Horizontal Shaking Research Articles

Severe Isolated Bilateral Posterior Semicircular Canal Hypofunction inducing Perverted Head Shaking Downbeat Nystagmus

Downbeat nystagmus evoked by horizontal head shaking is most often a sign of central vestibular pathology. Rarely, however, such a sign may be present in peripheral pathologies that are well recognized clinically and semeiologically. Isolated hypofunction of the two posterior semicircular canals is also a very rarely described condition, often idiopathic or mainly due to deficiency, traumatic, autoimmune or ototoxic disorders. A 77-year-old man presented to our observation with a history of severe unsteadiness. The clinical and instrumental examination showed a downbeat nystagmus elicited by a horizontal head shaking test (perverted) and an impairment of both posterior semicircular canals. Findings suggesting other peripheral vestibular pathologies responsible for this sign or even a central vestibular lesion were absent. Clinical evaluation and blood testing ruled out the conditions reported as potentially responsible for bilateral posterior canal hypofunction. The case described should lead us to consider isolated idiopathic hypofunction of both posterior semicircular canals associated only with the nystagmus finding of a head shaking downbeat nystagmus, among the peripheral vestibular pathologies already described in the literature that could be responsible for perverted Head Shaking Down Beat Nystagmus (p-HSDBN). Therefore, when faced with the latter finding in a non-emergent outpatient setting, among the various etiopathogenetic hypotheses, this type of peripheral cause should be carefully excluded before sending patients for more invasive and costly tests that may be useless and may delay healing and recovery. The aim of our study is to present the unique case of a patient with downbeat nystagmus elicited by a horizontal head shaking test (perverted) due to an impairment of both posterior.

IMPACT OF SEISMIC ZONES ON THE STRUCTURAL DESIGN OF HIGHRISE BUILDINGS FOR RECTANGULAR AND C-SECTION

Earthquakes induce vibrations in structures, causing motion in horizontal and vertical directions, with horizontal shaking being predominant. Proper consideration of lateral loads due to earthquakes is essential for designing earthquake-resistant reinforced concrete (RC) structures, especially high-rise buildings. This study analysesthe behaviour of a G+15 multi-storied RC building with a consistent story height of 3 meters, subjected to earthquake loads, using response spectrum analysis as per IS 1893 (Part-1): 2016. The seismic performance is evaluated for four seismic zones (II, III, IV, and V) using the ETABS software. Key parameters analysed include bending moment, shear force, lateral displacement, story shear, and story drift. Comparative results highlight the effects of varying seismic zone factors. The findings contribute to understanding structural behaviour under seismic conditions and optimizing designs for enhanced safety and performance in earthquake-prone regions. Keywords: Earthquake-resistant design, Seismic analysis, Response spectrum analysis, Reinforced concrete (RC) buildings, Seismic zones, ETABS, IS 1893 (Part-1): 2016.

A novel biaxial shaking table and its performance when investigating seismic actions

AbstractThe design of a new type of biaxial shaking table is presented. The shaking table is able to apply horizontal and vertical movements to models using two actuators. It is novel in that the two actuators are horizontally aligned, through its use of a scissor mechanism, and because of its compact design which permits simple anchorage to a laboratory strong floor. The scissor mechanism translates the movement of one of the actuators to a purely vertical movement at the table. The other actuator, which moves horizontally the scissor mechanism and its supports, causes the horizontal movement of the table. The horizontal and vertical movements are applied and controlled independently, individually or simultaneously. The capability of the shaking table to control and replicate a variety of uniaxial and biaxial movements is verified by conducting several shaking table experiments. This is done when the table is naked and when it supports a payload having a nonlinear dynamic response. Very good agreements between achieved and desired uniaxial and biaxial movements are attained. Rigidity of the scissor arm mechanism and connections, and preloaded roller bearings and rail blocks, are central to its success. Displacement errors, rolling, pitching and yawing of the table's top plate are negligible. The new table type is slightly more expensive than a uniaxial system, and substantially less expensive than a six degrees‐of freedom system, meaning biaxial vertical and horizontal shaking capability can now be achieved in a laboratory at reasonable cost.

Simultaneous determination of picroside I and picroside II in dietary supplements by high performance liquid chromatography with PDA detector

Picroside I and picroside II are two compounds found in the Picrorhiza Kurroa plant, which have anti-cirrhosis, antioxidant, anti-inflammatory, fever, and asthma effects, etc. They are included in the ingredients of many dietary supplement products that help protect the liver and bile, prevent oxidation, etc. Therefore, determining the content of these two active ingredients in dietary supplements is necessary to evaluate product quality. In this study, highperformance liquid chromatography (HPLC-PDA) was used to simultaneously determine picroside I and picroside II in dietary supplements. The analytes in the samples were extracted with methanol for 60 min using a horizontal shaking technique. The extract was then filtered and determined by the HPLC–PDA method with the following conditions: C18 Column (250 mm x 4.6 mm; 5 µm) and a corresponding pre-column (3.9 mm x 5 mm; 5 µm), the mobile phase consists of a solvent mixture of acetonitrile and water according to the gradient program, detection wavelength 265 nm. The method has good specificity, the calibration curve of picroside I and picroside II has a linear coefficient R2 > 0.9999 and the repeatability and recovery meet the AOAC requirements. The method limits of detection (MDL) for these two substances were 4.3 mg/kg and 3.2 mg/kg, respectively. The method was applied to simultaneously determine picroside I and picroside II in 30 different dietary supplement products. The results detected analytes in 3 samples positive with picroside I and picroside II concentrations ranging from 98.8 to 148 mg/kg.

Precaudal Vertebrae in the Postcranial Region of Moray Eels Form Ventral Processes.

Fish vertebrae are primarily morphologically classified into precaudal vertebrae jointed to the ribs and caudal vertebrae with hemal spines, through which the caudal artery and veins pass. Moray eels (family Muraenidae) capture prey by directly biting, combining oral and pharyngeal jaw. During feeding motions, they exhibit various head manipulations, such as neurocranial elevation, ventral flexion, and horizontal shaking, with their postcranial region acting like the neck of amniotes. However, the bone morphology supporting these movements remains unclear. In this study, the vertebral morphologies of the Kidako moray (Gymnothorax kidako), starry moray (Echidna nebulosa), pink-lipped moray (Echidna rhodochilus), tidepool snake moray (Uropterygius micropterus), and Seychelles moray (Anarchias seychellensis) were investigated using X-ray computed tomography. These five species exhibited longitudinal ventral processes in the second to approximately 12th precaudal vertebrae with canals for blood vessels, structurally similar to hemal spines. In addition, the morphology of the precaudal vertebrae in three Anguilliformes species closely related to moray eels and two Gasterosteiformes species, including a seahorse that flexes its head ventrally as a feeding motion, was compared with that of moray eels. However, no remarkable ventral processes were observed in their precaudal vertebrae in the postcranial region, suggesting that these structural features in the postcranial vertebrae were preserved in Muraenidae but not necessarily required for the fish to bend its head ventrally. Although the functional significance of the ventral process has yet to be determined, our findings highlight a novel aspect of fish vertebral morphology.

Evaluation of iron speciation reference materials by wavelength-dispersive X-ray fluorescence, inductively coupled plasma optical emission spectroscopy, and flame/graphite furnace atomic absorption spectrometry for palaeoredox analysis

Fe speciation is crucial for distinguishing various redox conditions and thus offers valuable insights into the evolution of life and the environment throughout geological history. Monitoring experimental processes using reference materials is essential to ensure the consistency and reliability of Fe speciation analyses across laboratories. In this study, we evaluate the extraction processes and analytical methods used in the analysis of Fe speciation in four marine shale reference materials (WHIT, KL133, KL134, and BHW). A simple and feasible extraction process to extract Fecarb, Feox, and Femag that enables the simultaneous horizontal shaking of multiple samples by securing centrifuge tubes in foam racks is evaluated. Additionally, we compare the effects of the heating method on the extraction of FeR by heating the solution with a boiling water bath and a Bunsen burner. A new droplet method is devised for the instrumental analysis of Fe speciation using samples with high concentrations of total dissolved solids and organic matter matrices using wavelength-dispersive X-ray fluorescence spectrometry. A specialized PTFE support holder is designed to dry the filter paper in situ during sample preparation. We also compare figures of merits of wavelength-dispersive X-ray fluorescence spectrometry (WD-XRF), inductively coupled plasma-optical emission spectroscopy, and flame/graphite furnace atomic absorption spectrometry, including sample preparation, accuracy, precision, method limit of quantification, and linear range. The proposed WD-XRF droplet method will greatly simplify the sample preparation process and improve the efficiency of Fe speciation analysis.

Horizontal shaking table tests on a four-story prototype structure using multi-dimensional earthquake isolation and mitigation devices

Three-dimensional isolation system (3DIS) has been increasingly applied to civil structures with small height-width ratios, but is rarely employed in the multistory and high-rise buildings due to the lack of efficient control strategy for the rocking effect. In this paper, a simplified analysis model of 3DIS was established firstly to bring insights into the coupled motion mode caused by the rocking effect, and the influence of damping ratio and height-width ratio on the modal frequency was revealed. Then, aimed at weakening rocking motion and improving the seismic isolation efficiency, a novel multi-dimensional earthquake isolation and mitigation device (MEIMD) was proposed, and both the design composition and design principle were given in detail. To validate the effectiveness of MEIMDs, a full-scale four-story frame with a height of 13.05 m and a weight of 70 tons was produced for horizontal shaking table tests. The experimental results indicated that after adopting MEIMDs, the first-order modal frequency was 1.7 Hz, with 68% decrease compared with that of the prototype structure, and the first-order modal damping ratio was above 0.23, about eight times that of the prototype structure. Moreover, the horizontal peak acceleration was significantly decreased for each floor with a maximum reduction of 49%, while the maximum horizontal displacement and rocking response were obviously lower than the limit value specified by building codes. Therefore, the MEIMDs can not only efficiently isolate the earthquake energy, but also ensure the sufficient dynamic stability of the system. This study sheds light on the real coupled horizontal-rocking response of the base isolation system with MEIMDs, and can promote the development and application of 3DIS in multistory and high-rise buildings.

Applicability of 1D site response analysis to shallow sedimentary basins: A critical evaluation through physics‐based 3D ground motion simulations

AbstractOne‐dimensional site response analysis (1D SRA) remains the standard practice in considering the effect of local soil deposits and predicting site‐specific ground motions, although its range of applicability to realistic seismic wavefields is still in question. In this 1D approach, horizontal and vertical ground shaking are assumed to be induced by vertically propagating shear and compressional waves, respectively. A recent study based on analytical two‐dimensional (2D) plane waves and simple point source earthquake simulations has shown two mechanistic limitations in this 1D modelling technique for general inclined seismic waves, that is, systematic over‐prediction of the vertical motion and wave trapping in the 1D soil column. In this article, we evaluate in detail the applicability of this 1D modelling approach to realistic three‐dimensional (3D) simulated seismic wavefields in shallow sedimentary basins. Linear‐viscoelastic 1D SRA predictions using two types of input motions that are commonly used in practice—rock outcrop and in‐column motions, are compared with the reference true site response results from 3D earthquake simulations in terms of various measures in the frequency and time domain. It is shown that the horizontal motion in the 3D seismic wavefield exhibits dominant shear wave propagation phenomenon, while the vertical motion is a combined effect of compressional and shear waves and can be over‐predicted by the 1D approach when the incident seismic waves are inclined. Direct evidence of the wave refraction process that leads to the vertical motion over‐prediction is provided. 1D SRA with in‐column inputs can yield motions that have significantly longer duration compared to the true 3D site response solution due to trapped waves, casting in doubt the frequent need for increased soil damping in existing site studies to compensate for wave attenuation due to scattering alone. Sensitivity investigation on the increase of soil profile damping by a multiplier Dmul shows Dmul values compatible with those found in the literature for both horizontal and vertical motions. It is shown that the level of Dmul optimized for a best match of the spectral acceleration is dependent on the characteristic of the input motion and a larger Dmul is typically required for the vertical component. In contrast, 1D SRA with outcrop motions predicts motions with shorter significant duration due to its inability to capture the basin‐edge generated surface waves. A suite of ground motion simulations was performed to assess the sensitivity of the observations to the basin geologic structure including the velocity gradient, rock‐basin impedance contrast and basin depth. The analysis results show that the accuracy of the simplified 1D procedure is dependent on the wavefield composition of both the input motions and the true 3D site response solution. While the horizontal motions in shallow sedimentary basins can, to the first order, be reasonably captured by the simplified 1D approach, 1D SRA for the vertical component is in general not reliable and contributions from inclined shear waves should be accounted for in site‐specific evaluation of the vertical design ground motion.

Practical considerations in liquefaction numerical simulations calibrated with historical data

The paper details some practical considerations associated with the numerical simulation of liquefaction in Wildlife site in Southern California. Two material constitutive models are implemented in the simulations: a pressure-dependent multi-yield-surface model (PDMY) and PM4Sand, both available in the OpenSees finite elements platform. Both uniaxial as well as biaxial simulations are presented in the paper. The uniaxial simulations only include the predominant horizontal shaking component while the biaxial simulations include both orthogonal horizontal shaking components. Two historical major earthquake events were simulated: the 1987 Superstition Hills and the 2010 El Mayor Cucapah earthquakes. Laboratory experimental data used for calibration of the material models was obtained from historical data published in the 1980's. This data is particularly valuable since they correspond to intact (undisturbed) samples extracted from Wildlife site about two years before occurrence of the 1987 earthquake. In all the simulations, the models were able to capture salient features of the deposit's behavior, such as the magnitude of surface accelerations, and dilative behavior of the soil. However, the excess pore water pressure rises earlier than what the site recordings indicates. This may be attributed to the fact that the constitutive models do not consider the concept of volumetric threshold shear strain below which no excess pore water pressure is generated during cyclic shear loading. It was also found that there was a significant overestimation of the excess pore pressure for the 2010 El Mayor Cucapah earthquake simulations. This may be attributed to the effect of the site shaking history which increased the site resistance to liquefaction. This added resistance was not reflected by the numerical model since it was calibrated with samples extracted about 25 years before the 2010 earthquake.

Don’t shake it! Mechanical stress testing of mRNA-lipid nanoparticles

Shaking stress studies are typically performed during formulation development to test the liability of a drug product towards interfacial stress occurring during transport, especially if a liquid formulation is desired. We evaluated various shaking procedures using a polyA-surrogate solution and verified our findings by eGFP-LNP cell-expression experiments. Shaking on an orbital shaker in vertical and horizontal orientations at increasing speeds from 300 to 600 rpm resulted in decreasing levels of encapsulated nucleic acid content, larger LNP sizes, and decreasing PDI. We report that vertical and horizontal shaking of both polyA- and eGFP-LNPs led to white deposits on the inner glass vial surface, depending on time, rpm, and temperature. Increasing the fill volume/smaller headspace (0.3 versus 0.9 mL fill) did not mitigate this phenomenon in the studied configuration, and the use of hydrophobic primary packaging even accelerated the formation of white deposits. In contrast, we demonstrated that a lyophilized polyA-LNP dosage form was less susceptible to shaking and maintained cake integrity and product properties. Multiple vortexing steps resulted in an increase in LNP size, PDI, and a decrease in encapsulated polyA content. We conclude that shaking experiments of nucleic acid-loaded LNPs in their final configuration at intended transport conditions need to be considered during technical development.

Evaluating the performance of the twin tunnel complex in soft soil subjected to horizontal ground shaking

Tunnel construction in soft soil necessitates a thorough evaluation of soil behavior, embedment depth, ground heaves, and tunnel distortions, especially in earthquake-prone areas. This study presents a numerical parametric investigation of an unconventional tunnel complex formed by combining the closely located twin tunnels. The complex is subjected to varying horizontal ground vibrations, and the influence of lining thickness, embedment depth, and interface conditions on seismic-induced thrusts, shear forces, bending moments, tunnel distortions, and ground heaves is assessed. The applicability of analytical solutions from existing literature for singular tunnels is examined through detailed analyses of different embedment ratios. The study reveals that increased tunnel flexural rigidity leads to higher seismic-induced bending moments in the tunnel complex. Comparison of full-slip and no-slip interface conditions shows that the former exhibits reduced overall tunnel distortions. Furthermore, a comparison is made with a conventional-shaped rectangular tunnel complex. The results indicate that the twin tunnel complex behaves more rigidly under a constant embedment ratio and input motion amplitude. It also results in lower ground heaves and suffers lesser induced lining forces during seismic events, making it a superior performer in comparison. Overall, this research provides valuable insights into the behavior of twin tunnel complexes in soft soil under seismic conditions, showcasing their advantages over conventional shaped tunnels in terms of tunnel distortions, ground heaves, and overall structural response.

Near‐surface three‐dimensional multicomponent source and receiver S‐wave survey in the Tannwald Basin, Germany: Acquisition and data processing

ABSTRACTShallow 3‐D reflection seismic surveys using S‐waves have rarely been carried out, even though S‐waves can provide higher resolution subsurface images than P‐waves. We conducted a 3‐D near‐surface multicomponent source and receiver survey in Quaternary sediments. We employed a small electrodynamic seismic source with a horizontal shaking unit operated in two orientations. Three‐component geophones in an orthogonal layout covering an area of 117×99 m2 were used for recording. Changes in weather and ground conditions, including freezing and thawing during acquisition, directly influenced the data quality and resulted in discernible relative time shifts in the data. Our seismic processing flow included a four‐component rotation of the data from the Cartesian acquisition geometry into the ‘natural’ coordinate frame to orient sources and receivers in radial or transverse orientation to separate different S‐wave polarizations. The rotation increased the signal strength and helped, for example, to improve the quality of the images of the basin base. The irregular offset distribution in the common midpoint gathers impedes filtering to suppress surface waves in the f–k domain. We, therefore, applied a common‐reflection surface processing flow. After regularization, we could better remove the energy of the surface waves. Both stacked 3‐D S‐wave volumes of vertical and horizontal polarizations provide images of the Quaternary overdeepened Tannwald Basin that was partly known from previous P‐ and S‐wave 2‐D surveys. Compared to a P‐wave profile adjacent to the volume, however, the S‐wave volumes provide higher resolution images of the basin base and internal structure. The basin base is well mapped in three dimensions and shows undulations that were not obvious from the P‐wave data. Comparing the S‐wave volumes of different polarizations, we find only minor differences in the stacks and interpretations.

Determination of seven Alternaria toxins in infant milk powder by solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry

婴幼儿奶粉配料中的植物油易受到链格孢霉菌污染,因而链格孢霉毒素(ATs)成为该类食品的重点检测对象。该研究建立了超高效液相色谱-串联质谱法快速检测婴幼儿奶粉中链格孢酚、链孢酚单甲醚、交链孢霉烯、细交链孢菌酮酸、腾毒素、交链孢毒素Ⅰ、细格菌素7种ATs的方法。通过参数优化确定最佳的质谱与色谱条件,选取BEH-C18色谱柱,以0.1%甲酸水溶液-乙腈为流动相,然后分别对提取条件(提取剂比例及提取方式)以及固相萃取条件(萃取小柱、洗脱液种类及体积、上样液pH)进行优化,确定使用乙腈-水(84:16, v/v)为前两次提取剂,乙腈-甲醇-水(45:10:45, v/v/v)为第三次提取剂,水平摇匀30 min为最佳提取方式,以pH 5.5的一级水复溶上样,经HLB小柱净化,10 mL甲醇洗脱,不浓缩直接过0.22 μm滤膜后直接进行色谱分离,色谱分离后以电喷雾正负离子交替多反应监测模式分析。在最佳优化分析条件下,7种ATs在0.5~200 μg/L范围内线性关系良好,判定系数(R2)>0.9903,检出限为0.15~0.64 μg/kg,定量限为0.54~2.24 μg/kg。在3个不同加标水平下,7种ATs的平均回收率为79.1%~114.3%, RSD≤8.87%。将该方法用于60份实际婴幼儿奶粉样品的测定分析,结果显示一段奶粉和二段奶粉中未发现毒素;三段奶粉中只有1份样品被检出,检出毒素为腾毒素,其含量为4.97 μg/kg。该方法准确、快速、简便、灵敏度高,重复性与稳定性良好,可用于婴幼儿奶粉7种ATs的实际测定。

Influence of vertical ground motion on the seismic response of underground structures and underground-aboveground structure systems in liquefiable ground

Vertical ground motion components are often observed during earthquakes, which could affect the seismic performance of underground structures. This study investigates the influence of vertical ground motion on the seismic response of underground structures and underground-aboveground structure systems (UASS) in liquefiable ground. Both centrifuge shaking table tests and numerical simulations are conducted. The centrifuge shaking table tests provide basic insights into the seismic response of underground structures under simultaneous horizontal and vertical shaking, and also serve to validate the numerical simulation method. Numerical simulations are conducted using solid–fluid coupled FEM with a constitutive model for soil liquefaction analysis. The analysis results show that although the influence of vertical ground motion on the shearing related motions and internal forces of underground structures is limited, its influence on the axial force of the structure is significant, especially for the center column. The inertia effect of the aboveground structure in UASS can amplify the influence of vertical ground motion via structure-soil-structure interaction. For UASS, the horizontal and vertical relative positions of the aboveground structure and the underground structure also affect the influence of vertical ground motion.

Experimental Study on Strength and Frost Return of Red Mud Unburned Brick

The comprehensive utilization of red mud had become a common problem in alumina industry. This paper presented a method for preparing red mud non burning cementitious material without frost return. The red mud from an aluminum oxide plant in Guizhou was used as the research object, and the effects of excitation time on compressive and flexural strength were investigated. The better compressive and flexural strength were obtained when the excitation time was 6h. The compressive strength were 15.62Mpa, 18.55Mpa and 15.6Mpa respectively, and the flexural strength were 2.86Mpa, 3.58Mpa and 3.54Mpa respectively when they were mainted for 7 days, 28 days and immersion for 24 hours, which met the strength requirements of MU15. The sodium in red mud was transformed into stable sodium aluminum hydroxysilicate Al3Na4(OH)(SiO4)3 phase finally, and the concentration of Na+ in the leaching solution extracted by horizontal shaking method was about 370mg/L, so it would not cause frost return to the non burning cementitious material. This study would open up a new way for the mass consumption of red mud.

Parametric assessment of pore pressure dynamics in hydrocarbon contaminated Guwahati sand using shake table test

This paper presents a series of systematic shake table investigations to study the influence of hydrocarbon compounds on the pore pressure response of silty sand. The effect of degree of contamination in terms of crude oil content, ω (0, 2, 4, 6, 8 and 10% crude oil v/w), depth of contamination by varying the contamination depth ratio (β) from 0 to 1, and shaking history were extensively evaluated. A uniaxial scaled down model was subjected to three sequential horizontal base shaking (at a defined time interval) of peak ground acceleration 0.35 g. The results revealed a substantial improvement in the liquefaction resistance of the sand with an initial increase in crude oil content up to ω = 6%. With further increase in ω, the liquefaction resistance falloff sharply, resulting into a single-peaked profile with the highest resistance observed at ω = 6%, which has been regarded as threshold point. The microstructural mechanism believed to be responsible for such a behavior has also been discussed. Coupled effect of degree of contamination and depth of contamination has also been discussed in viewpoint of zero change point where no net change in the behavior was recorded.

Hydrogel Coatings on Container Surfaces Reduce Protein Aggregation Caused by Mechanical Stress and Cavitation.

This work reports the ability of hydrogel coatings to protect therapeutic proteins from cavitation-induced aggregation caused by mechanical stress. Here, we show that polyacrylamide hydrogel coatings on container surfaces suppress mechanical shock-induced cavitation and the associated aggregation of intravenous immunoglobulin (IVIg). First, crosslinked polyacrylamide hydrogels were grown on the surfaces of borosilicate glass vials. Treatment with ultrasound showed that these hydrogel surfaces suppressed cavitation events to levels below those found for unfunctionalized borosilicate glass. Next, IVIg solutions were loaded into these vials and subjected to tumbling, horizontal shaking, and drop testing. Aggregation was quantified by bisANS fluorescence staining and particle counting by flow imaging microscopy (FIM). In all cases, the presence of polyacrylamide hydrogels on the vial surfaces reduced the amount of IVIg aggregation and the number of particulates. In addition, the polyacrylamide appeared to have a protective effect that prevented additional aggregates from forming at extended tumbling times. Finally, drop test studies showed that the polyacrylamide coatings suppressed detectable cavitation. This work reveals how even a simple hydrogel vial coating can have a profound effect on stabilizing protein therapeutics.

Coseismic vertical ground deformations vs. intensity measures: Examples from the Apennines

DInSAR data provide a powerful tool to recognize the Earth's surface where permanent deformations are concentrated and undergo the strongest ground motion during an earthquake, i.e., defining the epicentral area. We analyzed three recent seismic events in the Apennines belt in Italy related to extensional and contractional earthquakes and documented that the largest macroseismic intensity is recorded where the ground underwent the largest vertical component of motion and the stronger vertical component of the peak ground acceleration. Besides site amplification effects that may occur everywhere even outside the epicentral area, we infer that the vertical oscillations in the so-called near-field allow the horizontal shaking to be more effective, hence producing larger damage above the active crustal volume. The active volume is the one moving vertically and is contemporaneously crossed by seismic waves nucleated by the shear on the fault. The surrounding passive volume in the far field is only crossed by seismic waves. The near field areas are elliptical and cover areas of 300–600 km2 for a range of Mw 6–6.9, and they should be the areas where the highest seismic hazard must be expected. Therefore, their area is too large to be neglected for seismic hazard assessment.

Spontaneous formation of density waves in granular matter under swirling excitation

We study here the spontaneous clustering of a submonolayer of grains under horizontal circular shaking. The clustering of grains occurs when increasing the oscillation amplitude beyond a threshold. The dense area travels in a circular fashion at the driving frequency, which even exceeds the speed of driving. It turns out that the observed clustering is due to the formation of density waves. The analysis of a phenomenological model shows that the instability of the uniform density profile arises by increasing the oscillation amplitude and captures the non-monotonic dependence of the transition amplitude of the clustering on the global density of the system. Here, the key ingredient is that the velocity of individual grains increases with the local density. The interplay of the dissipative particle–particle interaction and frictional driving of the substrate results in this dependence, which is tested with discrete element method simulations.

Forced degradation of cell-based medicinal products guided by flow imaging microscopy: Explorative studies with Jurkat cells

Cell-based medicinal products (CBMPs) offer ground-breaking opportunities to treat diseases with limited or no therapeutic options. However, the intrinsic complexity of CBMPs results in great challenges with respect to analytical characterization and stability assessment. In our study, we submitted Jurkat cell suspensions to forced degradation studies mimicking conditions to which CBMPs might be exposed from procurement of cells to administration of the product. Flow imaging microscopy assisted by machine learning was applied for determination of cell viability and concentration, and quantification of debris particles. Additionally, orthogonal cell characterization techniques were used. Thawing of cells at 5 °C was detrimental to cell viability and resulted in high numbers of debris particles, in contrast to thawing at 37 °C or 20 °C which resulted in better stability. After freezing of cell suspensions at −18 °C in presence of dimethyl sulfoxide (DMSO), a DMSO concentration of 2.5% (v/v) showed low stabilizing properties, whereas 5% or 10% was protective. Horizontal shaking of cell suspensions did not affect cell viability, but led to a reduction in cell concentration. Fetal bovine serum (10% [v/v]) protected the cells during shaking. In conclusion, forced degradation studies with application of orthogonal analytical characterization methods allow for CBMP stability assessment and formulation screening.