Analysis of the CO2 and NH3 reaction in an aqueous solution by 2D IR COS: formation of bicarbonate and carbamate

The two-dimensional (2D) infrared correlation spectra obtained from the reaction time- and concentration-dependent IR spectra elucidates the reaction of CO2 and NH3 in an aqueous solution for CO2 absorption. In the synchronous 2D correlation spectra, the interrelation of the proton with carbamate and bicarbonate indicates that the pH level affected the formation reactions of the two products. Furthermore, the interrelation of carbamate with bicarbonate confirmed the conversion of carbamate into bicarbonate with the release of protons (or the decrease of the pH). From the experimental results including the asynchronous 2D correlation spectra, the reaction of the CO2 and aqueous ammonia proceeded through the following steps: formation of carbamate, formation of bicarbonate, release of protons, and conversion of carbamate into bicarbonate. The analysis of the formation of carbamate and bicarbonate by 2D infrared correlation spectroscopy provides useful information on the reaction mechanism of CO2 and NH3 in aqueous solutions.     

Spectroscopic observation of atomic hydrogen radicals entrapped in icy hydrogen hydrate

A hydrogen molecule entrapped in the cages of icy hydrogen hydrate is confined in host water framework and thus behaves unlike pure solid or liquid hydrogen. The gamma-irradiated hydrogen radicals are for the first time observed from ESR and solid-state MAS 1H NMR spectra to stably exist in the icy hydrate channels without any collapse of the host framework, confirming the chemical shift consistency of ionized hydrogen derivatives. We discuss the confined icy hydrate channels, which can act as potential storage sites for simultaneously imprisoning both molecular and ionized hydrogen and further as icy nanoreactors.     

Temperature-dependent 3-D CuI coordination polymers of calix[4]-bis-dithiacrown: crystal-to-crystal transformation and photoluminescence change on coordinated solvent removal

The temperature-dependent assembly of two 3-D CuI coordination polymers containing calix[4]-bis-thiacrown with different networking motifs are reported. Upon removal of the coordinated solvent molecules the initial solvent-coordinated polymer undergoes a unique single-crystal-to-single-crystal transformation to the desolvated polymer. Structural characteristics observed in the solvent-coordinated and the desolvated polymers also reveal related solvato-photolunimescence "off-on" behavior.     

Quantification of doxazosin in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

Hydrophilic interaction LC with MS/MS (HILIC-MS/MS) was described as a rapid, sensitive, and selective method for the quantification of doxazosin in human plasma. Doxazosin and cisapride (internal standard) were extracted from human plasma with ethyl acetate at alkaline pH and analyzed on an Atlantis HILIC Silica column with the mobile phase of ACN/ammonium formate (100 mM, pH 4.5) (93:7 v/v). The analytes were detected using an ESI MS/MS in the selective-reaction-monitoring mode. The standard curve was linear (r = 0.9994) over the concentration range of 0.2-50 ng/mL. The LOQ for doxazosin was 0.2 ng/mL using 100 microL plasma sample. The CV and relative error for intra- and interassay at four QC levels were 3.7-8.7% and 0.0-9.8%, respectively. The matrix effect for doxazosin and cisapride were practically absent. The recoveries of doxazosin and cisapride were 67.4 and 61.7%, respectively. This method was successfully applied to the pharmacokinetic study of doxazosin in humans.     

Photochemical stability of nonlinear optical chromophores in polymeric and crystalline materials

We compare the photochemical stability of the nonlinear optical chromophore configurationally locked polyene 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) embedded in a polymeric matrix and in a single-crystalline configuration. The results show that, under resonant light excitations, the polymeric compound degrades through an indirect process, while the DAT2 crystal follows a slow direct process. We show that chromophores in a crystalline environment exhibit three orders of magnitude better photostability as compared to guest-host polymer composites.     

Optimal classification for time-course gene expression data using functional data analysis

Classification problems have received considerable attention in biological and medical applications. In particular, classification methods combining to microarray technology play an important role in diagnosing and predicting disease, such as cancer, in medical research. Primary objective in classification is to build an optimal classifier based on the training sample in order to predict unknown class in the test sample. In this paper, we propose a unified approach for optimal gene classification with conjunction with functional principal component analysis (FPCA) in functional data analysis (FNDA) framework to classify time-course gene expression profiles based on information from the patterns. To derive an optimal classifier in FNDA, we also propose to find optimal number of bases in the smoothing step and functional principal components in FPCA using a cross-validation technique, and compare the performance of some popular classification techniques in the proposed setting. We illustrate the propose method with a simulation study and a real world data analysis.     

Quencher-free molecular beacons: a new strategy in fluorescence based nucleic acid analysis

Molecular beacons (MBs) have been used as viable fluorescent probes in nucleic acid analysis. Many researchers around the world continue to modify the MBs to suit their needs. As a result, a number of nucleic acid probing systems with close resemblance to the MBs are being reported from time to time. Quencher-free molecular beacons (QF-MBs) are a significant modification of the conventional MB; in QF-MBs the quencher part has been eliminated. Despite the absence of the quencher, the QF-MBs can identify specific target DNA. They can also be used in SNP typing and in real-time PCR analysis for quantification of DNAs. The design, factors behind functioning and applications of different types of QF-MBs and closely related quencher-free nucleic acid probing systems (QF-NAPs) have been described in this tutorial review.     

A new 3D nickel(II) framework composed of large rings: Ionothermal synthesis and crystal structure

Ionothermal reaction between Ni²⁺ and 1,3,5-benzentricarboxylic acid (H₃BTC) with [AMI]Cl (AMI=1-amyl-3-methylimidazolium) as the reaction medium produced a novel 3D mixed-ligand metal-organic framework [AMI][Ni₃(BTC)₂(OAc)(MI)₃] (1) (MI=1-methylimidazole) with [AMI]⁺ incorporated in the framework. The framework is formed by connecting 2D planes, made up of 32- and 48-membered rings, through 1D chains composed of 32-membered rings. The two BTC³⁻ ligands in 1 show the same connectivity mode with two bidentate and one μ₂ bridging carboxylic groups. This is a new connectivity mode to the already existing 17 in the Ni-BTC system. The role of MI and [AMI]Cl in the structure formation is discussed.     

A solid-phase synthetic method for 3,4-dihydro-1H-2,1-benzothiazin-4-one 2,2-dioxide derivatives

Utilizing polymer-bound anthranilic acid derivatives, we were able to obtain 3,4-dihydro-1H-2,1-benzothiazine-4-one 2,2-dioxide derivatives through N-methanesulfonylation by use of sulfonyl chloride, sulfonic acid, or sodium sulfonate, N-alkylation under Mitsunobu condition, and the cyclative cleavage in 8-52% five-step overall isolated yields and 91-99% purities from Wang resin. The reactions on solid phase were monitored by on-bead ATR-FTIR spectroscopic method and checked by help of solution-phase model experiments.     

Paramagnetic gold nanostructures for dual modal bioimaging and phototherapy of cancer cells

Paramagnetic gold nanostructures were synthesized by combining the paramagnetism of gadolinium with the plasmonic properties of gold nanoparticles and used for dual modal (MRI and optical) imaging and phototherapy of breast cancer cells.