ECL sensor for selective determination of citrate ions as a prostate cancer biomarker using polymer of intrinsic microporosity-1 nanoparticles/nitrogen-doped carbon quantum dots

Urine citrate analysis is relevant in the screening and monitoring of patients with prostate cancer and calcium nephrolithiasis. A sensitive, fast, easy, and low-maintenance electrochemiluminescence (ECL) method with conductivity detection for the analysis of citrate in urine is developed and validated by employing polymer of intrinsic microporosity-1 nanoparticles/nitrogen-doped carbon quantum dots (nano-PIM-1/N-CQDs). Using optimum conditions, the sensor was applied in ECL experiments in the presence of different concentrations of citrate ions. The ECL signals were quenched gradually by the increasing citrate concentration. The linear range of the relationship between the logarithm of the citrate concentration and ΔECL (ECL of blank − ECL of sample) was obtained between 1.0 × 10 −7 M and 5.0 × 10 −4 M. The limit of detection (LOD) was calculated to be 2.2 × 10 −8 M (S/N = 3). The sensor was successfully applied in real samples such as human serum and patient urine. Graphical abstract: [Figure not available: see fulltext.].</p

Smartphone Overuse from Iranian University Students’ Perspective: A Qualitative Study

Background: Smartphone usage has increasing during recent years. Since its excessive use can have negativeconsequences, it is important to know how users use it and become dependent on it. This study was aimed atexploring how university students use their phones, how they depend on them, and the possibleconsequences of overusing them.Methods: This study was conducted using a qualitative design and with a thematic analysis method. Datawere collected using 3 focus group discussions regarding experiences of using smartphones among 22smartphone owners who reported smartphone overuse. They were chosen through snowball sampling at aUniversity of Medical Sciences in Tehran (Iran).Findings: Based on the analysis, the 3 categories of process usage (sub-categories: doing daily routines,information seeking, to take a picture or video, entertainment, academic work, making money, to escapereal-life, and passing the time), social usage (sub-categories: relationship with family, relationship withfriends, interact with the opposite gender, to be seen and heard, approval seeking, and free expression), anddisadvantages (sub-categories: interference with other essential activities, decreased face-to-facecommunications, overdependence, automatic use, loss of sense of time, stress, fatigue, sleep disturbances,physical inactivity, eye problems, high bills, and distraction) were developed.Conclusion: In this research, participants mentioned various uses of their smartphones that enable them tomeet their personal needs and, in spite of the negative consequences of its overuse, cause them to continue touse it. Some uses seem to be affected by environmental and cultural conditions

Polymers of Intrinsic Microporosity (PIMs) in Sensing and in Electroanalysis

Polymers of intrinsic microporosity (PIMs) provide high surface area materials (typically 1000 m2 g-1 apparent BET surface area) that are processable from organic solvents to give glassy films or composite coatings. Multi-functionality for sensing with these materials is achieved (i) based on the polymer backbone itself being fluorescent or chemically active or (ii) based on guest species (chromophores, nano-catalysts, nano-photo-catalysts, etc.) that are readily embedded into PIMs and accessible through micropores in the polymer host. The ease of forming uniform microporous films or composite films is linked to molecular rigidity and highlighted here for sensing/electroanalytical applications

A GPU-based Correlator X-engine Implemented on the CHIME Pathfinder

We present the design and implementation of a custom GPU-based compute cluster that provides the correlation X-engine of the CHIME Pathfinder radio telescope. It is among the largest such systems in operation, correlating 32,896 baselines (256 inputs) over 400MHz of radio bandwidth. Making heavy use of consumer-grade parts and a custom software stack, the system was developed at a small fraction of the cost of comparable installations. Unlike existing GPU backends, this system is built around OpenCL kernels running on consumer-level AMD GPUs, taking advantage of low-cost hardware and leveraging packed integer operations to double algorithmic efficiency. The system achieves the required 105TOPS in a 10kW power envelope, making it among the most power-efficient X-engines in use today.Comment: 6 pages, 5 figures. Accepted by IEEE ASAP 201

Calibrating CHIME, A New Radio Interferometer to Probe Dark Energy

The Canadian Hydrogen Intensity Mapping Experiment (CHIME) is a transit interferometer currently being built at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC, Canada. We will use CHIME to map neutral hydrogen in the frequency range 400 -- 800\,MHz over half of the sky, producing a measurement of baryon acoustic oscillations (BAO) at redshifts between 0.8 -- 2.5 to probe dark energy. We have deployed a pathfinder version of CHIME that will yield constraints on the BAO power spectrum and provide a test-bed for our calibration scheme. I will discuss the CHIME calibration requirements and describe instrumentation we are developing to meet these requirements

Canadian Hydrogen Intensity Mapping Experiment (CHIME) Pathfinder

A pathfinder version of CHIME (the Canadian Hydrogen Intensity Mapping Experiment) is currently being commissioned at the Dominion Radio Astrophysical Observatory (DRAO) in Penticton, BC. The instrument is a hybrid cylindrical interferometer designed to measure the large scale neutral hydrogen power spectrum across the redshift range 0.8 to 2.5. The power spectrum will be used to measure the baryon acoustic oscillation (BAO) scale across this poorly probed redshift range where dark energy becomes a significant contributor to the evolution of the Universe. The instrument revives the cylinder design in radio astronomy with a wide field survey as a primary goal. Modern low-noise amplifiers and digital processing remove the necessity for the analog beamforming that characterized previous designs. The Pathfinder consists of two cylinders 37\,m long by 20\,m wide oriented north-south for a total collecting area of 1,500 square meters. The cylinders are stationary with no moving parts, and form a transit instrument with an instantaneous field of view of $\sim$100\,degrees by 1-2\,degrees. Each CHIME Pathfinder cylinder has a feedline with 64 dual polarization feeds placed every $\sim$30\,cm which Nyquist sample the north-south sky over much of the frequency band. The signals from each dual-polarization feed are independently amplified, filtered to 400-800\,MHz, and directly sampled at 800\,MSps using 8 bits. The correlator is an FX design, where the Fourier transform channelization is performed in FPGAs, which are interfaced to a set of GPUs that compute the correlation matrix. The CHIME Pathfinder is a 1/10th scale prototype version of CHIME and is designed to detect the BAO feature and constrain the distance-redshift relation.Comment: 20 pages, 12 figures. submitted to Proc. SPIE, Astronomical Telescopes + Instrumentation (2014

Interfacial electron shuttling processes across Kolliphor®EL monolayer grafted electrodes

Covalently grafted Kolliphor®EL (a poly-ethylene-glycol based "transporter molecule" for hydrophobic water-insoluble drugs; MW ca. 2486; diameter ca. 3-5 nm) at the surface of a glassy carbon electrode strongly affects the rate of electron transfer for aqueous redox systems such as Fe(CN)63-/4-. XPS data confirm mono-layer grafting after electrochemical anodisation in pure Kolliphor®EL. Based on voltammetry and impedance measurements, the charge transfer process for the Fe(CN)63-/4- probe molecule is completely blocked after Kolliphor®EL grafting and in the absence of a "guest". However, in the presence of low concentrations of suitable ferrocene derivatives as "guests", mediated electron transfer across the mono-layer via a "shuttle mechanism" is observed. The resulting amplification of the ferrocene electroanalytical signal is investigated systematically and compared for 5 ferrocene derivatives. The low concentration electron shuttle efficiency decreases in the sequence dimethylaminomethyl-ferrocene &gt; n-butyl-ferrocene &gt; ferrocene-dimethanol &gt; ferrocene-acetonitrile &gt; ferrocene-acetic acid.</p