A Fast Data Structure for Anagrams

In this paper, we are presenting a data structure, which stores the given dictionary data in a hash table called PRIME , by using fundamental theorem on Arithmetic to generate a key for each dictionary word, and stores the word in the hash table based on the key. As compared to tree-based techniques PRIME table generates anagram for the given random word in O(1) time, time to construct a PRIME table depends on the number of words in the dictionary. If dictionary has ‘n’ words then the time to develop the PRIME table is O(n). Categories and Subject descriptors: Problem solving, search and control methods

High pressure and ultrasonification technologies for manufacturing yogurt

Nonthermal processing is a rapidly growing field of research and industry use for production of safe foods and modification and/or improvement of quality. It is expected that this trend will grow, as consumers want minimally processed foods of natural flavor that are free from additives and preservatives. High hydrostatic pressure (HHP) and ultrasonification are two promising nonthermal processing technologies studied in this research for manufacturing low fat probiotic yogurt and improving the viability of probiotics in yogurt. Yogurt was manufactured using heat, HHP, and a combined treatment of HHP and heat. The effect of ultrasonification on the physicochemical, rheological, textural, and microstructure of low fat probiotic yogurt were studied. The combined application of HHP and thermal treatment resulted in yogurt gels with improved physicochemical characteristics and water holding capacity over heat or HHP alone. The HHP and heat combined treatment resulted in yogurt gels with improved consistency indices over gels obtained from thermally treated milk. The starter and inoculation rate that provideddifferent fermentation pathways also affected the consistency index and texture properties. Rheological behavior differences of yogurts varied according to the treatment used, and were attributed to structural phenomena of casein micelles. The combined HHP and heat milk treatments exhibited small rounded micelles that tended to fuse and form small irregular aggregates in association with clumps of dense amorphous material, which resulted in improved gel texture and viscosity. Ultrasonification was used to rupture yogurt bacteria to improve the viability of probiotics in yogurt. The probiotics grew better in sonicated culture yogurt compared to unsonicated culture yogurt, indicating increased availability of nutrients for the probiotics, which can be attributed to β-galactosidase availability. Sonicated starter yogurts presented lower syneresis compared to the control yogurts during storage. Ultrasonification improved the viability of probiotics by two log cycles at the end of storage period. The reduction of viability beyond the 24th day can be attributed to the lowering of pH. Overall, the results suggest that ultrasonification can possibly improve the viability of probiotics and quality of yogurt. Finally, both HHP and ultrasonification are potentially promising nonthermal processing technologies that can be selected for manufacturing yogurt to improve quality and viability of probiotics

Spin transport in graphene - hexagonal boron nitride van der Waals heterostructures

De huidige micro-elektronicatechnologie gebruikt de ladingseigenschappen van een elektron voor informatieverwerking. Om de uitdagingen, zoals de vermogensdissipatie en downscaling van de elektronische apparaten te overwinnen, onderzoekt het vakgebied spintronica (spin-gebaseerde elektronica) een extra intrinsieke eigenschap van het elektron, spin genoemd, welke een puur kwantummechanische eigenschap is. Grafeen, een één-atomige tweedimensionale laag koolstofatomen, is de laatste tien jaar ontstaan als een veelbelovend materiaal voor spintronica-toepassingen. Het onderzoek dat in dit proefschrift gepresenteerd wordt, behandelt de uitdagingen in grafeen-spintronica als gevolg van het onderliggende substraat, onzuiverheden op het oppervlak van grafeen en de kwaliteit van de ferromagnetische tunnelingcontacten. Hiervoor introduceren we een nieuwe device-geometrie waarbij grafeen volledig is ingekapseld tussen twee hexagonale boornitride (hBN) lagen. We laten zien dat hBN een schone tunnelbarrière-grafeeninterface biedt die lange afstand-spintransport in grafeen mogelijk maakt. Verder laten we zien dat het mogelijk is om spin-injectie en detectiepolarisaties tot ± 100% te bereiken en een unieke tekeninversie van spinsignalen te maken door toepassing van een elektrisch veld over de ferromagnetische tunnelingcontacten. We hebben ook grootschalige, met chemische dampafzetting (CVD) gekweekte hBN als tunnelbarrières gebruikt en onze studie wijst op het belang van de kwaliteit en de kristallografische oriëntatie van hBN bij het bepalen van de tunnelingkenmerken. De resultaten die gepresenteerd worden in dit proefschrift vertegenwoordigen belangrijke ontwikkelingen in het begrijpen van de aard van spintransport in grafeen en spin-injectie via hBN-barrieres. Dit inzicht zal zeker helpen bij het overwinnen van de uitdagingen bij het realiseren van praktische spintronische devices gebaseerd op grafeen-hBN-van der Waals-heterostructuren

Electrical spin injection, transport, and detection in graphene-hexagonal boron nitride van der Waals heterostructures: progress and perspectives

The current research in graphene spintronics strives for achieving a long spin lifetime, and efficient spin injection and detection in graphene. In this article, we review how hexagonal boron nitride (hBN) has evolved as a crucial substrate, as an encapsulation layer, and as a tunnel barrier for manipulation and control of spin lifetimes and spin injection/detection polarizations in graphene spin valve devices. First, we give an overview of the challenges due to conventional SiO$_2$ substrate for spin transport in graphene followed by the progress made in hBN based graphene heterostructures. Then we discuss in detail the shortcomings and developments in using conventional oxide tunnel barriers for spin injection into graphene followed by introducing the recent advancements in using the crystalline single/bi/tri-layer hBN tunnel barriers for an improved spin injection and detection which also can facilitate two-terminal spin valve and Hanle measurements, at room temperature, and are of technological importance. A special case of bias induced spin polarization of contacts with exfoliated and chemical vapour deposition (CVD) grown hBN tunnel barriers is also discussed. Further, we give our perspectives on utilizing graphene-hBN heterostructures for future developments in graphene spintronics.Comment: Review, Author submitted manuscript - draft; 25 pages, 8 figure