Comparison of arterial transit times estimated using arterial spin labeling

Objective  

To compare arterial transit time estimates from two efficient transit time mapping techniques using arterial spin labeling (ASL)—flow encoded arterial spin tagging (FEAST) and Look-Locker ASL (LL-ASL). The effects of bipolar gradients and label location were investigated.     

Tight Bounds for Unconditional Authentication Protocols in the Manual Channel and Shared Key Models

We address the message authentication problem in two seemingly different communication models. In the first model, the sender and receiver are connected by an insecure channel and by a low-bandwidth auxiliary channel, that enables the sender to ldquomanuallyrdquo authenticate one short message to the receiver (for example, by typing a short string or comparing two short strings). We consider this model in a setting where no computational assumptions are made, and prove that for any there exists a -round protocol for authenticating -bit messages, in which only bits are manually authenticated, and any adversary (even computationally unbounded) has probability of at most to cheat the receiver into accepting a fraudulent message. Moreover, we develop a proof technique showing that our protocol is essentially optimal by providing a lower bound of on the required length of the manually authenticated string. The second model we consider is the traditional message authentication model. In this model, the sender and the receiver share a short secret key; however, they are connected only by an insecure channel. We apply the proof technique above to obtain a lower bound of on the required Shannon entropy of the shared key. This settles an open question posed by Gemmell and Naor (Advances in Cryptology-CRYPTO '93, pp. 355-367, 1993). Finally, we prove that one-way functions are necessary (and sufficient) for the existence of protocols breaking the above lower bounds in the computational setting.     

Sensitivity of trigate MOSFETs to random dopant induced threshold voltage fluctuations

In this paper, we investigate random doping fluctuation effects in trigate SOI MOSFETs by solving the three-dimensional (3D) Poisson, drift-diffusion and continuity equations numerically. A single doping impurity atom is introduced in the undoped channel region of the device and the resulting shift of threshold voltage is measured from the simulated I–V characteristics. This enables the derivation of the threshold voltage shift (ΔV_TH) for any arbitrary location of the doping atom in the transistor. Based on an analysis of a sub-20 nm trigate MOSFET device, we find that the typical variation of V_TH per doping atom is a few tens of mV. Inversion-mode (IM) trigate devices are more sensitive to the doping fluctuation effects than accumulation-mode (AM) devices. The threshold voltage shift arising from doping fluctuations is maximum when the doping atom is near the center of the channel region, which means the original SOI film doping, the random contamination effects or any other impurity doping in the channel region is more important than atoms introduced in the channel by the S/D implantation process for sub-20 nm transistors.     

Coralline Skeleton Biomaterial Reduces Phagocytosis in Mouse Blood in vitro

Inflammatory and immunogenic response to foreign bodies presents a challenge in the use of biomaterials as implants for tissue restoration. Therefore, there is a need to understand the interactions between such implants and the blood. One such material, currently in clinical use for bone replacement in humans, is the skeleton of corals, in the form of crystalline aragonite. This biomaterial has been shown to impart a protective and supportive influence on several types of cells ex vivo. The carbonate skeleton activates secretion in phagocytes in vitro, however its effects on these cells in the blood, and on the process of phagocytosis itself, remain unknown. Using 1–500 μm particles of coral skeleton, we show that these particles bind blood proteins and alter the leukocyte population, reducing the proportion of granulocytes by more than 3-fold with no effect on the proportion of monocytes. In addition, the presence of coral skeleton in the blood causes a reduction in phagocytosis. Specifically, we observed a decrease in the percentage of phagocytic cells by 27 % in the granulocytes and by 73 % in monocyte family, as well as a 41.6 % reduction in the MFI of granulocytes, but with no such effect on monocytes. Taken together, the results suggest that the coral skeleton biomaterial may act as a strong, promotive scaffold for tissue regeneration due to its ability to reduce its rejection by inflammatory reactions such as phagocytosis.     

Cold plasma for the disinfection of industrial food-contact surfaces: An overview of current status and opportunities

Food safety is the primary goal for food and drink manufacturers. Cleaning and disinfection practices applied to the processing environment are vital to maintain this safety; yet, current approaches can incur costly downtime and the potential for microorganisms to grow and establish, if not effectively removed. For that reason, manufacturers are seeking nonthermal, online, and continuous disinfection processes to control the microbial levels within the processing environment. One such emerging technique, with great potential, is cold atmospheric pressure plasma (CAP). This review presents the latest advances and challenges associated with CAP-based technologies for the decontamination of surfaces and equipment found within the food-processing environment. It provides a detailed overview of the technology and a comprehensive analysis of the many CAP-based antimicrobial studies on food-contact surfaces and materials. As CAP is considered an emerging technique, many of the recent studies are still in the preliminary stages, with results obtained under widely different conditions. This lack of cohesive information and an inability to directly compare CAP systems has greatly impeded technological development. The review further explores the challenge of scaling CAP technology to meet industry needs, considering aspects such as regulatory constraints, environmental credentials, and cost of use. Finally, a discussion is presented on the future outlook for CAP technology in this area, identifying key challenges that must be addressed to promote industry uptake.     

Electrical Characterization of Individual Cesium Lead Halide Perovskite Nanowires Using Conductive AFM

Perovskite nanostructures have attracted much attention in recent years due to their suitability for a variety of applications such as photovoltaics, light-emitting diodes (LEDs), nanometer-size lasing, and more. These uses rely on the conductive properties of these nanostructures. However, electrical characterization of individual, thin perovskite nanowires has not yet been reported. Here, conductive atomic force microscopy characterization of individual cesium lead halide nanowires is presented. Clear differences are observed in the conductivity of nanowires containing only bromide and nanowires containing a mixture of bromide and iodide. The differences are attributed to a higher density of crystalline defects, deeper trap states, and higher inherent conductivity for nanowires with mixed bromide–iodide content.     

A Gel‐Based Model of Selective Cell Motility: Implications for Cell Sorting,Diagnostics, and Screening

The ability to precisely control cell‐loaded material systems is essential for in vitro testing of novel therapeutics poised to advance to clinic. In this report, unique patterns of cell migration are devised into an in vitro gel‐in‐gel model for the purpose of obtaining cell response data to potentially therapeutic chemical agonists. The model consists of co‐cultures in a cell‐loaded microgel invading an acellular “sorting” gel. Material properties including biophysical and chemical compositions of the sorting gel are carefully controlled to guide a desired cell‐specific behavior, leading to massive tumor cell invasion by amoeboid migration mechanisms. Optical transparency enables straightforward and high‐throughput measurements of outgrowth response in the presence of either chemical and photoradiation therapy. Important dosing and drug sensitivity information are obtained with the gel‐in‐gel model using no more than a light microscope, without further need for arduous genomic or proteomic screening of the tissue samples.     

High‐TC Interfacial Ferromagnetism in SrMnO3/LaMnO3 Superlattices

Heterostructures of strongly correlated oxides demonstrate various intriguing and potentially useful interfacial phenomena. LaMnO₃/SrMnO₃ superlattices are presented showcasing a new high‐temperature ferromagnetic phase with Curie temperature, T_C ≈360 K, caused by electron transfer from the surface of the LaMnO₃ donor layer into the neighboring SrMnO₃ acceptor layer. As a result, the SrMnO₃ (top)/LaMnO₃ (bottom) interface shows an enhancement of the magnetization as depth‐profiled by polarized neutron reflectometry. The length scale of charge transfer, λ_TF ≈2 unit cells, is obtained from in situ growth monitoring by optical ellipsometry, supported by optical simulations, and further confirmed by high resolution electron microscopy and spectroscopy. A model of the inhomogeneous distribution of electron density in LaMnO₃/SrMnO₃ layers along the growth direction is concluded to account for a complex interplay between ferromagnetic and antiferromagnetic layers in superlattices.     

Highly Conductive Thin Uniform Gold‐Coated DNA Nanowires

Over the past decades, DNA, the carrier of genetic information, has been used by researchers as a structural template material. Watson‐Crick base pairing enables the formation of complex 2D and 3D structures from DNA through self‐assembly. Various methods have been developed to functionalize these structures for numerous utilities. Metallization of DNA has attracted much attention as a means of forming conductive nanostructures. Nevertheless, most of the metallized DNA wires reported so far suffer from irregularity and lack of end‐to‐end electrical connectivity. An effective technique for formation of thin gold‐coated DNA wires that overcomes these drawbacks is developed and presented here. A conductive atomic force microscopy setup, which is suitable for measuring tens to thousands of nanometer long molecules and wires, is used to characterize these DNA‐based nanowires. The wires reported here are the narrowest gold‐coated DNA wires that display long‐range conductivity. The measurements presented show that the conductivity is limited by defects, and that thicker gold coating reduces the number of defects and increases the conductive length. This preparation method enables the formation of molecular wires with dimensions and uniformity that are much more suitable for DNA‐based molecular electronics.