Polyamines, small aliphatic polycations, have been suggested to play key roles in a number of biological processes. In this paper, attempts were made to investigate the possibility of improving ...dehydration tolerance of citrus in vitro plants by exogenous application of spermine (Spm). ‘Red Tangerine’ (Citrus reticulata Blanco) in vitro plants pretreated with 1 mM Spm exhibited less wilted phenotype and lower water loss and electrolyte leakage than the control under dehydration. Spm-pretreated plants contained higher endogenous polyamine content during the course of the experiment relative to the control, particularly at the end of dehydration, coupled with higher expression levels of ADC and SPMS. Histochemical staining showed that the Spm-pretreated leaves were stained to a lower extent than those without Spm pretreatment, implying generation of less reactive oxygen species (ROS). On the contrary, activities of peroxidase (POD) and superoxide dismutase (SOD) in the Spm-pretreated samples were higher than the control at a given time point or during the whole experiment, suggesting that Spm exerted a positive effect on antioxidant systems. In addition, significantly smaller stomatal aperture size was observed in Spm-pretreated epidermal peels, which showed that stomatal closure was promoted by polyamines. All of these data suggest that Spm pretreatment causes accumulation of higher endogenous polyamines and accordingly leads to more effective ROS scavenging (less tissue damage) and stimulated stomatal closure (lower water loss) upon dehydration, which may function collectively to enhance dehydration tolerance.
Abstract
Mechanical sensitivities (such as friction and impact sensitivity) are the most important evaluation index to characterize the risk of energetic materials (EMs), as they are the most common ...stimulus during preparation, transportation and usage of EMs. Recently, carbon nanomaterials (CNMs) have been found to be effective in reducing mechanical sensitivities of EMs with small amount of addition. This review covers updated researches of the desensitization of EMs by using fullerenes, expanded graphite (EG), carbon nanotubes (CNTs), graphene and graphene oxide (GO), their desensitization results and relative mechanisms are summarized. It has been shown that graphene and its derivatives are more effective due to their superior thermal conductivity and layered structure.
We report the fabrication and characterization of ZnO nanowire memory devices using a ferroelectric Pb(Zr0.3Ti0.7)O3 (PZT) film as the gate dielectric and the charge storage medium. With a comparison ...to nanowire transistors based on SiO2 gate oxide, the devices were evaluated in terms of their electric transport, retention, and endurance performance. Memory effects are observed as characterized by an eminent counterclockwise loop in I−V g curves, which is attributed to the switchable remnant polarization of PZT. The single-nanowire device exhibits a high (up to 103) on/off ratio at zero gate voltage. Our results give a proof-of-principle demonstration of the memory application based on a combination of nanowires (as channels) and ferroelectric films (as gate oxide).
It has been generally acknowledged that the diagnosis, treatment and prognosis evaluation of leukemia largely rely on an adequate identification of genetic abnormalities. A systemic analysis of ...genetic aberrations was performed in a cohort of 1346 patients with newly diagnosed acute lymphoblastic leukemia (ALL) in China. The pediatric patients had higher incidence of hyperdiploidy and t(12;21) (p13;q22)/ETV6-RUNX1 than adults (P<0.0001); in contrast, the occurrence of Ph and Ik6 variant of IKZF1 gene was much more frequent in adult patients (all P<0.0001). In B-ALL, the existence of Ik6 and that of BCR-ABL were statistically correlated (P<0.0001). In comparison with Western cohorts, the incidence of t(9;22) (q34;q11)/BCR-ABL (14.60%) in B-ALL and HOX11 expression in T-ALL (25.24%) seemed to be much higher in our group, while the incidence of t(12;21) (p13;q22)/ETV6-RUNX1 (15.34%) seemed to be lower in Chinese pediatric patients. The occurrence of hyperdiploidy was much lower either in pediatric (10.61% vs 20-38%) or adult patients (2.36% vs 6.77-12%) in our study than in Western reports. In addition, the frequencies of HOX11L2 in adult patients were much higher in our cohort than in Western countries (20.69% vs 4-11%). In general, it seems that Chinese ALL patients bear more adverse prognostic factors than their Western counterparts do.
Single-crystal tetragonal α-MnO2 nanotubes have been successfully synthesized by a facile hydrothermal treatment of KMnO4 in the hydrochloric acid solution. The sample has been characterized by X-ray ...powder diffraction, field emission scanning electron microscopy, transmission electron microscopy, and orientation dependent Raman spectroscopy, which indicates the nanotubes have high-quality crystalline and shape-dependent optical properties. The morphology evolution of the sample reveals that the nanotubes are formed via the solid nanorod by a chemical etching process.
Reinforcement agglomeration always leads to severe stress concentration and porosity, which is detrimental to the deformation ability and mechanical properties of particulate-reinforced metal matrix ...composites. In this study, uniform distribution of 32vol%B4C has been achieved in B4C/Al composite by means of flake powder metallurgy (Flake PM), in which flake Al powder is used as the starting material. The flake Al powder exhibits higher apparent volume than spherical powders of the same mass, and thus can provide more space to accommodate the B4C particles. Therefore, compared with conventional PM, Flake PM can lead to more uniform distribution of B4C particles in the composite powder as well as in the consolidated composite. Meanwhile, the flake Al powder has a nano skin of Al2O3, which could be fractured and dispersed inside the fine matrix grains during consolidation, and were found to induce a higher normalized strain hardening rate for the composite during deformation. As a result, the Flake PM 32vol%B4C/Al composite exhibits an ultimate tensile strength of 305MPa and a uniform elongation of 6.6%, 63% stronger and 13% more ductile than its counterpart fabricated by conventional PM.
This study investigated the effects of dietary Arginine (Arg) on performance, intestinal antioxidative capacity, immunity, and gut microbiota in Chinese yellow-feathered chickens. One thousand two ...hundred 1-day-old female Qingyuan partridge chickens were randomly assigned to 5 groups with 6 replicates of 40 birds each. Chickens were fed diets with 5 levels of total Arg (8.5, 9.7, 10.9, 12.1, and 13.3 g/kg) without antibiotics for 30 d. The ADFI, ADG, and feed conversion ratio were improved with dietary Arg levels (P < 0.05). The proportions of CD3+ and CD4+/CD8+ lymphocytes responded in a linear (P < 0.05) manner and those of CD4+ in a linear or quadratic (P < 0.05) manner as dietary Arg levels increased. Dietary Arg level had a linear (P < 0.05) or quadratic (P < 0.05) effect on the gene expression of glutathione peroxidase 1, heme oxygenase 1, nuclear factor erythroid 2–related factor 2, and the activities of glutathione peroxidase and total antioxidative capacity in the jejunum and ileum. The relative expression of IL-1β, myeloid differentiation primary response 88, and Toll-like receptor 4 decreased linearly (P < 0.05) in the ileum with increasing dietary Arg levels; secretory IgA contents were increased. In addition, sequencing data of 16S rRNA indicated that dietary Arg increased the relative abundance of Firmicutes phylum, Romboutsia and Candidatus Arthromitus genera, while decreased that of Clostridium sensu stricto 1. A diet containing 12.1 g Arg/kg promoted growth performance, intestinal antioxidation, and innate immunity and modulated gut microbiota in yellow-feathered chickens.
Abstract
In this paper, the damage effectiveness of a single projectile of small caliber (30-35 mm) anti-aircraft gun under multi-error constraints is studied. Based on the known prior information of ...target motion and the dispersion mathematical model of prefabricated fragment warhead, under the constraints of fragment effective killing radius and target equivalent size, the fuze starting characteristic factor is introduced to establish the integrated model of fuze and warhead. Based on the Monte-Carlo method, the variation law of the damage effectiveness of a single projectile under the joint constraints of the gun firing angle error and the fuze fixed range error is analyzed. The simulated annealing (SA) algorithm is used to find the global optimal solution of the model. The optimal damage effectiveness of a single projectile under multi-error constraints is found. The results show that the damage effectiveness of single projectile is increased by 26.91% without changing the state of existing weapon and equipment.
Stratigraphical and chronological investigations of four sediment cores from Bosten Lake, the largest inland freshwater lake in China, provide a reliable regional environmental evolution record since ...the late-glacial. The stratigraphy of the four cores has been well correlated according to their lithology and chronology (OSL and
14C dates). Pollen and grain size data from Bosten Lake show evidence for a dry regional climate during late-glacial and early Holocene (16–8
cal
ka
BP) indicated by a thick layer of aeolian sand deposit (>100
cm). Although the climate became humid after 8
cal
ka
BP, analysis of pollen assemblages (pollen A/C ratio and
Ephedra percentage) also indicates that the climate was relatively dry in the Bosten Lake area between 8 and 6
cal
ka
BP, while afterwards more humid conditions (ca 6–1.5
cal
ka
BP) are assumed. Comparison with other lake records from arid central Asia influenced by the westerly winds generally supports the assumption of late-glacial to early Holocene dry climates in westerly dominated regions. Hence, they contrast the Holocene climate development in monsoon Asia. Relatively wet conditions during the late Holocene (6–1.5
cal
ka
BP) might be induced by stronger westerly circulation.
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