Direct DNA Hybridization on the Single‐Walled Carbon Nanotubes Modified Sensors Detected by Voltammetry and Electrochemical Impedance Spectroscopy

Carboxylic acid functionalized single‐walled carbon nanotubes modified graphite sensors (SWCNT‐PGEs) were developed for electrochemical monitoring of direct DNA hybridization related to specific sequence of Hepatitis B virus, which substantially enhance the electrochemical transduction resulting from guanine oxidation signal comparison to bare PGEs. The performance characteristics of DNA hybridization on disposable CNT‐PGE were explored measuring the guanine signal in terms of optimum analytical conditions; probe and target concentration, hybridization time, and selectivity. The voltammetric results were also complemented with electrochemical impedance spectroscopy (EIS), that was used to characterize the successful construction of carbon nanotubes modification onto the surface of PGEs.     

Phenylethyl Glycosides from Digitalis lanata

Three new phenylethyl glycosides, 3′′′′‐O‐methylmaxoside (=2‐(3,4‐dihydroxyphenyl)ethyl O‐β‐D ‐glucopyranosyl‐(1→3)‐O‐[β‐D ‐glucopyranosyl‐(1→6)]‐4‐O‐(E)‐feruloyl‐β‐D ‐glucopyranoside; 1 ), digilanatosides A (=2‐(3,4‐dihydroxyphenyl)ethyl O‐6‐O‐(E)‐sinapoyl‐β‐D ‐glucopyranosyl‐(1→3)‐4‐O‐(E)‐caffeoyl‐β‐D ‐glucopyranoside; 2 ), and digilanatoside B (=2‐(3,4‐dihydroxyphenyl)ethyl O‐6‐O‐(E)‐p‐coumaroyl‐β‐D ‐glucopyranosyl‐(1→3)‐4‐O‐(E)‐caffeoyl‐β‐D ‐glucopyranoside; 3 ) were isolated from the aerial parts of Digitalis lanata, along with two known phenylethyl glycosides, purpureaside A and maxoside, a phenylpropanoid glucose ester, 1‐O‐(E)‐feruloyl‐β‐glucopyranose, a benzoquinolethanoid glucoside, cornoside, a cardenolide, lanatoside C, a furostane‐type steroidal saponin, purpureagitoside, and a disaccharide, sucrose. Their structures were elucidated on the basis of spectroscopic evidence (1D‐ and 2D‐NMR, and HR‐MALDI‐MS).     

1H magnetic resonance spectroscopy of the normal testis: preliminary findings

PURPOSE: The purpose of this study was to determine the pre- and postpubertal 1H magnetic resonance spectroscopic characteristics of the normal testis to establish baseline values for further clinical studies. MATERIALS AND METHODS: The subjects consisted of male volunteers, of whom 19 were prepubertal with ages between 7 and 13 years and 24 were postpubertal with ages between 19 and 39 years. Their testes were evaluated at 1.5 T with magnetic resonance spectroscopy; in addition, testis volumes were measured. Major metabolite peaks were identified and their ratios were calculated. Metabolite differences of testis between pre- and postpubertal age were analyzed. RESULTS: Major constituents of spectra were 3.21 ppm choline and 0.9-1.3 ppm lipid peaks. At the echo time (TE) spectrum of 31 ms, choline/lipid ratios ranged from 0.35 to 8.30 (mean=1.87) in postpubertal males and from 0.06 to 5.45 (mean=0.88) in prepubertal males (P<.013). At the TE spectrum of 136 ms, choline/lipid ratios ranged from 0.66 to 15.42 (mean=4.09) in postpubertal males and from 0.05 to 4.91 (mean=0.9) in prepubertal males (P<.016). CONCLUSIONS: Choline/lipid ratio was higher in the postpubertal period. The existence of higher choline peak in that age group should be due to the initiation of spermatogenesis. The decrease in the lipid peak may represent the effect of testosterone on testicular tissue or may be due to histochemical changes initiated by puberty. The significant decrease in choline/lipid ratio noted after puberty could represent the presence of spermatogenesis. This hypothesis should be evaluated by further studies on postpubertal subjects with impaired spermatogenesis.     

Orthogonal Nanoparticle Catalysis with Organogermanes

Although nanoparticles are widely used as catalysts, little is known about their potential ability to trigger privileged transformations as compared to homogeneous molecular or bulk heterogeneous catalysts. We herein demonstrate (and rationalize) that nanoparticles display orthogonal reactivity to molecular catalysts in the cross‐coupling of aryl halides with aryl germanes. While the aryl germanes are unreactive in L_nPd⁰/L_nPd^II catalysis and allow selective functionalization of established coupling partners in their presence, they display superior reactivity under Pd nanoparticle conditions, outcompeting established coupling partners (such as ArBPin and ArBMIDA) and allowing air‐tolerant, base‐free, and orthogonal access to valuable and challenging biaryl motifs. As opposed to the notoriously unstable polyfluoroaryl‐ and 2‐pyridylboronic acids, the corresponding germanes are highly stable and readily coupled. Our mechanistic and computational studies provide unambiguous support of nanoparticle catalysis and suggest that owing to the electron richness of aryl germanes, they preferentially react by electrophilic aromatic substitution, and in turn are preferentially activated by the more electrophilic nanoparticles.     

Are middle school mathematics teachers able to solve word problems without using variable?

Many people consider problem solving as a complex process in which variables such as x,?y are used. Problems may not be solved by only using ‘variable.’ Problem solving can be rationalized and made easier using practical strategies. When especially the development of children at younger ages is considered, it is obvious that mathematics teachers should solve problems through concrete processes. In this context, middle school mathematics teachers' skills to solve word problems without using variables were examined in the current study. Through the case study method, this study was conducted with 60 middle school mathematics teachers who have different professional experiences in five provinces in Turkey. A test consisting of five open-ended word problems was used as the data collection tool. The content analysis technique was used to analyze the data. As a result of the analysis, it was seen that the most of the teachers used trial-and-error strategy or area model as the solution strategy. On the other hand, the teachers who solved the problems using variables such as x, a, n or symbols such as Δ, □, ○, * and who also felt into error by considering these solutions as without variable were also seen in the study.     

Dissipative photonic lattice solitons

We show that discrete dissipative optical lattice solitons are possible in waveguide array configurations that involve periodically patterned semiconductor optical amplifiers and saturable absorbers. The characteristics of these low-power soliton states are investigated, and their propagation constant eigenvalues are mapped on Floquet-Bloch band diagrams. The prospect of observing such low-power dissipative lattice solitons is discussed in detail.     

Photo and Thermo‐luminescence Properties of Mn4+, Ce4+ and Sm3+ in MgAl2Si2O8 Phosphor

Mn⁴⁺, Ce⁴⁺ and Sm³⁺ doped MgAl₂Si₂O₈‐based phosphors were synthesized at 1300 °C by solid state reaction and characterized by thermogravimetry (TG), differential thermal analysis (DTA), X‐ray powder diffraction (XRD), photoluminescence (PL), thermoluminescence (TL) and scanning electron microscopy (SEM). The phosphors showed broad red emission bands in the range of 610–715 nm and different maximum intensity when activated by UV illumination. Such a red emission can be attributed to the intrinsic ²E→⁴A₂ transitions of Mn⁴⁺.     

Allele-specific genotyping by using guanine and gold electrochemical oxidation signals

Electrochemical DNA biosensors have become strong candidates for DNA based analysis. Allele-specific genotyping is also one of the important research areas, where electrochemical approaches provide promising advances. Recently reported two methods based on electrochemical guanine and colloidal gold (Au) nanoparticle oxidation signals are reviewed and compared with the existing genotyping methods in this report.