Inscription of optical waveguides in crystalline silicon by mid-infrared femtosecond laser pulses

For the first time to the authors' knowledge, optical waveguides have been inscribed in bulk crystalline silicon by ultrafast laser radiation. Femtosecond laser pulses of 40-nm spectral bandwidth, 1-kHz repetition rate, and 1.7-microJ on-target energy were applied at a mid-infrared wavelength of 2.4 microm to induce nonlinear absorption in the focal volume of the beam. By scanning the laser beam with respect to the sample, buried optical waveguides have been created that were single mode at 1550 and 1320 nm and guided light only with its polarization perpendicular to the sample's surface. Propagation losses with an upper limit of 1.2 dB/cm or less were observed throughout the optical telecommunications band.     

Selective transport of zirconium (IV) and niobium (V) from hydrochloric media through a bulk liquid membrane

The selective transport of zirconium/niobium from hydrochloric medium has been investigated through a bulk liquid membrane (BLM) using tri-n-butyl-phosphate (TBP), tri-n-octylamine and dibenzo-18-crown-6 (DBC-6) as the extractants (carriers). The Optimization studies have been carried out by scrutinizing the effect of variables such as the hydrochloric acid concentration in the feed solution, membrane type and hydrochloric acid concentration in the strip solution using the Taguchi approach. The Quantitative transport of zirconium/niobium has been observed by 30% (v/v) TBP in 1200 min from the feed composed of a 9.0 M hydrochloric acid solution of Zr(IV), Nb(V) and lanthanide cations, while the transport of other cations, which have been presented along with Zr/Nb are less than 3% during the same time. Moreover, the possible mechanism of Zr(IV)/Nb(V) ion transport through the BLM has also been discussed and the results show a consecutive, irreversible second-order reaction at the interfaces. Transfer kinetics studies show that niobium transfer process exhibits slightly faster kinetics than zirconium.     

Experimental and computational approaches to reveal the potential of Ficus deltoidea leaves extract as α-amylase inhibitor

Ficus deltoidea leaves extract are known to have good therapeutic properties such as antioxidant, anti-inflammatory and anti-diabetic. We showed that 50% ethanol-water extract of F. deltoidea leaves and its pungent compounds vitexin and isovitexin exhibited significant (p < 0.05) α-amylase inhibition with IC₅₀ (vitexin: 4.6 μM [0.02 μg/mL]; isovitexin: 0.06 μg/mL [13.8 μM] and DPPH scavenging with IC₅₀ (vitexin: 92.5 μM [0.4 μg/mL]; isovitexin: 0.5 μg/mL [115.4 μM]). Additionally, molecular docking analysis confirmed that vitexin has a higher binding affinity (-7.54 kcal/mol) towards α-amylase compared to isovitexin (?5.61 kcal/mol). On the other hand, the molecular dynamics findings showed that vitexin-α-amylase complex is more stable during the simulation of 20 ns when compared to the isovitexin-α-amylase complex. Our results suggest that vitexin is more potent and stable against α-amylase enzyme, thus it could develop as a therapeutic drug for the treatment of diabetes.     

Design,synthesis and biological evaluation of quinazolin-4(3H)-one Schiff base conjugates as potential antiamoebic agents

In an effort to develop novel antiamoebic scaffolds having better efficacy than the standard drug metronidazole (IC₅₀ = 1.80 μM) used against Entamoeba histolytica, quinazolin-4(3H)-one Schiff base conjugates were synthesized and evaluated against HM1: IMSS strain of E. histolytica. Out of the thirteen compounds (S2-S14), six compounds (S2, S3, S4, S5, S6 and S11) were found to be better inhibitors than metronidazole and showed low cytotoxicity on HeLa cells, a cervical cancer cell line. The structure of intermediate compound S1 was confirmed by crystal structure studies.     

Preparation of a novel stir bar coating based on montmorillonite doped polypyrrole/nylon-6 nanocomposite for sorptive extraction of organophosphorous pesticides in aqueous samples

In the present work, a novel nanocomposite (NC) was prepared by reinforcing montmorillonite (MMT) into polypyrrole-nylon-6 (PPy-N6) hybrid through in situ oxidative polymerisation of PPy in the MMT-N6 mixture. The prepared novel NC was deposited as a thin layer coating on the stir bar substrate by solvent exchange method. Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and energy dispersive X-ray spectroscopy were applied to characterise the prepared NCs. The prepared stir bar based on MMT/PPy/N6 NC was applied for sorptive extraction of some organophosphorous pesticides (OPPs) in river water samples with detection by gas chromatography-mass spectrometry (GC-MS). The effect of MMT doping level in the NC and also the effect of PPy hybridation with N6 on the coating extraction capability were studied. Central composite design was used to optimise and study the effects of influencing factors on the stir bar sorptive extraction efficiency such as salt content, pH, extraction time, desorption time, desorption solvent and its volume. The method optimisation step was performed using gas chromatography-flame ionisation detector, while the method validation was conducted using GC-MS. Limits of detection of the developed method are in the range of 0.05–0.3 μg L^?1 and the linear dynamic ranges are in the range of 0.3–1000 and 1–1000 μg L^?1, respectively. The intra-day precision (RSD %) of developed method with four replicates varied between 5.4 and 8.2% for distilled water spiked at 100 μg L^?1. The applicability of the developed method was examined by extraction and determination of OPP compounds in river water samples, indicating the relative recoveries in the range of 80.3–95.3%.     

An Inequality on the Coding Gain of Densest Lattice Packings in Successive Dimensions

A lower bound of the form is derived on the coding gain of the densest n-dimensional (n-D) lattice(s). The bound is obtained based on constructing an n-D lattice which consists of parallel layers. Each layer isselected as a translated version of a densest ( n-1)-D lattice.0The relative positioning of the layers is adjusted to make the coding gainas large as possible. For large values of n, the bound isimproved through tightening Ryskov's inequality on covering radius andminimum distance of a lattice.     

On Proximal Relations in Transformation Semigroups Arising from Generalized Shifts

For a finite discrete topological space $X$ with at least two elements, a nonempty set $\Gamma$, and a map $\varphi:\Gamma \to \Gamma$, $\sigma_{\varphi}:X^{\Gamma} \to X^{\Gamma}$with $\sigma_{\varphi}((x_{\alpha})_{\alpha \in \Gamma})=(x_{\varphi(\alpha)})_{\alpha \in \Gamma}$ (for $(x_{\alpha})_{\alpha \in \Gamma} \in X^{\Gamma}$) is a generalized shift. In this text for $\mathcal{S} = \{\sigma_{\varphi}:\varphi \in \Gamma^{\Gamma}\}$ and $\mathcal{H}=\{\sigma_{\varphi}:\Gamma \xrightarrow{\varphi} \Gamma$ is bijective$\}$ we study proximal relations of transformation semigroups $(\mathcal{S}, X^{\Gamma})$ and $(\mathcal{H}, X^{\Gamma})$. Regarding proximal relation we prove: $$P(\mathcal{S}, X^{\Gamma}) = \{((x_{\alpha})_{\alpha \in \Gamma},(y_{\alpha})_{\alpha \in \Gamma}) \in X^{\Gamma} \times X^{\Gamma} : \exists \beta \in \Gamma (x_{\beta} = y_{\beta})\}$$and $P(\mathcal{H}, X^{\Gamma} ) \subseteq \{((x_{\alpha})_{\alpha \in \Gamma},(y_{\alpha})_{\alpha \in \Gamma}) \in X^{\Gamma} \times X^{\Gamma} : \{\beta \in \Gamma : x_{\beta} = y_{\beta}\}$ is infinite$\}$ $\cup\{($ $x,x) : x \in \mathcal{X}\}$. Moreover, for infinite $\Gamma$, both transformation semigroups $(\mathcal{S}, X^{\Gamma})$ and $(\mathcal{H}, X^{\Gamma})$ are regionally proximal, i.e., $Q(\mathcal{S}, X^{\Gamma}) = Q(\mathcal{H}, X^{\Gamma} ) = X^{\Gamma} \times X^{\Gamma}$, also for sydetically proximal relation we have $L(\mathcal{H}, X^{\Gamma}) = \{((x_{\alpha})_{\alpha \in \Gamma},(y_{\alpha})_{\alpha \in \Gamma}) \in X^{\Gamma} \times X^{\Gamma} : \{\gamma ∈ \Gamma :$ $x_{\gamma} \neq y_{\gamma}\}$ is finite$\}$.     

Synthesis and metalation of novel fluorescent conjugated macrocycles

[reaction: see text] Large shape-persistent conjugated macrocycles with tunable pore diameters in the nanometer regime were prepared by a simple, one-pot procedure. These new self-assembled macrocycles contain rings of 48-66 covalently bonded atoms and can bind multiple metal ions, forming soluble luminescent complexes.     

On-line trace enrichment of phenolic compounds from water using a pyrrole-based polymer as the solid-phase extraction sorbent coupled with high-performance liquid chromatography

A pyrrole-based conductive polymer was prepared and applied as new sorbent for on-line solid-phase extraction (SPE) of phenol and chlorophenols from water samples. Polypyrrole (PPy) was synthesized by chemical oxidation of the monomer in non-aqueous solution. The efficiency of this polymer for extraction of phenol and chlorophenols was evaluated using 35 mg of PPy as the sorbent in an on-line SPE system coupled to reversed-phase liquid chromatography with UV detection. The mobile phase were mixture of phosphate buffer-acetonitrile and compounds were eluted by the mobile phase using a six-port switching valve. High volumes of water, up to 160 ml, could be preconcentrated without the loss of phenols, except for the more polar ones. The R.S.D. for a river water sample spiked with phenol and chlorophenols at sub-ppb level was lower than 7% (n=5) and detection limits of 15-100 and 35-150 ng l⁻¹ for tap and river water were obtained, respectively.