A QuEChERS-HPLC-MS/MS Method with Matrix Matching Calibration Strategy for Determination of Imidacloprid and Its Metabolites in Procambarus clarkii (Crayfish) Tissues

We developed a method for determination of imidacloprid and its metabolites 5-hydroxy imidacloprid, olefin imidacloprid, imidacloprid urea and 6-chloronicotinic acid in Procambarus clarkii (crayfish) tissues using quick, easy, cheap, effective, rugged, and safe (QuEChERS) and high-performance liquid chromatography-triple quadrupole mass spectrometry. Samples (plasma, cephalothorax, hepatopancrea, gill, intestine, and muscle) were extracted with acetonitrile containing 0.1% acetic acid and cleaned up using a neutral alumina column containing a primary secondary amine. The prepared samples were separated using reverse phase chromatography and scanned in the positive and negative ion multiple reaction-monitoring modes. Under the optimum experimental conditions, spiked recoveries for these compounds in P. clarkii samples ranged from 80.6 to 112.7% with relative standard deviations of 4.2 to 12.6%. The limits of detection were 0.02–0.5 μg·L⁻¹, the limits of quantification were 0.05–2.0 μg·L⁻¹ and the method of quantification was 0.05–2.0 μg·kg⁻¹. The method is rapid, simple, sensitive and suitable for rapid determination and analysis of imidacloprid and its metabolites in P. clarkii tissues.     

2-(2-羟基-3-甲氧基苯基)-C60的合成及在花椰菜花叶病毒启动子DNA传感检测中的应用

通过1,3-偶极[3＋2]环加成反应, 合成了2-(2-羟基-3-甲氧基苯基)-C₆₀吡咯烷衍生物(HMP-C₆₀); 采用红外光谱、 紫外吸收光谱、 元素分析和液相色谱-质谱联用技术对产物的化学结构进行了表征. 基于该衍生物具有功能性的含氮和含氧基团, 通过滴涂法将其修饰在玻碳电极表面上, 并以Zr⁴⁺为桥联试剂将探针DNA通过 5′-PO₄^{3 -}组装到HMP-C₆₀修饰电极表面, 构建了基于HMP-C₆₀修饰电极的电化学DNA传感器. 以[Fe(CN)₆]^3-/4-为电活性探针, 对不同修饰电极进行了电化学表征, 并采用电化学交流阻抗法考察了该传感器对花椰菜花叶病毒(CaMV35S)启动子特征片段的分析性能. 实验结果表明, 在1.0×10^-13 ~ 1.0×10^-9 mol/L浓度范围内, 该电化学传感器电子转移阻抗变化值(ΔR_et)与目标序列浓度对数(lgc_S2)呈现良好的线性关系, 检出限为4.0×10^-14 mol/L (S/N=3). 该传感器能有效识别完全互补序列、 碱基错配序列和非互补序列, 表现出良好的选择性.     

Mapping properties of certain oscillatory integrals on modulation spaces

Suppose β1 α1 ≥0,β2 α2 ≥ 0 and(k,j) ∈R2. In this paper, we mainly investigate the mapping properties of the operator T_αβf(x,y,z)=∫_Q~2f(x-t,y-s,z-t~ks~j)e~(-2πit-β1_s-β2)t~(-1-α1)s~(-1-α2)dtds on modulation spaces, where Q~2 = [0,1] x [0,1] is the unit square in two dimensions.     

Amperometric determination of the activity of protein kinase a using a glassy carbon electrode modified with IgG functionalized gold nanoparticles conjugated to horseradish peroxidase

Microchimica Acta - The authors describe the fabrication of an electrochemical immunosensor for the determination of the activity of protein kinase A (PKA). The method involves (a) electrochemical...     

Can Tetrylone Act in a Similar Fashion to Tetrylene in Ni(CO)2 Complexes? A Theoretical Study based on a Comparison using DFT Calculations

A comparison was made to investigate the structures and bonding of nickel complex that carry tetrylone and tetrylene ligands [(CO)₂Ni‐{E(PH₃)₂}] ( Ni1E ) and [(CO)₂Ni‐{NHE_Me}] ( Ni2E ) (E = C to Pb) using quantum chemical calculations at the BP86 level with various basis sets (SVP, TZVPP, TZ2P+). The nature of the Ni–E bonds was analyzed with charge‐ and energy decomposition methods. The structures of tetrylone complexes Ni1E exhibit an interesting trend with the ligands E(PH₃)₂ are bonded in a tilted orientation relative to the fragment Ni(CO)₂. In contrast, the calculated equilibrium structures of complexes Ni2E exhibit the NHE_Me ligands (E = C to Sn) bonded in a head‐on way to the Ni(CO)₂ fragment, while the bending angle gives the strongest side‐on bonded ligand NHPb_Me when E = Pb. The interesting trend of the bond dissociation energy (BDE) is observed for the tetrylone, which has the same trend BDEs compared with tetrylene complexes. The EDA‐NOCV results indicate that the tetrylone ligands {E(PH₃)₂} in complexes are similar to the tetrylene ligands NHE_Me as strong σ‐donors and weak π‐acceptors. The BDEs calculated for the Ni–E bonds in Ni1E and Ni2E show that the effect of bulky ligands may obscure the intrinsic Ni–E bond strength. The bonding analysis shows that the tetrylone ligands in Ni1E may act in a similar fashion to the tetrylene ligands in Ni2E . All complexes Ni1E and Ni2E are suitable targets for synthesis.     

Bee venom stimulates human melanocyte proliferation, melanogenesis, dendricity and migration

Pigmentation may result from melanocyte proliferation, melanogenesis, migration or increases in dendricity. Recently, it has been reported that secreted phospholipase A(2)(sPLA(2)) known as a component of bee venom (BV), stimulates melanocyte dendricity and pigmentation. BV has been used clinically to control rheumatoid arthritis and to ameliorate pain via its anti-inflammatory and antinociceptive properties. Moreover, after treatment with BV, pigmentation around the injection sites was occasionally observed and the pigmentation lasted a few months. However, no study has been done about the effect of BV on melanocytes. Thus, in the present study, we examined the effect of BV on the proliferation, melanogenesis, dendricity and migration in normal human melanocytes and its signal transduction. BV increased the number of melanocytes dose and time dependently through PKA, ERK, and PI3K/Akt activation. The level of cAMP was also increased by BV treatment. Moreover, BV induced melanogenesis through increased tyrosinase expression. Furthermore, BV induced melanocyte dendricity and migration through PLA(2) activation. Overall, in this study, we demonstrated that BV may have an effect on the melanocyte proliferation, melanogenesis, dendricity and migration through complex signaling pathways in vitro, responsible for the pigmentation. Thus, our study suggests a possibility that BV may be developed as a therapeutic drug for inducing repigmentation in vitiligo skin.     

Organocatalysts wrapped around by poly(ethylene glycol)s (PEGs): a unique host-guest system for asymmetric Michael addition reactions

Asymmetric Michael addition reactions of unmodified ketones to nitroalkenes were performed in PEGs catalyzed by novel pyrrolidinyl-thioimidazolium salts to give products in up to 97% yield and 99% enantioselectivity; ESI mass spectrometric detection for the first time gave evidence of the presence of the PEG-organocatalyst host-guest complex.     

Parallelized integral-direct CIS(D) calculations with multilayer fragment molecular orbital scheme

We have developed a parallelized integral-direct code of the perturbative doubles correction for configuration interaction with singles, proposed as CIS(D) by Head-Gordon et al. (Chem Phys Lett 219:21, 1994). The CIS(D) method provides the energy corrections both of the relaxation and differential correlation for the respective CIS excited states. The implementation of CIS(D) is based on our original algorithm for the second-order Møller–Plesset perturbation (MP2) calculations (Mochizuki et al. in Theor Chem Acc 112:442, 2004). There is no need to communicate bulky intermediate data among worker processes of the parallelized execution. This CIS(D) code is then incorporated into a developer version of ABINIT-MP program, in order to improve the overestimation in excitation energies calculated by the CIS method in conjunction with the multilayer fragment molecular orbital scheme (MLFMO-CIS) (Mochizuki et al. in Chem Phys Lett 406:283, 2005). The MLFMO-CIS(D) method is first used in evaluating the lowest n\(\pi^{*}\) excitation energy of the hydrated formaldehyde. The photoactive yellow protein (PYP) is the second target of MLFMO-CIS(D) calculation. Through these applications, it is shown that the CIS(D) correction improves the CIS results favorably.     

Redox‐Neutral Rhodium‐Catalyzed C?H Functionalization of Arylamine N‐Oxides with Diazo Compounds: Primary C(sp3)?H/C(sp2)?H Activation and Oxygen‐Atom Transfer

An unprecedented rhodium(III)‐catalyzed regioselective redox‐neutral annulation reaction of 1‐naphthylamine N‐oxides with diazo compounds was developed to afford various biologically important 1H‐benzo[g]indolines. This coupling reaction proceeds under mild reaction conditions and does not require external oxidants. The only by‐products are dinitrogen and water. More significantly, this reaction represents the first example of dual functiaonalization of unactivated a primary C(sp³) H bond and C(sp²) H bond with diazocarbonyl compounds. DFT calculations revealed that an intermediate iminium is most likely involved in the catalytic cycle. Moreover, a rhodium(III)‐catalyzed coupling of readily available tertiary aniline N‐oxides with α‐diazomalonates was also developed under external oxidant‐free conditions to access various aminomandelic acid derivatives by an O‐atom‐transfer reaction.