We report an experimental study of the formation and evolution of laminar thermal structures generated by a small heat source, with a focus on their correlation to the thermal boundary layer and effects of heating time $t_{heat}$. The experiments are performed over the flux Rayleigh number ($Ra_f$) range $2.1\times 10^6 \leq Ra_f \leq 3.6\times 10^{7}$ and the Prandtl number ($Pr$) range $28.6 \leq Pr \leq 904.7$. The corresponding Rayleigh number ($Ra= t_{heat}\,Ra_{f}/\tau _0\,Pr$) range is $900 \leq Ra \leq 4\times 10^{4}$, where $\tau _0$ is a diffusion time scale. For thermal structures generated by continuous heating (i.e. starting plumes), their formation process exists three characteristic times that are well reflected by changes in the thermal boundary layer thickness. These characteristic times, denoted as $t_{emit}$, $t_{recover}$ and $t_{static}$, correspond to the moments when the plume emission begins and completes, and when the thermal boundary layer becomes quasi-static, respectively. Their $Ra_f$–$Pr$ dependencies are found to be $t_{emit}/\tau _0\sim Ra_f^{-0.41}\,Pr^{0.41}$, $t_{recover}/\tau _0\sim Ra_f^{-0.48}\,Pr^{0.48}$ and $t_{static}/\tau _0\sim Ra_f^{-0.49}\,Pr^{0.33}$, respectively. Thermal structures generated by finite $t_{heat}$ exhibit similar evolution dynamics once $t_{heat} \ge t_{emit}$, with the accelerating stage behaving like starting plumes and the decay stage like thermals (i.e. a finite amount of buoyant fluids). It is further found that their maximum rising velocity experiences a transition in the $Ra$-dependence from $Ra$ to $(Ra\ln Ra)^{0.5}$ at $Ra \simeq 6000$; and their maximum acceleration reaches the value of starting plumes at $t_{heat}\simeq t_{recover}$, and remains unchanged for larger $t_{heat}$. In particular, the maximum rising velocity for the cases with $t_{heat} = t_{recover}$ follows a scaling relation $Ra_f^{0.37}\,Pr^{-0.37}$, in contrast to the relation $Ra_f^{0.48}\,Pr^{-0.48}$ for starting plumes. This study provides a more comprehensive understanding of laminar thermal structures, which are relevant to a range of processes in nature and laboratory systems such as Rayleigh–Bénard convection.

Cystic echinococcosis (CE) occurs in the intermediate host's liver, assuming a bladder-like structure surrounded by the host-derived collagen capsule mainly derived from activated hepatic stellate cells (HSCs). However, the effect of CE on liver natural killer (NK) cells and the potential of transforming growth factor-β (TGF-β) signalling inhibition on alleviating CE-related liver damage remain to be explored. Here, by using the CE-mouse model, we revealed that the inhibitory receptors on the surface of liver NK cells were up-regulated, whereas the activating receptors were down-regulated over time. TGF-β1 secretion was elevated in liver tissues and mainly derived from macrophages. A combination of TGF-β signalling inhibitors SB525334 and pirfenidone could reduce the expression of TGF-β1 signalling pathway-related proteins and collagen production. Based on the secretion of TGF-β1, only the pirfenidone group showed a depressing effect. Also, the combination of SB525334 and pirfenidone exhibited a higher potential in effectively alleviating the senescence of the hepatocytes and restoring liver function. Together, TGF-β1 may be a potential target for the treatment of CE-associated liver fibrosis.

The present study was conducted to test the hypothesis that dietary supplementation with a nano chitosan–zinc complex (CP–Zn, 100 mg/kg Zn) could alleviate weaning stress in piglets challenged with enterotoxigenic Escherichia coli K88 by improving growth performance and intestinal antioxidant capacity. The in vivo effects of CP–Zn on growth performance variables (including gastrointestinal digestion and absorption functions and the levels of key proteins related to muscle growth) and the antioxidant capacity of the small intestine (SI) were evaluated in seventy-two weaned piglets. The porcine jejunal epithelial cell line IPEC-J2 was used to further investigate the antioxidant mechanism of CP–Zn in vitro. The results showed that CP–Zn supplementation increased the jejunal villus height and decreased the diarrhoea rate in weaned piglets. CP–Zn supplementation also improved growth performance (average daily gain and average daily feed intake), increased the activity of carbohydrate digestion-related enzymes (amylase, maltase, sucrase and lactase) and the mRNA expression levels of nutrient transporters (Na+-dependent glucose transporter 1, glucose transporter type 2, peptide transporter 1 and excitatory amino acid carrier 1) in the jejunum and up-regulated the expression levels of mammalian target of rapamycin (mTOR) pathway-related proteins (insulin receptor substrate 1, phospho-mTOR and phospho-p70S6K) in muscle. In addition, CP–Zn supplementation increased glutathione content, enhanced total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-px) activity, and reduced malondialdehyde (MDA) content in the jejunum. Furthermore, CP–Zn decreased the content of MDA and reactive oxygen species, enhanced the activity of T-SOD and GSH-px and up-regulated the expression levels of nuclear factor erythroid 2-related factor 2 (Nrf2) pathway-related proteins (Nrf2, NAD(P)H:quinone oxidoreductase 1 and haeme oxygenase 1) in lipopolysaccharide-stimulated IPEC-J2 cells. Collectively, these findings indicate that CP–Zn supplementation can improve growth performance and the antioxidant capacity of the SI in piglets, thus alleviating weaning stress.

Chlamydia spp. are a group of obligate intracellular pathogens causing a number of diseases in animals and humans. Avian chlamydiosis (AC), caused by Chlamydia psittaci (C. psittaci) as well as new emerging C. avium, C. gallinacea and C. ibidis, have been described in nearly 500 avian species worldwidely. The Crested Ibis (Nipponia nippon) is a world endangered avian species with limited population and vulnerable for various infections. To get a better understanding of the prevalence of Chlamydia spp. in the endangered Crested Ibis, faecal samples were collected and analysed. The results confirmed that 20.20% (20/99) of the faecal samples were positive for Chlamydiaceae and were identified as C. ibidis with co-existence of C. psittaci in one of the 20 positive samples. In addition, ompA sequence of C. psittaci obtained in this study was classified into the provisional genotype Matt116, while that of C. ibidis showed high genetic diversity, sharing only 77% identity with C. ibidis reference strain 10-1398/6. We report for the first time the presence of C. ibidis and C. psittaci in the Crested Ibis, which may indicate a potential threat to the endangered birds and should be aware of the future protection practice.

M3:2 high-speed steel (HSS) billets with or without Nb addition were prepared by spray deposition. The effects of Nb and post-thermal-mechanical processing (decomposition treatment and hot forging), as well as heat treatment, on the microstructure and properties of M3:2 HSS were investigated. The microstructure of the as-deposited M3:2 HSS consisted of equiaxed grains with a mean size of approximately 25 μm and discontinuous plate-like M2C and irregular MC carbides distributed along grain boundaries. 0.5% Nb addition can refine the M2C plates and spheroidize MC carbides. With 2% Nb addition, the refined grains with a mean size of approximately 12 μm and continuous net of M6C and a uniform distribution of NbC carbides were obtained. The decomposition of metastable M2C carbides can be accelerated with 0.5% Nb addition due to the refined size and lower thermodynamic stability of M2C plates. With the increased degree of decomposition of M2C carbide, the M6C and MC carbides became refined and more uniformly distributed after optimal thermal-mechanical processing and heat treatment, which leads to a significant increase in bend strength and toughness.

The present study determined whether α-ketoglutarate (AKG) might affect the expression of AMP-activated protein kinase (AMPK) and energy status in the intestinal mucosa of piglets challenged with Escherichia coli lipopolysaccharide (LPS). A total of eighteen piglets (weaned at 21 d of age) were allocated to one of three treatments: (1) non-challenged (control); (2) LPS-challenged (LPS); (3) LPS+1 % AKG (LPS+AKG). Piglets in the control and LPS groups were fed a maize- and soyabean meal-based diet, and the LPS+AKG group was fed the basal diet supplemented with 1 % AKG. On days 10, 12, 14 and 16 of the trial, piglets in the LPS and LPS+AKG groups were challenged with LPS (80 μg/kg body weight), whereas piglets in the control group received the same volume of sterile saline. Pigs were euthanised 24 h after the last administration of LPS or saline to obtain intestinal mucosae for biochemical analysis. Compared with the control group, LPS administration decreased (P < 0·05) the oxidation of AKG, oleic acid, glutamine and glucose in enterocytes, decreased concentrations of ATP in the duodenal and jejunal mucosae and decreased adenylate energy charge (AMP:ATP ratio) in the jejunal and ileal mucosae. Additionally, LPS treatment reduced (P < 0·05) mucosal concentrations of phosphorylated AMPK in the jejunum and ileum as well as acetyl-CoA carboxylase in all segments of the small intestine. The adverse effects of LPS were reversed by AKG. Collectively, these results indicate that dietary supplementation with 1 % AKG beneficially modulates the AMPK signalling pathway to improve energy status in the small intestine of LPS-challenged piglets.

We introduce fixpoint definitions, a rule-based reformulation of fixpoint constructs. The logic FO(FD), an extension of classical logic with fixpoint definitions, is defined. We illustrate the relation between FO(FD) and FO(ID), which is developed as an integration of two knowledge representation paradigms. The satisfiability problem for FO(FD) is investigated by first reducing FO(FD) to difference logic and then using solvers for difference logic. These reductions are evaluated in the computation of models for FO(FD) theories representing fairness conditions and we provide potential applications of FO(FD).

We present a systematic method for proving non-terminating basic hypergeometric identities. Assume that k is the summation index. By setting a parameter x to xqn, we may find a recurrence relation of the summation by using the q-Zeilberger algorithm. This method applies to almost all non-terminating basic hypergeometric summation formulae in the work of Gasper and Rahman. Furthermore, by comparing the recursions and the limit values, we may verify many classical transformation formulae, including the Sears–Carlitz transformation, transformations of the very well-poised 8φ7 series, the Rogers–Fine identity and the limiting case of Watson's formula that implies the Rogers–Ramanujan identities.

Few studies have been conducted to investigate ecological roles of litter amphibians in forest ecosystems. In this study, ten field enclosures (3 m × 2 m × 0.4 m) were used to evaluate effects of the toad Bufo bankorensis on the abundance of litter invertebrates (microbivores, fragmenters and predatory arthropods) and litter decomposition rates in a subtropical forest of southern Taiwan. Litterbags collected from toad and control (toad-excluded) enclosures were analysed for the communities and abundances of litter invertebrates and decay loss during this decomposition study from September to December 2001. The presence of B. bankorensis significantly changed phosphorus concentrations in the litter, but not the densities of litter invertebrates (microbivores, fragmenters and predatory arthropods) or rates of litter decomposition. These results were not consistent with previous studies, which have shown that Plethodon cenereus in a temperate forest of north-east USA and Eleutherodactylus coqui in a tropical rain forest of Puerto Rico significantly changed decomposition rates. We suggest that ecological roles of ground-dwelling amphibians may be species-specific and vary with different terrestrial ecosystems.

Optical thin films with SiO2-TiO2 stack were prepared by the technology of electron beam (e-beam) evaporation with ion beam assistant deposition (IBAD). The mechanical (stress) and optical properties of as-deposited thin films were studied as a function of exposure time in the atmospheric environment. Exposing to the air at the ambient temperature causes incremental compressive stress and spectrum profile changes, which is related to the absorption of water moisture into the films. Making a dense film is, therefore, a practical approach to improve structural stability of thin films and then the performance of optical devices.

Control of the film stress and optical property has long been considered as an issue in the tunable optical MEMS (Micro-Electro-Mechanical Systems) devices. In this paper, the atmospheric evolution of Titanium Dioxide (TiO2) and Silicon Dioxide (SiO2) thin films for the optical MEMS devices were studied. These films were prepared by ion-assisted e-beam evaporation. It is found that as-deposited SiO2 films exhibit compressive stress; whereas, it is tensile in the TiO2 films under present processing conditions. When annealed at 150 °C, both SiO2 and TiO2 films show slight changes in stress with annealing time. However, increasing the anneal temperature to 250°C caused an apparent change of film stresses with time, in which SiO2 film turns into less compressive and TiO2 film appears to be more tensile. The optical properties after annealing were also investigated by measuring the thickness and the refractive index changes using the spectroscopic ellipsometry technique. At both experimental temperatures, the film thickness increases slightly and the refractive index at 1550 nm decreases a little at the initial annealing stage for SiO2 films. For TiO2 films, it is found that the refractive index increases after annealing at 250°C. This might be caused by the TiO2 film densification process during amorphous-to-crystalline phase transformation. Because most of the significant film evolutions occur during the initial 12 hours of annealing, a practical way of stabilizing the film properties in a MEMS device is to pre-anneal the as-deposited thin films.

The optical and mechanical properties of TiO2 film prepared by ion-assisted e-beam evaporation have been examined in this research. Spectroscopic ellipsometry analysis revealed an inhomogeneous behavior in both optical property and growth structure, vertically from substrate to the top surface of the film. This phenomenon was further confirmed with the electron microscopic analyses. The effects of deposition rate, chamber pressure, anode voltage and current on the stress of TiO2 films were also investigated and reported. Further study showed that a structural homogeneous film could be obtained through TiO2-SiO2 co-evaporation.

Dense, uniform, and adherent chemically vapor-deposited mullite coatings were deposited on SiC substrates using the AlCl3–SiCl4–H2–CO2 system. Typical coating morphology consisted of a thin interfacial layer of γ–Al2O3 nanocrystallites embedded within a vitreous SiO2-based matrix. When a critical Al/Si ratio of 3.2 ± 0.29 was reached within this nanocrystalline layer, mullite crystals nucleated and grew as columnar grains. The thickness of the nanocrystalline layer decreased as the input AlCl3/SiCl4 ratio was increased. In all cases, the Al/Si composition in the coating increased from the coating/substrate interface to the coating surface. Critical factors leading to the nucleation and growth of mullite crystals are discussed in this article.