Assessment of Phenolics-Related Antinutritive Levels using the In Vitro Gas Production Technique: A Comparison Between Different Types of Polyvinylpolypyrrolidone or Polyethylene Glycol

The use of different types of phenolic binding agents (PBA) in conjunction with the in vitro gas production technique for the assessment of phenolic related antinutritive factors in browse were compared. During a grazing trial by goats, three fractions, grazed leaves (GL), ungrazed leaves (UL) or stems of ungrazed leaves (US) of Robinia pseudoacacia, together with three harvests of leaves of Cistus incanus and a summer harvest of Fraxinus ornus or Carpinus duinensis were analysed for total extractable phenols (TEPH), total extractable tannins (TETa), condensed tannins (vanillin–HCl) (TECTa) and extractable and total proanthocyanidins (TEPAs and TOPAs). Gas production from the samples with or without adding insoluble polyvinylpolypyrrolidone (IPVP), soluble PVP or polyethylene glycol of different molecular weights was measured. The kinetics of gas production were determined using the equation p=a+b (1-e^−ct). The effects of addition of the PBAs were assessed as percentage changes in the rate and volume of gas production or concentration of volatile fatty acids (VFA). Levels (mg g⁻¹ DM) of TEPH varied from 4·9 to 100·4, TETa from 0·6 to 58·0, TECTa from 1·0 to 64·6, and TEPas or TOPAs from 5·7 to 283·0 and from 12·4 to 331·4. Except for PVP360 which depressed fermentation, addition of 200–500 mg of the other PBAs to rumen liquor/buffer or a tannin free hay, did not affect (P>0·05) fermentation. The highest increase in gas production was achieved with PEG4, PEG8 and PEG10 followed by PVP10, PVP40 and IPVP after 12–24 h incubation. The percentage increase in gas production as a result of adding the PEGs was best associated (r=0·83–0·96; P<0·01) with the higher concentrations of total VFAs after 96 h incubation and was also best related (r=0·89–0·91; P<0.01) to the levels of extractable condensed tannins (TECTa and TEPAs) in the browse. It was concluded that PEGs were more effective than PVPs in eliminating phenolic related antinutritive factors and would be preferred for use in conjunction with the gas technique for the assessment of phenolic related antinutritive factors in feeds.     

Poly(lactic acid) degradation in soil or under controlled conditions

The fate of a racemic lactic acid polymer (PLA50) was investigated by allowing parallelepiped plates of PLA50 to age in liquid medium containing a mixed culture of Fusarium moniliforme and Pseudomonas putida at 30°C. Microbial activity was monitored by measuring pH, lactic acid formation by high-performance liquid chromatography, and esterase activity in supernatant. Degradation of the plates was monitored by weighing, size exclusion chromatography, and visual examination. Under the selected conditions, pH increased up to 8, whereas it remained constant in the microorganism-free control. No significant lactic acid formation or esterase activity was detected in the supernatant during the experimental period (32 weeks). For the first 17 weeks, the water absorption rate of the plates was the same in both the microbial and the control media. Subsequently, plates absorbed more water in microbial than in control media. Typical surface/center differential degradation of plates was observed until 17 weeks, but it reduced progressively. At 32 weeks, specimens appeared completely disintegrated in the microbial medium. PLA50 plates were also buried in the soil for 8 weeks. After recovery, plates were allowed to degrade 8 weeks under controlled conditions. Scanning electron microscopy of these plates showed the development of some filamentous fungi at the surface and into the bulk of plates. Five fungal strains were isolated which appeared to be able to assimilate PLA50 oligomers in mixed cultures. It was assumed that PLA50 plates had been first degraded by chemical hydrolysis, followed by the bioassimilation of degradation by-products in both experiments. © 1996 John Wiley & Sons. Inc.     

Complex Event Detection in Extremely Resource-Constrained Wireless Sensor Networks

Complex Events are sequences of sensor measurements indicating interesting or unusual activity in the monitored process. Such events are ubiquitous in a wide range of Wireless Sensor Network (WSN) applications, yet there does not exist a common mechanism that addresses both the considerable constraints of WSNs and the specific properties of Complex Events. We argue that Complex Events cannot be described using standard threshold-based or composite logic approaches and attempting to represent them as such can lead to unpredictable execution cost while detection accuracy suffers from erroneous recording of observations which are common in WSNs. To address this, we develop a family of Complex Event Detection (CED) algorithms based on online symbolic conversion of sensor readings. With fixed execution cost and modest resource requirements, the CED algorithms cater for exact, approximate, non-parametric, multiple and probabilistic detection that is neither application nor data dependent. Overall, full implementation and simulations provide experimental evidence of the advantages of the proposed approach. We find that the proposed algorithms minimise configuration, promote unattended operation and complement the goal of prolonged lifetime—factors that satisfy the long-term research vision predicting Internet-scale WSNs comprising billions of devices.     

Demand for broadband access in Greece

As broadband access networks are relatively new in Greece, it is really difficult and involves great risk to determine the potential market for broadband services. The intent of this paper is to add to the discussion of delivering fixed broadband lines to customers in Greece taking into account regulation issues, the strategic movements of the market key players and the commonly admitted inequality of broadband access availability between urban and rural areas. In addition, using time-series analysis and examining the correlations between the number of fixed broadband lines and specific demographic factors for the past three years (mid 2006–mid 2009), an attempt to estimate empirically the forthcoming demand for broadband lines is conducted. Population’s income and effective competition are recognized as the strongest determinants of broadband development. In addition, it yields that demand for broadband will continue to have a positive trend for the years to come as people are becoming more and more familiar with new technologies, with youth being the pioneer to the use of innovative services that require broadband access.     

Effects of low and high temperatures on tensile behavior of adhesively-bonded GFRP joints

The tensile behavior of adhesively-bonded double-lap joints composed of pultruded glass fiber-reinforced adherends and an epoxy adhesive was investigated under temperatures ranging between −35 °C and 60 °C. The load–elongation response was influenced primarily by the thermomechanical behavior of the adhesive and much less so by that of the adherends. For temperatures above the adhesive glass transition temperature, strength and stiffness decreased with the former being less affected than the latter. The failure mechanism changed with increasing temperature from fiber-tear to adhesive failure. The crack initiation loads were unaffected as long as the temperature remained below the adhesive glass transition temperature. However, the crack propagation rate was higher at low temperatures. Critical strain energy release rates for crack initiation and propagation consistently rose as temperature increased. Modeling results obtained using existing empirical models and FEA compared well to the experimental data in the examined temperature range.     

Production scheduling with uncertain supply: a new solution to the open pit mining problem

The annual production scheduling of open pit mines determines an optimal sequence for annually extracting the mineralized material from the ground. The objective of the optimization process is usually to maximize the total Net Present Value (NPV) of the operation. Production scheduling is typically a Mixed Integer Programming (MIP) type problem containing uncertainty in the geologic input data and economic parameters involved. Major uncertainty affecting optimization is uncertainty in the mineralized materials (resource) available in the ground which constitutes an uncertain supply for mine production scheduling. A new optimization model is developed herein based on two-stage Stochastic Integer Programming (SIP) to integrate uncertain supply to optimization; past optimization methods assume certainty in the supply from the mineral resource. As input, the SIP model utilizes a set of multiple, stochastically simulated scenarios of the mineralized materials in the ground. This set of multiple, equally probable scenarios describes the uncertainty in the mineral resource available in the ground, and allows the proposed model to generate a single optimum production schedule. The method is applied for optimizing the annual production scheduling at a gold mine in Australia and benchmarked against a traditional scheduling method using the traditional single “average type” assessment of the mineral resource in the ground. In the case study presented herein, the schedule generated using the proposed SIP model resulted in approximately 10% higher NPV than the schedule derived from the traditional approach.     

Experimental investigation of R-ratio effects on fatigue crack growth of adhesively-bonded pultruded GFRP DCB joints under CA loading

A series of fatigue experiments was performed in order to investigate the effect of the R-ratio on the fatigue/fracture behavior of adhesively-bonded pultruded GFRP double cantilever beam joints. Constant amplitude fatigue experiments were carried out under displacement control with a frequency of 5 Hz in ambient laboratory conditions. Three different R-ratios were applied: R = 0.1, R = 0.5 and R = 0.8. The crack length was determined by means of crack gages and a dynamic compliance method. The dominant failure mode was a fiber-tear failure that occurred in the mat layers of the pultruded laminates. The depth of the crack location significantly affected the energy dissipated for the fracture under cyclic loading. Short-fiber and roving bridging increased the fracture resistance during crack propagation. Fatigue crack growth curves were derived for each R-ratio and each observed crack path location. The fatigue threshold and slope of the fatigue crack growth curve significantly increased with increased R-ratio.     

Microfabricated Ion-Selective Transistors with Fast and Super-Nernstian Response

Transistor-based ion sensors have evolved significantly, but the best-performing ones rely on a liquid electrolyte as an internal ion reservoir between the ion-selective membrane and the channel. This liquid reservoir makes sensor miniaturization difficult and leads to devices that are bulky and have limited mechanical flexibility, which is holding back the development of high-performance wearable/implantable ion sensors. This work demonstrates microfabricated ion-selective organic electrochemical transistors (OECTs) with a transconductance of 4 mS, in which a thin polyelectrolyte film with mobile sodium ions replaces the liquid reservoir. These devices are capable of selective detection of various ions with a fast response time (≈1 s), a super-Nernstian sensitivity (85 mV dec⁻¹), and a high current sensitivity (224 µA dec⁻¹), comparing favorably to other ion sensors based on traditional and emerging materials. Furthermore, the ion-selective OECTs are stable with highly reproducible sensitivity even after 5 months. These characteristics pave the way for new applications in implantable and wearable electronics.