Surface plasmon resonance and field enhancement in #-shaped gold wires metamaterial

A #-shaped gold wires metamaterial is designed for surface enhanced Raman spectroscopy (SERS) and sensing. The tunability of surface plasmon resonance (SPR) excitations, hotspots distribution, localized field enhancement and sensitivity of the structure are investigated. In contrast to most metamaterial, the #-shaped structure exhibits two pronounced SPRs that are insensitive to the polarization of excitation light. Pure electromagnetic Raman enhancement factors of about 10(6) are achieved on the symmetrically distributed field hotspots. It is possible to break the usable wavelength range of conventional gold SERS substrates via higher order excitations of the #-shaped metamaterial. In addition, the sensitivity and the figure of merits are found to be comparable or even higher than those of conventional SERS substrates. All these factors together with the high reproducibility nature of metamaterial and its simple planer structure suggest that this structure is very promising for surface enhanced spectroscopy and sensing applications.

SPP-associated dual left-handed bands and field enhancement in metal-dielectric-metal metamaterial perforated by asymmetric cross hole arrays

Dual-band left-handed transmissions in the near infrared frequencies through the metal-dielectric-metal metamaterial perforated with an array of asymmetric cross holes are demonstrated. It is shown that the left-handed bands originate from the SPP-associated magnetic response excited by different polarized light and their frequencies can be tuned by the arm's length or width of the cross-gaps. The structures are further optimized at 1.064 microm laser light excitation for elucidating the mechanism and possible application in surface enhanced Raman spectroscopy in sandwiched architectures. This study provides valuable information for the design of compact optical devices with dual left-handed bands in a single structure and may also pave the way toward stable and reproducible substrate design for surface enhanced Raman spectroscopy.

Antisymmetric resonant mode and negative refraction in double-ring resonators under normal-to-plane incidence

Compared to metallic composite metamaterials of double split-ring resonators with wires, double-ring resonators without additional wires are simple to engineer. In this paper, we have numerically studied the transmittance of double split- and closed-ring resonators at normal-to-plane incidence and identified their fundamental resonance modes. It is found that the antisymmetric and symmetric resonance modes originate from the out-of-phase and in-phase oscillations of surface charges in the neighboring legs of the double-ring resonators, respectively. The coupling of the antiparallel induced currents in the neighboring legs gives rise to magnetic resonance and consequently negative permeability of the antisymmetric mode. The negative refraction transmission of the double-ring resonators at normal-to-plane incidence is verified by dispersion curve and wedge-shaped model simulations. Our study provides a route to negative refraction metamaterial design by using the antisymmetric resonance mode of the simple double-ring structure at normal-to-plane incidence which is of particular importance for the terahertz and infrared domain.

Electronic structure, bonding and phonon modes in the negative thermal expansion materials of Cd(CN)(2) and Zn(CN)(2)

The disordered configuration, band structures, density of states, Mulliken population, elastic constants, zone center optic phonon modes and their Grüneisen parameters of M(CN)(2) (M =  Cd, Zn) have been studied for possible cyanide-ordering patterns by the first-principles plane-wave pseudopotential method based on density functional theory. Total energy calculations predict that MC(2)N(2)-MC(2)N(2) is the most favorable configuration for Cd(CN)(2) whereas all three possible configurations are near equally favorable for Zn(CN)(2). Effective charges and bond order analyses reveal that the M(CN)(2) (M =  Cd, Zn) frameworks include much stiffer [Formula: see text] and weaker M-C/N bonds, which account for the flexing of the M-CN-M linkage during the transverse motion of the cyanide-bridge. The transverse translational and the librational modes give rise to negative Grüneisen parameters and therefore contribute to the negative thermal expansion. Transverse vibrations of the C and N atoms in the same (transverse translational modes) or opposite (librational modes) directions have the same effect of drawing the anchoring metal atoms closer. Among all the optical phonon modes, the lowest-energy transverse translational optical modes which are neither Raman nor infrared active in Cd(CN)(2) and Zn(CN)(2) give rise to the largest contribution to the negative thermal expansion.

[Prevalence and risk factors of asymptomatic intracranial vascular stenosis in patients with essential hypertension]

OBJECTIVE

The aim of the study was to determine the prevalence and the distribution pattern of lesion site of intracranial vascular stenosis and to identify risk factors for the stenosis in patients with essential hypertension.

METHODS

A total of 231 consecutive inpatients with essential hypertension were included in this study. Patients with the history of cerebrovascular diseases and relevant neurological symptoms were excluded. Intracranial vascular stenosis (>50% diameter reduction) was detected using CT angiography (CTA).

RESULTS

Of 231 patients, 69 (29.87%) had intracranial artery stenosis. The most common stenosis site is middle cerebral artery (43.69%), followed by carotid siphon (20.39%). The stenosis in internal carotid arterial system (78.64%) was more common than in vertebrobasilar arterial system (21.56%, P < 0.05). The patients with intracranial vascular stenosis were older, had longer history of hypertension, higher levels of systolic blood pressure, higher plasma cholesterol, higher LDL-C. Lp (a), higher urinary microalbumin excretion, thicker ventricular septum, and lower levels of HDL-C than the patients without stenosis. Logistic analysis showed that systolic blood pressure (OR 1.650, 95% CI 1.134 - 2.400, P = 0.023), course of hypertension (OR 1.238, 95% CI 1.072 - 1.429, P = 0.006), LDL-C (OR 2.103, 95% CI 1.157 - 3.823, P = 0.014) and type 2 diabetes (OR 2.325, 95% CI 1.161 - 4.341, P = 0.011) were the independent risk factors of asymptomatic intracranial arterial stenosis.

CONCLUSIONS

Nearly 30% inpatients with essential hypertension had asymptomatic intracranial artery stenosis. The most common site of stenosis was middle cerebral artery. Hypertension, dyslipidemia and diabetes were risk factors for the development of intracranial arterial stenosis.

[Comparison between rapid detection method of enzyme substrate technique and multiple-tube fermentation technique in water coliform bacteria detection]

OBJECTIVE

To compare between rapid detection method of enzyme substrate technique and multiple-tube fermentation technique in water coliform bacteria detection.

METHODS

Using inoculated and real water samples to compare the equivalence and false positive rate between two methods.

RESULTS

Results demonstrate that enzyme substrate technique shows equivalence with multiple-tube fermentation technique (P = 0.059), false positive rate between the two methods has no statistical difference.

CONCLUSION

It is suggested that enzyme substrate technique can be used as a standard method for water microbiological safety evaluation.

Müller glial cells express nestin coupled with glial fibrillary acidic protein in experimentally induced glaucoma in the rat retina

This study was aimed to investigate reactive changes of Müller glial cells in rats subjected to experimentally induced glaucoma. In the latter, it is well documented that elevated intraocular pressure leads to the loss of ganglion cells as confirmed in this study. The present results have shown that Müller glial cells as well as astrocytes closely associated with the ganglion cells reacted vigorously to increased intraocular pressure as manifested by the induced and upregulated expression of nestin and glial fibrillar acidic protein. A major finding in glaucomatous rats was the induced expression of nestin together with glial fibrillar acidic protein with the rise of the intraocular pressure beginning at 2 h. The marked nestin expression appeared to be most intense at 1 week after operation and was sustained at 3 weeks. Induced nestin expression in Müller glial cells was demonstrated unequivocally in whole-mount preparation of the retina. In the same tissue preparation, nestin expression was also detected in some astrocytes. Western blotting analysis confirmed a marked increase in expression of nestin and glial fibrillar acidic protein. Present results suggest that nestin as well as glial fibrillar acidic protein is a useful biomarker for retina injury. The induced expression of these intermediate filament proteins in Müller glial cells especially at their end-feet and also in some astrocytes adjoining the neuronal injury suggests a potential neuroprotective mechanism in response to acute rise in intraocular pressure resulting in neuronal degeneration.

[Raman spectroscopic study of boron carbonitride nanotubes]

Raman spectra of boron carbonitride (BCN) nanotubes made by thermal decomposition under different temperatures and with different catalysts were analyzed. The intensity ratio of D to G band, I(D)/I(G), increases and then decreases with the increase of the temperature. It was indicated that there exists an optimal temperature under which B and N incorporation is maximum. The catalysts influence also the Raman spectra of the BCN nanotubes. I(D)/I(G) is higher with cobalt/ferrocene and nickel/ferrocene than with cobalt, nickel and cobalt/nickel as catalysts. This means that better BCN nanotubes with B and N contents can be produced with the former. The results were confirmed by TEM observation.

Interfacial Tension in Phase-Separated Gelatin/Dextran Aqueous Mixtures

The effect of solute concentrations on interfacial tension was investigated in phase-separated mixtures of dextran and gelatin over a range of concentrations that covered different tie-lines and different positions on one tie-line. The investigations were carried out using equilibrated gelatin-rich and dextran-rich phases in a computer-controlled Couette device at 40 degrees C (above the gelation point of gelatin) and interfacial tensions were measured using the retracting drop method. The results show that the interfacial tension can be related to the length of the tie-line or to the difference in the concentration of dextran (or gelatin) in the separated phases. Interfacial tension increases as either of these parameters increases. For concentrations lying on any single tie-line, the interfacial tension is constant and independent of the concentration of biopolymers. Also, the addition of small amounts of low molecular weight dextran to a dextran-rich phase does not significantly affect the interfacial tension between the gelatine-rich and dextran-rich phases. Experimental results were also compared with theoretical predictions of the interfacial tension using a Flory-Huggins based analysis of the measured tie-line data. Reasonable agreement was found between predicted and measured values, indicating that this approach captures the basic physics of the system.

Effect of acupuncture on plasmic levels of insulin, glucagon and hypercoagulability in NIDDM complicated by acute cerebral infarction

Twenty-one cases of acute cerebral infarction secondary to NIDDM were treated with acupuncture and conventional therapy, and compared with 16 cases treated with conventional therapy alone. The results showed that acupuncture was more effective in reducing insulin and glucagon levels (P < 0.001) and improving hypercoagulability (P < 0.05) of blood.

Preparation and some physicochemical properties of cross-linked poloxamer hydrogel spheres

The principal purpose of this paper is to report the preparation of cross-linked poloxamer hydrogel spheres in an aqueous two-phase system without the use of organic solvent and additional emulsifier and physicochemical properties related to drug release. Poloxamer 188 was modified with methacryloyl chloride to obtain the polymerizable derivative (macromer). The aqueous solution of the macromer was mixed with dextran/magnesium sulfate aqueous solution to form a water-in-water emulsion system. After polymerizing the macromer in the dispersion phase, nonporous particles with a mean diameter of micron level were prepared. Both the mean diameter and swelling ratio of spheres can be tailored by varying the starting composition of the preparations. The drug release experiments indicate that the release of vitamin B12 entrapped in the spheres follows first-order kinetics.

Four-dimensional dielectric property image obtained from electron spectroscopic imaging series

We have demonstrated a new quantitative method to characterize two-dimensional distributions of energy-dependent dielectric function of materials from low loss electron spectroscopic image (ESI) series. Two problems associated with extracted image-spectrum from the low-loss image series, under-sampling and loss of energy resolution, were overcome by using fast Fourier transformation (FFT) interpolation and maximum entropy deconvolution method. In this study, Black Diamond/Si3N4/SiO2/Si-substrate dielectric layer designed for copper metallization was used as the sample. We show that the reconstructed (FFT interpolated and maximum entropy deconvoluted) image-spectrum obtained from ESI series images can be quantified with the same accuracy as conventional electron energy-loss spectroscopy spectra. Since the analysis of the dielectric function is sensitive to the local thickness of the specimen using Kramers-Kronig analysis, we also developed a new method to quantitatively determine the dielectric constant for low-k materials. We have determined the thickness of the Black Diamond using the extrapolated thickness method from the materials of known dielectric constants. Using Kramers-Kronig formula, the dielectric function map can be deduced from two-dimensional reconstructed single scattering spectra with providing the information of thickness. We proposed a four-dimensional data presentation for revealing the uniformity of the energy dependent property. The accuracy of our methods depends on the thickness determination and on the quality of the reconstructed spectra from the image series.

[A resource investigation and commodity identification of Fructus Amomi]

Resource investigation and commodity identification were carried out for 28 samples of Fructus Amomi collected from 7 provinces. The results showed that Fructus Amomi used currently were mainly from the dried ripe-fruit of Amomum villosum, A. villosum var. xanthioides or A. longiligulare. Fructus Amomi in market is nainly A. villosum which comes from Yunnan and Guangdong province.

[Morphological and histological identification and essential oil GC-MS assay of Aralia decaisneana]

This paper reported the studies on morphological and histological diagnostic characteristics and powder feature the root of Aralia decaisneana Hance. Chemical analysis indicates essential oil from root cortex contains at least 16 constituents which trans-caryophllene, 9,12-octadecaienoic acid, etc. are the major ingredients.

Microdialysis sampling coupled to HPLC for transdermal delivery study of ondansetron hydrochloride in rats

The transdermal delivery of ondansetron hydrochloride (ON) solution in propylene glycol (PG) with a widely used penetration enhancer, oleic acid (OA), was studied in rats by a microdialysis sampling technique. Dialysate samples collected from the probe were directly injected into the HPLC system without any pre-treatment and no interference occurred in the blank sample. A good linearity between the standard concentrations and peak areas within the calibration range was achieved. In vivo recovery (32.52 +/- 1.8%) of the probe was assessed with the retrodialysis method, which was used to calculate the ON concentration in the dermis. Oleic acid at the concentrations of 2% and 5% (w/v) increased the steady-state delivery rate from 0.001 to 0.030 and 0.058 microg/h, respectively. OA proved to be an effective enhancer for transdermal delivery of ON in rats.

[Comparison of the components of Ganoderma lucidum and Ganoderma japonicum]

By means of spectrophotometric methods, the contents of polysaccharides about Ganoderma lucidum (including mycelia) and Ganoderma japonicum are determined, HPLC and TLC methods for idntification of their triterpenic acids are given.

[Effects of places and stages on the contents of ganoderic acid B from Ganoderma lucidum]

The paper reports the assay of ganoderic acid B from Ganoderma lucidum in different places and stages by means of HPLC. The results show that contents of ganoderic acid B from different cultured places have differnces, different stages have effect on the amount too.

[Studies on synthesis and analgesic activities of bifentanyl derivatives]

In order to look for potent analgesic compounds and to study the relationships between structures and activities, twenty bifentanyl derivatives were synthesized and their analgesic activities were tested. The structures of the compounds were confirmed by spectral analysis and elemental analysis. Compounds IIa and IIb showed strong analgesic activities in preliminary pharmacological test. Further pharmacological examinations are in progress.