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Flexible and stretchable capacitive pressure sensors have been developed in recent years due to their potential applications in health monitoring, robot skins, body activity measurements and so on. In order to enhance sensor sensitivity, researchers have changed structure of the dielectric of parallel plate capacitive sensor . Here we enhance the sensor sensitivities by changing electrode composition and explore the use of a woven electrode structure sensor with silver coated nylon yarn and EcoflexTM. The woven structure enhanced sensitivity 2.3 times relative to a simple cross-grid geometry (sensitivity was 0.003 kPa-1). Furthermore, it is also observed that the sensor with the woven electrode also had better repeatability and showed less creep than a device using carbon black electrodes. The woven structure of the electrodes enabled the device to be compliant, despite the presence of the stiff nylon fibres – thereby enabling good sensitivity without the creep seen in softer electrodes.
A novel pressure sensor is proposed exhibiting generative properties from
displacement-induced ionic charge separation in gel electrolytes. A
mechano-ionic or ‘piezo-ionic’ effect, in analogy to the
well-known piezoelectric effect, is hypothesized to originate from a difference
in mobilities between cationic and anionic species causing a localized ionic
charge gradient upon application of pressure. This gradient can be detected as a
voltage or current by using copper electrodes placed at the sides or at regular
intervals along a surface of the gel. The voltage generated may be a result of
the local concentration gradient induced by the deformation of the gel or
perhaps is the result of some ions moving faster through the porous gel than
others. In this work, ionic polymer gels based on Poly(vinylidene
fluoride-hexafluoropropylene) (PVDF-HFP) co-polymer were synthesized in
situ to incorporate an organic electrolyte consisting of
bis(trifluoromethane)sulfonimide lithium salt in propylene carbonate. With two
electrodes placed under the gel, the samples were subjected to a sinusoidal
mechanical force while open circuit voltage was measured to determine the
relationship between electrical signal and mechanical input. The voltages
generated are 10’s of mV in magnitude at 1 kPa. Results suggest a
maximum sensitivity of 25 µV/Pa at 10 mHz, comparable to the voltages
expected in piezoelectric polymers such as PVDF (44 µV/Pa for similar
dimensions). The non-aqueous, solid-state ionic gels presented in this work
provide improved stability and is less prone to evaporation than its aqueous,
hydrogel based counterpart. The new mechanism of sensing provides an alternative
to the more rigid and less stretchable piezoelectric sensors.
The latest collection of the most up-to-date research on matters of medieval military history contains a remarkable geographical range, extending from Spain and Britain to the southern steppe lands, by way of Scandinavia, Byzantium, and the Crusader States. At one end of the timescale is a study of population in the later Roman Empire and at the other the Hundred Years War, touching on every century in between. Topics include the hardware of war, the social origins of soldiers, considerations of individual battles, and words for weapons in Old Norse literature. Contributors: Bernard S. Bachrach, Gary Baker, Michael Ehrlich, Nicholas A. Gribit, Nicolaos S. Kanellopoulos,Mollie M. Madden, Kenneth J. McMullen, Craig M. Nakashian, Mamuka Tsurtsumia, Andrew L.J. Villalon.
Reaction centers (RCs) from natural photosynthetic cells are photoactive proteins, which generate electron-hole pairs in presence of light. In a new approach presented in this work, a solution of suspended RCs with mediators has been applied as the electrolyte to build electrochemical based photovoltaic (PV) devices. In this approach, the mediators transfer charges from the RCs to the electrodes (indirect charge transfer). Various metallic and wide bandgap semiconducting materials, including Carbon, Au, Indium Tin Oxide (ITO), SnO2, WO3, have been tested as the electrodes. Among all WO3, which is a semiconductor, have shown the largest photocurrent density with an amount of ∼5.1 μA/cm2. The results show that the material of the electrode can affect the rates of the reactions in the cell. Choosing an appropriate material for the electrode, the charge transfer from the mediators to the electrode would be rectified to achieve a large photocurrent.
The high quantum efficiency (~100%) in the bacterial photosynthetic reaction center (RC) has inspired research on the application of RCs to build protein based solar cells. Conventionally, applying RCs as the photosensitive layer on the surface of a carbon electrode has shown poor photocurrents in the cells. The low photocurrent is partly due to the weak absorption of light in the monolayer of RCs. Also, an Atomic Force Microscopy image of the electrode shows lots of defects on the immobilized RCs at the electrode surface. In this work, we have built a bio-photoelectrochemical cell in which the RCs are floating in the electrolyte instead of being attached to the surface of an electrode. Despite the simple structure of the cell, the photocurrent is significantly higher in the new cell compared to when RCs are attached to an electrode. The amplitude of current reached to ~40 nA for free floating RCs, about five times larger than that in the cell with attached RCs. The aging effect was studied in both cells in a course of a week. The lifetime of attached RCs on electrode surface was slightly better than solubilized RCs in the electrolyte. Also, it is found that the mechanism which governs the charge transfer from RCs to the electrodes is the same in both bio-photoelectrochemical cells.
The aim of this study is to characterize the relationship between major depression and the metabolic syndrome in a large community based sample of Australian men and women aged 26–90 years. A lifetime history of major depression was assessed by telephone interview following the DSM–III-R. A current history of metabolic syndrome was assessed following the United States National Cholesterol Education Program Adult Treatment Panel III (NCEP AP-III) guidelines 1 to 3 years later. Logistic regression was used to estimate the association between depression and the metabolic syndrome, and its component criteria, controlling for age, sex and alcohol dependence. There was no association between a lifetime history of major depression and the presence of the metabolic syndrome. There was a weak association between depression and low high-density lipoprotein cholesterol but not with other component criteria of the metabolic syndrome. Despite calls for interventions directed at depression to reduce the onset of the metabolic syndrome there are important failures to replicate in large samples such as this, no consensus regarding the threshold at which depression may pose a significant risk even allowing for heterogeneity across populations, and no consensus regarding confounders that may explain inter-study differences. The absence of any dosage effect of depression on the associated risk for the metabolic syndrome in other unselected samples does not support a direct causal relationship. The call for intervention studies on the basis of the currently published evidence base is unwarranted.
Persistent tobacco use and excessive alcohol consumption are major public health concerns worldwide. Both alcohol and nicotine dependence (AD, ND) are genetically influenced complex disorders that exhibit a high degree of comorbidity. To identify gene variants contributing to one or both of these addictions, we first conducted a pooling-based genomewide association study (GWAS) in an Australian population, using Illumina Infinium 1M arrays. Allele frequency differences were compared between pooled DNA from case and control groups for: (1) AD, 1224 cases and 1162 controls; (2) ND, 1273 cases and 1113 controls; and (3) comorbid AD and ND, 599 cases and 488 controls. Secondly, we carried out a GWAS in independent samples from the Netherlands for AD and for ND. Thirdly, we performed a meta-analysis of the 10, 000 most significant AD- and ND-related SNPs from the Australian and Dutch samples. In the Australian GWAS, one SNP achieved genomewide significance (p < 5 x 10-8) for ND (rs964170 in ARHGAPlOon chromosome 4, p = 4.43 x 10”8) and three others for comorbid AD/ND (rs7530302 near MARK1 on chromosome 1 (p = 1.90 x 10-9), rs1784300 near DDX6 on chromosome 11 (p = 2.60 x 10-9) and rs12882384 in KIAA1409 on chromosome 14 (p = 4.86 x 10-8)). None of the SNPs achieved genomewide significance in the Australian/Dutch meta-analysis, but a gene network diagram based on the top-results revealed overrepre-sentation of genes coding for ion-channels and cell adhesion molecules. Further studies will be requirec before the detailed causes of comorbidity between AC and ND are understood.
Alcohol dependence symptoms and consumption measures were examined for stability and heritability. Data were collected from 12,045 individuals (5376 twin pairs, 1293 single twins) aged 19 to 90 years in telephone interviews conducted in three collection phases. Phases 1 and 2 were independent samples, but Phase 3 targeted families of smokers and drinkers from the Phase 1 and 2 samples. The stability of dependence symptoms and consumption was examined for 1158 individuals interviewed in both Phases 1 and 3 (mean interval = 11.0 years). For 1818 individuals interviewed in Phases 2 and 3 (mean interval = 5.5 years) the stability of consumption was examined. Heritability was examined for each collection phase and retest samples from the selected Phase 3 collection. The measures examined were a dependence score, based on DSM-IIIR and DSM-IV criteria for substance dependence, and a quantity × frequency measure. Measures were moderately stable, with test–retest correlations ranging from .58 to .61 for dependence and from .55 to .64 for consumption. However, the pattern of changes over time for dependence suggested that the measure may more strongly reflect recent than lifetime experience. Similar to previous findings, heritabilities ranged from .42 to .51 for dependence and from .31 to .51 for consumption. Consumption was significantly less heritable in the younger Phase 2 cohort (23–39 years) compared to the older Phase 1 cohort (28–90 years).
The Australian federation, as it has evolved over the past century, has a number of distinguishing characteristics. A high degree of separation of taxes with federal government control over major tax bases has led to a very high level of vertical fiscal imbalance. Much of the dynamics of center–state relations occurs against the backdrop of fiscal dominance by the federal government. Borrowing by all levels of government is subject to a process of Loan Council endorsement. With regard to redistribution, Australia employs the most elaborate system of horizontal fiscal equalization of any federation.
During the 1980s a worsening external debt position helped focus attention on structural weaknesses in the Australian economy. Efforts to rectify these weaknesses and increase public and private sector efficiency have led Australia to undergo a wide range of economic reforms, including some changes to federal institutions and arrangements, over the past two decades. There have been changes to the borrowing rules for national and subnational governments, a new tax-sharing arrangement, and reviews of intergovernmental administrative bodies. A significant increase in collaborative federalism over the past decade has facilitated major reforms to Australia's internal markets.
Over the past decade the Australian federal system has delivered substantial reform of the nation's internal markets, which has allowed Australia to increase its competitiveness and take advantage of greater global integration.
Alcohol abuse and dependence are among the most common psychiatric conditions identified in epidemiological surveys of the general population. The aim of this article is to examine the psychometric properties of Diagnostic and Statistical Manual of Mental Disorders, (4th ed.; DSM-IV; American Psychiatric Association, 1994) criteria for alcohol abuse and dependence using latent class analysis (LCA). Six thousand two hundred and sixty-five young Australian twins (median age 30 years) were interviewed by telephone between 1996 and 2000 using a modified version of the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA). DSM-IV symptoms of alcohol abuse and dependence were collected by structured diagnostic interview and analyzed using methods of LCA. LCA revealed a 4-class solution for women that classified individuals according to the severity of their alcohol- related problems: no/few problems (66.5%), heavy drinking (23.9%), moderate dependence (7.6%) and severe dependence (2.0%). Among men the preferred solution included 5 classes corresponding to no/few problems (46.4%), heavy drinking (34.3%), moderate dependence (12.2%), severe dependence (3.0%) and abuse (4.0%). Evidence of a male-specific class of alcohol-related problems corresponding to abuse partially supports the DSM conceptualization of alcohol use disorders but suggests that this conceptualization — and measurement — may need to be refined for women. Identification of a male- specific abuse class also has important implications for interventions and treatment as these individuals experienced significant alcohol-related problems and comprised approximately 21% of all men classified with an alcohol use disorder.
The DC characteristics of a Schottky contact between regioregular poly (3-hexylthiophene) and aluminum are studied in forward and reverse bias regimes. Current-voltage curves of the junction in reverse bias show a resistive path in parallel with the expected Schottky contact. This is the sign of a nonuniform junction between the metal and semiconductor that exhibits ohmic behavior in some regions. Reduction of this parallel resistance and degradation of the Schottky junction are observed over a period of two weeks. Accumulation of undesired ions in the polymer or diffusion of aluminum atoms into the semiconductor are two possible mechanisms which may explain the time dependent behavior of these Schottky junctions.
Polypyrrole exhibits actuation under electrochemical doping and undoping of the polymer matrix. Active strain and x-ray diffraction measurements are performed in order to correlate the microscopic and macroscopic structural changes occurring during actuation. Under galvanostatic reduction, the film shows first a linear contraction with oxidation state due to expulsion of small anions. At 50% of the as-grown doping level, the film reverses direction and begins to expand, possibly due to incorporation of the larger cations. X-ray diffraction, however, does not show a linear contraction or expansion in the crystalline portions of the polymer. The polymer crystallites go through a sudden contraction in one dimension of approximately 14%, and otherwise remain constant. The contraction in the polypyrrole crystals occurs at the 50% doping level, and may be correlated with the reversal of macroscopic actuation.
Polypyrrole actuators offer attractive possibilities due to their large electrochemical stress (>5MPa), moderate to large strain (>2 %) and low voltage operation (<2 V). However, little is known about their temperature dependence response, with nearly all previous tests performed at room temperature. To test the effects of increasing temperature, polypyrrole films in water and propylene carbonate were thermally cycled twice from 22°C to 80°C. Length and actuation were measured before, after and between cycling. Results show that polypyrrole in TBAPF6(propylene carbonate) underwent a 4.8% irrecoverable contraction during the first cycle and lost half it’s actuation each cycle. Polypyrrole in NaPF6(aq) showed a 2.1% initial expansion in length on the first cycle followed by a 2.1% contraction on the next cycle, while active strain amplitude dropped from 7.7% to 5.9% to 4.9%. Polypyrrole in NaCl(aq) has a net contraction of 6% over two cycles with no significant change in it’s original 3.5% actuation amplitude. This suggests that although films in NaPF6(aq) have the best initial strain, films in NaCl(aq) maintain the most consistent strain amplitude in response to temperature on the timescales observed. Strain to charge ratio was found to decrease slightly, but the majority of the loss in actuation for films is correlated with a reduction in charge transfer each cycle. This reduction may result from a reduction in the active volume of film.