MW Range Research Articles

Paleoseismologic evidence for large-magnitude (Mw7.5–8.0) earthquakes on the Ventura blind thrust fault: Implications for multifault ruptures in the Transverse Ranges of southern California

Detailed analysis of continuously cored boreholes and cone penetrometer tests (CPTs), high-resolution seismic-reflection data, and luminescence and 14C dates from Holocene strata folded above the tip of the Ventura blind thrust fault constrain the ages and displacements of the two (or more) most recent earthquakes. These two earthquakes, which are identified by a prominent surface fold scarp and a stratigraphic sequence that thickens across an older buried fold scarp, occurred before the 235-yr-long historic era and after 805 ± 75 yr ago (most recent folding event[s]) and between 4065 and 4665 yr ago (previous folding event[s]). Minimum uplift in these two scarp-forming events was ∼6 m for the most recent earthquake(s) and ∼5.2 m for the previous event(s). Large uplifts such as these typically occur in large-magnitude earthquakes in the range of Mw 7.5–8.0. Any such events along the Ventura fault would likely involve rupture of other Transverse Ranges faults to the east and west and/or rupture downward onto the deep, low-angle décollements that underlie these faults. The proximity of this large reverse-fault system to major population centers, including the greater Los Angeles region, and the potential for tsunami generation during ruptures extending offshore along the western parts of the system highlight the importance of understanding the complex behavior of these faults for probabilistic seismic hazard assessment.

PEM Electrolysis: Ready for Impact

The need for energy storage has never been so pressing; due to the increased proliferation and intermittent nature of wind and solar power sources, many regional grids can no longer accept more of these sources. Electrolysis of water using polymer electrolyte membranes (PEMs) has long held the promise of large-scale energy storage, needing only the simplest of reactants, water. The adoption of PEM electrolyzers has been impeded due to the headwinds of high capital cost, poor efficiency, and unknown reliability. Numerous incremental improvements, and increasing economies of scale over the past 10 years have led to very large decreases in the cost of PEM electrolysis. Increasing operating temperature has had the largest impact on efficiency and output. Subsequently, whereas only a few years ago there were no commercial PEM electrolyzer stacks in the 1 MW range, today at least five companies are at or near launch of MW electrolyzer systems.

PEM Electrolysis: Ready for Impact

The need for energy storage has never been so pressing; due to their increasing proliferation and the intermittent nature of wind and solar power sources, many regional grids can no longer accept more of these sources. Electrolysis of water using polymer electrolyte membranes (PEMs) has long held the promise of large-scale energy storage, needing only the simplest of reactants, water. More importantly it is perfectly suited for storing excess energy from these sources as they can handle tremendously high ramp rates as well as many start-stop cycles. The adoption of PEM electrolyzers has been impeded due to the headwinds of high capital cost, (including expensive high precious metal content), poor efficiency, and the empty promises made by the hydrogen economy from many years. Numerous incremental improvements, and increasing economies of scale over the past 10 years have led to very large decreases in the cost of PEM electrolysis. The complexity of the electrolyzer stack and precious metal content have been decreased, while simultaneously increasing lifetime. Increasing operating temperature has had the largest impact on efficiency and output, while improved membrane supports have allowed for higher differential pressures; reducing the need and cost of ancillary systems (see Figure 1). These advances have had the combined effect of reducing the cost of hydrogen from PEM electrolysis by nearly an order of magnitude, allowing it to approach the cost of pumped hydro, the standard in large-scale energy storage. Subsequently, whereas only a few years ago there were no commercial PEM electrolyzer stacks in the 1 MW range, today no fewer than five companies are at or near launch of MW electrolyzer systems. Figure 1. Total cost of hydrogen as a function of plant size and operating current Figure 1

Improved reconstitution of Trizol derived protein extracts provides high quality samples for comprehensive proteomic characterization of cell cultures

Background: The study of RNA, DNA, and protein from the same sample is a great advantage but can be challenging. Using Trizol, one can simultaneously extract RNA, DNA, and protein, leading to efficient sample use and more comprehensive analysis. Although it is used routinely for RNA extraction, the frequency of use of Trizol extracts for proteomics applications is low. The aim of our study was to evaluate the results of a simple modification to the Trizol protocol in terms of extraction and protein recovery efficacy and compatibility of the extracts with proteomics technologies in comparison to our standard extraction protocol including freeze/thaw cycles in urea/ thiourea. Method: We used the human airway epithelial cell line S9 and extracted proteins either with a modified Trizol protocol or by freeze/thaw cycles in 8M urea/ 2M thiourea. Extracted proteins were quantified and subjected to 1D- and 2D-gel electrophoresis, Western Blotting and LC-coupled tandem mass spectrometry analysis. Results: Compared to urea/ thiourea extraction, the Trizol-extracted proteins exhibited a similar protein composition and identification rate in LC-coupled tandem mass spectrometry experiments. 1D- and 2D-PAGE of Trizol-extracted proteins revealed excellent protein resolution with better coverage of proteins in the low MW range than urea/ thiourea extraction. Conclusion: The modified Trizol-protocol enabled excellent protein extraction from cell culture samples and high compatibility with proteomics technologies, especially with LC-tandem mass spectrometry.

Atomic Layer Deposition of SnO2 for Selective Room Temperature Low Ppb Level O3 Sensing

Ozone sensing is particularly interesting as exposure has been shown to be very harmful to human health. Ozone exposure has been associated with an increased risk of developing respiratory disease, inflammation of airways and increased response to allergens. Individuals suffering from respiratory diseases such as asthma are particularly sensitive to ozone and both short and long term exposures can induce undesirable effects on the human condition [1-4] and ozone concentrations have increased strongly in highly populated areas over the past decade [2,5]. Key challenges in metal oxide sensors are high power consumption associated with high operating temperatures and lack of selectivity as the sensors tend to respond broadly to many different gases. In this study we demonstrate low power and selective ozone sensors using SnO2 metal oxide thin film gas sensors produced by Atomic Layer Deposition (ALD). ALD enables precise film thickness control and conformal coating tailoring of film thickness to the Debye length, enhancing depletion region effects and increasing surface to volume ratios for enhanced sensitivity at lower temperatures. SnO2 films were deposited via ALD using tetrakis dimethylamino tin precursor and ozone reactant on SiO2/Si substrates. The films were annealed in atmosphere or inert ambient at 400C for 30 minutes and were then patterned for lift off using standard photolithography. Ten nm of titanium were used for an adhesion layer followed by 150 nm of Au. The SnO2 deposition rate was characterized with variable angle spectroscopic ellipsometry and determined to be 1.1 A/cycle. X-ray photoelectron spectroscopy and X-ray diffraction were used to evaluate the film properties. Ozone testing was done using custom built testing chamber and a Teledyne T700U gas calibration system equipped with a UV ozone generator and photometer feedback for precision concentrations. Resistance measurements were made during gas exposure using a Keithley 4200 semiconductor parameter analyzer. We have characterized our ALD SnO2 process and film properties. XRD confirmed rutile phase of the film after 400C anneal for 30 minutes as shown in Figure 1. Ozone exposure resulted in increased resistance of the SnO2 films and response was demonstrated for various concentrations at room temperature resulting in ozone detection at several microwatts of power. Response to concentrations from 50-150 ppb can be seen in figure 2, and to 400 ppb in figures 3 and 4. It is found that the recovery of the SnO2 sensors is related to the film thickness. Films of 12 nm of SnO2 demonstrated extremely slow recovery while films of 6 nm recovered more quickly even at room temperature as shown in Figures 3 and 4. The recovery process can be expedited by the addition of thermal energy to aid in ozone desorption but low power applications at room temperature can take advantage of both of these modes of operation. Thicker sensors with slow recovery may be useful in measuring dose of ozone over time for asthmatics and other health conscious users while the thinner films may be better suited toward instantaneous concentration quantification. Both sensors offer faster response and recovery with increasing temperature enabling trading off of power needs with sensor response but room temperature operation offers yet another advantage. Without any added thermal energy, our films respond to tens of ppb of ozone while not responding to hundreds of ppb of NO2 or ppm of CO, typical concentration found in the environment. Response to each of these gases can be seen in Figures 5 and 6. Sensor reset can be accomplished with periodic thermal cycles to maintain low power levels and selectivity advantages of room temperature operation. In summary, we have demonstrated room temperature SnO2 gas sensor deposited by ALD method. It was observed that the ALD SnO2 gas sensor enables sensitivity to ozone in the 50-400ppb range with selectivity toward NO2 and CO, common interfering gases in the environment. It was also shown that our SnO2 sensor operates at room temperature and hence the total power consumption reduces to mW range that is feasible for wearable sensor system. Figure 1

Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source.

We present an ultrahigh-speed optical coherence tomography (OCT) based on an all-optical swept-source with an A-scan rate of 40 MHz. The inertia-free swept-source, which has its output power of 41.2 mW and tuning range of 40 nm and high scan linearity in wavenumber with Pearson's correlation coefficients r of 0.9996, consists of a supercontinuum laser, an optical band-pass filter, a linearly chirped fiber Bragg grating, an erbium-doped fiber amplifier, and two buffer stages. With sensitivity of 87 dB, high-speed OCT imaging of biological tissue in vivo is also demonstrated.

An Interface Circuit for Low-Voltage Low-Current Energy Harvesting Systems

In this paper, we present an interface circuit designed to match low-power and low-voltage harvesters to generic electronic loads. The interface circuit consists of a power management unit, a supply regulation unit, and an energy storage module. The electric power delivered by the harvester is stored in a low leakage capacitor, converted to match the load electrical characteristics, and used cyclically to supply the load during fixed time-windows. The interface circuit is compatible with dc harvesters with a current of at least 2 μA at 0.5 V and exhibits an efficiency of 65% in the 1 μW -1 mW range. The supply regulation unit is a two-stage, self-starting boost circuit that steps-up the 0.5-V input voltage to 3 V. To test the interface circuit, an autonomous wireless sensor node has been realized; it exploits the little electric power delivered by a 385 μm × 245 μm photovoltaic harvester to sense and transmit information about the environment wirelessly. The harvester is implemented with a custom 0.35-μm BCD SOI chip. The system has been designed to be low cost, fully autonomous and smaller of 9 cm 3 .

Concept of DT Fuel Cycle for a Fusion Neutron Source

A concept of DT-fusion neutron source (FNS) with the neutron yield higher than 1018 neutrons per second is under designe in Russia. Such a FNS is of interest for many applications: (i) basic and applied research (neutron scattering, etc); (ii) testing the structural materials for fusion reactors; (iii) control of sub-critical nuclear systems and (iv) nuclear waste processing (including transmutation of minor actinides). This paper describes of fuel cycle concept of a compact fusion neutron source based on a small spherical tokamak (FNS-ST) with a MW range of DT fusion power and considers the key physics issues of this device. The major and minor radii are ~0.5 and ~0.3m, magnetic field ~1.5 T, heating power less than 15MW and plasma current 1–2 MA. The system provides the fuel mixture with equal fractions of D and T (D:T = 1:1) for all FNS technology systems.

Optimizing wave energy parks with over 1000 interacting point-absorbers using an approximate analytical method

Large arrays of wave energy converters of point-absorber type are studied using an approximate analytical model. The model is validated against a numerical method that takes into account full hydrodynamic interactions based on linear potential flow theory. The low computational cost of the analytical model enables parameter studies of parks in the MW range and includes up to over 1000 interacting devices. The model is actuated by irregular wave data obtained at the Swedish west coast. In particular, focus is on comparing park geometries and improving park configurations to minimize the power fluctuations.

Changes in blood aggregation with differences in molecular weight and degree of deacetylation of chitosan

Because the molecular weight (Mw) and degree of deacetylation (DDA) of chitosan can vary depending on the purification method, the identification of appropriate chitosan structures is important for developing more effective hemostatic agents. In this study, the influence of varying Mw and DDA of chitosan on blood aggregation was characterized by 10 types of chitosan with different Mw and DDA, including oligomers. The highest aggregation of whole blood, washed erythrocytes and platelets in platelet-rich plasma (PRP) were observed in chitosan with Mw of 8.6 kDa or more and with DDA of 75 to 88%. However, chitosan with too high Mw (247 kDa) inhibited the aggregation of whole blood, washed erythrocytes and PRP at high chitosan concentration. At certain concentrations, chitosan with 75–85% DDA and 50–190 kDa and chitosan with 87.6% DDA and 247 kDa both aggregated proteins in PRP. Chitosan oligomer did not affect blood aggregation. The results suggested that the aggregation by chitosan depended on the interaction of positively charged chitosan with negatively charged erythrocytes, platelets and plasma protein. It seemed that a suitable balance of positive charge in chitosan and negative charge in hemocytes and some kinds of proteins was important. To develop a hemostatic with effective blood aggregation, the chitosan should not be limited to a single Mw and a single DDA but may be a mixed chitosan with wide range of Mw (8.6–247 kDa) and DDA of 75 to 88%.

Brightness temperatures and electron density in the solar polar coronal region on the basis of MW observations

The work is devoted to the analysis of brightness temperatures and electron densities in the solar northern polar coronal hole at distances from one to two solar radii. The observations were carried out in the MW range at the RATAN-600 telescope. It is shown that the temperature parameters for points the closest to the solar limb in the region of polar coronal hole are close to the average brightness temperatures of coronal holes observed earlier at RATAN-600 out of polar regions on the quiet Sun. The electron density distribution found along the distance in the solar polar coronal region agrees with white-light observation results.

Characterization of a variable reluctance harvester

In our last year's PowerMEMS contribution we presented a proof-of-concept of a variable reluctance harvester for the application in a railroad surveillance system. It was shown that intermittently closing a magnetic circuit could supply power output in the range of mW's. The test setup used showed unwanted energy pickup from the electro motor used. In this paper we present thorough measurements of the reluctance circuit with a compressed air motor to exclude the effects of the above mentioned magnetic stray fields. The effects of eddy currents and moment of inertia on the output power, the optimal coil position on the stators, and effects of different magnetic field strengths are studied. The gap width is set to a fixed value of 14 mm, representing a realistic scenario.

Octave-spanning semiconductor laser

We present here a semiconductor injection laser operating in continuous wave with an emission covering more than one octave in frequency, and displaying homogeneous power distribution among the lasing modes. The gain medium is based on a heterogeneous quantum cascade structure operating in the THz range. Laser emission in continuous wave takes place from 1.64 THz to 3.35 THz with optical powers in the mW range and more than 80 modes above threshold. Free-running beatnote investigations on narrow waveguides with linewidths of 980 Hz limited by jitter indicate frequency comb operation on a spectral bandwidth as wide as 624 GHz, making such devices ideal candidates for octave-spanning semiconductor-laser-based THz frequency combs.

Effect of dry-cured ham maturation time on simulated gastrointestinal digestion: Characterization of the released peptide fraction

This study deals with the identification of the peptides released after in vitro simulated gastrointestinal digestion of dry-cured Parma hams, using a physiological digestion model in terms of number of steps and composition of digestive juices. The obtained peptide mixture was analysed by ultra-high performance liquid chromatography with single quadrupole mass spectrometer detector and liquid chromatography hyphenated with triple quadrupole mass spectrometry and LTQ-orbitrap. This approach allowed for the identification of up to 81 different peptide sequences, mainly originating not only from myofibrillar proteins but also from sarcoplasmic proteins: the MW range spans between 200 and 1700Da, with a high number of very short sequences (21 dipeptides and 12 tripeptides). Several identified released peptides are precursors of potentially bioactive sequences. The effect of the maturation time of the ham on the peptide profile obtained upon digestion was assessed: Principal Component Analysis allows for differentiating between 18months and 24months aged hams, underlying the importance of maturation on the digestibility of meat proteins and on the eventual release of bioactive sequences.

Matrix-enhanced surface-assisted laser desorption/ionization mass spectrometry (ME-SALDI-MS) for mass spectrometry imaging of small molecules.

Surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS), a parallel technique to matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), utilizes inorganic particles or porous surfaces to aid in the desorption/ionization of low-molecular-weight (MW) analytes. As a matrix-free and "soft" LDI approach, SALDI offers the benefit of reduced background noise in the low MW range, allowing for easier detection of biologically significant small MW species. Despite the inherent advantages of SALDI-MS, it has not reached comparable sensitivity levels to MALDI-MS. In relation to mass spectrometry imaging (MSI), intense efforts have been made in order to improve sensitivity and versatility of SALDI-MSI. We describe herein a detailed protocol that utilizes a hybrid LDI method, matrix-enhanced SALDI-MS (ME-SALDI MS), to detect and image low MW species in an imaging mode.

Short-term slow slip events along the Ryukyu Trench, southwestern Japan, observed by continuous GNSS

In this study, short-term slow slip events (SSEs) along the Ryukyu Trench, southwestern Japan were systematically examined using continuous global navigation satellite system (GNSS) data. In total, 130 probable and 93 possible short-term SSEs in the moment magnitude (M w ) range of 5.6 to 6.8 were identified from January 1997 to November 2013 by GNSS time series offset monitoring and elastic dislocation modeling with a rectangular fault located on the subducting Philippine Sea Plate. The detected short-term SSEs were found to have a variety of characteristic recurrence intervals, magnitudes, durations, and coincidental seismic activities. Short-term SSEs without identified low-frequency earthquakes (LFEs) and low-frequency tremors (LFTs) were found to be common along the Ryukyu Trench. The total slip distributions and SSE numbers were heterogeneous and mostly between 10 and 60 km in depth. Although shallow (depth ≤20 km) short-term SSEs have never been detected along the Nankai Trough, it was notable that such SSEs often occur on the shallow plate interface along the Ryukyu Trench. This may be related to the incomplete interplate locking estimated by various geodetic studies. A band of short-term SSEs in the 20 to 40 km depth range extends from west Shikoku through the Bungo Channel to mid-Kyushu and then fades away around the subducted Kyushu-Palau Ridge. SSEs with accompanying LFEs and LFTs were found to be limited to western Shikoku and the Bungo Channel. We found several distinctive clusters of short-term SSEs, in addition to a cluster previously identified in the Yaeyama Islands. The study also identified a cluster northeast of Kikaijima consisting of 20 repeated SSEs at depths in the vicinity of 10 km near the trench where the Amami Plateau subducts, as well as another cluster southeast of Okinawa Island consisting of 29 M w ≤ 6.0 SSEs. The results suggest that the distribution of short-term SSEs, as well as that of large earthquakes, is affected by the topography of the subducting plate.

Angiotensin I‐converting enzyme inhibitory and Ca‐binding activities of peptides prepared from tuna cooking juice and spleen proteases

SummaryTuna cooking juice is a by‐product from the tuna canning industry. In this study, tuna cooking juice was hydrolysed by proteases extracted from the spleen. Tuna cooking juice showed the highest ACE inhibitory and Ca‐binding activities after hydrolysis for 270 and 180 min, respectively. The hydrolysate was further fractionated by ultrafiltration. The permeate exhibited highest ACE inhibitory and Ca‐binding activities when passed through 1 and 5 kDa cut‐off membranes, respectively. Gel filtration chromatography was used to determine the MW of bioactive peptides that exhibited highest ACE inhibitory and Ca‐binding activities. Those peptides that exhibited highest ACE inhibitory and Ca‐binding activities were the MW range of 238–829 Da and 1355–1880 Da, respectively. These results suggest that the tuna cooking juice and the spleen protease extract are a potential source of bioactive peptides that can be utilised as bioactive ingredients in functional food and nutraceuticals.

Effect of yeast-fermented and sour-dough making processes on physicochemical characteristics of β-glucan in whole wheat/oat bread

Consumption of breads containing whole grains or functional ingredients rich in dietary fiber and β-glucans has shown a dramatic increase because of their health benefits. Since bioactivity of β-glucan has been linked with its physicochemical properties, the current study was designed to investigate the effects of straight-, sponge- and sour-dough bread making processes on physicochemical characteristics of β-glucan in whole wheat/oat bread. The presence of β-glucan-degrading enzymes in the whole wheat flour used in this study were found to depolymerize β-glucan at a rate of 0.054 min−1, causing a significant reduction in β-glucan molecular weight (Mw) during dough process. Sour- and sponge-doughs had lower rates of β-glucan depolymerization, resulting in breads with medium to high β-glucan Mw range (600–1087 kg/mol) compared to straight-dough method. Dough pH, titratable acidity and fermentation plus proofing time showed significant impacts on β-glucan Mw and viscosity, but not on solubility. Acetic and propionic acids were present in all doughs, whereas lactic acid was only found in sour-dough. Generally, sour-dough bread showed better potential over yeast-fermented breads in terms of preserving β-glucan Mw and viscosity during baking process when a blend of whole wheat flour and oat bran was used.

An Autonomous Piezoelectric Energy Harvesting IC Based on a Synchronous Multi-Shot Technique

This paper presents a fully autonomous integrated circuit (IC) dedicated to piezoelectric harvesters. The novel Multi-Shot Synchronous Electric Charge Extraction (MS-SECE) performed by the IC optimizes the energy transfer from a highly charged piezoelectric harvester to a low voltage storage element. The system deals with piezoelectric powers in the 10 µW to 1 mW range and handles very high piezoelectric voltage values ( $>$ 100 V) thanks to the off-chip components around the IC. The IC has been fabricated in AMS 0.35 µm 3.3 V technology and its low power consumption (1 µW @ 5 Hz) is particularly suitable for low frequency harvesters. MS-SECE increases the extracted power compared to the Maximum Power Point Tracking (MPPT) technique but it also improves the efficiency by up to 25% compared to standard SECE. Furthermore, MS-SECE allows the use of small off-chip components: an efficiency of 61% has been reached with a 125 mm 3 coupled-inductor. Finally, the proposed power management circuit self-starts, works without any battery and its overall volume is expected to be less than 1 cm 3 .

Segmentation of the Sumatran fault

AbstractSegmentation of the Sumatran fault is discerned using an analytical approach in which a k‐means algorithm partitions earthquakes into clusters of seismicity along the fault. Clusters are tessellated into segment zones from which segment lengths and maximum credible magnitude are estimated. Decreasing the depth of seismicity sampled from 70 to 60 to 50 km reduces interaction with deeper seismicity, and results from the k‐means algorithm initially suggest that the fault has K = 14, 16, and 16 clusters, respectively. After inspection, it becomes clear that the optimum number of clusters is 16. The 16 cluster model developed into zones generates segment lengths ranging from 22 to 196 km and maximum earthquake potentials in the range of Mw 6.5–7.8. The Sumatran fault is dominated by eight great central segments distributed approximately symmetrically about Lake Maninjau. These central fault segments dominate the hazard, which is less in the far north because segments are shorter.