Fluorescence Interaction and Determination of Sulfathiazole with Trypsin

The mechanism of interaction of trypsin with the sulfathiazole was studied through using fluorescence quenching and UV-visible absorption spectra at pH 7.4. The Stern-Volmer quenching constants, binding constants, number of binding sites and the corresponding thermodynamic parameters ΔH^o, ΔS^o and ΔG^o were calculated at different temperatures. The effect of common metal ions on the constants was also discussed. The results suggest that sulfathiazole can interact strongly trypsin and that there is the formation of trypsin-sulfathiazole complex and the interaction can be explained on the basis of hydrogen bonds and van der Waals forces. The binding distance (r) between the donor (trypsin) and acceptor (sulfathiazole) was 3.52 nm based on the Förster’s non-radiative energy transfer theory. The detection and quantification limits of sulfathiazole were calculated as 2.52 and 8.40 μM in the presence of trypsin, respectively. The relative standard deviation (RSD) was 4.086 % for determinations (n?=?7) of a sulfathiazole solution with the concentration of 7.54 μM.     

Cyclohexenones Through Regioselective Addition of 1,3-Dicarbonyl Compounds to Terpenoid-Like Bischalcones

Terpenoid-like bischalcones (3 and 4) were synthesized from the reaction of α- and β-ionones and benzaldehydes in excellent yields. The Michael addition of 1,3-dicarbonyl compounds to bischalcones (3 and 4) resulted in the formation of cyclohexenones derivatives (10a–d and 14a, b) via regioselective addition of 1,3-dicarbonyls and then cyclization.     

Synthesis and Characterization of New Chalcone Derivatives from cis-Bicyclo[3.2.0]hept-2-en-6-one

A series of chalcone derivatives (3a–k) were prepared via the reaction of cis-bicyclo[3.2.0]hept-2-en-6-one (1) with the respective arylaldehydes (2a–k) and were then characterized by Fourier transform infrared (FT-IR), ¹H NMR, ¹³C NMR, and elemental analyses.     

An eigenfunction expansion of the non-selfadjoint Sturm–Liouville operator with a singular potential

In this paper, we consider the operator $L$ L generated in $L^{2}\left( \mathbb{R }_{+}\right) $ L 2 R + by the differential expression $$\begin{aligned} l\left( y\right) =-y^{\prime \prime }+\left[ \frac{\nu ^{2}-\frac{1}{4}}{x^{2}}+q\left( x\right) \right] y,\,\,x\in \mathbb{R }_{+}:=\left( 0,\infty \right) \end{aligned}$$ l y = - y ' ' + ν 2 - 1 4 x 2 + q x y , x ∈ R + : = 0 , ∞ and the boundary condition $$\begin{aligned} \underset{x\rightarrow 0}{\lim }x^{-\nu -\frac{1}{2}}y\left( x\right) =1, \end{aligned}$$ lim x → 0 x - ν - 1 2 y x = 1 , where $q$ q is a complex valued function and $\nu $ ν is a complex number with $Re\nu >0$ R e ν > 0 . We have proved a spectral expansion of L in terms of the principal functions under the condition $$\begin{aligned} \underset{x\in \mathbb{R }_{+}}{Sup}\left\{ e^{\epsilon \sqrt{x}}\left| q(x)\right| \right\} <\infty , \epsilon >0 \end{aligned}$$ S u p x ∈ R + e ? x q ( x ) < ∞ , ? > 0 taking into account the spectral singularities. We have also investigated the convergence of the spectral expansion.     

A Comparison of Four Different Electrode Matrices on the Performance of Amperometric Hydrogen Peroxide (Bio)Sensors

A comparison of the analytical performances of four different (bio)sensor designs in H₂O₂ determination is discussed. The (bio)sensor designs developed were based on the use of (i) multiwalled carbon nanotubes (MWCNT), zinc oxide nanoparticles (ZnONP), prussian blue (PB); (ii) MWCNT, ZnONP, PB and ionic liquid (IL); (iii) MWCNT, ZnONP and horseradish peroxidase (HRP) and (iv) MWCNT, ZnONP, HRP and IL modified glassy carbon electrode (GCE). A performance comparison of (bio)sensors showed that the one based on HRP/IL-MWCNT-ZnONP/GCE showed the best analytical characteristics with a linear dynamic range of 9.99×10⁻⁸–7.55×10⁻⁴ M, detection limit of 1.37×10⁻⁸ M and sensitivity of 17.00 μA mM⁻¹.     

The exploring microstructural,caloric, and corrosion behavior of NiTiNb shape-memory alloys

Journal of Thermal Analysis and Calorimetry - The influence of four different quantities of niobium (Nb) on some physical and chemical properties of Ni-Ti alloy was examined in this study....     

Dynamics of quantum dot nuclear spin polarization controlled by a single electron

We present measurements of the buildup and decay of nuclear spin polarization in a single semiconductor quantum dot. Our experiment shows that we polarize the nuclei in a few milliseconds, while their decay dynamics depends drastically on external parameters. We show that a single electron can very efficiently depolarize nuclear spins in milliseconds whereas in the absence of the electron the nuclear spin lifetime is on the scale of seconds. This lifetime is further enhanced by 1-2 orders of magnitude by quenching the nonsecular nuclear dipole-dipole interactions with a magnetic field of 1 mT.     

Two-dimensional agnor evaluation as a prognostic variable in urinary bladder carcinoma: a different approach via total agnor area/nucleus area per cell

Traditional criterions are not sufficient to predict accurately the recurrence of transitional cell carcinoma of the urinary bladder. Therefore, we aimed to evaluate the AgNORs via total AgNOR area/nucleus area (TAA/NA) for each cell as a prognostic parameter, in TCC of urinary bladder. Tumor tissues of 20 consecutive cases of male bladder cancer patients were divided into two groups as middle differentiated (LG) and high grade (HG). The extra-tumoral tissue (ETT) samples of 10 males served as control group. A second control group (HC) consisted of five healthy and normal bladder tissue samples. The 3 microm of sections from each paraffin embedded tumoral, extra-tumoral and normal tissue samples served as patient and control groups. After deparaffinization and rehydratation steps, silver (AgNO(3)) staining of nucleolar organizer regions-associated proteins (AgNORs) was performed. Instead of Giemsa stain, we used Hematoxylin for contra staining. The images of the 100 analyzable nuclei from each tissue sample, transferred by means of a video camera and video capture card from microscope and recorded onto a computer. Software was prepared in Delphi language for analysis. Mean (E+02) TAA/NA values of HC, ETT, LG and HG groups were 6.97+2.80, 5.70+1.82, 7.80+3.22 and 9.24+3.88, respectively. Statistical comparisons have shown significant differences between all groups.In conclusion, mean TAA/NA per cell has a potential to be a prognostic parameter. Therefore, further evaluation of big patient series will be useful.     

Oxygen bridged Homobinuclear Mn(II) compounds with Anthranilic acid: Theoretical calculations,oxidation and catalase activity

Two new homobinuclear manganese compounds with mixed ligands, [Mn₂(μ_1,1–2‐NH₂C₆H₄COO)₂(phen)₄](ClO₄)2(CH₃OH) ( 1 ), and [Mn₂(μ_1,3–2‐NH₂C₆H₄COO)₂(bipy)₄](ClO₄)2 ( 2 ) (NH₂C₆H₄COOH = anthranilic acid, bipy = 2,2′‐bipyridine, phen = 1,10‐ phenanthroline) were synthesized and thoroughly characterized by elemental analysis, IR, UV and single crystal X‐ray crystallography. X‐ray structure analysis shows that in the mono‐ and bidentate carboxylate bridged compounds, Mn–Mn distances of 1 and 2 are 3,461 Å, and 4,639 Å, respectively. The energy of the compounds was determined with a DFT (Density Functional Theory) calculation on B3LYP/6‐31G(d,p) optimized geometry by using the B3LYP/6‐31G(d,p) basis set. These compounds acts as biomimetic catalyst and show catalase‐like activity for the hydrogen peroxide dismutation at room temperature in different solvents with remarkable activity (TOF, Turnover frequency = mol of subst./(mol of cat. × time)) up to 12640 h^?1 with 1 , and 17910 h^?1 with 2 in Tris–HCl buffer). Moreover, the catalytic activity of 1 and 2 has been studied for oxidation of alcohols (cinnamyl alcohol, benzyl alcohol, cyclohexanol, 1‐octanol and 1‐heptanol) and alkenes (cyclohexene, styrene, ethyl benzene, 1‐octene and 1‐hexene) in a homogeneous catalytic system consisting t‐butylhydroperoxide (TBHP) as an oxidant in acetonitrile. Both compounds exhibited very high activity in the oxidation of cyclohexene to cyclohexanone (~80% selectivity, ~99% conversion in 1 h, TOF = 243 h^?1 and 226 h^?1) and cinnamyl alcohol to cinnamaldehyde (~64% selectivity) as the main product with very high TOF value (9180 h^?1 and 13040 h^?1 in the first minute of reaction) (~100% conversion in 0.5 h) with TBHP at 70 °C in acetonitrile, for 1 and 2 , respectively.     

Online Solid-Phase Extraction of Cd(II), Cu(II), and Co(II) Using Covalently Attached Bis(salicylaldimine) to Silica Gel for Determination in Food and Water by Flame Atomic Absorption Spectrometry

In this study, a novel sorbent material bearing a bis(aldimine) group was designed and successfully synthesized by covalently bonding a 2-[N,N′-bis(salicylaldimine)]aminoethyl amine ligand to the silica gel surface that was characterized by carbon, hydrogen, and nitrogen elemental analysis, thermogravimetric analysis, and the Fourier transform infrared spectroscopy technique. The sorbent was used for the online solid-phase extraction (SPE) of Cd(II), Cu(II), and Co(II) ions for their determination at trace concentration levels by flame atomic absorption spectrometry. The effective factors for the online SPE such as the pH and the flow rate of the sample solution, and type, volume, and flow rate of eluent were investigated. The concentration levels of Cd(II), Cu(II), and Co(II) were measured in certified reference materials including Virginia tobacco leaves (CTA-VTL-2) and water-trace elements (NWTM-15.2) to validate this method. The metal levels in environmental water were determined by this method, and the values were checked by spiking and recovery experiments and independent analysis by inductively coupled plasma-mass spectrometry. The adsorption capacities of the sorbent were found to be 41.2, 31.6, and 25.6?mg/g for Cd(II), Cu(II), and Co(II), respectively. This method was also successfully used for the determination of Cd(II), Cu(II), and Co(II) concentrations in rice and molasses.