Mechanical, thermal and degradation properties of poly(d,l-lactide)/poly(hydroxybutyrate-co-hydroxyvalerate)/poly(ethylene glycol) blend

The mechanical, thermal and biodegradable properties of poly(d,l-lactide) (PDLLA), poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) and poly(ethylene glycol) (PEG) blends were studied. The influence of PEG on the tensile and impact strengths of the blends was investigated. The results showed that the toughness and elongation at break of the PDLLA/PHBV (70/30) blends were greatly improved by the addition of PEG, and the notched Izod impact strength increased about 400% and the elongation at break increased from 2.1% to 237.0%. The thermal and degradation properties of the blends were investigated by differential scanning calorimeter (DSC) and thermogravimetric analyzer (TGA), it was found that the thermal stability of PHBV in the presence of PDLLA was improved. The degradation test showed that the addition of PEG could notably accelerate the biodegradation of the blends in the soil at room temperature, and the mass loss is about 20% after 30 days of the storage.     

The filtering behavior of cesium Faraday optical filter

In this paper we investigated cesium Faraday filter at 852 nm in the relatively weak and strong magnetic field theoretically and experimentally. With a cesium cell of 0.02 m in length in an axial magnetic field of 0.06 T, the line-center operation has been achieved. The calculated peak transmission has reached 98.6% with a FWHM bandwidth of only 3.9 GHz, the measured FWHM bandwidth of the filter is 3.29 GHz, which is general agreement with the theoretical result.     

Electrochemical immunosensor based on Pd@Pt/MoS2-Gr for the sensitive detection of CEA

Journal of Solid State Electrochemistry - Here, a BSA/anti-CEA/Pd@Pt/MoS2-Gr/GCE electrochemical immunosensor was constructed to quantitatively detect CEA. By using graphene as a growth framework,...     

From Langmuir–Blodgett films to single molecules

The author recollects his time in the group of D. Möbius in 1985–1986, within the department headed by Hans Kuhn, and the influence of Kuhn's concept of molecular assembly in the gestation of the first single-molecule experiments. He then briefly surveys the recent applications of single-molecule spectroscopy to complex and heterogeneous systems. In particular the field of single-molecule microscopy in membranes and at biological interfaces is now strongly growing, closing the circle back to Langmuir films, the systems which led to the development of single-molecule optical techniques.     

Focus-center problem of planar degenerate system

In this paper we discuss how to determine a degenerate equilibrium of planar analytic systems to be focus-center type. A method of generalized normal sectors is used to determine orbits in exceptional directions near high degenerate equilibria. We obtain a sufficient and necessary condition for the existence of orbits going to origin in a generalized normal sector in class III. Thus, together with some criterions of orbits going to origin in a generic quasi-sector, we can characterize whether the degenerate equilibrium is of focus-center type in every case. The effectiveness of our methods is shown in an example which has a high degenerate equilibrium.     

On a hyperbolic equation arising in electrostatic MEMS

We consider the initial–boundary value problem of a damped wave equation with singular nonlinearity, which describes an electrostatic micro-electro-mechanical system (MEMS) device. The results of the pull-in voltage λ^?${\lambda }^{?}$ being the critical threshold for global existence and quenching are obtained: if the applied voltage λ<λ^?$\lambda <{\lambda }^{?}$, then the equation admits a unique global small solution that exponentially converges to the minimal steady state, while large solution may quench in finite time; if λ>λ^?$\lambda >{\lambda }^{?}$, then any solution quenches in finite time. Finally, in the sense of the viscosity dominated limit, the asymptotic relation of solutions between the hyperbolic equation and the parabolic one is investigated. Also the related error estimates in arbitrary order are derived.     

Advection-mediated competition in general environments

We consider a reaction–diffusion–advection system of two competing species with one of the species dispersing by random diffusion as well as a biased movement upward along resource gradient, while the other species by random diffusion only. It has been shown that, under some non-degeneracy conditions on the environment function, the two species always coexist when the advection is strong. In this paper, we show that for general smooth environment function, in contrast to what is known, there can be competitive exclusion when the advection is strong, and, we give a sharp criterion for coexistence that includes all previously considered cases. Moreover, when the domain is one-dimensional, we derive in the strong advection limit a system of two equations defined on different domains. Uniqueness of steady states of this non-standard system is obtained when one of the diffusion rates is large.     

Study on a novel circulating cooling solid-phase microextraction method

A novel solid-phase microextraction (SPME) setup, circulating cooling solid-phase microextraction (CC-SPME), is developed for determining organochlorine pesticides (OCPs) in water. The linearity area of this method is 0.5-120 microg/l, its RSD value is less than 10% and detection limit is in the low ng/l when it is used to detect gamma-hexachlorocyclohexane, which is better than traditional headspace SPME (HS-SPME) and direct immersion SPME (DI-SPME) methods. The influence of factors such as pH, ionic intensity, adsorption time, and adsorption temperature were also investigated, respectively.     

Effects of nitrogen doping on the properties of Ge15Sb85 phase-change thin film

The effects of nitrogen doping on the chemical bonding state, microstructure, electrical property and thermal stability of Ge₁₅Sb₈₅ film were investigated in detail. The doped N atoms tend to bond with Ge to form Ge₃N₄, as proved by X-ray photoelectron spectroscopy analyses. X-ray diffraction patterns showed that both undoped and N-doped Ge₁₅Sb₈₅ films crystallize into a hexagonal phase very similar to Sb. The thickness reduction upon crystallization for undoped and N-doped Ge₁₅Sb₈₅ films is less than 5%. The crystalline resistivity, crystallization temperature, and thermal stability of amorphous state all increase after nitrogen doping, while the grain size decreases. By adding 7.0 at.% N into the Ge₁₅Sb₈₅ film, the crystalline resistivity increases twelve times and the crystallization temperature increases about 50 °C. The maximum temperature for 10-year retention of amorphous Ge₁₅Sb₈₅ film is estimated to be 147 °C and that of N-doped films is even higher, which will promise better data retention of phase-change random access memory especially in the high-temperature application.     

Antioxidant compounds from propolis collected in Anhui, China

The antioxidant activities of the chloroform, ethyl acetate and n-butanol extract fractions from propolis collected in Anhui, China were evaluated in this study. The ethyl acetate fraction contained the highest amount of total phenolics and total flavonoids, and showed the greatest 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging capacities and Ferric Reducing/Antioxidant Power (FRAP). The antioxidant activity of twenty-two compounds isolated from the ethyl acetate fraction was also evaluated using the above-mentioned three assays. The results indicated that phenolics contributed to the antioxidant activity of propolis collected in Anhui, China. Therefore, propolis collected in Anhui, China and its phenolics might be used as a natural antioxidant.