Through Holes Research Articles

An Accordion-Folding Series-Fed Patch Array With Finite Thickness: A folding technique for CubeSat arrays

Combining antenna arrays with physical reconfigurability (i.e., origami) allows for additional degrees of freedom in operation and enables larger structures to be folded into smaller volumes. The packaging ability of origami antennas is of great interest for CubeSat applications in particular. However, traditional origami is based on the manipulation of thin sheets, making physical reconfigurability with thick substrates very difficult. In this article, we present a foldable series-fed patch array designed on a strictly rigid printed circuit board (PCB). Notably, the array does not require any external mechanical folding appendages (i.e., brackets, tapes, or offsets), and it can be manufactured using commercially available PCBs and equipment. The PCB itself is strategically cut to form lamina emergent torsion (LET) joints. When fully deployed, the array operates at 5.7 GHz. A significant shift is not seen in the operational frequency until the folding exceeds 60° (5.7–5.61 GHz). This shows that the array, even in a state of near extreme faulty deployment, will operate as intended. An 8 × 6 prototype array was fabricated using a Rogers DiClad 880. When fully deployed, the array is extended in a surface area of 280 × 198 × 1.524 mm and can be folded into a 35.5 × 198 × 12.5-mm compartment. The array held its integrity well after 100 cycles. (One cycle starts at a state of full deployment, moves to a state of being fully packaged, and goes back to a state of full deployment.) Measurements show that the active reflection coefficients are in good agreement with the finite array simulations. The measured realized gains at 5.7 GHz for 0° and 30° folds were 22.4 and 21.4 dBi, respectively. At the 60° fold, a realized gain of 20.6 dBi was achieved at the frequency of 5.61 GHz.

Broadband insertion loss measurement of flexible copper clad laminate with direct metallization

Broadband insertion loss measurement of flexible copper clad laminate with direct metallization

Embedded System for the Simultaneous Study of SAHS and Cardiac Arrhythmia

This paper presents a proposed embedded system for the simultaneous study of Sleep Apnea/Hypopnea Syndrome (SAHS) and related cardiac arrhythmias, which can affect about 1 billion people worldwide. Its objective is to become a tool to research the relational causes of these disruptions. It can record biomedical signals and vital parameters related to cardiac and respiratory activity commonly used in clinical practice. The system is designed to be used in sleep studies, providing greater comfort to users by integrating two devices into one. The proposed system is battery-powered and has Bluetooth wireless communication for remote studies. The design is based on specific electronic components such as Analog Front-End and System on Chips, and best-practice guidelines for PCB design were followed. A hybrid-scheduler was selected as software architecture to ensure the task execution at specific intervals. The systems signal quality recording sub-system was tested using a multiparametric simulator, commercial holter device and acquired real records. The results are similar to other works.

Heavy Metals in Surface Sediments of the Coastal Area Around Daerah Istimewa Yogyakarta, Indonesia: Their Relations to Land-Use Types

The province of Daerah Istimewa Yogyakarta (DIY) has experienced significant changes in urbanization, industry, and tourism, making it one of Indonesia's fastest-growing areas. Increased anthropogenic activity in the coastal region may cause heavy metal contamination in that zone to grow. Based on different land-use types, this study examined the distribution of heavy metals, namely cadmium (Cd), lead (Pb), copper (Cu), and zinc (Zn), in surface sediment. It assessed the feasibility of sediment quality standards based on the Canadian Sediment Quality Guidelines (CSQG). Nine stations made up the sampling site, each representing a different land-use type, including mangrove ecosystem, tourist attraction, airport, harbor, mining area, bare land, shrimp pond, agricultural land, and settlement. The concentrations of Cd in bare land, shrimp pond, agricultural land, and settlement (with values of 2.707, 2.955, 2.983, and 2.873, respectively), and Cu in the mangrove ecosystem (with values of 42.893) slightly exceeded the corresponding Threshold Effect Level (TEL) value of CSQG. Meanwhile, the content of other heavy metals in all land use types tends to be low, even below the Limit of Detection (LOD). The data on the level of heavy metal pollution in the study area shows no connection between heavy metal contamination and different land-use types. It is brought on by a variety of circumstances, such as the fact that human activity in the study area did not significantly contribute to heavy metal contamination or that heavy metals were contaminated and then spread to other forms of land-use types, in this case, the mangrove ecosystem, by runoff and wind. This is because variations in salinity, estuary flushing, physical mixing and dilution, and chemical processes, including sorption, complexation, cation exchange, and redox reactions, all affect how heavy metals are transported by water. The government should create environmental regulations, laws, quality norms and standards, more funding for cutting-edge scientific research, and technical tools to prevent heavy metal pollution in coastal areas.

Joint denoising method of seismic velocity signal and acceleration signals based on independent component analysis

The signal-to-noise ratio (SNR) of seismic data is the key to seismic data processing, and it also directly affects interpretation of seismic data results. The conventional denoising method, independent variable analysis, uses adjacent traces for processing. However, this method has problems, such as the destruction of effective signals. The widespread use of velocity and acceleration geophones in seismic exploration makes it possible to obtain different types of signals from the same geological target, which is fundamental to the joint denoising of these two types of signals. In this study, we propose a joint denoising method using seismic velocity and acceleration signals. This method selects the same trace of velocity and acceleration signal for Independent Component Analysis (ICA) to obtain the independent initial effective signal and separation noise. Subsequently, the obtained effective signal and noise are used as the prior information for a Kalman filter, and the final joint denoising results are obtained. This method combines the advantages of low-frequency seismic velocity signals and high-frequency and high-resolution acceleration signals. Simultaneously, this method overcomes the problem of inconsistent stratigraphic reflection caused by the large spacing between adjacent traces, and improves the SNR of the seismic data. In a model data test and in field data from a work area in the Shengli Oilfield, the method increases the dominate frequency of the signal from 20 to 40 Hz. The time resolution was increased from 8.5 to 6.8 ms. The test results showed that the joint denoising method based on seismic velocity and acceleration signals can better improve the dominate frequency and time resolution of actual seismic data.

1-(2-Pyridylazo)-2-naphthol as a synergistic additive for improving throwing power of through hole copper electronic electroplating

In this work, we develop a novel 1-(2-Pyridylazo)-2-naphthol (PAN)-based acidic sulfate copper electronic electroplating process for compact, homogeneous and conformal copper thickening of through hole (TH). The adsorption characteristics, electrochemical properties and the interaction mechanisms of three additives (PEG, SPS and PAN) are studied in detail. Scanning electron microscope (SEM) and optical microscope (OM) reveal that PAN can make the copper coating in fine grains and high throwing power of 90.35% in TH without an overhang phenomenon. Theoretical calculations illustrate that the binding energies between additive molecules and copper surface decrease in the order: PAN > SPS > PEG. Cyclic voltammetry experiments at rotating rates of 1200 and 200 r/min prove that PAN itself can accelerate and weakly suppress copper electrodeposition at the center and mouth of TH, respectively. PAN behaves respectively the synergistic and antagonistic effects with PEG at the mouth and center of TH, and the weakly synergistic effects with SPS both at the mouth and center of TH. The addition of PAN to the virgin make-up solution (VMS) containing PEG and SPS causes decreasing the relative electric charge (ΔQ) at high and low rotating rates from 18.52 ± 0.08% to 8.25 ± 0.05%, which satisfies the closer copper electronic electroplating rate at the center and mouth of TH. The effective and complicated synergistic effects of the additives PEG, SPS and PAN can achieve compact, homogeneous and conformal copper thickening of TH.

Pontus: Finding Waves in Data Streams

The bumps and dips in data streams are valuable patterns for data mining and networking scenarios such as online advertising and botnet detection. In this paper, we define the wave, a data stream pattern with a serious deviation from the stable arrival rate for a period of time. We then propose Pontus, an efficient framework for wave detection and estimation. In Pontus, a lightweight data structure is utilized for the preliminary processing of incoming packets in the data plane to take advantage of its high processing speed; then, the powerful control plane carries out computationally intensive wave detection and estimation. In particular, we propose the Multi-Stage Progressive Tracking strategy which detects waves in stages and removes any disqualified items promptly to save memory. Hash collisions are addressed by a Stage Variance Maximization technique to reduce estimation error. Moreover, we prove the theoretical error bound and establish upper bounds of false positive and false negative. Experiment results show that the software version of Pontus can achieve around 97% F1-Score even under scarce memory when baselines fail. Furthermore, the implemented prototype of Pontus based on P4 achieves 842x higher throughput than the baseline strawman solution.

Comparing Performance of Spectral Image Analysis Approaches for Detection of Cellular Signals in Time-Lapse Hyperspectral Imaging Fluorescence Excitation-Scanning Microscopy.

Hyperspectral imaging (HSI) technology has been applied in a range of fields for target detection and mixture analysis. While HSI was originally developed for remote sensing applications, modern uses include agriculture, historical document authentication, and medicine. HSI has also shown great utility in fluorescence microscopy. However, traditional fluorescence microscopy HSI systems have suffered from limited signal strength due to the need to filter or disperse the emitted light across many spectral bands. We have previously demonstrated that sampling the fluorescence excitation spectrum may provide an alternative approach with improved signal strength. Here, we report on the use of excitation-scanning HSI for dynamic cell signaling studies-in this case, the study of the second messenger Ca2+. Time-lapse excitation-scanning HSI data of Ca2+ signals in human airway smooth muscle cells (HASMCs) were acquired and analyzed using four spectral analysis algorithms: linear unmixing (LU), spectral angle mapper (SAM), constrained energy minimization (CEM), and matched filter (MF), and the performances were compared. Results indicate that LU and MF provided similar linear responses to increasing Ca2+ and could both be effectively used for excitation-scanning HSI. A theoretical sensitivity framework was used to enable the filtering of analyzed images to reject pixels with signals below a minimum detectable limit. The results indicated that subtle kinetic features might be revealed through pixel filtering. Overall, the results suggest that excitation-scanning HSI can be employed for kinetic measurements of cell signals or other dynamic cellular events and that the selection of an appropriate analysis algorithm and pixel filtering may aid in the extraction of quantitative signal traces. These approaches may be especially helpful for cases where the signal of interest is masked by strong cellular autofluorescence or other competing signals.

Cell lineage analysis reveals signal tracing and compartment characterisation in Drosophila haltere.

Insect halteres, as specialised hind wings, play an important role during aerial manoeuvres. In Drosophila, halteres and wings are homologous appendages with different morphology. Previous studies have focused on the metamorphosis of halteres, while current knowledge about its cell lineage and regional compartmentalization is still limited. In this study, we performed cell-lineage tracing of canonical landmark signals in halteres and present a simple model for haltere development. Cell lineage tracing in wings was used as a reference. The nub showed wing-like expressions in halteres, whereas hth and pnr exhibited different expressions in adult wings and halteres. The lineage tracing revealed that the pouch region gives rise to end-bulb, and hinge cells contribute to proximal haltere formation. Moreover, we demonstrated that twi-expressing cells participate in the cell population of the distal end-bulb. Haematoxylin and eosin staining indicated that muscle cells were present at the distal end-bulb. These results indicated that adult halteres displayed unique cell lineage patterns and the muscle cells are important components of end-bulbs.

A Sensitive Response Index Selection for Rapid Assessment of Heavy Metals Toxicity to the Photosynthesis of Chlorella pyrenoidosa Based on Rapid Chlorophyll Fluorescence Induction Kinetics.

Heavy metals as toxic pollutants have important impacts on the photosynthesis of microalgae, thus seriously threatening the normal material circulation and energy flow of the aquatic ecosystem. In order to rapidly and sensitively detect the toxicity of heavy metals to microalgal photosynthesis, in this study, the effects of four typical toxic heavy metals, chromium (Cr(VI)), cadmium (Cd), mercury (Hg), and copper (Cu), on nine photosynthetic fluorescence parameters (φPo, ΨEo, φEo, δRo, ΨRo, φRo, FV/FO, PIABS, and Sm) derived from the chlorophyll fluorescence rise kinetics (OJIP) curve of microalga Chlorella pyrenoidosa, were investigated based on the chlorophyll fluorescence induction kinetics technique. By analyzing the change trends of each parameter with the concentrations of the four heavy metals, we found that compared with other parameters, φPo (maximum photochemical quantum yield of photosystem II), FV/FO (photochemical parameter of photosystem II), PIABS (photosynthetic performance index), and Sm (normalized area of the OJIP curve) demonstrated the same monotonic change characteristics with an increase in concentration of each heavy metal, indicating that these four parameters could be used as response indexes to quantitatively detect the toxicity of heavy metals. By further comparing the response performances of φPo, FV/FO, PIABS, and Sm to Cr(VI), Cd, Hg, and Cu, the results indicated that whether it was analyzed from the lowest observed effect concentration (LOEC), the influence degree by equal concentration of heavy metal, the 10% effective concentration (EC10), or the median effective concentration (EC50), the response sensitivities of PIABS to each heavy metal were all significantly superior to those of φRo, FV/FO, and Sm. Thus, PIABS was the most suitable response index for sensitive detection of heavy metals toxicity. Using PIABS as a response index to compare the toxicity of Cr(VI), Cd, Hg, and Cu to C. pyrenoidosa photosynthesis within 4 h by EC50 values, the results indicated that Hg was the most toxic, while Cr(VI) toxicity was the lowest. This study provides a sensitive response index for rapidly detecting the toxicity of heavy metals to microalgae based on the chlorophyll fluorescence induction kinetics technique.

Levels of heavy metal in soil and vegetable and associated health risk in peri-urban areas across China

Peri-urban vegetable field plays an essential role in providing vegetables for local residents. Because of its particularity, it is affected by both industrial and agricultural activities which have led to the accumulations of heavy metal in soil. So far, information on heavy metal pollution status, spatial features, and human health risks in peri-urban vegetable areas across China is still scarce. To fill this gap, we systematically compiled soil and vegetable data collected from 123 articles published between 2010 and 2022 at a national level. The pollution status of heavy metals (i.e., cadmium (Cd), mercury (Hg), arsenic (As), lead (Pb), chromium (Cr), copper (Cu), nickel (Ni), and zinc (Zn)) in peri-urban vegetable soils and vegetables were investigated. To evaluate the levels of heavy metal pollution in soil and human health risks, the geoaccumulation index (Igeo) and target hazard quotient (HQ) were calculated. The results showed that mean concentrations of Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn in peri-urban vegetable soils were 0.50, 0.53, 12.03, 41.97, 55.56, 37.69, 28.55, and 75.38 mg kg−1, respectively. The main pollutants in peri-urban vegetable soil were Cd and Hg, and 85.25% and 92.86% of the soil samples had Igeo > 1, respectively. The mean Igeo values of this regions followed the order of northwest > central > south > north > east > southwest > northeast for Cd and northeast > northwest > north > southwest > east > central > south for Hg. The mean Cd, Hg, As, Pb, Cr, Cu, Ni, and Zn concentrations in vegetables were 0.30, 0.26, 0.37, 0.54, 1.17, 6.17, 1.96, and 18.56 mg kg−1, respectively. Approximately 87.01% (Cd), 71.43% (Hg), 20% (As), 65.15% (Pb), 27.08% (Cr) of the vegetable samples exceeded the safety requirement values. The vegetables grown in central, northwest, and northern China accumulated much more heavy metals than those grown in other regions. As the HQ values for adults, 53.25% (Cd), 71.43% (Hg), 84.00% (As), and 58.33% (Cr) of the sampled vegetables were higher than 1. For children, the HQ values were higher than 1 for 66.23% (Cd), 73.81% (Hg), 86.00% (As), and 87.50% (Cr) of the sampled vegetables. The findings of this study demonstrate that the situation of heavy metal pollution in peri-urban vegetable areas across China are not optimistic and residents who consume the vegetables are at high risk of health issues. To ensure soil quality and human health, strategies should be taken to guide vegetable production and remedy soil pollution in peri-urban areas with the rapidly urbanizing China.

Distribution of heavy metals in coastal sediments under the influence of multiple factors: A case study from the south coast of an industrialized harbor city (Tangshan, China)

This research investigated the spatial distribution of heavy metals, including mercury (Hg), cadmium (Cd), copper (Cu), arsenic (As), nickel (Ni), lead (Pb), chromium (Cr), and zinc (Zn), in surface sediments from a coastal area near to an industrial harbor (Tangshan Harbor, China) using 161 sediment samples. According to the geo-accumulation index (Igeo), 11 samples were classified as unpolluted (Igeo≤0). Notably, 41.0 % of the research samples were moderately or strongly polluted (2 < Igeo≤3) with Hg and 60.2 % of the samples were moderately polluted (1 < Igeo≤2) in Cd. The ecological effect evaluation showed that the metals Zn, Cd, and Pb were at the effect range low level, and 51.6 % of the samples for Cu, 60.9 % for Cr, 90.7 % for As, 41.0 % for Hg, and 64.0 % for Ni fell in the range between the effect range-low and the effect range-mean levels, respectively. The correlation analysis showed that the distribution patterns of Cr, Cu, Zn, Ni, and Pb were similar to each other, high in the northwest, southeast, and southwest regions of the study area and low in the northeast region, which corresponded well with sediment size components. Based on principal component analysis (PCA) and positive matrix factorization (PMF), four distinct sources of pollution were quantitatively attributed, including agricultural activities (22.08 %), fossil fuel consumption (24.14 %), steel production (29.78 %), and natural sources (24.00 %). Hg (80.29 %), Cd (82.31 %) and As (65.33 %) in the region's coastal sediments were predominantly contributed by fossil fuel, steel production and agricultural sources, respectively. Cr (40.00 %), Cu (43.63 %), Ni (47.54 %), and Zn (38.98 %) were primarily of natural lithogenic origin, while Pb mainly came from the mixed sources of agricultural activities (36.63 %), fossil fuel (36.86 %), and steel production (34.35 %). Multiple factors played important roles in the selective transportation of sedimentary heavy metals, particularly sediment properties, and hydrodynamic sorting processes in the study area.

Electronic structure, thermodynamics, and thermoelectric properties of YxAl1−xN semiconductor alloys for new promising optoelectronics and energy conversion: Ab Initio study

Key characteristics such as structural, electronic, thermodynamic, and thermoelectric of wurtzite yttrium aluminum nitride (YxAl1−xN) semiconductor alloys (with 0≤ x ≤ 0.375) were investigated using Ab Initio density functional simulation within powerful full-potential linear augmented plane wave (FP‒LAPW) method. The equilibrium structural parameters (a0, c0, c0/a0,V0) were determined using the revised GGA−PBEsol approach in perfect agreement with experiments. The lattice a0-parameter varies almost linearly with yttrium concentration with a bowing of −0.08597 Å, while the c0-parameter has a bowing of −0.5715 Å. The lattice dynamics of doped YxAl1−xN systems were analyzed based on formation energy and phonon frequencies. Electronic structures of wurtzite YxAl1−xN described from a modern nKTB−mBJ potential show bandgap engineering with a range of [6.10 eV–3.85 eV] for x varies from 0 to 0.375, covering emission wavelengths [203 nm–322 nm] in the ultraviolet spectrum. The electron charge density contours indicate ionic bonding in wurtzite YxAl1−xN. Using the quasi-harmonic Debye model, thermodynamic properties of YxAl1−xN alloys, including volume (V0), mass modulus (B0), specific heat (Cv), thermal expansion (α), entropy (S), Debye temperature (ΘD) and Grüneisen parameter (γ), were calculated and analyzed under temperature and pressure effects. Moreover, electronic transport properties, such as the Seebeck coefficient (S), electrical conductivity (σ/τ), power factor, thermal conductivity (κel/τ), and figure of merit (ZT), of YxAl1−xN alloys were determined using BoltzTraP code. YxAl1−xN (at x = 0.25 and T = 600 K) exhibited the largest magnitude of S, with a value of ∼213.9 μV/K, and ZT ∼ 0.72. It also had the lowest value of κ/τ ∼9.9 × 1013 W m−1.K−1.s−1. Wurtzite YxAl1−xN crystal appears to be an extremely interesting candidate for potential applications in optoelectronics (UV) and future green energy system.

Moisture sensitivity and heavy metal leaching potentials of asphalt mixtures incorporating rubber modifiers and wax-based admixture

Moisture damage is one of the most frequent damages that occurs on asphalt pavements. The application of rubberized materials for asphalt is widely acceptable due to cost saving and environmentally friendly. The purpose of this study is to assess the performance of rubberized asphalt mixtures containing wax-based admixture, namely Tough Fix Hyper (TFH), in terms of moisture sensitivity and hazardous compound leaching potential. The moisture absorption, chemical immersion, and boiling water tests were used to assess the resistance to moisture damage on aggregate-binder bonding characteristics. Following that, the trend of moisture sensitivity was evaluated through an image analysis procedure. To simulate the environmental impact of leaching, the toxicity characterization leaching procedure (TCLP) test was adopted. The results showed that interaction between the crumb rubber or latex with TFH decreases the stripping value of the mixes significantly based on the chemical immersion test. Furthermore, the image analysis of the samples subjected to boiling water conditioning showed that pixels of asphalt samples without TFH, ranging from 524,949 to 472,346, decrease from 520,870 to 289,070, indicating that the asphalt remained coated area improved by 67.70–91.39%. The analysis of the leachate test revealed that the heavy metals, including arsenic (As), nickel (Ni), copper (Cu), chromium (Cr), vanadium (V), and cadmium (Cd), were not detected. However, zinc (Zn) was detected in the modified mixture, ranging from 0.05 to 0.114 mg/L, which lies within the allowable norm. In conclusion, the incorporation of crumb rubber and TFH in asphalt mixtures poses no environmental risk.

First-Principles Study on IMC Formation and Interface Failure of Electronic Packaging Solder Joints

At present, Sn-3.0Ag-0.5Cu (SAC305) solder is one of the commonly used lead-free solders, and copper-clad laminate is the commonly used PCB substrate. SAC solder and copper substrate mainly generate two intermetallic compounds (IMCs) of Cu6Sn5 and Cu3Sn during the soldering process. Based on the first principles, this paper analyzes the formation difficulty of the two kinds of IMCs generated in the soldering, and the failure mechanism of the Sn/IMC and IMC/Cu interfaces. Firstly, based on the density functional theory (DFT), the “CASTEP” module in Material Studio (MS) is used to analyze the formation difficulty of the two IMCs from the point of the density of states, population analysis, and energy. The results show that Cu6Sn5 is easier to generate, which also explains the reason for the first generation of Cu6Sn5 in the initial stage of soldering. Then, Sn / IMC and IMC / Cu interfaces were established in MS, and the reason why solder joint failure mainly occurred at the Sn / IMC interface was explained by energy analysis.

Manufacturability Analysis and Research of PCB Component Mounting

In the traditional production mode, the disconnection between PCB design and manufacturing leads to many disadvantages such as more design rework, difficult processing, and high cost. To address this issue, this paper achieves manufacturability analysis at the PCB design stage by establishing a manufacturability analysis system for PCB component placement and simulating the placement process of the placement machine on the computer, taking into account the functional and process requirements of PCB board-level circuits simultaneously, so as to facilitate design decisions in the global tendency of the PCB manufacturing system to be optimal.

Thermodynamic quasi-equilibria in high power magnetron discharges: a generalized Poisson–Boltzmann relation

The Poisson–Boltzmann (PB) equation is a nonlinear partial differential equation that describes the equilibria of conducting fluids. Using a thermodynamic variational principle based on the balances of particle number, entropy, and electromagnetic enthalpy, it can also be justified for a wide class of unmagnetized technological plasmas (Köhn et al 2021 Plasma Sources Sci. Technol. 30 105014). This study extends the variational principle and the resulting PB equation to high power magnetron discharges as used in planar high power pulsed magnetron sputtering. The example in focus is that of a circular high power magnetron. The discharge chamber and the magnetic field are assumed to be axisymmetric. The plasma dynamics need not share the symmetry. The domain is split into the ionization region close to the cathode where electrons are confined, i.e. can escape from their magnetic field lines only by slow processes such as drift and diffusion, and the outer region , where the electrons are largely free and the plasma is cold. With regard to the dynamics of the electrons and the electric field, a distinction is made between a fast thermodynamic and a slow dissipative temporal regime. The variational principle established for the thermodynamic regime is similar to its counterpart for unmagnetized plasmas but takes magnetic confinement explicitly into account by treating the infinitesimal flux tubes of as individual thermodynamic units. The obtained solutions satisfy a generalized PB relation and represent thermodynamic equilibria in the fast regime. However, in the slow regime, they must be interpreted as dissipative structures. The theoretical characterization of the dynamics is corroborated by experimental results on high power magnetrons published in the literature. These results are briefly discussed to provide additional support.

Effect of molecular weight on properties of polyarylene ether nitrile‐based flexible copper clad laminate

AbstractA series of Polyarylene ether nitriles (PENs) with different molecular weights were synthesized and studied the effect of molecular weight size on the performance of PEN and PEN‐based flexible copper clad laminate (FCCL). It shows that these PENs have excellent thermal properties with Tg &gt; 200°C, T5% &gt; 500°C, and a long service life at 200°C (2.64 × 103 min, 95 wt% of the residual weight). The tensile mechanical properties of PENs increase gradually as the molecular weight of PENs increases, and the water absorption decreases with the increasing molecular weight of PENs. However, the peer strength of FCCL showed an opposite trend compared to the tensile properties of pure PEN, and the PEN‐2 shows the largest peer strength of 12.79 N/cm. Combining the thermal properties, mechanical properties, water absorption rate of PENs, and the peel strength and flexibility of FCCL, PEN‐2 is considered to be the most suitable for FCCL.

Wearable Rectenna With Integrated Miniaturized Feeding Slot and Rectifier Structure

A low-cost hybrid textile/PCB wearable rectenna is designed for smart on-body applications. It is an integration of a textile patch antenna and a highly efficient rectifier on a small PCB substrate, where the feeding aperture of the antenna is significantly miniaturized by exploiting an LC loading technique in order to have an effective integration with the rectifier. The feeding-rectifying circuitry is attached to the back of the antenna by normal sewing threads. The essential components are soldered on the small rigid PCB for a robust connection. The size of the rectenna is 0.817 × 0.817 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> while the rigid substrate area for the feeding-rectifying circuitry is only 0.278 × 0.147 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (3.4 cm × 1.8 cm) at 2.45 GHz. The intrinsic dielectric/conduction loss of textile feedlines, the loss of antenna-to-rectifier interconnectors, the loss of soldering or gluing on textiles, and the loss due to body absorption from typical large feeding slots are constitutively reduced. The soldering points and the consequent hard-to-be-characterized parasitic effects on textiles are avoided. The proposed integration approach reduces the cost and eases the rectenna design, fabrication, and integration. As a result, the power conversion efficiency (PCE) of the rectifier reaches up to 39.5% at -20 dBm input power level whilst the experimental rectenna prototype achieves the state-of-the-art PCE of 41% at an extremely low incident power density of 0.4 μW/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The maximum PCE is 56% at the -5 dBm input power. Finally, the possibility of harvesting datalink energy from PC/mobile phones as power source for wearable electronics is investigated.

Obscuring Environment and X-Ray Variability of Compact Symmetric Objects Unveiled with XMM-Newton and NuSTAR

Compact symmetric objects (CSOs) show radio features such as jets, lobes, and hot spots, which are contained within their host galaxies, and likely represent a recent radio activity. A subpopulation of CSOs with high intrinsic X-ray column densities has been inferred from shallow, soft X-ray band exposures, and observed to cluster in the linear radio size versus 5 GHz radio power plane, which suggests that a dense circumnuclear medium may dramatically influence the growth of compact radio structures. Here, we report on the first detection of two CSOs, 2021+614 and J1511+0518, at energies above 10 keV with NuSTAR. We model the NuSTAR data jointly with the new XMM-Newton data of J1511+0518, and with the archival XMM-Newton data of 2021+614. A toroidal reprocessor model fits the data well and allows us to robustly confirm the X-ray properties of the CSO absorbers and continuum. In both sources, we find intrinsic X-ray absorbing column densities in excess of 1023 cm−2, hard photon indices of the primary emission, Γ ∼ 1.4–1.7, Fe Kα line emission, and variability of the intrinsic X-ray flux density on the timescale of years. The studied X-ray continua are dominated by the primary power-law emission at energies above 3 keV, and by the scattered component at energies below 3 keV. An additional soft X-ray component, modeled with a hot, collisionally ionized plasma with temperature kT ∼ 1 keV, is required by the XMM-Newton data in J1511+0518, which is corroborated by the tentative evidence for the extension in the archival Chandra image of the source.