96 research outputs found
Bayesian probability updates using sampling/importance resampling: Applications in nuclear theory
We review an established Bayesian sampling method called sampling/importance resampling and highlight situations in nuclear theory when it can be particularly useful. To this end we both analyse a toy problem and demonstrate realistic applications of importance resampling to infer the posterior distribution for parameters of ΔNNLO interaction model based on chiral effective field theory and to estimate the posterior probability distribution of target observables. The limitation of the method is also showcased in extreme situations where importance resampling breaks
Multiple Unpinned Dirac Points in Group-Va Single-layers with Phosphorene Structure
Emergent Dirac fermion states underlie many intriguing properties of
graphene, and the search for them constitute one strong motivation to explore
two-dimensional (2D) allotropes of other elements. Phosphorene, the ultrathin
layers of black phosphorous, has been a subject of intense investigations
recently, and it was found that other group-Va elements could also form 2D
layers with similar puckered lattice structure. Here, by a close examination of
their electronic band structure evolution, we discover two types of Dirac
fermion states emerging in the low-energy spectrum. One pair of (type-I) Dirac
points is sitting on high-symmetry lines, while two pairs of (type-II) Dirac
points are located at generic -points, with different anisotropic
dispersions determined by the reduced symmetries at their locations. Such
fully-unpinned (type-II) 2D Dirac points are discovered for the first time. In
the absence of spin-orbit coupling, we find that each Dirac node is protected
by the sublattice symmetry from gap opening, which is in turn ensured by any
one of three point group symmetries. The spin-orbit coupling generally gaps the
Dirac nodes, and for the type-I case, this drives the system into a quantum
spin Hall insulator phase. We suggest possible ways to realize the unpinned
Dirac points in strained phosphorene.Comment: 30 pages, 6 figure
Novel sulfamoylamino-containing cephalosporin derivatives, and their in vitro antibacterial properties
Purpose: To prepare and develop new antibacterial agents with novel molecular structures.
Method: A series of novel sulfamoylamino-containing cephalosporin derivatives were synthesized. The in vitro antibacterial effects of the derivatives against Gram-positive bacteria (S. aureus, S. pneumonia and S. epidermidis), and Gram-negative bacteria (E. coli, P. aeruginosa, and K. pneumonia) were investigated.
Results: Compounds 13a and 13b exhibited excellent antibacterial effects against all the Gram-positive and Gram-negative bacteria tested, when compared with other cephalosporin derivatives.
Conclusion: Of these new cephalosporin derivatives, compounds 13a and 13b show the most potent antibacterial activity and would need to be further investigated
In Vitro Study on Apoptosis Induced by Strontium-89 in Human Breast Carcinoma Cell Line
Many radiopharmaceuticals used for medical diagnosis and therapy
are beta emitters; however, the mechanism of the cell death caused
by beta-irradiation is not well understood. The objective of this
study was to investigate the apoptosis of human breast carcinoma
MCF-7 cell lines induced by Strontium-89 (89Sr) and its
regulation and control mechanism. High-metastatic Breast Carcinoma
MCF-7 cells were cultured in vitro using 89Sr with
different radioactive concentration. The inhibition rate of cell
proliferation was measured by MTT color matching method. The cell
cycle retardation, apoptosis conditions, mitochondrion
transmembrane potential difference and Fas expression were tested
and analyzed. The genes P53 and bcl-2 expressions was also
analyzed using immunity histochemical analysis. After being
induced by 89Sr with various of radioactive
concentration, it was found that the inhibition of cell
proliferation of MCF-7 cells was obviously, the retardation of
cell cycle occurred mainly in G2-M. It was also found that the
obvious apoptosis occurred after being induced by 89Sr,
the highest apoptosis rate reached 46.28%. The expressions of
Fas acceptor and P53 gene increased, while bcl-2 gene expression
decreasesd. These findings demonstrate that in the ranges of a
certain radioactive concentration, the inhibition rate of MCF-7
cell proliferation and retardation of cell cycle had positive
correlation with the concentration of 89Sr. And the
mitochondrion transmembrane potential decrease would induce the
apoptosis of MCF-7 cell notably, which were controlled by P53 and
bcl-2 genes, involved with the Fas acceptor
Tris(2,2′-bipyridine-κ2 N,N′)cadmium(II) bis(perchlorate) hemihydrate
The asymmetric unit of the title compound, [Cd(C10H8N2)3](ClO4)2·0.5H2O, consists of one complex [Cd(bpy)3]2+ cation (bpy = 2,2′-bipyridine), two perchlorate anions and one water molecule with half-occupancy. The central cadmium(II) ion is bound to six N atoms from three bpy ligands in a distorted octahedral coordination, with Cd—N bond distances ranging from 2.304 (3) to 2.395 (2) Å
What is ab initio in nuclear theory?
Ab initio has been used as a label in nuclear theory for over two decades. Its meaning has evolved and broadened over the years. We present our interpretation, briefly review its historical use, and discuss its present-day relation to theoretical uncertainty quantification
Large scale experimental study on the fire hazard of buildings’ U-shape façade wall geometry
Buildings have U-shape façade designs for certain purposes such as lighting. However, such designs may lead to a higher fire hazard. In this paper, large scale experiments of upward flame spread over XPS insulation material were conducted to investigate the fire hazard of building’s U-shape façade wall geometry. Comparison to previous laboratory scale experiments were also presented. Theoretical analysis was performed to reveal the mechanism of the U-shape geometry’s influences. It is found that such geometry design would increase the fire hazard of buildings: flame spread rate and flame height increased with U-shape’s geometrical factor. The results agreed with theoretical analysis. It is expected that the buildings’ U-shape façade wall geometry would greatly benefit flame spread for full scale applications and increase the fire hazard. Thus engineers should be careful with such façade wall designs, especially for residential building designs
Low dose triptolide reverses chemoresistance in adult acute lymphoblastic leukemia cells via reactive oxygen species generation and DNA damage response disruption
Chemoresistance represents a major challenge for treatment of acute lymphoblastic leukemia (ALL). Thus, new drugs to overcome chemoresistance in ALL are urgently needed. To this end, we established a cytarabine (araC)-resistant ALL cell line (NALM-6/R), which interestingly displayed cross-resistance towards doxorubicin (ADM). Here we report that low dose of triptolide (TPL), a natural product used for treating inflammatory diseases such as arthritis, could reverse araC and ADM resistance and in NALM-6/R cells as well as primary cells from patients with relapsed or refractory (R/R) ALL, reflected by inhibition of cell proliferation and induction of apoptosis in vitro, and repression of tumor growth in vivo in a mouse xenograft model. Mechanistically, these events were associated with impaired mitochondrial membrane potential and increased reactive oxygen species (ROS) production. Co-treatment with TPL and araC or ADM upregulated pro-apoptotic caspase-9 protein, inhibited checkpoint kinase 1 (Chk1) and 2 (Chk2) phosphorylation, and induced γH2A.X (a DNA damage marker). Notably, the combination regimen of TPL and conventional chemotherapeutics also rapidly diminished tumor burden in a patient with R/R ALL. Together, these findings provide preclinical evidence for repurposing use of TPL in combination with chemotherapeutic agents to treat R/R ALL as an alternative salvage regimen
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