Observation of two resonant structures in e+ e- -->pi+ pi- psi(2S) via initial-state radiation at Belle

The cross section for e+ e- --> pi+ pi- psi(2S) between threshold and sqrt[s]=5.5 GeV is measured using 673 fb(-1) of data on and off the Upsilon(4S) resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the pi+ pi- psi(2S) invariant-mass distribution, one at 4361 +/- 9 +/- 9 MeV/c2 with a width of 74 +/- 15 +/- 10 MeV/c2, and another at 4664 +/- 11 +/- 5 MeV/c2 with a width of 48 +/- 15 +/- 3 MeV/c2, if the mass spectrum is parametrized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.     

Stability analysis of neural networks with interval time-varying delays

The global exponential stability is investigated for neural networks with interval time-varying delays. Based on the Leibniz-Newton formula and linear matrix inequality technique, delay-dependent stability criteria are proposed to guarantee the exponential stability of neural networks with interval time-varying delays. Some numerical examples and comparisons are provided to show that the proposed results significantly improve the allowable upper and lower bounds of delays over some existing ones in the literature.     

Simultaneous Determination of 1-Methyltryptophan and Indoleamine 2,3-Dioxygenase Biomakers of Tryptophan and Kynurenine in Mice Tumors by HPLC–MS/MS

Indoleamine 2,3-dioxygenase (IDO), an immune checkpoint protein, can cause the depletion of tryptophan (Trp) and accumulation of its metabolite of kynurenine (Kyn) in cancer cells, and generates the immunosuppressive microenvironment that supports tumor cell growth. A novel immunoregulatory prodrug micelle based on polyethylene glycol-derivatized an IDO-selective inhibitor of 1-methyltryptophan (1-MT), PEG-Fmoc-1-MT, was developed for inhibiting the IDO activity of the conversion of Trp to Kyn in tumor microenvironments. To investigate the 1-MT distribution and Trp/Kyn ratios in mice tumors with PEG-Fmoc-1-MT prodrug micelles treatment, a HPLC–MS/MS method for simultaneous determination of 1-MT and IDO biomakers of Trp and Kyn in mouse tumors was developed and validated. Triple-quadrupole mass spectrometry with positive electrospray ionization as source ionization in multiple reaction monitoring at m/z 219.0?→?160.1, 205.0?→?118.2, 209.0?→?146.1 and 249.3?→?148.3 was used for determination of 1-MT, Trp, Kyn and matrine (internal standard). The method demonstrated good linearity at the concentrations ranging from 10 to 10,000 ng/mL and lower limits of quantitation of 1 ng/mL for 1-MT, Trp and Kyn, respectively. The validated method was successfully applied to 1-MT tumor biodistribution and Trp/Kyn ratio studies in 4T1 tumor bearing mice i.v. with PEG-Fmoc-1-MT prodrug micelles. The mice tumors with PEG-Fmoc-1-MT prodrug micelles treatment exhibited higher 1-MT accumulation and lower Trp/Kyn ratio, in comparison with those of mice with 1-MT solution treatment. The developed PEG-Fmoc-1-MT prodrug micelles could be a promising IDO immunoregulatory prodrug micelles for cancer immunotherapy.

     

BirA*-protein A fusion protein based BioEnhancer amplifies western blot immunosignal

Western blot (protein immunoblot) is a widely used analytical technique in molecular biology. Utilizing the specific recognizing primary antibody, proteins immobilized on various matrix are investigated by subsequent visualization steps, for example, by the horse radish peroxidase conjugated secondary antibody incubation. Methods to improve the sensitivity in protein identification or quantification are appreciated by biochemists. Herein, we report a new strategy to amplify Western blot signals by constructing a probe with proximal labeling and IgG targeting abilities. The R118G mutation attenuated the biotin-AMP binding affinity of the bacterial biotin ligase BirA*, offering a proximity-dependent labeling ability, which could be used as a signal amplifier. We built a BirA*-protein A fusion protein (BioEnhancer) that specifically binds to IgG and adds biotin tags to its proximal amine groups, enhancing the immunosignal of target proteins. In our experiments, the BioEnhancer system amplified the immunosignal by tenfold compared to the standard western blot. Additionally, our strategy could couple with other signal enhancement methods to further increase the western blot sensitivity.     

Paternal genetic structure of Kyrgyz ethnic group in China revealed by high-resolution Y-chromosome STRs and SNPs

Kyrgyz ethnic group is one of the nomads in China, with the majority in Xinjiang and a small part of them living in Heilongjiang province. Historically, they have went through five migrations westward due to the wars. The name “Kyrgyz” means 40 tribes, originating from the primary groups of Kyrgyz. However, it is a largely understudied population, especially from the Y chromosome. In this study, we used a previously validated high-resolution Y-chromosome single nucleotide polymorphisms (Y-SNPs) and short tandem repeats (Y-STRs) system to study Kyrgyz ethnic group. A total of 314 male samples of Kyrgyz ethnic group were genotyped by 173 Y-SNPs and 27 Y-STRs. After data analysis, the results unveiled that Kyrgyz ethnic group was a population with high percentage of both haplogroup C2a1a3a1d∼-F10091 (91/134) and R1a1a1b2a2-Z2124 (109/134), which has never been reported. This implied that Kyrgyz ethnic group might have gone through bottleneck effects twice, with these two main lineages left. Mismatch analysis indicated that the biggest mismatch number in haplogroup C2a1a3a1d∼-F10091 was 10, while that of haplogroup R1a1a1b2a2-Z2124 was 20. This huge difference reflected the different substructure in two lineages, suggesting that haplogroup C2a1a3a1d∼-F10091 might have the least admixture compared to the other two lineages. After admixture modelling with other datasets, the conclusion could be drawn that Kyrgyz ethnic group had great genetic affinity with Punjabi from Lahore, Pakistan, which supported that Kyrgyz ethnic group in China was close to central Asian.     

Using Terpene Synthase Plasticity in Catalysis: On the Enzymatic Conversion of Synthetic Farnesyl Diphosphate Analogues

Four synthetic farnesyl diphosphate analogues were enzymatically converted with three bacterial sesquiterpene synthases, including β-himachalene synthase (HcS) and (Z)-γ-bisabolene synthase (BbS) from Cryptosporangium arvum, and germacrene A synthase (SmTS6) from Streptomyces mobaraensis. These enzyme reactions not only yielded several previously unknown compounds, showing that this approach opened the door to a new chemical space, but substrates with blocked or altered reactivities also gave interesting insights into the cyclisation mechanisms and the potential to catalyse reactions with different initial cyclisation modes.     

Complex thermal evaluation for 2,2′-azobis(isobutyronitrile) by non-isothermal and isothermal kinetic analysis methods

Azo compounds are widely used in dyes, pigments, blowing agents, and initiators. Unfortunately, these compounds contain the bivalent –N–N– composition which might be cleavaged readily even under high ambient temperature. The self-accelerating decomposition might cause a runaway reaction and lead to a fire or explosion when the cooling system fails or other upsets occur. To investigate the thermal stability parameters of 2,2′-azobis(isobutyronitrile) with thermal hazard and mechanism, differential scanning calorimetry and thermal activity monitor III were applied with non-isothermal method and isothermal method to obtain onset temperature (T ₀), maximum temperature (T _max), and heat of decomposition (ΔH _d). Thermal stability parameters play a pivotal role in thermal analysis, leading particularly to complex evaluation of the inherently safer design during preparation, processing, transport, or storage. The results provide sufficient thermokinetic parameters for process safety in terms of proactive loss prevention program.     

Fiber‐Based Flexible All‐Solid‐State Asymmetric Supercapacitors for Integrated Photodetecting System

Integrated nanodevices with the capability of storing energy are widely applicable and have thus been studied extensively. To meet the demand for flexible integrated devices, all‐solid‐state asymmetric supercapacitors that simultaneously realize energy storage and optoelectronic detection were fabricated by growing Co₃O₄ nanowires on nickel fibers, thus giving the positive electrode, and employing graphene as both the negative electrode and light‐sensitive material. The as‐assembled integrated systems were characterized by an improved energy storage, enhanced power density (at least by 1860 % enhanced) by improving the potential window from 0–0.6 V to 0—1.5 V, excellent photoresponse to white light, and superior flexibility of both the fiber‐based asymmetric supercapacitor and the photodetector. Such flexible integrated devices might be used in smart and self‐powered sensory, wearable, and portable electronics.     

加速溶剂萃取-多层硅胶柱净化-气相色谱串联三重四级杆质谱法测定土壤和沉积物中的多氯萘

通过制作多氯萘(PCNs)在商品多层硅胶柱上的流出曲线、优化气相色谱质谱参数和利用三重四级杆质谱的多重反应监测模式,应用氘代一氯萘#2作为一氯和二氯代萘的定量内标,建立了基于DB-5MS和Rt-βDEXcst两根色谱柱的同位素稀释测定土壤和沉积物中多氯萘的分析方法,实现了两种高毒性六氯代萘#66和#67的基线分离。18种多氯萘同类物校正曲线在1.0~240μg/L浓度范围的相对响应因子为0.70~5.45,相对标准偏差小于18.5%。方法检出限在0.014~0.858μg/L之间,定量限在0.048~2.862μg/L之间。30 m的Rt-βDEXcst色谱柱方法效果优于60 m的DB-5MS色谱柱,但前者耗时较长。实际样品分析表明,7种PCNs回收率标记物,除一氯代萘约为6%外,其余均大于28%。测试土壤和沉积物样品中以低氯代萘为主。