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1.
Food Chem ; 369: 130920, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34461518

RESUMO

Chinese traditional fermented baijiu is a famous alcoholic beverage with unique flavor. Despite its consumption for millennia, the flavor mystery behind baijiu is still unclear. Studies indicate that esters are the most important flavor substances, and bring health benefits. However, the aroma contribution and formation mechanism of esters still need to be clarified to reveal the flavor profile of baijiu. This review systematically summarizes all the 510 esters and finds 9 ethyl esters contribute greatly to the flavor of baijiu. The 508 different microbial species that have been identified affect the synthesis of esters through fatty acid and amino acid metabolism. The determination of minimum functional microbial groups and the analysis of their metabolic characteristics are crucial to reveal the mechanism of formation of baijiu flavor, and ensure the reproducible formation of flavor substances.


Assuntos
Ésteres , Aromatizantes , China , Fermentação , Aromatizantes/análise , Odorantes/análise , Paladar
2.
J Mater Chem B ; 2021 Dec 02.
Artigo em Inglês | MEDLINE | ID: mdl-34854861

RESUMO

Fluorescence imaging in the second near-infrared window (NIR-II) has been an emerging technique in diverse in vivo applications with high sensitivity/resolution and deep tissue penetration. To date, the design principle of the reported NIR-II organic fluorophores has heavily relied on benzo[1,2-c:4,5-c']bis([1,2,5]thiadiazole) (BBTD) as a strong electron acceptor. Here, we report the rational design and synthesis of a NIR-II fluorescent molecule with the rarely used [1,2,5]thiadiazolo[3,4-f]benzotriazole (TBZ) core to replace BBTD as the electron acceptor. Thanks to the weaker electron deficiency of the TBZ core than BBTD, the newly yielded NIR-II molecule (BTB) based nanoparticles have a higher mass extinction coefficient and quantum yield in water. In contrast, the nanoparticle suspension of its counterpart with BBTD as the core is nearly nonemissive. The NIR-II BTB nanoparticles allow video-rate fluorescence imaging for vasculature imaging in ears, hindlimbs, and the brain of the mouse. Additionally, its large absorptivity in the NIR-I region also promotes bioimaging using photoacoustic microscopy (PAM) and tomography (PAT). Upon surface conjugation with the Arg-Gly-Asp (RGD) peptide, the functionalized nanoparticles ensured targeted detection of integrin-overexpressed tumors through both imaging modalities in two- and three-dimensional views. Thus, our approach to engineering acceptors of organic fluorophores offers a promising molecular design strategy to afford new NIR-II fluorophores for versatile biomedical imaging applications.

3.
J Phys Chem Lett ; 12(45): 11042-11049, 2021 Nov 18.
Artigo em Inglês | MEDLINE | ID: mdl-34747623

RESUMO

A good purification strategy for obtaining high-quality and low-cost perovskite QDs ink requires a complete removal of the impurities but with a minimal phase transition of QDs from the perovskite phases to the nonperovskite δ-phase. This pioneering work reports the electrochemical quantification on the phase transition level of CsPbI3 QDs in purification. Cyclic voltammetry of the purified QDs evidenced the formation of a new product in the purification process, which was demonstrated to be the undesired nonperovskite δ-phase by independent structural analysis. The developed electrochemical methodology further enabled the quantification of the extent of the phase transition of the QDs purified using different strategies by simply analyzing the charge associated with the relevant peaks and allowing optimization of the purification. The latter is of vital importance for commercialization and is an essential step for boosting their device performance.

4.
Int J Biol Macromol ; 192: 644-653, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34655580

RESUMO

Low-sugar and high-protein adhesives have broad market application prospects, while natural plant proteins have confronted technical bottlenecks due to their poor adhesion. In this study, the effects of ethanol with different concentrations (0-80%) on the adhesion properties of walnut protein isolate-xanthan gum (WNPI-XG) composite adhesives were investigated. Results showed the bonding strength of WNPI-XG treated with 40% ethanol reached 12.55 MPa, the denaturation temperature and the surface hydrophobicity increased to 87.91 and 185.07 respectively, displaying the best rheological and texture properties. It also indicated appropriate concentration of ethanol (40%) didn't change the molecular weight of WNPI-XG, but greatly strengthened the fluorescence intensity, leading changes in contents of reactive sulfhydryl groups, electrostatic forces, hydrophobic interactions, hydrogen bonds and disulfide bonds. Furthermore, the treatment also facilitated a conformation conversion of the secondary structures from ß-sheet to α-helix, promoting the full unfolding of protein molecules. The microstructure analysis showed after 40% ethanol treatment, the WNPI structure was uniform, the surface of WNPI-XG adhesive was flat and smooth, combined more closely with water molecules. By analyzing the influence of ethanol treatment on adhesion of WNPI-XG, the research laid a theoretical foundation for protein modification, providing good technical references for its development and utilization.

5.
J Orthop Surg Res ; 16(1): 649, 2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34717681

RESUMO

OBJECTIVE: This study aimed to describe the characteristics of plasma D-dimer level with increasing age and establish a new age-adjusted D-dimer cutoff value for excluding preoperative lower limb deep vein thrombosis (DVT) in elderly patients with hip fractures. METHODS: This was a retrospective study of elderly patients who presented with acute hip fracture in our institution between June 2016 and June 2019. All patients underwent D-dimer test and duplex ultrasound. Patients were divided into six 5-year-apart age groups. The optimal cutoff value for each group was calculated by using receiver operating characteristic (ROC) curves, whereby the new age-adjusted D-dimer cutoff value was determined. The sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) were calculated and compared when different D-dimer cutoff values were applied, i.e., conventional 0.5 mg/L, previously well-established age-adjusted cutoff value (age × 0.01 mg/L) and the new age-adjusted D-dimer cutoff value herein. RESULTS: There were 2759 patients included, 887 males and 1872 females, with an average age of 78 years. In total, 280 patients were diagnosed with preoperative DVT. The optimal cutoff values for the six age groups were 0.715 mg/L, 1.17 mg/L, 1.62 mg/L, 1.665 mg/L, 1.69 mg/L and 1.985 mg/L, respectively, and the calculated age-adjusted coefficient was 0.02 mg/L. With this new coefficient applied, the specificity was 61%, clearly higher than those for conventional threshold (0.5 mg/L, 37%) or previously established age-adjusted D-dimer threshold (age × 0.01 mg/L, 22%). In contrast, the sensitivity was lower than that (59% vs 85% or 77%) when D-dimer threshold of 0.5 mg/L or age-adjusted cutoff value (age × 0.01 mg/L) was used. The other indexes as PPV (15%, 11% and 12%) and NPV (93%, 93% and 94%) were comparable when three different D-dimer thresholds were applied. CONCLUSIONS: We developed a new age-adjusted D-dimer cutoff value (age × 0.02 mg/L) for a specified high-risk population of patients aged 65 years or older with hip fractures, and demonstrated the improved utility of the D-dimer test for exclusion of DVT. This formula can be considered for use in elderly hip fracture patients who meet the applicable standards as preoperative DVT screening, after its validity is confirmed by more well-evidenced studies.

6.
Ultrason Sonochem ; 78: 105717, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34509956

RESUMO

Pumpkin seed oil (PSO), which is a valuable compound with high nutritional value used for the prevention of various chronic diseases, is prone to oxidation. In this work, small and uniform (su) ovalbumin (OVA) and pectin (PEC) were used to stabilize PSO in the form of an emulsion. The results showed that suOVA-PEC-PSO emulsion with a droplet size of 9.82 ± 0.05 µm was successfully self-assembled from PSO, PEC, and suOVA solution (with a droplet size of 230.13 ± 14.10 nm) treated with 300 W ultrasound, owing to the formation of a more stable interfacial film on the surface of droplets. The interfacial, rheological, emulsifying, and antioxidant properties of the suOVA-PES-PSO emulsions were excellent, owing to the synergistic effects between PEC and suOVA solution. Moreover, the physical stability of the suOVA-PEC-PSO emulsions to salt stress, a freeze-thaw cycle, and heat treatment was also increased and the oxidation of linolenic acid was notably delayed. These results have extended the food-related applications of OVA and PSO, and provide a promising foundation for further exploration of the self-assembly of composite emulsions by small and uniform proteins.

7.
Front Bioeng Biotechnol ; 9: 755003, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34568305

RESUMO

A novel treatment involving enzymatic hydrolysis using an acidic xylanase coupled with ultrasound was performed to improve the xylo-oligosaccharides (XOS) yield from corncob bran. The acidic xylanase (XynB) was purified to a most suitable pH, temperature, and operational parameters for ultrasound-assisted hydrolysis were determined. A preliminary mechanistic investigation was performed through circular dichroism (CD) spectroscopy, scanning electron microscope (SEM) and a laser particle size analyzer, and the effects of ultrasound on enzyme (XynB) and substrate (corncob bran) were assessed. The results show that the maximum XOS yield was 20.71% when the reaction pH and temperature were 4.3 and 50°C, the ultrasonic parameters were 50 kHz and 0.40 W/cm2, which was 2.55 fold higher than that obtained using a non-ultrasound-assisted enzymatic preparation. Mechanism studies indicated that ultrasonic pretreatment could reduce the ß-fold content and increase the random coil content. Changes in structure and size of substrate were observed. The specific surface area of the XAC molecules is easy to carry out enzymatic reaction, which is beneficial to the production of XOS.

8.
ACS Appl Mater Interfaces ; 13(36): 43323-43332, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34469683

RESUMO

Conductive ionic hydrogel fibers and textiles with excellent mechanical properties and chemical stability are requested for flexible and wearable electronic devices, strain sensors, and even artificial skin. However, most of the reported hydrogel fibers are not suitable in complex environments, especially in alkaline solutions and organic solvents due to their poor chemical stability. Herein, we report ionic polyimide hydrogel fibers derived from an organosoluble polyimide salt that can be continuously and rapidly prepared via a facile wet spinning method. Thanks to their ion-rich property and robust skeletal structure, the obtained ionic polyimide hydrogel fibers showed an excellent conductivity of ∼21 mS/cm and outstanding mechanical properties with a tensile strength of 2.5 MPa and breaking elongation of 215%. Furthermore, the as-prepared fibers could be easily woven to form integral textiles, endowing them with good wearable properties. Accordingly, facile strain sensors assembled by polyimide hydrogel fibers show a linear response with high sensitivity and good cycling stability, which have great potential for applications in wearable and flexible strain sensors under diverse complex environments.

9.
ACS Sens ; 6(9): 3284-3294, 2021 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-34415145

RESUMO

We report a novel amperometric sensor for aqueous phosphate ions in freshwater systems based on the reductive square wave voltammetry of molybdate(VI) anions immobilized within a chitosan matrix deposited on a glassy carbon electrode. A sensitivity of 4.4 ± 0.1 µA/µM was realized together with a LOD of 0.15 µM. The sensor was insensitive to chloride and nitrate ions below a threshold concentration of 1.0 mM. Analytical measurements were successfully made in authentic samples of tap and pond water.


Assuntos
Fosfatos
10.
Plant Cell Rep ; 40(10): 1907-1922, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34322731

RESUMO

KEY MESSAGE: MsCML46 enhances tolerance to abiotic stresses through alleviating osmotic stress and oxidative damage by regulating the expression of stress-related genes to optimize osmolytes levels and antioxidant enzyme activity in transgenic tobacco. Abiotic stresses are major environmental factors that constraint crop productivity worldwide. Various stimuli regulate intracellular calcium levels and calcium-mediated signal transduction, and cellular responses. Ca2+ signals are perceived by different Ca2+ receptors. Calmodulin-like protein (CML) is one of the best-characterized Ca2+ sensors which shares sequence similarity with highly conserved calmodulin (CaM) ubiquitously expressed in plants. Currently, the molecular and physiological functions of CMLs are largely unknown. In this study, the MsCML46 was characterized in alfalfa (Medicago sativa cv. Zhaodong) under freezing stress. Results showed that MsCML46 was localized to the cytoplasm of Arabidopsis, and its expression was strongly elevated by cold, drought, salt, saline-alkali, and ABA treatments. Overexpressing MsCML46 in tobacco enhanced tolerance to freezing, drought, and salt stresses as evidenced by improved contents of osmotic regulatory solutes and antioxidant enzyme activity but decreased reactive oxygen species (ROS) accumulation. Furthermore, cold, drought, and salt stresses increased the expression of stress-related genes in transgenic tobacco. MsCML46 binds free Ca2+ to promote signal transduction and maintain higher K+/Na+ ratio. In this way, it protects intracellular homeostasis under sodium ion toxicity. These results suggest that MsCML46 plays a crucial role in resisting abiotic stresses and can be exploited in genetic engineering for crops.


Assuntos
Medicago sativa/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Tabaco/fisiologia , Antioxidantes/metabolismo , Calmodulina , Resposta ao Choque Frio/genética , Citoplasma/metabolismo , Secas , Enzimas/genética , Enzimas/metabolismo , Regulação da Expressão Gênica de Plantas , Peróxido de Hidrogênio/metabolismo , Filogenia , Plantas Geneticamente Modificadas , Estresse Salino/genética , Estresse Fisiológico , Tabaco/genética
11.
Biomed Opt Express ; 12(6): 3671-3683, 2021 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-34221687

RESUMO

Atopic dermatitis (AD) is a skin inflammatory disease affecting 10% of the population worldwide. Raster-scanning optoacoustic mesoscopy (RSOM) has recently shown promise in dermatological imaging. We conducted a comprehensive analysis using three machine-learning models, random forest (RF), support vector machine (SVM), and convolutional neural network (CNN) for classifying healthy versus AD conditions, and sub-classifying different AD severities using RSOM images and clinical information. CNN model successfully differentiates healthy from AD patients with 97% accuracy. With limited data, RF achieved 65% accuracy in sub-classifying AD patients into mild versus moderate-severe cases. Identification of disease severities is vital in managing AD treatment.

12.
Biosens Bioelectron ; 193: 113481, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34252705

RESUMO

Recently, nonmetallic substrates have stimulated great interest in surface-enhanced Raman scattering (SERS)-based immunoassay owing to their good uniformity, stability, and biocompatibility. In this context, a novel nonmetallic SERS-based immunoassay mediated by two-dimensional molybdenum disulfide (MoS2) was delivered for the sensitive and specific monitoring of carbohydrate antigen 19-9 (CA19-9). The effective enrichment of molecules on the large active surfaces of MoS2 as well as potential 532-nm laser-induced charge transfer resonances between them engendered desirable enhancement factor values at the level of 105. Intriguingly, a sandwich immunocomplex combined MoS2 nanoflower and nanosheet exhibited not only a wide linear range from 5 × 10-4 to 1 × 102 IU·mL-1 but also a limit of detection as low as 3.43 × 10-4 IU·mL-1 towards CA19-9. More meaningful, the analytical result for clinical patient serum sample was basically compared with the conventional chemiluminescent immunoassay. Such a novel nonmetallic SERS-based immunosensor with desirable biocompatibility and sensitivity is promising for clinical diagnosis.


Assuntos
Técnicas Biossensoriais , Molibdênio , Antígeno CA-19-9 , Carboidratos , Humanos , Imunoensaio , Análise Espectral Raman
13.
Front Microbiol ; 12: 663744, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34135875

RESUMO

Baijiu is an important fermented product in China. A yeast named YX3307 that is capable of producing a large amount of ethyl caproate (EC) was isolated from Daqu, a crude fermentation starter for Baijiu. This yeast was identified as Clavispora lusitaniae on the basis of its morphological properties, physiological and biochemical characteristics, and 26S rDNA sequence. Single-factor experiments were conducted to obtain the optimum fermentation conditions for EC production by YX3307. The highest EC yield (62.0 mg/L) from YX3307 was obtained with the following culture conditions: inoculum size 7.5% (v/v), seed cell age 30 h, sorghum hydrolysate medium (SHM) with a sugar content of 10 Brix and an initial pH of 6.0; incubation at 28°C with shaking at 180 rpm for 32 h; addition of 10% (v/v) anhydrous ethanol and 0.04% (v/v) caproic acid at 32 and 40 h, respectively, static culture at 20°C until 72 h. YX3307 synthesized more EC than ethyl acetate, ethyl lactate, ethyl butyrate, and ethyl octanoate. An intracellular enzyme or cell membrane enzyme was responsible for EC synthesis. YX3307 can produce many flavor compounds that are important for high-quality Baijiu. Thus, it has potential applications in improving the flavor and quality of Baijiu.

14.
Front Chem ; 9: 688320, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34150719

RESUMO

Semiconducting nanoparticles (SC NPs) play vital roles in several emerging technological applications including optoelectronic devices, sensors and catalysts. Recent research focusing on the single entity electrochemistry and photoelectrochemistry of SC NPs is a fascinating field which has attained an increasing interest in recent years. The nano-impact method provides a new avenue of studying electron transfer processes at single particle level and enables the discoveries of intrinsic (photo) electrochemical activities of the SC NPs. Herein, we review the recent research work on the electrochemistry and photoelectrochemistry of single SC NPs via the nano-impact technique. The redox reactions and electrocatalysis of single metal oxide semiconductor (MOS) NPs and chalcogenide quantum dots (QDs) are first discussed. The photoelectrochemistry of single SC NPs such as TiO2 and ZnO NPs is then summarized. The key findings and challenges under each topic are highlighted and our perspectives on future research directions are provided.

15.
Photoacoustics ; 22: 100268, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34026491

RESUMO

The ability to monitor oxygen delivery in microvasculature plays a vital role in measuring the viability of skin tissue and the probability of recovery. Using currently available clinical imaging tools, it is difficult to observe non-invasive hemodynamic regulation in the peripheral vessels. Here we propose the use of a novel multispectral raster-scanning optoacoustic mesoscopy (RSOM) system for noninvasive clinical monitoring of hemodynamic changes in the skin microvasculature's oxy- (HbO2) and deoxy-hemoglobin (Hb), total hemoglobin (HbT) and oxygen saturation (rsO2). High resolution images of hemoglobin distribution in the skin microvasculature from six healthy volunteers during venous and arterial occlusion, simulating systemic vascular diseases are presented. During venous occlusion, Hb and HbO2 optoacoustic signals showed an increasing trend with time, followed by a drop in the values after cuff deflation. During arterial occlusion, an increase in Hb value and decrease in HbO2 values was observed, followed by a drop in Hb and jump in HbO2 values after the cuff deflation. A decrease in rsO2 values during both venous and arterial occlusion was observed with an increase in value after occlusion release. Using this proof of concept study, hereby we propose multispectral RSOM as a novel tool to measure high resolution hemodynamic changes in microvasculature for investigating systemic vascular diseases on peripheral tissues and also for monitoring inflammatory skin diseases, and its therapeutic interventions.

16.
ACS Appl Mater Interfaces ; 13(9): 10972-10978, 2021 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-33641328

RESUMO

The electrocatalyzed oxygen and hydrogen evolution reactions (OER/HER) are the key constituents of water splitting toward hydrogen production over electrolysis. The development of stable non-noble nanomaterials as bifunctional OER/HER electrocatalysts is the foremost bottleneck to commercial applications. Herein, the fabrication of Te-modulated FeNiOOH nanocubes (NCs) by a novel tailoring approach is reported, and the doping of Te superbly modulated the local electronic structures of Fe and Ni. The Te/FeNiOOH-NC catalyst displays better mass and electron transfer ability, exposure of plentiful OER/HER edge active centers on the surface, and a modulated electronic structure. Accordingly, the as-made Te/FeNiOOH-NC catalyst reveals robust OER activity (overpotential of 0.22 V@10 mA cm-2) and HER activity (overpotential of 0.167 V@10 mA cm-2) in alkaline media. Considerably, this bifunctional catalyst facilitates a high-performance alkaline water electrolyzer with a cell voltage of 1.65 V at 10 mA cm-2. This strategy opens up a new way for designing and advancing the tellurium dopant nanomaterials for various applications.

17.
Food Chem Toxicol ; 151: 112111, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33716052

RESUMO

Biologically active peptides released by proteins are important in regulating immunity. The purpose of this study was to isolate and purify an immunologically active peptide from Hericium erinaceus (H. erinaceus) and to explore its effect on cytokine secretion and differentiation of macrophages. An active peptide with an amino acid sequence, Lys-Ser-Pro-Leu-Tyr (KSPLY) was obtained from H. erinaceus protein by ultrafiltration combined with multistage chromatography separation and identification technology. Subsequently, it was confirmed that the synthetic peptide KSPLY had a good immunomodulatory activity at a concentration of 100 µmol/L and could promote the secretion of NO, IL-1ß, IL-6 and TNF-α by macrophages. The effects of KSPLY on M1 macrophages and M2 macrophages were also studied. Results showed that KSPLY inhibited the secretion of NO and IL-6 by M1 macrophages and promoted the tendency of M2 macrophages to transform to M1 macrophages. Therefore, it can be concluded that KSPLY is an effective immunomodulatory peptide that may be beneficial in cancer treatment and human health improvement.


Assuntos
Adjuvantes Imunológicos/farmacologia , Hericium/química , Macrófagos/efeitos dos fármacos , Oligopeptídeos/isolamento & purificação , Proteínas de Plantas/química , Animais , Polaridade Celular/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Interleucina-1beta/metabolismo , Interleucina-6/metabolismo , Macrófagos/metabolismo , Camundongos , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Hidrolisados de Proteína/química , Células RAW 264.7 , Fator de Crescimento Transformador alfa/metabolismo
18.
Sci Rep ; 11(1): 4024, 2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33597656

RESUMO

Plant-specific WRKY transcription factors play important roles in regulating the expression of defense-responsive genes against pathogen attack. A multiple stress-responsive WRKY gene, ZmWRKY65, was identified in maize by screening salicylic acid (SA)-induced de novo transcriptomic sequences. The ZmWRKY65 protein was localized in the nucleus of mesophyll protoplasts. The analysis of the ZmWRKY65 promoter sequence indicated that it contains several stress-related transcriptional regulatory elements. Many environmental factors affecting the transcription of ZmWRKY65 gene, such as drought, salinity, high temperature and low temperature stress. Moreover, the transcription of ZmWRKY65 gene was also affected by the induction of defense related plant hormones such as SA and exogenous ABA. The results of seed germination and stomatal aperture assays indicated that transgenic Arabidopsis plants exhibit enhanced sensitivity to ABA and high concentrations of SA. Overexpression of ZmWRKY65 improved tolerance to both pathogen attack and abiotic stress in transgenic Arabidopsis plants and activated several stress-related genes such as RD29A, ERD10, and STZ as well as pathogenesis-related (PR) genes such as PR1, PR2 and PR5; these genes are involved in resistance to abiotic and biotic stresses in Arabidopsis. Together, this evidence implies that the ZmWRKY65 gene is involved in multiple stress signal transduction pathways.

19.
J Phys Chem Lett ; 12(5): 1567-1572, 2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33538591

RESUMO

The ligand/quantum dots (QDs) ratio is crucial for the liquid state ligand exchange process to ensure a high-quality surface passivation and stable QDs ink. Herein we report an electrochemical method to investigate the ligand exchanged PbS-PbI2 QDs. It is found that the shell and core Pb(II) are distinguished by their reduction peak position in the cyclic voltammogram and the peak charge ratio gives the shell/core composition of the QDs. Combined with XPS analysis and UV-vis spectroscopy, it is further indicated that the shell/core ratio of PbS-PbI2 QDs varies as the ligand PbI2 concentration changes. Specifically, below a certain concentration, more PbI2 binds to the QD surface, leading to better passivation when the PbI2 concentration increases; however, beyond that concentration, decomposition of QDs likely occurs via an anion exchange process. The presented electrochemical method provides a new and powerful tool to investigate and optimize QD surface chemistry for boosting the scale up applications of QD devices.

20.
Environ Pollut ; 273: 116461, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33485001

RESUMO

Phthalate ester pollution in the environment and food chain is frequently reported. Microbial treatment is a green and efficient method for solving this problem. The isolation and systematic investigation of microorganisms generally recognized as safe (GRAS) will provide useful resources. A GRAS Bacillus subtilis strain, BJQ0005, was isolated from Baijiu fermentation starter and efficiently degraded phthalate esters (PAEs). The half-lives for di-isobutyl phthalate, di-butyl phthalate and di-(2-ethylhexyl) phthalate were 3.93, 4.28, and 25.49 h, respectively, from the initial amount of 10 mg per 10 mL reaction mixture, which are records using wild-type strains. Genome sequencing and metabolic intermediate analysis generated the whole metabolic pathway. Eighteen enzymes from the α/ß hydrolase family were expressed. Enzymes GTW28_09400 and GTW28_13725 were capable of single ester bond hydrolysis of PAEs, while GTW28_17760 hydrolyzed di-ester bonds of PAEs. Using molecular docking, a possible mechanism affecting enzymatic ester bond hydrolysis of mono-butyl phthalate was proposed of GTW28_17760. The carboxyl group generated by the first hydrolysis step interacted with histidine in the catalytic active center, which negatively affected enzymatic hydrolysis. Isolation and systematic investigation of the PAE degradation characteristics of B. subtilis will promote the green and safe treatment of PAEs in the environment and food industry.

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