The weak temperature dependence of the resistance R(T) of monolayer graphene 1-3 indicates an extraordinarily high intrinsic mobility of the charge carriers. Important complications are the presence of mobile scattering centres that strongly modify charge transport, and the presence of strong mesoscopic conductance fluctuations that, in graphene, persist to relatively high temperatures 4,5 . In this Letter, we investigate the surprisingly varied changes in resistance that we find in graphene flakes as temperature is lowered below 70 K. We propose that these changes in R(T) arise from the temperature dependence of the scattered electron wave interference that causes the resistance fluctuations. Using the field effect transistor configuration, we verify this explanation in detail from measurements of R(T) by tuning to different gate voltages corresponding to particular features of the resistance fluctuations. We propose simple expressions that model R(T) at both low and high charge carrier densities.Recently, several papers have presented systematic analyses of R(T) data in graphene [1][2][3] . Morozov et al.1 ascribed the strong increase of resistivity above a temperature of 200 K to scattering by flexural phonons 6 localized in ripples in the graphene sheet. Chen et al. 2 fitted their R(T) data to the usual linear term due to scattering by acoustic phonons and Bose-Einstein functions for scattering from specific high-energy phonons. They concluded that scattering by a pair of interfacial phonons in the SiO 2 substrate 7 was the most likely origin of the increase of R(T) at high temperatures, but also noted that their resistivity increase at high T was consistent with scattering by phonons of energy 104 meV. To eliminate the role of the substrate in limiting conductivity, Bolotin et al.3 investigated a suspended graphene flake, achieving near-ballistic transport with mobility ~120,000 cm 2 /Vs at 240 K. The resistivity increased linearly from 50 K to 240 K suggesting that longitudinal acoustic phonons were the main scatterers.For low charge carrier densities near the charge neutrality point (NP), the resistivity is less well understood, generally increasing as temperature decreases but sometimes showing a decrease below 150 K 1,8 . Cho and Fuhrer 9 and Chen et al. 10 concluded that the resistance of their graphene samples near the neutrality point (NP) was governed not by the physics of the Dirac singularity but by carrier-density inhomogeneities induced by the potential of charged impurities ("puddles" of electrons and holes as imaged by Martin et al. 11 ).We have measured the resistance of monolayer graphene samples as a function of temperature and gate voltage (see Methods section for details). Figure 1 shows a typical resistance at T = 4.2 K of a portion of graphene of length 1200 nm and width 1450 nm. The resistance as a function of gate voltage V G in Figure 1a shows the usual maximum in resistance (at the NP) with charge carrier density increasing for V G on either side of the maximum. The strong irregul...
The recent surge in environmental awareness and consumer demand for stable, healthy, and safe foods has led the packaging and food sectors to focus on developing edible packaging materials to reduce waste. Edible films and coatings as a modern sustainable packaging solution offer significant potential to serve as a functional barrier between the food and environment ensuring food safety and quality. Whey protein is one of the most promising edible biopolymers in the food packaging industry that has recently gained much attention for its abundant nature, safety, and biodegradability and as an ecofriendly alternative of synthetic polymers. Whey protein isolate and whey protein concentrate are the two major forms of whey protein involved in the formation of edible films and coatings. An edible whey film is a dry, highly interacting polymer network with a three-dimensional gel-type structure. Films/coatings made from whey proteins are colorless, odorless, flexible, and transparent with outstanding mechanical and barrier properties compared with polysaccharide and other-protein polymers. They have high water vapor permeability, low tensile strength, and excellent oxygen permeability compared with other protein films. Whey protein-based films/coatings have been successfully demonstrated in certain foods as vehicles of active ingredients (antimicrobials, antioxidants, probiotics, etc.), without considerably altering the desired properties of packaging films that adds value for subsequent industrial applications. This review provides an overview of the recent advances on the formation and processing technologies of whey protein-based edible films/coatings, the incorporation of additives/active ingredients for improvement, their technological properties, and potential applications in food packaging.
Background and objectivesIntradialytic hypotension has high clinical significance. However, predicting it using conventional statistical models may be difficult because several factors have interactive and complex effects on the risk. Herein, we applied a deep learning model (recurrent neural network) to predict the risk of intradialytic hypotension using a timestamp-bearing dataset.Design, setting, participants, & measurementsWe obtained 261,647 hemodialysis sessions with 1,600,531 independent timestamps (i.e., time-varying vital signs) and randomly divided them into training (70%), validation (5%), calibration (5%), and testing (20%) sets. Intradialytic hypotension was defined when nadir systolic BP was <90 mm Hg (termed intradialytic hypotension 1) or when a decrease in systolic BP ≥20 mm Hg and/or a decrease in mean arterial pressure ≥10 mm Hg on the basis of the initial BPs (termed intradialytic hypotension 2) or prediction time BPs (termed intradialytic hypotension 3) occurred within 1 hour. The area under the receiver operating characteristic curves, the area under the precision-recall curves, and F1 scores obtained using the recurrent neural network model were compared with those obtained using multilayer perceptron, Light Gradient Boosting Machine, and logistic regression models.ResultsThe recurrent neural network model for predicting intradialytic hypotension 1 achieved an area under the receiver operating characteristic curve of 0.94 (95% confidence intervals, 0.94 to 0.94), which was higher than those obtained using the other models (P<0.001). The recurrent neural network model for predicting intradialytic hypotension 2 and intradialytic hypotension 3 achieved area under the receiver operating characteristic curves of 0.87 (interquartile range, 0.87–0.87) and 0.79 (interquartile range, 0.79–0.79), respectively, which were also higher than those obtained using the other models (P≤0.001). The area under the precision-recall curve and F1 score were higher using the recurrent neural network model than they were using the other models. The recurrent neural network models for intradialytic hypotension were highly calibrated.ConclusionsOur deep learning model can be used to predict the real-time risk of intradialytic hypotension.
The present study aimed at evaluating the utilization possibility of encapsulated probiotic Bifidobacterium longum for production of functional fermented sausages. The B. longum isolated from the feces samples of healthy Korean infants encapsulated with glycerol as a cryprotectant was used for fermented sausages production as a functional bacterial ingredient, and its effect was also compared with those inoculated with commercial starter culture (CSC). Results showed that most inoculated encapsulated B. longum (initial count, 5.88 Log CFU/g) could survive after 4 days fermentation (5.40 Log CFU/g), and approximately a half (2.83 Log CFU/g) of them survived in the products after 22 days of ripening. The products inoculated with encapsulated B. longum presented the lowest lipid oxidation level, while had higher total unsaturated fatty acid content and more desirable n-6/n-3 fatty acids than those inoculated with CSC or non-inoculated control. Moreover, the odor and taste scores in the samples made with B. longum were comparable to those in the treatment with CSC. The inoculation with the B. longum had no effects on the biogenic amine contents as well as did not cause defects in color or texture of the final products. Thus, the encapsulation could preserve the probiotic B. longum in the meat mixture, and the encapsulated B. longum could be used as a functional ingredient for production of healthier fermented meat products.
We observed the Shubnikov–de Haas and the Aharonov Bohm oscillations in a graphene nanoring structure of 1 μm in diameter and with a 125 nm channel width. We found a separation of 2ΔVg=17.5 V between electron and hole Landau levels in the plot of longitudinal resistance as a function of gate voltage and magnetic field. This separation can be understood as a result of the transport gap, ΔVt=20 V, in the density of state. The Aharonov Bohm effect was observed in magnetoconductance with poor visibility because of the short phase coherence length of the graphene nanoring structure.
This study aimed to examine the quality characteristics of fermented milk, Mozzarella cheese, and Gouda cheese from Jersey and Holstein milk. The fermented milk, Mozzarella cheese, and Gouda cheese made from the Jersey breed exhibited higher fat, calcium, and phosphorous contents than those from the Holstein breed. The proportion of saturated fatty acids such as palmitic acid and stearic acid was higher in dairy products made from Jersey than those made from Holstein, as was the component ratio of unsaturated fatty acids containing oleic acid and linoleic acid. In the sensory evaluations of fermented milk and Mozzarella cheese, the preference scores of products from Jersey were lower in color, flavor, texture, taste, and general preference than those from Holstein. In terms of sensory preference, it is considered that Jersey milk may be more appropriate for ripened cheese than fermented milk and fresh cheese. Therefore, Jersey milk is expected to contribute to the diversification of dairy products and to provide consumers with high quality nutrition.
Objective: This study was conducted to determine the composition and diversity of the fungal flora at various control points in cheese ripening rooms of 10 dairy farms from six different provinces in the Republic of Korea.Methods: Floor, wall, cheese board, room air, cheese rind and core were sampled from cheese ripening rooms of ten different dairy farms. The molds were enumerated using YM petrifilm, while isolation was done on yeast extract glucose chloramphenicol agar plates. Morphologically distinct isolates were identified using sequencing of internal transcribed spacer region.Results: The fungal counts in 8 out of 10 dairy farms were out of acceptable range, as per hazard analysis critical control point regulation. A total of 986 fungal isolates identified and assigned to the phyla Ascomycota (14 genera) and Basidiomycota (3 genera). Of these <i>Penicillium</i>, <i>Aspergillus</i>, and <i>Cladosporium</i> were the most diverse and predominant. The cheese ripening rooms was overrepresented in 9 farms by <i>Penicillium</i> (76%), while <i>Aspergillusin</i> a single farm. Among 39 species, the prominent members were <i>Penicillium commune</i>, <i>P. oxalicum</i>, <i>P. echinulatum</i>, and <i>Aspergillus versicolor</i>. Most of the mold species detected on surfaces were the same found in the indoor air of cheese ripening rooms.Conclusion: The environment of cheese ripening rooms persuades a favourable niche for mold growth. The fungal diversity in the dairy farms were greatly influenced by several factors (exterior atmosphere, working personnel etc.,) and their proportion varied from one to another. Proper management of hygienic and production practices and air filtration system would be effective to eradicate contamination in cheese processing industries.
Gouda cheese, one of most popular cheeses in the Korea, has been produced from only pasteurized milk in Korean dairy farms. Recently, it has become legally possible to produce ripened cheese manufactured with raw milk in Korea. In the present study, we investigated the physico-chemical and microbiological characteristics of Gouda cheese manufactured with raw (R-GC) or pasteurized milk (P-GC) during manufacturing and ripening. Particularly, this study characterized the bacterial community structure of two cheese types, which are produced without pasteurization during ripening based on next generation sequencing of 16S rRNA gene amplicons. During ripening, protein and fat content increased slightly, whereas moisture content decreased in both P-GC and R-GC. At the 6 wk of ripening, R-GC became softer and smoother and hence, the values of hardness and gumminess, chewiness in R-GC was lower than that of P-GC. Metagenomic analysis revealed that the bacterial genera used a starter cultures, namely Lactococcus and Leuconostoc were predominant in both P-GC and R-GC. Moreover, in R-GC, the proportion of coliform bacteria such as Escherichia , Leclercia , Raoultella , and Pseudomonas were detected initially but not during ripening. Taken together, our finding indicates the potential of manufacturing with Gouda cheese from raw milk and the benefits of next generation sequencing for microbial community composition during cheese ripening.
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