590 research outputs found
Designing rigid carbon foams
We use ab initio density functional calculations to study the stability,
elastic properties and electronic structure of sp2 carbon minimal surfaces with
negative Gaussian curvature, called schwarzites. We focus on two systems with
cubic unit cells containing 152 and 200 carbon atoms, which are metallic and
very rigid. The porous schwarzite structure allows for efficient and reversible
doping by electron donors and acceptors, making it a promising candidate for
the next generation of alkali ion batteries. We identify schwarzite structures
that act as arrays of interconnected quantum spin dots or become magnetic when
doped. We introduce two interpenetrating schwarzite structures that may find
their use as the ultimate super-capacitor.Comment: 6 pages, 5 figure
Exploring Zeptosecond Quantum Equilibration Dynamics: From Deep-Inelastic to Fusion-Fission Outcomes in Ni+Ni Reactions
Energy dissipative processes play a key role in how quantum many-body systems
dynamically evolve towards equilibrium. In closed quantum systems, such
processes are attributed to the transfer of energy from collective motion to
single-particle degrees of freedom; however, the quantum many-body dynamics of
this evolutionary process are poorly understood. To explore energy dissipative
phenomena and equilibration dynamics in one such system, an experimental
investigation of deep-inelastic and fusion-fission outcomes in the
Ni+Ni reaction has been carried out. Experimental outcomes have
been compared to theoretical predictions using Time Dependent Hartree Fock and
Time Dependent Random Phase Approximation approaches, which respectively
incorporate one-body energy dissipation and fluctuations. Excellent
quantitative agreement has been found between experiment and calculations,
indicating that microscopic models incorporating one-body dissipation and
fluctuations provide a potential tool for exploring dissipation in low-energy
heavy ion collisions.Comment: 11 pages, 9 figures, 1 table, including Supplemental Material -
Version accepted for publication in Physical Review Letter
Hepatocytes infected with hepatitis C virus change immunological features in the liver microenvironment
Hepatitis C virus (HCV) infection is remarkably efficient in establishing viral persistence, leading to the development of liver cirrhosis and hepatocellular carcinoma (HCC). Direct-acting antiviral agents (DAAs) are promising HCV therapies to clear the virus. However, recent reports indicate potential increased risk of HCC development among HCV patients with cirrhosis following DAA therapy. CD8+ T-cells participate in controlling HCV infection. However, in chronic hepatitis C patients, severe CD4+ and CD8+ T-cell dysfunctions have been observed. This suggests that HCV may employ mechanisms to counteract or suppress the host T-cell responses. The primary site of viral replication is within hepatocytes where infection can trigger the expression of costimulatory molecules and the secretion of immunoregulatory cytokines. Numerous studies indicate that HCV infection in hepatocytes impairs antiviral host immunity by modulating the expression of immunoregulatory molecules. Hepatocytes expressing whole HCV proteins upregulate the ligands of programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and transforming growth factor β (TGF-β) synthesis compared to those in hepatocytes in the absence of the HCV genome. Importantly, HCV-infected hepatocytes are capable of inducing regulatory CD4+ T-cells, releasing exosomes displaying TGF-β on exosome surfaces, and generating follicular regulatory T-cells. Recent studies report that the expression profile of exosome microRNAs provides biomarkers of HCV infection and HCV-related chronic liver diseases. A better understanding of the immunoregulatory mechanisms and identification of biomarkers associated with HCV infection will provide insight into designing vaccine against HCV to bypass HCV-induced immune dysregulation and prevent development of HCV-associated chronic liver diseases
Reduced quasifission competition in fusion reactions forming neutron-rich heavy elements
Measurements of mass-angle distributions (MADs) for Cr + W reactions,
providing a wide range in the neutron-to-proton ratio of the compound system,
(N/Z)CN, have allowed for the dependence of quasifission on the (N/Z)CN to be
determined in a model-independent way. Previous experimental and theoretical
studies had produced conflicting conclusions. The experimental MADs reveal an
increase in contact time and mass evolution of the quasifission fragments with
increasing (N/Z)CN, which is indicative of an increase in the fusion
probability. The experimental results are in agreement with microscopic
time-dependent Hartree-Fock calculations of the quasifission process. The
experimental and theoretical results favor the use of the most neutron-rich
projectiles and targets for the production of heavy and superheavy nuclei.Comment: Accepted to PRC as a Rapid Communicatio
A phase II study of S-1 monotherapy administered for 2 weeks of a 3-week cycle in advanced gastric cancer patients with poor performance status
Systemic chemotherapy for gastric cancer is often associated with treatment-related toxicity, which is particularly severe in patients with a poor performance status. In this paper, we describe the first study to evaluate S-1 monotherapy as an option for advanced gastric cancer patients who are not candidates for combination chemotherapy due to poor clinical condition. Fifty-two patients with Eastern Cooperative Oncology Group (ECOG) performance scale 2–3, whose general condition had made use of combination chemotherapy impossible, were enrolled. S-1 was administered to 30 patients as second- or third-line therapy. The initial dose of S-1 was 35 mg m−2, administered b.i.d for 14 days every 3 weeks. With a median follow-up period of 33 weeks, the median progression-free survival, and overall survival were 11 weeks (95% CI, 8–14) and 33 weeks (95% CI, 19–47), respectively. The overall 1-year survival rate was 29% by intent-to-treat analysis. The overall response rate was 12% (95% CI, 3–21), and the percentage of stable disease was 35%, resulting in the disease control rate of 47% (95% CI, 32–60). Significant drug-related toxicity included grade 3 diarrhoea (14%), anorexia (14%), fatigue (10%), neutropenia (10%), and leucopenia (6%). In conclusion, this study indicated the modest activity of S-1 in gastric cancer patients with poor performance status
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Limit on suppression of ionization in metastable neon traps due to long-range anisotropy
This paper investigates the possibility of suppressing the ionization rate in
a magnetostatic trap of metastable neon atoms by spin-polarizing the atoms.
Suppression of the ionization is critical for the possibility of reaching
Bose-Einstein condensation with such atoms. We estimate the relevant long-range
interactions for the system, consisting of electric quadrupole-quadrupole and
dipole-induced dipole terms, and develop short-range potentials based on the
Na_2 singlet and triplet potentials. The auto-ionization widths of the system
are also calculated. With these ingredients we calculate the ionization rate
for spin-polarized and for spin-isotropic samples, caused by anisotropy of the
long-range interactions. We find that spin-polarization may allow for four
orders of magnitude suppression of the ionization rate for Ne. The results
depend sensitively on a precise knowledge of the interaction potentials,
however, pointing out the need for experimental input. The same model gives a
suppression ratio close to unity for metastable xenon in accordance with
experimental results, due to a much increased anisotropy in this case.Comment: 15 pages including figures, LaTex/RevTex, uses epsfig.st
Theoretical studies on space debris recycling and energy conversion system in the International Space Station
The space debris management and alleviation in the microgravity environment
is a dynamic research theme of contemporary interest. Herein, we provide a
theoretical proof of the concept of a lucrative energy conversion system that is
capable of changing the space debris into useful powders in the International
Space Station (ISS) for various bids. A specially designed broom is adapted to
collect the space debris of various sizes. An optical sorting method is proposed
for the debris segregation in the ISS by creating an artificial gravitational field.
It could be done by using the frame-dragging effect or gravitomagnetism. An
induction furnace is facilitated for converting the segregated metal-scrap into
liquid metal. A fuel-cell aided water atomization method is proposed for transforming the liquid debris into metal powder. The high-energetic metal powders
obtained from the space debris could be employed for producing propellants for
useful aerospace applications, and the silicon powder obtained could be used
for making soil for fostering the pharmaceutical-flora in the space lab in the
future aiming for the scarce-drug discoveries for high-endurance health care
management. The proposed energy conversion system is a possible alternative
for the space debris extenuation and its real applications in orbiting laboratories
through the international collaboration for the benefits to humanity
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