Charge redistribution and a shortening of the Fe—As bond at the quantum critical point of SmO1–xFxFeAs

Many researchers have pointed out that there is a quantum critical point (QCP) in the F‐doped SmOFeAs system. In this paper, the electronic structure and local structure of the superconductive FeAs layer in SmO_1–xF_xFeAs as a function of the F‐doping concentration have been investigated using Fe and As K‐edge X‐ray absorption spectroscopy. Experiments performed on the X‐ray absorption near‐edge structure showed that in the vicinity of the QCP the intensity of the pre‐edge feature at the Fe‐edge decreases continuously, while there is a striking rise of the shoulder‐peak at the As edge, suggesting the occurrence of charge redistribution near the QCP. Further analysis on the As K‐edge extended X‐ray absorption fine structure demonstrated that the charge redistribution originates mostly from a shortening of the Fe—As bond at the QCP. An evident relationship between the mysterious QCP and the fundamental Fe—As bond was established, providing new insights on the interplay between QCP, charge dynamics and the local structural Fe—As bond in Fe‐based superconductors.     

Trends in ultrashort and ultrahigh power laser pulses based on optical parametric chirped pulse amplification

Since the proof-of-principle demonstration of optical parametric amplification to efficiently amplify chirped laser pulses in 1992,optical parametric chirped pulse amplification(OPCPA)became the most promising method for the amplification of broadband optical pulses.In the meantime,we are witnessing an exciting progress in the development of powerful and ultrashort pulse laser systems that employ chirped pulse parametric amplifiers.The output power and pulse duration of these systems have ranged from a few gigawatts to hundreds of terawatts with a potential of tens of petawatts power level.Meanwhile,the output pulse duration based on optical parametric amplification has entered the range of fewoptical-cycle field.In this paper,we overview the basic principles,trends in development,and current state of the ultrashort and laser systems based on OPCPA,respectively.     

4‐Benzamido‐TEMPO Catalyzed Oxidation of a Broad Range of Alcohols to the Carbonyl Compounds with NaBrO3 under Mild Conditions

4‐Benzamido‐TEMPO catalyzed oxidation system for conversion of a wide range of alcohols to the aldehydes or ketones with NaBrO₃ under room temperature conditions has been developed. The credible, operationally convenient and economical, and condition mild oxidation protocol is particularly of interest in laboratory and in fine chemicals manufacture.     

Capillary electrophoresis with laser-induced fluorescence detection of main polyamines and precursor amino acids in saliva

A hollow-fiber liquid-phase microextraction （HF-LPME） method has been developed for the purification and preconcentration of biogenic polyamines and their precursor amino acids in human saliva. Putrescine （Put）, cadaverine （Cad）, spermidine （Spe）, ornithine （Orn）, lysine （Lys）, and arginine （Arg） were determined by the CE-LIF detection after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, six analytes could achieve baseline separation within 30 min, exhibiting a linear calibration at three orders of magnitude （r2 〉 0.998）; the obtained enrichment factors of HF-LPME were between 19 （for Orn） and 2] 8 （for Cad）, and the LODs were in the range of 0.0072-0.26 nmol/L. The proposed HF-LPME/CE-LIF method has been successfully applied for the sensitive analyses of the real-world saliva samples collected from healthy volunteers and different patients with oral diseases, providing a potential method for primary non-invasive diagnosis of some oral diseases.     

Validation of a Reference Gene (BdFIM) for Quantifying Transgene Copy Numbers in Brachypodium distachyon by Real-Time PCR

Brachypodium distachyon has been proposed as a new model system for gramineous plants with a sequenced genome and an efficient transformation system. Many transgenic B. distachyon plants have been generated in recent years. To develop a reliable fast method for detecting transgenic B. distachyon and quantifying its transgene copy numbers, a species-specific reference gene is of great priority to be validated both in qualitative PCR and quantitative real-time PCR detection. In this study, we first proved that the BdFIM (B. distachyon fimbrin-like protein) gene is a suitable reference gene in qualitative PCR and quantitative real-time PCR for B. distachyon. Fourteen different B. distachyon varieties were tested by both qualitative and quantitative PCRs, and identical amplification products of BdFIM were obtained with all of them, while no amplification products were observed with samples from 14 other plant species, suggesting that BdFIM gene was specific to B. distachyon. The results of Southern blot analysis revealed that the BdFIM gene was low copy number in seven tested B. distachyon varieties. In conclusion, the BdFIM gene can be used as a reference gene, since it had species specificity, low heterogeneity, and low copy number among the tested B. distachyon varieties. Furthermore, the copy number of inserted sequences from transgenic B. distachyon obtained by real-time PCR methods and Southern blot confirmed that the BdFIM gene was an applicable reference gene in B. distachyon.     

Phase transformation and crystalline growth of 4 mol% yttria partially stabilized zirconia

The phase transformation and crystalline growth of 4 mol% yttria partially stabilized zirconia (4Y-PSZ) precursor powders have been investigated using the coprecipitation route, using zirconium oxide chloride octahydrate (ZrOCl₂·8H₂O) and yttrium nitrate (Y(NO₃)₃·6H₂O) as the initial materials. Differential thermal analysis (DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), nano beam electron diffraction (NBED), and high resolution TEM (HRTEM) were utilized to characterize the behavior of phase transformation and crystalline growth of the 4Y-PSZ precursor powders after calcined. Tetragonal ZrO₂ crystallization occurred at about 718.2 K. The activation energy of tetragonal ZrO₂ crystallization was 227.0 ± 17.4 kJ/mol, obtained by a non-isothermal method. The growth morphology parameter (n) and growth mechanism index were close to 2.0, showing that tetragonal ZrO₂ had a plate-like morphology. The crystalline size of tetragonal ZrO₂ increased from 7.9 to 27.6 nm when the calcination temperature was increased from 973 to 1,273 K. The activation energies of tetragonal ZrO₂ growth were 14.97 ± 0.33 and 84.46 ± 6.65 kJ/mol when precursor powders after calcined from 723–973 and 973–1,273 K, respectively.     

Chemical Proteomic Profiling of Protein 4′-Phosphopantetheinylation in Mammalian Cells

Protein 4′-phosphopantetheinylation is an essential post-translational modification (PTM) in prokaryotes and eukaryotes. So far, only five protein substrates of this specific PTM have been discovered in mammalian cells. These proteins are known to perform important functions, including fatty acid biosynthesis and folate metabolism, as well as β-alanine activation. To explore existing and new substrates of 4′-phosphopantetheinylation in mammalian proteomes, we designed and synthesized a series of new pantetheine analogue probes, enabling effective metabolic labelling of 4′-phosphopantetheinylated proteins in HepG2 cells. In combination with a quantitative chemical proteomic platform, we enriched and identified all the currently known 4′-phosphopantetheinylated proteins with high confidence, and unambiguously determined their exact sites of modification. More encouragingly, we discovered, using targeted chemical proteomics, a potential 4′-phosphopantetheinylation site in the protein of mitochondrial dehydrogenase/reductase SDR family member 2 (DHRS2).