Generation of subcycle isolated attosecond pulses by pumping ionizing gating

We present a novel approach named as pumping ionizing gating (PIG) for the generation of isolated attosecond pulses (IAPs). In this regime, a short laser is used to ionize a pre-existing gas grating, creating a fast-extending plasma grating(FEPG) having an ionization front propagating with the velocity of light. A low-intensity long counterpropagating pump pulse is then reflected by a very narrow region of the ionization front, only where the Bragg conditions for resonant reflection is satisfied. Consequently, the pump reflection is confined within a sub-cycle region called PIG, and forms a wide-band coherent IAP in combination with the frequency up-conversion effect due to the plasma gradient. This approach results in a new scheme to generate IAPs fromlong picosecond pump pulses. Three-dimensional (3D) simulations show that a 1.6-ps, 1-{\mu}m pump pulse can be used to generate a 330 as laser pulse with a peak intensity approximately 33 times that of the pump and a conversion efficiency of around 0.1%.These results highlight the potential of the PIG method for generating IAPs with high conversion efficiency and peak intensity.Comment: It provides a new way to generate isolated attosecond pulse(IAP) by a picosecond pump, which has a protential to boost the IAP energy to joule leve

Measurement of forward charged hadron flow harmonics in peripheral PbPb collisions at √sNN = 5.02 TeV with the LHCb detector

Flow harmonic coefficients, v n , which are the key to studying the hydrodynamics of the quark-gluon plasma (QGP) created in heavy-ion collisions, have been measured in various collision systems and kinematic regions and using various particle species. The study of flow harmonics in a wide pseudorapidity range is particularly valuable to understand the temperature dependence of the shear viscosity to entropy density ratio of the QGP. This paper presents the first LHCb results of the second- and the third-order flow harmonic coefficients of charged hadrons as a function of transverse momentum in the forward region, corresponding to pseudorapidities between 2.0 and 4.9, using the data collected from PbPb collisions in 2018 at a center-of-mass energy of 5.02 TeV . The coefficients measured using the two-particle angular correlation analysis method are smaller than the central-pseudorapidity measurements at ALICE and ATLAS from the same collision system but share similar features

Low-Density and High-Performance Fiber-Reinforced PP/POE Composite Foam via Irradiation Crosslinking

This study addresses the challenge of achieving foam with a high expansion ratio and poor mechanical properties, caused by the low melt viscosity of semi-crystalline polypropylene (PP). We systematically employ a modification approach involving blending PP with polyolefin elastomers (POE), irradiation crosslinking, and fiber reinforcement to prepare fiber-reinforced crosslinked PP/POE composite foam. Through optimization and characterization of material composition and processing conditions, the obtained fiber-reinforced crosslinked PP/POE composite foam exhibits both low density and high performance. Specifically, at a crosslinking degree of 12%, the expansion ratio reaches 16 times its original value, and a foam density of 0.057 g/cm3 is reduced by 36% compared to the non-crosslinked PP/POE system with a density of 0.089 g/cm3. The density of the short-carbon-fiber-reinforced crosslinked sCF/PP/POE composite foam is comparable to that of the crosslinked PP/POE system, but the tensile strength reaches 0.69 MPa, representing a 200% increase over the crosslinked PP/POE system and a 41% increase over the non-crosslinked PP/POE system. Simultaneously, it exhibits excellent impact strength, tear resistance, and low heat shrinkage. Irradiation crosslinking is beneficial for enhancing the melt strength and resistance to high temperature thermal shrinkage of PP/POE foam, while fiber reinforcement contributes significantly to improving mechanical properties. These achieve a good complementary effect in low-density and high-performance PP foam modification

APP-C31 Is an Intracellular Promoter of Amyloid-Beta Aggregation and Toxicity

Intracellular C-terminal cleavage of the amyloid precursor protein (APP) is elevated in the brain of Alzheimer’s disease (AD). Emerging evidence proposes a pathological relationship between the production of a C-terminal APP fragment, called APP-C31, and the toxicity induced by amyloid-beta (Abeta) that is a major contributor towards AD; however, the interaction between the two peptides and the consequent impact of APP-C31 on Abeta-related toxicity were unknown thus far. Here we report the discovery that APP-C31 facilitates the aggregation of Abeta and aggravates its toxicity at the intracellular level, with escalating neurodegeneration. APP-C31 forms a hetero-dimer with Abeta through the contacts onto the N-terminal and self-recognition regions of Abeta and induces its conformational transition accelerating amyloid fibrillization. APP-C31 promotes the perinuclear and intranuclear deposition of enlarged Abeta aggregates and, consequently, damages the nucleus leading to apoptosis. Abeta-induced degeneration of neurites in human neurons is also intensified by APP-C31. Our studies demonstrate a new function of APP-C31 as an intracellular factor of the proteopathy found in AD.</p

A Temperature-Dependent Model for Tritrophic Interactions Involving Tea Plants, Tea Green Leafhoppers and Natural Enemies

The tea green leaf hopper, Empoasca onukii Matsuda, is a severe pest of tea plants. Volatile emissions from tea shoots infested by the tea green leafhopper may directly repel insect feeding or attract natural enemies. Many studies have been conducted on various aspects of the tritrophic relationship involving tea plants, tea green leafhoppers and natural enemies. However, mathematic models which could explain the dynamic mechanisms of this tritrophic interaction are still lacking. In the current work, we constructed a realistic and stochastic model with temperature-dependent features to characterize the tritrophic interactions in the tea agroecosystem. Model outputs showed that two leafhopper outbreaks occur in a year, with their features being consistent with field observations. Simulations showed that daily average effective accumulated temperature (EAT) might be an important metric for outbreak prediction. We also showed that application of slow-releasing semiochemicals, as either repellents or attractants, may be highly efficacious for pest biocontrol and can significantly increase tea yields. Furthermore, the start date of applying semiochemicals can be optimized to effectively increase tea yields. The current model qualitatively characterizes key features of the tritrophic interactions and provides critical insight into pest control in tea ecosystems

Cytochrome c as a distinct modulator of amyloid-beta amyloidogenesis in a peroxide-dependent manner

Cytochrome c (Cyt c) is an important, multifunctional protein for controlling cell fate. Emerging evidence suggests a potential role of Cyt c in the amyloid pathology associated with Alzheimer’s disease (AD); however, the interaction between Cyt c and Abeta with the consequent impact on the aggregation and toxicity of Abeta is not known. Here we report the discovery that Cyt c can directly bind to Abeta and alter the aggregation and toxicity profiles of Abeta in a peroxide-dependent manner. Cyt c redirects Abeta peptides into less toxic, off-pathway amorphous aggregates in the presence of hydrogen peroxide (H2O2), whereas it accelerates Abeta fibrillization without H2O2. Such effects can be achieved by three possible mechanisms, including the complexation between Cyt c and Abeta, the oxidation of Abeta by Cyt c and H2O2, and the H2O2-mediated modification of Cyt c. Our studies demonstrate a new function of Cyt c as a modulator against Abeta amyloidogenesis

Unveiling the impact of oxidation-driven endogenous protein interactions on the dynamics of amyloid-beta aggregation and toxicity

Cytochrome c (Cyt c), a multifunctional protein with a crucial role in controlling cell fate, has been implicated in the amyloid pathology associated with Alzheimer&apos;s disease (AD); however, the interaction between Cyt c and amyloid-beta (A beta) with the consequent impact on the aggregation and toxicity of A beta is not known. Here we report that Cyt c can directly bind to A beta and alter the aggregation and toxicity profiles of A beta in a manner that is dependent on the presence of a peroxide. When combined with hydrogen peroxide (H2O2), Cyt c redirects A beta peptides into less toxic, off-pathway amorphous aggregates, whereas without H2O2, it promotes A beta fibrillization. The mechanisms behind these effects may involve a combination of the complexation between Cyt c and A beta, the oxidation of A beta by Cyt c and H2O2, and the modification of Cyt c by H2O2. Our findings demonstrate a new function of Cyt c as a modulator against A beta amyloidogenesis.11Nsciescopu

Generation of subcycle isolated attosecond pulses by pumping ionizing gating

We present an interesting approach named as pumping ionizing gating (PIG) for the generation of isolated attosecond pulses (IAPs). In this regime, a short laser is used to ionize a preexisting gas grating, creating a fast-extending plasma grating (FEPG) having an ionization front propagating with the velocity of light. A low-intensity long counterpropagating pump pulse is then reflected by a very narrow region of the ionization front, only where the Bragg conditions for resonant reflection is satisfied. Consequently, the pump reflection is confined within a subcycle region called PIG, and forms a wide-band coherent IAP in combination with the frequency up-conversion effect due to the plasma gradient. This approach results in a new scheme to generate IAPs from long picosecond pump pulses. Three-dimensional (3D) simulations show that a 1.6 ps, 1 µm pump pulse can be used to generate a 330 as laser pulse with a peak intensity approximately 33 times that of the pump and a conversion efficiency of around 0.1%. These results highlight the potential of the PIG method for generating IAPs with high conversion efficiency and peak intensity

APP‐C31: An Intracellular Promoter of Both Metal‐Free and Metal‐Bound Amyloid‐β40 Aggregation and Toxicity in Alzheimer's Disease

Abstract Intracellular C‐terminal cleavage of the amyloid precursor protein (APP) is elevated in the brains of Alzheimer's disease (AD) patients and produces a peptide labeled APP‐C31 that is suspected to be involved in the pathology of AD. But details about the role of APP‐C31 in the development of the disease are not known. Here, this work reports that APP‐C31 directly interacts with the N‐terminal and self‐recognition regions of amyloid‐β40 (Aβ40) to form transient adducts, which facilitates the aggregation of both metal‐free and metal‐bound Aβ40 peptides and aggravates their toxicity. Specifically, APP‐C31 increases the perinuclear and intranuclear generation of large Aβ40 deposits and, consequently, damages the nucleus leading to apoptosis. The Aβ40‐induced degeneration of neurites and inflammation are also intensified by APP‐C31 in human neurons and murine brains. This study demonstrates a new function of APP‐C31 as an intracellular promoter of Aβ40 amyloidogenesis in both metal‐free and metal‐present environments, and may offer an interesting alternative target for developing treatments for AD that have not been considered thus far