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1.
Cell ; 187(7): 1719-1732.e14, 2024 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-38513663

RESUMEN

The glycine transporter 1 (GlyT1) plays a crucial role in the regulation of both inhibitory and excitatory neurotransmission by removing glycine from the synaptic cleft. Given its close association with glutamate/glycine co-activated NMDA receptors (NMDARs), GlyT1 has emerged as a central target for the treatment of schizophrenia, which is often linked to hypofunctional NMDARs. Here, we report the cryo-EM structures of GlyT1 bound with substrate glycine and drugs ALX-5407, SSR504734, and PF-03463275. These structures, captured at three fundamental states of the transport cycle-outward-facing, occluded, and inward-facing-enable us to illustrate a comprehensive blueprint of the conformational change associated with glycine reuptake. Additionally, we identified three specific pockets accommodating drugs, providing clear insights into the structural basis of their inhibitory mechanism and selectivity. Collectively, these structures offer significant insights into the transport mechanism and recognition of substrate and anti-schizophrenia drugs, thus providing a platform to design small molecules to treat schizophrenia.


Asunto(s)
Proteínas de Transporte de Glicina en la Membrana Plasmática , Humanos , Transporte Biológico , Glicina/metabolismo , Proteínas de Transporte de Glicina en la Membrana Plasmática/química , Proteínas de Transporte de Glicina en la Membrana Plasmática/metabolismo , Proteínas de Transporte de Glicina en la Membrana Plasmática/ultraestructura , Receptores de N-Metil-D-Aspartato/metabolismo , Esquizofrenia/metabolismo , Transmisión Sináptica , Imidazoles/química , Sarcosina/análogos & derivados , Piperidinas/química
2.
Mol Cell ; 83(7): 1109-1124.e4, 2023 04 06.
Artículo en Inglés | MEDLINE | ID: mdl-36921607

RESUMEN

The Polycomb-group chromatin modifiers play important roles to repress or switch off gene expression in plants and animals. How the active chromatin state is switched to a Polycomb-repressed state is unclear. In Arabidopsis, prolonged cold induces the switching of the highly active chromatin state at the potent floral repressor FLC to a Polycomb-repressed state, which is epigenetically maintained when temperature rises to confer "cold memory," enabling plants to flower in spring. We report that the cis-acting cold memory element (CME) region at FLC bears bivalent marks of active histone H3K4me3 and repressive H3K27me3 that are read and interpreted by an assembly of bivalent chromatin readers to drive cold-induced switching of the FLC chromatin state. In response to cold, the 47-bp CME and its associated bivalent chromatin feature drive the switching of active chromatin state at a recombinant gene to a Polycomb-repressed domain, conferring cold memory. We reveal a paradigm for environment-induced chromatin-state switching at bivalent loci in plants.


Asunto(s)
Proteínas de Arabidopsis , Arabidopsis , Cromatina/genética , Cromatina/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Proteínas de Dominio MADS/genética , Proteínas de Dominio MADS/metabolismo , Proteínas del Grupo Polycomb/genética , Proteínas del Grupo Polycomb/metabolismo , Arabidopsis/genética , Arabidopsis/metabolismo , Frío , Regulación de la Expresión Génica de las Plantas , Flores/genética , Flores/metabolismo
3.
J Am Chem Soc ; 146(20): 14278-14286, 2024 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-38727720

RESUMEN

The development of catalysts serves as the cornerstone of innovation in synthesis, as exemplified by the recent discovery of photoenzymes. However, the repertoire of naturally occurring enzymes repurposed by direct light excitation to catalyze new-to-nature photobiotransformations is currently limited to flavoproteins and keto-reductases. Herein, we shed light on imine reductases (IREDs) that catalyze the remote C(sp3)-C(sp3) bond formation, providing a previously elusive radical hydroalkylation of enamides for accessing chiral amines (45 examples with up to 99% enantiomeric excess). Beyond their natural function in catalyzing two-electron reductive amination reactions, upon direct visible-light excitation or in synergy with a synthetic photoredox catalyst, IREDs are repurposed to tune the non-natural photoinduced single-electron radical processes. By conducting wet mechanistic experiments and computational simulations, we unravel how engineered IREDs direct radical intermediates toward the productive and enantioselective pathway. This work represents a promising paradigm for harnessing nature's catalysts for new-to-nature asymmetric transformations that remain challenging through traditional chemocatalytic methods.

4.
BMC Neurol ; 24(1): 127, 2024 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-38627686

RESUMEN

BACKGROUND: Dementia prevalence is predicted to triple to 152 million globally by 2050. Alzheimer's disease (AD) constitutes 70% of cases. There is an urgent need to identify individuals with preclinical AD, a 10-20-year period of progressive brain pathology without noticeable cognitive symptoms, for targeted risk reduction. Current tests of AD pathology are either too invasive, specialised or expensive for population-level assessments. Cognitive tests are normal in preclinical AD. Emerging evidence demonstrates that movement analysis is sensitive to AD across the disease continuum, including preclinical AD. Our new smartphone test, TapTalk, combines analysis of hand and speech-like movements to detect AD risk. This study aims to [1] determine which combinations of hand-speech movement data most accurately predict preclinical AD [2], determine usability, reliability, and validity of TapTalk in cognitively asymptomatic older adults and [3], prospectively validate TapTalk in older adults who have cognitive symptoms against cognitive tests and clinical diagnoses of Mild Cognitive Impairment and AD dementia. METHODS: Aim 1 will be addressed in a cross-sectional study of at least 500 cognitively asymptomatic older adults who will complete computerised tests comprising measures of hand motor control (finger tapping) and oro-motor control (syllabic diadochokinesis). So far, 1382 adults, mean (SD) age 66.20 (7.65) years, range 50-92 (72.07% female) have been recruited. Motor measures will be compared to a blood-based AD biomarker, phosphorylated tau 181 to develop an algorithm that classifies preclinical AD risk. Aim 2 comprises three sub-studies in cognitively asymptomatic adults: (i) a cross-sectional study of 30-40 adults to determine the validity of data collection from different types of smartphones, (ii) a prospective cohort study of 50-100 adults ≥ 50 years old to determine usability and test-retest reliability, and (iii) a prospective cohort study of ~1,000 adults ≥ 50 years old to validate against cognitive measures. Aim 3 will be addressed in a cross-sectional study of ~200 participants with cognitive symptoms to validate TapTalk against Montreal Cognitive Assessment and interdisciplinary consensus diagnosis. DISCUSSION: This study will establish the precision of TapTalk to identify preclinical AD and estimate risk of cognitive decline. If accurate, this innovative smartphone app will enable low-cost, accessible screening of individuals for AD risk. This will have wide applications in public health initiatives and clinical trials. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT06114914, 29 October 2023. Retrospectively registered.


Asunto(s)
Enfermedad de Alzheimer , Disfunción Cognitiva , Humanos , Femenino , Anciano , Persona de Mediana Edad , Anciano de 80 o más Años , Masculino , Enfermedad de Alzheimer/diagnóstico , Enfermedad de Alzheimer/epidemiología , Enfermedad de Alzheimer/psicología , Teléfono Inteligente , Estudios Prospectivos , Estudios Transversales , Reproducibilidad de los Resultados , Disfunción Cognitiva/diagnóstico , Biomarcadores , Péptidos beta-Amiloides
5.
Environ Res ; 243: 117738, 2024 Feb 15.
Artículo en Inglés | MEDLINE | ID: mdl-37993048

RESUMEN

Algae have great application prospects in excess sludge reclamation and recovery of high-value biomass. Chlorococcum humicola was cultivated in this research, using sludge extract (mixed with SE medium) with additions of 10%, 20%, and 30% CO2 (v/v). Results showed that under 20% CO2, the dry weight and polysaccharide yield reached 1.389 ± 0.070 g/L and 313.49 ± 10.77 mg/L, respectively. 10% and 20% CO2 promoted the production of cellular antioxidant molecules to resist the toxic stress and the toxicity of 20% CO2 group decreased from 62.16 ± 3.11% to 33.02 ± 3.76%. 10% and 20% CO2 accelerated the electron transfer, enhanced carbon assimilation, and promoted the photosynthetic efficiency, while 30% CO2 led to photosystem damage and disorder of antioxidant system. Proteomic analysis showed that 20% CO2 mainly affected energy metabolism and the oxidative stress level on the early stage (10 d), while affected photosynthesis and organic substance metabolism on the stable stage (30 d). The up-regulation of PSII photosynthetic protein subunit 8 (PsbA, PsbO), A0A383W1S5 and A0A383VRI4 promoted the efficiency of PSII and chlorophyll synthesis, and the up-regulation of A0A383WH74 and A0A2Z4THB7 led to the accumulation of polysaccharides. The up-regulation of A0A383VDH1, A0A383VX37 and A0A383VA86 promoted respiration. Collectively, this work discloses the regulatory mechanism of high-concentration CO2 on Chlorococcum humicola to overcome toxicity and accumulate polysaccharides.


Asunto(s)
Dióxido de Carbono , Clorofila , Clorofila/metabolismo , Dióxido de Carbono/toxicidad , Antioxidantes , Proteómica , Aguas del Alcantarillado
6.
Artículo en Inglés | MEDLINE | ID: mdl-38606832

RESUMEN

Osteoarthritis occurs in any joints, and identification in its earlier stages helps to treat the disease and increase the recovery rate. The radiography method and imaging techniques are traditionally used to identify osteoarthritis. But these methods are expensive, and with the complicated steps. Researchers are working toward developing a highly sensitive biosensor in identifying the osteoarthritis biomarker. This research was focused on developing a C-terminal telopeptide of type II collagen (CTX-II) colorimetric sensor with gold nanoparticle (AuNP) for diagnosing osteoarthritis. Anti-CTX-II was conjugated with AuNP and then added with CTX-II and sodium chloride for the color change. In the presence of CTX-II, antibody releases from AuNP then binds with CTX-II, and the color of AuNP changed to purple. Without the CTX-II, AuNP remains its red color (dispersed). This easier colorimetric assay detected the CTX-II as low as 2 ng/mL on linear regression [y = 0.0131x - 0.0051; R2 = 0.9205]. Furthermore, control performances with the relevant proteins osteopontin, IL-6, and nonimmune antibody failed to change the color confirming the specific identification of CTX-II.

7.
J Chem Phys ; 160(22)2024 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-38874102

RESUMEN

Experimental and numerical studies were performed on the vibrational energy relaxation in shock-heated CO/N2/Ar mixtures. A laser absorption technique was applied to the time-dependent rovibrational temperature time-history measurements. The vibrational relaxation data of reflected-shock-heated CO were summarized at 1720-3230 K. In shock-tube experiments, the rotational temperature of CO quickly reached equilibrium, whereas a relaxation process was found in the time-dependent vibrational temperature. For the mixture with 1.0% CO and 10.0% N2, the vibrational excitation caused a decrease in the macroscopic thermodynamic temperature of the test gas. In the simulations, the state-to-state (StS) approach was employed, where the vibrational energy levels of CO and N2 are treated as pseudo-species. The vibrational state-specific inelastic rate coefficients of N2-Ar collisions were calculated using the mixed quantum-classical method based on a newly developed three-dimensional potential energy surface. The StS predictions agreed well with the measurements, whereas deviations were found between the Schwartz-Slawsky-Herzfeld formula predictions and the measurements. The Millikan-White vibrational relaxation data of the N2-Ar system were found to have the most significant impact on the model predictions via sensitivity analysis. The vibrational relaxation data of the N2-Ar system were then modified according to the experimental data and StS results, providing an indirect way to optimize the vibrational relaxation data of a specific system. Moreover, the vibrational distribution functions of CO and N2 and the effects of the vibration-vibration-translation energy transfer path on the thermal nonequilibrium behaviors were highlighted.

8.
BMC Musculoskelet Disord ; 25(1): 538, 2024 Jul 12.
Artículo en Inglés | MEDLINE | ID: mdl-38997705

RESUMEN

BACKGROUND: How to quickly read and interpret intraoperative ultrasound (IOUS) images of patients with degenerative cervical myelopathy (DCM) to obtain meaningful information? Few studies have systematically explored this topic. PURPOSE: To systematically and comprehensively explore the IOUS characteristics of patients with DCM. MATERIALS AND METHODS: This single-center study retrospectively included patients with DCM who underwent French-door laminoplasty (FDL) with IOUS guidance from October 2019 to March 2022. One-way ANOVA and Pearson's /Spearman's correlation analysis were used to analyze the correlations between the cross-sectional area of the spinal cord (SC) and individual characteristics; the relationships between the morphology, echogenicity, pulsation, decompression statuses, compression types of SC, location of the spinal cord central echo complex (SCCEC) and the disease severity (the preoperative Japanese Orthopedic Association score, preJOA score); the difference of the spinal cord pulsation amplitude(SCPA) and the SCCEC forward movement rate (FMR) between the compressed areas(CAs) and the non-compressed areas (NCAs). RESULTS: A total of 38 patients were successfully enrolled (30 males and 8 females), and the mean age was 57.05 ± 10.29 (27-75) years. The cross-sectional area of the SC was negatively correlated with age (r = - 0.441, p = 0.006). The preJOA score was significantly lower in the heterogeneous group than in the homogeneous group (P < 0.05, p = 0.005). The hyperechoic area (HEA) was negatively while the SCCEC FMR was positively correlated with the preJOA score (r = - 0.334, p = 0.020; r = 0.286, p = 0.041). The SCCEC FMR and SCPA in CAs were significantly greater than those in NCAs (p < 0.05, p = 0.007; P < 0.001, P = 0.000). CONCLUSION: The cross-sectional area of the SC decreases with age in adults. More changes in intramedullary echogenicity and less moving forward of the SCCEC often indicate poor SC status, and the SCCEC FMR and SCPA are more pronounced in CAs.


Asunto(s)
Vértebras Cervicales , Laminoplastia , Humanos , Masculino , Femenino , Persona de Mediana Edad , Anciano , Estudios Retrospectivos , Vértebras Cervicales/cirugía , Vértebras Cervicales/diagnóstico por imagen , Adulto , Laminoplastia/métodos , Enfermedades de la Médula Espinal/cirugía , Enfermedades de la Médula Espinal/diagnóstico por imagen , Ultrasonografía , Compresión de la Médula Espinal/cirugía , Compresión de la Médula Espinal/diagnóstico por imagen
9.
Int J Phytoremediation ; 26(7): 1117-1132, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38099523

RESUMEN

Little information is available on the influence of the compound use of intercropping (IN) and arbuscular mycorrhizal fungus (AMF) on Cd accumulation and the expression of Cd transporter genes in two intercropped plants. A pot experiment was conducted to study the influences of IN and AMF-Glomus versiforme on growth and Cd uptake of two intercropped plants-maize and Cd hyperaccumulator Sphagneticola calendulacea, and the expression of Cd transporter genes in maize in Cd-polluted soils. IN, AMF and combined treatments of IN and AMF (IN + AMF) obviously improved biomass, photosynthesis and total antioxidant capacities of two plants. Moreover, single and compound treatments of IN and AMF evidently reduced Cd contents in maize, and the greatest decreases appeared in the compound treatment. However, Cd contents of S. calendulacea in IN, AMF and IN + AMF groups were notably improved. Furthermore, the single and compound treatments of IN and AMF significantly downregulated the expression levels of Nramp1, HMA1, ABCC1 and ABCC10 in roots and leaves, and the largest decreases were observed in the combined treatment. Our work first revealed that the combined use of IN and AMF appeared to have a synergistic effect on decreasing Cd content by downregulating the expression of Cd transporter genes in maize.


Asunto(s)
Biodegradación Ambiental , Cadmio , Micorrizas , Contaminantes del Suelo , Zea mays , Zea mays/metabolismo , Zea mays/microbiología , Micorrizas/fisiología , Cadmio/metabolismo , Contaminantes del Suelo/metabolismo , Glomeromycota/fisiología , Asteraceae/metabolismo
10.
Angew Chem Int Ed Engl ; 63(24): e202317177, 2024 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-38606608

RESUMEN

Co-intercalation reactions make graphite a feasible anode in Ca ion batteries, yet the correlation between Ca ion intercalation behaviors and electrolyte structure remains unclear. This study, for the first time, elucidates the pivotal role of anions in modulating the Ca ion solvation structures and their subsequent intercalation into graphite. Specifically, the electrostatic interactions between Ca ion and anions govern the configurations of solvated-Ca-ion in dimethylacetamide-based electrolytes and graphite intercalation compounds. Among the anions considered (BH4 -, ClO4 -, TFSI- and [B(hfip)4]-), the coordination of four solvent molecules per Ca ion (CN=4) leads to the highest reversible capacities and the fastest reaction kinetics in graphite. Our study illuminates the origins of the distinct Ca ion intercalation behaviors across various anion-modulated electrolytes, employing a blend of experimental and theoretical approaches. Importantly, the practical viability of graphite anodes in Ca-ion full cells is confirmed, showing significant promise for advanced energy storage systems.

11.
Small ; 19(3): e2205088, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36424142

RESUMEN

Surface defects-mediated nonradiative recombination plays a critical role in the performance and stability of perovskite solar cells (PSCs) and surface post-treatment is widely used for efficient PSCs. However, the commonly used surface passivation strategies are one-off and the passivation defect ability is limited, which can only solve part of the defects in the topmost surface area. Here, a secondary anti-solvent strategy is proposed to further reduce surface defects based on conventional surface passivation for the first time. Based on this, the crystallization quality of 2D Dion-Jacobson perovskite is enhanced and the surface defects density is further reduced by nearly two orders. In addition, a gradient structure of perovskite with n = 2 phases located at the top of the film and 3D-like phases located at the bottom of the film can also be obtained. The modulated perovskite film boosts the efficiency of 2D perovskites (n = 5) up to 19.55%. This strategy is also very useful in other anti-solvent processed perovskite dipping systems, which paves a promising avenue for minimizing surface defects toward highly efficient perovskite devices.

12.
Small ; 19(17): e2207313, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36709424

RESUMEN

Membrane-based carbon dioxide (CO2 ) capture and separation technologies have aroused great interest in industry and academia due to their great potential to combat current global warming, reduce energy consumption in chemical separation of raw materials, and achieve carbon neutrality. The emerging covalent organic frameworks (COFs) composed of organic linkers via reversible covalent bonds are a class of porous crystalline polymers with regular and extended structures. The inherent structure and customizable organic linkers give COFs high and permanent porosity, short transport channel, tunable functionality, and excellent stability, thereby enabling them rising-star alternatives for developing advanced CO2 separation membranes. Therefore, the promising research areas ranging from development of COF membranes to their separation applications have emerged. Herein, this review first introduces the main advantages of COFs as the state-of-the-art membranes in CO2 separation, including tunable pore size, modifiable surfaces property, adjustable surface charge, excellent stability. Then, the preparation approaches of COF-based membranes are systematically summarized, including in situ growth, layer-by-layer stacking, blending, and interface engineering. Subsequently, the key advances of COF-based membranes in separating various CO2 mixed gases, such as CO2 /CH4 , CO2 /H2 , CO2 /N2 , and CO2 /He, are comprehensively discussed. Finally, the current issues and further research expectations in this field are proposed.

13.
Opt Express ; 31(13): 22144-22156, 2023 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-37381295

RESUMEN

Aiming at the problems of narrow working bandwidth, low efficiency, and complex structure of existing terahertz chiral absorption, we propose a chiral metamirror composed of C-shaped metal split ring and L-shaped vanadium dioxide (VO2). This chiral metamirror is composed of three layers of structure, a gold substrate at the bottom, the first polyethylene cyclic olefin copolymer (Topas) dielectric layer and VO2-metal hybrid structure as the top. Our theoretical results led us to show that this chiral metamirror has a circular dichroism (CD) value greater than 0.9 at 5.70 to 8.55 THz and has a maximum value of 0.942 at f = 7.18 THz. In addition, by adjusting the conductivity of VO2, the CD value can be continuously adjustable from 0 to 0.942, which means that the proposed chiral metamirror supports the free switching of the CD response between the on and off states, and the CD modulation depth exceeds 0.99 in the range of 3 to 10 THz. Moreover, we discuss the influence of structural parameters and the change of incident angle on the performance of the metamirror. Finally, we believe that the proposed chiral metamirror has important reference value in the terahertz range for constructing chiral light detectors, CD metamirrors, switchable chiral absorbers and spin-related systems. This work will provide a new idea for improving the terahertz chiral metamirror operating bandwidth and promote the development of terahertz broadband tunable chiral optical devices.

14.
Opt Lett ; 48(7): 1702-1705, 2023 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-37221745

RESUMEN

Optical resonant cavities with high quality factor (Q-factor) are widely used in science and technology for their capabilities of strong confinement of light and enhanced light-matter interaction. The 2D photonic crystal structure with bound states in the continuum (BICs) is a novel concept for resonators with ultra-compact device size, which can be used to generate surface emitting vortex beams based on symmetry-protected BICs at the Γ point. Here, to the best of our knowledge, we demonstrate the first photonic crystal surface emitter with a vortex beam by using BICs monolithically grown on CMOS-compatible silicon substrate. The fabricated quantum-dot BICs-based surface emitter operates at 1.3 µm under room temperature (RT) with a low continuous wave (CW) optically pumped condition. We also reveal the BIC's amplified spontaneous emission with the property of a polarization vortex beam, which is promising to provide a novel degree of freedom in classical and quantum realms.

15.
Opt Lett ; 48(19): 5153-5156, 2023 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-37773408

RESUMEN

The deep application of chiral metasurfaces requires higher flexibility. Herein, we propose a multidimensional tunable chiral graphene metasurface, which uses coherent control to obtain more than 0.8 circular conversion dichroism (CCD) at 2.4 THz as a transmission structure. Its operating frequency can be changed in the 1.3-2.4 THz range, while the amplitude has almost perfect modulation depth in the range of 0-0.8. The mechanism of differential absorption was analyzed through numerical simulation. The device designed is easy to obtain reverse CCD, which is used for unit layout and proves its advantages in near-field imaging. Our work has broadened the path for the development of chiral metasurfaces towards higher degrees of freedom.

16.
Nanotechnology ; 34(31)2023 May 18.
Artículo en Inglés | MEDLINE | ID: mdl-37015216

RESUMEN

An efficient broadband responsive two-dimensional (2D) heterometallic Zn-/Co-porphyrin conjugated polymer (ZnCoP-F CP) with its Co-porphyrin bridging unit bearing two perfluorophenyls is coupled with 2.0 wt% Pt-loaded graphite carbon nitride (PCN) to fabricate a novel 2D/2D nanocomposite (ZnCoP-F/PCN). The resultant ZnCoP-F/PCN composite with an optimal mass ratio exhibits broadband (UV-vis-NIR) responsive H2evolution reaction (HER) activity up to 432µmol h-1, 5.2 and 2.8 times higher than that of the ZnCoP-F CP (83µmol h-1) and PCN (151µmol h-1) alone, respectively. Furthermore, the ZnCoP-F/PCN displays excellent apparent quantum yields (AQY) of 18.2%, 18.3%, 17.6%, 16.5%, 13.9%, 8.7%, 5.1%, 4.3%, 1.9%, 0.95% and 0.62% at 350, 380, 420, 450, 500, 550, 600, 700, 785, 850 and 950 nm, which are also higher than that of ZnCoP-F CP illuminated at the respective monochromatic light. The enhanced broadband responsive HER performance of ZnCoP-F/PCN can be attributed to the easily assembled ZnCoP-F CP and PCN nanosheets through strongπ-πstacking interaction, which can facilitate the fast charge transfer from ZnCoP-F CP to PCN for HER. This work opens a new pathway to fabricate porphyrin polymer-based nanocomposite for more efficiently converting solar radiation and water into H2.

17.
Environ Res ; 238(Pt 2): 117252, 2023 12 01.
Artículo en Inglés | MEDLINE | ID: mdl-37783322

RESUMEN

It has been an urgent requirement for materials with remarkable performance in the photocatalytic degradation of organic contaminants by photocatalytic technology. Limited surface area and speedy recombination rate of photogenerated charge carriers seriously restrain the application of g-C3N4. Morphology control is a powerful approach to enhance the photocatalytic efficiency of g-C3N4. Herein, we reported a method to attain graphitic carbon nitride with rectangular hollow tubular morphology and asperous surface (TUM-CN-2) which is prepared from urea-melamine hydrothermal products and trithiocyanuric acid by self-assembling without using organic solvents or template agents. The specific surface area, photocatalytic activity, and photo-generated carriers migration and separation rate of the obtained photocatalyst TUM-CN-2 are vastly improved. Contrasted with pure g-C3N4, the degradation rate of tetracycline hydrochloride (TCH) and Rhodamine B (RhB) was enhanced about 3.04 and 13.96 times in visible light irradiation, respectively. Moreover, the interference parameters, active free radicals, potential degradation mechanism, and degradation paths of TCH were researched systematically. This work provides a green way to acquire the modified g-C3N4 with splendid catalytic activity through the self-assembly method.


Asunto(s)
Luz , Tetraciclina , Nitrilos , Radicales Libres
18.
Biotechnol Appl Biochem ; 70(2): 798-810, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36070874

RESUMEN

Sulforaphane (SFN), a defense secondary metabolite, can be used to predict the health status of plants and also has pharmacological effects, including anticancer, antioxidant, and anti-inflammatory properties. The detection of SFN is therefore of great significance for the prevention and treatment of diseases. In this study, a "turn off" whole-cell biosensor that can rapidly and robustly respond to the presence of SFN was constructed based on the orthogonal genetic components (hrpR, hrpS, and PhrpL ) of Pseudomonas syringae (PS). The final optimized biosensor, p114(30R-30S), was able to inhibit 91.7% of the fluorescence intensity in the presence of 100-µM SFN. Subsequently, a HrpRS-regulated OFF-ON genetic switch was designed by reconstituting a reverse σ70 promoter on the σ54 -PhrpL promoter sequence; this was coupled with dual-color reporter genes to construct a "turn off-on" whole-cell SFN biosensor. The PhrpLB variant increased the expression of green fluorescence a factor of 11.9 and reduced the expression of red fluorescence by 85.8% compared with the system in the absence of SFN. Thus, a robust switching of signal output from "turn off" to "turn on" was realized. In addition, the biosensor showed good linearity in the SFN concentration ranges of 0.1-10 µM (R2  = 0.99429) and 10-100 µM (R2  = 0.99465) and a detection limit of ~0.1 µM.


Asunto(s)
Proteínas Bacterianas , Factores de Transcripción , Factores de Transcripción/metabolismo , Proteínas Bacterianas/genética , Isotiocianatos/farmacología , Sulfóxidos
19.
Appl Opt ; 62(23): 6205-6211, 2023 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-37707089

RESUMEN

In this paper, a nested micro-ring refractive index sensor based on a subwavelength grating waveguide and the Vernier effect is proposed. In this scheme, the nested micro-ring structure is combined with a subwavelength grating structure to enhance the contact area between the optical field and the analyte, and the wavelength offset is doubled through the Vernier effect. The proposed sensor can effectively increase sensing sensitivity, taking into account the improvement of the free spectral range. This structure enables the device to reach a sensitivity of 8030 nm/RIU near 1550 nm wavelength in a deionized water environment, with a detection limit of 5.659×10-5 RIU and free spectral range of 41.956 nm. The device suggested in this study has a greater reduced footprint than the conventional micro-ring resonant sensor, measuring just 35µm×25µm. Due to its high integration, high sensitivity, and large free spectral range compared to conventional micro-ring resonant sensors, such structures are of great value in biosensing and environmental monitoring.

20.
Appl Opt ; 62(28): 7346-7353, 2023 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-37855501

RESUMEN

Electro-optic modulators are essential devices on silicon photonic chips in modern optical communication networks. This paper presents a compact, low-loss electro-optic modulator. The modulation efficiency is greatly improved by embedding the lower half of the slot waveguide into the buried oxide layer and inserting graphene at the junction. The interaction of graphene with an optical field in a waveguide is studied using the finite element method. The functions of phase modulation and absorption modulation are realized by changing the gate voltage to change the chemical potential of graphene. The semi-embedded slot waveguide optical modulator has a length of 50 µm. After simulation verification, it can be used as an electro-absorption modulator and can achieve a modulation depth of 26.38 dB and an insertion loss of 0.60 dB. When used as an electro-refractive modulator, it can be realized with a linear change of phase from zero to π; the total insertion loss is only 0.59 dB. The modulator has a modulation bandwidth of 79.6 GHz, and the energy consumption as electro-absorption and electro-refraction modulation are 0.51 and 1.92 pj/bit, respectively. Compared with common electro-optic modulators, the electro-optic modulator designed in this paper has a higher modulation effect and also takes into account the advantages of low insertion loss and low energy consumption. This research is helpful for the design of higher-performance optical communication network devices.

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