60 research outputs found
Hot-Carrier Cooling in High-Quality Graphene is Intrinsically Limited by Optical Phonons
Many promising optoelectronic devices, such as broadband photodetectors,
nonlinear frequency converters, and building blocks for data communication
systems, exploit photoexcited charge carriers in graphene. For these systems,
it is essential to understand, and eventually control, the cooling dynamics of
the photoinduced hot-carrier distribution. There is, however, still an active
debate on the different mechanisms that contribute to hot-carrier cooling. In
particular, the intrinsic cooling mechanism that ultimately limits the cooling
dynamics remains an open question. Here, we address this question by studying
two technologically relevant systems, consisting of high-quality graphene with
a mobility >10,000 cmVs and environments that do not
efficiently take up electronic heat from graphene: WSe-encapsulated
graphene and suspended graphene. We study the cooling dynamics of these two
high-quality graphene systems using ultrafast pump-probe spectroscopy at room
temperature. Cooling via disorder-assisted acoustic phonon scattering and
out-of-plane heat transfer to the environment is relatively inefficient in
these systems, predicting a cooling time of tens of picoseconds. However, we
observe much faster cooling, on a timescale of a few picoseconds. We attribute
this to an intrinsic cooling mechanism, where carriers in the hot-carrier
distribution with enough kinetic energy emit optical phonons. During phonon
emission, the electronic system continuously re-thermalizes, re-creating
carriers with enough energy to emit optical phonons. We develop an analytical
model that explains the observed dynamics, where cooling is eventually limited
by optical-to-acoustic phonon coupling. These fundamental insights into the
intrinsic cooling mechanism of hot carriers in graphene will play a key role in
guiding the development of graphene-based optoelectronic devices
Wheat Seed Proteins: Factors Influencing Their Content, Composition, and Technological Properties, and Strategies to Reduce Adverse Reactions
Wheat is the primary source of nutrition for many, especially those living in developing countries, and wheat proteins are among the most widely consumed dietary proteins in the world. However, concerns about disorders related to the consumption of wheat and/or wheat gluten proteins have increased sharply in the last 20 years. This review focuses on wheat gluten proteins and amylase trypsin inhibitors, which are considered to be responsible for eliciting most of the intestinal and extraintestinal symptoms experienced by susceptible individuals. Although several approaches have been proposed to reduce the exposure to gluten or immunogenic peptides resulting from its digestion, none have proven sufficiently effective for general use in coeliac-safe diets. Potential approaches to manipulate the content, composition, and technological properties of wheat proteins are therefore discussed, as well as the effects of using gluten isolates in various food systems. Finally, some aspects of the use of gluten-free commodities are discussed
Electroendosmotic preparative electrophoresis as an one-step method for purification of high molecular weight subunits of wheat glutenin
Immunological distinction between x-type and y-type high-molecular-weight glutenin subunits.
IS TRITICUM MONOCOCCUM ATOXIC IN PATIENTS WITH COELIAC DISEASE (CD)? A PILOT STUDY OF A SINGLE DOSE ADMINISTRATION .
IN VITRO ASSESSMENT OF ACETIC ACID-SOLUBLE PROTEINS (GLUTENIN) TOXICITY IN CELIAC DISEASE
Acetic-acid-soluble storage proteins from gluten of the bread wheat cv. Sprint 3 were fractionated by adsorption chromatography on 2000 \uc5 controlled-pore glass (CPG) beads, and glutenin polymers with molecular mass higher than 107 Da and free from monomeric gliadins were recovered. The glutenin polymers were found to consist of high-molecular-weight (HMW) and low-molecular-weight (LMW) glutenin subunits. Peptic-tryptic (PT) digests of glutenins were examined for their agglutination activity on human myelogenous leukemia K 562(S) cells, agglutination being strongly correlated with toxicity for the celiac intestine. The peptide fraction at a concentration of 1 g/L of culture medium was able to agglutinate 30% of K 562(S) cells, suggesting a moderate toxic effect. This toxicity may be accounted for by homologies in amino acid sequences between glutenin subunits and /\u3b2-and -gliadin
Bread-Making Quality Indices in Triticum aestivum Progenies. Implications in Breeding for Better Bread Wheat
Gli-B3/Glu-B2 encoded prolamins do not affect selected quality properties in the durum wheat cross 'Abadia' x 'Mexicali 75'
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