Energy quantization in solution-processed layers of indium oxide and their application in resonant tunneling diodes

\u3cp\u3eThe formation of quantized energy states in ultrathin layers of indium oxide (In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e) grown via spin coating and thermally annealed at 200°C in air is studied. Optical absorption measurements reveal a characteristic widening of the optical band gap with reducing In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e layer thickness from ≈43 to ≈3 nm in agreement with theoretical predictions for an infinite quantum well. Through sequential deposition of In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e and gallium oxide (Ga\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e) layers, superlattice-like structures with controlled dimensionality and spatially varying conduction band characteristics are demonstrated. This simple method is then explored for the fabrication of functional double-barrier resonant tunneling diodes. Nanoscale current mapping analysis using conductive atomic force microscopy reveals that resonant tunneling is not uniform but localized in specific regions of the apparent device area. The latter observation is attributed to variation in the layer(s) thickness of the In\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e quantum well and/or the Ga\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e3\u3c/sub\u3e barrier layers. Despite the nonidealities, the tremendous potential of solution-processable oxide semiconductors for the development of quantum effect devices that have so far been demonstrated only via sophisticated growth techniques is demonstrated.\u3c/p\u3

Fracture mechanics testing for environmental stress cracking in thermoplastics

Under the combined influence of an aggressive environment and applied stress, engineering thermoplastics may undergo a phenomenon known as environmental stress cracking (ESC). This can result in adverse effects such as embrittlement and premature failure in service, due to the growth of environmentally-induced cracks to critical sizes, with little to no fluid absorption in the bulk material. Fracture mechanics is proposed as a suitable scheme to study and quantify ESC, with the aim being to obtain characterising data for different polymer-fluid combinations of interest, as well as to develop a reliable fracture mechanics test protocol. In the proposed method, slow crack growth is monitored to assess the effect of a range of applied crack driving forces (K, or alternatively G) on observed crack speeds, as opposed to simply measuring time-to-failure. This paper presents the results of experiments performed on the following materials: linear low density polyethylene (LLDPE) in Igepal solution and high impact polystyrene (HIPS) in sunflower oil. A discussion of the various issues surrounding the data analysis for these long-term tests is also included, as the attainment of consistent and repeatable results is critical for a method to be internationally standardised, which is a goal of the European Structural Integrity Society (ESIS) Technical Committee 4 from whose interest this work is drawn

Principles of appropriate antibiotic use for treatment of uncomplicated acute bronchitis: background.

The following principles of appropriate antibiotic use for adults with acute bronchitis apply to immunocompetent adults without complicating comorbid conditions, such as chronic lung or heart disease. The evaluation of adults with an acute cough illness or a presumptive diagnosis of uncomplicated acute bronchitis should focus on ruling out serious illness, particularly pneumonia. In healthy, nonelderly adults, pneumonia is uncommon in the absence of vital sign abnormalities or asymmetrical lung sounds, and chest radiography is usually not indicated. In patients with cough lasting 3 weeks or longer, chest radiography may be warranted in the absence of other known causes. Routine antibiotic treatment of uncomplicated acute bronchitis is not recommended, regardless of duration of cough. If pertussis infection is suspected (an unusual circumstance), a diagnostic test should be performed and antimicrobial therapy initiated. Patient satisfaction with care for acute bronchitis depends most on physician--patient communication rather than on antibiotic treatment

Thermodynamic analysis of the Quantum Critical behavior of Ce-lattice compounds

A systematic analysis of low temperature magnetic phase diagrams of Ce compounds is performed in order to recognize the thermodynamic conditions to be fulfilled by those systems to reach a quantum critical regime and, alternatively, to identify other kinds of low temperature behaviors. Based on specific heat ($C_m$) and entropy ($S_m$) results, three different types of phase diagrams are recognized: i) with the entropy involved into the ordered phase ($S_{MO}$) decreasing proportionally to the ordering temperature ($T_{MO}$), ii) those showing a transference of degrees of freedom from the ordered phase to a non-magnetic component, with their $C_m(T_{MO})$ jump ($\Delta C_m$) vanishing at finite temperature, and iii) those ending in a critical point at finite temperature because their $\Delta C_m$ do not decrease with $T_{MO}$ producing an entropy accumulation at low temperature. Only those systems belonging to the first case, i.e. with $S_{MO}\to 0$ as $T_{MO}\to 0$, can be regarded as candidates for quantum critical behavior. Their magnetic phase boundaries deviate from the classical negative curvature below $T\approx 2.5$\,K, denouncing frequent misleading extrapolations down to T=0. Different characteristic concentrations are recognized and analyzed for Ce-ligand alloyed systems. Particularly, a pre-critical region is identified, where the nature of the magnetic transition undergoes significant modifications, with its $\partial C_m/\partial T$ discontinuity strongly affected by magnetic field and showing an increasing remnant entropy at $T\to 0$. Physical constraints arising from the third law at $T\to 0$ are discussed and recognized from experimental results

Stochastic dominance to account for uncertainty and risk in conservation decisions

Practical conservation normally requires making decisions in the face of uncertainty. Our attitude toward that uncertainty, and the risks it entails, shape the way conservation decisions are made. Stochastic dominance (SD), a method more commonly used in economics, can be used to rank alternative conservation actions by comparing the probability distributions of their outcomes, making progressive simplified assumptions about the preferences of decision makers. Here, we illustrate the application of SD to conservation decisions using the recovery plan for an endangered frog species in Australia as a case study. Stochastic dominance is simple and intuitively appealing for conservation decisions; its broader application may encourage conservation decision makers to consider probabilistic uncertainty in light of their preferences, which may otherwise be difficult to recognize and assess transparently. A better treatment of attitudes towards uncertainty and risk may help ensure rational decision making in conservation and remove potential causes of stakeholder conflict

Asymptotic behaviour of estimators of the parameters of nearly unstable INAR(1) models

A sequence of first-order integer-valued autoregressive type (INAR(1)) processes is investigated, where the autoregressive type coefficients converge to 1. It is shown that the limiting distribution of the joint conditional least squares estimators for this coefficient and for the mean of the innovation is normal. Consequences for sequences of Galton{Watson branching processes with unobservable immigration, where the mean of the offspring distribution converges to 1 (which is the critical value), are discussed

Retinal thickness in eyes with mild nonproliferative retinopathy in patients with type 2 diabetes mellitus: comparison of measurements obtained by retinal thickness analysis and optical coherence tomography

OBJECTIVE: To compare measurements of retinal thickness in eyes with mild nonproliferative retinopathy in patients with type 2 diabetes mellitus using 2 different techniques: the retinal thickness analyzer (RTA) and optical coherence tomography (OCT). METHODS: Twenty-eight eyes from 28 patients with type 2 diabetes mellitus and mild nonproliferative retinopathy were classified according to the Wisconsin grading system by 7-field stereoscopic fundus photography. Ten eyes were classified as level 10 (absence of visible lesions) and 18 as level 20 or 35 (minimal retinopathy). All eyes were examined by the RTA and OCT. Healthy populations were used to establish reference maps for the RTA (n = 14; mean age, 48 years; age range, 42-55 years) and OCT (n = 10; mean age, 56 years; age range, 43-68 years). Reference maps were computed using the means + 2 SDs of the values obtained for each location. Increases in thickness were computed as a percentage of increase over these reference maps. RESULTS: The RTA detected increases in thickness in 1 or more locations in 24 of the 28 diabetic eyes examined, whereas OCT detected increases in only 3 eyes. The percentages of increase detected by the RTA ranged from 0.3% to 73.5%, whereas OCT detected percentages of increase of 0.3% to 4.8%. CONCLUSION: Optical coherence tomography is less sensitive than the RTA in detecting localized increases in retinal thickness in the initial stages of diabetic retinal disease

Dynamic analysis of sugar metabolism in different harvest seasons of pineapple (Ananas comosus L. (Merr.))

In pineapple fruits, sugar accumulation plays an important role in flavor characteristics, which varies according to the stage of fruit development. Metabolic changes in the contents of fructose, sucrose and glucose and reducing sugar related to the activities of soluble acid invertase (AI), neutral invertase (NI), sucrose synathase (SS) and sucrose-phosphate synthase (SPS) were studied in winter and summer pineapple fruits in this paper. Sucrose was significantly increased in most of the harvesting winter fruits which reached the peak of 64.87 mg·g-1 FW at 130 days after anthesis, while hexose was mainly accumulated at the 90 day of the summer fruits in July. The ratio of hexose to sucrose was 5.92:0.73 from the winter fruit in February. Interestingly, the activities of SPS and SS synthetic direction of the harvested fruits in February were significantly higher than those in July, whereas the invertase activities were exactly opposite. NI activity showed a similar trend to AI, but the amount of NI activity was higher than AI in both months. Therefore, NI appears to be one of the vital enzymes in pineapple fruit development. Conclusively, the enzyme activities related to sugar play key roles in the eating of quality pineapple, which could be improved by cultivation in different seasons. So we can arbitrate different temperature to improve the quality of pineapple fruits according to market demand.Keywords: Pineapple (Ananas comosus), different harvest seasons, sucrose, sucrose phosphate synthase, sucrose synthas