Early Post Mortem pH decrease in porcine M. longissimus dorsi of PSE, Normal and DFD quality

The purpose of this investigation was to compare the muscle pH at exsanguination and the rate of pH changes in porcine M. longissimus dorsi (LD) of normal, DFD (Dark, Firm, Dry) and PSE (Pale, Soft, Exudative) quality. The pH was continuously measured in the LD in 116 carcasses during the first 50 min post mortem. Calculations were made both on measured pH-values and on pH-values transformed to hydrogen ion concentrations. A regression of pH or hydrogen ion concentration on time was made for each animal. These individual regressions were then combined, using a multivariate analysis to estimate regression curves for each meat quality class. The two methods for expressing pH gave somewhat different results. The relationship between the hydrogen ion concentration and time was found to be linear for normal and DFD muscles and quadratic for PSE muscles. As a consequence of the mathematical properties of pH, the relationship between pH and time was found to be quadratic for the normal and DFD qualities, and linear for the PSE quality. For both methods of calculations the slopes for the regression curves were significantly different between PSE and the other two quality classes with both calculating methods, while the slopes did not differ between normal and DFD muscle qualities. The intercepts of the regression curves differed significantly between PSE and the other two quality classes only when the calculations were made on measured pH-values without transformation. A temporary increase in pH was seen in some normal and PSE carcasses during the measured time period. Development of muscles with PSE characteristics thus seems to be initiated by a combination of a lower muscle-pH already at exsanguination and a faster pH decrease. It is also of importance to consider the special mathematical properties of the pH-value.     

Intestinal absorption of retinol and retinyl palmitate in the rat. Effects of tetrahydrolipstatin

The aim of the present study was to characterize the intestinal absorption of retinol and retinyl palmitate in thoracic duct and bile duct fistulated rats and to investigate the effect of a simultaneously administered lipase inhibitor, tetrahydrolipstatin (THL). Absorption was determined as lymphatic recovery over a 24-hr period, including an initial 12-hr continuous intraduodenal infusion of either [11,12-³H]retinol or [11,12-³H]retinyl palmitate given in emulsified glyceryl trioleate or in mixed micellar solution of monoolein and oleic acid. From micellar dispersion, labeled retinol and retinyl palmitate were recovered in the lymph to 50–60% and both to the same extent. Administered in emulsified form, labeled retinol from fed retinyl palmitate was recovered to 47%, but retinol from fed retinol to only 18%. THL (10⁻⁴ M) in the infusate had no significant effect on the recovery of¹⁴C-labeled oleic acid. The recovery of label from emulsified glyceryl tri[1-¹⁴C]oleate was significantly decreased at this concentration of THL (76.5% vs 19.6% recovery). When administered in emulsified form, retinol absorption was not significantly affected by THL at 10⁻⁴ M, while retinyl palmitate absorption was very significantly decreased (5.0% compared to 47.8%). In the presence of THL, retinol absorption from retinyl palmitate in micellar solution was decreased (from 58% to 17%). Most of the retinol in the lymph extracts (72.2 to 91.3) was present as retinyl ester, regardless of the chemical and physical form of administration. Furthermore, THL did not induce any change in this pattern.     

Enhanced light trapping in solar cells using snow globe coating

A novel method, snow globe coating, is found to show significant enhancement of the short circuit current J_SC (35%) when applied as a scattering back reflector for polycrystalline silicon thin‐film solar cells. The coating is formed from high refractive index titania particles without containing binder and gives close to 100% reflectance for wavelengths above 400 nm. Snow globe coating is a physicochemical coating method executable in pH neutral media. The mild conditions of this process make this method applicable to many different types of solar cells. Copyright © 2012 John Wiley & Sons, Ltd.     

Chirp Control of an Electroabsorption Modulator to be used for Regeneration and Wavelength Conversion at 40 Gbit/s in All-Optical Networking

Chirp control to produce low or negative values of chirp at the output of an electroabsorption modulator (EAM) is an important mechanism for reducing the signal degradation due to chromatic dispersion in high-speed transmission over standard single-mode fibre. An analytical model for the chirp performance of an EAM capable of optical regeneration and simultaneous wavelength conversion operating at 40 Gbit/s is derived. A chirp control approach is identified using this model by exploring the tradeoff between the α-parameter describing the chirp factor (based on the nonlinear absorption coefficients) and bias voltage requirements of an EAM. In particular, an optimum range of bias voltage is determined to ensure reduced chirp operation when a two-tone signal (i.e., comprised of bias and modulating voltages) is applied to the EAM. It is also demonstrated for large signal operation at 40 Gbit/s that the optimum range of reverse bias voltage is between 0 and 2 V to obtain low values for the chirp factor (between +1 and −2) in order to facilitate the necessary chirp control in all-optical networking. In addition, it is identified that at 40 Gbit/s higher positive values of the second- and third- order nonlinear coefficients of chirp must be avoided when operating at reverse bias voltages less than 1 V.     

Photoswitchable Superabsorbency Based on Nanocellulose Aerogels

Chemical vapor deposition of a thin titanium dioxide (TiO₂) film on lightweight native nanocellulose aerogels offers a novel type of functional material that shows photoswitching between water‐superabsorbent and water‐repellent states. Cellulose nanofibrils (diameters in the range of 5–20 nm) with native crystalline internal structures are topical due to their attractive mechanical properties, and they have become relevant for applications due to the recent progress in the methods of their preparation. Highly porous, nanocellulose aerogels are here first formed by freeze‐drying from the corresponding aqueous gels. Well‐defined, nearly conformal TiO₂ coatings with thicknesses of about 7 nm are prepared by chemical vapor deposition on the aerogel skeleton. Weighing shows that such TiO₂‐coated aerogel specimens essentially do not absorb water upon immersion, which is also evidenced by a high contact angle for water of 140° on the surface. Upon UV illumination, they absorb water 16 times their own weight and show a vanishing contact angle on the surface, allowing them to be denoted as superabsorbents. Recovery of the original absorption and wetting properties occurs upon storage in the dark. That the cellulose nanofibrils spontaneously aggregate into porous sheets of different length scales during freeze‐drying is relevant: in the water‐repellent state they may stabilize air pockets, as evidenced by a high contact angle, in the superabsorbent state they facilitate rapid water‐spreading into the aerogel cavities by capillary effects. The TiO₂‐coated nanocellulose aerogels also show photo‐oxidative decomposition, i.e., photocatalytic activity, which, in combination with the porous structure, is interesting for applications such as water purification. It is expected that the present dynamic, externally controlled, organic/inorganic aerogels will open technically relevant approaches for various applications.     

Core–Shell Nanoparticle Interface and Wetting Properties

Latex colloids are among the most promising materials for broad thin film applications due to their facile surface functionalization. Yet, the effect of these colloids on chemical film and wetting properties cannot be easily evaluated. At the nanoscale, core–shell particles can deform and coalesce during thermal annealing, yielding fine‐tuned physical properties. Two different core–shell systems (soft and rigid) with identical shells but with chemically different core polymers and core sizes are investigated. The core–shell nanoparticles (NPs) are probed during thermal annealing in order to investigate their behavior as a function of nanostructure size and rigidity. X‐ray scattering allows to follow the re‐arrangement of the NPs and the structural evolution in situ during annealing. Evaluation by real‐space imaging techniques reveals a disappearance of the structural integrity and a loss of NP boundaries. The possibility to fine‐tune the wettability by tuning the core–shell NPs morphology in thin films provides a facile template methodology for repellent surfaces.     

Off‐Stoichiometric Thiol‐Ene Chemistry to Dendritic Nanogel Therapeutics

A novel platform of dendritic nanogels is herein presented, capitalizing on the self‐assembly of allyl‐functional polyesters based on dendritic‐linear‐dendritic amphiphiles followed by simple cross‐linking with complementary monomeric thiols via UV initiated off‐stoichiometric thiol‐ene chemistry. The facile approach enabled multigram creation of allyl reactive nanogel precursors, in the size range of 190–295 nm, being readily available for further modifications to display a number of core functionalities while maintaining the size distribution and characteristics of the master batch. The nanogels are evaluated as carriers of a spread of chemotherapeutics by customizing the core to accommodate each individual cargo. The resulting nanogels are biocompatible, displaying diffusion controlled release of cargo, maintained therapeutic efficacy, and decreased cargo toxic side effects. Finally, the nanogels are found to successfully deliver pharmaceuticals into a 3D pancreatic spheroids tumor model.     

Kinematics of the heart: strain-rate imaging from time-resolved three-dimensional phase contrast MRI

A four-dimensional mapping (three spatial dimensions + time) of myocardial strain-rate would help to describe the mechanical properties of the myocardium, which affect important physiological factors such as the pumping performance of the ventricles. Strain-rate represents the local instantaneous deformation of the myocardium and can be calculated from the spatial gradients of the velocity field. Strain-rate has previously been calculated using one-dimensional (ultrasound) or two-dimensional (2-D) magnetic resonance imaging) techniques. However, this assumes that myocardial motion only occurs in one direction or in one plane, respectively. This paper presents a method for calculation of the time-resolved three-dimensional (3-D) strain-rate tensor using velocity vector information in a 3-D spatial grid during the whole cardiac cycle. The strain-rate tensor provides full information of both magnitude and direction of the instantaneous deformation of the myocardium. A method for visualization of the full 3-D tensor is also suggested. The tensors are visualized using ellipsoids, which display the principal directions of strain-rate and the ratio between strain-rate magnitude in each direction. The presented method reveals the principal strain-rate directions without a priori knowledge of myocardial motion directions.     

Optimum processing of qpsk signals for site diversity

For satellite communications systems which use frequencies above 10 GHz, rain and clouds attenuate signals severely, leading to an increase in bit error rate (BER) in digital links. This may be coped with by using two or more receivers on the ground, spaced far enough apart to avoid simultaneous rain outages. In this paper, a BER-minimizing decision processor is derived for two receivers and QPSK modulation. In particular, it is applied to a linear attenuating transmission channel adding independent white Gaussian noise. It is found that gains of nearly 3 dB compared to a switched system are possible in down-link limited cases.