From cyclic polyenes to carbohydrates: synthesis of the hexose sugar β-allose and its 2C-branched homologue from cyclooctatetraene

In an unconventional but interesting synthetic enterprise, the commercially available hydrocarbon cyclooctatetraene (COT) has been elaborated to the rare hexose sugar (dl)-β-allose and its 2C-branched analogue. The synthetic sequence delineated here is notable for its high regio- and stereoselectivity and is flexible enough to enable access to polyoxygenated systems, hexose sugars, and their siblings from a cyclic polyene precursor.     

Effect of O5+ ion implantation on the electrical and structural properties of Cu nanowires

Ion beam creates changes in the material along their track, not only embody the excellent properties but also tailor new materials. When the ions are implanted into the nanomaterials, they collide with the target atoms and interact through three different phenomena; electron collision, nuclear collision and charge exchange. In the present study, 1 MeV O⁵⁺ ions were implanted in copper nanowires of diameter 80 nm synthesized using template synthesis approach. Electrical and structural properties were recorded using Keithley 2400 series source meter and Rigaku X-ray diffractometer respectively, before and after the implantation. I–V characteristics showed the ohmic behavior with enhancement in conductivity of copper nanowires after implantation. No structural damage in the nanowires was revealed by XRD spectra. The work done can be viewed as a positive aspect of implantation in metallic nanowires especially in 80 nm diameter Cu nanowires and may be utilized to fabricate nanodevices.     

Molecular Engineering Approaches Towards All-Organic White Light Emitting Materials

White light emitting (WLE) materials are of increasing interest owing to their promising applications in artificial lighting, display devices, molecular sensors, and switches. In this context, organic WLE materials cater to the interest of the scientific community owing to their promising features like color purity, long-term stability, solution processability, cost-effectiveness, and low toxicity. The typical method for the generation of white light is to combine three primary (red, green, and blue) or the two complementary (e.g., yellow and blue or red and cyan) emissive units covering the whole visible spectral window (400–800 nm). The judicious choice of molecular building blocks and connecting them through either strong covalent bonds or assembling through weak noncovalent interactions are the key to achieve enhanced emission spanning the entire visible region. In the present review article, molecular engineering approaches for the development of all-organic WLE materials are analyzed in view of different photophysical processes like fluorescence resonance energy transfer (FRET), excited-state intramolecular proton transfer (ESIPT), charge transfer (CT), monomer-excimer emission, triplet-state harvesting, etc. The key aspect of tuning the molecular fluorescence under the influence of pH, heat, and host–guest interactions is also discussed. The white light emission obtained from small organic molecules to supramolecular assemblies is presented, including polymers, micelles, and also employing covalent organic frameworks. The state-of-the-art knowledge in the field of organic WLE materials, challenges, and future scope are delineated.     

Selective removal of anomeric O-acetate groups in carbohydrates using HClO4-SiO2

A convenient methodology has been developed for the selective removal of the anomeric acyl group of carbohydrate derivatives using HClO₄-SiO₂ under acidic reaction conditions. Anomeric benzoyl groups can also be removed selectively following similar reaction conditions. The yields were excellent in all cases.     

Functional outlier detection with robust functional principal component analysis

Functional principal component analysis is the preliminary step to represent the data in a lower dimensional space and to capture the main modes of variability of the data by means of small number of components which are linear combinations of original variables. Sensitivity of the variance and the covariance functions to irregular observations make this method vulnerable to outliers and may not capture the variation of the regular observations. In this study, we propose a robust functional principal component analysis to find the linear combinations of the original variables that contain most of the information, even if there are outliers and to flag functional outliers. We demonstrate the performance of the proposed method on an extensive simulation study and two datasets from chemometrics and environment.     

A Direct Approach to Insulin Isotherm Analysis in Reversed Phase Chromatography

There is a need to demonstrate the application of a simple isotherm method and a process chromatography optimization methodology with its approximations and assumptions that is useful when quick application is required. This paper presents an explanation of a basic procedure for the optimization of the acetonitrile concentration under isocratic condition with insulin as the model compound, using the retention time method for single component isotherm measurement. The retention time method was used to measure the adsorption isotherm over the concentration range of 26–29% acetonitrile. The assumption of a single component isotherm for insulin is appropriate in this study since the shift of the peak front due to a tag-along effect of the des-amido insulin degradation product is minimal. This RTM method assumes a Langmuir isotherm model. This model is an accurate representation under these experimental conditions as revealed by the shape of the measured shock front time as a function of amount loaded. Analysis of the isotherm results shows the ‘a’ parameter decreases with increasing volume per cent acetonitrile and the column saturation capacity decreases with increasing volume per cent acetonitrile. The cycle time is represented by ‘a’ parameter and the loading factor by the column saturation capacity. Since the ‘a’ parameter increases with decreasing volume per cent acetonitrile, the cycle time increases and the production rate decreases. On the other hand, the column saturation capacity increases with decreasing volume per cent acetonitrile; therefore, the optimum loading factor increases, thus the production rate increases. This trade-off leads to an optimum acetonitrile concentration at low k′ until practical operational limits are achieved.     

A combinatorial analog of a theorem of F.J. Dyson

Tucker's lemma is a combinatorial analog of the Borsuk–Ulam theorem and the case $n=2$ was proposed by Tucker in 1945. Numerous generalizations and applications of the lemma have appeared since then. In 2006 Meunier proved the lemma in its full generality in his PhD thesis. There are generalizations and extensions of the Borsuk–Ulam theorem that do not yet have combinatorial analogs. In this note, we give a combinatorial analog of a result of Freeman J. Dyson and show that our result is equivalent to Dyson's theorem. As with Tucker's lemma, we hope that this will lead to generalizations and applications and ultimately a combinatorial analog of Yang's theorem of which both Borsuk–Ulam and Dyson are special cases.     

In vitro and in vivo photodynamic activity of core-modified porphyrin IY69 using 690 nm diode laser

Core-modified porphyrins have been explored as the second-generation photosensitizers due to their excellent photophysical properties. IY69 [(5-phenyl-10,15-bis(4-carboxylatomethoxyphenyl)-20-(2-thienyl)-21,23-dithiaporphyrin] was developed from the structure optimization guided by in vitro phototoxicity, showing potent activity (IC(50)=80 nm, broadband at 5 J cm(-2), R3230AC cells). The present study demonstrates in vivo photodynamic therapy (PDT) efficacy of IY69 using a murine tumor model (colon 26 cells on BALB/c mice) and 690 nm diode laser. In vitro phototoxicity of IY69 with the diode laser was compared with that with broadband light against colon 26 cells. Attenuation of the laser light by tissue samples was determined to estimate actual power density at targets. Biodistribution in various organs 24, 48, 72 h after i.p. administration was determined. Even though IY69 phototoxicity with the diode laser was less effective than that with the broadband light, the diode laser was quite effective in vitro (IC(50)=0.1 μm, 10 J cm(-2), colon 26 cells). Concentration and light dose-dependent phototoxicity was observed. A significant light attenuation of 95% and 99% was observed by skin and 3 mm muscle with skin. IY69 PDT showed significant damage on tumor and delay in tumor growth in a dose-dependent manner.