Lifting Triplet Energy and Bipolar Characteristics by Limiting the Rotation of the Peripheral Groups in Host Materials to Achieve High-Efficiency Blue OLED.

Bipolar host materials with high triplet energy are of great significance for highly efficient blue organic light-emitting diodes (OLEDs). In this work, three donor-acceptor-donor (D-A-D) type host materials with identical non-rigid diphenylsulfone center but differing in rotation degree of peripheral amino substituted derivatives from rotating freely diphenylamine (SODP) to rotating partially iminodibenzyl (SOId) and rotating restricted carbazole (SOCz) were designed and synthesized. It was demonstrated that the triplet energy (ET ) level of the materials promoted by limiting the rotation degree of the peripheral groups, which was 2.72 eV for SODP, 2.73 eV for SOId and 2.78 eV for SOCz, respectively. Besides, the results of the single-carrier devices indicate SOCz possess better bipolar characteristic. Using FIrpic as guest emitter, the blue OLED with SOCz as host material exhibited superior device performance with a low turn-on voltage of 3.3 V, a maximum current efficiency (CE) of 30.1 cd A-1 , a maximum power efficiency (PE) of 32.2 lm W-1 , and a maximum external quantum efficiency (EQE) of 14.0%. This work provides a beneficial guideline for realizing promising host materials in efficient blue OLEDs.

Thermal effect of holmium laser during ureteroscopic lithotripsy.

BACKGROUND: Holmium laser lithotripsy is the most common technique for the management of ureteral stone. Studies founded that holmium laser firing can produce heat which will cause thermal injury towards ureter. The aim of our current study is to explore factors affecting thermal effect of holmium laser during ureteroscopic lithotripsy. METHODS: An in vitro experimental model is design to simulate the ureteroscopic lithotripsy procedure. Different laser power settings (10w (0.5JX20Hz, 1.0 JX10Hz), 20w (1.0 JX20Hz, 2.0 JX10Hz), 30w (1.5JX20Hz, 3.0 JX10Hz)) with various firing time (3 s, 5 s, 10s) and irrigation flow rates(10 ml/min, 15 ml/min, 20 ml/min and 30 ml/min) were employed in the experiment. The temperature around the laser tip was recorded by thermometer. RESULTS: The temperature in the "ureter" rises significantly with the increasing laser power, prolonging firing time and reducing irrigation flow. The highest regional temperature is 78.0 °C at the experimental set-up, and the lowest temperature is 23.5 °C. Higher frequency setting produces more heat at the same power. Laser power < =10w, irrigation flow> = 30 ml/min and "high-energy with low-frequency" can permit a safe working temperature. CONCLUSION: We clarify that the thermal effect of holmium laser is related with both laser working parameters and irrigation flow. The proper setting is the key factor to ensure the safety during ureteroscopic holmium laser lithotripsy.

Regeneration of tetrabutylammonium ion-pairing reagent distribution in a gradient elution of reversed phase ion-pair chromatography.

The regeneration of ion-pairing reagent distribution on liquid chromatography columns after gradient elution has been well recognized as the cause for long column equilibration time, a major drawback associated with gradient elution reverse phase ion-pair chromatography. To date, the majority of studies have focused on optimizing the separation conditions to shorten the equilibration time. There is limited understanding of the ion-pairing reagent distribution process between the mobile phase and stationary phase in the course of gradient elution, and subsequent column re-equilibration. The focus of this work is to gain a better understanding of this process. An ion-pair chromatographic system, equipped with a YMC ODS C(18) column and a mobile phase containing tetrabutylammonium (TBA) hydroxide as the ion-pairing reagent, was used in the study. The TBA distribution profile was established by measuring its concentration in the eluent fractions collected during the gradient cycle using different column equilibration times with an ion chromatographic method. Furthermore, the analyte retention time was evaluated as the function of the column equilibration time and TBA concentration in the mobile phase. The column equilibration and its impact on the method robustness will also be discussed.

[Relation between level of expression of high mobility group protein B1 in hepatic tissue with the severity and prognosis of sepsis in rat].

OBJECTIVE: To investigate whether the levels of expression of high mobility group protein B1 (HMGB1) in hepatic tissue are related with severity and prognosis of sepsis in rat, in order to look for a dependable marker for monitoring and evaluating the efficiency of the treatment of sepsis. METHODS: Ninety SD rats (specific-pathogen free, male, 250-300 g) were randomly divided into sham operation group (group A), cecal ligation and puncture (CLP) group (group B) and CLP followed by ethyl pyruvate (EP) treatment group (group C). Laparo fury was done aseptically, and the cecum was returned to the abdomen (group A) or CLP was carried out (group B and C). The abdominal wall was then closed layer by layer. Normal saline (NS) 2 ml (group A and B) or EP 2 ml (130 mg/kg, group C) was intraperitoneally injected and repeated every 12 hours. Five animals were sacrificed at 0, 6, 12, 24, 48 and 72 hours after the operation, blood samples and 100 grams of hepatic tissue were harvested before the animal died. Before sacrifice, activity, food taking, piloerection, diarrhea, anophthalmia, respiration, distention of intestine, hyperemia, ascites, and omental adhesion to the cecum, and hyperemia of lung were observed. Another group of 20 rats were used to observe the survival rate after CLP. The level of HMGB1 mRNA expression in the hepatic tissue was assessed by reverse transcriptase-polymerase chain reaction (RT-PCR), and the levels of interleukin-1 beta (IL-1 beta), IL-6 and tumor necrosis factor-alpha (TNF-alpha) in plasma were determined by enzyme linked immunoadsorbent assay (ELISA). RESULTS: The mortality of sepsis was higher in group B than other groups (both P<0.01), that of group C was significantly lower than B but higher than A (both P<0.01). The levels of IL-1 beta, IL-6 and TNF-alpha in plasma rose to the peak at 6 hours after CLP in all groups, and group B>group C>group A (P<0.01), and they descended at 12 hours. The HMGB1 mRNA expression level in hepatic tissue was measurable at 6 hours and rose at 12 hours in group B, and maintained a high level up to 48 hours after CLP. The HMGB1 expression was positive correlated with IL-6 (r=0.91). The value in group C was significantly lower than group B at all time points (all P<0.01). The degree of severity and survival rate of sepsis were highly correlated with HMGB1 levels. CONCLUSION: As a late-released inflammatory mediator, HMGB1 plays a key role in lethal effect of sepsis, the surviving time and the severity degree of sepsis are highly correlated with HMGB1 expression level in hepatic tissue.