Superconductivity with T c of 116 K discovered in antimony polyhydrides.

Superconductivity (SC) was experimentally observed for the first time in antimony polyhydride. The diamond anvil cell combined with a laser heating system was used to synthesize the antimony polyhydride sample at high pressure and high temperature. In-situ high pressure transport measurements as a function of temperature with an applied magnetic field were performed to study the SC properties. It was found that the antimony polyhydride samples show superconducting transition with critical temperature T c 116 K at 184 GPa. The investigation of SC at magnetic field revealed the superconducting coherent length of ∼40 Å based on the Ginzburg Landau (GL) equation. Antimony polyhydride superconductor has the second highest T c in addition to sulfur hydride among the polyhydrides of elements from main groups IIIA to VIIA in the periodic table.

Salt gradient enhanced sensitivity in nanopores for intracellular calcium ion detection.

Intracellular calcium ion detection is of great significance for understanding the cell metabolism and signaling pathways. Most of the current ionic sensors either face the size issue or sensitivity limit for the intracellular solution with high background ion concentrations. In this paper, we proposed a calmodulin (CaM) functionalized nanopore for sensitive and selective Ca2+ detection inside living cells. A salt gradient was created when the nanopore sensor filled with a low concentration electrolyte was in contact with a high background concentration solution, which enhanced the surface charge-based detection sensitivity. The nanopore sensor showed a 10 × sensitivity enhancement by application of a 100-fold salt gradient, and a detection limit of sub nM. The sensor had a wide detection range from 1 nM to 1 mM, and allowed for quick calcium ion quantification in a few seconds. The sensor was demonstrated for intracellular Ca2+ detection in A549 cells in response to ionomycin.

Record high Tc element superconductivity achieved in titanium.

It is challenging to search for high Tc superconductivity (SC) in transition metal elements wherein d electrons are usually not favored by conventional BCS theory. Here we report experimental discovery of surprising SC up to 310 GPa with Tc above 20 K in wide pressure range from 108 GPa to 240 GPa in titanium. The maximum Tconset above 26.2 K and zero resistance Tczero of 21 K are record high values hitherto achieved among element superconductors. The Hc2(0) is estimated to be ∼32 Tesla with coherence length 32 Å. The results show strong s-d transfer and d band dominance, indicating correlation driven contributions to high Tc SC in dense titanium. This finding is in sharp contrast to the theoretical predications based on pristine electron-phonon coupling scenario. The study opens a fresh promising avenue for rational design and discovery of high Tc superconductors among simple materials via pressure tuned unconventional mechanism.

Superconductivity above 200 K discovered in superhydrides of calcium.

Searching for superconductivity with Tc near room temperature is of great interest both for fundamental science & many potential applications. Here we report the experimental discovery of superconductivity with maximum critical temperature (Tc) above 210 K in calcium superhydrides, the new alkali earth hydrides experimentally showing superconductivity above 200 K in addition to sulfur hydride & rare-earth hydride system. The materials are synthesized at the synergetic conditions of 160~190 GPa and ~2000 K using diamond anvil cell combined with in-situ laser heating technique. The superconductivity was studied through in-situ high pressure electric conductance measurements in an applied magnetic field for the sample quenched from high temperature while maintained at high pressures. The upper critical field Hc(0) was estimated to be ~268 T while the GL coherent length is ~11 Å. The in-situ synchrotron X-ray diffraction measurements suggest that the synthesized calcium hydrides are primarily composed of CaH6 while there may also exist other calcium hydrides with different hydrogen contents.

The Synthesis of a Quasi-One-Dimensional Iron-Based Telluride with Antiferromagnetic Chains and a Spin Glass State.

The report on the superconductivity of the two-legged spin ladders BaFe2S3 and BaFe2Se3 has established 123-type iron chalcogenides as a novel subgroup in the iron-based superconductor family and has stimulated the continuous exploration of other iron-based materials with new structures and potentially novel properties. In this paper, we report the systematic study of a new quasi-one-dimensional (1D) iron-based compound, Ba9Fe3Te15, including its synthesis and magnetic properties. The high-pressure synthesized Ba9Fe3Te15 crystallized in a hexagonal structure that mainly consisted of face-sharing FeTe6 octahedral chains running along the c axis, with a lattice constant of a = 10.23668 Å; this led to weak interchain coupling and an enhanced one-dimensionality. The systematic static and dynamic magnetic properties were comprehensively studied experimentally. The dc magnetic susceptibility showed typical 1D antiferromagnetic characteristics, with a Tmax at 190 K followed by a spin glass (SG) state with freezing at Tf ≈ 6.0 K, which were also unambiguously proved by ac susceptibility measurements. Additionally, X-ray magnetic circular dichroism (XMCD) experiments revealed an unexpected orbital moment for Fe2+, i.e., 0.84 µB per Fe in Ba9Fe3Te15. The transport property is electrically insulating, with a thermal activation gap of 0.32 eV. These features mark Ba9Fe3Te15 as an alternative type of iron-based compound, providing a diverse candidate for high-pressure studies in order to pursue some emerging physics.

Single point mutations enhance activity of cis-epoxysuccinate hydrolase.

OBJECTIVES: To enhance activity of cis-epoxysuccinate hydrolase from Klebsiella sp. BK-58 for converting cis-epoxysuccinate to tartrate. RESULTS: By semi-saturation mutagenesis, all the mutants of the six important conserved residues almost completely lost activity. Then random mutation by error-prone PCR and high throughput screening were further performed to screen higher activity enzyme. We obtained a positive mutant F10D after screening 6000 mutations. Saturation mutagenesis on residues Phe10 showed that most of mutants exhibited higher activity than the wild-type, and the highest mutant was F10Q with activity of 812 U mg(-1) (k cat /K m , 9.8 ± 0.1 mM(-1) s(-1)), which was 230 % higher than that of wild-type enzyme 355 U mg(-1) (k cat /K m , 5.3 ± 0.1 mM(-1) s(-1)). However, the thermostability of the mutant F10Q slightly decreased. CONCLUSIONS: The catalytic activity of a cis-epoxysuccinate hydrolase was efficient improved by a single mutation F10Q and Phe10 might play an important role in the catalysis.

A novel antimicrobial protein isolated from potato (Solanum tuberosum) shares homology with an acid phosphatase.

The nucleotide and amino acids sequences for AP(1) will appear in the GenBank(R) and NCBI databases under accession number AY297449. A novel antimicrobial protein (AP(1)) was purified from leaves of the potato ( Solanum tuberosum, variety MS-42.3) with a procedure involving ammonium sulphate fractionation, molecular sieve chromatography with Sephacryl S-200 and hydrophobic chromatography with Butyl-Sepharose using a FPLC system. The inhibition spectrum investigation showed that AP(1) had good inhibition activity against five different strains of Ralstonia solanacearum from potato or other crops, and two fungal pathogens, Rhizoctonia solani and Alternaria solani from potato. The full-length cDNA encoding AP(1) has been successfully cloned by screening a cDNA expression library of potato with an anti-AP(1) antibody and RACE (rapid amplification of cDNA ends) PCR. Determination of the nucleotide sequences revealed the presence of an open reading frame encoding 343 amino acids. At the C-terminus of AP(1) there is an ATP-binding domain, and the N-terminus exhibits 58% identity with an/the acid phosphatase from Mesorhizobium loti. SDS/PAGE and Western blotting analysis suggested that the AP(1) gene can be successfully expressed in Escherichia coli and recognized by an antibody against AP(1). Also the expressed protein showed an inhibition activity the same as original AP(1) protein isolated from potato. We suggest that AP(1) most likely belongs to a new group of proteins with antimicrobial characteristics in vitro and functions in relation to phosphorylation and energy metabolism of plants.