Nicotine (3-(1-methyl-2-pyrrolidinyl)pyridine) is one of the most common addictive substances, causing the trace detection of nicotine to be very necessary. Herein, we designed and prepared a ...functionalized nanocomposite CS-PAA (NaYF
4
:19.5%Yb,0.5%Tm@NaYF
4
-PAA) using a simple method. The nicotine concentration was quantitatively detected through the inhibition of choline oxidase activity by nicotine and the luminescence intensity of CS-PAA being quenched by Fe
3+
. The mechanism of Fe
3+
quenching CS-PAA emission was inferred by luminescence lifetime and UV–vis absorption spectra characterization. During the nicotine detection, both excitation (980 nm) and emission (802 nm) wavelengths of CS-PAA enable the avoidance of the interference of background fluorescence in complicated food objects, thus providing high selectivity and sensitivity with a linear range of 5–750 ng/mL and a limit of detection of 9.3 nM. The method exhibits an excellent recovery and relative standard deviation, indicating high accuracy and repeatability of the detection of nicotine.
Graphical abstract
Magnetic Fe–Fe
3
O
4
/UiO-66 was prepared by hydrogen reduction method and used as the catalyst for catalytic transfer hydrogenation of furfural to furfuryl alcohol with alcohol as the hydrogen ...donor. The preparation parameters of Fe–Fe
3
O
4
/UiO-66 and the effects of reaction conditions on catalytic transfer hydrogenation of furfural were studied in detail. Fe
3
O
4
, elementary iron (Fe), and Fe–Fe
3
O
4
mixture from the corresponding iron oxide (Fe
x
O
y
) active components can be formed by controlling the reducing temperature. Compared with UiO-66, when Fe
x
O
y
is a Fe–Fe
3
O
4
mixture, the resulting Fe–Fe
3
O
4
/UiO-66 shows the highest activity in catalytic transfer hydrogenation of furfural. Furthermore, Fe–Fe
3
O
4
/UiO-66 is easy to separate by a magnetic field and exhibits excellent catalytic recycling performance.
Titanium dioxide (TiO2) composites are popular photocatalysts for hydrogen production from water. Here we report a composite consisting of S and N co-doped graphene quantum dots (SN-GQDs) with ...(001)TiO2 for photocatalytic hydrogen production. In addition to traditional advantages like light absorption promotion and charge transfer improvement, the as-prepared SN-GQDs/(001)TiO2 composite could significantly enhance the surface reaction by promotion of the formation of hydroxyl radicals, which results in the increase of the hydrogen production activity by 40 times. This work reveals the importance of surface reaction promotion by GQDs for hydrogen production, which will help researchers understand relevant systems comprehensively.
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•SN-GQD enhances the hydrogen production activity of (001)TiO2 by 40-fold.•SN-GQD promotes both charge separation and surface reaction for H2 production.•SN-GQD facilitates generation of ·OH and consumption of water.
Using the financial data of listed Chinese companies, we study the impact of COVID-19 on corporate performance. We show that COVID-19 has a negative impact on firm performance. The negative impact of ...COVID-19 on firm performance is more pronounced when a firm's investment scale or sales revenue is smaller. We show, in an additional analysis, that the negative impact of COVID-19 on firm performance is more pronounced in serious-impact areas and industries. These findings are among the first empirical evidence of the association between pandemic and firm performance.
The COVID-19 outbreak seriously affected all economies, especially the operations of listed companies, around the world. This article studies the impact of COVID-19 on firm-level cash holdings using ...the difference-in-differences method. It finds that COVID-19 has a significant positive impact on cash holdings in serious-impact industries. Goodwill and goodwill impairment can weaken this positive impact, which may be related to higher business risks in these firms. Therefore, managers should raise firms' cash holding level during the pandemic to protect firms against contingencies. Managers should also be aware of financing constraints due to risks.
To explore the potential correlation between the amount and source of dietary protein and cardiovascular disease (CVD), as well as the potential impact of genetic susceptibility on these connections.
...We performed a prospective analysis of 98,224 participants from the UK. We measured dietary protein intake using two 24-hour dietary recall interviews. To analyze the data, we used multivariable-adjusted Cox regression models and restricted cubic spline models. Additionally, we calculated weighted genetic risk scores.
A total of 8818 new cases of CVD were documented, which included 4076 cases of coronary artery disease (CAD) and 1126 cases of stroke. The study found a J-shaped association (p nonlinearity = 0.005) between CVD risk and the percentage of energy obtained from consuming plant protein. Higher intake of plant protein and whole protein was associated with a decreased risk of CVD. On the other hand, larger intakes of animal protein was linked to a higher occurrence of CAD. Additionally, increased intake of plant protein was also linked to a lower incidence of stroke. Replacing 5 % of animal protein-based energy intake with plant protein-based energy intake resulted in a 5 % decrease in CVD risk.
There remains an effect of residual confounders.
The consumption of larger amounts of plant protein, whole protein, and nut protein was found to be associated with a lower risk of CVD events. Conversely, higher intakes of animal protein was associated with an increased risk of CAD events. Furthermore, replacing 5 % of energy intake from animal protein with energy intake from plant protein was found to reduce the risk of CVD by 5 %.
•Larger intakes of plant protein, whole protein, and nut protein were linked to fewer CVD and CAD events.•Higher total and animal protein intakes were linked to more CAD events.•Replacing 5 % of animal protein energy intake with plant protein-based energy intake reduced CVD risk by 5 %.
•Fe3O4-CG nanospheres was synthesized via one-step hydrothermal strategy.•Fe3O4-CG nanospheres showed high selectivity, sensitivity and stable reusability.•180 glycopeptides were identified by ...Fe3O4-CG nanospheres.•Fe3O4-CG nanospheres had fine potential for early diagnosis of Alzheimer's disease.
A novel ultra-hydrophilic zwitterionic-HILIC (ZIC-HILIC) nanosphere (Fe3O4-CG) was synthesized via a one-step hydrothermal strategy, which significantly simplified the conventional multi-step procedures for the preparation of ZIC-HILIC materials. The dual-functional Fe3O4-CG nanosphere exhibited excellent selectivity (molar ratio BSA:HRP = 5000:1), low detection limit (0.05 fmol/μL), satisfactory reusability (at least 5 times) and recovery rate (93.7 ± 2.1%). The binding constant of Fe3O4-CG for HRP is 2.45 ± 0.32 × 10−6 M and the theoretical binding capacity is 330 mg g−1. In addition, the Fe3O4-CG microsphere showed excellent performance in the detection of glycopeptides from real biological samples. Furthermore, 131 glycopeptides related to 71 glycoproteins were selectively enriched from healthy human serum and 180 glycopeptides related to 82 glycoproteins were captured from Alzheimer's disease patients' serum analyzed by Nano-LC-MS/MS. Gene ontology analysis of the biological process and molecular function showed that 21 primitive glycoproteins in glycopeptides captured from Alzheimer's disease patients' serum were meaningfully involved in a variety of neurodegenerative disease-related events, including serine-type endopeptidase inhibitor activity, receptor binding, positive regulation of B cell activation, and platelet activation.
Microwave resonators combined with polymer absorption layers are widely used in volatile organic compound (VOC) detection based on their variable resonant frequencies. However, the response time is ...limited due to the polymer’s slow volumetric absorption of VOC molecules. By constructing a porous structure in Polydimethylsiloxane (PDMS), resulting in reduced the response time to as short as 71.1%. To mitigate the sensitivity decline caused by the porous PDMS, a trenched-substrate complementary split-ring resonator (CSRR) is proposed for enhancing the interaction between the electromagnetic fields (EMFs) and the porous PDMS with VOCs. The removal of the substrate beneath CSRR’s sensing region enhances the effective EMF, increasing frequency and amplitude sensitivities up to 175.5% and 137.8%, respectively. Responses to four common VOCs by the sensor show a maximum sensitivity of 217 Hz/ppm and a minimum limit of detection of 295 ppm. Additionally, resonant parameters and extracted lumped parameters are utilized to establish two decision-tree-based VOC classification models, achieving high accuracies of 98.71% and 99.59%, respectively. And the latter one fully utilizing responses throughout the swept band, proves superior in identifying similar substances. This sensor technology helps promote the sensitive detection and accurate classification of diverse VOCs.
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•The improving response speed owing to the porous structure of the absorption layer.•The improving sensitivity by structural optimization involving the reduction of resonator’s substrate capacitance.•Linear detection of VOCs within a wide concentration range from 102 to 104 ppm.•Multiple VOCs classification with a high accuracy of 99.59%.
•mTiO2@AuCG can simultaneous/separate enrich glycopeptides and phosphopeptides.•mTiO2@AuCG showed high selectivity, low limit of detection, fine recovery rate.•167 glyco- and 14 phosphopeptides were ...detected from Alzheimer's disease patient.•mTiO2@AuCG may be beneficial for exploration Alzheimer's disease pathogenesis.
Alzheimer's disease (AD) is a common neurodegenerative disease. Abnormal glycosylation and phosphorylation modification in AD may be closely related to its pathology. It is of substantial practical significance to simultaneously investigate the roles of phosphorylation and glycosylation in AD. In this work, a bifunctional super-hydrophilic mesoporous nanocomposite (denoted mTiO2@AuCG) was prepared, which combined hydrophilic interaction chromatography (HILIC) and metal oxide affinity chromatography (MOAC) enrichment strategies to enrich phosphopeptides and glycopeptides, respectively or simultaneously. The mTiO2@AuCG exhibited excellent performance on the high-efficiency enrichment of glycopeptides (selectivity, 5000:1 molar ratios of BSA/HRP; sensitivity, 0.1 fmol HRP; satisfactory recovery rate; loading capacity, 200 mg/g) and phosphopeptides (selectivity, 1000:1 molar ratios of BSA/β-casein; sensitivity, 0.2 fmol β-casein; satisfactory recovery rate; loading capacity, 200 mg/g). Using these advantages, after single-step enrichment of mTiO2@AuCG, a total of 209 glycopeptides related to 93 glycoproteins, and 17 phosphopeptides related to 13 phosphoproteins were detected from normal human serum. By contrast, 167 glycopeptides related to 88 glycoproteins, and 14 phosphopeptides related to 12 phosphoproteins were found in AD serum.
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