To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Interactions of fluvial and eolian processes are prominent in dryland environments and can significantly change Earth surface morphology. Here, we report on sediment records of eolian and fluvial interactions since the last glacial period, in the semiarid area of northwest China, at the limit of the Southeast Asian monsoon. Sediment sequences of last glacial and Holocene terraces of the Yellow River are composed of channel gravels, overlain by flood sands, eolian dunes, and flood loams. These sequences, dated by optically stimulated luminescence, record interlinks between fluvial and eolian processes and their response to climate change. Sedimentologic structures and grain-size analysis show flood loams, consisting of windblown sediment, deposited from floodwater suspended sediment. The gravel and sand were deposited during cold periods. During transitions from cold to warm phases, the river incised, and dunes were formed by deflation of channel and floodplain deposits (>70 and 21–16 ka). Dunes also formed at ~0.8 ka, probably after human intervention. After dune formation, flood loam covered dunes without erosion during peak discharges at the beginning of the subsequent warm period. The fluctuations of the Southeast Asian monsoon as a moisture-transporting agent have perhaps been the driving force for interactions between fluvial and eolian processes in this semiarid environment.
Accumulating evidence suggests that altered immunity contributes to the
development of major depressive disorder (MDD).
To examine whether complement factor H (CFH), a regulator of activation
of the alternative pathway of the complement cascade, confers
susceptibility to MDD.
Expression analyses were tested in 53 unmedicated people with MDD and 55
healthy controls. A two-stage genetic association analysis was performed
in 3323 Han Chinese with or without MDD. Potential associations between
CFH single nucleotide polymorphisms and age at MDD
onset were evaluated.
CFH levels were significantly lower in the MDD group at
both protein and mRNA levels (P = 0.009 and
P = 0.014 respectively). A regulatory variant in the
CFH gene, rs1061170, showed statistically significant
genotypic and allelic differences between the MDD and control groups
(genotypic P = 0.0005, allelic P =
0.0001). Kaplan–Meier survival analysis showed that age at onset of MDD
was significantly associated with the C allele of
rs1061170 (log rank statistic χ2 = 6.82, P =
0.009). The C-allele carriers had a younger age at onset
of MDD (22.2 years, s.d. = 4.0) than those without the C
allele (23.6 years, s.d. = 4.3).
CFH is likely to play an important role in the
development of MDD. rs1061170 has an important effect on age at onset of
MDD in Han Chinese and may therefore be related to early pathogenesis of
MDD, although further study is needed.
Given a smooth minimal surface F: Ω → ℝ3 defined on a simply connected region Ω in the complex plane ℂ, there is a regular SG circle pattern . By the Weierstrass representation of F and the existence theorem of SG circle patterns, there exists an associated SG circle pattern in ℂ with the combinatoric of . Based on the relationship between the circle pattern and the corresponding discrete minimal surface F∊: → ℝ3 defined on the vertex set of the graph of , we show that there exists a family of discrete minimal surface Γ∊: → ℝ3, which converges in C∞(Ω) to the minimal surface F: Ω → ℝ3 as ∊ → 0.
A novel hybrid robotic arm with three fingers is proposed for assembly, operation and rescue. It is composed of an upper 3RPS-type parallel manipulator, a lower 3SPR-type parallel manipulator and three fingers. Its dynamics are studied and analyzed systematically. First, the kinematics formulae of the moving links at their mass centers in the hybrid robotic arm with three fingers are established. Second, the formulae for solving the inertial wrench of the moving links at their mass centers are derived. Third, a dynamics formula is established for solving the dynamic active/constrained forces of the hybrid robotic arm and the fingers. Finally, an analytic example is given for solving the kinematics and dynamics of the hybrid robotic arm with three fingers and the analytic solved solutions are verified by a simulation mechanism.
Low-temperature stress is an important limiting factor to tobacco growth in early spring of south China. In this study, a low-temperature-resistant agent (LTRA) was employed to examine its ameliorating effect on the inhibition of tobacco growth triggered by low-temperature stress. Results indicated that low-temperature stress of 12 °C for 6 days reduced root number and biomass of tobacco seedling by 27.4% and 24.1%, while treatment with LTRA could recover the inhibitory effect of low-temperature stress on tobacco growth significantly. The content of ascorbic acid and the activities of superoxide dismutase and catalase at low-temperature stress were 65.2%, 53.5% and 32.1% of those at normal temperature condition (26 °C), while the corresponding values with LTRA treatment were 89.2%, 88.9% and 74.2%, suggesting that LTRA treatment could enhance the activity of antioxidant enzyme and the synthesis of antioxidant compounds. Low-temperature stress increased the membrane permeability by 84.8%, while LTRA treatment recovered it by 77.4%. Furthermore, LTRA treatment contributed to increase chlorophyll synthesis and maintain the integrity of tobacco leaf structure. Effective component analysis indicated that the complex of ammonium calcium nitrate and glycine betaine was the main effective component of LTRA in maintaining membrane integrity. Its effective concentration was 1.0 g L−1. The above results suggested that LTRA could enhance the synthesis of chlorophyll, activate the activity of antioxidant enzyme, maintain the integrity of cell membrane, and thus elevate the tolerance of tobacco seedlings to low-temperature stress.
A broadband omnidirectional absorber which is realized by heterostructures containing a collision plasma layer and a zero − n̅ mirror is theoretically investigated. A collision plasma layer and an appropriate dielectric layer are put on the top of the PC. It is shown to absorb roughly 70% of all available electromagnetic wave in a relative omnidirectional absorption band width 244 MHz. The absorption band edge of the PC is influenced by the range of the reflection band gap. Meanwhile, the absorption range for the transverse magnetic (TM) wave decreases at large incident angle. Compared with some previous designs, our proposed structure has a relative flatter total absorption spectrum over a broad microwave frequency range and using a zero − n̅ gap as a mirror is insensitive to the incident angle. This kind of heterostructure offers additional opportunities to design novel optoelectronic devices.
Our previous study demonstrated that 60 % ethanol crude extract of Sambucus williamsii HANCE (SWH) improved bone mass, bone strength and bone micro-structure in both ovariectomised (OVX) rats and mice. The present study aims to identify the bioactive fractions and ingredients in SWH that account for its osteoprotective effects. Bilateral sham-operated mice acted as controls. OVX C57BL/6J mice, aged 12 weeks, were orally administrated daily with vehicle or 17β-oestradiol (3·2 mg/kg), SWH (60 % ethanol crude extract; 1·0 g/kg), SWA (water eluate; 0·570 g/kg), SWB (30 % ethanol eluate; 0·128 g/kg) or SWC (50 and 95 % ethanol eluates; 0·189 g/kg) for 12 weeks. The effects of the different fractions on bone properties in the OVX mice model were studied. In addition, their effects on osteoblast proliferation and differentiation were evaluated in UMR 106 cells. SWC significantly restored bone mineral density and improved bone size and bone content parameters in the femur and tibia as well as increased biomechanical strength at the tibia diaphysis in OVX mice. Similarly, SWC was the most potent fraction in stimulating cell proliferation and differentiation in UMR 106 cells. Also, SWC did not alter uterus weight in OVX mice. Nine major peaks, seven lignans and two phenolic acids, in the HPLC fingerprint of the SWC fraction were identified, isolated and characterised. In conclusion, the present study demonstrated that SWC was the most potent fraction in SWH that exerted anti-osteoporotic effects. Furthermore, lignans might be the potential bioactive components in SWC.
High-Tc superconducting epitaxial thin films of gadolinium barium copper oxide,grown in situ by dc-magnetron sputtering onto substrates of single crystal (001) orientated LaAIO3 , SrTiO3 and yttrium stabilisedZrO2 have been studied by high resolution double axis difffactometry, X-ray white beam-Laue topography and double crystal topography. Rocking curve halfwidths were found to vary from about 1000 to 3000 arc seconds, very good in thecontext of these complex materials. The topographs showed that the orientations of the small crystallites was randomly distributed across the sample.
Unintentionally doped n-type ZnO single crystals were implanted by nitrogen ions with different fluences of 1013, 1014 and 1015 cm−2 respectively. ZnO p-n homojunction was successfully fabricated due to the formation of p-type layer after 650°C post-implantation annealing in air for 30 minutes. Further thermal evolution of deep level defects was studied through thermal annealing up to 1200°C. Electrical characterization techniques including current-voltage (I-V), capacitance-voltage (C-V), Deep Level Transient Spectroscopy (DLTS) and double-correlation DLTS (DDLTS) were used for investigating the control sample, all the as-implanted and annealed samples through Au/n-ZnO Schottky diodes as well as ZnO p-n junctions. Detailed electrical properties of fabricated devices and characteristics of implantation induced defects were analyzed based on plentiful DLTS spectra. Moreover, low-temperature photoluminescence experiments of all the as-implanted and annealed samples were performed and the correlation between results from electrical and optical characterizations was discussed.
In the preparation of zeolite nanocrystals from the hydrothermal reaction of clear solution, the zeolite products are typically collected by high speed centrifugation. For Beta zeolite, the crystalline yield is often low, thus a good fraction of silicates reminds in the supernatant. These XRD amorphous materials turn out to be uniform nanoparticles that, after calcination, showed similar micropore structure as that of the collected beta zeolite nanocrystals. TPD measurements of hexane isomers further indicated that both the crystalline and the amorphous products were more selective toward the smaller hexane molecule.
Amplified fragment length polymorphism (AFLP) markers linked to the stem nematode resistance gene were developed in sweet potato (Ipomoea batatas (L.) Lam.). Using bulked segregant analysis (BSA), 800 AFLP primer combinations were screened in the resistant and susceptible bulked DNA from the 186 progeny of an F1 single-cross population of Xu781 (resistant parent)×Xushu18 (susceptible parent), and 245 of these AFLP primers showed polymorphic bands between resistant and susceptible DNA. Primer combinations detecting polymorphism between the two bulks were used to screen the parents and eight individuals from each of the bulks. The results showed that E2M23 and E33M20 produced a specific band of about 500 bp and 200 bp in length, respectively, in the resistant plants but not in the susceptible plants, suggesting that the markers named E2M23500 and E33M20200 linked to a gene for stem nematode resistance. Amplified analysis of the 186 F1 individuals indicated that the genetic distance between these two markers and the stem nematode resistance gene was 6.9 cM and 11.1 cM, respectively, measured with Mapmaker 3.0. These two AFLP markers were used to identify ten sweet potato varieties planted widely in China and the results were consistent with those of conventional resistance identification, indicating that the two markers can be used in molecular marker-assisted breeding for stem nematode resistance in the sweet potato.
The RNA-dependent RNA polymerase (RdRp) gene of Bombyx mori cypovirus 1 (BmCPV-1) (China strain) was cloned in three fragments using step-by-step reverse transcriptase-polymerase chain reaction (RT-PCR). The whole RdRp gene of 3691 bp was sequenced (GenBank accession number: AY496445). Vector pET-28b(+) was used to construct the expression vector pET28b–RdRp which was expressed in Escherichia coli BL21 (DE3) induced with isopropyl β-d-thiogalactoside (IPTG). The molecular weight of the expression product was about 138 Da. The primary antibody employed was rabbit antibody against BmCPV–RdRp recombinant protein and the secondary antibody was 15 nm immunogold-labelled goat anti-rabbit IgG. Immunogold was mostly bound to the virions which were dispersed in a virus generation matrix and polyhedron in the columnar cells of the midgut of the silkworms, and the average marking ratio was about 35%. This result demonstrated that BmCPV–RdRp complexes are indeed located at the BmCPV capsid.
Email your librarian or administrator to recommend adding this to your organisation's collection.