Nanoparticles as an antidote for poisoned gold single-atom catalysts in sustainable propylene epoxidation.

The development of sustainable and anti-poisoning single-atom catalysts (SACs) is essential for advancing their research from laboratory to industry. Here, we present a proof-of-concept study on the poisoning of Au SACs, and the antidote of Au nanoparticles (NPs), with trace addition shown to reinforce and sustain propylene epoxidation. Multiple characterizations, kinetics investigations, and multiscale simulations reveal that Au SACs display remarkable epoxidation activity at a low propylene coverage, but become poisoned at higher coverages. Interestingly, Au NPs can synergistically cooperate with Au SACs by providing distinct active sites required for H2/O2 and C3H6 activations, as well as hydroperoxyl radical to restore poisoned SACs. The difference in reaction order between C3H6 and H2 (nC3H6-nH2) is identified as the descriptor for establishing the volcano curves, which can be fine-tuned by the intimacy and composition of SACs and NPs to achieve a rate-matching scenario for the formation, transfer, and consumption of hydroperoxyl. Consequently, only trace addition of Au NPs antidote (0.3% ratio of SACs) stimulates significant improvements in propylene oxide formation rate, selectivity, and H2 efficiency compared to SACs alone, offering a 56-fold, 3-fold, and 22-fold increase, respectively, whose performances can be maintained for 150 h.

Feasibility of an oral health promotion program among older people in geriatric care facilities, Shanghai, China: a pre/post-implementation study.

BACKGROUND: The oral health of older people is closely related to their overall health. Timely and effective intervention in oral issues is necessary to maintain their overall health. This study aimed to evaluate the feasibility and effectiveness of an Oral Health Promotion Program (OHPP) in Geriatric Care Facilities (GCFs). METHODS: The OHPP was implemented in two GCFs and evaluated using a pre/post-design. Questionnaires on self-efficacy and attitude for providing oral care were sent to 42 nurse participants before and three months after the implementation of the OHPP. Outcomes of 295 patient participants were assessed at four time points (T1-baseline, T2-one month, T3-two months, and T4-three months post-implementation) including Activities of Daily Living (ADL), Mini-Mental State Examination (MMSE), and Oral Health Assessment Tool (OHAT). RESULTS: The oral health and daily activity ability of patient participants showed an improving trend at four time points pre/post-implementation of the OHPP. The proportion of patients with healthy mouths (OHAT: 0-3 points) increased from 29.8 to 67.8% and their scores of OHAT and ADL were significantly better at T4 compared to T1, T2, and T3 (p < 0.001). Self-efficacy (SE-PMC: T1 = 18.93 ± 3.18, T4 = 28.83 ± 6.56, p < 0.001) and attitude (A-PMC: T1 = 18.78 ± 3.09, T4 = 28.20 ± 6.03, p < 0.001) for oral care among nurse participants improved after the implementation of the OHPP. CONCLUSIONS: This study highlights the feasibility of implementing OHPP within GCFs, potentially enhancing the oral health and daily living activities of older individuals. Integrating the OHPP into routine care in geriatric settings is not only practical but also widely acceptable, offering a proactive approach to address oral health disparities among older residents. Stakeholders can maximize the impact of the OHPP by fostering collaboration among healthcare professionals, administrators, and residents, ultimately improving oral health outcomes and overall quality of life of older residents. TRIAL REGISTRATION: ChiCTR2000035236 (registration date: 04/08/2020).

Leveraging the Proximity and Distribution of Cu-Cs Sites for Direct Conversion of Methanol to Esters/Aldehydes.

Methanol serves as a versatile building-block for various commodity chemicals, and the development of industrially promising strategies for its conversion remains the ultimate goal in methanol chemistry. In this study, we design a dual Cu-Cs catalytic system that enables a one-step direct conversion of methanol and methyl acetate/ethanol into high value-added esters/aldehydes, with customized chain length and saturation by leveraging the proximity and distribution of Cu-Cs sites. Cu-Cs at a millimeter-scale intimacy triggers methanol dehydrogenation and condensation, involving proton transfer, aldol formation, and aldol condensation, to obtain unsaturated esters and aldehydes with selectivities of 76.3 % and 31.1 %, respectively. Cu-Cs at a micrometer-scale intimacy significantly promotes mass transfer of intermediates across catalyst interfaces and their subsequent hydrogenation to saturated esters and aldehydes with selectivities of 67.6 % and 93.1 %, respectively. Conversely, Cu-Cs at a nanometer-scale intimacy alters reaction pathway with a similar energy barrier for the rate-determining step, but blocks the acidic-basic sites and diverts the reaction to byproducts. More importantly, an unprecedented quadruple tandem catalytic production of methyl methacrylate (MMA) is achieved by further tailoring Cu and Cs distribution across the reaction bed in the configuration of Cu-Cs||Cs, outperforming the existing industrial processes and saving at least 15 % of production costs.

Biomineralization-powered integrated immunoprobe and its application in Immunochromatographic assay.

Immunochromatographic assay (ICA) has attracted widespread attention owing to its advantages of economy, simplicity, and rapidity. However, the synthesis of immunoprobes is still limited by complicated design ideas and multistep operations from preparing nanoparticles to conjugating monoclonal antibodies (mAb) onto nanoparticles. Inspired by the biomineralization of zeolitic imidazolate framework-8 (ZIF-8), we proposed a strategy for the rapid synthesis of an integrated immunoprobe (ZIF-8@QDs-mAb), achieving a one-step integration with strong fluorescent signal output capability and specific recognition ability. In addition, different fluorescent colors of ZIF-8@QDs-mAb were generated by doping red and green quantum dots (QDs) in various ratios. With a smart detection platform, the developed ZIF-8@QDs-mAb-based multiplex ICA (ZIF-8@QDs-mAb-mICA) achieved the on-site quantitative detection of enrofloxacin, sulfamethazine, and kanamycin in milk within 15 min, with the limit of detection (LOD) of 0.052, 0.186 and 0.216 ng mL-1, which were 5.69, 2.20 and 4.40 times higher than that of gold nanoparticles-based mICA, respectively. The quantitative detection of alpha-fetoprotein and human chorionic gonadotropin was also achieved with LOD of 0.516 ng mL-1 and 0.225 mIU mL-1, respectively, which verified the universality of the strategy. This work provides a novel idea for the design of an efficient integrated immunoprobe and has broad application prospects in ICA.

Decoding effects of psychoactive drugs in a high-dimensional space of eye movements in monkeys.

Oculomotor behavior has been shown to be correlated with mental disorders in clinics, making it promising for disease diagnosis. Here we developed a thorough oculomotor test toolkit, involving saccade, smooth pursuit, and fixation, allowing the examination of multiple oculomotor parameters in monkey models induced by psychoactive drugs. Eye movements were recorded after daily injections of phencyclidine (PCP) (3.0 mg/kg), ketamine (0.8 mg/kg) or controlled saline in two macaque monkeys. Both drugs led to robust reduction in accuracy and increment in reaction time during high cognitive-demanding tasks. Saccades, smooth pursuit, and fixation stability were also significantly impaired. During fixation, the involuntary microsaccades exhibited increased amplitudes and were biased toward the lower visual field. Pupillary response was reduced during cognitive tasks. Both drugs also increased sensitivity to auditory cues as reflected in auditory evoked potentials (AEPs). Thus, our animal model induced by psychoactive drugs produced largely similar abnormalities to that in patients with schizophrenia. Importantly, a classifier based on dimension reduction and machine learning could reliably identify altered states induced by different drugs (PCP, ketamine and saline, accuracy = 93%). The high performance of the classifier was reserved even when data from one monkey were used for training and testing the other subject (averaged classification accuracy = 90%). Thus, despite heterogeneity in baseline oculomotor behavior between the two monkeys, our model allows data transferability across individuals, which could be beneficial for future evaluation of pharmaceutical or physical therapy validity.

Factors associated with nurses' attitudes for providing oral care in geriatric care facilities: a cross-sectional study.

BACKGROUND: The world's population is getting older. This issue is accompanied by a rise in the number of older people suffering from dementia and disability, for whom oral hygiene care is challenging. Nurses' attitudes toward providing oral care (POC) are critical for the elderly, while few studies have investigated the determinant factors of nurses' attitudes by identifying the current work pressure, resilience and self-efficacy in geriatric care facilities (GCFs). It is of great significance to explore the nurses' attitudes toward POC and associated influencing factors related to psychological aspects including resilience, self-efficacy, and stress from the workplace. METHODS: Attitudes for Providing Mouth Care (A-PMC) in Chinese version were used in this cross-sectional study with 160 nurses in 2 GCFs. Data were collected using online questionnaires and analyzed by multiple linear regression analysis. Statistically significant values were considered at p < 0.05. RESULTS: A total of 160 nurses participated in this study, with an average age of 32.86 ± 7.43. The mean score for the A-PMC was 2.81 ± 0.47. The score of A-PMC was negatively correlated with work pressure (r=-0.332, p < 0.01), and positively correlated with resilience (r = 0.735, p < 0.01) and self-efficacy (r = 0.425, p < 0.01) respectively. Multiple linear regression analyses identified that the potential influencing factors of A-PMC were education background, work hours every shift, self-efficacy, work pressure and resilience. CONCLUSIONS: The study results indicate nurses' attitudes regarding PMC were at a low level, which is influenced by many factors. To improve nurses' attitudes toward PMC and the oral hygiene (OH) of the elderly in GCFs, it is necessary to increase nurses' education and training, establish a reasonable and effective incentive mechanism to improve nurses' work motivation and other intervention measures to reduce work pressure.

Synergistic Effect of Strontium and Melt Quenching on the Solidification Microstructure of Hypereutectic Al-Si Alloys.

The synergistic effect between strontium (Sr) and melt quenching on the solidified microstructure of hypereutectic Al-Si alloys was investigated by optical and scanning electron microscopy. The results indicate that melt quenching can suppress the growth of primary Si particles in the solidified structure of the hypereutectic Al-Si alloy, resulting in a significant decrease of in the average size of primary Si particles in Al-(18~22)Si alloys from 30.35~66.31 µm to 15.13~34.63 µm. The synergistic effect between Sr and melt quenching can further inhibit the precipitation of primary Si particles in the Al-18Si alloy. After the addition of Sr to Al-18Si alloy and undergoing melt quenching, the area fraction of primary Si clearly decreases. When the added amount of Sr increases from 0.1 wt.% to 0.5 wt.%, the area fraction of primary Si decreases from 1.13% to 0.16%. With 0.5 wt.% Sr in the tested alloy, the inhibiting effect on primary Si precipitation was significantly improved. Research has shown that the cooling rate has a significant impact on the solidified structure of the melt-quenched Al-18Si-0.5Sr alloy. There exists no primary Si in solidified structures on the area of 1/8R and 1/4R from the surface of the round bar sample, but the area fraction of primary Si increases, respectively, to 1.97% and 12.48% on the area of 1/2R and R from the surface. The higher the cooling rate, the higher the inhibitory effect on the primary Si precipitation in the Al-18Si-0.5Sr alloy.

Research status, hotspots and trends on oral care research in the elderly published from 2002 to 2022: A bibliometric analysis - A review article.

AIMS: The aim of this study was to analyse the status, hotspots and trends of research on oral care for the elderly in mainland China in the past 20 years through bibliometrics, which aims to provide new ideas and targets for future clinical work and research. DESIGN: Bibliometric analysis. METHODS: Relevant literature was retrieved from China National Knowledge Infrastructure, Wanfang, China Science and Technology Journal Database, Web of Science and PubMed. NoteExpress, Co-Occurrence and CiteSpace were used to analyse bibliometric features in terms of year of publication, journal of publication, authors, institution and keywords. RESULTS: A total of 716 related articles were obtained. The number of publications shows an increasing trend over time, only 2017-2021; 309 papers were published, accounting for 43.2% of the total number of publications. A total of 238 articles were published in Science Citation Index journals or Chinese core journals, accounting for 33.2% of the total number of articles. The study of oral health-related quality of life in the elderly is a hot research topic. There is a lack of research on the elderly living in elderly care facilities.

Dual Microenvironment Modulation of Pd Nanoparticles in Covalent Organic Frameworks for Semihydrogenation of Alkynes.

The chemical microenvironment modulation of metal nanoparticles (NPs) holds promise for tackling the long-lasting challenge of the trade-off effect between activity and selectivity in catalysis. Herein, ultrafine PdCu2 NPs incorporated into covalent organic frameworks (COFs) with diverse groups on their pore walls have been fabricated for the semihydrogenation of alkynes. The Cu species, as the primary microenvironment of Pd active sites, greatly improves the selectivity. The functional groups as the secondary microenvironment around PdCu2 NPs effectively regulate the activity, in which PdCu2 NPs encapsulated in the COF bearing -CH3 groups exhibit the highest activity with >99 % conversion and 97 % selectivity. Both experimental and calculation results suggest that the functional group affects the electron-donating ability of the COFs, which successively impacts the charge transfer between COFs and Pd sites, giving rise to a modulated Pd electronic state and excellent catalytic performance.

Ruthenium/TiO2 -Catalyzed Hydrogenolysis of Polyethylene Terephthalate: Reaction Pathways Dominated by Coordination Environment.

Polyethylene terephthalate (PET) hydrogenolysis can produce benzene, toluene, and xylene (BTX), where the selectivity control is challenging. We report a reaction pathway dictated by the Ru coordination environment by examining the binding geometries of adsorbates on differently coordinated Ru centers and their evolution during PET hydrogenolysis. A BTX yield of 77 % was obtained using a Ru/TiO2 with a Ru coordination number of ca. 5.0 where edge/corner sites are dominant, while more gas and saturated products were formed for Ru/TiO2 containing primarily terrace sites. Density functional theory and isotopic labelling revealed that under-coordinated Ru edge sites favor "upright" adsorption of aromatic adsorbates while well-coordinated Ru sites favor "flat-lying" adsorption, where the former mitigates ring hydrogenation and opening. This study demonstrates that reaction pathways can be directed through controlled reactant/intermediate binding via tuning of the Ru coordination environment for efficient conversion of PET to BTX.

Self-efficacy and attitudes of nurses providing oral care in geriatric care facilities: A cross-sectional study in Shanghai.

AIMS: To investigate nurses' self-efficacy and attitudes of providing oral care in geriatric care facilities (GCFs) and compare differences between individuals, facilities and countries. DESIGN: A cross-sectional and multicentre study. METHODS: Data were collected from 852 nurses in 42 GCFs using two scales, "Self-Efficacy for Providing Mouth Care" (SE-PMC) and "Attitudes for Providing Mouth Care" (A-PMC), and analysed using t-test and ANOVA. RESULTS: Totally 852 nurses (844 females, 99%) participated in this study with an effective response rate of 85.2%. Scores of SE-PMC and A-PMC of nurses varied significantly among GCFs with different sizes, types and years of establishment and differentiated among staff about the length of employment (p < .05). Nurses (N = 434) in North Carolina scored higher than nurses in Shanghai both in SE-PMC and A-PMC (p < .05). Establishment and implementation of Oral health promotion programmes were desired based on characteristics of different institutions and nurses' clinical ladder.

Mesokinetics as a Tool Bridging the Microscopic-to-Macroscopic Transition to Rationalize Catalyst Design.

Heterogeneous catalysis is the workhorse of the chemical industry, and a heterogeneous catalyst possesses numerous active sites working together to drive the conversion of reactants to desirable products. Over the decades, much focus has been placed on identifying the factors affecting the active sites to gain deep insights into the structure-performance relationship, which in turn guides the design and preparation of more active, selective, and stable catalysts. However, the molecular-level interplay between active sites and catalytic function still remains qualitative or semiquantitative, ascribed to the difficulty and uncertainty in elucidating the nature of active sites for its controllable manipulation. Hence, bridging the microscopic properties of active sites and the macroscopic catalytic performance, that is, microscopic-to-macroscopic transition, to afford a quantitative description is intriguing yet challenging, and progress toward this promises to revolutionize catalyst design and preparation.In this Account, we propose mesokinetics modeling, for the first time enabling a quantitative description of active site characteristics and the related mechanistic information, as a versatile tool to guide rational catalyst design. Exemplified by a pseudo-zero-order reaction, the kinetics derivation from the Pt particle size-sensitive catalytic activity and size-insensitive activation energy suggests only one type of surface site as the dominant active site, in which the Pt(111) with almost unchanged turnover frequency (TOF111) is further identified as the dominating active site. Such a method has been extended to identify and quantify the number (Ni) of active sites for various thermo-, electro-, and photocatalysts in chemical synthesis, hydrogen generation, environment application, etc. Then, the kinetics derivation from the kinetic compensation effects suggests a thermodynamic balance between the activation entropy and enthalpy, which exhibit linear dependences on Pt charge. Accordingly, the Pt charge can serve as a catalytic descriptor for its quantitative determination of TOFi. This strategy has been further applied to Pt-catalyzed CO oxidation with nonzero-order reaction characteristic by taking the site coverages of surface species into consideration.Hence, substituting the above statistical correlations of Ni and TOFi into the rate equation R = ∑Ni × TOFi offers the mesokinetics model, which can precisely predict catalytic function and screen catalysts. Finally, based on the disentanglement of the factors underlying Pt electronic structures, a de novo strategy, from the interfacial charge distribution to reaction mechanism, kinetics, and thermodynamics parameters of the rate-determining step, and ultimately catalytic performance, is developed to map the unified mechanistic and kinetics picture of reaction. Overall, the mesokinetics not only demonstrates much potential to elucidate the quantitative interplay between active sites and catalytic activity but also provides a new research direction in kinetics analysis to rationalize catalyst design.

Remodeling nanodroplets into hierarchical mesoporous silica nanoreactors with multiple chambers.

Multi-chambered architectures have attracted much attention due to the ability to establish multifunctional partitions in different chambers, but manipulating the chamber numbers and coupling multi-functionality within the multi-chambered mesoporous nanoparticle remains a challenge. Herein, we propose a nanodroplet remodeling strategy for the synthesis of hierarchical multi-chambered mesoporous silica nanoparticles with tunable architectures. Typically, the dual-chambered nanoparticles with a high surface area of ~469 m2 g-1 present two interconnected cavities like a calabash. Furthermore, based on this nanodroplet remodeling strategy, multiple species (magnetic, catalytic, optic, etc.) can be separately anchored in different chamber without obvious mutual-crosstalk. We design a dual-chambered mesoporous nanoreactors with spatial isolation of Au and Pd active-sites for the cascade synthesis of 2-phenylindole from 1-nitro-2-(phenylethynyl)benzene. Due to the efficient mass transfer of reactants and intermediates in the dual-chambered structure, the selectivity of the target product reaches to ~76.5%, far exceeding that of single-chambered nanoreactors (~41.3%).

Translation, cross-cultural adaptation, and validation of the Chinese version of self-efficacy and attitudes for providing Mouth Care scale.

BACKGROUND: In recent years, oral care for older people has received extensive attention in long-term care facilities. The Self-Efficacy for Providing Mouth Care (SE-PMC) and Attitudes for Providing Mouth Care (A-PMC) scale evaluated the self-efficacy and attitude of nursing staff while providing oral care. However, whether this scale is valid and reliable for Chinese nursing staff in China remains unverified. This study aims to translate the English version of SE-PMC and A-PMC into Chinese and determine their reliability and validity. METHODS: After obtaining the author's consent, the procedure for a double-back translation and cross-cultural adaptation was conducted to develop the Chinese version of SE-PMC and A-PMC. The validity and reliability of the Chinese version of SE-PMC and A-PMC were evaluated in a cross-sectional observational study with 852 nurses from 42 Geriatric Care Facilities (GCFs). Exploratory factor analysis (EFA) (n = 427) and confirmatory factor analysis (CFA) (n = 425) were conducted to test the construct validity and quality of the factor structures. We applied the item discrimination test and homogeneity test for item analysis. Cronbach's alpha coefficient and split-half coefficient were adopted to evaluate internal consistency. RESULTS: The Chinese version of SE-PMC (11 items, 3 factors) and A-PMC (11 items, 2 factors) included 22 items, reflecting adequate construct validity and reliability. In addition, test-retest reliability was 0.809 for SE-PMC and 0.811 for A-PMC, evincing good stability. The Cronbach's α coefficient of SE-PMC was 0.831, with each factor ranging from 0.793~0.906. The Cronbach's α coefficient of the A-PMC was 0.768, with each factor ranging from 0.814~0.824. Item-Content Validity Index (I-CVI) of SE-PMC and A-PMC ranged from 0.84 ~1.00 and 0.82~1.00, respectively. CONCLUSION: The Chinese version of SE-PMC and A-PMC was validated as a reliable assessment tool to evaluate the self-efficacy and attitude of nursing staff in GCFs for providing oral care in China.

Molecular-Level Insights into the Notorious CO Poisoning of Platinum Catalyst.

Carbon monoxide (CO) is notorious for its strong adsorption to poison platinum group metal catalysts in the chemical industry. Here, we conceptually distinguish and quantify the effects of the occupancy and energy of d electrons, emerging as the two vital factors in d-band theory, for CO poisoning of Pt nanocatalysts. The stepwise defunctionalization of carbon support is adopted to fine-tune the 5d electronic structure of supported Pt nanoparticles. Excluding other promotional mechanisms, the increase of Pt 5d band energy strengthens the competitive adsorption of hydrogen against CO for the preferential oxidation of CO, affording the scaling relationship between Pt 5d band energy and CO/H2 adsorption energy difference. The decrease of Pt 5d band occupancy lowers CO site coverage to promote its association with oxygen for the total oxidation of CO, giving the scaling relationship between Pt 5d occupancy and activation energy. The above insights outline a molecular-level understanding of CO poisoning.

I2/I--mediated fluorescence quenching of an Ag+-doped gold nanocluster-based immunoassay for sensitive detection of Escherichia coli O157:H7 in milk.

Escherichia coli O157:H7 is a type of hazardous bacteria in the field of food safety. A sensitive and effective method is urgently needed to detect it, avoiding enormous harm for the human health. In this study, we synthesized stable Ag+-doped gold nanoclusters (Ag-AuNC) with a fluorescence intensity 4.8 times stronger than that of AuNC. It was further demonstrated that Ag0 existing in the AuNC core and a fraction of Ag+ anchored on the AuNC shell eliminated the surface defects and improved the luminescent properties of AuNC. A combination of I2 and I- was used to quench fluorescence-enhanced Ag-AuNC, which was first applied in ELISA for detecting E. coli O157:H7 to improve the sensitivity. In the presence of E. coli O157:H7, the biotinylated anti-E. coli O157:H7 mAb and streptavidin-alkaline phosphatase would be immobilized and catalyze l-ascorbic acid 2-phosphate sesquimagnesium salt hydrate to produce ascorbic acid. After addition of KIO3, I2/I- were generated. The I2 could trigger oxidative etching of Ag-AuNC and I- could combine with Ag+ to decrease the Ag+ concentration of Ag-AuNC, which resulted in fluorescence quenching of Ag-AuNC. Under optimal conditions, the linear range of I2/I--mediated fluorescence quenching of Ag-AuNC-based immunoassay for detecting E. coli O157:H7 was 3.3 × 103 to 106 cfu/mL, with a detection limit of 9.2 × 102 cfu/mL, 10.7-fold lower than that of the traditional ELISA. The proposed immunoassay exhibits excellent sensitivity, specificity, recovery, and accuracy, which is useful for quantitative detection of E. coli O157:H7 in food safety.

100+ FPS detector of personal protective equipment for worker safety: A deep learning approach for green edge computing.

In industrial production, personal protective equipment (PPE) protects workers from accidental injuries. However, wearing PPE is not strictly enforced among workers due to all kinds of reasons. To enhance the monitoring of workers and thus avoid safety accidents, it is essential to design an automatic detection method for PPE. In this paper, we constructed a dataset called FZU-PPE for our study, which contains four types of PPE (helmet, safety vest, mask, and gloves). To reduce the model size and resource consumption, we propose a lightweight object detection method based on deep learning for superfast detection of whether workers are wearing PPE or not. We use two lightweight methods to optimize the network structure of the object detection algorithm to reduce the computational effort and parameters of the detection model by 32% and 25%, respectively, with minimal accuracy loss. We propose a channel pruning algorithm based on the BN layer scaling factor γ to further reduce the size of the detection model. Experiments show that the automatic detection of PPE using our lightweight object detection method takes only 9.5 ms to detect a single video frame and achieves a detection speed of 105 FPS. Our detection model has a minimum size of 1.82 MB and a model size compression rate of 86.7%, which can meet the strict requirements of memory occupation and computational resources for embedded and mobile devices. Our approach is a superfast detection method for green edge computing.

Development of a label-free plasmonic gold nanoparticles aggregates sensor on the basis of charge neutralization for the detection of zearalenone.

Mycotoxin contamination of corn has been considered a serious problem because it can accumulate in different organs or tissues via ingestion or skin contact and cause several health problems in humans. We have constructed a label-free, colorimetric, and fluorescence dual-channel sensing platform for the detection of zearalenone. Here, we demonstrate that plasmonic gold nanoparticles aggregates could be rapidly formed on the basis of charge neutralization by positively charged SYBR Green I. The sensing platform allowed quantitative detection as low as 0.89 µg kg-1 and visual detection as low as 2.5 µg kg-1. The charge neutralization strategy eliminates a major source of instability in conventional gold nanoparticles colorimetric measurements and paves the way for accurate, label-free bioanalysis.

Molecular-level insights into the electronic effects in platinum-catalyzed carbon monoxide oxidation.

A molecular-level understanding of how the electronic structure of metal center tunes the catalytic behaviors remains a grand challenge in heterogeneous catalysis. Herein, we report an unconventional kinetics strategy for bridging the microscopic metal electronic structure and the macroscopic steady-state rate for CO oxidation over Pt catalysts. X-ray absorption and photoelectron spectroscopy as well as electron paramagnetic resonance investigations unambiguously reveal the tunable Pt electronic structures with well-designed carbon support surface chemistry. Diminishing the electron density of Pt consolidates the CO-assisted O2 dissociation pathway via the O*-O-C*-O intermediate directly observed by isotopic labeling studies and rationalized by density-functional theory calculations. A combined steady-state isotopic transient kinetic and in situ electronic analyses identifies Pt charge as the kinetics indicators by being closely related to the frequency factor, site coverage, and activation energy. Further incorporation of catalyst structural parameters yields a novel model for quantifying the electronic effects and predicting the catalytic performance. These could serve as a benchmark of catalyst design by a comprehensive kinetics study at the molecular level.