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The analysis of the states of gas accumulated at the liquid/solid interface on the basis of the continuum theory in which the Hamaker constant is used to describe the long-range interaction at the microscopic scale is reported.

The study was conducted to demonstrate the utility of (ion-pair reversed phase) IR-RP-capillary for heparan sulfate (HS) oligasaccharide. The studies concluded that solution parameters have opposite effect on the performance of ion-pair reversed phase high performance liquid chromatography (IR-RP-HPLC) and negative ion ESI-Ms.

The organic-organic self-assembly of the triblock copolymer and resols leads to the formation of several ordered cubic mesoporous carbon single-crystals with perfect rhombdodecahedral morphology. The results show that such an approach, apart from providing specification of crystal growth and mesistrcuture, also helps to meet the demand of emerging nanodevice technologies.

The synthesis of highly ordered mesoporous carbons and silicas with ultralarge accessible pores is conducted. Results reveal that the mesoporous carbons (denoted as C-FDU-18) possess face centered cubic closed-packing (fcc) mesostructure with large-domain ordering.

A simple DNA-sensing platform is developed on the basis of the fluorescence resonance energy transfer (FRET) between blue-luminescent CdTe quantum dots (QDs) and dye-labeled single-stranded DNA (ssDNA). The differential interaction of single-stranded and double-stranded DNA with Cd[Te.sup.+) results in differential changes of FRET efficiency, which is used to recognize the hybridization event.

The mass-analyzed threshold ionization spectra of jet-cooled cis- and trans-3-fluoro-N-methylaniline (3FNMA) were recorded by ionizing via the vibrationless 00 and various vibrational levels of the S1 state. The adiabatic ionization energies of cis- and trans-3FNMA are determined to be 61 742 ± 5 and 61 602 ± 5 cm-1, respectively. In the 0-1800 cm-1 region, most of the observed vibrations in the D0 state result from the in-plane ring deformation and substituent-sensitive modes. For the high-frequency vibration region, the infrared-ultraviolet double-resonance and autoionization-detected infrared spectroscopies were applied to investigate the N-H and C-H stretching vibrations of bare 3FNMA in the S0 and D0 states. The C-H stretching vibrational information, which we failed to obtain for the bare 3FNMA cation, is complemented by recording the infrared-photodissociation spectra of its Ar cluster cation. It is revealed that a red-shifted frequency and an enhanced intensity are observed for the N-H stretch, while blue-shifted frequencies and greatly decreased intensities are found for both aromatic and the methyl C-H stretches. The blue shift of the C-H stretches is first explained by the balance of two factors, namely, the hyperconjugative interaction and the rehybridization effect. Analysis of the vibrational frequencies reveals a correlation between the relative stability of two rotamers in different electronic states and the relative rigidity of aromatic ring, indicating a mechanism of the long-range interactions "through bond" between the substituents. The density functional theory calculations can well reproduce the vibrational spectra in both S0 and D0 states. With the experimental and theoretical data, the substitution and conformation effects on the properties of 3FNMA in the S0 and D0 states, including the molecular structures, the reactive sites of electrophilic attack, and the vibrational behaviors, were discussed in detail. [ABSTRACT FROM AUTHOR]

Oxygen vacancies can control a number of distinct properties of oxides. However, rapid and simple detection of oxygen vacancies is a great challenge owing to their elusive species and highly diluted contents. In this work, we have discovered that cataluminescence (CTL) intensity in diethyl ether oxidation reaction on the surface of TiO2 nanoparticles is proportional to the content of oxygen vacancies. The oxygen vacancy-dependent diethyl ether CTL is attributed to the fact that abundant chemisorbed O2 in oxygen vacancies could facilitate its contact reaction with chemisorbed diethyl ether molecules, resulting in an obvious improvement of CTL intensity. Therefore, diethyl ether CTL can be employed as a simple probe for oxygen vacancies in TiO2 nanoparticles. Its feasibility is validated by detecting the CTL intensity of diethyl ether on the surface of TiO2 with variable oxygen vacancies by metal ion-doped TiO2 nanoparticles (Cu, Fe, Co, and Cr) and hydrogen-treated TiO2 nanoparticles at different temperatures. The content of oxygen vacancies by the present CTL probe is in good agreement with that obtained by conventional X-ray photoelectron spectroscopy (XPS) technique. The superior properties of the developed CTL probe over already-developed methods include fast response, easy operation, low cost, long-term stability, and simple configuration. We believe that the oxygen vacancy-sensitive CTL probe has a great potential in distinguishing oxygen vacancies in oxides. [ABSTRACT FROM AUTHOR]

The emergence of aggregation-induced emission (AIE) has opened up a new avenue for scientists. There is a great demand for the development of a new generation chemiluminescence resonance energy transfer (CRET) acceptors with AIE characteristics due to the aggregation-caused chemiluminescence (CL) quenching effect commonly observed in the conventional fluorophore CL acceptors at high concentrations. However, the systematical studies involving in AIE-amplified CL are still scarce. Herein, it is the first report that the gold nanocluster aggregates (a type of well-defined AIE molecules) are used to study their influence on the bis(2,4,6-trichlorophenyl) oxalate (TCPO)–H2O2 CL reaction. Interestingly, the AIE molecules in the diluted solution are unable to boost the CL signal of the TCPO–H2O2 system, but their aggregates display a strongly enhanced CL emission compared to their counterparts of fluorophore molecules, thanks to the unique AIE effect of gold nanoclusters. In comparison to rhodamine B with the aid of an imidazole catalyst, the detection limit of the gold nanocluster aggregate-amplified CL probe for H2O2 (S/N = 3) is low in the absence of any catalyst. Finally, the other two typical AIE molecules, Au(I)-thiolate complexes and 9,10-bis[4-(3-sulfonatopropoxyl)-styryl]anthracene (BSPSA), are investigated to verify the generality of the AIE molecule-amplified CL emissions. These results demonstrate effective access to highly fluorescent AIE molecules with practical applications in avoiding the aggregation-induced CL quenching at high concentrations, which can be expected to provide a novel and sensitive platform for the CL amplified detection. [ABSTRACT FROM AUTHOR]

Rapid and effective evaluation techniques for heterogeneous base catalysts in biodiesel production are highly desirable with increased global demand for biofuels. In this work, we have discovered direct connections between the number of medium-strength basic sites of heterogeneous base catalysts in biodiesel production and cataluminescence intensity in acetone aldol condensation reactions. Accordingly, acetone cataluminescence has been employed as an indicator for rapid evaluation of heterogeneous base catalysts in biodiesel production. Its practical feasibility has been first established using commercially available heterogeneous base catalysts in biodiesel production (including MgO, Al2O3, TiO2, and ZnO), indicating a good matching between the proposed cataluminescence screening method and routine temperature-programmed desorption measurements. subsequently, the proposed cataluminescence method can be used to effectively distinguish a set of layered double hydroxides and layered double oxide with fewer differences of basic sites, and the relative standard deviation (RSD) of the proposed method is 2.90%. The developed cataluminescence platform is able to take advantage of low cost, simple configuration, fast response, long-term stability, and easy operation. This work has a great potential in distinguishing weak/strong basic sites and even acidic sites of each catalyst system by tuning molecular probes. [ABSTRACT FROM AUTHOR]

C-termini of proteins often play an important role in various biological processes. The determination of the protein C-terminus is crucial because it provides not only distinct functional annotation but also a way to monitor the proteolysis-modified proteins. In this study, an isotopic labeling approach based on oxazolone chemistry was developed to achieve the identification and quantification of C-termini. Aminolysis reagents such as arginine selectively react with the a-carboxyl group at the peptide C-terminus via an oxazolone-like intermediate. Side chain carboxyl groups do not participate in this reaction. When an isotopic mixture consisting of 50% arginine (0Arg) and 50% C6-arginine (6Arg) was introduced to react with C-terminus of protein and followed by proteolysis, the C-terminal peptide could be directly recognized in the mass spectrum due to its unique isotopic paired peaks, and the sequence could be interpreted in MS2. Besides, the incorporation of an additional basic amino acid in the C-terminal peptide greatly enhanced the signal intensity for C-termini detection. Moreover, the isotopic arginine labeling strategy could be applied for relative C-termini quantitation. Our method showed an excellent correlation of the measured ratios to theoretical ratios and high reproducibility within 2 orders of magnitude of the dynamic range. The correlation coefficients (R2) were higher than 0.99, with the coefficients of variation (CVs) ranging from 1.16 to 10.91%. Finally, the approach was used to analyze the C-termini from Thermoanaerobacter tengcongensis, which was cultured under different temperatures. As a result, 68 C-termini have been identified, and 53 of them were quantified in total using our strategy. In addition, 24 neo-C-terminal peptides have also been discovered. [ABSTRACT FROM AUTHOR]