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Geophysical and geological studies provide evidence for cyclic changes in fault‐zone pore fluid pressure that synchronize with or at least modulate slip events. A hypothesized explanation is fault valving arising from temporal changes in fault zone permeability. In our study, we investigate how the coupled dynamics of rate and state friction, along‐fault fluid flow, and permeability evolution can produce slow slip events. Permeability decreases with time, and increases with slip. Linear stability analysis shows that steady slip with constant fluid flow along the fault zone is unstable to perturbations, even for velocity‐strengthening friction with no state evolution, if the background flow is sufficiently high. We refer to this instability as the “fault valve instability.” The propagation speed of the fluid pressure and slip pulse, which scales with permeability enhancement, can be much higher than expected from linear pressure diffusion. Two‐dimensional simulations with spatially uniform properties show that the fault valve instability develops into slow slip events, in the form of aseismic slip pulses that propagate in the direction of fluid flow. We also perform earthquake sequence simulations on a megathrust fault, taking into account depth‐dependent frictional and hydrological properties. The simulations produce quasi‐periodic slow slip events from the fault valve instability below the seismogenic zone, in both velocity‐weakening and velocity‐strengthening regions, for a wide range of effective normal stresses. A separation of slow slip events from the seismogenic zone, which is observed in some subduction zones, is reproduced when assuming a fluid sink around the mantle wedge corner. Slow slip events are observed in subduction zones worldwide. Their mechanism is not well understood, but geophysical and geological research suggests a relation with recurring changes in fluid pressure within the fault zone. Here we explore the fault valve mechanism for slow slip events using mathematical and computational models that couple fluid flow through fault zones with frictional slip on faults. The fault valve mechanism (arising from cyclic changes in the permeability or resistance to fluid flow) produces pulses of high fluid pressure, accompanied by slow slip, that advance along the fault in the direction of fluid flow. We quantify the conditions under which this occurs as well as observable properties like the propagation speed and rate of occurrence of slow slip events. We also perform simulations of subduction zone slow slip events using fault zone and frictional properties that vary with depth in a realistic manner. The simulations show that the fault valve mechanism can produce slow slip events with approximately the observed rate of occurrence, while also highlighting some discrepancies with observations that must be addressed in future work. We analyze the dynamics of fault slip with fault‐zone fluid flow and fault‐parallel permeability enhancement with slip and sealing with timeFault‐valve instability produces unidirectional aseismic slip and pore pressure pulses even with velocity‐strengthening frictionSubduction zone earthquake cycle simulations show that the fault‐valve instability can produce slow slip events below the seismogenic zone We analyze the dynamics of fault slip with fault‐zone fluid flow and fault‐parallel permeability enhancement with slip and sealing with time Fault‐valve instability produces unidirectional aseismic slip and pore pressure pulses even with velocity‐strengthening friction Subduction zone earthquake cycle simulations show that the fault‐valve instability can produce slow slip events below the seismogenic zone

For the implementation of power market in China, medium- and long-term security checks are essential for bilateral transactions, of which the electricity quantity that constitutes the generation feasible region (GFR) is the target. However, uncertainties from load forecasting errors and transmission contingencies are threats to medium- and long-term electricity trading in terms of their influences on the GFR. In this paper, we present a graphic distortion pattern in a typical three- generator system using the Monte Carlo method and projection theory based on security constrained economic dispatch. The underlying potential risk to GFR from uncertainties is clearly visualized, and their impact characteristics are discussed. A case study on detailed GFR distortion was included to demonstrate the effectiveness of this visualization model. The result implies that a small uncertainty could distort the GFR to a remarkable extent and that different line-contingency precipitates disparate the GFR distortion patterns, thereby eliciting great emphasis on load forecasting and line reliability in electricity transactions.

Golgi pH homeostasis affects many different biological processes, including glycosylation. Recent studies have demonstrated that transmembrane protein 165 (TMEM165) deficiency leads to Golgi glycosylation abnormalities by disturbing Golgi pH homeostasis. However, due to the lack of specific tools to measure Golgi pH in situ, evidence for TMEM165 involvement in H+transport in the Golgi apparatus is still absent. Herein, the photoacoustic and fluorescent dual-mode probe CPH was developed for ratiometric detection of Golgi pH. CPH was proved to accumulate in the Golgi apparatus and reversibly image Golgi pH in real-time with high sensitivity in cells. Furthermore, we found that the absence of TMEM165 influenced H+equilibrium and caused Golgi apparatus acidification. Our work provides strong evidence that TMEM165 regulates Golgi pH homeostasis. Moreover, we believe that CPH has the potential to be a practical tool to monitor Golgi pH in various biological processes.

Magnesium, as a biodegradable metal, is a promising candidate for biomedical applications. To modify the degradation behavior of magnesium and improve its osteocompatibility, chemical conversion and spin coating methods were combined to develop a diammonium hydrogen phosphate-pretreated/poly(ether imide) (DAHP/PEI) co-coating system. The diammonium hydrogen phosphate pretreatment was employed to enhance the attachment between PEI coatings and the magnesium substrate; meanwhile, it could serve as another bioactive and anticorrosion layer when PEI coatings break down. Surface characterization, electrochemical tests, and short-term immersion tests in DMEM were performed to evaluate DAHP/PEI coatings. Electrochemical measurements showed that DAHP/PEI coatings significantly improved the corrosion resistance of pure magnesium. No obvious changes of the chemical compositions of DAHP/PEI coatings occurred after 72 h of immersion in DMEM. An in vitro cytocompatibility study confirmed that viability and LDH activity of human osteoblast-like cells on DAHP/PEI coatings showed higher values than those on the DAHP-pretreated layer and pure magnesium. The DAHP-pretreated layer could still enhance the ALP activity of MG-63 cells after the degradation of PEI in DAHP/PEI coatings. Besides that, the in vitro cellular response to the treated magnesium was investigated to gain knowledge on the differentiation and proliferation of human adipose-derived stem cells (hADSCs). Cell distribution and morphology were observed by fluorescence and SEM images, which demonstrated that DAHP/PEI coatings facilitated cell differentiation and proliferation. The high level of C-terminals of collagen type I production of hADSCs on DAHP/PEI coatings indicated the potential of the coating for promoting osteogenic differentiation. Positive results from long-term cytocompatibility and proliferation tests indicate that DAHP/PEI coatings can offer an excellent surface for hADSCs.

Biodegradable polymer coatings on magnesium alloys are attractive, as they can provide corrosion resistance as well as additional functions for biomedical applications, e.g., drug delivery. A gelatin nanospheres/chitosan (GNs/CTS) composite coating on WE43 substrate was fabricated by electrophoretic deposition with simvastatin (SIM) loaded into the GNs. Apart from a sustained drug release over 28 days, an anticorrosion behavior of the coated WE43 substrates was confirmed by electrochemical tests. Both the degradation and corrosion rates of the coated substrate were significantly minimized in contrast to bare WE43. The cytocompatibility of the coated samples was analyzed  both quantitatively and qualitatively. Additionally, the osteogenic differentiation of MC3T3-E1 cells on SIM-containing coatings was assessed by measuring the expression of osteogenic genes and related proteins, alkaline phosphatase (ALP) activity, and extracellular matrix mineralization, showing that the SIM-loaded composite coating could upregulate the expression of osteogenic genes and related proteins, promote ALP activity, and enhance extracellular matrix mineralization. In summary, the SIM-loaded GNs/CTS composite coatings were able to enhance the corrosion resistance of the WE43 substrate and promote osteogenic activity, thus demonstrating a promising coating system for modifying the surface of magnesium alloys targeted for orthopedic applications.

Offshore sensor networks like DONET and S‐NET, providing real‐time estimates of wave height through measurements of pressure changes along the seafloor, are revolutionizing local tsunami early warning. Data assimilation techniques, in particular, optimal interpolation (OI), provide real‐time wavefield reconstructions and forecasts. Here we explore an alternative assimilation method, the ensemble Kalman filter (EnKF), and compare it to OI. The methods are tested on a scenario tsunami in the Cascadia subduction zone, obtained from a 2‐D coupled dynamic earthquake and tsunami simulation. Data assimilation uses a 1‐D linear long‐wave model. We find that EnKF achieves more accurate and stable forecasts than OI, both at the coast and across the entire domain, especially for large station spacing. Although EnKF is more computationally expensive than OI, with development in high‐performance computing, it is a promising candidate for real‐time local tsunami early warning. Recent years have seen more research on tsunami early warning using data from seafloor pressure sensors. Forecasts of the tsunami wave height can be computed by incorporating the pressure observations into the physical model of wave propagation. The current approach uses a simple, constant linear interpolator to blend the data with the model forecast. To improve the accuracy and stability of the forecast, we propose a more mathematically sophisticated approach that dynamically updates this interpolator, as the physical model evolves and as more data become available. This will incorporate more information into the forecast and optimize it. Using a scenario tsunami from our earthquake‐tsunami coupled simulation in the Cascadia subduction zone, we run our proposed data assimilation approach. The predicted wave heights across the ocean and at the coast are more accurate and consistent over time. More reliable forecasts can therefore be issued to coastal residents earlier in the event of a destructive tsunami. Although our method takes longer to run, with greater computing power and more efficient implementation, it is a promising candidate for real‐time tsunami early warning. We propose an alternative tsunami wavefield assimilation method, the ensemble Kalman filterThe methods are tested on scenario tsunami in Cascadia from fully coupled dynamic earthquake and tsunami simulationEnsemble Kalman filter achieved more accurate and stable forecasts compared to optimal interpolation

Electrospun hybrid scaffolds are an effective platform to deliver drugs site specifically for the prevention and treatment of diseases in addition to promote tissue regeneration because of the flexibility to load drugs therein. In the present study, electrospun hybrid scaffolds containing antibiotics were developed to support cellular activities and eliminate potential postoperative inflammation and infection. As a model drug, levofloxacin (LFX) was successfully incorporated into pure polyhydroxybutyrate/poly(ε-caprolactone) (PHB/PCL) scaffolds and PHB/PCL/sol–gel-derived silica (SGS) scaffolds. The influence of LFX on the morphology, mechanical performance, chemical structure, drug release profile, and antibacterial effect of the scaffolds was thoroughly and comparatively investigated. MG-63 osteoblast-like cell cultivation on both scaffolds certified that LFX inclusion did not impair the biocompatibility. In addition to the favorable cellular proliferation and differentiation, scaffolds containing both LFX and SGS displayed highly increased mineralization content. Therefore, the present multifunctional hybrid scaffolds are promising in tissue engineering applications.

Fluids influence fault zone strength and the occurrence of earthquakes, slow slip events, and aseismic slip. We introduce an earthquake sequence model with fault zone fluid transport, accounting for elastic, viscous, and plastic porosity evolution, with permeability having a power‐law dependence on porosity. Fluids, sourced at a constant rate below the seismogenic zone, ascend along the fault. While the modeling is done for a vertical strike‐slip fault with 2D antiplane shear deformation, the general behavior and processes are anticipated to apply also to subduction zones. The model produces large earthquakes in the seismogenic zone, whose recurrence interval is controlled in part by compaction‐driven pressurization and weakening. The model also produces a complex sequence of slow slip events (SSEs) beneath the seismogenic zone. The SSEs are initiated by compaction‐driven pressurization and weakening and stalled by dilatant suctions. Modeled SSE sequences include long‐term events lasting from a few months to years and very rapid short‐term events lasting for only a few days; slip is ∼1–10 cm. Despite ∼1–10 MPa pore pressure changes, porosity and permeability changes are small and hence fluid flux is relatively constant except in the immediate vicinity of slip fronts. This contrasts with alternative fault valving models that feature much larger changes in permeability from the evolution of pore connectivity. Our model demonstrates the important role that compaction and dilatancy have on fluid pressure and fault slip, with possible relevance to slow slip events in subduction zones and elsewhere. Water in the crust plays an important role in controlling the strength of fault zones and frictional sliding, which manifest as earthquakes and slow slip events that do not produce ground shaking. In this study, we perform computer modeling of earthquake sequences that are coupled to the evolution of fluid pressure and rock properties. In particular, compaction or dilation of the water‐filled pore space in rock drives changes in fluid pressure and influences the fault's frictional resistance to slip. The model quantifies the effects of compaction and dilation on both large earthquakes and slow slip events, providing specific predictions regarding slow slip event properties, pressure changes, and changes in fluid flow that might be testable with geophysical, geologic, and geochemical data. Fluid pressure changes from pore compaction and dilatancy influence slow slip events in our modelModeled slow slip events span long‐term events lasting for months to years to rapid short‐term events for a few daysEarthquake recurrence interval is controlled in part by compaction‐driven pressurization and weakening Fluid pressure changes from pore compaction and dilatancy influence slow slip events in our model Modeled slow slip events span long‐term events lasting for months to years to rapid short‐term events for a few days Earthquake recurrence interval is controlled in part by compaction‐driven pressurization and weakening

Fe-based materials are of interest for use in biodegradable implants. However, their corrosion rate in the biological environment may be too slow for the targeted applications. In this work, sandblasting is applied as a successful surface treatment for increasing the degradation rate of pure iron in simulated body fluid. Two sandblasting surfaces with different roughness present various surface morphologies but similar degradation products. Electrochemistry tests revealed that sandblasted samples have a higher corrosion rate compared to that of bare iron, and even more noteworthy, the degradation rate of sandblasted samples remains significantly higher during long-term immersion tests. On the basis of our experimental results, the most plausible reasons behind the fast degradation rate are the special properties of sandblasted surfaces, including the change of surface composition (for the early stage), high roughness (occluded surface sites), and high density of dislocations. Furthermore, the cytocompatibility was studied on sandblasting surfaces using human osteoblast-like cells (MG-63) by indirect and direct contact methods. Results revealed that sandblasting treatment brings no adverse effect to the growth of MG-63 cells. This work demonstrates the significant potential of sandblasting for controlling the degradation behavior of iron-based materials for biomedical applications.

Inversions of InSAR ground deformation in the Delaware Basin have revealed an aseismic slip on semi‐optimally oriented normal faults located close to disposal wells. The slip, occurring over 3–5 years, extends approximately 1 km down‐dip, over 10 km along strike, and reaches 25 cm. We develop and calibrate 2D and pseudo‐3D coupled pore pressure diffusion and rate‐state models with velocity‐strengthening friction tailored to this unique height‐bounded fault geometry. Pressure diffusion is limited to a high‐permeability fault damage zone, and the net influx of fluid is adjusted to match the observed slip. A 1–2 MPa pressure increase initiates slip, with ∼5 MPa additional pressure increase required to produce ∼20 cm slip. Most slip occurs at approximately constant friction. Fault zone permeability must exceed ∼10−13m2to match the along‐strike extent of slip. Models of the type developed here can be used to operationally manage injection‐induced aseismic slip. Disposal of wastewater through wells in the Delaware Basin is causing slip on shallow faults. This slip occurs gradually over several years. We develop computer simulations of fluid transport along these faults, calculating pressure changes in the fluid that weaken the fault and cause it to slip. We adjust properties of the fault zone and the rate at which fluid enters the fault zone to achieve consistency with satellite‐based measurements of the amount and spatial extent of slip. Once calibrated, these models can be used to predict the slip response to hypothetical injection scenarios. We model the aseismic slip response to injection‐induced fluid infiltration and pressurization of the fault damage zoneMatching the observed slip requires a 5 MPa pressure increase beyond the 1–2 MPa required to initiate slipMatching observed along‐strike extent of slip requires fault zone permeability of 10–13 m2or greater We model the aseismic slip response to injection‐induced fluid infiltration and pressurization of the fault damage zone Matching the observed slip requires a 5 MPa pressure increase beyond the 1–2 MPa required to initiate slip Matching observed along‐strike extent of slip requires fault zone permeability of 10–13 m2or greater

It is sometimes necessary to perform two-level factorial designs in blocks of size two. We investigate what combinations of designs in different pairing arrangements permit estimation of all main effects and two-factor interactions. The confounding patterns of selected combination designs which combine several 2kdesigns in different pairings are presented for k= 2, 3, 4, and 5. We seek “best” combination designs which provide the most pure (within block) estimates of main effects and two-factor interactions under each confounding pattern given. Some “best” sequential combinations of 2kdesigns with various choices of initial arrangements are also given. The popular mirror-image pairing design is not the best initial arrangement, but is valuable for providing pure estimates of all the main effects. Extensions to 2k−pfractional factorial designs are illustrated. An example illustrates the use of a follow-up inter-block analysis.

It is widely recognized that fluid injection can trigger aseismic fault slip. However, the processes by which the fluid‐rock interactions facilitate or inhibit slip are poorly understood and some are oversimplified in most models of injection‐induced slip. In this study, we perform a 2D anti‐plane shear investigation of aseismic slip that occurs in response to fluid injection into a permeable fault governed by rate‐and‐state friction. We account for porosity and permeability changes that accompany slip, including dilatancy, and quantify how these processes affect pore pressure diffusion, which couples to aseismic slip. Fault response to injection has two phases. In the first phase, slip is negligible and pore pressure closely follows the standard linear diffusion model. Pressurization eventually triggers aseismic slip close to the injection site. In the second phase, aseismic slip front expands outward and dilatancy causes pore pressure to depart from the linear diffusion model. We quantify how prestress, injection rate, permeability and other fluid transport properties affect the slip front migration rate, finding rates ranging from 10 to 1,000 m/day for typical parameters. The migration rate is strongly influenced by the fault's closeness to failure and injection rate. The total slip on the fault, on the other hand, is primarily determined by the injected volume, with minimal sensitivity to injection rate. Additionally, we show that when dilatancy is neglected, slip front migration rate and total slip can be several times higher. Our modeling demonstrates that porosity and permeability evolution, especially dilatancy, fundamentally alters how faults respond to fluid injection. The underground injection of fluids during wastewater disposal, geothermal operations, and other energy‐production activities has been linked to the occurrence of earthquakes. In addition to earthquakes, fluid injection can also trigger aseismic slip on faults, that is, frictional sliding that occurs so slowly that seismic waves and ground shaking are not produced. Here, we perform computer modeling of fluid injection and aseismic slip, exploring how the injection rate and fluid transport properties influence the aseismic slip response. We speculate that additional complexity in frictional properties and other conditions would cause aseismic slip to be accompanied by numerous, small earthquakes (microseismicity), as is often observed during injection. We quantify the rate at which aseismic slip migrates outward from the injection site and compare predicted migration rates to observed microseismicity patterns. Our model also predicts fluid pressure changes, slip, rock deformation surrounding the fault, and fluid flow paths that might be measurable and used to validate the modeling. Modeling of constant rate fluid injection into a fault predicts steadily propagating aseismic slip frontMigration rate of aseismic slip front increases with injection rate and ranges from 10 to 1,000 m/day for typical parametersDilatancy and permeability enhancement alter system response as compared to linear pore pressure diffusion Modeling of constant rate fluid injection into a fault predicts steadily propagating aseismic slip front Migration rate of aseismic slip front increases with injection rate and ranges from 10 to 1,000 m/day for typical parameters Dilatancy and permeability enhancement alter system response as compared to linear pore pressure diffusion