Macromolecular anchoring layers for polymer grafting: comparative study

Comparative study of efficiency of macromolecular anchoring layers in the grafting of end-functionalized polymers to a surface was conducted. Poly(glycidyl methacrylate) (PGMA) and epoxydized polybutadienes (EPB) were utilized as the primary anchoring films. Amount of the epoxy moieties introduced to the surface was varied via thickness of the modifying polymer layer or amount of epoxy groups in the polymer backbone. Comparison between the grafting of polystyrene and poly(ethylene glycol) to the various macromolecular anchoring layers indicated that grafting ability of a layer was mostly governed by thickness of the interpenetration zone between the two polymers (anchoring and being grafted). In case of low level of the interpenetration, only functional groups at the periphery of the primary polymer layer were available for the grafting. Then, amount of grafted polymer did not increase with total number of epoxy groups in the anchoring film. However, as the thickness of the interpenetration zone increased, higher amount of the functional groups become available for the grafting.     

In situ trace analysis of oil in water with mid-infrared fiberoptic chemical sensors

The determination of trace amounts of oil in water facilitates the forensic analysis on the presence and origin of oil in the aqueous environment. To this end, the present study focuses on direct sensing schemes for quantifying trace amounts of oil in water using mid-infrared (MIR) evanescent field absorption spectroscopy via fiberoptic chemical sensors. MIR transparent silver halide fibers were utilized as optical transducer for interrogating oil-in-water emulsions via the evanescent field emanating from the waveguide surface, and penetrating the surrounding aqueous environment by a couple of micrometers. Unmodified fibers and fibers surface-modified with grafted epoxidized polybutadiene layers enabled the direct detection of crude oil in a deionized water matrix at the ppm level to ppb concentration level, respectively. Thus, direct chemical sensing of crude oil IR signatures without any sample preparation as low as 46 ppb was achieved with a response time of a few seconds.     

Drug absorption and release properties of crosslinked hydrogels based on diepoxy-terminated poly(ethylene glycol)s and aliphatic polyamines — a study on the effect of the gel molecular structure

Crosslinked hydrogels with well-defined chemical structures and characteristics were prepared through the reaction between diepoxy-terminated poly(ethylene glycol)s of various molecular weights and aliphatic polyamines of different hydrocarbon chain length and functionalities, and the influence of some network parameters (molecular weight between crosslinking points, crosslinking degree, hydrophobic character) upon the absorption and release of drugs of different capacity to interact with the polymer chains was comparatively investigated. Diclofenac sodium (DCFNa) and 5-fluorouracil (5FU) were used as model drugs, based on their dissimilar hydrophobic character and ability of DCFNa to form crown ether-like complexes with PEG chains through the sodium cation. The experiments showed that the most important interactions occurring in these systems were mainly the hydrophobic ones and to a lesser extent the complexation of the Na⁺ ion by the PEG chains. Both of them were in favor of DCFNa, resulting in a larger incorporation and a slower release of this one in comparison with 5FU. For both drugs, loading was larger for hydrogels with shorter PEG chains and/or crosslinked with amines with longer hydrocarbon chain or higher functionality. Drug release tests showed a lower rate for stronger drug–network interactions in agreement with the absorption experiments.     

Evaluation of AlGaN/GaN heterostructures properties by QMSA and AFM techniques

Atomic force microscopy and Quantitative Mobility Spectrum Analysis (QMSA) were applied for characterization and evaluation of the quality of AlGaN/GaN heterostructures. The structural uniformity, growth mode and electrical properties of the heterostructures were determined. The obtained results indicated that the time of growth of the low temperature GaN nucleation layer influenced the morphology and electrical properties of the AlGaN/GaN heterostructure.     

Adjustment of Ink and Water Supply in Offset Printing

The stochasticity of the ink-water balance in the offset printing process is actually a fact. We have only the rotating speed of the duct dampening roller adjustment to apply the water to the printing plate, and against we have the ink zones which can be opened differently depending on the printing elements quantity. This means that in any way of settings we will definitely have a certain constant amount of water emulsified in a different quantity of ink. This should be so far acceptable as long as we have the wide-latitude inks in terms of tackiness, water acceptance and other rheological properties. As nowadays air modem inks are a little changed in terms of ISO 12647-2 dot gain requirements and they are now more sensitive to the very exact ink/water regulations, if looking in the very idle printing element we can consider it as a figure filled with ink-water emulsion. The water-ink flow can be described with the Ostrogradsky-Gauss formulae： ∫∫∫（V）divadxdydz = ∫∫（Ω）（a d Ω）. A divergence parameter shows the flow density in the field v which is limited by Ω1 and Ω2 surfaces on the continuously-differentiated vector-function a which should be determinative in this very point of the field. In terms of vector field flow we can explain the ink/water emulsion transfer from the printing plate to the blanket and afterwards to the imprint using also the theory of mathematical delays concerning the instability of regulations feedback. Therefore we can predict the outcome for ink emulsification in the very exact point in the printing plate and in general also.     

Influence of Different Lasers Wavelengths on Nanoparticles Components of Human Fibroblasts

Although experimental studies in vitro and vivo have been numerous, the effects of laser irradiation on human fibroblast cells are poorly understood. The aim of this study was to assess the influence on three different laser wavelengths on nanoparticles components of the human fibroblast cells from oral tumor. The cells were irradiated by 830, 920, and 2940 nm laser wavelength. The irradiated cells were incubated and their mitochondrial activity was assessed by the MTT assay at 24, 48, and 72 h. It can be concluded that the laser light with 830 nm wavelength stimulates mitochondrial activity compared to the other two wavelengths, which produce inhibition.     

An accurate MOSFET aging model for 28 nm integrated circuit simulation

MOSFET device aging represents a significant challenge for the IC industry, being increasingly more responsible for reliability failure in advanced process technology nodes. As the device electrical characteristics, such as threshold voltage and drain current, degrade with time, circuit performance also deteriorates, resulting in shorter lifetime and narrower safety margins between requirements and actual product reliability.Major device aging mechanisms include the hot-carrier injection (HCI), the negative bias-temperature instability (NBTI) for p-channel MOSFETs, and the positive bias-temperature instability (PBTI) for n-channel devices.HCI in NMOS and PMOS has been known for many years. In the presence of high electric fields, carriers are injected from the drain end of the channel into the gate dielectric, changing its electrical properties over time.PMOS NBTI has been studied in the past, and it continues to present a challenge for today’s technologies. NMOS PBTI is a phenomenon notably present in high-k metal-gate stacks. The partial recovery of degradation, an effect important for both phenomena, has been particularly challenging to model for circuit simulation, and not addressing it may result in overly pessimistic circuit lifetime predictions.In this paper we present an accurate, physics-based MOSFET aging model that encompasses degradation due to HCI, NBTI and PBTI. The model formulation on bias, geometry and temperature, and a unique methodology for modeling the AC partial-recovery effect of BTI are detailed and analyzed. The extraction methodology of the aging model parameters is further described. The model is implemented in an efficient MOSRA flow for SPICE and Fast SPICE circuit simulation, which has been successfully used to improve IC reliability-related yield in numerous 28 nm tapeouts.     

Comparative Analysis of Tunable Q-Enhancement Filter Cell Topologies in a 2.4 GHz LNA

The special LNA topologies resulting from loading a simple LNA with a set of Q-enhanced inductors are analyzed and compared. The Q of the on-chip spiral inductors that form the LNA load is enhanced by using a negative resistance realized with a cross-coupled differential pair degenerated and biased in various ways. The performance of the LNA is presented for the following types of Q-enhancement circuit: ideal negative resistor (ideal cell), tail-biased non-degenerated cross-coupled differential pair (classic cell), tail-biased resistively degenerated cross-coupled differential pair (resistive cell), tail-biased LC degenerated cross-coupled differential pair (B-cell), self-biased LC degenerated cross-coupled differential pair (BB-cell). The analysis focuses on the benefits of each cell related to s-parameter response, noise and linearity and the interdependency of Q vs. center frequency during tuning. Low voltage design challenges are addressed by presenting the advantages of the novel self-biased LC degenerated cross-coupled differential pair (BB-cell).     

Slow hot-carrier relaxation in colloidal graphene quantum dots

Reducing hot-carrier relaxation rates is of great significance in overcoming energy loss that fundamentally limits the efficiency of solar energy utilization. Semiconductor quantum dots are expected to have much slower carrier cooling because the spacing between their discrete electronic levels is much larger than phonon energy. However, the slower carrier cooling is difficult to observe due to the existence of many competing relaxation pathways. Here we show that carrier cooling in colloidal graphene quantum dots can be 2 orders of magnitude slower than in bulk materials, which could enable harvesting of hot charge carriers to improve the efficiency of solar energy conversion.     

Non-starch polysaccharides of canola meal: Quantification,digestibility in poultry and potential benefit of dietary enzyme supplementation

The non-starch polysaccharide (NSP) content as determined by gas chromatography (component neutral sugars) and colorimetry (uronic acids) was shown to be 16–22% in ten different samples of defatted canola (low glucosinolate rapeseed) seed. The non-cellulosic components of NSP accounted for 13–16% of the meal and on average consisted of arabinose (33%), xylose (13%), galactose (13%), glucose (5%), mannose (3%), rhamnose (2%), fucose (2%) and uronic acids (30%). Yellow-seeded and brown-seeded samples of canola contained similar contents of total dietary fibre although the composition of the fibre components tended to differ with the former showing a low content of lignin and associated polyphenols and a high content of NSP as compared with the latter type. NDF values tended to be lower for yellow-seeded than for brown-seeded canola due to the relatively high content of NSP in neutral detergent solubles of yellow-seeded canola. An initial balance study with laying hens showed low (<3%) digestibility of the polysaccharide components, and further studies were conducted with a commercial enzyme preparation (SP249, Novo Laboratories Ltd, Lachine, Quebec) to enhance the in-vivo hydrolysis of the NSP fraction of the meal. Laying hens were fed a semipurified diet containing 40% commercial canola meal with and without enzyme (1%). NSP digestibility was increased to 37% by the enzyme supplementation.