A Close Binary Star Resolved from Occultation by 87 Sylvia

The star BD+29 1748 was resolved to be a close binary from its occultation by the asteroid 87 Sylvia on 2006 December 18 UT. Four telescopes were used to observe this event at two sites separated by some 80 km apart. Two flux drops were observed at one site, whereas only one flux drop was detected at the other. From the long-term variation of Sylvia, we inferred the probable shape of the shadow during the occultation, and this in turn constrains the binary parameters: the two components of BD+29 1748 have a projected separation of 0.097" to 0.110" on the sky with a position angle 104 deg to 107 deg. The asteroid was clearly resolved with a size scale ranging from 130 to 290 km, as projected onto the occultation direction. No occultation was detected for either of the two known moonlets of 87 Sylvia.Comment: 12 pages, 4 figures, 2 tables; submitted to the PAS

Probing the light harvesting and charge rectification of bismuth nanoparticles behind the promoted photoreactivity onto Bi/BiOCl catalyst by (in-situ) electron microscopy

State-of-the-art electron microscopy has enabled us to investigate microstructural details down to sub-subångström and milli-electron-volt resolution level. The enhanced photoreactivity over bismuth hybridized BiOCl catalyst (Bi/BiOCl) has been reported recently, however, the mechanistic understandings of this improved photoreactivity especially the optical behavior of bismuth nanoparticles (Bi NPs) are still obscured and in debate. The optical absorption features of Bi NPs and the charge transfer characteristic between bismuth and BiOCl have been considered as the major physicochemical origin for the promoted photoreactivity. Based on the advanced (in-situ) electron microscopy of monochromated electron energy loss spectroscopy in scanning transmission electron microscopy imaging mode (Mono-STEM-EELS) along with related theoretical investigations, in this work, we for the first time distinguished and explained the optical absorption originated from the localized surface plasmon resonances (LSPR) effect and direct band gap transition in an individual bismuth nanoparticle as well as transportation of photogenerated carriers at the interface of Bi/BiOCl. These findings could provide better understandings about the origin of the improved photoreactivity of various bismuth-hybridized photocatalysts

Universal scaling functions for bond percolation on planar random and square lattices with multiple percolating clusters

Percolation models with multiple percolating clusters have attracted much attention in recent years. Here we use Monte Carlo simulations to study bond percolation on $L_{1}\times L_{2}$ planar random lattices, duals of random lattices, and square lattices with free and periodic boundary conditions, in vertical and horizontal directions, respectively, and with various aspect ratio $L_{1}/L_{2}$. We calculate the probability for the appearance of $n$ percolating clusters, $W_{n},$ the percolating probabilities, $P$, the average fraction of lattice bonds (sites) in the percolating clusters, $_{n}$ ($_{n}$), and the probability distribution function for the fraction $c$ of lattice bonds (sites), in percolating clusters of subgraphs with $n$ percolating clusters, $f_{n}(c^{b})$ ($f_{n}(c^{s})$). Using a small number of nonuniversal metric factors, we find that $W_{n}$, $P$, $_{n}$ ($_{n}$), and $f_{n}(c^{b})$ ($f_{n}(c^{s})$) for random lattices, duals of random lattices, and square lattices have the same universal finite-size scaling functions. We also find that nonuniversal metric factors are independent of boundary conditions and aspect ratios.Comment: 15 pages, 11 figure

Constitutive Expression of Thermobifida fusca Thermostable Acetylxylan Esterase Gene in Pichia pastoris

A gene encoding the thermostable acetylxylan esterase (AXE) in Thermobifida fusca NTU22 was amplified by PCR, sequenced and cloned into the Pichia pastoris X-33 host strain using the vector pGAPZαA, allowing constitutive expression and secretion of the protein. Recombinant expression resulted in high levels of extracellular AXE production, as high as 526 U/mL in the Hinton flask culture broth. The purified enzyme showed a single band at about 28 kDa by SDS-polyacrylamide gel electrophoresis after being treated with endo-β-N-acetylglycosaminidase H; this agrees with the predicted size based on the nucleotide sequence. About 70% of the original activity remained after heat treatment at 60 °C for three hours. The optimal pH and temperature of the purified enzyme were 8.0 and 60 °C, respectively. The properties of the purified AXE from the P. pastoris transformant are similar to those of the AXE from an E. coli transformant

Explanation of the Gibbs paradox within the framework of quantum thermodynamics

The issue of the Gibbs paradox is that when considering mixing of two gases within classical thermodynamics, the entropy of mixing appears to be a discontinuous function of the difference between the gases: it is finite for whatever small difference, but vanishes for identical gases. The resolution offered in the literature, with help of quantum mixing entropy, was later shown to be unsatisfactory precisely where it sought to resolve the paradox. Macroscopic thermodynamics, classical or quantum, is unsuitable for explaining the paradox, since it does not deal explicitly with the difference between the gases. The proper approach employs quantum thermodynamics, which deals with finite quantum systems coupled to a large bath and a macroscopic work source. Within quantum thermodynamics, entropy generally looses its dominant place and the target of the paradox is naturally shifted to the decrease of the maximally available work before and after mixing (mixing ergotropy). In contrast to entropy this is an unambiguous quantity. For almost identical gases the mixing ergotropy continuously goes to zero, thus resolving the paradox. In this approach the concept of ``difference between the gases'' gets a clear operational meaning related to the possibilities of controlling the involved quantum states. Difficulties which prevent resolutions of the paradox in its entropic formulation do not arise here. The mixing ergotropy has several counter-intuitive features. It can increase when less precise operations are allowed. In the quantum situation (in contrast to the classical one) the mixing ergotropy can also increase when decreasing the degree of mixing between the gases, or when decreasing their distinguishability. These points go against a direct association of physical irreversibility with lack of information.Comment: Published version. New title. 17 pages Revte

Detection of Cartilage Oligomeric Matrix Protein Using a Quartz Crystal Microbalance

Current methods for diagnosing early stage osteoarthritis (OA) based on the magnetic resonance imaging and enzyme-linked immunosorbent assay methods are specific, but require specialized laboratory facilities and highly trained personal to obtain a definitive result. In this work, a user friendly and non-invasive quartz crystal microbalance (QCM) immunosensor method has been developed to detect Cartilage Oligomeric Matrix Protein (COMP) for early stage OA diagnosis. This QCM immunosensor was fabricated to immobilize COMP antibodies utilizing the self-assembled monolayer technique. The surface properties of the immunosensor were characterized by its FTIR and electrochemical impedance spectra (EIS). The feasibility study was based on urine samples obtained from 41 volunteers. Experiments were carried out in a flow system and the reproducibility of the electrodes was evaluated by the impedance measured by EIS. Its potential dynamically monitored the immunoreaction processes and could increase the efficiency and sensitivity of COMP detection in laboratory-cultured preparations and clinical samples. The frequency responses of the QCM immunosensor changed from 6 kHz when testing 50 ng/mL COMP concentration. The linear regression equation of frequency shift and COMP concentration was determined as: y = 0.0872 x + 1.2138 (R2 = 0.9957). The COMP in urine was also determined by both QCM and EIS for comparison. A highly sensitive, user friendly and cost effective analytical method for the early stage OA diagnosis has thus been successfully developed

Fibers and Conductive Films Using Silver Nanoparticles and Nanowires by Near-Field Electrospinning Process

The silver nanowires (AgNWs) and silver nanoparticles (AgNPs) were synthesized. With near-field electrospinning (NFES) process, fibers and thin films with AgNPs and AgNWs were fabricated. In the NFES process, 10 k voltage was applied and the AgNPs and AgNWs fibers can be directly orderly collected without breaking and bending. Then, the characteristics of the fibers were analyzed by four-point probe and EDS. The conductive film was analyzed. When the thickness of films with AgNWs and AgNPs was 1.6 µm, the sheet resistance of films was 0.032 Ω/sq which was superior to that of the commercial ITO. The transmissivity of films was analyzed. The transmissivity was inversely proportional to sheet resistance of the films. In the future, the fibers and films can be used as transparent conductive electrodes

Cryopreservation Preserves Cell-Type Composition and Gene Expression Profiles in Bone Marrow Aspirates From Multiple Myeloma Patients

Single-cell RNA sequencing reveals gene expression differences between individual cells and also identifies different cell populations that are present in the bulk starting material. To obtain an accurate assessment of patient samples, single-cell suspensions need to be generated as soon as possible once the tissue or sample has been collected. However, this requirement poses logistical challenges for experimental designs involving multiple samples from the same subject since these samples would ideally be processed at the same time to minimize technical variation in data analysis. Although cryopreservation has been shown to largely preserve the transcriptome, it is unclear whether the freeze-thaw process might alter gene expression profiles in a cell-type specific manner or whether changes in cell-type proportions might also occur. To address these questions in the context of multiple myeloma clinical studies, we performed single-cell RNA sequencing (scRNA-seq) to compare fresh and frozen cells isolated from bone marrow aspirates of six multiple myeloma patients, analyzing both myeloma cells (CD138+) and cells constituting the microenvironment (CD138-). We found that cryopreservation using 90% fetal calf serum and 10% dimethyl sulfoxide resulted in highly consistent gene expression profiles when comparing fresh and frozen samples from the same patient for both CD138+ myeloma cells (R ≥ 0.96) and for CD138- cells (R ≥ 0.9). We also demonstrate that CD138- cell-type proportions showed minimal alterations, which were mainly related to small differences in immune cell subtype sensitivity to the freeze-thaw procedures. Therefore, when processing fresh multiple myeloma samples is not feasible, cryopreservation is a useful option in single-cell profiling studies

Cove-Edged Chiral Graphene Nanoribbons with Chirality-Dependent Bandgap and Carrier Mobility

Graphene nanoribbons (GNRs) have garnered significant interest due to their highly customizable physicochemical properties and potential utility in nanoelectronics. Besides controlling widths and edge structures, the inclusion of chirality in GNRs brings another dimension for fine-tuning their optoelectronic properties, but related studies remain elusive owing to the absence of feasible synthetic strategies. Here, we demonstrate a novel class of cove-edged chiral GNRs (CcGNRs) with a tunable chiral vector (n,m). Notably, the bandgap and effective mass of (n,2)-CcGNR show a distinct positive correlation with the increasing value of n, as indicated by theory. Within this GNR family, two representative members, namely, (4,2)-CcGNR and (6,2)-CcGNR, are successfully synthesized. Both CcGNRs exhibit prominently curved geometries arising from the incorporated [4]helicene motifs along their peripheries, as also evidenced by the single-crystal structures of the two respective model compounds (1 and 2). The chemical identities and optoelectronic properties of (4,2)- and (6,2)-CcGNRs are comprehensively investigated via a combination of IR, Raman, solid-state NMR, UV-vis, and THz spectroscopies as well as theoretical calculations. In line with theoretical expectation, the obtained (6,2)-CcGNR possesses a low optical bandgap of 1.37 eV along with charge carrier mobility of ∼8 cm2 V-1 s-1, whereas (4,2)-CcGNR exhibits a narrower bandgap of 1.26 eV with increased mobility of ∼14 cm2 V-1 s-1. This work opens up a new avenue to precisely engineer the bandgap and carrier mobility of GNRs by manipulating their chiral vector