Modeling Hidden Nodes Collisions in Wireless Sensor Networks: Analysis Approach

This paper studied both types of collisions. In this paper, we show that advocated solutions for coping with hidden node collisions are unsuitable for sensor networks. We model both types of collisions and derive closed-form formula giving the probability of hidden and visible node collisions. To reduce these collisions, we propose two solutions. The first one based on tuning the carrier sense threshold saves a substantial amount of collisions by reducing the number of hidden nodes. The second one based on adjusting the contention window size is complementary to the first one. It reduces the probability of overlapping transmissions, which reduces both collisions due to hidden and visible nodes. We validate and evaluate the performance of these solutions through simulations

Ratiometric Electrochemical Sensor for Effective and Reliable Detection of Ascorbic Acid in Living Brains

The <i>in vivo</i> detection of ascorbic acid (AA), one of the physiologically important cerebral neurochemicals, is critical to probe and understand brain functions. Electrochemical sensors are convenient for AA detection. However, conventional electrochemical sensors usually suffer from several challenges, such as sluggish electron transfer kinetics for AA oxidation and poor reproducibility. To address these challenges, here we report ratiometric electrochemical sensors for effective and reliable detection of AA in living brains. The sensors were constructed by immobilizing preassembled thionine/Ketjen black (KB) nanocomposites onto glassy carbon (GC) electrodes or carbon fiber microelectrodes (CFMEs). The KB in the rationally functionalized nanocomposites efficiently facilitated AA oxidation at a relatively negative potential (∼−0.14 V) without particular physical or chemical pretreatment, forming the basis of selective measurement of AA. With a well-defined and reversible pair of redox wave at −0.22 V, the assembled thionine acted as an internal reference to substantially alleviate the lab-to-lab, person-to-person, and electrode-to-electrode variations. The <i>in vitro</i> experiments demonstrated that the sensors exhibited extremely high reproducibility and stability toward selective measurement of AA. More, with operational simplicity and robustness in analytical performance, the designed sensors were successfully applied to <i>in vivo</i> effectively, selectively, and reliably monitor the dynamic change of cerebral AA associated with pathological processes (i.e., salicylate-induced tinnitus as the model) in living rats’ brains. This study not only offers a new strategy for construction of ratiometric electrochemical sensors but also opens a new way for selective and reliable detection of neurochemicals for probing brain functions

Table_1_On gaps of clinical diagnosis of dementia subtypes: A study of Alzheimer’s disease and Lewy body disease.DOCX

IntroductionAlzheimer’s disease (AD) and Lewy body disease (LBD) are the two most common neurodegenerative dementias and can occur in combination (AD+LBD). Due to overlapping biomarkers and symptoms, clinical differentiation of these subtypes could be difficult. However, it is unclear how the magnitude of diagnostic uncertainty varies across dementia spectra and demographic variables. We aimed to compare clinical diagnosis and post-mortem autopsy-confirmed pathological results to assess the clinical subtype diagnosis quality across these factors.MethodsWe studied data of 1,920 participants recorded by the National Alzheimer’s Coordinating Center from 2005 to 2019. Selection criteria included autopsy-based neuropathological assessments for AD and LBD, and the initial visit with Clinical Dementia Rating (CDR) stage of normal, mild cognitive impairment, or mild dementia. Longitudinally, we analyzed the first visit at each subsequent CDR stage. This analysis included positive predictive values, specificity, sensitivity and false negative rates of clinical diagnosis, as well as disparities by sex, race, age, and education. If autopsy-confirmed AD and/or LBD was missed in the clinic, the alternative clinical diagnosis was analyzed.FindingsIn our findings, clinical diagnosis of AD+LBD had poor sensitivities. Over 61% of participants with autopsy-confirmed AD+LBD were diagnosed clinically as AD. Clinical diagnosis of AD had a low sensitivity at the early dementia stage and low specificities at all stages. Among participants diagnosed as AD in the clinic, over 32% had concurrent LBD neuropathology at autopsy. Among participants diagnosed as LBD, 32% to 54% revealed concurrent autopsy-confirmed AD pathology. When three subtypes were missed by clinicians, “No cognitive impairment” and “primary progressive aphasia or behavioral variant frontotemporal dementia” were the leading primary etiologic clinical diagnoses. With increasing dementia stages, the clinical diagnosis accuracy of black participants became significantly worse than other races, and diagnosis quality significantly improved for males but not females.DiscussionThese findings demonstrate that clinical diagnosis of AD, LBD, and AD+LBD are inaccurate and suffer from significant disparities on race and sex. They provide important implications for clinical management, anticipatory guidance, trial enrollment and applicability of potential therapies for AD, and promote research into better biomarker-based assessment of LBD pathology.</p

Investigation of Structural, Thermal, and Dynamical Properties of Pd–Au–Pt Ternary Metal Nanoparticles Confined in Carbon Nanotubes Based on MD Simulation

We apply molecular dynamics (MD) simulations to investigate structural, thermal, and dynamical properties of Pd–Au–Pt trimetallic nanoparticles confined in armchair single-walled carbon tubes ((<i>n</i>,<i>n</i>)-SWNTs). The metal–carbon interactions are described by a Lennard-Jones (LJ) potential, while the metal–metal interactions are represented by the second-moment approximation of the tight-binding (TB-SMA) potentials. Results illustrate that the confined Pd–Au–Pt metal nanoparticles appear to be of cylindrical multishelled structure, similar to those of gold (or Au–Pt) nanoparticles confined in SWNT and different from free Pd–Au–Pt nanoparticles or bulk gold. For each confined Pd–Au–Pt nanoparticle, gold atoms preferentially accumulate near the tube center, while Pt atoms preferentially distribute near the tube wall. These results are in qualitative agreement with previous observations on Au–Pt nanoparticles confined in SWNT. Importantly, Pd atoms disperse thorough the confined Pd–Au–Pt nanoparticle, which is consistent with caltalytic observations in experiment. The melting temperatures of the confined Pd–Au–Pt nanoparticles are controlled by platinum with greater cohesive energy. The melting temperatures of the confined Pd–Au–Pt nanoparticles are significantly higher than those of the free Pd–Au–Pt nanoparticles, which are caused by the confined interaction of SWNT. Some important dynamic results are obtained in terms of the classical nucleation theory

2D-Metal–Organic-Framework-Nanozyme Sensor Arrays for Probing Phosphates and Their Enzymatic Hydrolysis

The detection of phosphates and their enzymatic hydrolysis is of great importance because of their essential roles in various biological processes and numerous diseases. Compared with individual sensors for detecting one given phosphate at a time, sensor arrays are able to discriminate multiple phosphates simultaneously. Although nanomaterial-based sensor arrays have shown great promise for the discrimination of phosphates, very few of them have been explored for probing phosphates involved enzymatic hydrolysis. To fill this gap, herein we fabricated two-dimensional-metal–organic-framework (2D-MOF)-nanozyme-based sensor arrays by modulating their peroxidase-mimicking activity with various phosphates, including AMP, ADP, ATP, pyrophosphate (PPi), and phosphate (Pi). The sensor arrays were used to successfully discriminate the five phosphates not only in aqueous solutions but also in biological samples. The practical application of the sensor arrays was then validated with blind samples, where 30 unknown samples containing phosphates were accurately identified. Moreover, the sensor arrays were successfully applied to probing hydrolytic processes involving ATP and PPi that are catalyzed by apyrase and PPase, respectively. This work demonstrates a nanozyme-based sensor array as a convenient and reliable analytical platform for probing phosphates and their related enzymatic processes, which could be applied to other analytes and enzymatic reactions

Predictions of trial outcomes in the LNCGs.

<p>(A) Results of Y-maze datasets. (B) Results of U-maze datasets.</p

Method overview of construction of WNFNs of two trials of a Y-maze task dataset.

<p>(A) A rat performed the L-choice trial. (B) Raster plot of thirteen neurons recorded in this trial. (C) Pearson correlation matrix between pairs of neurons. (D) Neuronal functional network of these neurons. (E) – (H) Illustration of the procedure for construction of neuronal functional networks for the R-choice trial.</p

SDS-PAGE gel demonstrating effectiveness of P7 purification procedure.

<p>Lanes are: Marker (wide range protein ladder p7708); Control—undisrupted cells after IPTG induction; SN—supernatant after the pelleting of lysed cell’s debris; Pellet—resuspended cell debris pellet; Flow-Through—proteins unbound to Ni-NTA beads; 1^st and 2^nd Wash—proteins eluted from the Ni-NTA agarose column after 1^st and 2^nd rinses with washing buffer; Eluate—P7 protein eluted from the column.</p

Cryo TEM images of transcribing ϕ6 NCs.

<p>A) Control sample (no rNTP in transcription reaction mixture); B) NC in 4 mM of rNTP in transcription reaction mixture. Arrows in (B) indicate some of the transcribing NCs (hexagonal configuration with a lower electron density).</p

Competition between Mabs determined by ELISA.

<p>A) Single Mab (no competition); B) 6C3; C) 1C10; D) 2D11; and E) 1F11; in competition with the other three Mabs at concentrations of 1000 ng/ml. Optical Density is measured at 405 nm.</p