Probe Volume Research Articles

Compton Scattering Imaging for in-Situ and Operando Analyses of Working Batteries

An ever-increasing demand for high-performance batteries has spurred a research activity in search of proven, in-situ and operando techniques for monitoring the electrochemical reactions and structural changes that occur inside a working battery. Here we propose an X-ray imaging technique based on synchrotron X-ray Compton scattering and demonstrate its application to batteries. The technique uses monochromatic X-rays as the probe, and detects Compton scattered X-rays from a certain volume element inside a battery. Both X-rays are higher than 100 keV with high penetration power into materials and X-ray Compton scattering is sensitive to the constituent elements [1], which enables the electrochemical and structural analyses under the in-situ and operando condition. In this paper, we present the outline of Compton scattering imaging (CSI), its application to a commercial coin battery and the future direction of this technique.The CSI technique provides three-dimensional images of the electron density distribution of an object without the need of observations from all surrounding directions [2, 3]. Because of high sensitivity to low-Z element materials, the technique with a conventional X-ray source or gamma-ray source has been used in the medical field and in the food and agricultural industries. The drawbacks of the technique were the relatively low counting rate and large probing volume element, but these have been overcome by the use of synchrotron X-rays and related focusing X-ray optics [4]. Synchrotron radiation based CSI (SR-CSI) has now been developed to such that it can provide the dynamic images of the electron density distribution inside a working battery.As a demonstration, we have measured the intensity of Compton scattered X-rays from the discharging coin cell (CR2032) as a function of one-dimensional position inside the cell and discharging time (see Figure). The position-time intensity map captures the migration of lithium ions in the positive electrode and reveals the change in position of the separator due to the volume expansion of the electrode. The experiment was performed at the BL08W beamline of SPring-8, Japan. The incident 115 keV X-ray beams with a size of 20μm(v)x500μm(h) were guided to the coin cell and Compton scattered X-rays from a volume element inside the cell were collected with a Ge solid state detector at a scattering angle of 90 degrees. Placing a slit with a width of 500μm in front of the detector, the volume element at each position was 20μmx500μmx500μm. This demonstration is a critical step for further development.We are developing the SR-CSI technique for larger Li batteries such as those mounted in plug-in hybrid electric vehicles or in electric vehicles. The challenges are to reduce the probing volume element and to enhance the detection efficiency. We will present the future direction along this line. This work is supported by the Development of Systems and Technology for Advanced Measurement and Analysis program under Japan Science and Technology Agency.[1] M. J. Cooper, Rep. Prog. Phys. 48 (1985) 415-481.[2] J. M. Sharaf, Applied Radiation and Isotopes, 54(2001) 801-809.[3] G. Harding and E. Harding, Applied Radiation and Isotpes, 68(2010) 993-1005.[4] A. Andrejczuk, M. Nagamine, Y. Sakurai and M. Itou, J. Synchrotron Rad. 21(2014)57-60.

Terahertz probe of individual subwavelength objects in a water environment

Terahertz (THz) spectroscopy and imaging have been heralded for some time as potentially revolutionary techniques for biomedical applications. Label-free detection of molecules and recognition of molecular events are often mentioned as the most exciting possibilities. A crucial practical goal, however, is the ability to perform such measurements on tiny amounts of biological fluids or even on individual organic structures. Living cells, for instance, have diameters at most of some tens of micrometers, i.e. at least λ/10 even for few-THz radiation. Furthermore, all analyses relevant for a biological perspective must be performed in a water environment, which presents a strong absorption across the whole THz spectral range, severely limiting the penetration of the electromagnetic field. Here, it is shown how both issues can be overcome with a lab-on-a-chip approach based on a microfluidic platform coupled to a plasmonic antenna. Using a quantum cascade laser as THz illumination source, liquid volumes down to the picoliter range are probed, and direct operation on individual 10-µm diameter microparticles flowing in water is shown. The present demonstration opens the way to the development of THz biosensing of individual living cells and small probe volumes.

The softening of human bladder cancer cells happens at an early stage of the malignancy process.

Various studies have demonstrated that alterations in the deformability of cancerous cells are strongly linked to the actin cytoskeleton. By using atomic force microscopy (AFM), it is possible to determine such changes in a quantitative way in order to distinguish cancerous from non-malignant cells. In the work presented here, the elastic properties of human bladder cells were determined by means of AFM. The measurements show that non-malignant bladder HCV29 cells are stiffer (higher Young’s modulus) than cancerous cells (HTB-9, HT1376, and T24 cell lines). However, independently of the histological grade of the studied bladder cancer cells, all cancerous cells possess a similar level of the deformability of about a few kilopascals, significantly lower than non-malignant cells. This underlines the diagnostic character of stiffness that can be used as a biomarker of bladder cancer. Similar stiffness levels, observed for cancerous cells, cannot be fully explained by the organization of the actin cytoskeleton since it is different in all malignant cells. Our results underline that it is neither the spatial organization of the actin filaments nor the presence of stress fibers, but the overall density and their 3D-organization in a probing volume play the dominant role in controlling the elastic response of the cancerous cell to an external force.

Lithographically-fabricated channel arrays for confocal x-ray fluorescence microscopy and XAFS

Confocal X-ray Fluorescence Microscopy (CXRF) employs overlapping focal regions of two x-ray optics—a condenser and collector—to directly probe a 3D volume. The minimum-achievable size of this probe volume is limited by the collector, for which polycapillaries are generally the optic of choice. Recently, we demonstrated an alternative collection optic for CXRF, consisting of an array of micron-scale collimating channels, etched in silicon, and arranged like spokes of a wheel directed towards a single source position. The optic, while successful, had a working distance of only 0.2 mm and exhibited relatively low total collection efficiency, limiting its practical application. Here, we describe a new design in which the collimating channels are formed by a staggered array of pillars whose side-walls taper away from the channel axis. This approach improves both collection efficiency and working distance, while maintaining excellent spatial resolution. We illustrate these improvements with confocal XRF data obtained at the Cornell High Energy Synchrotron Source (CHESS) and the Advanced Photon Source (APS) beamline 20-ID-B.

CFD application to advanced design for high efficiency spacer grid

Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased.The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity measurement using the rod LDV, CFD methodology that predicts flow field in a PWR fuel precisely has been developed and design information that utilizes for high efficiency spacer grid has been obtained.The new spacer grid that designed using the CFD methodology has almost equal pressure loss and increased CHF performance compared to the current grid. The result of the study indicates that the CFD simulation can play a significant role in designing high efficiency PWR spacer grids.

The Number of Accumulated Photons and the Quality of Stimulated Emission Depletion Lifetime Images

Time binning is used to increase the number of photon counts in the peak channel of stimulated emission depletion fluorescence lifetime decay curves to determine how it affects the resulting lifetime image. The fluorescence lifetime of the fluorophore, Alexa Fluor 594 phalloidin, bound to F-actin is probed in cultured S2 cells at a spatial resolution of ~40 nm. This corresponds to a 10-fold smaller probe volume compared to confocal imaging, and a reduced number of photons contributing to the signal. Pixel-by-pixel fluorescence lifetime measurements and error analysis show that an average of 40 ± 30 photon counts in the peak channel with a signal-to-noise ratio of 20 is enough to calculate a reliable fluorescence lifetime from a single exponential fluorescence decay. No heterogeneity in the actin cytoskeleton in different regions of the cultured cells was measured in the 40-400 nm spatial regime.

Dual Focus Fluorescence Cross-Correlation Spectroscopy for the Investigation of Biomolecule Folding and Binding in Flowing Liquids

Fluorescence correlation spectroscopy measures the time constants for rate processes giving rise to fluorescence intensity fluctuations observed from one or more microscopic sub-volumes of a nanomolar aqueous solution containing the biomolecules of interest. In our approach, the analyte molecules flow through an electrophoresis capillary under the influence of pressure driven flow or electrophoretic flow and are probed by two spatially offset probe volumes in such a way that the molecules flow sequentially from one probe volume to the next. Fluorescence fluctuations are analyzed from each probe volume independently using autocorrelation analysis, and from the two spatially offset probe volumes using cross-correlation analysis. In this way, we are able to resolve fluorescence fluctuation time constants arising from diffusion, flow, triplet blinking, and conformational fluctuations. Conformational fluctuations are monitored by quenching and unquenching of dye-quencher molecules attached to DNA or RNA hairpin structures and probe the folding and unfolding kinetics of the hairpins. In this presentation, we will discuss recent results that show how base stacking within the loop region of the DNA and RNA hairpins alters the kinetics and thermodynamic stability of the hairpins. We will also discuss binding and unbinding of counterions to individual nucleotides as they flow through the capillary under the influence of an applied electric field. Emphasis will be placed on how the desired information can be extracted using our unique approach to fluorescence correlation spectroscopy.

A review of turbulence measurements using ground-based wind lidars

Abstract. A review of turbulence measurements using ground-based wind lidars is carried out. Works performed in the last 30 yr, i.e., from 1972–2012 are analyzed. More than 80% of the work has been carried out in the last 15 yr, i.e., from 1997–2012. New algorithms to process the raw lidar data were pioneered in the first 15 yr, i.e., from 1972–1997, when standard techniques could not be used to measure turbulence. Obtaining unfiltered turbulence statistics from the large probe volume of the lidars has been and still remains the most challenging aspect. Until now, most of the processing algorithms that have been developed have shown that by combining an isotropic turbulence model with raw lidar measurements, we can obtain unfiltered statistics. We believe that an anisotropic turbulence model will provide a more realistic measure of turbulence statistics. Future development in algorithms will depend on whether the unfiltered statistics can be obtained without the aid of any turbulence model. With the tremendous growth of the wind energy sector, we expect that lidars will be used for turbulence measurements much more than ever before.

Criminal Justice Processing and the Social Matrix of Adversity

A it is by now well known that incarceration in America went off the rails in the latter quarter of the twentieth century, the magnitude and rapidity of the shift took most scholars by surprise at the time. Indeed, virtually the same year that blumstein and Cohen (1973) published their thesis asserting “the stability of punishment,” prison gates across the country seemed to swing wide open to accommodate a surge of new entrants. It took a while, but the unprecedented rise of imprisonment triggered considerable attention within the academy. Something of a consensus seems to have formed—on balance, there is little evidence that the increase in imprisonment has achieved much good. It is true that crime rates have declined at a historic pace in many cities and incarceration no doubt played a role, but the marginal effects of high rates of imprisonment especially from the 1990s onward appear to be modest at best (Raphael and Stoll 2013, 236). Many scholars go further and claim that high rates of incarceration have exacerbated inequality (e.g., in educational attainment and employment) and inflicted outright harm, especially among African Americans, who have experienced the deepest penetration of imprisonment’s reach (Pettit and Western 2004). the editors of this volume of The ANNALS probe what is less well known about America’s

Space-charge limits of ion sensitive probes

Ion sensitive probes (ISPs) are used to measure ion temperature and plasma potential in magnetized plasmas. Their operation relies on the difference in electron and ion Larmor radii to preferentially collect the ion species on a recessed electrode. Because of their simple two-electrode construction and optimal geometry for heat flux handling they are an attractive probe to use in the high heat flux boundary of magnetic confinement fusion experiments. However, the integrity of its measurements is rarely, if ever, checked under such conditions. Recent measurements with an ISP in the Alcator C-Mod tokamak have shown that its ion current is space-charge limited and thus its current–voltage (I–V) response does not contain information on the ion temperature. We numerically solve a 1D Vlasov–Poisson model of ion collection to determine how much bias is needed to overcome space-charge effects and regain the classic I–V characteristic with an exponential decay. Prompted by the observations of space charge in C-Mod, we have performed a survey of ISP measurements reported in the literature. Evidence of space-charge limited current collection is found on many probes, with few authors noting its presence. Some probes are able to apparently exceed the classic 1D space-charge limit because electrons can E × B drift into the probe volume, partially reducing the net ion charge; it is argued that this does not, however, change the basic problem that space charge compromises the measurement of ion temperature. Guidance is given for design of ISPs to minimize the effects of space charge.

Validating excised rodent lungs for functional hyperpolarized xenon-129 MRI.

Ex vivo rodent lung models are explored for physiological measurements of respiratory function with hyperpolarized (hp) 129Xe MRI. It is shown that excised lung models allow for simplification of the technical challenges involved and provide valuable physiological insights that are not feasible using in vivo MRI protocols. A custom designed breathing apparatus enables MR images of gas distribution on increasing ventilation volumes of actively inhaled hp 129Xe. Straightforward hp 129Xe MRI protocols provide residual lung volume (RV) data and permit for spatially resolved tracking of small hp 129Xe probe volumes during the inhalation cycle. Hp 129Xe MRI of lung function in the excised organ demonstrates the persistence of post mortem airway responsiveness to intravenous methacholine challenges. The presented methodology enables physiology of lung function in health and disease without additional regulatory approval requirements and reduces the technical and logistical challenges with hp gas MRI experiments. The post mortem lung functional data can augment histological measurements and should be of interest for drug development studies.

Single-Molecule Measurements of Transient Biomolecular Complexes through Microfluidic Dilution

Single-molecule confocal microscopy experiments require concentrations which are low enough to guarantee that, on average, less than one single molecule resides in the probe volume at any given time. Such concentrations are, however, significantly lower than the dissociation constants of many biological complexes which can therefore dissociate under single-molecule conditions. To address the challenge of observing weakly bound complexes in single-molecule experiments in solution, we have designed a microfluidic device that rapidly dilutes samples by up to one hundred thousand times, allowing the observation of unstable complexes before they dissociate. The device can interface with standard biochemistry laboratory experiments and generates a spatially uniform dilution that is stable over time allowing the quantification of the relative concentrations of different molecular species.

Effects of droplet collision phenomena on the development of pressure swirl sprays

In this work, the sprays generated by a pressure swirl atomizer were examined for different liquid injection pressures and particularly, the effects of the droplet collision phenomena on the axial evolution of the droplet size distribution were carefully studied. Sizes and droplet velocities were measured by means a phase Doppler particle analyzer and number concentrations and liquid volume fluxes for different droplet classes, were evaluated using a full data post-processing based on the droplet transit time inside the probe volume. The collision rates between droplet classes were calculated and some collision outcomes as coalescence and separation were investigated.In all the sprays studied, the highest collision rates were obtained in the region where both high number concentration and elevated relative velocity between droplets were measured. A progressive increase of the droplet mean diameter was produced along the sprays due to the coalescing collisions. As injection pressure increased, higher droplet collision rates and higher inertia collisions were found. The separation with formation of satellite droplets was a more frequent collision outcome. In addition, bigger axial mean free paths were calculated and hence, a more moderated axial increase of the droplet mean diameter was obtained.

뇌 삽입형 신경 접속 마이크로 시스템의 구현상 이슈

In this paper, we investigate several important issues on the implementation of a totally implantable microsystem for brain-machine interface that has been attracting a lot of attention recently. So far most of the scientific research has been focused on the high performance, low power electronics or systems such as neural signal amplifiers and wireless signal transmitters, but the real application of the implantable microsystem is affected significantly by a number of factors, ranging from design of the encapsulation structure to physiological and anatomical characteristics of the brain. In this work, we discuss on the thermal effect of the system, the detecting volume of the neural probes, wireless data transmission and power delivery, and physiological and anatomical factors that are critically important for the actual implementation of a totally brain implantable neural interface microsystem.

Parallax correction for precise near-wall flow investigations using particle imaging

For the basic understanding of turbulence generation in wall-bounded flows, precise measurements of the mean velocity profile and the mean velocity fluctuations very close to the wall are essential. Therefore, three techniques are established for high-resolution velocity profile measurements close to solid surfaces: (1) the nanoprobe sensor developed at Princeton University, which is a miniaturization of a classical hot-wire probe [Exp. Fluids 51, 1521 (2011)]; (2) the laser Doppler velocimetry (LDV) profile sensor, which allows measurement of the location of the particles inside the probe volume using a superposition of two fringe systems [Exp. Fluids 40, 473 (2006)]; and (3) the combination of particle image velocimetry and tracking techniques (PIV/PTV), which identify the location and velocity of submicrometer particles within the flow with digital imaging techniques [Exp. Fluids 52, 1641 (2006)]. The last technique is usually considered less accurate and precise than the other two. However, in addition to the measurement precision, the effect of the probe size, the position error, and errors due to vibrations of the model, test facility, or measurement equipment have to be considered. Taking these into account, the overall accuracy of the PTV technique can be superior, as all these effects can be compensated for. However, for very accurate PTV measurements close to walls, it is necessary to compensate the perspective error, which occurs for particles not located on the optical axis. In this paper, we outline a detailed analysis for this bias error and procedures for its compensation. To demonstrate the capability of the approach, we measured a turbulent boundary layer at Re(δ)=0.4×10(6) and applied the proposed methods.

Direct deconvolution approach for depth profiling of element concentrations in multi-layered materials by confocal micro-beam X-ray fluorescence spectrometry

A new approach for the determination of element concentration profiles in stratified materials by confocal X-ray fluorescence spectrometry was elaborated. The method was based on a direct deconvolution of the measured depth-dependent X-ray fluorescence intensity signal with the established response function of the spectrometer. Since the approach neglects the absorption of primary and secondary radiation within the probing volume, it is applicable only to low absorbing samples and small probing volumes. In the proposed approach the deconvolution is performed separately for all detectable elements and it is followed by the correction of absorption effects. The proposed approach was validated by using stratified standard samples. The determined elemental profiles were compared with the results obtained by using existing analytical approaches.

Designing a unique reporter based microarray sensor platform for monitoring cell signalling.

PurposeBiological processes in mammalian cells are driven by gene expression that is in turn regulated by transcription factors (TFs). The latter are controlled by a series of complex network of biochemical pathways that represent the core for cell signalling. There has been little success in monitoring cell signalling using traditional methods such as proteomics. In this report we demonstrate the possibility of deconvoluting such complexity using a multiplexed library of plasmids carrying a TF binding site upstream of a unique reporter sequence (UR). A microarray sensor platform was then used to monitor dynamic changes in cells by measuring UR expression levels.MethodsHEK293 cells, treated with various drugs and inducers, were transfected with the multiplexed plasmid library. mRNA was then purified and reverse transcribed to produce first strand cDNA. The latter was then amplified by PCR using a universal fluorescently labelled primer. Purified PCR amplicons were then hybridized with antisense oligonucleotide captures at 53°C. Epoxy slides were then washed and quantified using the ScanArray Express Scanner (Perkin Elmer).ResultsThe microarray platform was optimized to detect down to 1 attomol with a maximal degree of specificity and a minimal probe volume of 2μl. This platform was able to detect changes in the TF activity following treatment of cells with dexamethazone, cadmium, forskolin, TPA, cAMP analogues, cGMP analogues and PDEIs. The data was consistent with qPCR and western blot analysis.ConclusionThe microarray platform was shown to be robust, sensitive and reproducible in monitoring dynamic changes in mammalian cells. The system can be easily tailored to include transcription factors of interest to fit with the required purposes.

Absolute density measurement of SD radicals in a supersonic jet at the quantum-noise-limit

The absolute density of SD radicals in a supersonic jet has been measured down to (1.1 ± 0.1) × 10(5) cm(-3) in a modestly specified apparatus that uses a cross-correlated combination of cavity ring-down and laser-induced fluorescence detection. Such a density corresponds to 215 ± 21 molecules in the probe volume at any given time. The minimum detectable absorption coefficient was quantum-noise-limited and measured to be (7.9 ± 0.6) × 10(-11) cm(-1), in 200 s of acquisition time, corresponding to a noise-equivalent absorption sensitivity for the apparatus of (1.6 ± 0.1) × 10(-9) cm(-1) Hz(-1/2).

扩展光束型激光多普勒速度测量系统

To acquire the instantaneous velocity outside the chamber of a high-speed bullet and its velocity distribution at different positions,this paper proposed a velocity measurement system with expanded beams based on the laser Doppler effect.The system expanded the exiting laser beam for two times and then made the two coherent beams intersect in the space to form a new probe volume with two dimensional broadening lengths.The system efficiently overcame the object deviation from the measurement region caused by the smaller probe volume in the traditional Laser Doppler Velocimiter(LDV).Therefore,it could measure the velocity of high-speed bullet that traditional LDV could not implement because of the trajectory deviation.Moreover,the system could also monitor the velocity distribution of the high-speed bullet at different positions in the trajectory by a parallel mode.Experiments for expanding different lasers were performed in different illuminating lights,and the Doppler signals were obtained from the photo-detector finally.The analysis results show that the average error of the measured velocities at 10-25 m/s can reach 1%-2%,which indicate that the proposed method is effective and feasible.

Helium Ion Microscopy of Uncoated Pine Leaves

A recently introduced helium ion microscopy (HIM) was employed to observe uncoated pine leaf specimens. Adult leaves were collected from the seedlings of Pinus densiflora and P. rigida, air-dried at room temperature, and observed by HIM without metal coating. Ovoid or round stomata and distinct Florin rings could be discerned. The epicuticular waxes were present in the epistomatal chambers and Florin rings of stomata on the leaf surface. The epicuticular waxes were mostly straight, cylindrical, and ca. 1 <TEX>${\mu}m$</TEX> in length. The epistomatal chambers of P. rigida were filled with the epicuticular waxes, whereas those of P. densiflora were not filled with the epicuticular waxes. Based on their micromorphology, the epicuticular wax structures of the pine species were identified as tubules. These results suggest that the HIM could be used for the investigation of the plant stomata and epicuticular waxes of uncoated plant leaves. Due to the smaller ion probe and interaction volume, the HIM has advantages over conventional field emission scanning electron microscopy in terms of image resolution and charge neutralization.