363 research outputs found
Pathogenesis of Abdominal Aortic Aneurysms: Role of Nicotine and Nicotinic Acetylcholine Receptors
Inflammation, proteolysis, smooth muscle cell apoptosis, and angiogenesis have been implicated in the pathogenesis of abdominal aortic aneurysms (AAAs), although the well-defined initiating mechanism is not fully understood. Matrix metalloproteinases (MMPs) such as MMP-2 and -9 and other proteinases degrading elastin and extracellular matrix are the critical pathogenesis of AAAs. Among the risk factors of AAAs, cigarette smoking is an irrefutable one. Cigarette smoke is practically involved in various aspects of the AAA pathogenesis. Nicotine, a major alkaloid in tobacco leaves and a primary component in cigarette smoke, can stimulate the MMPs expression by vascular SMCs, endothelial cells, and inflammatory cells in vascular wall and induce angiogenesis in the aneurysmal tissues. However, for the inflammatory and apoptotic processes in the pathogenesis of AAAs, nicotine seems to be moving in just the opposite direction. Additionally, the effects of nicotine are probably dose dependent or associated with the exposure duration and may be partly exerted by its receptors—nicotinic acetylcholine receptors (nAChRs). In this paper, we will mainly discuss the pathogenesis of AAAs involving inflammation, proteolysis, smooth muscle cell apoptosis and angiogenesis, and the roles of nicotine and nAChRs
Ecology and hydrology of early rice farming: geoarchaeological and palaeo-ecological evidence from the Late Holocene paddy field site at Maoshan, the Lower Yangtze
The well-preserved Maoshan paddy fields (4700–4300 bp) were built on an intermediate landscape between the foothills and alluvial plain of the Lower Yangtze River. Despite several interdisciplinary research, there has been a lack of detailed environmental and ecological data to contextualise the reconstructed rice farming practices within a wider paleo-environmental background. Our research provides key information on the chronology, vegetation, and long-term hydrological fluctuations at and surrounding the paddy fields. Our 14C and OSL dates show that the initial occupation began at around 5740 ± 140 cal. bp, and the paddy fields were built at around 4675 ± 145 cal. bp and were in use continuously until around 4000 cal. bp. Our pollen, diatom and phytolith data shows that whilst the vegetation in the field was sensitive to changes caused by water management and rice farming, the ecological system surrounding the fields was relatively stable. We suggest that this high frequency of in-field vegetation changes was closely related to intensifying water management for rice farming. This thesis is supported by our geophysical and geochemical analyses of bulk sediments, which shows that the steady build-up of the alluvial sequence was punctuated by several short-term episodes of high-energy surface runoff, including strong flushing in of sandy sediments into the fields perhaps through irrigation activities. Our paleo-ecological and geoarchaeological investigation at Maoshan permits an overview of the development of rice farming and intensifying water management practices in a wider environmental context and offers significant insights to the ongoing debate on the wet-dry dichotomy of early rice farming
Self-aligned, full solution process polymer field-effect transistor on flexible substrates
Conventional techniques to form selective surface energy regions on rigid inorganic substrates are not suitable for polymer interfaces due to sensitive and soft limitation of intrinsic polymer properties. Therefore, there is a strong demand for finding a novel and compatible method for polymeric surface energy modification. Here, by employing the confined photo-catalytic oxidation method, we successfully demonstrate full polymer filed-effect transistors fabricated through four-step spin-coating process on a flexible polymer substrate. The approach shows negligible etching effect on polymeric film. Even more, the insulating property of polymeric dielectric is not affected by the method, which is vital for polymer electronics. Finally, the self-aligned full polymer field-effect transistors on the flexible polymeric substrate are fabricated, showing good electrical properties and mechanical flexibility under bending tests
Obstructive sleep apnea affects lacrimal gland function
Purpose: To determine the effect of obstructive sleep apnea syndrome (OSA) on lacrimal gland function and its mechanism.
Methods: Male mice aged seven to eight weeks were housed in cages with cyclic intermittent hypoxia to mimic OSA, and the control group was kept in a normal environment. Slit-lamp observation, fluorescein staining, and corneal sensitivity detection are used to assess cornea changes. Tear secretion was detected by phenol red cotton thread, and the pathological changes of lacrimal gland were observed by hematoxylin and eosin staining, oil red O staining, cholesterol and triglyceride kits, immunofluorescence staining, immunohistochemical staining, real-time polymerase chain reaction, transmission electron microscopy, and Western blot.
Results: Studies revealed a decreased tear secretion, corneal epithelial defects and corneal hypersensitivity. Myoepithelial cell damage, abnormal lipid accumulation, reduced cell proliferation, increased apoptosis and inflammatory cell infiltration in the lacrimal gland were also seen. Hifα and NF-κB signaling pathways, moreover, were activated, while Pparα was downregulated, in the lacrimal glands of OSA mice. Fenofibrate treatment significantly alleviated pathological changes of the lacrimal gland induced by OSA.
Conclusion: OSA disturbs the Hifα/Pparα/NF-κB signaling axis, which affects lacrimal gland structure and function and induces dry eye
Chemical features of Ganoderma polysaccharides with antioxidant, antitumor and antimicrobial activities
Review aricleGanoderma genus comprises one of the most commonly studied species worldwide, G.
lucidum. However, other Ganoderma species have been also reported as important
sources of bioactive compounds. Polysaccharides are important contributors to the
medicinal properties reported for Ganoderma species, as demonstrated by the numerous
publications, including reviews, on this matter. Yet, what are the chemical features of
Ganoderma polysaccharides that have bioactivity? In the present manuscript, the
chemical features of Ganoderma polysaccharides with reported antioxidant, antitumor
and antimicrobial activities (the most studied worldwide) are analyzed in detail. The
composition of sugars (homo- versus hetero-glucans and other polysaccharides), type of
glycosidic linkages, branching patterns, and linkage to proteins are discussed. Methods
for extraction, isolation and identification are evaluated and, finally, the bioactivity of
polysaccharidic extracts and purified compounds are discussed. The integration of data
allows deduction of structure-activity relationships and gives clues to the chemical
aspects involved in Ganoderma bioactivity
Synthesis and catalysis of chemically reduced metal–metalloid amorphous alloys
This is the published version. Copyright 2012 Royal Society of ChemistryAmorphous alloys structurally deviate from crystalline materials in that they possess unique short-range ordered and long-range disordered atomic arrangement. They are important catalytic materials due to their unique chemical and structural properties including broadly adjustable composition, structural homogeneity, and high concentration of coordinatively unsaturated sites. As chemically reduced metal–metalloid amorphous alloys exhibit excellent catalytic performance in applications such as efficient chemical production, energy conversion, and environmental remediation, there is an intense surge in interest in using them as catalytic materials. This critical review summarizes the progress in the study of the metal–metalloid amorphous alloy catalysts, mainly in recent decades, with special focus on their synthetic strategies and catalytic applications in petrochemical, fine chemical, energy, and environmental relevant reactions. The review is intended to be a valuable resource to researchers interested in these exciting catalytic materials. We concluded the review with some perspectives on the challenges and opportunities about the future developments of metal–metalloid amorphous alloy catalysts
Relationships between athletic ability and academic performance in primary school students: A 3-year follow-up study
BackgroundThe aim of this study was to examine whether academic performance is associated with students' athletic ability in primary school.MethodsA 3-year follow-up study was conducted among 1,136 Chinese students. Sit-up and jump rope testers were used to measure 1-min sit-ups and 1-min jump ropes, respectively. Meanwhile, the Pittsburgh Sleep Quality Scale and the Beck Depression Inventory were used to estimate sleep quality and depression levels. The end-of-semester examinations were used to evaluate students' academic performance during the follow-up period.ResultsAfter adjusting for confounders, the mean change in Chinese language performance for participants stratified by 1-min sit-ups at baseline was 0.35 (95% CI: −0.37 to 0.76) for level 1 (slowest), 0.52 (95% CI: −0.54 to 1.08) for level 2, and 1.72 (95% CI: 1.14 to 2.30) for level 3 (fastest) (P for trend = 0.003); the mean change in math scores was 0.28 (95% CI: −0.50 to 0.95) for level 1 (slowest), 0.95 (95% CI: 0.38 to 1.52) for level 2, and 1.41 (95% CI: 0.82 to 1.99) for level 3 (fastest) (P for trend = 0.048). The mean change in foreign language scores was −0.45 (95% CI: −0.99 to −0.93) for level 1 (slowest), −0.14 (95% CI: −0.44 to 0.41) for level 2, and 0.69 (95% CI: 0.25 to 1.13) for level 3 (fastest) (P for trend = 0.004). The mean change in Chinese language performance for participants stratified by 1-min jump ropes at the baseline was 0.30 (95% CI: −0.16 to 0.76) for level 1 (slowest), 1.09 (95% CI: 0.42 to 1.76) for level 2, and 1.74 (95% CI: 1.14 to 2.35) for level 3 (fastest) (P for trend = 0.001). The mean change in math scores was 0.41 (95% CI: −0.11 to 0.92) for level 1 (slowest), 1.44 (95% CI: 0.69 to 2.19) for level 2, and 1.43 (95% CI: 0.76 to 2.10) for level 3 (fastest) (P for trend = 0.019). The mean change in foreign language performance was −0.71 (95% CI: −1.08 to −0.33) for level 1 (slowest), 0.95 (95% CI: −0.40 to 1.50) for level 2, and 0.91 (95% CI: 0.41 to 1.41) for level 3 (fastest) (P for trend < 0.001).ConclusionThis study suggests that participation in jump rope and sit-up exercises may positively affect students' academic performance
JUNO Conceptual Design Report
The Jiangmen Underground Neutrino Observatory (JUNO) is proposed to determine
the neutrino mass hierarchy using an underground liquid scintillator detector.
It is located 53 km away from both Yangjiang and Taishan Nuclear Power Plants
in Guangdong, China. The experimental hall, spanning more than 50 meters, is
under a granite mountain of over 700 m overburden. Within six years of running,
the detection of reactor antineutrinos can resolve the neutrino mass hierarchy
at a confidence level of 3-4, and determine neutrino oscillation
parameters , , and to
an accuracy of better than 1%. The JUNO detector can be also used to study
terrestrial and extra-terrestrial neutrinos and new physics beyond the Standard
Model. The central detector contains 20,000 tons liquid scintillator with an
acrylic sphere of 35 m in diameter. 17,000 508-mm diameter PMTs with high
quantum efficiency provide 75% optical coverage. The current choice of
the liquid scintillator is: linear alkyl benzene (LAB) as the solvent, plus PPO
as the scintillation fluor and a wavelength-shifter (Bis-MSB). The number of
detected photoelectrons per MeV is larger than 1,100 and the energy resolution
is expected to be 3% at 1 MeV. The calibration system is designed to deploy
multiple sources to cover the entire energy range of reactor antineutrinos, and
to achieve a full-volume position coverage inside the detector. The veto system
is used for muon detection, muon induced background study and reduction. It
consists of a Water Cherenkov detector and a Top Tracker system. The readout
system, the detector control system and the offline system insure efficient and
stable data acquisition and processing.Comment: 328 pages, 211 figure
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