Substituent effects on thermal and photo‐alignment behavior of poly(ethylene imine)s carrying azobenzene side groups

A new class of liquid‐crystalline poly(ethylene imine)s (PEIs) having four differently substituted (? CN,? C₄H₉,? OCH₃ and? NO₂) azobenzene side‐chain groups attached through alkyl spacer groups were successfully synthesized using a solution polycondensation reaction. The synthesized polymers were characterized using differential scanning calorimetry, polarized optical microscopy and X‐ray diffraction. The photochemical, thermo‐optical and photo‐orientational behavior of the polymers were investigated in detail. Spin‐coated films of PEIs with azobenzene groups having? C₄H₉,? OCH₃ and? NO₂ substituents showed out‐of‐plane molecular orientation on annealing. Except for the PEI with an azobenzene group having ? NO₂ substituent, all polymers exhibited good photoresponsive properties upon irradiation with UV and visible light. Films of PEIs with azobenzene side groups having? CN,? C₄H₉ and? OCH₃ substituents showed reversible alignment behavior from random state to out‐of‐plane and from out‐of‐plane to random state on annealing and on irradiation with UV and non‐polarized visible light. The reversibility of the molecular orientation of PEIs from random state to out‐of‐plane and from out‐of‐plane to random state greatly depended on the substituent attached to the azobenzene side‐chain group. Copyright © 2010 Society of Chemical Industry     

Non-destructive assessment of instrumental and sensory tenderness of lamb meat using NIR hyperspectral imaging

The purpose of this study was to develop and test a hyperspectral imaging system (900–1700 nm) to predict instrumental and sensory tenderness of lamb meat. Warner–Bratzler shear force (WBSF) values and sensory scores by trained panellists were collected as the indicator of instrumental and sensory tenderness, respectively. Partial least squares regression models were developed for predicting instrumental and sensory tenderness with reasonable accuracy (R_cv = 0.84 for WBSF and 0.69 for sensory tenderness). Overall, the results confirmed that the spectral data could become an interesting screening tool to quickly categorise lamb steaks in good (i.e. tender) and bad (i.e. tough) based on WBSF values and sensory scores with overall accuracy of about 94.51% and 91%, respectively. Successive projections algorithm (SPA) was used to select the most important wavelengths for WBSF prediction. Additionally, textural features from Gray Level Co-occurrence Matrix (GLCM) were extracted to determine the correlation between textural features and WBSF values.     

Synthesis and characterization of the as-deposited Cd1 ? x Pb x S thin films prepared by spray pyrolysis technique

Cd_{1 ? x} Pb _x S thin films were prepared by spray pyrolysis technique onto glass substrate at 300°C temperatures. The prepared films were characterized elemental, structural and optical properties by energy dispersive X-ray, scanning electron microscopy, X-ray diffraction and UV-VIS spectrophotometer. Energy dispersive X-ray confirmed the presence of Cd, S and Pb in the films. SEM images show that the deposition covered the substrate well uniformly and incorporation of Pb. Crystal structure was found hexagonal and the estimated grain size was lies in between 9 to 49 nm. The optical band gap was decreased from 2.43 to 2.07 eV.     

Self and static interference mitigation scheme for coexisting wireless networks

High density of coexisting networks in the Industrial, Scientific and Medical (ISM) band leads to static and self interferences among different communication entities. The inevitability of these interferences demands for interference avoidance schemes to ensure reliability of network operations. This paper proposes a novel Diversified Adaptive Frequency Rolling (DAFR) technique for frequency hopping in Bluetooth piconets. DAFR employs intelligent hopping procedures in order to mitigate self interferences, weeds out the static interferer efficiently and ensures sufficient frequency diversity. We compare the performance of our proposed technique with the widely used existing frequency hopping techniques, namely, Adaptive Frequency Hopping (AFH) and Adaptive Frequency Rolling (AFR). Simulation studies validate the significant improvement in goodput and hopping diversity of our scheme compared to other schemes and demonstrate its potential benefit in real world deployment.     

Isolation and characterization of the Shiga toxin gene (stx)-bearing Escherichia coli O157 and non-O157 from retail meats in Shandong Province, China, and characterization of the O157-derived stx2 phages

Infection by Shiga toxin (Stx)-producing Escherichia coli of non-O157 and O157 serotypes are rare in China, but infection by O157 serotype was found in Shandong Province and three other provinces in China. To understand the reason for these rare infections and to determine the safety of retail meats in Shandong Province, we examined the distribution of Shiga toxin gene (stx)-bearing E. coli in retail meats and characterized the isolated stx-bearing strains. We used hybridization with DNA probes and isolated stx1- and/or stx2-positive E. coli from 31 (58%) of 53 retail meat samples, with beef showing the highest frequency (68%). Of 42 stx-positive isolates, none belonged to O157. Using the O157-specific immunomagnetic bead technique, we isolated E. coli O157 carrying the eae and stx2 genes from eight beef samples (26%). These strains produced little or no Stx2 and carried a unique q gene. Replication of the stx2 phages was detected in these strains, whereas stx2 phage replication was not detected in our previous study in which we examined similar stx2-bearing E. coli O157 strains from other Asian countries. Analysis of E. coli C600 lysogenized with the stx2 phages found in this study suggests that the lack of Stx2 production is due to changes in non-q gene region(s) of the phage genome or chromosomal mutation(s) in the host. Our data and reports by other workers suggest it is necessary to determine if various stx2-bearing E. coli O157 strains producing Stx2 to varying degrees are distributed in meats in various locations in China.     

A comparative study on the electronic and optical properties of Sb<Subscript>2</Subscript>Se<Subscript>3</Subscript> thin film

The thin film of Sb₂Se₃ was deposited by thermal evaporation method and the film was annealed in N₂ flow in a three zone furnace at a temperature of 290°С for 30 min. The structural properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (ТЕМ), X-ray diffraction (XRD) and Raman spectroscopy, respectively. It is seen that the as-deposited film is amorphous and the annealed film is polycrystalline in nature. The surface of Sb₂Se₃ film is oxidized with a thickness of 1.15 nm investigated by X-ray photolecetron spectroscopy (XPS) measurement. Spectroscopic ellipsometry (SE) and UV–vis spectroscopy measurements were carried out to study the optical properties of Sb₂Se₃ film. In addition, the first principles calculations were applied to study the electronic and optical properties of Sb₂Se₃. From the theoretical calculation it is seen that Sb₂Se₃ is intrinsically an indirect band gap semiconductor. Importantly, the experimental band gap is in good agreement with the theoretical band gap. Furthermore, the experimental values of n, k, ε₁, and ε₂ are much closer to the theoretical results. However, the obtained large dielectric constants and refractive index values suggest that exciton binding energy in Sb₂Se₃ should be relatively small and an antireflective coating is recommended to enhance the light absorption of Sb₂Se₃ for thin film solar cells application.     

Hierarchical Fuzzy Systems Integrated with Particle Swarm Optimization for Daily Reference Evapotranspiration Prediction: a Novel Approach

Water Resources Management - Reference evapotranspiration (ET0) is a crucial element for deriving irrigation scheduling of major crops. Thus, precise projection of ET0 is essential for better...     

Application of artificial intelligence to improve quality of service in computer networks

Resource sharing between book-ahead (BA) and instantaneous request (IR) reservation often results in high preemption rates for ongoing IR calls in computer networks. High IR call preemption rates cause interruptions to service continuity, which is considered detrimental in a QoS-enabled network. A number of call admission control models have been proposed in the literature to reduce preemption rates for ongoing IR calls. Many of these models use a tuning parameter to achieve certain level of preemption rate. This paper presents an artificial neural network (ANN) model to dynamically control the preemption rate of ongoing calls in a QoS-enabled network. The model maps network traffic parameters and desired operating preemption rate by network operator providing the best for the network under consideration into appropriate tuning parameter. Once trained, this model can be used to automatically estimate the tuning parameter value necessary to achieve the desired operating preemption rates. Simulation results show that the preemption rate attained by the model closely matches with the target rate.     

A data mining approach for machine fault diagnosis based on associated frequency patterns

Bearings play a crucial role in rotational machines and their failure is one of the foremost causes of breakdowns in rotary machinery. Their functionality is directly relevant to the operational performance, service life and efficiency of these machines. Therefore, bearing fault identification is very significant. The accuracy of fault or anomaly detection by the current techniques is not adequate. We propose a data mining-based framework for fault identification and anomaly detection from machine vibration data. In this framework, to capture the useful knowledge from the vibration data stream (VDS), we first pre-process the data using Fast Fourier Transform (FFT) to extract the frequency signature and then build a compact tree called SAFP-tree (sliding window associated frequency pattern tree), and propose a mining algorithm called SAFP. Our SAFP algorithm can mine associated frequency patterns (i.e., fault frequency signatures) in the current window of VDS and use them to identify faults in the bearing data. Finally, SAFP is further enhanced to SAFP-AD for anomaly detection by determining the normal behavior measure (NBM) from the extracted frequency patterns. The results show that our technique is very efficient in identifying faults and detecting anomalies over VDS and can be used for remote machine health diagnosis.     

GEOPHYSICAL CHARACTERIZATION OF THE SANGU GAS FIELD,OFFSHORE, BANGLADESH: CONSTRAINTS ON RESERVOIRS

The only produced offshore gas field in Bangladesh, known as the Sangu field, is located in the Hatiya Trough in the east of the Bay of Bengal, and has estimated total reserves of about 1055 BCF GIIP. The early shut-down of the field in October 2013 may have resulted in significant volumes of recoverable gas being left in the subsurface over a depth range of 1893 m to 3640 m. In this paper, seismic and well log data were analyzed and interpreted in order to investigate the structure and stratigraphy of the Sangu field, together with the lithology, extent and petrophysical properties of the reservoir. The general lithostratigraphy at Sangu has some similarity to that of the Surma Basin of the Bengal Foredeep. Reservoir rocks consist of Miocene and Pliocene deltaic sandstones and deep-water clastics. The source rock is the Miocene Bhuban Shale which is mature for gas generation in the Hatiya Trough. Three Neogene seismic stratigraphic megasequences were recognised at Sangu and are interpreted to have been deposited respectively in fluvial, delta front and shelf slope or marginal marine settings. Based on an analysis of wireline logs from wells Sangu-1 and Sangu-5 and on seismic-to-well ties, a series of reservoir units referred to (from the base up) as the T1 (E, D, C, A&B), Supra-T1, T2 and T3 have been identified. Petrophysical analyses showed that the average total porosity of these reservoir units is >13%, the permeability is in general less than10 mD, and the gas saturation ranges from 24% to 80%. Mapping of the reservoirs shows that the structure at Sangu is an asymmetric anticline with a NNW-SSE axial trend. Amplitude data have allowed the delineation of two other potential reservoir zones in the field at depths of 2900-3000 m and 3550-3750 m. The study will contribute to future offshore gas exploration and development in the Bay of Bengal region based on the geological and geophysical characteristics of the reservoirs delineated.