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The coexistence of multiple stable states is indicative of self-organising processes occurring in the course of the combustor-inlet interactions in a ramjet engine and give rise to the appearance of various nonlinear phenomena. This paper provides a dynamic model that can describe the multiple stable states and the corresponding nonlinear effects to further investigate the dynamic interactions between combustor and inlet in a ramjet engine. Our study shows the whole engine can display distinct dynamic behaviours ranging from irreversibility to hysteresis and to various mode transitions, depending on different physical parameters. With the model, we also illustrate the role of the instability of the normal shock wave in impacting the whole engine’s nonlinear dynamics. Additionally, we extend the previous studies of the classification of combustor-inlet interactions from a static framework to a dynamic framework, which helps to clarify the transient processes of the nonlinear interactions. This work offers a quantitative illustration of the combustor-inlet interactions in a ramjet engine by revealing its nonlinear dynamics and associated characteristics, therefore advancing our understanding of the nonlinear phenomena that exhibit in ramjet engines.
The fatty acid composition of chicken’s meat is largely influenced by dietary lipids, which are often used as supplements to increase dietary caloric density. The underlying key metabolites and pathways influenced by dietary oils remain poorly known in chickens. The objective of this study was to explore the underlying metabolic mechanisms of how diets supplemented with mixed or a single oil with distinct fatty acid composition influence the fatty acid profile in breast muscle of Qingyuan chickens. Birds were fed a corn-soybean meal diet supplemented with either soybean oil (control, CON) or equal amounts of mixed edible oils (MEO; soybean oil : lard : fish oil : coconut oil = 1 : 1 : 0.5 : 0.5) from 1 to 120 days of age. Growth performance and fatty acid composition of muscle lipids were analysed. LC-MS was applied to investigate the effects of CON v. MEO diets on lipid-related metabolites in the muscle of chickens at day 120. Compared with the CON diet, chickens fed the MEO diet had a lower feed conversion ratio (P < 0.05), higher proportions of lauric acid (C12:0), myristic acid (C14:0), palmitoleic acid (C16:1n-7), oleic acid (C18:1n-9), EPA (C20:5n-3) and DHA (C22:6n-3), and a lower linoleic acid (C18:2n-6) content in breast muscle (P < 0.05). Muscle metabolome profiling showed that the most differentially abundant metabolites are phospholipids, including phosphatidylcholines (PC) and phosphatidylethanolamines (PE), which enriched the glycerophospholipid metabolism (P < 0.05). These key differentially abundant metabolites – PC (14:0/20:4), PC (18:1/14:1), PC (18:0/14:1), PC (18:0/18:4), PC (20:0/18:4), PE (22:0/P-16:0), PE (24:0/20:5), PE (22:2/P-18:1), PE (24:0/18:4) – were closely associated with the contents of C12:0, C14:0, DHA and C18:2n-6 in muscle lipids (P < 0.05). The content of glutathione metabolite was higher with MEO than CON diet (P < 0.05). Based on these results, it can be concluded that the diet supplemented with MEO reduced the feed conversion ratio, enriched the content of n-3 fatty acids and modified the related metabolites (including PC, PE and glutathione) in breast muscle of chickens.
Section 1 of the FM14 focus on bridging the astronomy research and outreach communities - recent highlights, emerging collaborations, best practices and support structures. This paper also contains supplementary materials that point to contributed talks and poster presentations that can be found online.
Elastocaloric materials exhibit extraordinary cooling potential, but the repetition of cyclic mechanical loadings during long-term operation of cooling systems requires the refrigerant material to have long fatigue life. This article reviews the fundamental cause of fatigue from aspects of initiation and propagation of fatigue cracks in shape-memory alloys (SMAs) that are used as elastocaloric materials, and highlights recent advances in using compression to overcome fatigue by curtailing the generation of surfaces associated with crack propagation. Compression is identified as a key means to extend fatigue lifetime in engineering design of elastocaloric cooling drive mechanisms. We summarize the state-of-the-art performance of different SMAs as elastocaloric materials and discuss the influence of low cyclic strains and high resistance to transformation. We present integration of compression-based material assemblies into a cooling system prototype and optimization of the system efficiency using work recovery and related measures.
A total of 1145 samples were collected from chicken breeder farms, hatcheries, broiler farms, a slaughterhouse and retail refrigerated chicken stores in an integrated broiler supply chain in Guangdong Province, China, in 2013. One-hundred and two Salmonella enterica strains were isolated and subjected to serotyping, antimicrobial susceptibility testing, virulence profile determination and molecular subtyping by pulsed field gel electrophoresis (PFGE). The contamination rates in samples from breeder farms, hatcheries, broiler farms, the slaughterhouse and retail stores were 1·46%, 4·31%, 7·00%, 62·86% and 54·67%, respectively. The isolated strains of S. enterica belonged to 10 serotypes; most of them were S. Weltevreden (46·08%, 47/102) and S. Agona (18·63%, 19/102). Isolates were frequently resistant to streptomycin (38·2%), tetracycline (36·3%), sulfisoxazole (35·3%) and gentamicin (34·3%); 31·4% of isolates were multidrug resistant. The isolates were screened for 10 virulence factors. The Salmonella pathogenicity island genes avrA, ssaQ, mgtC, siiD, and sopB and the fimbrial gene bcfC were present in 100% of the strains. PFGE genotyping of the 102 S. enterica isolates yielded 24 PFGE types at an 85% similarity threshold. The PFGE patterns show that the genotypes of S. enterica in the production chain are very diverse, but some strains have 100% similarity in different parts of the production chain, which indicates that some S. enterica persist throughout the broiler supply chain.
Chinese psychiatrists have gradually started to focus on those who are deemed to be at ‘clinical high-risk (CHR)’ for psychosis; however, it is still unknown how often those individuals identified as CHR from a different country background than previously studied would transition to psychosis. The objectives of this study are to examine baseline characteristics and the timing of symptom onset, help-seeking, or transition to psychosis over a 2-year period in China.
The presence of CHR was determined with the Structured Interview for Prodromal Syndromes (SIPS) at the participants' first visit to the mental health services. A total of 86 (of 117) CHR participants completed the clinical follow-up of at least 2 years (73.5%). Conversion was determined using the criteria of presence of psychotic symptoms (in SIPS). Analyses examined baseline demographic and clinical predictors of psychosis and trajectory of symptoms over time. Survival analysis (Kaplan–Meier) methods along with Log-rank tests were performed to illustrate the relationship of baseline data to either conversion or non-conversion over time. Cox regression was performed to identify baseline predictors of conversion by the 2-year follow-up.
In total 25 (29.1%) of 86 completers transitioned to a psychotic disorder over the course of follow-up. Among the CHR sample, the mean time between attenuated symptom onset and professional help-seeking was about 4 months on average, and converters developed fully psychotic symptoms about 12 months after symptom onset. Compared with those CHR participants whose risk syndromes remitted over the course of the study, converters had significantly longer delays (p = 0.029) for their first visit to a professional in search of help. At baseline assessment, the conversion subgroup was younger, had poorer functioning, higher total SIPS positive symptom scores, longer duration of untreated prodromal symptoms, and were more often given psychosis-related diagnoses and subsequently prescribed antipsychotics in the clinic.
Chinese CHR identified primarily by a novel clinical screening approach had a 2-year transition rate comparable with those of specialised help-seeking samples world-wide. Early clinical intervention with this functionally deteriorating clinical population who are suffering from attenuated psychotic symptoms, is a next step in applying the CHR construct in China.
Although infection by the pathogenic bacterium Listeria monocytogenes is relatively rare, consequences can be severe, with a high case-fatality rate in vulnerable populations. A quantitative, probabilistic risk assessment tool was developed to compare estimates of the number of invasive listeriosis cases in vulnerable Canadian subpopulations given consumption of contaminated ready-to-eat delicatessen meats and hot dogs, under various user-defined scenarios. The model incorporates variability and uncertainty through Monte Carlo simulation. Processes considered within the model include cross-contamination, growth, risk factor prevalence, subpopulation susceptibilities, and thermal inactivation. Hypothetical contamination events were simulated. Results demonstrated varying risk depending on the consumer risk factors and implicated product (turkey delicatessen meat without growth inhibitors ranked highest for this scenario). The majority (80%) of listeriosis cases were predicted in at-risk subpopulations comprising only 20% of the total Canadian population, with the greatest number of predicted cases in the subpopulation with dialysis and/or liver disease. This tool can be used to simulate conditions and outcomes under different scenarios, such as a contamination event and/or outbreak, to inform public health interventions.
The B-biotype of Bemisia tabaci (Homoptera: Aleyrodidae) has become extremely resistant to commonly used insecticides in China. To further explore the mechanisms of resistance to diafenthiuron, the diafenthiuron induction profiles of carboxylesterase (COE1), glutathione S-transferase (GST) and seven cytochrome P450 genes in both resistant (R-DfWf) and susceptible (S-Lab) strains were characterized. The detoxification genes GST, CYP6CX4, CYP6DW3, CYP6DZ6 and CYP9F, which are known to be constitutively over-expressed in the R-DfWf strain, were significantly upregulated in R-DfWf and S-Lab strains exposed to diafenthiuron at LC50 compared with their levels in strains treated with distilled water (controls); however, CYP6CX1, another detoxification gene, was not upregulated. The upregulation was more pronounced in the R-DfWf strain than in the S-Lab strain exposed to different concentrations of diafenthiuron (LC10 or LC50). Interestingly, COE1, CYP6CM1 and CYP6A, which are not constitutively over-expressed in the R-DfWf strain, were all significantly upregulated after exposure to diafenthiuron. Similarly, significant differences in the expression of these detoxification genes, with the exception of CYP6CM1 in the S-Lab strain, were also observed after exposure to diafenthiuron. However, the induction of CYP6A and COE1 was more pronounced in the S-Lab strain than in the R-DfWf strain after treatment with diafenthiuron at both concentrations, indicating that diafenthiuron induction of CYP6CM1 is specific to the R-DfWf strain, while diafenthiuron induction of the other genes is common to both the R-DfWf and S-Lab strains. These results demonstrate that multiple detoxification genes are co-upregulated in the R-DfWf strain through both constitutive over-expression and induction mechanisms. This knowledge will be useful for rational selection of insecticides for use in resistance management and control of this species.
Emerging evidence suggests that fish consumption may have beneficial effects on mood disorders. However, no study has been reported on this issue in young adults to date. The aim of this study was to investigate the relationship between fish consumption and depressive symptoms in Japanese undergraduate students.
The 20-item Center for Epidemiologic Studies Depression Scale was used to measure depressive symptoms with a cut-off score of 16. A total of 4190 completed questionnaires (from 2124 men and 2066 women) were received for analysis.
Multivariate logistic analysis showed that fish intake was inversely associated with risk of depressive symptoms in undergraduate students. After adjustment for possible confounders, the odds-ratios (95% confidence intervals) for fish intake 1–2 times/month, 1–2 times/week, 3–4 times/week, and almost every day (compared with “almost never”) were 0.78 (0.62–0.99), 0.70 (0.56–0.87), 0.67 (0.53–0.85) and 0.65 (0.46–0.92), respectively. This association tended to be stronger in women than in men.
Frequent fish consumption in undergraduate students seems to moderate depressive symptoms. Further research is warranted to clarify the causality.
There are only a small number of prospective studies that have systematically evaluated standardised diagnostic criteria for mental disorder for more than a decade. The aim of this study is to present the approximated overall and sex-specific cumulative incidence of mental disorder in the Zurich cohort study, a prospective cohort study of 18–19 years olds from the canton of Zurich, Switzerland, who were followed through age 50.
A stratified sample of 591 participants were interviewed with the Structured Psychopathological Interview and Rating of the Social Consequences of Psychological Disturbances for Epidemiology, a semi-structured interview that uses a bottom-up approach to assess the past-year presence of 15 psychiatric syndromes. Seven interview waves took place between 1979 and 2008. Approximated cumulative incidence was estimated using Kaplan–Meier methods.
Rates of mental disorder were considerably higher than those generally reported in cross-sectional surveys. We found rates ranging from 32.5% for major depressive disorder to 1.2% for Bipolar I disorder. The cumulative probability of experiencing any of the mental disorders assessed by age 50 was 73.9%, the highest reported to date. We also found that rates differed by sex for most disorders, with females generally reporting higher rates of mood, anxiety and phobic disorder, and males reporting higher rates of substance- and alcohol-related disorders.
These findings confirm those of other long-term prospective studies that indicate the nearly universal nature of disturbances of emotion and behaviour across the life span. Greater community awareness of the normative nature of these experiences is warranted. An important area of future research is study long-term course and stability to determine who among those with such disturbances suffer from chronic disabling mental disorders. Such longitudinal studies may aid in directing services and intervention efforts where they are most needed.
Performance of a perovskite based solar cell is highly determined by the crystalline qualities of the perovskite thin film sandwiched between an electron and a hole transport layer, such as grain size and uniformity of the film. Here, we demonstrated a new hybrid physical-chemical vapor deposition (HPCVD) technique to synthesis high quality perovskite films. First, a PbI2 precursor film was spin-coated on a mesoporous TiO2 (m-TiO2)/compact TiO2 (c-TiO2)/FTO substrate in ambient environment. Then, purified CH3NH3I crystal material was evaporated and the vapor reacted with the PbI2 precursor film in a vacuum pressure/temperature accurately controlled quartz tube furnace. In this technique, high vacuum (2mTorr) and low temperature (100°C) were applied to decrease perovskite film growth rate and reduce perovskite film defects. After vapor reaction, the perovskite film was annealed at 100°C for 10min in 20mTorr vacuum to recrystallize and remove CH3NH3I residue in order to further improve crystal quality of the thin film. Crystal quality of this perovskite thin film was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). SEM and AFM results illustrate perovskite thin films synthesized by this technique have larger grain sizes and more uniformity (RMS 11.6nm/Ra 9.3nm) superior to most existing methods. Strong peaks shown in the XRD chart at 14.18°, 28.52°, 31.96°, which were assigned to (110), (220), (330) miller indices of CH3NH3PbI3 perovskite crystal, indicate the complete reaction between CH3NH3I vapor and PbI2 precursor layer. High power conversion efficiency (PCE) up to 12.3% and stable efficiencies under four hours illumination of AM1.5 standard were achieved by these solar cells. This vacuum/vapor based technique is compatible with conventional semiconductor fabrication techniques and high quality perovskite film could be achieved through delicate process control. Eventually, perovskite based solar cells could be mass produced in low cost for large scale applications by this novel technique.
In this study, we have investigated various approaches to improve CIGS solar cells after thin film deposition. CIGS devices have been fabricated by a hydrazine solution based process. Post-deposition treatments by sulfurization were studied with focuses on the change of material structures and physical properties. Sulfurization has shown to increase grain size and band gap of the absorber layers at higher temperatures. This property change has shown a direct impact on open circuit voltage of the solar cell devices. Through these post-deposition processes, improved quality of CIGS materials can be obtained and the associated solar cell devices show better performance.
Gattini and CSTAR have been installed at Dome A, Antarctica, which provide time-series photometric data for a large number of pulsating variable stars. We present the study for several variable stars with the data collected with the two facilities in 2009 to demonstrate the scientific potential of observations from Dome A for asteroseismology.
In 2008 January the 24th Chinese expedition team successfully deployed the Chinese Small Telescope ARray (CSTAR) to Dome A, the highest point on the Antarctic plateau. CSTAR consists of four 14.5cm optical telescopes, each with a different filter (g, r, i and open) and has a 4.5°×4.5° field of view (FOV). Based on the CSTAR data, initial statistics of astronomical observational site quality and light curves of variable objects were obtained. To reach higher photometric quality, we are continuing to work to overcome the effects of uneven cirrus cloud cirrus, optical “ghosts” and intra-pixel sensitivity. The snow surface stability is also tested for further astronomical observational instrument and for glaciology studies.
Using an ab initio density functional theory (DFT), we study thin film electronic properties of topological insulators (TIs) based on ternary compounds of Tl (thallium) and Bi (bismuth). We consider TlBiX2 (X=Se, Te) and Bi2X2Y (X, Y=Se, Te) compounds. Here we discuss the nature of surface states, their locations in the Brillouin Zone (BZ) and their interactions within the bulk region. Our calculations suggest a critical film thickness to maintain the Dirac cone which is smaller than that in binary Bi-based compounds. Atomic relaxations are found to affect the Dirac cone in some of these compounds. We discuss the penetration depth of surface states into the bulk region.
Carbon-coated lithium iron phosphate (C-LiFePO4) particles have been synthesized by a solid-state reaction process. Particles surface morphology, olivine-type phase structures and the carbon shell-core structures are investigated in details by transmission electron microscopy (TEM, HRTEM) imaging and electron diffraction (SAED) patterns. Homogenous features of carbon coating of the LiFePO4 particles surface are obviously revealed. HR-TEM imaging and X-ray photoelectron spectroscopy (XPS) confirmed an amorphous sp2 type conducting coating layer on the surface of LiFePO4 particles. Particles shape and size showed the clear single-crystal nature of the phospho-olivine type structures with the rough spherical features of 50-250 nm size range. The characteristics of sp2 type carbon-coating on the LiFePO4 particles surfaces allows improving the electrical conductivity and reducing the diffusion path of the lithium ions, as directly evidenced from electrochemical tests of charge-discharge cycling.