An Improved Driving Circuit for Thermo-Optical Switch to Improve the Reliability of Thermo-Optical Switch Matrix

The influence of the heaters on the reliability of the thermo-optic (TO) switch matrix is analyzed and an improved driving circuit based on the analyzed results is designed and fabricated. The circuit can improve the reliability of the switch matrix device from 78.87% to 97.04% for a 4×4 optical switch device with a simplified tree structure. The simulation and experimental results show the circuit can provide suitable driving current for TO switch matrix.

2 x 2 electrooptical switch in silicon-on-insulator waveguide

A 2 x 2 Mach-Zehnder interferometer electrooptical switch integrated in silicon-on-insulator using multimode interference 3-dB couplers as splitter and combiner has been proposed and fabricated. Free carriers plasma dispersion effect was utilized to realize light modulation in silicon. Switching operation was achieved at an injection current of 358mA and which can be much reduced by optimizing the PIN structure and improving fabrication process. Extinction ratio of 7.7dB and crosstalk of 4.8dB has been observed.

The design of cascaded resistors in a new analog switch two-step ADC architecture

In this paper we introduce a new Half-flash analog switch ADC architecture. And we discuss two methods to design the values of the cascaded resistors which generate the reference voltages. Derailed analysis about the effect of analog switches and comparators on reference voltages, and the methods to set the resistor values and correspond;ng voltage errors are given.

An analysis of the performance of a new high-speed single-way analog switch

This paper introduces a new highspeed single-way analog switch which has both highspeed high-resolution mono-direction analog transmission gate function and high-speed digital logic gate function with normal bipolar technology. The analysis of static and transient switching performances as an analog transmission gate is emphasized in the paper. In order to reduce the plug-in effect on high-speed high-resolution systems, an optimum design scheme is also given. This scheme is to achieve accelerated dynamic response with very low bias power dissipation. The analysis of PSPICE simulation as well as the circuit test results confirms the feasibility of the scheme. Now, the circuit has been applied effectively to the designs of novel highspeed A/D and D/A converters.

A one-way MOS analog switch

In this paper, a one-way NMOS analog switch featuring a low plug-in consumption is presented. The performances of analog switch, especially the performances of source follower are simulated under different conditions with PSPICE. Simulation results and factors affecting the deviation between input and output are analyzed, some advice on how to reduce the deviation between input and output is given. Ar the end of the paper, voltage relationship between input and output of the analog switch is obtained. Function of first degree, Vout = kVin + V0, is used to approximate the voltage relationship. The simulation results anti the value achieved from the approximation equation are given as well.

A low noise charge sensitive preamplifier with switch control feedback resistance

In this paper, the design and analysis of a new low noise charge sensitive preamplifier for silicon strip, Si(Li), CdZnTe and CsI detectors etc. with switch control feedback resistance were described, the entire system to be built using the CMOS transistors. The circuit configuration of the CSP proposed in this paper can be adopted to develop CMOS-based Application Specific Integrated Circuit further for Front End Electronics of read-out system of nuclear physics, particle physics and astrophysics research, etc. This work is an implemented design that we succeed after a simulation to obtain a rise time less than 3ns, the output resistance less than 94 Omega and the linearity almost good.

Changes in individual plant traits and biomass allocation in alpine meadow with elevation variation on the Qinghai-Tibetan Plateau

Plant traits and individual plant biomass allocation of 57 perennial herbaceous species, belonging to three common functional groups (forbs, grasses and sedges) at subalpine (3700 m ASL), alpine (4300 m ASL) and subnival (>= 5000 m ASL) sites were examined to test the hypothesis that at high altitudes, plants reduce the proportion of aboveground parts and allocate more biomass to belowground parts, especially storage organs, as altitude increases, so as to geminate and resist environmental stress. However, results indicate that some divergence in biomass allocation exists among organs. With increasing altitude, the mean fractions of total biomass allocated to aboveground parts decreased. The mean fractions of total biomass allocation to storage organs at the subalpine site (7%+/- 2% S.E.) were distinct from those at the alpine (23%+/- 6%) and subnival (21%+/- 6%) sites, while the proportions of green leaves at all altitudes remained almost constant. At 4300 m and 5000 m, the mean fractions of flower stems decreased by 45% and 41%, respectively, while fine roots increased by 86% and 102%, respectively. Specific leaf areas and leaf areas of forbs and grasses deceased with rising elevation, while sedges showed opposite trends. For all three functional groups, leaf area ratio and leaf area root mass ratio decreased, while fine root biomass increased at higher altitudes. Biomass allocation patterns of alpine plants were characterized by a reduction in aboveground reproductive organs and enlargement of fine roots, while the proportion of leaves remained stable. It was beneficial for high altitude plants to compensate carbon gain and nutrient uptake under low temperature and limited nutrients by stabilizing biomass investment to photosynthetic structures and increasing the absorption surface area of fine roots. In contrast to forbs and grasses that had high mycorrhizal infection, sedges had higher single leaf area and more root fraction, especially fine roots.

A simple and sensitive colorimetric pH meter based on DNA conformational switch and gold nanoparticle aggregation

A simple and rapid colorimetric pH meter has been developed based on the conformational switch of i-motif DNA and non-crosslinking AuNP aggregation, the average accuracy of the nano-meter was found to be +/- 0.04 pH unit across the physiological operating range.

[Ru(bpy)2dppz]2+ electrochemiluminescence switch and its applications for DNA interaction study and label-free ATP aptasensor

[Ru(bpy)2dppz]2+ electrochemiluminescence (ECL) was studied, and it was used to investigate DNA interaction and develop a label-free ATP aptasensor for the first time. ECL of [Ru(bpy)2dppz]2+ is negligible in aqueous solution, and increases approximately 1000 times when [Ru(bpy)2dppz]2+ intercalates into the nucleic acid structure. The ECL switch behavior of [Ru(bpy)2dppz]2+ is ascribed to the intercalation that shields the phenazine nitrogens from the solvent and results in a luminescent excited state. The ECL switch by DNA was applied to investigate the interaction of [Ru(bpy)2dppz]2+ with herring sperm DNA. The calculated equilibrium constant (K) is 1.35 x 10(6) M(-1), and the calculated binding-site size (s) is 0.88 base pair, which is consistent with the reported values.

Flourescent Switch Constructed Based on Hemin-Sensitive Anionic Conjugated Polymer and Its Applications in DNA-Related Sensors

Here, a fluorescent switch is constructed combining hemin, hemin aptamer, and a newly synthesized anionic conjugated polymer (ACP), poly(9,9-bis(6'-phosphate-hexyl) fluorenealt-1,4-phenylene) sodium salt (PFHPNa/PFP). In the "off-state", the fluorescence of PFP is sensitively quenched by hemin, with a high K-sv value of similar to 10(7). While in the "on-state", the formation of the aptamer/hemin complex recovers the fluorescence intensity. The fluorescent switch is sensitive and selective to hemin. To testify the universality and practicality of the fluorescent switch, a series of label-free DNA-related sensing platforms are developed, containing three DNA sensing strategies and one ATP recognition strategy. The fluorescent switch developed is simple, sensitive, and universal, which extends applications of the anionic conjugated polymers.

Methylene blue as an indicator for sensitive electrochemical detection of adenosine based on aptamer switch

In this paper, a simple, label-free and regenerative method was proposed to study the interaction between aptamer and small molecule by using methylene blue (MB+) as an electrochemical indicator. A thiolated capture probe containing twelve bases was firstly self-assembled on gold electrode by gold-sulfur affinity. Aptamer probe containing thirty two bases, which was designed to hybridize with capture DNA sequence and specifically recognize adenosine, was then immobilized on the electrode surface by hybridization reaction. MB+ was abundantly adsorbed on the aptamer probe by the specific interaction between MB+ and guanine base in aptamer probe. MB+-anchored aptamer probe can be forced to dissociate from the sensing interface after adenosine triggered structure switching of the aptamer. The peak current of MB+ linearly decreased with the concentration of adenosine over a range of 2 x 10 (8)- x 10 (6) M with a detection limit of 1 x 10 (8) M. In addition, we examined the selectivity of this electrochemical biosensor for cytidine, uridine and guanosine that belonged to the nucleosides family and possessed 1 similar structure with adenosine.

Small-Molecule Selectively Recognizes Human Telomeric G-Quadruplex DNA and Regulates Its Conformational Switch

Structural complexity is an inherent feature of the human telomeric sequence, and it presents a major challenge for developing ligands of pharmaceutical interest. Recent studies have pointed out that the induction of a quadruplex or change of a quadruplex conformation on binding may be the most powerful method to exert the desired biological effect. In this study, we demonstrate a quadruplex ligand that binds selectively to different forms of the human telomeric G-quadruplex structure and regulates its conformational switch. The results show that not only can oxazine750 selectively induce parallel quadruplex formation from a random coil telomeric oligonucleotide, in the absence of added cations, it also can easily surpass the energy barrier between two structures and change the G-quadruplex conformation in Na+ or K+ solution. The combination of its unique properties, including the size and shape of the G-quadruplex and the small molecule, is proposed as the predominant force for regulating the special structural formation and transitions.

Sensitive detection of protein by an aptamer-based label-free fluorescing molecular switch

We report an aptamer-based method for the sensitive detection of proteins by a label-free fluorescing molecular switch (ethidium bromide), which shows promising potential in making protein assay simple and economical.