Polarization beam splitter based on dielectric periodic structure with different EFCs for two polarizations

A dielectric multi-layered structure is studied in this letter. It is found that at some frequency ranges, the equal-frequency contours (EFCs) are almost flat for one polarization but still curve for the other. Based on this property, we propose a novel polarization beam splitter.     

大学物理实验教学体系改革与实践

本文就大学物理实验的教学体系、教学模式改革进行了探讨和实践。     

Compression evaluation of surgery video recordings retaining diagnostic credibility (compression evaluation of surgery video)

Wider dissemination of medical digital video libraries is affected by two correlated factors, resource effective content compression that directly influences its diagnostic credibility. It has been proved that it is possible to meet these contradictory requirements halfway for long-lasting and low motion surgery recordings at compression ratios close to 100 (bronchoscopic procedures were a case study investigated). As the main supporting assumption, it has been accepted that the content can be compressed as far as clinicians are not able to sense a loss of video diagnostic fidelity (a visually lossless compression). Different market codecs were inspected by means of the combined subjective and objective tests toward their usability in medical video libraries. Subjective tests involved a panel of clinicians who had to classify compressed bronchoscopic video content according to its quality under the bubble sort algorithm. For objective tests, two metrics (hybrid vector measure and hosaka Plots) were calculated frame by frame and averaged over a whole sequence.     

On the choice of the regularization parameter for the interpretation of ARXPS data using a multilayer model

We report our investigation of the dependence of the profile extracted from ARXPS data on the value of the regularization parameter α. We argue that a choice based upon the L-curve criterion, which does not require knowledge of the variances in the data, is less satisfactory than an approach based on choosing α such that χ²/N = 1.     

Analysis of a separate 1319 and 1338 nm Nd:YAG laser with a blazing grating

We develop a separate 1319 and 1338 nm Nd:YAG laser system with a blazing grating (600 lines/mm). The resonator of this system has a Littrow grating configuration and a highly reflective mirror, in which the zero-order diffraction of the grating acts as the laser output. By virtue of the wavelength-dependent reflectivity of the grating, a single-wavelength laser at 1319 nm or 1338 nm can be realized. In view of the laser rate equations and using the distribution of the blazing grating, we analyze the oscillation conditions providing single-wavelength laser operation in the system.     

Calculation of electron wave functions and refractive index of Ne

The radial wave functions of inner electron shell and outer electron shell of a Ne atom were obtained by the approximate analytical method and tested by calculating the ground state energy of the Ne atom. The equivalent volume of electron cloud and the refractive index of Ne were calculated. The calculated refractive index agrees well with the experimental result. Relationship between the refractive index and the wave function of Ne was discovered. Supported by the New Star Program of Beijing Science and Technology, China (Grant No. 952870400), the Beijing Municipal Commission of Education, and the Excellent Young Teachers Program of Ministry of Education, China     

Study of Temperature and UV Wavelength Range Effects on Degradation of Photo-Irradiated Polyethylene Films Using DMA

Plastic bags mostly made of polyethylene (PE) cause pollution as solid waste due to their non-degradability nature. Initiation of a degradative process by enhanced photo-oxidation is a possible method for an accelerated degradation. This paper presents temperature treatment effects on PE films where photodegradation was initiated using ultraviolet (UV) irradiation in the ranges of 200–300 nm and 300–400 nm for 2 hr. Effects of temperature of 40°C and 55°C on non-UV-irradiated and UV-irradiated PE films processed by conventional methods were investigated and evaluated after 50 hr, 150 hr, and 350 hr of temperature exposure. The effects of UV wavelength range irradiation on the degradation were deduced. Measuring the dynamic moduli using a dynamic mechanical analyzer monitored the degradation. The decrease in average storage modulus was 62% with treatment at 55°C, higher than the 16% drop at 40°C for unirradiated samples after 350-hr exposure. Cross-linking in UV-exposed samples, characterized by an increase in dynamic modulus (stiffening), was observed followed by a reduction of storage modulus. Temperature treatment at 55°C together with 300–400-nm UV range irradiation resulted in the largest increase, i.e., 22% after 150 hr, followed by the largest reduction of storage modulus, i.e., 74.6% for a cumulative 350-hr exposure.     

Rheological Behaviors of Poly(Vinylidene Fluoride)/“Bud-Branched” Nanotubes Nanocomposites

Bud-branched nanotubes, fabricated by growing metal particles on the surfaces of multiwall carbon nanotubes (MWCNTs), were used to prepare poly(vinylidene fluoride) (PVDF)-based nanocomposites. The melt viscoelastic behaviors of PVDF and its nanocomposites were characterized. The results showed that the introduction of both the MWCNTs and bud-branched nanotubes (MWCNTs-B) increased the storage modulus, loss modulus, and complex viscosity of the nanocomposites. However, the bud-branched nanotubes were more efficient to increase the elasticity than the MWCNTs that have relatively smooth surfaces. In particular, it was observed that the bud-branched nanotubes caused an increase of normal force and crossover modulus, while for MWCNTs, no variation in the normal force and a decrease of the crossover modulus were observed.     

Warm-white light-emitting diodes integrated with colloidal quantum dots for high luminous efficacy and color rendering

Warm-white LEDs (WLEDs) with high spectral quality and efficiency are required for lighting applications, but current experimental performances are limited. We report on nanocrystal quantum dot (NQD) hybridized WLEDs with high performance that exhibit a high luminous efficacy of optical radiation exceeding 350lm/W(opt) and a high color rendering index close to 90 at a low correlated color temperature <3000K. These spectrally engineered WLEDs are obtained using a combination of CdSe/ZnS core/shell NQD nanophosphors integrated on blue InGaN/GaN LEDs.     

Zirconium-doped hybrid films patterned by soft lithography for distributed-feedback lasers

Zirconium (Zr)-doped hybrid films containing Rhodamine 6G (Rh6G) were prepared by spin-coating on glass substrates with different Zr–Si molar ratio. Second-order distributed-feedback (DFB) resonators with large surface-relief modulation depth over 160 nm could be fabricated by soft lithographic technique using a polydimethylsiloxane (PDMS) replica. Optically pumped by a pulsed frequency-doubled Q-switched Nd:YAG laser, the emission wavelength of the DFB-lasers can be tuned over 16 nm by changing the grating period. With the optimization of the Zr–Si molar ratio, low laser threshold of 3 μJ/mm² was obtained.