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Live-cell super-resolution microscopy reveals a primary role for diffusion in polyglutamine-driven aggresome assembly
摘要： The mechanisms leading to self-assembly of misfolded proteins into amyloid aggregates have been studied extensively in the test tube under well-controlled conditions. However, to what extent these processes are representative of those in the cellular environment remains unclear. Using super-resolution imaging of live cells, we show here that an amyloidogenic polyglutamine-containing protein first forms small, amorphous aggregate clusters in the cytosol, chiefly by diffusion. Dynamic interactions among these clusters limited their elongation and led to structures with a branched morphology, differing from the predominantly linear fibrils observed in vitro. Some of these clusters then assembled via active transport at the microtubule-organizing center and thereby initiated the formation of perinuclear aggresomes. Although it is widely believed that aggresome formation is entirely governed by active transport along microtubules, here we demonstrate, using a combined approach of advanced imaging and mathematical modeling, that diffusion is the principal mechanism driving aggresome expansion. We found that increasing surface area of the expanding aggresome increases the rate of accretion due to diffusion of cytosolic aggregates and that this pathway soon dominates aggresome assembly. Our findings lead to a different view of aggresome formation than that proposed previously. We also show that aggresomes mature over time, becoming more compacted as the structure grows. The presence of large perinuclear aggregates profoundly affects the behavior and health of the cell, and our super-resolution imaging results indicate that aggresome formation and development are governed by highly dynamic processes that could be important for the design of potential therapeutic strategies.
关键词： molecular modelling,protein aggregation,molecular imaging,passive transport,amyloid protein,aggresome formation,transport,live cell SIM,protein misfolding,molecular dynamics
更新于2025-09-23 15:21:21
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New approaches on laser micro welding of copper by using a laser beam source with a wavelength of 450 nm
摘要： Laser micro welding is specified with welding geometries below 1 mm and is used with increasing demand for contacting electronic components such as battery and fuel cells. Fiber lasers with a wavelength in the near infrared range (IR, λ ≈ 1 μm) have established themselves for this purpose. The laser welding process allows processing of parts in the micron range but reduces the surface quality of the processed parts at the same time. Furthermore, weld defects can occur due to process instabilities caused by the low absorptivity (<5%) of copper for infrared radiation. Therefore, alternative laser beam sources and processes have to be established, to avoid these negative effects on the weld seam quality. Laser beam sources in the visible wavelength range (VIS) prove to be an alternative due to an increased absorption of the laser energy in copper-based alloys. This paper presents the observation of laser micro welding of Cu-ETP and CuSn6 specimen with a thickness between 150 μm and 1 mm. The diode laser is specified by a wavelength of 450 nm and a nominal output power of 150 W. The surface roughness of the weld seam and the overall weld seam geometry for heat conduction welding are investigated. The laser energy absorption is measured using two integrating spheres to compare the results quantitatively to measurements conducted with laser sources of 1070 nm and 515 nm. For detailed observation high speed imaging is used to observe the melt pool dynamics. Simulations are conducted, to optimize the dimensioning of optics and laser beam source. Finally, the possible use of the novel laser beam source for various technical joining applications is discussed and evaluated and the influence of the use of protective gas is observed.
关键词： heat conduction welding,scanner system,laser micro welding,copper,modelling,450 nm
更新于2025-09-23 15:21:01
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Improving project communication in the architecture, engineering and construction industry: Coupling virtual reality and laser scanning
摘要： In recent years, the demand for accurate, clear and easy-understandable information has been steadily rising within the Architecture, Engineering and Construction (AEC) industry’s stakeholders. Despite this, a sizeable portion of this industry still considers the traditional approach to Construction Engineering, disregarding major innovations and technologic advances. This not only poses a great obstacle to proper communication between project-related entities but also presents a significant challenge for retrofitting projects. This article proposes a workflow for the improvement of communication in construction projects, in particular between professionals who lack specific BIM skills. Thus, by coupling laser scanning and Virtual Reality (VR), within a Building Information Modelling (BIM) work environment, this workflow comprises the entire process from on-site geometric data acquisition, through data treatment and analysis, culminating with the point-cloud importation into a game engine and the development of navigation and interaction tools within the VR environment. The framework is validated through its application to a proof of concept, from which conclusions regarding the workflow success, limitations, optimization, among other topics are discussed.
关键词： Project communication,Building retrofitting,Laser scanning surveying,Building Information Modelling,Virtual Reality
更新于2025-09-23 15:21:01
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Selection of optimal wavelengths for optical soiling modelling and detection in photovoltaic modules
摘要： Soiling impacts the photovoltaic (PV) module performance by reducing the amount of light reaching the photovoltaic cells and by changing their external spectral response. Currently, the soiling monitoring market is moving toward optical sensors that measure transmittance or reflectance, rather than directly measuring the impact of soiling on the performance of photovoltaic modules. These sensors, which use a single optical measurement, are not able to correct the soiling losses that depend on the solar irradiance spectra and on the spectral response of the monitored PV material. This work investigates methods that can improve the optical detection of soiling by extracting the full soiling spectrum profiles using only two or three monochromatic measurements. Spectral transmittance data, measured with a spectrophotometer and collected during a 46-week experimental soiling study carried out in Ja?en, Spain, was analysed in this work. The use of a spectral profile for the hemispherical transmittance of soiled PV glass is found to significantly improve the soiling detection, returning the lowest errors independently of the PV materials and irradiance conditions. In addition, this work shows that it is also possible to select the measurement wavelengths to minimize the soiling loss detection error depending on the monitored PV semiconductor material (silicon, CdTe, a-Si, CIGS and a representative perovskite). The approaches discussed in this work are also found to be more robust to potential measurement errors compared to single wavelength measurement techniques.
关键词： Soiling,Dust,Optical modelling,Photovoltaic,Spectral losses,Reliability
更新于2025-09-23 15:21:01
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Simulation of Optical and Electrical Losses of PV Modules in Moderate and Desert Conditions
摘要： Measurements of the PV modules are based on standard test conditions. However, PV modules have significant difference in performance based on the locations, environmental conditions and mounting situation. One of the environmental factors which influence the performance of the PV module is the spectrum of incident light on the PV module. In this paper, we compare the optical reflection losses, thermal losses as well as electricity production of modules under moderate (AM1.5) and desert-like spectrums (AM1.0). The results show quantitatively that thermalization has the highest loss portion with an average of 29.5% of the total incoming power density for both spectrums. The highest relative change is for absorption of light in polymer encapsulant especially between 280-400 nm with 24.3% and total resistive losses (in cell and interconnection) with 21.3% extra losses from desert to moderate conditions. Finally, we show that similar modules in desert climate produce 5% extra power gain while it suffers from 7.2% extra heat and 5% extra reflections.
关键词： Photovoltaic cells,Si PV Modelling,Metrology and Characterization,PV,Crystalline Silicon PV
更新于2025-09-23 15:21:01
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[Energy, Environment, and Sustainability] Advances in Solar Energy Research || Reduced Order Heat Exchanger Models for Low-to-Medium Temperature Range Solar Thermal Applications
摘要： Pivotal heat transfer components of solar thermal systems may involve single phase flow of the working fluid in some unit (e.g. single phase solar collector), whereas, two phase flow of the working fluid occurs in the other units (e.g. two-phase solar collector coupled directly to the turbine, boilers and evaporators). Modelling of these systems are important to understand the heat transfer behavior, as well as, to develop the system level control among many other attributes. A detailed analysis of single phase and two phase systems is possible using mathematical models to characterize the fluid flow and heat transfer. Detailed description of the fluid flow and heat transfer become computationally very expensive with such models, and also a very high level of precision may not be required in large time (*few hours) simulations of the systems, as well as, in controlling the entire solar thermal power plant. Hence there is a need to develop computationally fast, low order dynamic models. Among many other modelling approaches, a particular class of heat exchanger model, namely the moving boundary lumped-parameter model, has emerged as an efficient and effective tool for simulating dynamic characteristics of the two-phase solar collectors and the evaporators, pertinent to organic Rankine cycle (ORC) systems. These models are efficient in locating the continuously moving working fluid phase change boundary to the without requiring any sophisticated, well-trained formulation pertinent starting solutions. Even a simplified, reduced order quasi-steady state model is capable of demonstrating moving boundary characteristics in a narrow evaporator tube that is employed to carry organic refrigerant (working fluid) into the two-phase thermal applications in the medium temperature solar ORC heat exchanger (*200 °C). The model is capable of predicting the variation in working fluid mass transfer fluid (usually a flow rates with time-varying temperature of the heat
关键词： Reduced order modelling,Solar thermal system,Moving boundary model
更新于2025-09-23 15:21:01
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A new static method of calibration for low-cost laser triangulation systems
摘要： As a non-contact high-ef?ciency method, laser triangulation has long been studied by many scholars. Building such a system usually requires calibration where system parameters are found or amended to achieve the targeted precision. Traditional calibration methods require using either precise movement or high precision gauge object that are accompanied with extra manufacturing cost and auxiliary equipment/devices and hence increase the overall cost as well as prevent widespread applications, for instance, due to required environment conditions to be ful?lled. A new static method was, therefore, proposed to calibrate a system without need of a motion or a high precision gauge object to be deployed. The method relies on preparation of the data on a scalar compound target with a geometric estimator as quality indicator. Based on this method, three versions of a low-cost prototype were built, which achieved sub-millimeter precision. Although the precision is suf?cient for a measurement often used manufacturing large panels, higher precision is achievable with additional work which is to be undertaken in the future. The proposed method makes tradeoff between precision and cost. This was followed by testing on the measurement of a small panel part as application-case study. The proven feasibility of the method proposed suggested potential of developing low-cost, inline industrial system (large or small) for inspecting sheet parts during manufacturing, especially panel component manufacturing, including that from metal sheets and composite materials.
关键词： Calibration,Inspection,Panel manufacturing,Measurement,Modelling,Laser triangulation
更新于2025-09-23 15:21:01
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Understanding partial shading effects in shingled PV modules
摘要： Shingled solar modules are one of several technologies currently being considered to obtain higher solar module efficiencies. Using equivalent circuit modelling this paper investigates the robustness of shingled modules to partial shading with respect to the power produced and the power dissipated in shaded shingles. The modeling results are experimentally verified. We find that power losses in shingled modules can be larger than in conventional modules for similar shading conditions. The risk of significant local heating resulting from partial shading, potentially leading to catastrophic module failure can also be higher in shingled modules due to the substantially higher reverse biases experienced by shaded shingles. Both risks can effectively be mitigated by operating each shingled module at its own maximum power point, for instance by using module level power electronics on each module or by incorporating a sufficient number of bypass diodes into the module design.
关键词： Partial shading,High efficiency modules,Hot spots,Modelling,Shingled modules
更新于2025-09-23 15:21:01
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Temperature dependent Raman frequency model for monoatomic crystals
摘要： In the present study, a theoretical model for the temperature dependence of Raman frequency shift without any adjustable parameters is established. The model builds a relationship between the temperature dependent Raman frequency and the Raman frequency at a reference temperature. To verify the present model, the temperature dependent Raman frequency shifts of Ge, α-Sn, and Si are predicted, which are in excellent agreement with the available experimental results, Balkanski’s theory and Kolesov’s theory. Besides, the model indicates that the variations in special heat with temperature determine the temperature dependent Raman frequency. This work can provide a convenient method to predict the temperature dependent Raman frequency shift for monoatomic crystals.
关键词： Raman frequency shift,semiconductor,temperature dependent,modelling
更新于2025-09-23 15:21:01
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Modeling of surface spectra with and without dust from Martian infrared data: new aspects
摘要： Purpose – This paper aims to characterize the mineral composition of Martian surfaces based on Thermal Emission Spectrometer (TES; Mars Global Surveyor) as measured in the infrared thermal range. It presents modeling and interpreting of TES spectral data from selected Martian regions from which the atmospheric influences had been removed using radiative transfer algorithm and deconvolution algorithm. The spectra from the dark area of Cimmeria Terra and the bright Isidis Planitia were developed in Philip Christensen’s and Joshua Bandfield’s publications, where these spectra were subjected to spectral deconvolution to estimate the mineral composition of the Martian surface. The results of the analyses of these spectra were used for the modeling of dusty and non-dusty surface of Mars. As an additional source, the mineral compositions of Polish basalts and mafic rocks were used for these surfaces as well as for modeling Martian meteorites Shergottites, Nakhlites and Chassignites. Finally, the spectra for the modeling of the Hellas region were obtained from the Planetary Fourier Spectrometer (PFS) – (Mars Express) and the mineralogical compositions of basalts from the southern part of Poland were used for this purpose. The Hellas region was modeled also using simulated Martian soil samples Phyllosilicatic Mars Regolith Simulant and Sulfatic Mars Regolith Simulant, showing as a result that the composition of this selected area has a high content of sulfates. Linear spectral combination was chosen as the best modeling method. The modeling was performed using PFSLook software written in the Space Research Centre of the Polish Academy of Sciences. Additional measurements were made with an infrared spectrometer in thermal infrared spectroscopy, for comparison with the measurements of PFS and TES. The research uses a kind of modeling that successfully matches mineralogical composition to the measured spectrum from the surface of Mars, which is the main goal of the publication. This method is used for areas where sample collection is not yet possible. The areas have been chosen based on public availability of the data.
关键词： Spectra modelling,Infrared spectrometry,Linear spectral addition,Mars
更新于2025-09-23 15:21:01