Phonon fingerprints of CsPb2Br5.

CsPb2Br5 is a stable, water-resistant, material derived from CsPbBr3 perovskite and featuring two-dimensional Pb-Br framework separated by Cs layers. Both compounds can coexist at nanolength scale, which often produces conflicting optical spectroscopy results. We present a complete set of polarized Raman spectra of nonluminescent CsPb2Br5 single crystals that reveals the symmetry and frequency of nondegenerate Raman active phonons accessible from the basal (0 0 1) plane. The experimental results are in good agreement with density functional perturbation theory simulations, which suggests that the calculated frequencies of yet unobserved double degenerate Raman and infrared phonons are also reliable. Unlike CsPbBr3, the lattice dynamics of CsPb2Br5 is stable as evidenced by the calculated phonon dispersion. The sharp Raman lines and lack of a dynamic-disorder-induced central peak in the spectra at room temperature indicate that the coupling of Cs anharmonic motion to Br atoms, known to cause the dynamic disorder in CsPbBr3, is absent in CsPb2Br5.

[Effects of pneumoperitoneal pressure on air embolism duringlaparoscopic hepatectomy and degree of postoperative inflammation].

Objective: To investigate the incidence and severity of embolicevents, and degree of postoperative inflammation when pneumoperitoneal pressures 15 mmHg and 12 mmHg were used during laparoscopic hepatectomy. Methods: A computer-generated 1∶1 randomization protocol was used to assign fifty patients to either the 15 mmHg(P15, n=25) or 12 mmHg(P12, n=25) group. Throughout the surgery, air embolisms were detected by transesophageal echocardiography (TEE) and graded based on their size. Vital signs, arterial blood gases (ABG), P(ET)CO(2) levels, blood loss, operative time and postoperative hospital stays were monitored. 2 ml blood samples were taken before and after operation finished 0, 12 and 24 h by using EDTA anticoagulated tubes in order to detect the IL-6, TNF-α and IL-10 level in plasma. Results: CO(2) embolism occurred in 100% of the enrolled patients. The frequencies of severe air embolism were 76%(n=19) in P15 group and 52% (n=13) in P12 group, respectively. The duration of severe embolism episodes in P15 group was much longer than that in P12 group[(58.0±22.6) s vs(36.6±17.8)s, t=3.71, P<0.01]. The incidence of complications in group P15 was 24%, which was higher than that in group P12 of 4%(χ(2)=4.15, P<0.05). The postoperative pro-inflammatory cytokine IL-6 and TNF-α in group P15 at the point of 12 hour after operation[685.66(435.18-935.52)ng/L, 31.00(18.29-41.15)ng/L]were statistically higher than those in group P12 [480.50(255.28-685.34) ng/L, 21.00(14.87-31.64) ng/L, P<0.05], whereas the anti-inflammatory cytokine IL-10 in P15 group[18.00(5.75-30.55) ng/L]was statistically lower than the P12 group [26.89(15.03-38.00) ng/L, P<0.05]. There was no statistical difference in operative time, blood loss and postoperative hospital stay between the two groups. Conclusion: The higher pneumoperitoneal pressure during laparoscopic hepatectomy causes more serious gas embolism, prolongs embolic duration and lead to more sever inflammatory response.

Measurement of resilience in Chinese older people.

BACKGROUND: Resilience has been identified as a personal construct that may contribute to the process of healthy ageing in older people. To date, no measurement instrument has been tested to evaluate resilience in Chinese older people. AIM: To examine the psychometric testing and clinical application of the Chinese version of the Resilience Scale (RS) in Chinese older people. METHODS: A descriptive cross-sectional study design was used. Forward and backward translation procedures were used to obtain semantic equivalence of the original English version of the RS. Content validity was examined by identified experts, followed by exploratory factor analysis, item-to-total correlation, Cronbach's α coefficients and test-retest reliability. RESULTS: The 25-item Chinese version of Resilience Scale (RS-CN) was fully completed by 461 Chinese older people. Cronbach's α for the total Chinese version of the Revised Resilience Scale was 0.95, with a range of 0.85-0.89 for the sub-scales. Item-to-total correlation coefficients ranged from 0.51 to 0.75 and items were excluded with item-to-total correlations coefficients lower than 0.4. The test-retest reliability of the total scale was 0.80, sub-scale test-retest reliability ranged from 0.61 to 0.620. The exploratory principal component analysis with varimax rotation revealed RS-CN to have a four-factor structure. CONCLUSION: The RS-CN is a valid and reliable instrument for the measurement of the concept of resilience in Chinese older people. The results of this study provide cross-cultural evidence for the potential application of this scale in Chinese older people. IMPLICATIONS FOR NURSING AND HEALTH POLICY: Greater insight into the psychological constructs of resilience in Chinese older people can lead to international comparisons and to the potential development of interventions for this population around the world.

High-resolution fiber optic temperature sensors using nonlinear spectral curve fitting technique.

A generic new data processing method is developed to accurately calculate the absolute optical path difference of a low-finesse Fabry-Perot cavity from its broadband interference fringes. The method combines Fast Fourier Transformation with nonlinear curve fitting of the entire spectrum. Modular functions of LabVIEW are employed for fast implementation of the data processing algorithm. The advantages of this technique are demonstrated through high performance fiber optic temperature sensors consisting of an infrared superluminescent diode and an infrared spectrometer. A high resolution of 0.01 °C is achieved over a large dynamic range from room temperature to 800 °C, limited only by the silica fiber used for the sensor.

Epitaxial Catalyst-Free Growth of InN Nanorods on c-Plane Sapphire.

We report observation of catalyst-free hydride vapor phase epitaxy growth of InN nanorods. Characterization of the nanorods with transmission electron microscopy, and X-ray diffraction show that the nanorods are stoichiometric 2H-InN single crystals growing in the [0001] orientation. The InN rods are uniform, showing very little variation in both diameter and length. Surprisingly, the rods show clear epitaxial relations with the c-plane sapphire substrate, despite about 29% of lattice mismatch. Comparing catalyst-free with Ni-catalyzed growth, the only difference observed is in the density of nucleation sites, suggesting that Ni does not work like the typical vapor-liquid-solid catalyst, but rather functions as a nucleation promoter by catalyzing the decomposition of ammonia. No conclusive photoluminescence was observed from single nanorods, while integrating over a large area showed weak wide emissions centered at 0.78 and at 1.9 eV.

Ultrafast dynamic control of spin and charge density oscillations in a GaAs quantum well.

We use subpicosecond laser pulses to generate and monitor in real time collective oscillations of electrons in a modulation-doped GaAs quantum well. The observed frequencies match those of intersubband spin- and charge-density excitations. Light couples to coherent density fluctuations through resonant stimulated Raman scattering. Because the spin- and charge-related modes obey different selection rules and resonant behavior, the amplitudes of the corresponding oscillations can be independently controlled by using shaped pulses of the proper polarization.

Identification and biochemical characterization of a novel nortriterpene inhibitor of the human lymphocyte voltage-gated potassium channel, Kv1.3.

A novel nortriterpene, termed correolide, purified from the tree Spachea correae, inhibits Kv1.3, a Shaker-type delayed rectifier potassium channel present in human T lymphocytes. Correolide inhibits 86Rb+ efflux through Kv1.3 channels expressed in CHO cells (IC50 86 nM; Hill coefficient 1) and displays a defined structure-activity relationship. Potency in this assay increases with preincubation time and with time after channel opening. Correolide displays marked selectivity against numerous receptors and voltage- and ligand-gated ion channels. Although correolide is most potent as a Kv1.3 inhibitor, it blocks all other members of the Kv1 family with 4-14-fold lower potency. C20-29-[3H]dihydrocorreolide (diTC) was prepared and shown to bind in a specific, saturable, and reversible fashion (Kd = 11 nM) to a single class of sites in membranes prepared from CHO/Kv1.3 cells. The molecular pharmacology and stoichiometry of this binding reaction suggest that one diTC site is present per Kv1.3 channel tetramer. This site is allosterically coupled to peptide and potassium binding sites in the pore of the channel. DiTC binding to human brain synaptic membranes identifies channels composed of other Kv1 family members. Correolide depolarizes human T cells to the same extent as peptidyl inhibitors of Kv1.3, suggesting that it is a candidate for development as an immunosuppressant. Correolide is the first potent, small molecule inhibitor of Kv1 series channels to be identified from a natural product source and will be useful as a probe for studying potassium channel structure and the physiological role of such channels in target tissues of interest.