A fundamental study on the fluorescence-quenching effect of nitro groups in tetraphenylethene AIE dyes with electron-withdrawing groups

A nitro group is a common fluorescence quencher,but its quenching efficiency can be easily affected by the surrounding environment.To date,there has been no systematic study on the effects of electronwithdrawing groups on the quenching efficiency of nitro groups.Herein,by virtue of experimental validation and theoretical calculations,we found that strong electron-withdrawing groups,such as pyridinium and dicyanovinyl groups,are detrimental to the quenching effect of nitro groups.Decreasing the electron-withdrawing ability could restore the nitro group’s quenching effect.

Effect of Melt Quenching on Martensite Transformation in Fe-Ni Alloy

The main features of martensite transformation in melt-quenched Fe-31.4% Ni alloy on cooling below room temperature have been studied. It is found that the ribbon 50～60 μm thick, prepared by spinning technique, is a natural composite in which isothermal and surface martensite are not formed, while athermal martensite forms at lower temperature, all factors being the same, as compared to the alloy of the same composition and grain size, prepared by recrystallization.

Carbon dots derived from Poria cocos polysaccharide as an effective“on-off”fluorescence sensor for chromium(Ⅵ)detection

Chromium is a harmful contaminant showing mutagenicity and carcinogenicity.Therefore,detection of chromium requires the development of low-cost and high-sensitivity sensors.Herein,blue-fluorescent carbon quantum dots were synthesized by one-step hydrothermal method from alkali-soluble Poria cocos polysaccharide,which is green source,cheap and easy to obtain,and has no pharmacological activity due to low water solubility.These carbon quantum dots exhibit good fluorescence stability,water solubility,anti-interference and low cytotoxicity,and can be specifically combined with the detection of Cr(Ⅵ)to form a non-fluorescent complex that causes fluorescence quenching,so they can be used as a label-free nanosensor.High-sensitivity detection of Cr(Ⅵ)was achieved through internal filtering and static quenching effects.The fluorescence quenching degree of carbon dots fluorescent probe showed a good linear relationship with Cr(Ⅵ)concentration in the range of 1-100μM.The linear equation was F;/F=0.9942+0.01472[Cr(Ⅵ)](R;=0.9922),and the detection limit can be as low as 0.25μM(S/N=3),which has been successfully applied to Cr(Ⅵ)detection in actual water samples herein.

Unquenched Effects and Quark Mass Dependence of Lattice Gluon Propagator in Infrared Region

In this paper, the gluon propagator in Landau gauge has been studied on a lattice, including the quenched and the unquenched one. The small geometry size of lattice we use is 16^3 × 32, and the big one is 20^3 × 64. For the quenched approximation, we fit the numerical results and give a little different fitting values. We also obtain unquenched effects by comparing the gluon propagator resulting from the quenched and unquenched configurations, for both the two-flavor and three-flavor cases. For the unquenched configurations, an obvious quark mass dependence has not been found in the small quark mass case, but is found in the three-flavor case when the quark mass is big.

PIPBQ Effect Aware SER Analysis for Combinational Logic Circuits

Technology scaling results in the propagation-induced pulse broadening and quenching（PIPBQ） effect become more noticeable.In order to effectively evaluate the soft error rate for combinational logic circuits,a soft error rate analysis approach considering the PIPBQ effect is proposed.As different original pulse propagating through logic gate cells,pulse broadening and quenching are measured by HSPICE.After that,electrical effect look-up tables（EELUTs） for logic gate cells are created to evaluate the PIPBQ effect.Sensitized paths are accurately retrieved by the proposed re-convergence aware sensitized path search algorithm.Further,by propagating pulses on these paths to simulate fault injection,the PIPBQ effect on these paths can be quantified by EELUTs.As a result,the soft error rate of circuits can be effectively computed by the proposed technique.Simulation results verify the soft error rate improvement comparing with the PIPBQ-not-aware method.

Influence of pre-stretching on quench sensitive effect of high-strength Al-Zn-Mg-Cu-Zr alloy sheet

The influence of pre-stretching on quench sensitive effect of high strength Al-Zn-Mg-Cu-Zr alloy AA 7085 sheet was investigated by tensile testing at room temperature,transmission electron microscopy(TEM)and differential scanning calorimetry(DSC).The water-cooled and aged alloy exhibits higher strength than the air-cooled and aged alloy;2.5%pre-stretching of tensile deformation exerts little effect on strength of water-cooled and aged alloy but increases that of air-cooled and aged one,and therefore the yield strength reduction rate due to slow quenching decreases from about 3.8%to about 1.0%,reducing quench sensitive effect.For the air-cooled alloy,pre-stretching increases the sizes ofη'strengthening precipitates but also increases their quantity and the ratio of diameter to thickness,resulting in enhanced strengthening and higher strength after aging.The reason has been discussed based on microstructure examination by TEM and DSC.

Effect of Quench Treatment on Fe/Mo Order and Magnetic Properties of Double Perovskite Sr_2FeMoO_6

A quench-treatment technique is used to prepare a high-quality polycrystalline sample of double perovskite Sr2FeMo06 （SFMO）. X-ray powder diffraction analysis reveals that the sample has a single phase and exhibits I4/m symmetry. The cation order η of the sample increases to 98.9（2）% from 94.2（3）%, which is prepared by the traditional sol-gel method. The initial magnetization isotherm of the sample is detected at 300 K. Unit-cell magnetization for the current sample is 1.332 #s at 300 K, and the one for the traditional sol-gel method sample is 0.946#9. Unit-cell magnetization is enhanced to 40.80% by the quench-treatment technique. Quench treatment is an effective method of enhancing the Fe/Mo order and magnetic properties of double perovskite SFMO.

Solid Solution Sm_(1+x)Ba_(2-x)Cu_3O_y and Effect of Quench Temperature on SmBa_2Cu_3O_y

By X-ray powder diffraction technique and oxygen content analysis, a solid solution Sm1+xBa2-xCu3Oy has been determined in the range 0≤x≤0.4. When x<0.25. the Sm1+xBa2-xCu3Oy presents orthorhombic symmetry, and the orthorhombic-tetragonaJ transition ocCurs at x = 0.25. With the increase of x, TC decreases and finally breaks. The correlation between ox ygen content and phase structure at different quench temperatures related to Sm Ba2Cu3Oy has been investigated as well

The dual role of multiple-transistor charge sharing collection in single-event transients

As technologies scale down in size, multiple-transistors being affected by a single ion has become a universal phenomenon, and some new effects are present in single event transients （SETs） due to the charge sharing collection of the adjacent multiple-transistors. In this paper, not only the off-state p-channel metal–oxide semiconductor field-effect transistor （PMOS FET）, but also the on-state PMOS is struck by a heavy-ion in the two-transistor inverter chain, due to the charge sharing collection and the electrical interaction. The SET induced by striking the off-state PMOS is efficiently mitigated by the pulse quenching effect, but the SET induced by striking the on-state PMOS becomes dominant. It is indicated in this study that in the advanced technologies, the SET will no longer just be induced by an ion striking the off-state transistor, and the SET sensitive region will no longer just surround the off-state transistor either, as it is in the older technologies. We also discuss this issue in a three-transistor inverter in depth, and the study illustrates that the three-transistor inverter is still a better replacement for spaceborne integrated circuit design in advanced technologies.

Effect of concentration quenching on the spectroscopic properties of Er^(3+)/Yb^(3+) co-doped AlF_3-based glasses

A series of highly Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses have been investigated in order to develop a microchip laser at 1.54 μm under 980 nm excitation. Measurements of absorption, emission and upconversion spectra have been performed to examine the effect of Er^(3+)/Yb^(3+) concentration quenching on spectroscopic properties. In the glasses with Er^(3+) concentrations below 10 mol%, concentration quenching is very low and the Er^(3+)/Yb^(3+) co-doped fluoroaluminate glasses have stronger fluorescence of 1.54μm due to the ~4I_(13/2)→~4I_(15/2) transition than that of Er^(3+) singly-doped glasses. As Er^(3+) concentrations above 10 mol% in the Er^(3+)/Yb^(3+) co-doped samples, concentration quenching of 1.54μm does obviously occur as a result of the back energy transfer from Er^(3+) to Yb^(3+). To obtain the highest emission efficiency at 1.54μm, the optimum doping-concentration ratio of Er^(3+)/Yb^(3+) was found to be approximately 1:1 in mol fraction when the Er^(3+) concentration is less than 10 mol%.

Analysis of process variations impact on the single-event transient quenching in 65 nm CMOS combinational circuits

Single-event transient pulse quenching （Quenching effect） is employed to effectively mitigate WSET （SET pulse width）. It en- hanced along with the increased charge sharing which is norm for future advanced technologies. As technology scales, param- eter variation is another serious issue that significantly affects circuit＇s performance and single-event response. Monte Carlo simulations combined with TCAD （Technology Computer-Aided Design） simulations are conducted on a six-stage inverter chain to identify and quantify the impact of charge sharing and parameter variation on pulse quenching. Studies show that charge sharing induce a wider WSET spread range. The difference of WSET range between no quenching and quenching is smaller in NMOS （N-Channel Metal-Oxide-Semiconductor Field-Effect Transistor） simulation than that in PMOS＇ （P-Channel Met- N-Oxide-Semiconductor Field-Effect Transistor）, so that from parameter variation view, quenching is beneficial in PMOS SET mitigation. The individual parameter analysis indicates that gate oxide thickness （TOXE） and channel length variation （XL） mostly affect SET response of combinational circuits. They bring 14.58% and 19.73% average WSET difference probabilities for no-quenching cases, and 105.56% and 123.32% for quenching cases.

Measurement of proton quenching in a LAB-based liquid scintillator

Background The linear alkylbenzene has been recently used as the solvent of liquid scintillator by several neutrino experiments.The nonlinear energy response induced by the ionization quenching is critical in this kind of detectors.An empirical model proposed by Birks is commonly used to describe the quenching effect;however,recently,the parameter kB in the model is found to be particle dependent.Purpose To improve the understanding of proton quenching in LS detectors.Methods A 14 MeV D–T compact neutron generator is deployed which can provide recoil protons with kinetic energies ranging from 0.5 to 13 MeV in LS.Results The parameter kB is extracted by fitting the data to the Birks’law prediction with careful examination of systematic uncertainties.Conclusion The measurement will contribute to the in-depth understanding of the energy nonlinearity in liquid scintillator detectors.

Microstructure and Tensile Properties of a Nb–Mo Microalloyed 6.5Mn Alloy Processed by Intercritical Annealing and Quenching and Partitioning

The transformation behavior, microstructural evolution and mechanical properties were compared in a coldrolled Nb–Mo microalloyed 6.5Mn alloy after intercritical annealing（IA） and quenching and partitioning（Q ＆ P）,respectively. The thermodynamic calculation and theoretical analysis were used to determine the optimal heat treatment parameters. The Q ＆ P samples exhibited relatively higher strength with relatively low ductility, mainly due to the hard martensite matrix, which resulted in continuous yielding behavior upon loading, whereas the IA samples showed the significantly improved ductility, which benefited from the more sufficient transformation-induced plasticity（TRIP） effects and the softer ultrafine ferrite matrix. The dependence of yield point elongation（YPE） of IA samples on grain size demonstrated that the YPE value was in the reverse proportional relationship to the average grain size, which agreed well with theoretical analysis.

N,P Co-Doped Carbon Dots as Multifunctional Fluorescence Nano-Sensor for Sensitive and Selective Detection of Cr(Ⅵ) and Ascorbic Acid

It is particularly important to monitor Cr(Ⅵ)for its high toxicity.In this paper,a novel,simple,low-cost and"on-off-on"fluorescence sensor of carbon dots doped with nitrogen and phosphorus(N,P-CDs)was developed via one-step hydrothermal method for highly sensitive and good selective detection of Cr(Ⅵ)and ascorbic acid(AA).The prepared N,P-CDs exhibited the ability for detection of Cr(Ⅵ)based on the inner filter effect(IFE)and static quenching.Under optimized conditions,the fluorescence quenching efficiency of N,P-CDs showed a good linear correlation with Cr(Ⅵ)concentration ranged from0.68 to 87.38μmol/L(R^(2)=0.9946).The limit of detection(LOD)was 0.18μmol/L,which was acceptable compared with the maximum Cr(Ⅵ)concentration of 0.96μmol/L in drinking water prescribed by WHO.In addition,the N,P-CDs/Cr(Ⅵ)hybrid were also used as"turn-on"fluorescent transducers for detecting AA with a wide linear region ranged from 0.02 to933.33μmol/L(R^(2)=0.9972).Furthermore,the N,P-CDs fluorescence sensor had admissible applicability for Cr(Ⅵ)and AA detection in actual water samples with acceptable recovery rate,indicating that the fluorescence sensor had great application potential in environmental monitoring and food field.

Selective detection of phosphaphenanthrene-containing luminophors with aggregation-induced emission enhancement to transition metal ions

Transition metal ions(Pb^(2+),Zn^(2+),Cd^(2+),Co^(2+),Mn^(2+),Cu^(2+),Ni^(2+),Hg^(2+),Ag^(+),Fe^(3+))in water are used to quench emission of 2-(6-oxido-6H-dibenz<c,e><1,2>oxaphosphorin-6-yl)-1,4-phenylene-bis(p-pentyloxylbenzoate)s(MD5)with aggregation-induced emission enhancement(AIEE)in water-acetonitrile(AN)mixture(80:20 by volume).Among all metal ions,Fe^(3+)exhibits the highest quenching efficiency on AIEE of MD5 even when the concentration of Fe^(3+)is lower than 1×10^(-6) mol/L.The quenching efficiency of Hg^(2+)is lower than that of Fe^(3+)at the same concentration,though MD5 is used to detect Hg^(2+)efficiently,too.To other metal ions,low quenching efficiency has few relations with a wider concentration range.The UV absorbance spectra show only red shift of absorbance wavelength in the presence of Hg^(2+)and Fe^(3+),which indicates a salt-induced Jaggregation.SEM photos reveal larger aggregation and morphological change of nanoparticles of MD5 in water containing Hg^(2+)and Fe^(3+),which reduce the surface area of MD5 emission for further aggregation.The selective quenching effect of transition metal ions to emission of MD5 has a potential application in chemical sensors of some metal ions.