. Uncut R-Y anastomosis maintains the neuromuscular continuity, thus avoiding the ectopic pacemaker of the Roux limb and reducing the occurrence of Roux stasis. However, retrospective studies of Uncut R-Y anastomosis remain scarce and randomized controlled trials have not been reported. METHODS: We conducted a randomized controlled trial to compare the surgical safety, nutritional status, and postoperative quality of life (QOL) between uncut and classic Roux-en-Y (R-Y) reconstruction patients. Patients with Stage I gastric cancer were randomly enrolled and underwent laparoscopic distal gastrectomy followed by uncut or classic R-Y reconstruction. Body mass index and blood test were used to evaluate the nutritional status. QOL was evaluated using European Organization for Research and Treatment of Cancer QOL Questionnaire (STO22) and laboratory examinations at postoperative month (POM) 3, 6, 9, and 12. Computed tomography scanning was used to evaluate the skeletal muscle index (SMI) at POM 6 and 12. Endoscopy was performed at POM 12. RESULTS: Operation time, blood loss, time to recovery, complication morbidities, and overall survival were similar between the two groups. Compared with the classic R-Y group, the uncut R-Y group displayed a significantly decreased QOL at POM 9, possibly due to loop recanalization, determined to be occupied 34.2% of the uncut R-Y group. Post-exclusion of recanalization, the QOL was still higher in the classic R-Y group than in the uncut R-Y group, despite their hemoglobin and total protein levels being better than those in the classic R-Y group. Preoperative pre-albumin level and impaired fasting glycemia significantly correlated with the postoperative recanalization. CONCLUSION: We found no significant benefit of uncut over classic R-Y reconstruction which challenges the superiority of the uncut R-Y reconstruction. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02644148.
Assuntos
Neoplasias Gástricas , Humanos , Neoplasias Gástricas/cirurgia , Neoplasias Gástricas/complicações , Qualidade de Vida , Gastrectomia/métodos , Estudos Retrospectivos , Estudos Prospectivos , Resultado do Tratamento , Anastomose em-Y de Roux/métodos , Complicações Pós-Operatórias/epidemiologia , Complicações Pós-Operatórias/etiologia , Complicações Pós-Operatórias/cirurgia , Ensaios Clínicos Controlados Aleatórios como AssuntoRESUMO
Objective: To compare the clinical efficacy and safety of laparoscopic common bile duct exploration and endoscopic retrograde cholangiopancreatography in the treatment of bile duct stones, and to analyze the related factors influencing postoperative acute pancreatitis. Methods: From March 2017 to June 2021, we recruited patients with bile duct stones to our study: 175 patients undergoing endoscopic retrograde cholangiopancreato-graphy and 147 patients undergoing laparoscopic common bile duct exploration. The operative time, intraoperative blood loss, conversion to laparotomy, postoperative exhaust time, hospitalization time, liver function before and after the operation, and the incidence of adverse events were compared. Logistic regression analysis was used to analyze the related factors influencing postoperative acute pancreatitis. Results: All patients were operated on successfully, with no conversion to laparotomy. Operative time, postoperative exhaust time, and hospitalization time were shorter, intraoperative blood loss was lower, and aspartate aminotransferase and alanine aminotransferase were higher in the endoscopic retrograde cholangiopancreato-graphy group compared with the laparoscopic common bile duct exploration group (P < .05). The endoscopic retrograde cholangiopancreatography group had a higher incidence of adverse events than the laparoscopic common bile duct exploration group (P < .05). After logistic regression analysis, white blood cell concentration, operative time, intraoperative blood loss, previous history of pancreatic disease, and endoscopic retrograde cholangiopancreatography operation all independently influenced the occurrence of acute pancreatitis. Conclusion: Laparoscopic common bile duct exploration is our first choice for patients with bile duct stones who have no history of abdominal surgery, cardiac or pulmonary valve insufficiency, bile duct stenosis, and poor duodenal papilla function, as it can reduce the occurrence of postoperative complications and shorten rehabilitation. Further investigation of the factors that independently caused postoperative acute pancreatitis after stone removal is warranted.
RESUMO
BACKGROUND: Tyrosinase is the key enzyme involved in enzymatic browning of plant-derived foods. Inhibition of tyrosinase activity contributes to the control of food browning. Due to safety regulations or other issues, most identified tyrosinase inhibitors are not suitable for practical use. Therefore, it is necessary to search for novel tyrosinase inhibitors. In this study, the anti-tyrosinase activity and mechanism of albendazole and 2-(2-aminophenyl)-1H-benzimidazole (2-2-A-1HB) were investigated through ultraviolet-visible absorption spectroscopy, fluorescence spectra, molecular docking, and molecular dynamic (MD) simulation. The anti-browning effect of albendazole on fresh-cut apples was then elucidated. RESULTS: Albendazole and 2-2-A-1HB were both efficient tyrosinase inhibitors with IC50 of 51 ± 1.5 and 128 ± 1.3 µmol L-1 , respectively. Albendazole suppressed tyrosinase non-competitively and formed tyrosinase-albendazole complex statically. Hydrogen bond and hydrophobic interaction were major driving forces in stabilizing the tyrosinase-albendazole complex. While 2-2-A-1HB inhibited the enzyme competitively and quenched its intrinsic fluorescence through a static mechanism, it generated strong binding affinity with tyrosinase through hydrophobic interaction. MD simulations further validated that albendazole/2-2-A-1HB could form stable complexes with tyrosinase and loosened its basic framework structure, leading to a change in secondary structure and conformation. In addition, albendazole could delay the browning of fresh-cut apples by inhibiting the activity of polyphenol oxidase, peroxidase and phenylalanine ammonia-lyase, and reducing the oxidation of phenolic compounds. CONCLUSION: This research might provide a deep view of tyrosinase inhibition by benzimidazole derivatives and a theoretical basis for developing albendazole as a potential fresh-keeping agent. © 2023 Society of Chemical Industry.
Assuntos
Malus , Monofenol Mono-Oxigenase , Albendazol/farmacologia , Simulação de Acoplamento Molecular , Relação Estrutura-Atividade , Malus/química , Benzimidazóis/farmacologia , Inibidores Enzimáticos/químicaRESUMO
As popular mixed quantum-classical dynamics methods, trajectory surface hopping and Ehrenfest mean field have been widely utilized to simulate nonadiabatic dynamics. Recently, we have proposed the branching-corrected surface hopping and the branching-corrected mean field methods, both of which closely reproduce the exact quantum dynamics in a series of standard scattering models. Here, the mixed surface hopping and mean field with branching correction (BCSHMF) is presented as a unified framework of mixed quantum-classical dynamics. As benchmarked in thousands of diverse three-level and four-level scattering models, BCSHMF achieves high reliability and flexibility, implying that surface hopping and mean field are compatible with each other in nature, and trajectory branching is essential for the mixed quantum-classical description of nonadiabatic dynamics.
RESUMO
We report a surface hopping approach in which the implemented linear vibronic coupling Hamiltonian is constructed and the electronic wavefunction is propagated in the reciprocal space. The parameters of the linear vibronic coupling model, including onsite energies, phonon frequencies, and electron-phonon couplings, are calculated with density-functional theory and density-functional perturbation theory and interpolated in fine sampling points of the Brillouin zone with maximally localized Wannier functions. Using this approach, we studied the relaxation dynamics of the photo-excited hot carrier in a one-dimensional periodic carbon chain. The results show that the completeness of the number of Hilbert space k points and the number of phonon q points plays an important role in the hot carrier relaxation processes. By calculating the relaxation times of hot carriers under different reciprocal space sampling and extrapolating with the stretched-compressed exponential function, the relaxation times of hot electrons and holes in the quasi-continuous energy band are obtained. By considering the feedback effect in the hopping processes and analyzing the time-dependent phonon energy in different normal modes, we found that the long-wave longitudinal optical phonons play a major role in the relaxation dynamics of hot electrons and holes. We, therefore, provided herein an efficient and accurate approach for modeling the photophysical processes in periodic solid-state material systems.
RESUMO
Disordered or even seemingly amorphous, donor-acceptor type, conjugated copolymers with high charge-carrier mobility have emerged as a new class of functional materials, where transport along the conjugated backbone is key. Here, we report on non-adiabatic molecular dynamics simulations of charge-carrier transport along chains of poly (indacenodithiophene-co-benzothiadiazole), within a model Hamiltonian parameterized against first-principles calculations. We predict thermally activated charge transport associated with a slightly twisted ground-state conformation, on par with experimental results. Our results also demonstrate that the energy mismatch between the hole on the donor vs the acceptor units of the copolymer drives localization of the charge carriers and limits the intra-chain charge-carrier mobility. We predict that room-temperature mobility values in excess of 10 cm2 V-1 s-1 can be achieved through proper chemical tuning of the component monomer units.
RESUMO
We present a new algorithm of the branching corrected mean field (BCMF) method for nonadiabatic dynamics [J. Xu and L. Wang, J. Phys. Chem. Lett. 11, 8283 (2020)], which combines the key advantages of the two existed algorithms, i.e., the deterministic BCMF algorithm based on weights of trajectory branches (BCMF-w) and the stochastic BCMF algorithm with random collapse of the electronic wavefunction (BCMF-s). The resulting mixed deterministic-stochastic BCMF algorithm (BCMF-ws) is benchmarked in a series of standard scattering problems with potential wells on the excited-state surfaces, which are common in realistic systems. In all investigated cases, BCMF-ws holds the same high accuracy while the computational time is reduced about two orders of magnitude compared to the original BCMF-w and BCMF-s algorithms, thus promising for nonadiabatic dynamics simulations of general systems.
RESUMO
Chemical systems with external control capability and self-recoverability are promising since they can avoid additional chemical or energy imposition during the working process. However, it remains challenging to employ such a nonequilibrium method for the engineering of optoelectronic function and for visualization. Here, we report a functional molecule that can undergo intense conformational regulation upon photoexcitation. It enables a dynamical change in hydrophobicity and a follow-up molecular aggregation in aqueous media, accordingly leading to an aggregation-induced phosphorescence (AIP) behavior. This successive performance is self-recoverable, allowing a rapid (second-scale cycle) and long-standing (>103 cycles) flicker ability under rhythmical control of the AIP. Compared with traditional bidirectional manipulations, such monodirectional photocontrol with spontaneous reset profoundly enhances the operability while mostly avoiding possible side reactions and fatigue accumulation. Furthermore, this material can serve as a type of luminescent probe for dynamically strengthening visualization in bioimaging.
Assuntos
Luminescência , Difusão Dinâmica da Luz , Células HeLa , Humanos , Conformação MolecularRESUMO
Zinc-blende CdS nanoplatelets with atomically flat and very large {100} basal planes terminated solely by one type of element (either Cd or S atoms) are synthesized. Optical spectroscopy, X-ray diffraction, X-ray absorption, and transmission electron microscopy confirm that the surface structures of newly developed S-terminated CdS nanoplatelets are at least as well-defined as the original Cd-terminated nanoplatelets. Band gaps of the nanoplatelets are found to depend on not only the quantum-confined dimension (thickness) but also the nature of the surface termination. The facet structure dictates the packing of the ligands (carboxylate for Cd-terminated nanoplatelets and alkyl for S-terminated nanoplatelets), which causes a difference in the lattice strain and significantly affects the optical spectral width. Experimental and theoretical results reveal that engineering the exciton spatial distribution by the tailored synthesis of semiconductor nanocrystals with a precisely controlled surface structure is fully possible, which should open a new door for delivering the long-promised potential of semiconductor nanocrystals.
RESUMO
Allatostatin C (PISCF/AST) is a neuropeptide gene that affects juvenile hormone (JH) synthesis in the corpora allata. Juvenile hormone acid O-methyltransferase (JHAMT) is a key gene in the JH biosynthetic pathway. In this study, two genes encoding DaAST and DaJHAMT were cloned. Both DaAST and DaJHAMT were expressed in the larvae, pupae and adults of Chinese white pine beetle (Dendroctonus armandi), and highly expressed in the head and the gut. The expression of the two genes was induced by JH analog (JHA) methoprene and the functions of the two genes were then investigated by RNAi. Considering the role of hormones in metamorphosis, JHA significantly induced DaAST and DaJHAMT in the larval stage. DaAST knockdown in larvae, pupae and adults significantly increased the DaJHAMT mRNA levels. Moreover, knockdown of DaAST instead of DaJHAMT increased pupae mortality and the abnormal rate of emergence morphology and reduced emergence rates. However, knockdown of DaJHAMT instead of DaAST significantly reduced frontalin biosynthesis in adult males. The results showed that DaAST acts as an allatostatin and inhibits JH biosynthesis, and that JHAMT is a key regulatory enzyme for JH synthesis in the D. armandi.
Assuntos
Hormônios Juvenis , Neuropeptídeos , Animais , Corpora Allata/metabolismo , Hormônios Juvenis/metabolismo , Larva/metabolismo , Masculino , Metiltransferases/genética , Metiltransferases/metabolismo , Neuropeptídeos/genética , Neuropeptídeos/metabolismo , Pupa/genética , Pupa/metabolismoRESUMO
BACKGROUND: A novel type of noncoding RNA, circRNA has been reported to participate in the occurrence and development of diseases through many mechanisms. The MAPK pathway is a common signal transduction pathway involved in cell proliferation, inflammation and apoptosis and plays a particularly important role in cancers. However, the role of circRNAs related to the MAPK pathway in gastric cancer has not been explored. METHODS: A bioinformatics analysis was performed to profile and identify the circRNAs involved in the MAPK pathway in gastric cancer. The tumor-suppressive role of circMAPK1 was confirmed both in vitro and in vivo. Mass spectrometry, Western blot and immunofluorescence staining assays were used to validate the existence and expression of MAPK1-109aa. The molecular mechanism of circMAPK1 was investigated by mass spectrometry and immunoprecipitation analyses. RESULTS: In this study, we identified that circMAPK1 (hsa_circ_0004872) was downregulated in gastric cancer tissues compared with adjacent normal tissues. Importantly, lower circMAPK1 expression predicted poor survival in GC patients. CircMAPK1 inhibited the proliferation and invasion of gastric cancer cells in vitro and in vivo. Next, we found that circMAPK1 encoded a novel protein with 109 amino acids in length. Through a series of functional experiments, we confirmed that circMAPK1 exerted a tumor-suppressing effect via the encoded protein MAPK1-109aa. Mechanistically, the tumor suppressor MAPK1-109aa inhibited the phosphorylation of MAPK1 by competitively binding to MEK1, thereby suppressing the activation of MAPK1 and its downstream factors in MAPK pathway. CONCLUSIONS: Our study revealed that circMAPK1 inhibits the malignant biological behavior of gastric cancer cells through its encoded protein MAPK1-109aa. More importantly, circMAPK1 is a favorable predictor for gastric cancer patients and may provide a new therapeutic target in the treatment of gastric cancer.
Assuntos
Biomarcadores Tumorais , Sistema de Sinalização das MAP Quinases , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , RNA Circular/genética , Neoplasias Gástricas/genética , Neoplasias Gástricas/metabolismo , Adulto , Idoso , Sequência de Aminoácidos , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células/genética , Transformação Celular Neoplásica/genética , Transformação Celular Neoplásica/metabolismo , Suscetibilidade a Doenças , Feminino , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Humanos , Masculino , Pessoa de Meia-Idade , Proteína Quinase 1 Ativada por Mitógeno/química , Metástase Neoplásica , Estadiamento de Neoplasias , Fosforilação , Neoplasias Gástricas/patologia , Carga TumoralRESUMO
Since the seminal work of Tully [J. Chem. Phys. 93, 1061 (1990)], two-level scattering models have been extensively adopted as the standard benchmark systems to assess the performance of different trajectory surface hopping methods for nonadiabatic dynamics simulations. Here, we extend the branching and phase corrections to multilevel systems and combine them with both the traditional fewest switches surface hopping (FSSH) and its variant global flux surface hopping (GFSH) algorithms. To get a comprehensive evaluation of the proposed methods, we construct a series of more challenging and diverse three-level and four-level scattering models and use exact quantum solutions as references. Encouragingly, both FSSH and GFSH with the branching and phase corrections produce excellent and nearly identical results in all investigated systems, indicating that the new surface hopping methods are robust to describe multilevel problems and the reliability is insensitive to the definition of self-consistent hopping probabilities in the adiabatic representation. Furthermore, the branching correction is found to be especially important when dealing with strongly repulsive potential energy surfaces, which are common in realistic systems, thus promising for general applications.