Breaking the Activity-Selectivity Trade-off for CH4-to-C2H6 Photoconversion.

Photocatalytic conversion of methane (CH4) to ethane (C2H6) has attracted extensive attention from academia and industry. Typically, the traditional oxidative coupling of CH4 (OCM) reaches a high C2H6 productivity, yet the inevitable overoxidation limits the target product selectivity. Although the traditional nonoxidative coupling of CH4 (NOCM) can improve the product selectivity, it still encounters unsatisfied activity, arising from being thermodynamically unfavorable. To break the activity-selectivity trade-off, we propose a conceptually new mechanism of H2O2-triggered CH4 coupling, where the H2O2-derived ·OH radicals are rapidly consumed for activating CH4 into ·CH3 radicals exothermically, which bypasses the endothermic steps of the direct CH4 activation by photoholes and the interaction between ·CH3 and ·OH radicals, affirmed by in situ characterization techniques, femtosecond transient absorption spectroscopy, and density-functional theory calculation. By this pathway, the designed Au-WO3 nanosheets achieve unprecedented C2H6 productivity of 76.3 mol molAu-1 h-1 with 95.2% selectivity, and TON of 1542.7 (TOF = 77.1 h-1) in a self-designed flow reactor, outperforming previously reported photocatalysts regardless of OCM and NOCM pathways. Also, under outdoor natural sunlight irradiation, the Au-WO3 nanosheets exhibit similar activity and selectivity toward C2H6 production, showing the possibility for practical applications. Interestingly, this strategy can be applied to other various photocatalysts (Au-WO3, Au-TiO2, Au-CeO2, Pd-WO3, and Ag-WO3), showing a certain universality. It is expected that the proposed mechanism adds another layer to our understanding of CH4-to-C2H6 conversion.

Unravelling structure evolution of dissolved organic matter during oxidation by persulfate: Insights from aromaticity and fluorescence analysis.

Persulfate advanced oxidation technology is widely utilized for remediating organic-contaminated groundwater. Post-remediation by persulfate oxidation, the aromaticity of dissolved organic matter (DOM) in groundwater is significantly reduced. Nevertheless, the evolution trends of aromaticity and related structural changes in DOM remained unclear. Here, we selected eight types of DOM to analyze the variation in aromaticity, molecular weight, and fluorescence characteristics during oxidation by persulfate using optical spectroscopy and parallel faction analysis combined with two-dimensional correlation spectroscopy analysis (2D PARAFAC COS). The results showed diverse trends in the changes of aromaticity and maximum fluorescence intensity (Fmax) among different types of DOM as the reaction time increases. Four types of DOM (humic acid 1S104H, fulvic acid, and natural organic matters) exhibited an initially noteworthy increase in aromaticity followed by a decrease, while others demonstrated a continuous decreasing trend (14.3%-69.4%). The overall decreasing magnitude of DOM aromaticity follows the order of natural organic matters ≈ commercial humic acid > fulvic acid > extracted humic acid. The Fmax of humic acid increased, exception of commercial humic acid. The Fmax of fulvic acid initially decreased and then increased, while that of natural organic matters exhibited a decreasing trend (86.4%). The fulvic acid-like substance is the main controlling factor for the aromaticity and molecular weight of DOM during persulfate oxidation process. The oxidation sequence of fluorophores in DOM is as follows: fulvic-like substance, microbial-derived humic-like substance, humic-like substance, and aquatic humic-like substance. The fulvic-like and microbial-derived humic-like substances at longer excitation wavelengths were more sensitive to the response of persulfate oxidation than that of shorter excitation wavelengths. This result reveals the structure evolution of DOM during persulfate oxidation process and provides further support for predicting its environmental behavior.

Light-Driven C-C Coupling for Targeted Synthesis of CH3 COOH with Nearly 100 % Selectivity from CO2.

Targeted synthesis of acetic acid (CH3 COOH) from CO2 photoreduction under mild conditions mainly limits by the kinetic challenge of the C-C coupling. Herein, we utilized doping engineering to build charge-asymmetrical metal pair sites for boosted C-C coupling, enhancing the activity and selectivity of CO2 photoreduction towards CH3 COOH. As a prototype, the Pd doped Co3 O4 atomic layers are synthesized, where the established charge-asymmetrical cobalt pair sites are verified by X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy spectra. Theoretical calculations not only reveal the charge-asymmetrical cobalt pair sites caused by Pd atom doping, but also manifest the promoted C-C coupling of double *COOH intermediates through shortening of the coupled C-C bond distance from 1.54 to 1.52 Å and lowering their formation energy barrier from 0.77 to 0.33 eV. Importantly, the decreased reaction energy barrier from the protonation of two*COOH into *CO intermediates for the Pd-Co3 O4 atomic layer slab is 0.49 eV, higher than that of the Co3 O4 atomic layer slab (0.41 eV). Therefore, the Pd-Co3 O4 atomic layers exhibit the CH3 COOH evolution rate of ca. 13.8 µmol g-1 h-1 with near 100% selectivity, both of which outperform all previously reported single photocatalysts for CO2 photoreduction towards CH3 COOH under similar conditions.

PDZK1 improves ventricular remodeling in hypertensive rats by regulating the stability of the Mas receptor.

Ventricular remodeling is one of the main causes of mortality from heart failure due to hypertension. Exploring its mechanism and finding therapeutic targets have become urgent scientific problems to be solved. A number of studies have shown that Mas, as an Ang-(1-7) specific receptor, was significantly reduced in myocardial tissue of rats undergoing hypertensive ventricular remodeling. It has been reported that Mas receptor levels are significantly downregulated in myocardium undergoing ventricular remodeling, but studies focused on intracellular and post-translational modifications of Mas are lacking. The results of this research are as follows: (1) PDZK1 interacts with the carboxyl terminus of Mas through its PDZ1 domain; (2) the expression of PDZK1 and Mas is decreased in rats undergoing hypertensive ventricular remodeling, and PDZK1 upregulation can ameliorate hypertensive myocardial fibrosis and myocardial hypertrophy; (3) PDZK1 enhances the stability of Mas protein through the proteasome pathway, and the proteasome inhibitor MG132 promotes hypertensive ventricular remodeling. PDZK1 improves ventricular remodeling in hypertensive rats by regulating Mas receptor stability. This study provides a scientific basis for the prevention and treatment of ventricular remodeling.

Insight into extracellular vesicles in vascular diseases: intercellular communication role and clinical application potential.

BACKGROUND: Cells have been increasingly known to release extracellular vesicles (EVs) to the extracellular environment under physiological and pathological conditions. A plethora of studies have revealed that EVs contain cell-derived biomolecules and are found in circulation, thereby implicating them in molecular trafficking between cells. Furthermore, EVs have an effect on physiological function and disease development and serve as disease biomarkers. MAIN BODY: Given the close association  between EV circulation and vascular disease, this review aims to provide a brief introduction to EVs, with a specific focus on the EV cargoes participating in pathological mechanisms, diagnosis, engineering, and clinical potential, to highlight the emerging evidence suggesting promising targets in vascular diseases. Despite the expansion of research in this field, some noticeable limitations remain for clinical translational research. CONCLUSION: This review makes a novel contribution to a summary of recent advances and a perspective on the future of EVs in vascular diseases. Video Abstract.

Changes in microRNA Expression Profiles in Diabetic Cardiomyopathy Rats Following H3 Relaxin Treatment.

ABSTRACT: MicroRNAs (miRNAs) are noncoding RNAs that play an important role in the mechanisms of diabetic cardiomyopathy (DCM); however, whether human recombinant relaxin-3 (H3 relaxin) inhibits myocardial injury in DCM rats and the underlying mechanisms involving miRNAs remain unknown. miRNA expression profiles were detected using miRNA microarray and bioinformatics analyses of myocardial tissues from control, DCM, and H3 relaxin-administered DCM groups, and the regulatory mechanisms of the miRNAs were investigated. A total of 5 miRNAs were downregulated in the myocardial tissues of DCM rats and upregulated in H3 relaxin-treated DCM rats, and 1 miRNA (miRNA let-7d-3p) was increased in the myocardial tissue of DCM rats and decreased in H3 relaxin-treated DCM rats as revealed by miRNA microarray and validated by real-time polymerase chain reaction. Important signaling pathways were found to be triggered by the differentially expressed miRNAs, including metabolism, cancer, Rap1, PI3K-Akt, and MAPK signaling pathways. The study revealed that H3 relaxin improved glucose uptake in DCM rats, potentially via the regulation of miRNA let-7d-3p.

Occurrence, distribution, and ecological risk of psychoactive substances in typical lakes and rivers in Qinghai-Tibet Plateau.

The occurrence, distribution, and ecological risks of psychoactive substances (PSs) in Qinghai-Tibet Plateau (QTP) was investigated in this study. The surface water samples were collected in July in 2020 from five major water bodies, and 9 PSs were determined by liquid chromatography-mass spectrometry. The mean concentrations of the total PSs were 2.19-96.86 ng/L in lakes and 4.56-34.47 ng/L in rivers. Amphetamine (AMP) was the predominant contaminant both in lakes and rivers with a mean concentration of 12.21 ± 22.76 ng/L and 9.83 ± 6.14 ng/L, respectively. The compositions of PSs in lakes and rivers were significantly different. AMP, methadone (MTD), 3,4-methylenedioxyamphetamine (MDA), and ketamine (KET) were the most detected contaminants in lakes, while in rivers AMP, MDA, heroin (HER), and methamphetamine (METH) were the most detected ones. Concentrations of AMP and MTD, the two predominant drugs, varied spatially, with the decreasing concentration of AMP in the order of Huangshui River > Yamzhog Yumco Lake > Qinghai Lake > Lhasa River > Namco Lake, and of MTD in the order of Qinghai Lake > Namco Lake > Huangshui River > Yamzhog Yumco Lake. The risk quotients (RQs) of PSs ranged from 4.44 × 10-6 to 4.32 × 10-2, indicating a low risk of PSs in the aquatic ecosystem in QTP. Compared with other research in the world, the contamination of psychoactive substances in the Qinghai-Tibet Plateau was at relatively low levels with low ecological risks.

A sensitive multimode dot-filtration strip for the detection of Salmonella typhimurium using MoS2@Fe3O4.

A sensitive, accurate, and rapid multimode dot-filtration immunoassay (MDFIA) was established for the detection of Salmonella typhimurium using the intrinsic color, catalytic property, and photothermal effect of magnetic molybdenum disulphide (MoS2@Fe3O4). The critical performance parameters of MDFIA were optimized in detail. The sensitivity of MDFIA can be improved by the catalytic color development and photothermal conversion of MoS2@Fe3O4 with a limit of detection (LOD) of 101 CFU·mL-1, which is an order of magnitude lower than direct visual detection (102 CFU·mL-1). Besides, the magnetic property of MoS2@Fe3O4 was used for the rapid enrichment and separation of the target allowing detection of trace concentrations of Salmonella typhimurium. The selectivity and applicability of the MDFIA were verified in spiked samples, indicating that the established assay may have bright application prospects for the detection and control of foodborne pathogens. A multimode dot-filtration immunoassay was constructed for Salmonella typhimurium rapid detection based on the peroxidase-like activity, magnetic property, and photothermal effect of MoS2@Fe3O4.

Selective CH4 Partial Photooxidation by Positively Charged Metal Clusters Anchored on Carbon Aerogel under Mild Conditions.

Selective partial photooxidation of CH4 into value-added chemicals under mild conditions still remains a huge bottleneck. Herein, we design positively charged metal clusters anchored on a three-dimensional porous carbon aerogel. With 0.75FeCA800-4 as an example, X-ray photoelectron spectra and Raman spectra disclose that the iron sites are positively charged. In situ electron paramagnetic resonance spectra show that the Feδ+ sites could donate electrons to activate CH4 into CH4- by virtue of the excited-state carbon atoms; meanwhile, they could convert H2O2 into •OH radicals under irradiation. In addition, in situ diffuse Fourier-transform infrared spectra suggest the CH3OOH obtained is derived from CH4 oxidation by the hydroxylation of *CH3 and *CH3O intermediates. Consequently, 0.75FeCA800-4 displays a CH3OOH selectivity of near 100% and a CH3OOH evolution rate of 13.2 mmol gFe-1 h-1, higher than those of most previously reported supported catalysts under similar conditions.

QuatJND: A Robust Quaternion JND Model for Color Image Watermarking.

Robust quantization watermarking with perceptual JND model has made a great success for image copyright protection. Generally, either restores each color channel separately or processes the vector representation from three color channels with the traditional monochromatic model. And it cannot make full use of the high correlation among RGB channels. In this paper, we proposed a robust quaternion JND Model for color image watermarking (QuatJND). In contrast to the existing perceptual JND models, the advantage of QuatJND is that it can integrate quaternion representation domain and colorfulness simultaneously, and QuatJND incorporates the pattern guided contrast masking effect in quaternion domain. On the other hand, in order to efficiently utilize the color information, we further develop a robust quantization watermarking framework using the color properties of the quaternion DCT coefficients in QuatJND. And the quantization steps of each quaternion DCT block in the scheme are optimal. Experimental results show that our method has a good performance in term of robustness with better visual quality.

Atom-Economical Synthesis of Dimethyl Carbonate from CO2 : Engineering Reactive Frustrated Lewis Pairs on Ceria with Vacancy Clusters.

The chemical conversion of CO2 to long-chain chemicals is considered as a highly attractive method to produce value-added organics, while the underlying reaction mechanism remains unclear. By constructing surface vacancy-cluster-mediated solid frustrated Lewis pairs (FLPs), the 100 % atom-economical, efficient chemical conversion of CO2 to dimethyl carbonate (DMC) was realized. By taking CeO2 as a model system, we illustrate that FLP sites can efficiently accelerate the coupling and conversion of key intermediates. As demonstrated, CeO2 with rich FLP sites shows improved reaction activity and achieves a high yield of DMC up to 15.3 mmol g-1 . In addition, by means of synchrotron radiation in situ diffuse reflectance infrared Fourier-transform spectroscopy, combined with density functional theory calculations, the reaction mechanism on the FLP site was investigated systematically and in-depth, providing pioneering insights into the underlying pathway for CO2 chemical conversion to long-chain chemicals.

Effect of the Substituent Position on the Phase Behavior and Photoresponsive Dynamic Behavior of Mixed Systems of a Gemini Surfactant and trans-Methoxy Sodium Cinnamates.

Mixed systems of the Gemini cationic surfactant trimethylene-1,3-bis (dodecyldimethylammonium bromide) (12-3-12·2Br-) and the photosensitive additives trans-methoxy sodium cinnamates with different substituent positions (trans-ortho-methoxy cinnamate, trans-OMCA; trans-meta-methoxy cinnamate, trans-MMCA; and trans-para-methoxy cinnamate, trans-PMCA) were selected for investigating the effects of the substituting position of methoxy on the system phase diagram and UV light-responsive behavior of the wormlike micelles. The differences in phase behaviors of the selected systems were analyzed by calculating the potential distribution, molecular volume, and free energy of solvation of cinnamates and the binding energies between photosensitive additives and the surfactant. The photoresponsive behaviors of wormlike micelle solutions formed in the selected systems were studied by the rheological method and UV-vis and H nuclear magnetic resonance (1H NMR) spectroscopy; the kinetics of photoisomerization of trans-OMCA, trans-MMCA, and trans-PMCA were studied by first-order derivative spectrophotometry. The results reveal that the methoxy substituent position has a great influence on the phase behavior and photosensitivity of the studied systems. In addition, the photoisomerization of the studied cinnamates follows the first-order opposite reaction laws; the different reaction rates play the decisive role in the photosensitivity of the wormlike micelles. This paper would afford a deeper understanding of the UV light-responsive mechanism at the molecular level and provide essential guidance in preparing smart materials with adjustable light sensitivity.

Inflammatory cytokines enhance procoagulant activity of platelets and endothelial cells through phosphatidylserine exposure in patients with essential hypertension.

The exact mechanism of the prothrombotic state of essential hypertension (EH) patients remains elusive. Our objective was to assess whether phosphatidylserine (PS) exposure on endothelial cells (ECs), platelets, and microparticles (MPs) can account for the hypercoagulability in EH patients. PS exposure on cells and MPs, mainly from platelets and ECs was analyzed with flow cytometry. Procoagulant activity (PCA) was evaluated by purified coagulation complex assays, clotting time, and fibrin turbidity. We found that EH patients exhibited elevated levels of PS+ platelets, serum-cultured ECs, MPs, endothelial-derived MPs and platelet-derived MPs compared to the controls (all P < 0.05). Moreover, platelets and MPs from the patients and their sera-cultured ECs showed markedly enhanced intrinsic/extrinsic FXa, thrombin, and fibrin generation, and greatly shortened coagulation time. This PCA could be blocked approximately 80%, by the addition of lactadherin. Furthermore, we detected elevated levels of IL-8, IL-6, and TNF-α in EH patients could activate platelets/ECs and induce elevated PS exposure on their membranes. Our results suggest that inflammatory cytokines could enhance procoagulant activity of platelets and endothelial cells via their PS exposure in EH patients. As such, a PS blockade may be a viable therapeutic strategy for treating such patients.

Exciton-Mediated Energy Transfer in Heterojunction Enables Infrared Light Photocatalysis.

Although a few semiconductors can directly absorb infrared light, their intrinsic properties like improper band-edge position and strong electron-hole interaction restrict further photocatalytic applications. Herein, we propose an exciton-mediated energy transfer strategy for realizing efficient infrared light response in heterostructures. Using black phosphorous/polymeric carbon nitride (BP/CN) heterojunction, CN could be indirectly excited by infrared light with the aid of nonradiatively exciton-based energy transfer from BP. At the same time, excitons are dissociated into free charge carriers at the interface of BP/CN heterojunction, followed by hole injection to BP and electron retainment in CN. As a result of these unique photoexcitation processes, BP/CN heterojunction exhibits promoted conversion rate and selectivity in amine-amine oxidative coupling reaction even under infrared light irradiation. This study opens a new way for the design of efficient infrared light activating photocatalysts.

Calhex231 ameliorates myocardial fibrosis post myocardial infarction in rats through the autophagy-NLRP3 inflammasome pathway in macrophages.

The calcium-sensing receptor (CaSR) is involved in the pathophysiology of many cardiovascular diseases, including myocardial infarction (MI) and hypertension. The role of Calhex231, a specific inhibitor of CaSR, in myocardial fibrosis following MI is still unclear. Using Wistar rats, we investigated whether Calhex231 ameliorates myocardial fibrosis through the autophagy-NLRP3 inflammasome pathway in macrophages post myocardial infarction (MI). The rats were randomly divided into sham, MI and MI + Calhex231 groups. Compared with the sham rats, the MI rats consistently developed severe cardiac function, myocardial fibrosis and infiltration of inflammatory cells including macrophages. Moreover, inflammatory pathway including activation of NLRP3 inflammasome, IL-1ß and autophagy was significantly up-regulated in myocardial tissue, infiltrated cardiac macrophages and peritoneal macrophages of the MI rats. These impacts were reversed by Calhex231. In vitro, studies revealed that calindol and rapamycin exacerbated MI-induced autophagy and NLRP3 inflammasome activation in peritoneal macrophages. Calhex231 and 3-Methyladenine (a specific inhibitor of autophagy) attenuated both autophagy and NLRP3 inflammasome activation; however, the caspase-1 inhibitor Z-YVAD-FMK did not. Our study indicated that Calhex231 improved cardiac function and ameliorated myocardial fibrosis post MI, likely via the inhibition of autophagy-mediated NLRP3 inflammasome activation; this provides a new therapeutic target for ventricular remodelling-related cardiovascular diseases.

An Excitonic Perspective on Low-Dimensional Semiconductors for Photocatalysis.

Low-dimensional semiconductors provide a marvelous platform for pursuing versatile photocatalytic solar energy conversion. Compared with the bulk counterparts, low-dimensional semiconductors possess notable Coulomb-interaction-mediated excitonic effects arising from the reduced dielectric screening. As a consequence, excitons or bound electron-hole pairs, together with charge carriers, serve as the primary photoinduced energetic species. In terms of photocatalysis, exciton-based energy transfer establishes distinctly different mechanisms for energy utilization beyond the traditional carrier-based charge transfer. Moreover, owing to the relationships between excitons and charge carriers, excitonic effects play a crucial role in determining quantum yields of both exciton- and carrier-triggered photocatalytic reactions. The above unique features enable optimized low-dimensional semiconductor-based photocatalysis to be achieved by non-trivial excitonic regulation. In this Perspective, we attempt to provide an overview of the impacts of excitonic effects on low-dimensional semiconductor-based photocatalysis. By figuring out the differences between excitons and charge carriers in degrees of freedom like spin and orbital, we emphasize the importance of unique excitonic properties in photocatalytic energy conversion. We discuss the interplay between the excitonic and charge-carrier aspects in low-dimensional semiconductors and highlight the necessity of evaluating excitonic effects when dealing with both exciton- and carrier-triggered photocatalytic reactions. We further review recent achievements in regulating the excitonic properties of low-dimensional semiconductor-based photocatalysts. We conclude the Perspective with an eye toward the future challenges in the field.

Molecular Dynamics Simulations and Density Functional Theory on Unraveling Photoresponsive Behavior of Wormlike Micelles Constructed by 12-2-12·2Br- and trans-ortho-Methoxy Cinnamate.

Photoresponsive systems with controllable self-assembly morphologies and adjustable rheological properties have attracted widespread interest by researchers in the past few years. Among them, the photoresponsive systems consisting of ortho-methoxycinnamic (OMCA) and Gemini surfactants are endowed with rich self-assemblies with different states and in different scales including spherical micelles, wormlike micelles, vesicles, aqueous two-phase system (ATPS), etc. All these self-assemblies display excellent photoresponsive behavior. However, the mechanism of these photoresponsive behaviors has not been unraveled systematically so far. In this study, molecular dynamics (MD) simulations, density functional theory (DFT) calculations, transmission electron microscopy, and rheology are employed to investigate the photoresponsive behaviors of wormlike micelles caused by photoisomerization of trans-OMCA in 12-2-12·2Br-/trans-OMCA solutions and to unravel the underlying mechanisms of these photoresponsive behaviors. The experimental results show that 12-2-12·2Br-/trans-OMCA micelles display photoresponsiveness after UV-light irradiation, with the transformation of micellar morphologies from wormlike micelle to spherical micelles. In MD simulations, certain micelle morphologies in experiments and the specific packing between 12-2-12·2Br-/OMCA were successfully captured. The larger three-dimensional structure and steric hindrance of cis-OMCA disturb the interior structure of micelles. The stronger hydrophilicity of cis-OMCA induces the escape of cis-OMCA from the interval of micelles to the solution. The energy results prove that trans-OMCA associates more strongly with 12-2-12·2Br- than cis-OMCA. These causes lead to the fission and repacking of wormlike micelles.

Effects of suppressing Smads expression on wound healing in Hyriopsis cumingii.

As a specific pearl mussel in China, Hyriopsis cumingii has enormous economic value. However, the organism damage caused by pearl insertion is immeasurable. TGF-ß/Smad signal transduction pathways are involved in all phases of wound healing. We have previously reported on two cytoplasmic signal transduction factors, Smad3 and Smad5 in mussel H. cumingii (named HcSmads), suggesting their involvements in wound healing. Here, Smad4 was cloned and described. The full length cDNA of HcSmad4 was 2543 bp encoded 515 amino acids. Deduced HcSmad4 protein possessed conserved MH1 and MH2 domains, nuclear location signals (NLS), nuclear exput signals (NES) and Smad activation domain (SAD). Transcripts of Smad3, 4 and 5 were constitutively expressed in all detected tissues, at highest levels in muscles. Furthermore, HcSmad4 mRNA levels were significantly increased at incision site post wounding, and expression of downstream target genes of Smad4, such as HcMMP1, HcMMP19, HcTIMP1 and HcTIMP2 were upregulated to a certain extent. Whatever knocked down HcSmad3/4 or treated by specific inhibitors of Smad 3 (SIS3), expression levels of these genes displayed a significantly downregulated tendency compared with the wound group. In addition, histological evaluation suggested that Smad3 knockdown or SIS3 treatment was accelerated wound healing, and then Smad4 knockdown delayed the process of wound healing in mussels. These data implicate that Smad3/4 play an important role in tissue repair in mollusks.

Ketones as Molecular Co-catalysts for Boosting Exciton-Based Photocatalytic Molecular Oxygen Activation.

Excitonic processes in semiconductors open up the possibility for pursuing photocatalytic organic synthesis. However, the insufficient spin relaxation and robust nonradiative decays in semiconductors place restrictions on both quantum yield and selectivity of these reactions. Herein, by taking polymeric carbon nitride (PCN)/acetone as a prototypical system, we propose that extrinsic aliphatic ketones can serve as molecular co-catalysts for promoting spin-flip transition and suppressing non-radiative energy losses. Spectroscopic investigations indicate that hot excitons in PCN can be transferred to ketones, while triplet excitons in ketones can be transferred to PCN. As such, the PCN/ketone systems exhibit considerable triplet-exciton accumulation and extended visible-light response, leading to excellent performance in exciton-based photocatalysis, such as singlet oxygen generation. This work provides a fundamental understanding of energy harvesting in semiconductor/molecule systems, and paves the way for optimizing exciton-based photocatalysis via molecular co-catalyst design.

A superoxide dismutase (MnSOD) with identification and functional characterization from the freshwater mussel Cristaria plicata.

Manganese superoxide dismutase (MnSOD) is a sort of important metalloenzyme that can catalyze ROS in the organisms. In this study, MnSOD cDNA of C. plicata, designated as CpMnSOD (accession no. MK465057), was cloned from hemocytes. The full-length cDNA of MnSOD was 1096 bp with a 672 bp open reading frame encoding 223 amino acids. The deduced amino acid sequence contained a mitochondrial-targeting sequence (MTS) of 18 amino acids in the N-terminus, and four conserved amino acids for manganese binding (H49, H97, D182, H186). CpMnSOD showed a high level (65-73%) of sequence similarity to MnSODs from other species. The results of Real-time quantitative PCR revealed that CpMnSOD mRNA constitutively expressed in tissues. The highest expression level was in hepatopancreas, followed by muscle, mantle and gill, and the lowest expression level was in hemocytes. After microcystin challenge, the expression levels of CpMnSOD mRNA were up-regulated in hemocytes and hepatopancreas. The cDNA of CpMnSOD was cloned into the plasmid pColdI-ZZ, and the recombinant protein was expressed in Escherichia coli BL21 (DE3). The enzyme stability assay showed that the purified CpMnSOD protein maintained more than 80% enzyme activity at temperature up to 70 °C, at pH 2.0-10.0, and resistant to 8 mol/L urea or 8% SDS.