Five methods for detection of Helicobacter pylori in the Turkish population

AIM: To compare culture analysis, Helicobacter pylori (H. pylori) stool antigen (HpSA) test, polymerase chain reaction (PCR) and fluorescence in situ hybridization (FISH) for H. pylori detection. METHODS: One hundred and thirty-two consecutive adult dyspeptic patients receiving diagnostic endoscopy at the department of gastroenterology were enrolled in this study. Culture and histological examination were performed on biopsy specimens. PCR and FISH tests were applied to histopathological samples. Stool samples that were simultaneously collected were tested for the H. pylori antigen using the HpSA test and bacterial DNA using stool PCR. RESULTS: H. pylori was positively identified by histo-logical examination in 85/132 (64.4%) of the patients, while positive samples were found in 56 (42.4%), 64 (48.5%), 98 (74.2%), 28 (21.2%) and 81 (61.4%) of the patients by culture, HpSA, PCR, stool PCR and FISH methods, respectively. The results of the culture, biopsy PCR, HpSA and FISH tests, with the exception of the stool PCR, were found to correlate with the histological examination as a gold standard. CONCLUSION: The HpSA test is a rapid, simple, and noninvasive test for monitoring therapy. FISH is an accurate, rapid, cost-effective, and easy-to-use test for H. pylori detection.

Enhancement of Frster energy transfer from thermally activated delayed fluorophores layer to ultrathin phosphor layer for high color stability in non-doped hybrid white organic light-emitting devices

Fluorescence/phosphorescence hybrid white organic light-emitting devices（WOLEDs） based on double emitting layers（EMLs） with high color stability are fabricated.The simplified EMLs consist of a non-doped blue thermally activated delayed fluorescence（TADF） layer using 9,9-dimethyl-9,10-dihydroacridine-diphenylsulfone（DMAC-DPS） and an ultrathin non-doped yellow phosphorescence layer employing bis[2-（4-tertbutylphenyl）benzothiazolato-N,C2＇]iridium（acetylacetonate）（（tbt）_2Ir（acac））.Two kinds of materials of 4,7-diphenyl-1,10-phenanthroline（Bphen） and 1,3,5-tris（2-Nphenylbenzimidazolyl） benzene（TPBi） are selected as the electron transporting layer（ETL）,and the thickness of yellow EML is adjusted to optimize device performance.The device based on a 0.3-nm-thick yellow EML and Bphen exhibits high color stability with a slight Commission International de l＇Eclairage（CIE） coordinates variation of（0.017,0.009） at a luminance ranging from 52 cd/m^2 to 6998 cd/m^2.The TPBi-based device yields a high efficiency with a maximum external quantum efficiency（EQE）,current efficiency,and power efficiency of 10%,21.1 cd/A,and 21.3 lm/W,respectively.The ultrathin yellow EML suppresses hole trapping and short-radius Dexter energy transfer,so that Forster energy transfer（FRET）from DMAC-DPS to（tbt）_2Ir（acac） is dominant,which is beneficial to keep the color stable.The employment of TPBi with higher triplet excited state effectively alleviates the triplet exciton quenching by ETL to improve device efficiency.

Improved Method for Determination of Raspberry Ketone in Fragrance Mist by HPLC-Fluorescence Analysis after Pre-Column Derivatization with 4-(<i>N,N</i>-Dimethylaminosulfonyl)-7-(<i>N</i>-chloroformylmethyl-<i>N</i>-methylamino)-2,1,3-benzoxadiazole

Raspberry ketone {RK, 4-(4-hydroxyphenyl)butan-2-one} is structurally resembles 4-(4-hydroxyphenyl)-2-butanol, which causes leukoderma on consumers’ skin. Therefore, it is important to measure in cosmetics for quality assessment. Very recently, an HPLC-fluorescence method for determination of RK in a fragrance mist by pre-column derivatization with 4-hydrazino-7-nitro-2,1,3-benzoxadiazole hydrazine was established. However, the derivatization conditions (80&deg;C, 20 min) were severe. In this study, an improved pre-column derivatization with 4-(N,N-dimethylaminosulfonyl)-7-(N-chloro-formylmethyl-N-methylamino)-2,1,3-benzoxadiazole (DBD-COCl) is presented by HPLC-fluorescence method for determination of RK. The DBD-CO-RK derivative was eluted from a reversed-phase ODS column, and detected with excitation at 440 nm and emission at 543 nm. Derivatization was performed at room temperature for 3 min. The retention time of DBD-CO-RK derivative was 16.8 min. The standard curve was linear in the range of 0.05 to 2.5 μg/mL, with a correlation coefficient (r2) value of 0.9988. The lower limit of detection was 0.01 μg/mL (absolute amount of 0.3 pmol). The coefficients of variation were less than 10.0%. The content of RK in fragrance mist (1.00 mL) was 1.20 ± 0.08 mg (range, 1.10 to 1.31 mg, n = 5). Recovery tests were satisfactory (91.8 ± 5.4%;range, 84.2 to 98.2%, n = 5).

A Neglected Issue in Testing Particles in the Solution

The particles are one of the most promising materials in the 21st century,and have become one of the research hotspots in many disciplines111.In the process of application or characterization,it is usually necessary to disperse the particles(the particle size is commonly less than 1 pm)in the solvent121.It is generally believed that the particles in the solution are uniformly distributed after simple handling,such as ultrasonication,shaking,or pipetting131.If the density of particles is different from that of the solvent,the particles in the solution will sink(assuming Boltzmann distribution according to the most probable macroscopic state of statistical thermodynamics)due to the influence of the gravNational potential field(Fig.l).