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.
We develop a general method for constructing knotted flux tubes with finite thickness, arbitrary shape and tunable twist. The central axis of the knotted tube is specified by a smooth and non-degenerate parametric equation. The helicity of the corresponding solenoidal knotted field can be explicitly decomposed into writhe, normalized total torsion and intrinsic twist. We construct several knotted magnetic flux tubes with various twisting degrees, and investigate the effect of twist on their evolution in resistive magnetohydrodynamic flows using direct numerical simulation. For large twist, the magnetic knot gradually shrinks to a tight stable state, similar to the relaxation process in ideal magnetohydrodynamic flows. For small twist, the knotted flux tube splits at early times, accompanied by a rising magnetic dissipation rate. We elucidate the mechanism of the tube splitting using the phase portrait of the Lorentz force projected onto divergence-free space. For finite twist, the Hopf bifurcation from an unstable spiral point to a limit cycle occurs on the phase plane. In the evolution, field lines inside the limit cycle form invariant tori, whereas they become chaotic outside the limit cycle.
As electrode materials, metal-organic frameworks always have low electrical conductivity and poor structural stability, which limits its applications in electrochemical fields. Here, Ni-BPDC/GO composites are synthesized using graphene oxide (GO) as a substrate and 4,4′-biphenyldicarboxylic acid (BPDC) as an organic ligand via a hydrothermal approach. The growth mechanism of the Ni-BPDC and Ni-BPDC/GO composites is proposed. In the composites, highly dispersed Ni-BPDC macro-nanostrips are supported on the GO surface in parallel. The presence of GO does not affect the growth and crystalline structure of Ni-BPDC. Compared with the Ni-BPDC, Ni-BPDC/GO composites exhibit higher specific capacitance, rate capability, and operating current density through lowering intrinsic resistance, charge-transfer resistance, and ion diffusion impedance. Moreover, the assembled Ni-BPDC/GO-3//reduced graphene oxide (rGO) asymmetric supercapacitor has large specific capacitance, good cycling stability, and high energy density (16.5 W h/kg at 250 W/kg). Hence, Ni-BPDC/GO composites are a potential electrode material for supercapacitors.
The Gangdese magmatic belt across the southern Tibetan Plateau is juxtaposed with the Indus–Yurlung Zangbo suture zone (IYS), and many mafic microgranular enclaves (MMEs) are exposed in the belt, thus providing a window for observing deep crust–mantle processes related to the Indo-Asian collision. The Nyemo intrusion is located in the middle part of the Gangdese magmatic belt and comprises host diorites with abundant MMEs. Compared with other parts of the Gangdese magmatic belt, the host rock of the Nyemo intrusion has a mineral composition similar to that of the MME, although differences are observed in chemical contents. To explore the genetic type of the MMEs and the deep processes of the Gangdese magmatic belt, the Nyemo intrusion is selected as the research object for this paper. Here, we report zircon U–Pb geochronological and whole-rock geochemical data for host diorites and MMEs, and electron probe data for hornblendes in diorites and MMEs, and combine mineralogy, petrology, petrogeochemistry and isotope geochemistry analyses. Research has shown that diorites in the Nyemo intrusion belong to the medium-K, metaluminous series. The light rare earth elements (LREEs) and heavy rare earth elements (HREEs) are significantly fractionated, and the LREE/HREE values are 5.77–7.71. The (87Sr/86Sr)i values of the diorites range from 0.704260 to 0.704287, and the εNd(t) values are from 3.73 to 4.17. The MMEs in the Nyemo intrusion have a limited range of SiO2 contents, are calc-alkaline with metaluminous affinity, and have relatively high contents of MgO (4.34–5.00 wt %) with Mg# (Mg2+/Mg2+ + Fe2+) values of 42.36–43.53, which is close to that of evolved basic magma. The contents of REEs vary from 108.87 to 120.59 ppm and show obvious Eu anomalies. The (87Sr/86Sr)i values of the MMEs range from 0.704680 to 0.704704, and the εNd(t) values are 0.35–3.74. The crystallization temperature of the hornblende in the diorite is 820 °C, the formation depth is 5.39 km, the oxygen fugacity is ΔNNO + 0.88 and the water content is 5.95 %. The crystallization temperature of the hornblende in the MMEs is 880 °C, the formation depth is 12.18 km, the oxygen fugacity is ΔNNO + 0.38 and the water content is 8.27 %. The Nyemo MMEs are formed by magma mingling, and originate from the partial melting of the depleted mantle, while the host diorite originates from partial melting of the juvenile crust with the addition of mantle material. The formation of the Gangdese magmatic belt is related to the Indo-Asian continental collision. The break-off of the subducted Neo-Tethyan oceanic plate triggered partial melting of the asthenosphere, which resulted in accumulation of the basaltic magma and then caused the partial melting of the juvenile crust with the addition of mantle material, thus forming a variety of granitic rocks and the large Gangdese magmatic belt.
Organic light-emitting diodes (OLEDs) have aroused great attention due to the advantages of high luminescent efficiency, fast response time, wide viewing angle, and the compatibility with the flexible electronics. Nevertheless, the organic luminescent materials are vulnerable to environment moisture/oxygen. Thus, how to protect the OLEDs from the ambient moisture/oxygen erosion is of great importance to ensure the stability and reliability. Thin film encapsulation (TFE) via atomic layer deposition (ALD) has emerged as a potential method to meet the encapsulation requirements of OLEDs due to its unique assets. In this review, the challenges of TFE, including pinholes, crystallization, cracks, and overheated, are introduced first. The ALD-based monolayer, composite structures, and hybrid laminates were developed to improve the barrier property, flexibility, and thermal conductivity. Besides, the ALD reactors and processes for TFE are also reviewed. Finally, the challenges remained and future development in the stabilization of OLEDs via ALD are also discussed.
Small intestinal epithelium homeostasis involves four principal cell types: enterocytes, goblet, enteroendocrine and Paneth cells. Epidermal growth factor (EGF) has been shown to affect enterocyte differentiation. This study determined the effect of dietary EGF on goblet, enteroendocrine and Paneth cell differentiation in piglet small intestine and potential mechanisms. Forty-two weaned piglets were used in a 2 × 3 factorial design; the major factors were time post-weaning (days 7 and 14) and dietary treatment (0, 200 or 400 µg/kg EGF supplementation). The numbers of goblet and enteroendocrine cells were generally greater with the increase in time post-weaning. Moreover, the supplementation of 200 µg/kg EGF increased (P < 0.01) the number of goblet and enteroendocrine cells in villus and crypt of the piglet small intestine as compared with the control. Dietary supplementation with 200 µg/kg EGF enhanced (P < 0.05) abundances of differentiation-related genes atonal homologue 1, mucin 2 and intestinal trefoil factor 3 messenger RNA (mRNA) as compared with the control. Piglets fed 200 or 400 µg/kg EGF diet had increased (P < 0.05) abundances of growth factor-independent 1, SAM pointed domain containing ETS transcription factor and pancreatic and duodenal homeobox 1 mRNA, but decreased the abundance (P < 0.01) of E74 like ETS transcription factor 3 mRNA as compared with the control. Animals receiving 400 µg/kg EGF diets had enhanced (P < 0.05) abundances of neurogenin3 and SRY-box containing gene 9 mRNA as compared with the control. The mRNA abundance and protein expression of lysozyme, a marker of Paneth cell, were also increased (P < 0.05) in those animals. As compared with the control, dietary supplementation with 200 µg/kg EGF increased the abundance of EGF receptor mRNA and the ratio of non-phospho(p)-β-catenin/β-catenin (P < 0.05) in villus epithelial cells at days 7 and 14. This ratio in crypt epithelial cells was higher (P < 0.05) on the both 200 and 400 µg/kg EGF groups during the same period. Our results demonstrated that dietary EGF stimulated goblet, enteroendocrine and Paneth cell differentiation in piglets during the post-weaning period, partly through EGFR and Wnt/β-catenin signalling.
Hand, foot and mouth disease (HFMD) has spread widely and leads to high disease burden in many countries. However, relative transmissibility from male to female individuals remains unclear. HFMD surveillance database was built in Shenzhen City from 2013 to 2017. An intersex transmission susceptible–infectious–recovered model was developed to calculate the transmission relative rate among male individuals, among female individuals, from male to female and from female to male. Two indicators, ratio of transmission relative rate (Rβ) and relative transmissibility index (RTI), were developed to assess the relative transmissibility of male vs. female. During the study period, 270 347 HFMD cases were reported in the city, among which 16 were death cases with a fatality of 0.0059%. Reported incidence of total cases, male cases and female cases was 0.0057 (range: 0.0036–0.0058), 0.0052 (range: 0.0032–0.0053) and 0.0044 (range: 0.0026–0.0047), respectively. The difference was statistically significant between male and female (t = 3.046, P = 0.002). Rβ of male vs. female, female vs. female, from female to male vs. female and from male to female vs. female was 7.69, 1.00, 1.74 and 7.13, respectively. RTI of male vs. female, female vs. female, from female to male vs. female and from male to female vs. female was 3.08, 1.00, 1.88 and 1.43, respectively. Transmissibility of HFMD is different between male and female individuals. Male cases seem to be more transmissible than female.
We extend the vortex-surface field (VSF), whose isosurface is a vortex surface consisting of vortex lines, to identify vortex tubes and sheets in homogeneous isotropic turbulence. The VSF at a time instant is constructed by solving a pseudo-transport equation. This equation is convected by a given instantaneous vorticity obtained from direct numerical simulation. In each pseudo-time step, we develop a novel local optimization algorithm to minimize a hybrid VSF constraint, balancing the accuracy and smoothness of VSF solutions. This key improvement makes the numerical construction of VSFs feasible for arbitrarily complex flow fields, as a general flow diagnostic tool. In the visualization of VSF isosurfaces in decaying homogeneous isotropic turbulence, the initial curved vortex sheets first evolve into vortex tubes, and then the vortex tubes are stretched and tangled, constituting a complex network. Some vortex tubes exhibit helical geometry, which suggests the important role of vortex twisting in the generation of small-scale structures in energy cascade.
This study aimed to determine whether increased carotenoids intake was associated with reduced risk of gestational diabetes mellitus (GDM). We performed a cross-sectional analysis using data from Tongji Maternal and Child Health Cohort study. The dietary carotenoids intake of 1978 pregnant women was assessed using a researcher-administered FFQ before undertaking an oral glucose tolerance test at 24–28 weeks. Multivariate logistic and linear regression analyses were used to obtain the effect estimates. Participants in the highest quartile of lycopene intake showed a lower risk of GDM (OR 0·50; 95 % CI 0·29, 0·86; Pfor trend = 0·007) compared with those in the lowest quartile; each 1 mg increase in lycopene consumption was associated with a 5 % (95 % CI 0·91, 0·99; Pfor trend = 0·020) decrease in GDM risk. No significant association was found between α-carotene, β-carotene, β-cryptoxanthin, lutein/zeaxanthin intake and GDM risk. Multiple linear regression analysis suggested an inverse association between lycopene intake and fasting blood glucose (FBG) (Pfor trend < 0·001); each 1 mg increase in lycopene intake was associated with 0·005 (95 % CI 0·002, 0·007; Pfor trend < 0·001) mmol/l decrease in FBG. Interaction analysis indicated consistent effect on each age or pre-BMI subgroup; however, a stronger protective effect of lycopene intake against GDM was observed among primigravid women (OR 0·20; 95 % CI 0·07, 0·55 in the highest v. the lowest quartile of intake; Pfor interaction = 0·036). In conclusion, dietary lycopene intake was mainly assumed via reducing FBG to decrease GDM risk, and the protection was relatively increased among primigravid women.
Image stitching is important for the perception and manipulation of undersea robots. In spite of a well-developed technique, it is still challenging for undersea images because of their inevitable appearance ambiguity caused by the limited light in the undersea environment, and local disturbance caused by moving objects, ocean current, etc. To get a clean and stable background panorama in the undersea environment, this paper proposes an undersea image-stitching method by introducing graph-based registration and blending procedures. Specifically, in the registration procedure, matching the features in each undersea image pair is formulated and solved by graph matching, to incorporate the structural information between features. In the blending procedure, an energy function on the indirect graph Markov random field is proposed, which takes both image consistency and neighboring consistency into consideration. Coincidentally, both graph matching and energy minimization can be mathematically formulated by integer quadratic programming problems with different constraints; the recently proposed graduated nonconvexity and concavity procedure is used to optimize both problems. Experiments on both synthetic images and real-world undersea images witness the effectiveness of the proposed method.
We present updated U–Pb ages and Hf isotopic compositions of detrital zircons and whole-rock geochemical data to investigate the provenance and tectonic setting of late Neoproterozoic and early Cambrian sandstones from the Cathaysia Block, in order to offer new constraints on its tectonic evolution and its palaeo-position within the supercontinent. The source rocks for the studied sandstones were dominated by felsic–intermediate materials with moderate weathering history. U–Pb dating results show major populations at c. 2500 Ma, 1000–900 Ma and 870–716 Ma with subordinate peaks at 655–532 Ma, consistent with the global Neoarchean continental crust growth, assembly and break-up of Rodinia, and Pan-African Event associated with the formation of Gondwana. Zircon U–Pb ages and Hf isotopic data suggest that most derived from exotic terranes once connected to the Cathaysia Block. Using whole-rock geochemical analysis, it was determined that the studied sedimentary rocks were deposited in a passive continental margin and the Cathaysia and Yangtze blocks were part of the same continent; no Cambrian ocean existed between them. Compiling a detrital zircon dataset from Qiangtang, northern India, the Lhasa Terrane and Western Australia, the Cathaysia Block seems to be more similar to the Qiangtang and western part of the northern India margin, instead of having a direct connection with the Lhasa Terrane and Western Australia in the Gondwana reconstruction during the late Neoproterozoic and Cambrian eons.
We demonstrate that, if a globally smooth virtual circulation-preserving velocity exists, Kelvin’s and Helmholtz’s theorems can be extended to some non-ideal flows which are viscous, baroclinic or with non-conservative body forces. Then we track vortex surfaces frozen in the virtual velocity in the non-ideal flows, based on the evolution of a vortex-surface field (VSF). For a flow with a viscous-like diffusion term normal to the vorticity, we obtain an explicit virtual velocity to accurately track vortex surfaces in time. This modified flow is dissipative but prohibits reconnection of vortex lines. If a globally smooth virtual velocity does not exist, an approximate virtual velocity can still facilitate the tracking of vortex surfaces in non-ideal flows. In a magnetohydrodynamic Taylor–Green flow, we find that the conservation of vorticity flux is significantly improved in the VSF evolution convected by the approximate virtual velocity instead of the physical velocity, and the spurious vortex deformation induced by the Lorentz force is eliminated.
Maternal dietary patterns and macronutrients intake have been shown to affect the development of gestational diabetes mellitus (GDM), but the findings are inconsistent. We aimed to identify maternal dietary patterns and examine their associations with GDM risk, and to evaluate the contributions of macronutrients intake to these associations. We included 2755 Chinese pregnant women from the Tongji Maternal and Child Health Cohort. Dietary intakes were assessed using a validated semi-quantitative FFQ 2 weeks before the diagnosis of GDM. GDM (n 248) was diagnosed based on the results of a 75-g, 2-h oral glucose tolerance test at 24–28 weeks gestation. We derived five different dietary patterns from a principal component analysis. The results showed that high fish–meat–eggs scores, which were positively related to protein intake and inversely related to carbohydrate intake, were associated with a higher risk of GDM (adjusted OR for quartile 4 v. quartile 1: 1·83; 95 % CI 1·21, 2·79; Ptrend=0·007) and higher plasma glucose levels. In contrast, high rice–wheat–fruits scores, which were positively related to carbohydrate intake and inversely related to protein intake, were associated with lower risk of GDM (adjusted OR for quartile 3 v. quartile 1: 0·54; 95 % CI 0·36, 0·83; Ptrend=0·010) and lower plasma glucose levels. In addition, dietary protein and carbohydrate intake significantly contributed to the associations between dietary patterns and GDM risk or glucose levels. These findings suggest that a dietary pattern characterised by high protein and low carbohydrate intake in pregnancy was associated with a higher risk of GDM, which may provide important clues for dietary guidance during pregnancy to prevent GDM.
Given the global water challenges, solar-driven steam generation has become a renewed topic recently as an energy-efficient way for clean water production. Here, a hybrid plasmonic structure consisting of a top layer of TiN nanoparticles (NPs) and a bottom layer of mesoporous anodized alumina membrane (AAM) was rationally designed and fabricated. The top TiN NPs with broadband light absorption acted as a plasmonic heating layer, which converted the absorbed light to heat efficiently for interfacial water heating. The AAM acted as the mechanical support layer, guaranteeing the heat isolation and continuous water replenishment. With optimized thickness of the TiN top layer, a solar steam generation efficiency of 87.7% was achieved in this study. This efficiency is comparable or even higher than prior studies. The current work proves the capability of the TiN NPs as an alternative photothermal material.
As the co-enzyme of pyruvate dehydrogenase and α-ketoglutarate dehydrogenase, thiamine plays a critical role in carbohydrate metabolism in dairy cows. Apart from feedstuff, microbial thiamine synthesis in the rumen is the main source for dairy cows. However, the amount of ruminal thiamine synthesis, which is influenced by dietary N levels and forage to concentrate ratio, varies greatly. Notably, when dairy cows are overfed high-grain diets, subacute ruminal acidosis (SARA) occurs and results in thiamine deficiency. Thiamine deficiency is characterised by decreased ruminal and blood thiamine concentrations and an increased blood thiamine pyrophosphate effect to >45 %. Thiamine deficiency caused by SARA is mainly related to the increased thiamine requirement during high grain feeding, decreased bacterial thiamine synthesis in the rumen, increased thiamine degradation by thiaminase, and decreased thiamine absorption by transporters. Interestingly, thiamine deficiency can be reversed by exogenous thiamine supplementation in the diet. Besides, thiamine supplementation has beneficial effects in dairy cows, such as increased milk and component production and attenuated SARA by improving rumen fermentation, balancing bacterial community and alleviating inflammatory response in the ruminal epithelium. However, there is no conclusive dietary thiamine recommendation for dairy cows, and the impacts of thiamine supplementation on protozoa, solid-attached bacteria, rumen wall-adherent bacteria and nutrient metabolism in dairy cows are still unclear. This knowledge is critical to understand thiamine status and function in dairy cows. Overall, the present review described the current state of knowledge on thiamine nutrition in dairy cows and the major problems that must be addressed in future research.
In this paper, a triple-wideband bandpass filter (BPF) with controllable bandwidths based on two multi-mode stub-loaded resonators (MMSLRs) and a triple-mode resonator is presented. The MMSLR is loaded with two identical folded open-ended stubs and a T-shaped stub. Each passband of the tri-band BPF is formed by four resonant modes, which provide sufficient bandwidths to meet various application requirement. By adjusting the lengths of open-ended stubs, three passband bandwidths can be controlled individually. The center frequencies of the triple-wideband BPF are allocated at 2.7, 3.67, and 5.44 GHz, with the 3 dB fractional bandwidths (FBWs) of 20.1, 14.7, and 26.3%. Among the three passbands, the highest one covers the 5 G WiFi band (5.15–5.85 GHz). The measured results of the proposed filter exhibit excellent agreement with simulated results.
Enterovirus A-71 (EV-A71) may be fatal, but the natural history, symptoms, and signs are poorly understood. This study aimed to examine the natural history of fatal EV-A71 infection and to identify the symptoms and signs of early warning of deterioration. This was a clinical observational study of fatal cases of EV-A71 infection treated at five Chinese hospitals between 1 January 2010 and 31 December 2012. We recorded and analysed 91 manifestations of EV-A71 infection in order to identify early prognosis indicators. There were 54 fatal cases. Median age was 21.5 months (Q1−Q3: 12–36). The median duration from onset to death was 78.5 h (range, 6 to 432). The multilayer perceptron analysis showed that ataxia respiratory, ultrahyperpyrexia, excessive tachycardia, refractory shock, absent pharyngeal reflex, irregular respiratory rhythm, hyperventilation, deep coma, pulmonary oedema and/or haemorrhage, excessive hypertension, tachycardia, somnolence, CRT extension, fatigue or sleepiness and age were associated with death. Autopsy findings (n = 2) showed neuronal necrosis, softening, perivascular cuffing, colloid and neuronophagia phenomenon in the brainstem. The fatal cases of enterovirus A71 had neurologic involvement, even at the early stage. Direct virus invasion through the neural pathway and subsequent brainstem damage might explain the rapid progression to death.
In this paper, a dual-wideband bandpass filter (BPF) with independently controllable center frequencies (CFs) and wide stopband suppression is presented using a new quintuple-mode resonator (QMR). By applying the classical odd-/even-mode analysis method, the resonant characteristics of the new QMR have been analyzed. It shows that five modes can be excited, and two of them can be employed to form the lower passband, while the other three modes contribute to the higher passband. For verification, a dual-wideband BPF using the new QMR is designed, fabricated, and tested. Experimental results show that the CFs of the dual-wideband BPF centered at 2.96 GHz and 5.695 GHz with 3 dB fractional bandwidths of 27.7 and 23.4%, respectively. In addition, 20-dB suppression in upper-stopband ranges from 2.23 to 4.04f0, where f0 is the center frequency of the first passband. The measurement results are in good agreement with the prediction results.
A facile synthesis procedure of nitrogen-self-doped porous carbon (NPC) derived from abundant natural biological materials has been presented. The pyrolysis temperature and the weight ratio of Co3O4 to carbon play a key role in determining microscopic structure and electrochemical performances of the final materials. The ordered mesostructures with nanopores in the channel walls provided support for immobilization of well-dispersed Co3O4 nanoparticles. They also served as a highly conductive substrate for effectively alleviating severe particle aggregation during the charge/discharge processes, which prevented capacity fading from deteriorated electric contact between the components. Taking advantage of the interconnected porous structures and high specific surface area (1799 m2/g) of carbon substrate, the Co3O4/NPC composite as anode in lithium-ion battery delivers a stable reversible capacity of 903 mA h/g after 400 cycles. It is expected that by loading other electrode active materials on such carbon material, the manufacture of the promising anode materials with excellent cycle stability is highly possible.
Perinatal exposure to nutrients and dietary components may affect the risk for coeliac disease (CD). We investigated the association between maternal use of vitamin D, n-3 fatty acids (FA) and Fe supplements during pregnancy and risk for CD autoimmunity (CDA) and CD in the offspring. Children at increased genetic risk were prospectively followed from birth in The Environmental Determinants of Diabetes in the Young (TEDDY) study. CDA was defined as having persistently positive tissue transglutaminase autoantibodies (tTGA). Diagnosis of CD was either biopsy-confirmed or considered likely if having persistently elevated levels of tTGA>100 AU. Of 6627 enrolled children, 1136 developed CDA at a median 3·1 years of age (range 0·9–10) and 409 developed CD at a median 3·9 years of age (range 1·2–11). Use of supplements containing vitamin D, n-3 FA and Fe was recalled by 66, 17 and 94 % of mothers, respectively, at 3–4 months postpartum. The mean cumulative intake over the entire pregnancy was 2014 μg vitamin D (sd 2045 μg), 111 g n-3 FA (sd 303 g) and 8806 mg Fe (sd 7017 mg). After adjusting for country, child’s human leucocyte antigen genotype, sex, family history of CD, any breast-feeding duration and household crowding, Cox’s proportional hazard ratios did not suggest a statistically significant association between the intake of vitamin D, n-3 FA or Fe, and risk for CDA or CD. Dietary supplementation during pregnancy may help boost nutrient intake, but it is not likely to modify the risk for the disease in the offspring.