Organosilica Monoliths with Multiscale Porosity: Detailed Investigation of the Influence of the Surfactant on Structure Formation

Monolithic inorganic-organic hybrid materials have been synthesized via sol-gel processing of an ethylene glycol-modified ethane-bridged silane precursor in aqueous solution of the non-ionic block copolymer Pluronic™ P123. The influence of different sol compositions on the final gel structure was investigated in detail. The resulting materials consist of macroporous networks comprising periodically arranged mesopores, where the macropore size as well as the morphology of the material can be deliberately tailored by reducing the amount of the block copolymer template. The structure was investigated by small-angle X-ray scattering as well as scanning and transmission electron microscopy. Information on the porosity, surface area and pore size distribution were obtained from BET/BJH analysis and mercury intrusion measurements. For a more detailed insight into mechanism and kinetics of the mesostructure formation, in-situ SAXS experiments were carried out.     

Hydrodistillation and in situ microwave‐generated hydrodistillation of fresh and dried mint leaves: a comparison study

BACKGROUND: Hydrodistillation (HD) has been used since ancient times for the extraction of essential oils (EO). Despite the intrinsic limitations of this technique, it remains the most common method both in the laboratory and on an industrial scale. The main drawbacks are the long extraction time involved and the risk of thermal degradation. Over the last decade, microwave‐assisted extraction (MAE) and in situ microwave‐generated hydrodistillation (MGH) have been shown to be the most promising techniques in improving plant extraction and hydrodistillation. RESULTS: In this study we compare HD with MGH in the extraction of several mint species cultivated in Piedmont: Mentha spicata L. var. rubra, Mentha spicata L. var. viridis and Mentha piperita L. MGH requires either fresh plant or rehydrated material, it is extremely fast and allows a reduction in energy consumption and overall cost. All the EO have been analyzed by gas chromatography‐mass spectrometry. A mechanism of microwave‐generated essential oil extraction has been proposed to explain the differences in the composition of the oil obtained from this environmentally friendly technique. CONCLUSIONS: The yields and composition percentages of the EO obtained by HD and in situ MGH of fresh and dried mint leaves lie in a relatively narrow range, although MGH is faster. MW polarization effects and the water solubility of the components influence extract composition Copyright © 2012 Society of Chemical Industry     

The Application of NIR FT-Raman Spectroscopy to Monitor Starch Retrogradation and Crumb Firmness in Semolina Bread

In this study, the potential application of near-infrared (NIR) Fourier-transform (FT)-Raman spectroscopy to monitor starch retrogradation in stored bread crumb was investigated. Semolina-based bread was made and cut into slices, which were stored under controlled conditions in sealed plastic bags. The aging of the bread crumb was monitored by both NIR FT-Raman spectroscopy and a texture analysis over a period of 20 days. Two-dimensional correlation analysis in the spectral range of 390–975 cm⁻¹ revealed characteristic differences among the spectra collected over time for bands that peaked at 480, 765, and 850 cm⁻¹. The band at 480 cm⁻¹ is studied here in detail. During the storage, the peak frequency of this band shifted towards lower wavenumbers, and its full width at half height decreased. Both of these parameters are highly correlated (R ² = 0.921 and R ² = 0.949, respectively) to crumb hardness measured by the texture analyzer.     

DC magnetron sputtered polyaniline-HCl thin films for chemical sensing applications

Thin films of conducting polymers exhibit unique chemical and physical properties that render them integral parts in microelectronics, energy storage devices, and chemical sensors. Overall, polyaniline (PAni) doped in acidic media has shown metal-like electronic conductivity, though exact physical and chemical properties are dependent on the polymer structure and dopant type. Difficulties arising from poor processability render production of doped PAni thin films particularly challenging. In this contribution, DC magnetron sputtering, a physical vapor deposition technique, is applied to the preparation of conductive thin films of PAni doped with hydrochloric acid (PAni-HCl) in an effort to circumvent issues associated with conventional thin film preparation methods. Samples manufactured by the sputtering method are analyzed along with samples prepared by conventional drop-casting. Physical characterization (atomic force microscopy, AFM) confirm the presence of PAni-HCl and show that films exhibit a reduced roughness and potentially pinhole-free coverage of the substrate. Spectroscopic evidence (UV-vis, FT-IR, and X-ray photoelectron spectroscopy (XPS)) suggests that structural changes and loss of conductivity, not uncommon during PAni processing, does occur during the preparation process. Finally, the applicability of sputtered films to gas-phase sensing of NH(3) was investigated with surface plasmon resonance (SPR) spectroscopy and compared to previous contributions. In summary, sputtered PAni-HCl films exhibit quantifiable, reversible behavior upon exposure to NH(3) with a calculated LOD (by method) approaching 0.4 ppm NH(3) in dry air.     

New accelerometric method to discriminate between asymptomatic subjects and patients with medial knee osteoarthritis during 3-d gait

This study presents a new method to estimate 3-D linear accelerations at tibial and femoral functional coordinate systems. The method combines the use of 3-D accelerometers, 3-D gyroscopes and reflective markers rigidly fixed on an exoskeleton and, a functional postural calibration method. Marker positions were tracked by a six-camera optoelectronic system (VICON 460, Oxford Metrics). The purpose of this study was to determine if this method could discriminate between medial osteoarthritic and asymptomatic knees during gait. Nine patients with osteoarthritic knees and nine asymptomatic control subjects were included in this study. Eighteen parameters representing maximal, minimal, and range of acceleration values were extracted during the loading and preswing to mid-swing phase periods, and were compared in both groups. Results show good discriminative capacity of the new method. Eight parameters were significantly different between both groups. The proposed method has the potential to be used in comprehending and monitoring gait strategy in patients with osteoarthritic knee.     

A Flexible UMTS-WiMax Turbo Decoder Architecture

This work proposes a VLSI decoding architecture for concatenated convolutional codes. The novelty of this architecture is twofold: 1) the possibility to switch on-the-fly from the universal mobile telecommunication system turbo decoder to the WiMax duo-binary turbo decoder with a limited resources overhead compared to a single-mode WiMax architecture; and 2) the design of a parallel, collision free WiMax decoder architecture. Compared to two single-mode solutions, the proposed architecture achieves a complexity reduction of 17.1% and 27.3% in terms of logic and memory, respectively. The proposed, flexible architecture has been characterized in terms of performance and complexity on a 0.13-mum standard cell technology, and sustains a maximum throughput of more than 70 Mb/s.     

Full Color 3-D Imaging by Digital Holography and Removal of Chromatic Aberrations

In color digital holography the recording and reconstruction of three holograms, by an optical setup operating in multi-wavelength mode, is necessary. Incorrect superposition of different images at various wavelengths may occur due to the presence of chromatic aberrations. We demonstrate that the compensation of the chromatic aberrations can be achieved by using all of the information contained in the multi-wavelength digital holograms. Chromatic aberration is extracted from phase maps reconstructed at different wavelengths, resulting in perfect full color amplitude reconstructions. The method has important applications in color 3-D holographic imaging and display.     

Soft-Magnetic Behavior of Fe-Based Nanocrystalline Alloys Produced Using Laser Powder Bed Fusion

Herein, an extensive experimental study is presented on the influence of the major process parameters of the laser powder bed fusion (LPBF) technique on the bulk density and soft-magnetic properties of Fe-based bulk metallic glasses (BMGs). For this purpose, 81 samples are manufactured using the combinations of different process parameters, that is, layer thickness (t: 50–70 μm), laser power (P: 70–130 W), laser scan speed (v: 900–1100 mm s⁻¹), and hatch spacing (h: 20–40 μm). High bulk density (≥99%) is achieved utilizing low P and v combined with low h and t in order to decrease energy input to the powder, preventing cracks associated with the brittle nature of BMGs. Furthermore, it is indicated that h = 30 μm and v = 1000 mm s⁻¹ play a determining role in acquiring high saturation magnetization (≥200 Am² kg⁻¹). Due to the laser scanning nature of the process, two distinct microstructures evolve, melt-pool (MP) and heat-affected zone (HAZ). According to thermal modeling performed in this study, laser power has the major effect on the thermal development in the microstructure (thermal gradient evolved between the two hatches and the cooling rate from MP through HAZ).     

Adsorption and Release of Sulfamethizole from Mesoporous Silica Nanoparticles Functionalised with Triethylenetetramine

Mesoporous silica nanoparticles (MSN) were synthesised and functionalised with triethylenetetramine (MSN-TETA). The samples were fully characterised (transmission electron microscopy, small angle X-ray scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential and nitrogen adsorption/desorption isotherms) and used as carriers for the adsorption of the antimicrobial drug sulphamethizole (SMZ). SMZ loading, quantified by UV–Vis spectroscopy, was higher on MSN-TETA (345.8 mg g⁻¹) compared with bare MSN (215.4 mg g⁻¹) even in the presence of a lower surface area (671 vs. 942 m² g⁻¹). The kinetics of SMZ adsorption on MSN and MSN-TETA followed a pseudo-second-order model. The adsorption isotherm is described better by a Langmuir model rather than a Temkin or Freundlich model. Release kinetics showed a burst release of SMZ from bare MSN samples (k₁ = 136 h⁻¹) in contrast to a slower release found with MSN-TETA (k₁ = 3.04 h⁻¹), suggesting attractive intermolecular interactions slow down SMZ release from MSN-TETA. In summary, the MSN surface area did not influence SMZ adsorption and release. On the contrary, the design of an effective drug delivery system must consider the intermolecular interactions between the adsorbent and the adsorbate.