Nucleation behavior of blended high‐melting fractions of milk fat as affected by emulsifiers

The effect of highly hydrophobic emulsifiers, the palmitic sucrose ester P‐170 (hydrophilic/lipophilic balance (HLB) = 1.0), the stearic sucrose ester S‐170 (HLB = 1.0), the polyglycerol ester decaglycerol decastearate DAS 7S (HLB = 3.7) and the polyglycerol ester decaglycerol dodecabehenate DDB 750 (HLB = 2.6), on the nucleation of a high melting point milk fat fraction (HMF) and its blends with sunflower oil (SFO) was investigated by polarized laser light turbidimetry, X‐ray diffractometry and polarized light microscopy (PLM). Addition of polyglycerol esters accelerated nucleation, giving shorter induction times for the same supercooling. On the contrary, sucrose esters inhibited nucleation since induction times were elongated in all conditions selected. Addition of emulsifiers modified the polymorphic behavior in the blends with SFO. The β' form was promoted especially with the addition of S‐170. DAS 7S and DDB 750 promoted crystallization. PLM images showed many small crystals that did not appear in HMF images. Addition of P‐170 and S‐170 delayed nucleation and inhibited crystal growth. Crystals were notoriously smaller than the ones that appeared in HMF images. The Fisher–Turnbull model was used to calculate activation free energies of nucleation. In all cases, sucrose esters elevated the energy barrier for nucleation. Polyglycerol esters, however, if they had an effect on the energy barrier, lowered the values.     

Validation of bulk-charge effect parameter extraction in MOSFETs

Our recently proposed method to extract the bulk-charge effect parameter in MOSFETs is scrutinized by studying SOI devices, a-Si:H TFTs and short- as well as long-channel bulk MOSFETs. The method requires measuring the drain current as a function of gate voltage at two small values of drain voltage chosen in the linear region of operation.     

Analytical Techniques for Nucleation Studies in Lipids: Advantages and Disadvantages

ABSTRACT: Crystallization is generally considered a 2-step process. The 1st step, nucleation, involves the formation of molecular aggregates with a critical size great enough to become stable. During the 2nd step, nuclei grow and develop into crystals. Distinguishing between nucleation and growth constitutes a major challenge in lipid crystallization studies. Thus, it is of great importance to discuss the information obtained from the different techniques that are usually used to study nucleation behavior such as nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), rheological techniques, light-scattering techniques such as turbidimetry and scanning diffusive light scattering (SDLS), polarized light microscopy (PLM), and laser polarized optical sets such as laser polarizedlight turbidimetry (LPLT). Techniques to describe the nucleation process must be very sensitive to disregard growth. When crystallization is followed by methods such as DSC, NMR, and rheological measurements, at times, small amounts of crystals are present in the melt before any solids are detected. Clearly, at this stage, well beyond the induction time for nucleation (τ), these methods are measuring crystal growth. Techniques of low sensitivity for solid fat contents lower than 0.1% must not be used to evaluate nucleation effects. Sensitive turbidimeters with detectors that saturate below 0.3% solid fat content give good results as do scanning diffusive light-scattering equipment. Although the PLM technique is sensitive enough for these kinds of studies, an understanding of important basic concepts is essential. Laser optical sets are the most appropriated methods to study nucleation in fats systems.     

A method to extract mobility degradation and total seriesresistance of fully-depleted SOI MOSFETs

Free-carrier mobility degradation in the channel and drain/source series resistance are two important parameters limiting the performance of MOS devices. In this paper, we present a method to extract these parameters from the drain current versus gate voltage characteristics of fully-depleted (FD) SOI MOSFETs operating in the saturation region. This method is developed based on an integration function which reduces errors associated with the extraction procedure and on the DC characteristics of MOS devices having several different channel lengths. Simulation results and measured data of FD SOI MOSFETs are used to test and verify the method developed     

Characterization of MIS structures and PTFTs using TiOx deposited by spin-coating

This paper presents a method to deposit titanium oxide (TiOx) films from a sol containing IV titanium isopropoxide Ti[OCH(CH₃)₂]₄, 2-methoxyethanol, CH₃OCH₂CH₂OH and ethanolamine H₂NCH₂CH₂OH, in order to obtain layers with thickness above 220 nm with the required characteristics to be used in Metal–Insulator–Semiconductor, MIS, structures and polymeric thin film transistors, PTFTs. The effect of using different component ratios is described. The dielectric constant was in the order of 12, the critical electric field was 5 × 10⁵ V/cm and the density of states at the interface was less than 1 × 10¹¹ cm⁻². The analysis of MIS structures prepared with these TiOx layers shows that they are suitable for using in PTFTs. The fabrication of independent bottom gate PTFTs with poly(3-hexylthiophene), P3HT, on top of the TiOx layer is described, obtaining a major reduction in the operation voltage range from −30 V to −4 V, while maintaining the typical mobility for P3HT PTFTs.     

Harmonic distortion analysis using an improved charge sheet model for PD SOI MOSFETs

This work presents an Improved Charge Sheet compact Model (ICSM) especially valuable for distortion analysis, where precise calculation of derivatives of at least third order is required. A new expression for the charge is used in the calculation of the current. Vertical electric field, mobility and DIBL are represented using previously reported for other purposes more precise expressions. The very good agreement obtained between experimental PD SOI MOSFETs with channel lengths from 0.32 to 10 μm and modeled currents, derivatives and distortion figures is shown.     

FD MOS SOI circuit to enhance the ratio of illuminated to dark current of a co-integrated a-Si:H photodiode

In this paper we first present the integration of amorphous silicon photodiodes with a fully depleted silicon on isolator (FD SOI) MOSFET circuit. Taking the advantage of the better subthreshold characteristic of FD SOI MOSFETs with respect to bulk devices, a very simple SOI circuit integrated with the amorphous silicon photodiode is presented to significantly improve the ratio of the circuit output current when the diode is illuminated to when it is not. The use of one additional reference source voltage to adjust the operating point of the photodiode, allows to obtain a very significant increase in this current ratio, much higher than what can be obtained using a simple diode. Circuit solutions used to amplify the diode current under illumination are usually more complicated and involve a capacitor or more transistors than the circuit we present. All the other properties of the photodetector, as its spectral characteristic and linear dependence of detection with light intensity are maintained. The circuit can also be used in conjunction with other circuits for further amplification and/or processing.