The effects of tilt corrected residual aberration on the detection probability of single-photon propagation in a slant path turbulent atmosphere

Based on the assumption of a pulse laser beam with an initial Gaussian temporal shape and a collimated fundamental-model Gaussian beam, the Rytov approximation and Kolmogorov spectrum model for the index-of-refraction fluctuation of atmosphere, the effect of turbulence on the probability density, acquisition transmittance probability, transmittance probability density, acquisition probability of single-photon propagation in atmospheric communication channel with z-tilt and centroid-tilt aberration corrected are studied theoretically. The probability density, acquisition transmittance probability, transmittance probability density and acquisition probability models for single-photon propagation in uplink path and downlink path are derived. Our results shown that the detection probability and the acquisition transmittance probability of the single-photon are obvious increase, when the beams are propagation in the z-tilt corrected communication channel.     

Study on NCSFs of individual color mechanisms of human vision based on wave-front aberrations

Neural contrast sensitivity functions (NCSFs) of isolated color mechanisms are obtained based on the measurements of wave-front aberrations and isoluminant color contrast sensitivity functions (CSFs). Our study indicates that the mean NCSF and CSF of the red mechanism are higher than those of the green mechanism, respectively, while those of the blue mechanism are the lowest. However, the relative heights of the peak of NCSF and CSF between red and green mechanisms vary in subjects. There are some individuals whose peak values of NCSF and/or CSF of green mechanism are higher than that of the red mechanism. On the other hand, we find that the NCSFs and CSFs of isolated color mechanisms all exhibit the similar characteristics and variation tendency. With the statistical average, the NCSFs of the red, green and blue mechanisms are higher than the corresponding CSFs in the whole spatial frequency. The peaks of the NCSFs of isolated color mechanisms, comparing with the corresponding CSFs curves, shift toward higher spatial frequencies, especially for that of blue mechanism which has a largest shift of 3.9 c/deg.     

利用超高阶导模测量PMN-PT透明陶瓷二次电光系数

以亚毫米尺度的铌镁酸铅-钛酸铅(PMN-PT)透明陶瓷片为导波层制备了对称金属包覆波导,并利用自由空间耦合技术激发了波导中的超高阶导模.根据衰减全反射(ATR)峰的移动,得到了在波导两侧所施加电压与光强反射率的关系,从而计算了PMN-PT透明陶瓷片的二次电光系数.     

Direct Determination of Cu2+ Based on the Electrochemical Catalytic Reaction of Fe3+/Cu2+

Copper ion (Cu²⁺) is one of the heavy metal ions which has been considered as a severe pollutant affecting the environment and human health. Therefore, it is necessary to detect Cu²⁺ sensitively and conveniently in food and drinks. However, the gold standard method that inductively coupled plasma mass spectrometry (ICP‐MS) is expensive equipment required and time‐consuming. In this work, a highly sensitive and facile electrochemical method was studied to directly determine the concentration of Cu²⁺ without cumbersome modification on the surface of glassy carbon electrode (GCE). In the presence of ferric ion (Fe³⁺), Cu²⁺ could play a role of catalyst in the detection system, and the electrochemical signal of differential pulse voltammetry (DPV) response to Cu²⁺ could be amplified obviously. Under the optimal conditions, a good linear relationship was obtained in the range of 1 nM to 5 μM with a detection limit of 57.5 pM (S/N=3) were obtained. Besides, the proposed method has good applicability for the detection of Cu²⁺ in tap water. Furthermore, the copper complex was detected and the results were indicated the proposed method was effective and sensitive.     

Synthesis and application of fluorescent N,S co-doped carbon dots based on on-off-on quenching mode for the collaboration detection of iron ions and ascorbic acid

Nitrogen and sulfur co-doped carbon dots (NS-CDs) were synthesized by one-step solvothermal method using oleic acid as the medium, ʟ-cystine and citric acid monohydrate as precursors. Based on the “on-off-on” fluorescence quenching mode, a novel method was established for determination of both Fe³⁺ and ascorbic acid. The synthesized NS-CDs can be employed as fluorescence chemical sensors for the direct determination of free iron in the aqueous phase and indirect determination of the ascorbic acid contents of vitamin C tablets with linear ranges of 0–10 μM (n = 3) and 0–30 μM (n = 3), and detection limits of 36.6 and 102.5 nM, respectively. These results demonstrate that the proposed method exhibits good selectivity and linearity.     

Engineering polyzwitterion with acylsulfonamide-based betaine structure for protonated switch of surface chemistry at tumoral pH and reductive responsive drug release of polymeric micelles

The surface chemistry of stimulus-responsive nanoparticles plays an important role in mediating nano-bio interactions in cancer nanomedicine by targeting the unique features of the tumor microenvironment, such as low extracellular pH. To develop therapeutic nanoparticles with high sensitivity and instant response to slight pH differences in the systemic circulation, we produced a novel polyzwitterion with acylsulfonamide-based betaine structure by one-step modification of polycarboxybetaine (PCB) with benzene sulfonamide. The zwitterionic micellar shells show high antifouling in the blood circulation and acutely convert into positive charge via acylsulfonamide protonation, thereby improving cell affinity at tumor sites. Moreover, a disulfide bond between the shell and poly-ε-caprolactone (PCL) core allows for reductive-responsive release of doxorubicin (DOX) after internalization of the polymeric micelles. Finally, in vitro and in vivo competition assays demonstrated that dual responsive drug-loaded micelles have better anticancer efficiency than free DOX or micelles without zwitterionic pH-responsive properties. Thus, we have developed a simple and valuable strategy to enhance pH sensitivity of micellar carriers for cancer treatment.     

Quadruple‐Resonance Magic‐Angle Spinning NMR Spectroscopy of Deuterated Solid Proteins

¹H‐detected magic‐angle spinning NMR experiments facilitate structural biology of solid proteins, which requires using deuterated proteins. However, often amide protons cannot be back‐exchanged sufficiently, because of a possible lack of solvent exposure. For such systems, using ²H excitation instead of ¹H excitation can be beneficial because of the larger abundance and shorter longitudinal relaxation time, T₁, of deuterium. A new structure determination approach, “quadruple‐resonance NMR spectroscopy”, is presented which relies on an efficient ²H‐excitation and ²H‐¹³C cross‐polarization (CP) step, combined with ¹H detection. We show that by using ²H‐excited experiments better sensitivity is possible on an SH3 sample recrystallized from 30 % H₂O. For a membrane protein, the ABC transporter ArtMP in native lipid bilayers, different sets of signals can be observed from different initial polarization pathways, which can be evaluated further to extract structural properties.     

1,2,3‐Triazolo[4,5,‐e]furazano[3,4,‐b]pyrazine 6‐Oxide—A Fused Heterocycle with a Roving Hydrogen Forms a New Class of Insensitive Energetic Materials

The straightforward synthesis and energetic properties of a new class of energetic materials, 1,2,3‐triazolo‐ [4,5‐e]furazano[3,4‐b]pyrazine 6‐oxide and its energetic salts are described. They were characterized by IR and multinuclear NMR spectroscopy, elemental analysis, differential scanning calorimetry, and single‐crystal X‐ray diffraction are given. The X‐ray structures show that in the title compound, the hydrogen atom is bonded to the nitrogen in the pyrazine ring; however, in the salts, the negative charge is associated with the triazole nitrogen. Heats of formation for all compounds were calculated with the G2 method and then combined with experimentally determined densities to obtain detonation pressures (P) and velocities (D) by using EXPLO5 program. These new materials exhibit good densities and thermal stabilities, high heats of formation, acceptable detonation properties, and are insensitive to impact.     

Insensitive Nitrogen‐Rich Materials Incorporating the Nitroguanidyl Functionality

A new class of nitroguanidyl‐functionalized nitrogen‐rich materials derived from 1,3,5‐triazine and 1,2,4,5‐tetrazine was synthesized through reactions between N‐nitroso‐N′‐alkylguanidines and the hydrazine derivatives of 1,3,5‐triazine or 1,2,4,5‐tetrazine. These compounds were fully characterized using multinuclear NMR and IR spectroscopies, elemental analysis, and differential scanning calorimetry (DSC). The heats of formation for all compounds were calculated with Gaussian 03 and then combined with experimental densities to determine the detonation pressures (P) and velocities (D_v) of the energetic materials. Interestingly, some of the compounds exhibit an energetic performance (P and D_v) comparable to that of RDX, thus holding promise for application as energetic materials.     

A one-step selective fluorescence turn-on detection of cysteine and homocysteine based on a facile CdTe/CdS quantum dots–phenanthroline system

In this paper, we report a simple, selective, sensitive and low-cost turn-on photoluminescent sensor for cysteine and homocysteine based on the fluorescence recovery of the CdTe/CdS quantum dots (QDs)–phenanthroline (Phen) system. In the presence of Phen, the fluorescence of QDs could be quenched effectively due to the formation of the non-fluorescent complexes between water-soluble thioglycolic acid (TGA)-capped QDs and Phen. Subsequently, upon addition of cysteine and homocysteine, the strong affinity of cysteine and homocysteine to QDs enables Phen to be dissociated from the surface of QDs and to form stable and luminescent complexes with cysteine and homocysteine in solution. Thus, the fluorescence of CdTe/CdS QDs was recovered gradually. A good linear relationship was obtained from 1.0 to 70.0 μM for cysteine and from 1.0 to 90.0 μM for homocysteine, respectively. The detection limits of cysteine and homocysteine were 0.78 and 0.67 μM, respectively. In addition, the method exhibited a high selectivity for cysteine and homocysteine over the other substances, such as amino acids, thiols, proteins, carbohydrates, etc. More importantly, the sensing system can not only achieve quantitative detection of cysteine and homocysteine but also could be applied in semiquantitative cysteine and homocysteine determination by digital visualization. Therefore, as a proof-of-concept, the proposed method has potential application for the selective detection of cysteine and homocysteine in biological fluids.