RESUMEN
Single-site catalysts (SSCs) achieve a high catalytic performance through atomically dispersed active sites. A challenge facing the development of SSCs is aggregation of active catalytic species. Reducing the loading of these sites to very low levels is a common strategy to mitigate aggregation and sintering; however, this limits the tools that can be used to characterize the SSCs. Here we report a sintering-resistant SSC with high loading that is achieved by incorporating Anderson-Evans polyoxometalate clusters (POMs, MMo6O24, M = Rh/Pt) within NU-1000, a Zr-based metal-organic framework (MOF). The dual confinement provided by isolating the active site within the POM, then isolating the POMs within the MOF, facilitates the formation of isolated noble metal sites with low coordination numbers via exsolution from the POM during activation. The high loading (up to 3.2 wt %) that can be achieved without sintering allowed the local structure transformation in the POM cluster and the surrounding MOF to be evaluated using in situ X-ray scattering with pair distribution function (PDF) analysis. Notably, the Rh/Pt···Mo distance in the active catalyst is shorter than the M···M bond lengths in the respective bulk metals. Models of the active cluster structure were identified based on the PDF data with complementary computation and X-ray absorption spectroscopy analysis.
RESUMEN
Here, ultrasmall SiO2 nanoparticles (u-SiO2 NPs, <5 nm) with obvious electrochemiluminescence (ECL) phenomenon, which was absent for conventional silica nanoparticles (c-SiO2 NPs), were reported. In a finite ultrasmall volume, the u-SiO2 NPs exhibited increasing ground state energy and higher optical absorption strength due to the electron-hole confinement model and favored catalyzing the reaction through the rapid diffusion of bulk charge, resulting in apparent ECL emission. Then, Zn2+-induced u-SiO2 nanoaggregates (Zn/u-SiO2-Ov nAGG) were synthesized and exhibited improved ECL performance via multipath surface state adjustment of u-SiO2 from several aspects, including aggregation-induced ECL, the generation of oxygen vacancy (Ov), and more positive surface charge. In addition, an ECL biosensor was constructed for ultrasensitive human immunodeficiency virus-related deoxyribonucleic acid detection from 100 aM to 1 nM with a low limit of 50.48 aM, combining the ECL luminescence of Zn/u-SiO2-Ov nAGG with three-dimensional DNA nanomachine-mediated multioutput amplification for enhanced accuracy and sensitivity compared to the single-output method. Therefore, exploring the ECL of ultrasmall nanoparticles via the adjustment of size and surface state provided a valuable indication to a wider investigation and application of novel ECL materials for clinical diagnostic.
Asunto(s)
ADN Viral , Técnicas Electroquímicas , Mediciones Luminiscentes , Nanopartículas , Dióxido de Silicio , Propiedades de Superficie , Dióxido de Silicio/química , Nanopartículas/química , Técnicas Electroquímicas/métodos , Mediciones Luminiscentes/métodos , ADN Viral/análisis , Tamaño de la Partícula , Técnicas Biosensibles/métodos , VIH , Humanos , Límite de DetecciónRESUMEN
Diquat dibromide (DQ) is a globally used herbicide in agriculture, and its overuse poses an important public health issue, including male reproductive toxicity in mammals. However, the effects and molecular mechanisms of DQ on testes are limited. In vivo experiments, mice were intraperitoneally injected with 8 or 10â¯mg/kg/ day of DQ for 28 days. It has been found that heme oxygenase-1 (HO-1) mediates DQ-induced ferroptosis in mouse spermatogonia, thereby damaging testicular development and spermatogenesis. Histopathologically, we found that DQ exposure caused seminiferous tubule disorders, reduced germ cells, and increased sperm malformation, in mice. Reactive oxygen species (ROS) staining of frozen section and transmission electron microscopy (TEM) displayed DQ promoted ROS generation and mitochondrial morphology alterations in mouse testes, suggesting that DQ treatment induced testicular oxidative stress. Subsequent RNA-sequencing further showed that DQ treatment might trigger ferroptosis pathway, attributed to disturbed glutathione metabolism and iron homeostasis in spermatogonia cells in vitro. Consistently, results of western blotting, measurements of MDA and ferrous iron, and ROS staining confirmed that DQ increased oxidative stress and lipid peroxidation, and accelerated ferrous iron accumulation both in vitro and in vivo. Moreover, inhibition of ferroptosis by deferoxamine (DFO) markedly ameliorated DQ-induced cell death and dysfunction. By RNA-sequencing, we found that the expression of HO-1 was significantly upregulated in DQ-treated spermatogonia, while ZnPP (a specific inhibitor of HO-1) blocked spermatogonia ferroptosis by balancing intracellular iron homeostasis. In mice, administration of the ferroptosis inhibitor ferrostatin-1 effectively restored the increase of HO-1 levels in the spermatogonia, prevented spermatogonia death, and alleviated the spermatogenesis disorders induced by DQ. Overall, these findings suggest that HO-1 mediates DQ-induced spermatogonia ferroptosis in mouse testes, and targeting HO-1 may be an effective protective strategy against male reproductive disorders induced by pesticides in agriculture.
Asunto(s)
Diquat , Ferroptosis , Hemo-Oxigenasa 1 , Herbicidas , Especies Reactivas de Oxígeno , Espermatogonias , Testículo , Animales , Masculino , Ferroptosis/efectos de los fármacos , Ratones , Espermatogonias/efectos de los fármacos , Espermatogonias/patología , Hemo-Oxigenasa 1/metabolismo , Hemo-Oxigenasa 1/genética , Testículo/efectos de los fármacos , Testículo/patología , Diquat/toxicidad , Herbicidas/toxicidad , Especies Reactivas de Oxígeno/metabolismo , Estrés Oxidativo/efectos de los fármacos , Espermatogénesis/efectos de los fármacos , Proteínas de la MembranaRESUMEN
Excessive phosphorus in aqueous solutions can cause eutrophication, which can harm aquatic organisms and pose a risk to the safety of drinking water for humans. The Chitosan/Polyacrylamide/Lanthanum (CS/PAM/La) hydrogel was designed to get rid of phosphate from aqueous solutions. La (III) was used to enhance the capacity of adsorption of CS. Polyacrylamide was used to enhance the mechanical properties of CS. The results showed that the adsorption capacity of CS/PAM/La hydrogel for phosphate was increased compared with that of CS. When pH of 5.0, the adsorption capacity was 80.07 mg-P/g. In addition, after five adsorption and desorption cycles, the adsorption efficiency remained above 90%. The mechanism of phosphate adsorption on CS/PAM/La material was analyzed using a mass transfer factor model (MTF) and the possible structure of CS/PAM/La hydrogel was calculated by density functional theory calculation (DFT). The application of CS/PAM/La composite hydrogel for removal of phosphate from actual wastewater was investigated, and the results met the requirement of national standard.
Asunto(s)
Resinas Acrílicas , Quitosano , Hidrogeles , Lantano , Fósforo , Aguas Residuales , Contaminantes Químicos del Agua , Aguas Residuales/química , Quitosano/química , Adsorción , Hidrogeles/química , Fósforo/química , Lantano/química , Resinas Acrílicas/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodosRESUMEN
This research investigated the relationships between school climates and bullying behaviors in Chinese adolescents, and tested the mediating effect of prosocial tendency according to the seesaw effect. School climates were operationalized using three constructs: subjective diversity of student development goals, teacher support, and peer trust. Bullying behaviors included traditional (i.e., physical, nonphysical, and relational) and cyber bullying behaviors. We recruited 538 adolescents from three schools in Beijing, China (286 girls, 252 boys; average age = 12.47) and asked them to fill out the surveys measuring school climates and prosocial tendency at the outset and to report school bullying behaviors three months later. The results showed that subjective diversity of student development goals and peer trust were directly associated with less cyber bullying behavior. Moreover, teacher support and peer trust were indirectly associated with less traditional bullying behaviors via prosocial tendency. Our findings extend the existing literature on the relationships between school climates and bullying behaviors by incorporating different types of bullying behaviors, concentrating on Chinese adolescents from a cultural viewpoint, and tapping into the underlying mechanism via revealing prosocial tendency as a mediator. Theoretical and empirical contributions of this study, as well as practical implications are discussed.
Asunto(s)
Conducta del Adolescente , Acoso Escolar , Grupo Paritario , Instituciones Académicas , Humanos , Femenino , Masculino , Adolescente , Acoso Escolar/estadística & datos numéricos , China , Niño , Estudiantes/psicología , Conducta Social , Confianza/psicología , Ciberacoso/estadística & datos numéricos , Ciberacoso/psicología , Pueblos del Este de AsiaRESUMEN
SCOPE: Isorhamnetin is a natural flavonoid with various pharmacological activities, which can be widely and continuously ingested by humans and animals through their daily diet. The aim of this study is to explore the benefits and molecular mechanisms of isorhamnetin on oocyte maturation. METHODS AND RESULTS: Oocytes are incubated with isorhamnetin (5, 10, 20, and 30 µM) for 44 h. Isorhamnetin (10 µM) increases the polar body extrusion rate of oocytes. Furthermore, isorhamnetin alleviates oxidative stress by inhibiting reactive oxygen species levels and stimulating SOD2 protein expression. The changes in intracellular mitochondrial autophagy and apoptosis-related proteins (Bcl-2, Bax/Bcl-2, and C-Casp3) indicate that isorhamnetin inhibits oocyte apoptosis. Isorhamnetin inhibits endoplasmic reticulum stress by reducing the protein expression of CHOP and GRP78 and improving the normal distribution rate of endoplasmic reticulum. Mechanistic studies show that isorhamnetin activates the PI3K/Akt signaling pathway. CONCLUSION: Isorhamnetin promotes oocyte maturation by inhibiting oxidative stress, mitochondrial dysregulation, apoptosis, and endoplasmic reticulum stress, which have important potential for improving oocyte quality and treating female infertility.
Asunto(s)
Oocitos , Quercetina , Transducción de Señal , Animales , Femenino , Ratones , Apoptosis/efectos de los fármacos , Chaperón BiP del Retículo Endoplásmico , Estrés del Retículo Endoplásmico/efectos de los fármacos , Mitocondrias/efectos de los fármacos , Mitocondrias/metabolismo , Oocitos/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Fosfatidilinositol 3-Quinasas/metabolismo , Proteínas Proto-Oncogénicas c-akt/metabolismo , Quercetina/farmacología , Quercetina/análogos & derivados , Especies Reactivas de Oxígeno/metabolismo , Transducción de Señal/efectos de los fármacos , Superóxido Dismutasa/metabolismoRESUMEN
Background: Scrub typhus, caused by the Orientia tsutsugamushi (Ot), is a widespread vector-borne disease transmitted by chigger mites. Hemophagocytic lymphohistiocytosis (HLH) is considered to be one of the potentially severe complications. The diagnosis of scrub typhus-associated HLH may be overlooked due to the non-specific clinical characteristics and the absence of pathognomonic eschar. Case presentation: We obtained clinical data from two patients in the South of Sichuan, China. The first case involved a 6-year-old girl who exhibited an unexplained fever and was initially diagnosed with sepsis, HLH, and pulmonary infection. The other patient presented a more severe condition characterized by multiple organ dysfunction and was initially diagnosed with septic shock, sepsis, HLH, acute kidney injury (AKI), and pulmonary infection. At first, a specific examination for scrub typhus was not performed due to the absence of a characteristic eschar. Conventional peripheral blood cultures yielded negative results in both patients, and neither of them responded to routine antibiotics. Fortunately, the causative pathogen Orientia tsutsugamushi (Ot) was detected in the plasma samples of both patients using metagenomics next-generation sequencing (mNGS) and further confirmed by polymerase chain reaction. Subsequently, they both were treated with doxycycline and recovered quickly. Conclusion: The unbiased mNGS provided a clinically actionable diagnosis for an uncommon pathogen-associated infectious disease that had previously evaded conventional diagnostic approaches.