Improvement of in vitro digestibility and thermostability of debranched waxy maize starch by sequential ethanol fractionation.

This study aimed to improve the in vitro digestibility and thermostability of debranched waxy maize starch (DWMS) by sequential fractionation. Waxy maize starch was debranched by pullulanase, followed by sequential precipitation through controlling the ratio of starch supernatants to ethanol at 1:0.5, 1:1, and 1:1.5 (v/v). Subsequently the structural, thermal, in vitro digestive properties of DWMS were investigated. In vitro digestion results showed that the secondary ethanol fractionation of 1:1 on the basis of the initial fractionation (1:0.5) induced a significant higher amount of slowly digestive starch (SDS, 30.0 %) and resistant starch (RS, 58.6 %) amongst all three fractions, along with the highest peak temperature (Tp, 106.4 °C) and the highest decomposition value (Td, 310.0 °C) in calorimetric (DSC) and thermogravimetry (TGA) measurements. Chain length distribution, surface morphology, and laser confocal micro-Raman spectroscopy (LCM-Raman) analyses revealed that medium (degree of polymerization, DP 13- 36) and long chains (DP ≥37) respectively constituting 72.0 % and 10.2 % of DWMS resulted in the formation of spheroidal crystallites with higher homogeneity and more ordered short-range structures. Overall, this work confirmed that ethanol fractionation is an efficient method for improving the in vitro digestibility and heat stability of waxy maize starch.

Size effect on nonlinear optical properties and ultrafast dynamics of silver nanoparticles.

Z-scan technology was used to study the nonlinear absorption (NLA) and nonlinear refraction (NLR) of silver nanoparticles (Ag NPs) with various sizes under different laser intensities. The results demonstrate that the NLA and NLR of Ag NPs were size-dependent. Specifically, the 10 nm Ag NPs exhibit saturation absorption (SA) and insignificant NLR. The 20 and 40 nm Ag NPs show the coexistence of SA and reverse saturation absorption (RSA). SA is believed to result from ground-state plasma bleaching, whereas RSA originates from excited state absorption (ESA). The 20 nm and 40 nm Ag NPs shows increasing self-defocusing with the increase of laser intensity. It was observed that the energy relaxation of Ag NPs mainly includes two processes of electron-phonon and phonon-phonon couplings on the order of picoseconds.

Nonlinear optical properties of InP/ZnS core-shell quantum dots.

The nonlinear optical properties of an InP/ZnS core-shell quantum dot toluene solution were investigated using a Z-scan and transient absorption technique with femtosecond pulses and nanosecond pulses at 532 nm wavelengths, respectively. The research results showed that InP/ZnS core-shell quantum dots exhibited saturated absorption under the excitation of femtosecond pulses, and the switch from saturated absorption to reverse saturated absorption was observed under the excitation of nanosecond pulses. The mechanism of the switch was attributed to excited-state absorption. Moreover, the nonlinear refraction was shown as self-focusing and self-defocusing under the excitation of femtosecond and nanosecond pulses, respectively, which were attributed to the Kerr effect of electrons and the thermal effect of InP/ZnS quantum dots, respectively. The investigations show that InP/ZnS core-shell quantum dots are good materials, and have many potential applications in optical and electrical fields.

Wavelength-dependent nonlinear absorption and ultrafast dynamics process of Au triangular nanoprisms.

The nonlinear absorption and ultrafast dynamics process of Au triangular nanoprisms were investigated by using broadband (ranging from 550 to 700 nm) nanosecond Z-scan measurements and femtosecond time-resolved transient absorption spectrum, respectively. We found that Au triangular nanoprisms exhibit saturation absorption (SA) at low excitation intensities. With the increase of incident intensity, a switch from SA to reverse saturation absorption (RSA) occurs. Photo-dynamics process was found to be a double-exponential energy relaxation with a fast and a slow decay component. Interestingly, when probe wavelength is away from the plasma resonance peak, the decay of relaxation also shows the modulation due to the vibration mode of the coherent excitation.

Ultrafast spectroscopic studies of composition-dependent near-infrared-emitting alloyed CdSeTe quantum dots.

In this study, optical and structural characterizations of near-infrared-emitting alloyed CdSeTe quantum dots (QDs) are measured after the dissolution in toluene. Luminescence spectra are obtained from alloyed CdSeTe QDs under 800 nm femtosecond laser excitation. With increasing pump fluence, the line width or full width at half maximum (FWHM) of photoluminescence (PL) spectrum becomes larger than 10 nm due to increasing temperature. Ultrafast spectroscopic properties of CdSeTe QDs are investigated by means of time-resolved PL, transient absorption (TA) and Z scan techniques. Moreover, open-aperture (OA) Z scan measurement is used to clarify the composition and pump fluence dependence of optical nonlinearity under femtosecond laser excitation. With increasing pump fluence, evolution from saturable absorption to reverse saturable absorption in CdSeTe QDs is observed. The transition process is analyzed via a phenomenological model based on nonlinear absorption coefficient and saturation intensity, which indicates that CdSeTe QDs have potential for applications in all-optical switching devices.

Ultrafast optical properties of type-II CdZnS/ZnSe core-shell quantum dots.

In this study, the ultrafast optical properties of type-II CdZnS/ZnSe core-shell quantum dots were investigated using the Z-scan and transient absorption technique with femtosecond pulses. With 800-nm wavelength excitation, the CdZnS/ZnSe quantum dots exhibited two-photon absorption, and the two-photon absorption cross section was obtained as about 3.37 × 106 GM. In addition, the transfer time of electrons and the recombination lifetime of a single exciton were obtained. For the photoluminescence of the CdZnS/ZnSe quantum dots at temperatures from 80 to 280 K, the peak position redshifted by 60 meV, width broadened by 3 meV, and intensity decreased by a factor of four.

Combination of exendin-4 and DPP-4 silencing promoted angiogenesis of human coronary artery endothelial cells via activation of PI3K/Akt pathway.

This study was aimed to explore the combined effects of Exendin-4 with dipeptidyl peptidase-IV (DPP-4) silencing on vascular endothelial growth factor (VEGF)-induced cell proliferation and angiogenesis in Human Coronary Artery Endothelial Cells (HCAECs), as well as the underlying molecular mechanisms which were involved in this process. HCAECs were treated by exendin-4, small interfering RNA (siRNA) targeting DPP-4 (DPP-4-siRNA) or exendin-4 plus DPP-4-siRNA, respectively. Cell migration, proliferation and angiogenesis in vitro were assessed by scratch-wound assay, MTT, tran swell assay, and matrigel tube formation, respectively. Cell apoptosis was investigated by TUNEL assay. Expression of apoptosis and PI3K/Akt related proteins were assessed by Western blotting. Incubation of HCAECs with exendin-4 and silencing of DPP-4 both caused an increase in cell proliferation, migration and tube formation, while a significant decrease in apoptosis (all p<0.05). Furthermore, the combination of the exendin-4 and silencing of DPP-4 had additional effects on HCAECs. Protein levels of p-Akt and p-PI3K were markedly increased by exendin-4 incubation, silencing of DPP-4 in HCAECs. These results suggest that combination of exendin-4 and silencing of DPP-4 had additional promoted effects on angiogenesis of HCAECs via activation of PI3K/Akt pathway. Our study indicated an alternative therapeutic strategy for atherosclerotic neovascularization.

Quasi-type II CuInS2/CdS core/shell quantum dots.

Ternary chalcopyrite CuInS2 quantum dots (QDs) have been extensively studied in recent years as an alternative to conventional QDs for solar energy conversion applications. However, compared with the well-established photophysics in prototypical CdSe QDs, much less is known about the excited properties of CuInS2 QDs. In this work, using ultrafast spectroscopy, we showed that both conduction band (CB) edge electrons and copper vacancy (VCu) localized holes were susceptible to surface trappings in CuInS2 QDs. These trap states could be effectively passivated by forming quasi-type II CuInS2/CdS core/shell QDs, leading to a single-exciton (with electrons delocalized among CuInS2/CdS CB and holes localized in VCu) half lifetime of as long as 450 ns. Because of reduced electron-hole overlap in quasi-type II QDs, Auger recombination of multiple excitons was also suppressed and the bi-exciton lifetime was prolonged to 42 ps in CuInS2/CdS QDs from 10 ps in CuInS2 QDs. These demonstrated advantages, including passivated trap states, long single and multiple exciton lifetimes, suggest that quasi-type II CuInS2/CdS QDs are promising materials for photovoltaic and photocatalytic applications.

Ultrafast Interfacial Electron and Hole Transfer from CsPbBr3 Perovskite Quantum Dots.

Recently reported colloidal lead halide perovskite quantum dots (QDs) with tunable photoluminescence (PL) wavelengths covering the whole visible spectrum and exceptionally high PL quantum yields (QYs, 50-90%) constitute a new family of functional materials with potential applications in light-harvesting and -emitting devices. By transient absorption spectroscopy, we show that the high PL QYs (∼79%) can be attributed to negligible electron or hole trapping pathways in CsPbBr3 QDs: ∼94% of lowest excitonic states decayed with a single-exponential time constant of 4.5 ± 0.2 ns. Furthermore, excitons in CsPbBr3 QDs can be efficiently dissociated in the presence of electron or hole acceptors. The half-lives of electron transfer (ET) to benzoquinone and subsequent charge recombination are 65 ± 5 ps and 2.6 ± 0.4 ns, respectively. The half-lives for hole transfer (HT) to phenothiazine and the subsequent charge recombination are 49 ± 6 ps and 1.0 ± 0.2 ns, respectively. The lack of electron and hole traps and fast interfacial ET and HT rates are key properties that may enable the development of efficient lead halide perovskite QDs-based light-harvesting and -emitting devices.

Anxiety disorders are associated with increased plasma adrenomedullin level and left ventricular hypertrophy in patients with hypertension.

OBJECTIVE: To investigate the association between anxiety disorders and left ventricular hypertrophy in patients with essential hypertension. METHODS: Left ventricular structure and function were assessed with echocardiography in 56 patients with essential hypertension and anxiety disorder (study group) and in 56 patients with hypertension only (control group). Serum adrenomedullin levels were also measured in these patients. RESULTS: There was no statistically significant difference in the left ventricular ejection fraction between the study and the control group (54.21 ± 88.81% versus 56.01 ± 7.85%, p>0.05). The left ventricular mass index (LVMI) in study group was higher than in control group (137.05 ± 9.42 versus 123.57 ± 7.01 g/m(2), p=0.001). The plasma levels of adrenomedullin in study group was higher than in control group (25.97 ± 5.48 versus 18.32 ± 6.97 ng/L, p=0.001). Levels of plasma adrenomedullin were positively correlated with LVMI in the study (r=0.734, p<0.05) and control group (r=0.592, p<0.05). CONCLUSION: Anxiety disorders are associated with elevated plasma adrenomedullin levels and increased left ventricular hypertrophy in patients with essential hypertension. The clinical significance of these changes requires further investigation.

Comparison of oral and intravenous hydration strategies for the prevention of contrast-induced nephropathy in patients undergoing coronary angiography or angioplasty: a randomized clinical trial.

OBJECTIVE: The efficacy of oral hydration in the prevention of contrast-induced nephropathy in patients undergoing elective coronary intervention is unclear. METHODS: A total of 120 patients were randomly assigned to three groups. Group A (n = 40) received intravenous hydration before and after coronary angiography or angioplasty. Group B (n = 40) received oral tap water before and after the procedures, whereas group C (n = 40) received only postprocedural drinking water. Levels of serum creatinine and urea nitrogen were measured before, 12 hours after, 2 and 3 days after the coronary angiography or angioplasty. RESULTS: : There was no statistically significant difference in the age, sex, baseline renal function and the volume of contrast medium used during the coronary procedures among the three groups (P > 0.05).There was no statistically significant difference in the mean serum creatinine or urea nitrogen among the three groups 12 hours, and 3 days after the coronary procedures ( P > 0.05).The incidence of contrast-induced nephropathy in group A, B and C was 5.0% (2/40), 7.5% (3/40) and 5.0% (2/40), respectively (P = 0.86). Renal function in the seven patients who experienced contrast-induced nephropathy recovered within a week following rehydration treatment. CONCLUSIONS: Pre- and post-procedural oral hydration was as effective as intravenous rehydration in the prevention of contrast-induced nephropathy in patients undergoing coronary angiography or angioplasty.

Plasma nitric oxide and left ventricular function in rabbits after cardiac lymphatic obstruction.

This study was designed to investigate the effect of cardiac lymphatic obstruction on plasma nitric oxide (NO) and left ventricular function. The plasma NO was measured in study group (n = 21) and control group rabbits (n = 12) before, and 3, 7, 14, 30 and 90 days after the obstruction of cardiac lymphatic vessels. Left ventricular ejection fraction was measured with echocardiography. There was a significant reduction in the left ventricular ejection fraction following the lymphatic obstruction (0.72±0.02 vs. 0.61±0.02, p<0.01). Plasma NO in the control group remained unchanged during the observation period (54.2±4.4 vs. 52.0±4.2 µmol/L, p>0.05). In the study group, there was a small but significant increase in the plasma NO on day 3, 7 and 14 following the lymphatic obstruction (52.3±4.1 vs. 73.4±5.9 µmol/L, p<0.01). The plasma NO returned to the baseline levels on day 30 but reduced to 44.9±3.6 µmol/L on 90 days after the lymphatic obstruction (p<0.05). In conclusion, cardiac lymphatic obstruction was associated with a significant reduction in left ventricular function. It was also associated with an increase in the plasma NO in the first 2 weeks but there was a significant reduction in the NO levels three months after the lymphatic obstruction.

Ultrafast third-order nonlinear optical properties of ZnPc(OBu)(6)(NCS)/DMSO solution.

The ultrafast third-order nonlinear optical properties of ZnPc(OBu)(6)(NCS)/dimethyl sulfoxide solution are investigated by optical Kerr effect (OKE) and pump-probe techniques with femtosecond pulses. Using CS(2) as the reference, the third-order susceptibility of the sample solution is obtained as about 1.40x10(-14) esu at a concentration of 3.00x10(-5) M. The second hyperpolarizability for the sample solution is deduced to be as large as 2.35x10(-31) esu. The dynamic characteristics of the nonlinear optical response and the origins of the OKE signal can be attributed to excited singlet state populations.

Generalized anxiety disorder and the circadian rhythm of blood pressure in patients with hypertension.

Objective. To investigate the impact of generalized anxiety disorder (GAD) on the circadian rhythm of blood pressure in patients with hypertension. Methods. The 24-h ambulatory blood pressure was compared between patients with hypertension and GAD, and patients with hypertension only. Results. The mean day- and night-time systolic (SBP, 156.6±11.0 and 149.6±12.4 mmHg, respectively) blood pressure in patients with GAD was greater than in the no-GAD group (143.2±15.0 and 126.0±10.8 mmHg, respectively, P<0.01). The mean day- and night-time diastolic blood pressure (DBP, 101.5±10.1 and 96.9±17.6 mmHg, respectively) in the GAD group was also greater than in the no-GAD group (94.1±10.9 and 77.4±10.2 mmHg, respectively, P<0.01). SBP and DBP dipping was found in 87.5 and 80.1% of the hypertension only patients, as compared with 16.6 and 21.4% respectively, of the hypertension and GAD patients (P<0.01). Conclusions. The presence of GAD is associated with a higher level of blood pressure in hypertensive patients. GAD is also associated with a diminished circadian rhythm of blood pressure. The clinical significance of the reduced blood pressure dipping at night requires further investigation.