bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron transport parameters in CO2: a comparison of two experimental systems and measured data
Authors: Vass Máté , Egüz Eda , Chachereau Alise , Hartmann Péter , Korolov Ihor , Hösl Andreas , Bošnjaković Danko , Dujko Saša , Donkó Zoltán , Franck Christian M 
Published: September 2020

Abstract
Two experimental apparatuses used to obtain electron transport coefficients in gases are compared based on measurements in CO2 over a wide range of E/N-values. The operation principles of the two experimental systems as well as their data acquisition methods are different. One operates under the time of flight (TOF) principle, where the transport coefficients are obtained by fitting the theoretical form of the electron density of a swarm in an unbounded region, n(x, t), to the measured current at different values of the drift length, I(L, t). The other experimental apparatus operates in the Pulsed Townsend (PT) mode, where the electron transport coefficients are obtained by fitting the spatial integral of n(x, t) over the drift region to the measured, time-dependent current signal, I(t). In both apparatuses, the measured E/N range was extended as much as possible to allow a large overlap for the comparison of the results. The bulk drift velocity, W, obtained by the two systems agrees well (within a few %) over a wide range of E/N values (100 Td ≤ E/N ≤ 1000 Td). The agreement between the data sets for the longitudinal component of the bulk diffusion tensor,

D

L

, is less satisfactory, the TOF data show systematically higher values (by 10–50% depending on E/N) than the PT measurements. Significant differences are also found below 100 Td in case of the effective ionisation frequency,

ν

e
f
f

, and the (steady state) Townsend ionisation coefficient,

α

e
f
f

, where the TOF apparatus is unable to give accurate results. Our comparison justifies the correctness of the measured data over the range of agreement and also indicates the interval in E/N where the data obtained by each of the experimental systems can be taken to be reliable. The limits of the operating regimes of the two setups, stemming from the hardware and from the physical limits, are discussed.
Se diffusion in CdTe thin films for photovoltaics
Authors: Colegrove Eric , Zheng Xin , Ablekim Tursun , Duenow Joel N , Perkins Craig L , Moutinho Helio R , Metzger Wyatt K 
Published: September 2020

Abstract
Manipulating CdSeTe bandgrading to enhance photocurrent and carrier lifetime is an essential part of high-performance CdTe photovoltaics (PVs). In this work, we examine Se diffusion kinetics in single-crystal and polycrystalline CdTe during deposition, thermal annealing, and CdCl2 treatments. Se distributions are determined by dynamic secondary-ion-mass spectroscopy and Auger electron spectroscopy depth profiling and coupled with electron backscatter diffraction images of the crystalline structure. Effective bulk and grain boundary diffusion coefficients are determined by analytical models and discussed in the context of processing and film morphology. Se is found to diffuse in CdTe at much higher rates during CdCl2 treatments than with thermal processing alone. GB diffusion also occurs at a significantly faster rate than bulk diffusion. As a result of these two effects, the near interface bulk and GB Se diffusion during CdCl2 treatments dominates the bandgrading profiles in CdTe PVs.
Thermal magnetic fluctuations of a ferroelectric quantum critical point
Authors: Khaetskii Alexander , Juričič Vladimir , Balatsky Alexander V 
Published: September 2020

Abstract
Entanglement of two different quantum orders is of an interest of the modern condensed matter physics. One of the examples is the dynamical multiferroicity, where fluctuations of electric dipoles lead to magnetization. We investigate this effect at finite temperature and demonstrate an elevated magnetic response of a ferroelectric near the ferroelectric quantum critical point (FE QCP). We calculate the magnetic susceptibility of a bulk sample on the paraelectric side of the FE QCP at finite temperature and find enhanced magnetic susceptibility near the FE QCP. We propose quantum paraelectric strontium titanate as a candidate material to search for dynamic multiferroicity. We estimate the magnitude of the magnetic susceptibility for this material and find that it is detectable experimentally.
First principles investigation of electron correlation and Lifshitz transition within iron polynitrides
Authors: Feng Qingguo 
Published: September 2020

Abstract
Metal poly-nitrogen compounds are gaining great interests as potential high energy density materials. Several iron polynitrides have been recently synthesized and investigated under high pressure (2018 Nature Communications
9 2756). In this work the electron correlations within these iron poly-nitrogen compounds were self-consistently determined, benchmarked with those obtained from linear response approach. Along with the increase of the concentration of nitrogen, the Coulomb interaction strengths show a monotonic decrease, where FeN and FeN2 are antiferromagnetic and the others are ferromagnetic. Then the electron correlation is studied along with the pressure, where the electrons are more delocalized as pressure becomes higher. One electronic topological transition was found for FeN2, owing to a breaking of symmetry of spin and a transition of magnetism induced by a structural change. The band structure, densities of states, Fermi surface and absorption spectra were calculated and discussed.
New image reconstruction algorithm for CCERT: LBP + Gaussian mixture model (GMM) clustering
Authors: Wang Yuxin , He Xuekai , Jiang Yandan , Wang Baoliang , Ji Haifeng , Huang Zhiyao 
Published: September 2020

Abstract
This work focuses on the study of the image reconstruction algorithm of capacitively coupled electrical resistance tomography (CCERT). With the combination of a linear back projection (LBP) algorithm and an unsupervised Gaussian mixture model (GMM) algorithm, a new image reconstruction algorithm for CCERT is proposed. The LBP algorithm is used to implement the initial image reconstruction. The GMM algorithm is adopted to acquire the gray level threshold which will be used for the establishment of the gray level threshold filter. The final reconstructed image can be obtained with the thresholding operation. With a developed 12-electrode CCERT prototype system, the new image reconstruction algorithm is tested in image reconstruction experiments. The experimental results show that the proposed new image reconstruction algorithm is effective. The image reconstruction results are satisfactory. Compared with the conventional image reconstruction algorithms, the new image reconstruction algorithm (LBP + GMM) can obtain better reconstructed images with smaller relative image errors. It can obtain the reconstructed images with fewer empirical preset parameters and less manual intervention. In addition, with the introduction of the GMM algorithm, a relatively more suitable and reasonable gray level threshold can be obtained because the GMM algorithm implements the clustering process by utilizing both mean and variance information on the gray level distribution. Thus, better image reconstruction results can be obtained.
Monitoring corrosion-induced thickness loss of stainless steel plates using the electromechanical impedance technique
Authors: Liu Yang , Feng Xin 
Published: September 2020

Abstract
Stainless steel plates are widely used in steel structures. Corrosion damage of a stainless steel plate can induce the thickness and mass loss of the stainless steel plate. The corrosion-induced thickness loss (CITL) is one of the main reasons for the degradation of the stiffness and bearing capacity of the stainless steel plate, which endangers the safety of the structure and causes economic losses. Therefore, effective monitoring of the CITL of the stainless steel plate can help to ensure the safety of steel structures. In this study, a novel monitoring method for the CITL of the stainless steel plate based on the electromechanical impedance (EMI) technique is presented. The effective mechanical admittance (EMA) of a simply supported thin stainless steel plate under the excitation of a single surface-bonded piezoelectric transducer is derived theoretically; the resonance frequency shift (

Δ
f

) of the bending vibration mode in the admittance signature is extracted as the CITL-sensitive feature to identify the CITL of the stainless steel plate. The quantitative relationship between

Δ
f

and CITL, based on the EMA, is established theoretically for monitoring the CITL of the stainless steel plate. The effectiveness of the proposed method is verified by experiments. The experimental results demonstrate that the proposed method can sensitively identify, accurately quantify and predict the CITL of the stainless steel plate, and has excellent stability and reliability. This method can not only overcome the limitation of the existing statistics-based EMI methods that cannot quantify the CITL, but also compensate for the weakness of commonly-used non-destructive testing methods that cannot quantitatively predict CITL in an on-line monitoring manner. The proposed method provides an effective monitoring and tracking tool for the CITL of the stainless steel plate.
Magnetic mesoporous silica nanospheres with dual probe & release fluorescent functionality
Authors: Tancredi Pablo , Rivas-Rojas Patricia C , Veiga Lionel S , Garate Octavio , Socolovsky Leandro M , Muraca Diego , Ybarra Gabriel 
Published: September 2020

Abstract
The combination of different nanomaterials through step-by-step synthesis procedures has turned into a promising alternative to fabricate high-quality nanosystems in order to satisfy the increasingly demanding requirements of the biomedical field. In this work, we report a detailed study on the synthesis and characterization of a complex nanosystem composed of nanoparticles with a single magnetic nanoparticle core and a shell of dense and mesoporous silica arranged in layers. The procedure designed to fabricate these systems lead us to the formation of a dispersion of non-agglomerated spherical nanoparticles of nearly 100 nm. The structural characterization performed over the final samples confirmed both the prevalence of single-core systems and the presence of the mesoporous silica shell in the outer layer. The performance of the nanosystem in a specific technological application was tested by sequentially loading two different fluorescents molecules by covalent and non-covalent bonding strategies. Due to the distinct loading strategies, the resulting nanosystem presented a magnetically-assisted probe & release functionality as analyzed in a magnetophoretic experiment.
Study of adhesion and migration dynamics in ubiquitin E3A ligase (UBE3A)-silenced SYSH5Y neuroblastoma cells by micro-structured surfaces
Authors: Mezzena R , Masciullo C , Antonini S , Cremisi F , Scheffner M , Cecchini M , Tonazzini I 
Published: September 2020

Abstract
During neuronal development, neuronal cells read extracellular stimuli from the micro/nano-environment within which they exist, retrieving essential directionality and wiring information. Here, focal adhesions (FAs-protein clusters anchoring integrins to cytoskeleton) act as sensors, by integrating signals from both the extracellular matrix environment and chemotactic factors, contributing to the final neuronal pathfinding and migration. In the processes that orchestrate neuronal development, the important function of ubiquitin E3A ligase (UBE3A) is emerging. UBE3A has crucial functions in the brain and changes in its expression levels lead to neurodevelopmental disorders: the lack of UBE3A leads to Angelman syndrome (AS, OMIN 105830), while its increase causes autisms (Dup15q-autism). By using nano/micro-structured anisotropic substrates we previously showed that UBE3A-deficient neurons have deficits in contact guidance (Tonazzini et al, Mol Autism 2019).
Here, we investigate the adhesion and migration dynamics of UBE3A-silenced SH-SY5Y neuroblastoma cells in vitro by exploiting nano/micro-grooved substrates. We analyze the molecular processes regulating the development of FAs by transfection with EGFP-vector encoding for paxillin, a protein of FA clusters, and by live-cell total-internal-reflection-fluorescence microscopy. We show that UBE3A-silenced SH-SY5Y cells have impaired FA morphological development and pathway activation, which lead to a delayed adhesion and also explain the defective contact guidance in response to directional topographical stimuli. However, UBE3A-silenced SH-SY5Y cells show an overall normal migration behavior, in terms of speed and ability to follow the GRs directional stimulus. Only the collective cell migration upon cell gaps was slightly delayed for UBE3Ash SHs. Overall, the deficits of UBE3Ash SHS-SY5Y cells in FA maturation/sensing and in collective migration may have patho-physiological implications, in AS condition, considering the much more complex stimuli that neurons find in vivo during the neurodevelopment.
Electron beam evaporated Au islands as a nanoscale etch mask on few-layer MoS2 and fabrication of top-edge hybrid contacts for field-effect transistors
Authors: Walter Timothy N , Oliver Nailah , Mohney Suzanne E 
Published: September 2020

Abstract
Metal contacts to two-dimensional layered semiconductors are crucial to the performance of field-effect transistors (FETs) and other applications of layered materials in nanoelectronics and beyond. In this work, the wetting behavior of very thin Au films on exfoliated MoS2 flakes was studied and evaluated as a nanoscale, self-assembled dry etch mask. Etching nanoscale pits into MoS2 flakes prior to metallization from the top of the flake forms edge sites that contribute some fraction of edge contacts in addition to top contacts for additional carrier injection and lower contact resistance. The morphology and thickness of Au islands and MoS2 were studied with scanning electron microscopy and atomic force microscopy before and after etching with low-power plasmas. A Cl2 plasma etch of 10 s with a Au island mask of 6 nm (nominal) showed the best resulting morphology among the plasma conditions studied. Back-gated MoS2-based FETs on SiO2/p
+-Si with Ti/Au contacts were fabricated using a Cl2 etch of only the contact regions, and they yielded devices with ON currents of 100s µA/µm, ON/OFF ratios ⩾106, and contact resistance <10 kΩ µm. The best set of devices had a very low contact resistance of ∼1 kΩ µm with almost no dependence of contact resistance on gating. Using nanoscale etch masks made from metal islands could be highly customizable and shows promise for engineering FETs with low contact resistance.
Investigating chirping steel balls: a novel set-up
Authors: Chua Xian Wei 
Published: September 2020

Abstract
The International Young Physicists’ Tournament (IYPT) is a worldwide, annual competition for high school students. This paper is adapted from the author’s investigation into problem 4, Ball Sound, of the 27th IYPT. A novel set-up is proposed to investigate the unusual ‘chirping’ sound produced when two hard steel balls, or similar, are brought gently into contact with each other. It is shown that the decreasing time interval between rapid successive ball collisions, and not surface acceleration, is responsible for the chirping phenomenon. The proposed set-up simulates the collision of steel balls using our hands, and provides effective physical insights into the mechanism of chirp production.
Noise modeling and variance stabilization of a computed radiography (CR) mammography system subject to fixed-pattern noise
Authors: Borges Lucas R , Brochi Marco A C , Xu Zhongwei , Foi Alessandro , Vieira Marcelo A C , Azevedo-Marques Paulo M 
Published: September 2020

Abstract
In this work we model the noise properties of a computed radiography (CR) mammography system by adding an extra degree of freedom to a well-established noise model, and derive a variance-stabilizing transform (VST) to convert the signal-dependent noise into approximately signal-independent. The proposed model relies on a quadratic variance function, which considers fixed-pattern (structural), quantum and electronic noise. It also accounts for the spatial-dependency of the noise by assuming a space-variant quantum coefficient. The proposed noise model was compared against two alternative models commonly found in the literature. The first alternative model ignores the spatial-variability of the quantum noise, and the second model assumes negligible structural noise. We also derive a VST to convert noisy observations contaminated by the proposed noise model into observations with approximately Gaussian noise and constant variance equals to one. Finally, we estimated a look-up table that can be used as an inverse transform in denoising applications. A phantom study was conducted to validate the noise model, VST and inverse VST. The results show that the space-variant signal-dependent quadratic noise model is appropriate to describe noise in this CR mammography system (errors< 2.0% in terms of signal-to-noise ratio). The two alternative noise models were outperformed by the proposed model (errors as high as 14.7% and 9.4%). The designed VST was able to stabilize the noise so that it has variance approximately equal to one (errors< 4.1%), while the two alternative models achieved errors as high as 26.9% and 18.0%, respectively. Finally, the proposed inverse transform was capable of returning the signal to the original signal range with virtually no bias.
Probing spatiotemporal fractionation on the preclinical level
Authors: Telarovic Irma , Krayenbuehl Jerome , Grgic Ivo , Tschanz Fabienne , Guckenberger Matthias , Pruschy Martin , Unkelbach Jan 
Published: September 2020

Abstract
In contrast to conventional radiotherapy, spatiotemporal fractionation (STF) delivers a distinct dose distribution in each fraction. The aim is to increase the therapeutic window by simultaneously achieving partial hypofractionation in the tumour along with near uniform fractionation in normal tissues. STF has been studied in silico under the assumption that different parts of the tumour can be treated in different fractions. Here, we develop an experimental setup for testing this key assumption on the preclinical level using high-precision partial tumour irradiation in an experimental animal model. We further report on an initial proof-of-concept experiment. We consider a reductionist model of STF in which the tumour is divided in half and treated with two complementary partial irradiations separated by 24 h. Precise irradiation of both tumour halves is facilitated by the image-guided small animal radiation research platform X-RAD SmART. To assess the response of tumours to partial irradiations, tumour growth experiments are conducted using mice carrying syngeneic subcutaneous tumours derived from MC38 colorectal adenocarcinoma cells. Tumour volumes were determined daily by calliper measurements and validated by CT-volumetry. We compared the growth of conventionally treated tumours, where the whole tumour was treated in one fraction, to the reductionist model of STF. We observed no difference in growth between the two groups. Instead, a reduction in the irradiated volume (where only one half of the tumour was irradiated) resulted in an intermediate response between full irradiation and unirradiated control. The results obtained by CT-volumetry supported the findings of the calliper-derived measurements. An experimental setup for precise partial tumour irradiation in small animals was developed, which is suited to test the assumption of STF that complementary parts of the tumour can be treated in different fractions on the preclinical level. An initial experiment supports this assumption, however, further experiments with longer follow-up and varying fractionation schemes are needed to provide additional support for STF.
EXIRAD-HE: multi-pinhole high-resolution ex vivo imaging of high-energy isotopes
Authors: Nguyen Minh Phuong , Goorden Marlies C , Beekman Freek J 
Published: September 2020

Abstract
We recently developed a dedicated focusing multi-pinhole collimator for a stationary SPECT system that offers down to 120 µm (or 1.7 nL) spatial resolution SPECT images of cryo-cooled tissue samples (EXIRAD-3D). This collimator is suitable for imaging isotopes that are often used in small animal and diagnostic SPECT such as 125I (27 keV), 201Tl (71 keV), 99mTc (140 keV), and 111In (171 and 245 keV). The goal of the present work is to develop high-resolution pinhole imaging of tissue samples containing isotopes with high-energy photon emissions, for example, therapeutic alpha and beta emitters that co-emit high energy gammas (e.g. 213Bi (440 keV) and 131I (364 keV)) or 511 keV annihilation photons from PET isotopes. To this end, we optimise and evaluate a new high energy small-bore multi-pinhole collimator through simulations. The collimator-geometry was first optimised by simulating a Derenzo phantom scan with a biologically realistic activity concentration of 18F at two system sensitivities (0.30% and 0.60%) by varying pinhole placements. Subsequently, the wall thickness was selected based on reconstructions of a Derenzo phantom and a uniform phantom. The obtained collimators were then evaluated for 131I (364 keV), 213Bi (440 keV), 64Cu (511 keV), and 124I (511 + 603 keV) with biologically realistic activity concentrations, and also for some high activity concentrations of 18F, using digital resolution, mouse knee joint, and xenograft phantoms. Our results show that placing pinhole centres at a distance of 8 mm from the collimator inner wall yields good image quality, while a wall thickness of 43 mm resulted in sufficient shielding. The collimators offer resolutions down to 0.35 mm, 0.6 mm, 0.5 mm, 0.6 mm, and 0.5 mm when imaging 131I, 213Bi, 18F, 64Cu, and 124I, respectively, contained in tissue samples at biologically achievable activity concentrations.
Strain and stress effects on single crystal-supported titania and related nanostructures
Authors: Pang Chi Lun 
Published: September 2020

Abstract
The properties of materials can be altered by introducing strain. For instance, the critical temperature of superconductors has been raised as has the Curie temperature of ferroelectric materials. As TiO2 is the most studied single crystal metal oxide, it is highly desirable to understand how strain might be used to tune its properties. Theoretical calculations indicate that the band gap of anatase TiO2 may be lowered, which would remove one of the roadblocks to its wider use as a photocatalyst. Surface defects on rutile TiO2 are responsible for a large part of its reactivity and the nature of these may also be affected by strain according to calculations. In this review, the introduction of strain and its effect on reactivity will be examined. The strain in the most part arises from lattice mismatch in the growth of TiOx films on various substrates although cases where TiO2 is the substrate are also included as is the implantation of Ar clusters in the subsurface of TiO2.