High-Efficiency Ce3+ Activated Orthorhombic Lanthanide Silicate Blue Phosphors for Plant Growth Lighting.

Plant growth can be controlled and freed from natural environmental interference through indoor plant cultivation. Artificial light sources with better quality are required to promote indoor plant growth. In this study, we used a simple high-temperature solid-state reaction to synthesize high-efficiency Ce3+-activated NaGdSiO4 (NGSO) phosphors. X-ray diffraction and Rietveld refinement were performed to determine the detailed crystal structure of the NGSO:Ce3+ phosphors. The morphology of NGSO:Ce3+ and the elemental state of Ce3+ were measured and analyzed. Under near-ultraviolet (n-UV) light excitation, the Ce3+-activated NGSO phosphors exhibit a broad emission band from 375 to 500 nm, and their emission peaks are at approximately 401 nm. This asymmetrical blue emission band is caused by the spin-allowed 5d → 4f transition of Ce3+ and overlaps well with the blue absorption region of carotenoids and chlorophyll. The temperature-dependent luminescence spectra were utilized to assess the thermal stability of NGSO:Ce3+. The external quantum efficiency (EQE) was measured to be 60.91%, and the internal quantum efficiency (IQE) was measured to be 73.39%. A blue LED device assembled from the NGSO:Ce3+ phosphor has demonstrated the application potential in accelerating plant growth.

Exploring the pH Sensitivity of Ion-Pair Interactions on a Self-Assembled Monolayer by Scanning Electrochemical Microscopy.

Insights into the chemical essence of weak interactions on the surface of biomacromolecules may help to regulate biological processes. In this work, the pH sensitivity of ion-pair interactions occurring on a cysteine self-assembled monolayer (Cys SAM) that simulates the local surface of a protein was probed by scanning electrochemical microscopy (SECM). Cys SAM and the ion-pair interactions subsequently formed with the introduced aspartic acid (Asp) were both pH-sensitive, as confirmed by the tip current changes in the feedback mode. After continuous pH measurements, the most significant negative feedback was observed at pH 5.50, indicating the most robust ion-pair interactions, which were simultaneously identified by voltammetry. In this case, the extra addition of the inorganic cation (i.e., Ca2+) did not disrupt the existing ion-pair interactions, and the binding constant (K) and Gibbs free energy (ΔGo) of the ion pair were finally determined to be 6.44 × 105 M-1 and -33.14 kJ mol-1, respectively. Overall, the pH sensitivity of ion-pair interactions was found to be mainly attributable to pH-induced changes in the deprotonated/protonated states of the α-amino acid moieties, which may provide insights into the artificial manipulation of complex binding events at the molecular level on the biological surface.

Eu2+-activated MgAl2Si4O6N4: a novel oxonitridoalumosilicate blue phosphor for white LEDs.

Recently, blue-emitting phosphors have attracted great interest due to their application in full-spectrum white light illumination. In this paper, a novel blue-emitting MgAl2Si4O6N4:Eu2+ phosphor was successfully synthesized through the solid-state reaction method in a reducing atmosphere. Under the excitation of near-ultraviolet (n-UV) light, the MgAl2Si4O6N4:0.02Eu2+ phosphor effectively emits a broad blue emission band centered at 456 nm with the FWHM as large as 81 nm. With the increasing Eu2+ concentration, the emission bands of MgAl2Si4O6N4:Eu2+ shift to a shorter wavelength and the FWHMs broaden gradually. Moreover, the MgAl2Si4O6N4:0.02Eu2+ phosphor exhibits a slight thermal quenching at a higher temperature. After fabricating the as-prepared MgAl2Si4O6N4:0.02Eu2+ phosphor into a white LED device, the intense neutral white light emission is obtained with excellent CRI (87.4) and CCT (5645 K). These results suggest that the blue MgAl2Si4O6N4:Eu2+ phosphor is a promising candidate in n-UV excited white LEDs.

Intermolecular hydrogen bonds between catechin and theanine in tea: slow release of the antioxidant capacity by a synergetic effect.

The health benefits of drinking tea stem from it being rich in polyphenols and other physiologically-active substances. Thus, exploring the synergistic effect between polyphenols and a variety of physiologically-active substances can contribute to our understanding of how tea benefits health. In this work, we have studied the interactions between catechin and theanine, exploring the synergetic antioxidant mechanism of the two molecules. Electrochemical characterization results showed that the oxidation peak current of catechin decreased gradually with the concentration of theanine, which is due to theanine spontaneously binding to catechin through intermolecular hydrogen bonds and forming molecular clusters via two hydrogen bonds. The binding constant is 4.75 at room temperature. The molecular clusters reduce the diffusion coefficient of catechin in solution, leading to the slow release of its antioxidant capacity (ability to effectively inhibit free radical oxidation reactions). Density functional theory calculations were also performed and verified the binding behavior. In identifying the synergistic effect between catechin and theanine on the antioxidant capacity of tea, this study adds to our understanding of the efficacy of tea polyphenols.

Proton-coupled electron transfer of catechin in tea wine: the enhanced mechanism of anti-oxidative capacity.

Tea wine is a Chinese traditional alcoholic drink made by cereal and tea leaves. It is rich in tea polyphenols, caffeine, amino acids, and protons and possesses various healthcare functions. In this work, electrochemical methods, as well as density functional theory (DFT) calculations, were adopted to reveal the proton-coupled electron-transfer process of catechin in tea wine. The electrochemical results showed that the catechin preferred hydrogen-bonding with ethanol and formed molecular clusters. Thus, the direct electron-transfer process of catechin changed to proton-coupled electron transfer. This procedure reduced the energy barrier of the redox reaction and enhanced the anti-oxidative capacity. Subsequently, DFT calculations were employed to explore the bond length, bond energy, and HOMO-LUMO energy gap of catechin, which confirmed the above-mentioned mechanism. Our work offers some positive value for the scientific promotion of traditional food and a greater understanding of the health mechanisms in terms of chemistry.

Controllable release of dopamine from simulated enzyme-containing biomembrane by biased potential.

Controllable release of dopamine (DA) is worth studying for its significant in physiological metabolic process. ß-cyclodextrin/11-mercaptoundecanoic acid self-assembled monolayer (ß-CD/MUA SAM) based on hydrogen bonds network was constructed as simulated enzyme-containing biomembrane. DA interacted with ß-CD based on intermolecular hydrogen bond and formed inclusion complexes in SAM, namely DA@ß-CD/MUA SAM. The desorption process of DA from DA@ß-CD/MUA SAM revealed the release behavior of DA from enzyme-containing biomembrane at molecular level. Positive biased potential as external stimulus was applied at DA@ß-CD/MUA SAM, reducing the negative charge density of SAM. The decrease of negative charge density of SAM resulted in the weakening of hydrogen bond between DA and ß-CD, which in turn caused DA to be released. Using scanning electrochemical microscopy, positive biased potential not only had specificity induction for the release of DA, but also was able to monitor the release quantitatively in real time. These results showed that positive biased potential as external stimulus was favorable for the controllable release of DA, suggesting the possible application of biased potential in controllable regulation field.

Yellow Emission Obtained by Combination of Broadband Emission and Multi-Peak Emission in Garnet Structure Na2YMg2V3O12: Dy3+ Phosphor.

The fabrication and luminescent performance of novel phosphors Na2YMg2V3O12:Dy3+ were investigated by a conventional solid-state reaction method. Under near-UV light, the Na2YMg2V3O12 host self-activated and released a broad emission band (400-700 nm, with a peak at 524 nm) ascribable to charge transfer in the (VO4)3- groups. Meanwhile, the Na2YMg2V3O12:Dy3+ phosphors emitted bright yellow light within both the broad emission band of the (VO4)3- groups and the sharp peaks of the Dy3+ ions at 490, 582, and 663 nm at a quenching concentration of 0.03 mol. The emission of the as-prepared Na2YMg2V3O12:Dy3+ phosphors remained stable at high temperatures. The obtained phosphors, commercial Y2O3:Eu3+ red phosphors, and BaMgAl10O17:Eu2+ blue phosphors were packed into a white light-emitting diode (WLED) device with a near-UV chip. The designed WLED emitted bright white light with good chromaticity coordinates (0.331, 0.361), satisfactory color rendering index (80.2), and proper correlation to a color temperature (7364 K). These results indicate the potential utility of Na2YMg2V3O12:Dy3+ phosphor as a yellow-emitting phosphor in solid-state illumination.

Analysis of factors influencing parents' willingness to accept the quadrivalent influenza vaccine for school-aged children in the Nanhai District, China.

Recently, China has attached great importance to promoting immunization, prompting the media, scholars, and public to focus on its coverage and efficacy. This study aimed to understand the factors influencing parental willingness to have their school-aged children vaccinated with quadrivalent influenza vaccines (QIVs). A cross-sectional study through face-to-face interviews was conducted between September and December 2018. Forty-four kindergartens and primary and junior high schools were randomly selected via stratified three-stage cluster sampling. Of 4,430 participants, 24.6% reported having heard of QIV and 24.2% reported having previously received information on QIV. Of these, 42.8% expressed willingness to obtain the QIV for their children. A junior college degree (adjusted odds ratio [aOR] = 1.447; 95% confidence interval [95% CI]: 1.202-1.742), higher influenza knowledge level (medium level, aOR = 1.150, 95% CI, 1.006-1.314; high level, aOR = 1.332, 95% CI, 1.045-1.697), and previous influenza information (aOR = 2.241; 95% CI, 1.604-3.130) were positively correlated with vaccination willingness. In contrast, no previous QIV-related information (aOR = 0.490; 95% CI, 0.418-0.575), no perceived susceptibility of children to influenza (aOR = 0.576; 95% CI, 0.489-0.680), fear of side effects (aOR = 0.599; 95% CI, 0.488-0.735), concern that vaccines need to be carefully administered (aOR = 0.728; 95% CI, 0.593-0.894), and mistrust of new vaccines (aOR = 0.730; 95% CI, 0.628-0.849) were pivotal barriers hindering parents from having their children vaccinated. This study provides baseline information for future immunization programs and delivery, with the ultimate goal of increasing vaccine uptake and minimizing school-wide influenza outbreaks.

Probing a Reversible Cationic Switch on a Mixed Self-Assembled Monolayer Using Scanning Electrochemical Microscopy.

Probing a switch on biomimic membrane surfaces would offer some references to the research on permeability of cytomembranes. In this work, a mixed 11-mercaptoundecanoic acid/1-undecanethiol self-assembled monolayer (MUA/UT SAM) was constructed as a model of a biomembrane. In this mixed SAM, the MUA molecules work as functional parts for the switch and the UT molecules work as diluents. The surface coverage, wetting property, and pKa of this mixed SAM all have been well-inspected. The mixed SAM exhibits excellent switchable properties for cations, which is well-monitored by scanning electrochemical microscopy. When the pH of a solution is higher than the pKa, protons would stimulate a shift of dissociation equilibrium of terminal carboxyl groups. The dissociated carboxylate ions would lead to a switch on the state of the SAM. Otherwise, the SAM shows an off state when the pH is lower than the pKa. In addition, the repeatability, applicability, and the mechanism of the switch all have been well-evaluated.

A simple fluorescent probe for sensing cysteine over homocysteine and glutathione based on PET.

A big challenge is the discrimination of sulfhydryl-containing amino acids due to their structural similarity. We designed and synthesized a simple fluorescent probe 3 for specific detection of cysteine based on photo-induced electron transfer (PET). The acrylate and BODIPY moieties in probe 3 act as a reaction site and reporter group, respectively. So the synergistic effect of the substituent groups endows probe 3 very strong green fluorescence at 525nm (λex=500nm). The cleavage reaction induced by cysteine leads to acrylate hydrolysis, and thereby triggers PET on, which effectively quench the fluorescence of 3. Probe 3 exhibited a rapid response towards cysteine over homocysteine and glutathione. Probe 3 is successfully applied for sensing and imaging cysteine in vitro or in vivo cells with low cytotoxicity.

[2,5-Bis(2,2'-bipyridyl-6-yl)-3,4-diazahexa-2,4-diene]dichloridomanganese(II): from a mononuclear compound to a three-dimensional supramolecular framework through C-H···Cl hydrogen bonds and π-π stacking interactions.

The title compound, [MnCl2(C24H20N6)], has been synthesized and characterized based on the multifunctional ligand 2,5-bis(2,2'-bipyridyl-6-yl)-3,4-diazahexa-2,4-diene (L). The Mn(II) centre is five-coordinate with an approximately square-pyramidal geometry. The L ligand acts as a tridendate chelating ligand. The mononuclear molecules are bridged into a one-dimensional chain by two C-H···Cl hydrogen bonds. These chains are assembled into a two-dimensional layer through π-π stacking interactions between adjacent uncoordinated bipyridyl groups. Furthermore, a three-dimensional supramolecular framework is attained through π-π stacking interactions between adjacent coordinated bipyridyl groups.

The effectiveness of borneol on pharmacokinetics changes of four ginsenosides in Shexiang Baoxin Pill in vivo.

Shexiang Baoxin Pill (SBP) is a traditional Chinese medicine, widely used for cardiovascular diseases in the clinic. Ginsenosides are important effective components in SBP, but their pharmacokinetic characteristics are still not known. In this paper, we studied the pharmacokinetics of ginsenoside Rb1, Rc, Re and Rg1 in SBP and investigated the effect of borneol on the pharmacokinetic characteristic of ginsenosides based on an Agilent G6410A triple quadrupole LC/MS system. Results showed that the pharmacokinetic parameters of ginsenoside Rb1, Rc, Re and Rg1 in rat plasma after oral administration of SBP are significantly different with oral administration of SBP without Borneolum Syntheticum. Plasma pharmacokinetic profiles after oral administration of ginsenoside Rb1, Rc, Re, Rg1 and co-administration with borneol at three different ratios (10:1, 1:1 and 1:10 ginsenoside vs borneol, w/w) were also determined. It was demonstrated that borneol can elevate the plasma concentration of ginsenosides after co-admininstration.

Congenital syphilis: an economic evaluation of a prevention program in China.

BACKGROUND: Until now there has been no data to show the effectiveness or benefits of screening for syphilis in gravidas in China. This study was to assess the effectiveness of a program preventing mother-to-child-transmission of syphilis and to reveal factors impacting the benefit. METHODS: A cohort of 159,017 gravidas were screened for syphilis by serologic methods and infected individuals were treated with 3 injections of 2.4 million units of benzathine penicillin in Shenzhen in 2005. The pregnancy outcomes were compared for this cost-effectiveness analysis in 2 scenarios, intervention with screening and treatment versus no intervention. RESULTS: Eight hundred twenty-seven pregnant women (0.52%) were diagnosed with syphilis and treated subsequently. Of these, 200 gestations ended in miscarriage. Four babies were diagnosed with congenital syphilis; 25 neonates with low birth weight; 1 died after birth. The total cost was $636,748. On average, every $770 identified 1 infected mother. Every $4391 prevented 1 congenital syphilis; every $5135 prevented 1 low birth weight; and every $7075 prevented 1 death. One disability adjusted life year could be saved by $215. In total the program reached a benefit to cost ratio of 21.76. Sensitivity analyses revealed that this ratio was mainly impacted by the prevalence of syphilis in pregnant women and the rate of miscarriage. CONCLUSIONS: Screening for antenatal syphilis combined with intervening during gestation is highly effective in China. Reducing the percentage of spontaneous/induced abortion would be one of the most effective methods of further increasing the benefits of this screening.