Finger Structure Research Articles

EGR1 Promotes Erastin-induced Ferroptosis Through Activating Nrf2-HMOX1 Signaling Pathway in Breast Cancer Cells.

Purpose: Early growth response 1 (EGR1) is a crucial transcription factor composed of zinc finger structures, inhibitory and activating regulatory regions. We identified the biological effect and molecular mechanisms of EGR1 in breast cancer (BC). Methods: We used qRT-PCR, western blot and immunohistochemistry to examine the expression of EGR1 in BC samples. CCK-8 and colony assay were performed to reveal the effect of EGR1 on the proliferation of BC cells. LDH release assay, MCB assay, MDA assay, C-AM assay and TMRE assay were performed to measure the levels of LDH release, GSH, MDA, LIP and mitochondrial membrane potential. The regulation of EGR1 on the expression of Nrf2 and HMOX1 was investigated through Western blot. Xenograft models were conducted to determine the impact of EGR1 overexpression on BC in vivo. Results: The expression of EGR1 was downregulated in BC tissues compared with the normal tissues, and lower expression of EGR1 associated with poorer clinical outcome in BC patients. Through in vitro experiments, we found that EGR1 downregulation facilitated the proliferation of BC cells, and overexpression of EGR1 inhibited the proliferation of BC cells. In addition, EGR1 knockdown alleviated erastin-induced ferroptosis and overexpression of EGR1 facilitated erastin-induced ferroptosis in BC cells. Moreover, overexpression of EGR1 facilitated the anti-tumor effect caused by erastin in vivo. Mechanistically, the phosphorylation levels of Nrf2 and the expression of HMOX1 were reduced due to the downregulation of EGR1, and increased due to the upregulation of EGR1. Additionally, the finding that EGR1 facilitated erastin-induced ferroptosis was alleviated by the inhibition of Nrf2-HMOX1. Conclusion: The expression of EGR1 is downregulated in BC, which is correlated with poor prognosis of BC patients. EGR1 suppresses the proliferation of BC cells and facilitates erastin-induced ferroptosis by activating Nrf2-HMOX1 signaling pathway in BC cells.

A Simplified Inchworm Rotary Piezoelectric Actuator Inspired by Finger Twist: Design, Modeling, and Experimental Evaluation

Inchworm rotary piezoelectric actuators (PAs) have been widely utilized in the ultraprecision rotary positioning mechanisms because of their high precision and theoretical no backward motions. Existing inchworm rotary PAs are still bothered with the complicated structures driven by at least three piezoelectric stacks (PSAs) and relatively low speed. In this study, inspired by the finger structure, we present a simplified inchworm rotary PA driven by only two PSAs. The human finger twist motion is firstly imitated and utilized to increase the rotation from one to four times in one cycle, which improves the output speed and no backward motion can be observed in the rotation curves. Under a voltage of 150 V and a frequency of 20 Hz, the actuator achieved a maximum rotation speed of 0.16 rad/s, a carrying load of 0.5 kg and an output torque of 0.05 N·m. Furthermore, this actuator achieved a high step repeatability in the large scale of 360°, whose maximum deviation is less than 0.8 mrad.

Immiscible Viscous Fingering: The Effects of Wettability/Capillarity and Scaling

AbstractRealistic immiscible viscous fingering, showing all of the complex finger structure observed in experiments, has proven to be very difficult to model using direct numerical simulation based on the two-phase flow equations in porous media. Recently, a method was proposed by the authors to solve the viscous-dominated immiscible fingering problem numerically. This method gave realistic complex immiscible fingering patterns and showed very good agreement with a set of viscous unstable 2D water → oil displacement experiments. In addition, the method also gave a very good prediction of the response of the system to tertiary polymer injection. In this paper, we extend our previous work by considering the effect of wettability/capillarity on immiscible viscous fingering, e.g. in a water → oil displacements where viscosity ratio $$\left( {\mu_{{\text{o}}} /\mu_{{\text{w}}} } \right) \gg 1$$ μ o / μ w ≫ 1 . We identify particular wetting states with the form of the corresponding capillary pressure used to simulate that system. It has long been known that the broad effect of capillarity is to act like a nonlinear diffusion term in the two-phase flow equations, denoted here as $$D(S_{w} )$$ D ( S w ) . Therefore, the addition of capillary pressure, $$P_{c} (S_{w} )$$ P c ( S w ) , into the equations acts as a damping or stabilisation term on viscous fingering, where it is the derivative of this quantity that is important, i.e. $$D(S_{w} )\sim\left( {dP_{c} (S_{w} )/dS_{w} } \right)$$ D ( S w ) ∼ d P c ( S w ) / d S w . If this capillary effect is sufficiently large, then we expect that the viscous fingering to be completely damped, and linear stability theory has supported this view. However, no convincing numerical simulations have been presented showing this effect clearly for systems of different wettability, due to the problem of simulating realistic immiscible fingering in the first place (i.e. for the viscous-dominated case where $$P_{c} = 0$$ P c = 0 ). Since we already have a good method for numerically generating complex realistic immiscible fingering for the $$P_{c} = 0$$ P c = 0 case, we are able for the first time to present a study examining both the viscous-dominated limit and the gradual change in the viscous/capillary force balance. This force balance also depends on the physical size of the system as well as on the length scale of the capillary damping. To address these issues, scaling theory is applied, using the classical approach of Rapport (1955), to study this scaling in a systematic manner. In this paper, we show that the effect of wettability/capillarity on immiscible viscous fingering is somewhat more complex and interesting than the (broadly correct) qualitative description above. From a “lab-scale” base case 2D water → oil displacement showing clear immiscible viscous fingering which we have already matched very well using our numerical method, we examine the effects of introducing either a water wet (WW) or an oil wet (OW) capillary pressure, of different “magnitudes”. The characteristics of these two cases (WW and OW) are important in how the value of corresponding $$D(S_{w} )$$ D ( S w ) functions, relate to the (Buckley–Leverett) shock front saturation, $$S_{wf}$$ S wf , of the viscous-dominated ($$P_{c} = 0$$ P c = 0 ) case. By analysing this, and carrying out some confirming calculations, we show clearly why we expect to see much clearer immiscible fingering at the lab scale in oil wet rather than in water wet systems. Indeed, we demonstrate why it is very difficult to see immiscible fingering in WW lab systems. From this finding, one might conclude that since no fingering is observed for the WW lab-scale case, then none would be expected at the larger “field” scale. However, by invoking scaling theory—specifically the viscous/capillary scaling group, $$C_{{{\text{VC1}}}}$$ C VC1 , (and a corresponding “shape group”, $$C_{{{\text{S}}1}}$$ C S 1 ), we demonstrate very clearly that, although the WW viscous fingers do not usually appear at the lab scale, they emerge very distinctly as we “inflate” the system in size in a systematic manner. In contrast, we demonstrate exactly why it is much more likely to observe viscous fingering for the OW (or weakly wetting) case at the lab scale. Finally, to confirm our analysis of the WW and OW immiscible fingering conclusions at the lab scale, we present two experiments in a lab-scale bead pack where $$\left( {\mu_{{\text{o}}} /\mu_{{\text{w}}} } \right) = 100$$ μ o / μ w = 100 ; no fingering is seen in the WW case, whereas clear developed immiscible fingering is observed in the OW case.

Designed Structures of Interdigital Electrodes for Thin Film SAW Devices.

This paper studied the impact of the microstructure of interdigital electrodes on the performance of surface acoustic wave (SAW) resonators and proposed an innovative piston, dummy finger and tilt (PDT) structure, which was then applied to the GLONASS L3 band filters. Through the adoption of 3D finite element simulation (FEM), photolithography, and testing on an incredible high-performance surface acoustic wave (I.H.P. SAW) substrate, it is concluded that the total aperture length is 20T (T is period), resulting in a more optimal resonator performance; changing the width and length of the piston can suppress transverse modes spurious, but it does not enhance impedance ratio; to further improve the quality of the SAW resonator, the proposed PDT structure has been experimentally proven to not only effectively suppress transverse modes spurious but also possess a high impedance ratio. By utilizing a PDT structure within a "T + π" topology circuit, we successfully designed and manufactured a GLONASS L3 band filter with a bandwidth of 8 MHz and an insertion loss of 3.73 dB. The design of these resonators and filters can be applied to the construction of SAW filters in similar frequency bands such as BeiDou B2 band or GPS L2/L5 band.

Evolution of the Tóxicos en Levadura 63 (TL63) gene family in plants and functional characterization of Arabidopsis thaliana TL63 under oxidative stress.

TL63 orthologs were angiosperm specific and had undergone motifs loss and gain, and increased purifying selection. AtTL63 was involved in the response of yeast and Arabidopsis plants to oxidative stress. The Tóxicos en Levadura (TL) family, a class of E3 ubiquitin ligases with typical RING-H2 type zinc finger structure, plays a pivotal role in mediating physiological processes and responding to stress in plants. However, the evolution and function of TL63 remain unclear. In this study, TL63 homologs were dated roughly back to the origin of land plants and confirmed to have subjected to the gain and loss of motifs and increased purifying selection. Phylogenetic analysis displayed that 279 TL63s could be divided into four main clades (Clade A-D). Notably, the ancestral tandem TL40/41 cluster contributed to the expansion of modern Brassicaceae TL40/41. The substitution rate tests revealed that the TL63 lineage was evidently different from other lineages. The codon usage index exhibited that monocotyledons preferred to use not A3s and T3s, but C3s, G3s, CAI, CBI and Fop. Sequence analysis showed that the TL63 homologs had conserved TM and GLD motifs and RING-H2 domain whose key amino acid residues accounted for the high average abundance. Particularly, Arabidopsis thaliana TL63 (AtTL63) was located in the nuclei, cell membranes and peroxisomes and expressed universally and significantly throughout A. thaliana development. Under H2O2 treatment, low or moderate expression of the AtTL63 held beneficial effects on the growth and viability of yeast cells and the mutation or overexpression of the AtTL63 positively affected the growth of A. thaliana plants. In brief, this study could supply useful insight into the evolution of the plant TL63s and the AtTL63 functions under oxidative stress.

Arsenite Impairs BRCA1-Dependent DNA Double-Strand Break Repair, a Mechanism Potentially Contributing to Genomic Instability.

BRCA1 is a key player in maintaining genomic integrity with multiple functions in DNA damage response (DDR) mechanisms. Due to its thiol-rich zinc-complexing domain, the protein may also be a potential target for redox-active and/or thiol-reactive (semi)metal compounds. The latter includes trivalent inorganic arsenic, which is indirectly genotoxic via induction of oxidative stress and inhibition of DNA repair pathways. In the present study, we investigated the effect of NaAsO2 on the transcriptional and functional DDR. Particular attention was paid to the potential impairment of BRCA1-mediated DDR mechanisms by arsenite by comparing BRCA1-deficient and -proficient cells. At the transcriptional level, arsenite itself activated several DDR mechanisms, including a pronounced oxidative stress and DNA damage response, mostly independent of BRCA1 status. However, at the functional level, a clear BRCA1 dependency was observed in both cell cycle regulation and cell death mechanisms after arsenite exposure. Furthermore, in the absence of arsenite, the lack of functional BRCA1 impaired the largely error-free homologous recombination (HR), leading to a shift towards the error-prone non-homologous end-joining (NHEJ). Arsenic treatment also induced this shift in BRCA1-proficient cells, indicating BRCA1 inactivation. Although BRCA1 bound to DNA DSBs induced via ionizing radiation, its dissociation was impaired, similarly to the downstream proteins RAD51 and RAD54. A shift from HR to NHEJ by arsenite was further supported by corresponding reporter gene assays. Taken together, arsenite appears to negatively affect HR via functional inactivation of BRCA1, possibly by interacting with its RING finger structure, which may compromise genomic stability.

Corresponding measurement-based patternmaking method for customized gloves to support smart wearables

This study developed a corresponding measurement-based patternmaking (CMP) method for customized gloves applicable to different hand shapes to support the manufacturing of smart wearables. This method can be used directly to implement a 2D block pattern of gloves by hand measuring and 3D scanning alone. Our customized glove prototype was manufactured considering the glove’s functionality and usability and in accordance with the protocol designed, targeting individual participants. The CMP method for customized gloves was verified by checking the function and functional fit of the customized glove prototype through a wear test that compared the prototype with a commercial glove. In the process, the rules of the existing CMP method for customized leggings were adjusted for the protocol to comply with the structural specificity of the hand. Accordingly, a guideline for customized gloves’ patternmaking was proposed to help future developers. The originality of the CMP method lies in the pattern construction of a perfectly matched size, a side panel structure of C-curve fingers, and patterns for a trapezoid hand proximal part structure. Furthermore, the newly devised CMP method for customized gloves can be used as a baseline for smart wearable devices to offer high functionality and usability for individuals with unique hand shapes who need customized gloves.

Design, Modeling and Experiments of a Variable Stiffness Soft Robotic Glove for Stroke Patients With Clenched Fist Deformity

Soft wearable devices for hand rehabilitation can assist activities of daily living. While existing soft robotic gloves can help with finger flexion, they are less suitable for patients who cannot extend their fingers due to poststroke increased muscular tension. In this letter, we proposed a variable stiffness pneumatic actuator that effectively increases the elasticity of the actuator to facilitate finger extension. The actuator consists of a fiber-reinforced actuator and a multi-stage articulated elastomer. It bends and extends by pneumatic actuation, with multi-stage articulated elastomer providing stiffness adjustment to accommodate varying joint resistance. The variable stiffness mechanism was achieved by the multi layered discrete metal plates which can gracefully fit the unique structure of human fingers. Analysis models were established to quantify the actuator's air pressure, vacuum pressure, and bending angle, also to predict the actuator's stiffness under different vacuum pressures. Experiments and finite element simulation were carried out to evaluate the bending performance of the actuator. Meanwhile, the output force and variable stiffness characteristic of the actuator were tested. The results show that the actuator can achieve 1.54 N fingertip output force and 2.4 times stiffness change, which satisfy the requirement of stroke patient. In addition, a clenched artificial hand with similar damper forces to human hand was applied to further verify the extending effect of the variable stiffness actuator. Finally, a rehabilitation glove integrated with multiple actuators was tested to assess typical rehabilitation gestures and the ability to grasp daily objects.

Structural design and analytical study of a new polysilicon tunable microactuator for measurement of different resonance frequencies

This paper presents a novel MEMS tunable resonator that draws inspiration from the folded beam structure in its comb drive resonator design. Conventional electrostatic comb-drive resonators commonly employ folded-beam suspensions to achieve linearity and reduce system stiffness. The proposed design incorporates eight zigzag-shaped meander springs to support the comb finger structure, featuring two central anchors. The objective of this design is to introduce zigzag-shaped nested-folded beam suspensions to the comb parts, thereby reducing the tuning voltage and sensor size. The governing equations are provided to calculate the support springs’ stiffness, and a comparative analysis is conducted to evaluate the stiffness of the proposed design against other parameters. The mathematical analysis demonstrates that Zigzag Nested-Folded beams result in a decreased resonance frequency and a softened electrostatic spring under applied DC voltage. The integration of zigzag-shaped nested-folded beam flexures enables MEMS resonator devices to exhibit reduced stiffness, leading to a lower pull-in voltage. The resonator design and simulation are performed using Intellisuite and SolidWorks software. Results indicate that the resonant frequency of the proposed tunable comb-drive resonator, equipped with 26 finger pairs and a movable part displacement of 21 μm, is reduced by 66% from the original frequency of 2.420 kHz when a tuning voltage of 59 V is applied. Simultaneously, the corresponding effective stiffness decreases by 66% from the initial value of 0.72 N m−1. This compact resonator occupies an area of approximately 1.058×278 (μm)2, demonstrating a smaller size compared to previous works.

Krüppel-homologue 1 regulates the development of Tuta absoluta and its cascade regulation pattern in the juvenile hormone signalling pathway.

Tomato leaf miner, Tuta absoluta (Meyrick), is one of the most destructive quarantine pests globally. It has been confirmed that Krüppel-homologue 1 (kr-h1) plays a key role in the regulation of juvenile hormone (JH). However, it is unclear how kr-h1 regulates the synthesis of JH and its cascade regulation pattern in tomato leaf miner. Here, we obtained the six JH signalling genes (kr-h1, Methoprene-tolerant, Forkhead box O, Juvenile acid methyltransferase, Juvenile hormone esterase and Fatty acid synthase 2), and applied RNA interference to explore the role of kr-h1 and the seven genes (plus Vitellogenin) regulation relationship in T. absoluta. Bioinformatics analysis revealed the structural characteristics of kr-h1 protein and JH receptor Met, which contained eight C2H2 zinc finger structures and three typical domains of the bHLH-PAS family, respectively. The expression levels of Met and Vg were upregulated after RNAi of kr-h1 gene, while the gene levels of JHAMT and FAS2 were downregulated. Furthermore, topical application of JH analogue to second instar larvae could induce the expression of kr-h1 and inhibit the expression of Met. Our study reveals the mechanism by which kr-h1 regulates JH pathway genes, which could be applied to control the growth of tomato leaf miners.

Screen-printed water-based conductive ink on stretchable fabric for wearable micro-supercapacitor

Micro-supercapacitors (MSCs) have received a lot of attention with the rapid development of wearable, highly integrated, and flexible electronics due to their high power density and long cycle life. Among the preparation methods, screen printing is widely used due to its simplicity, low cost, integratability, and ease of industrial production. However, the conductivity, rheology, and printability of the ink are still required to be further optimized in order to improve the resolution and electrochemical properties of the printed patterns. And combining a high energy capacity and wearability of MSCs is also a big challenge. Therefore, a green and environmentally friendly water-based conductive ink is prepared herein to develop a CO-CNT-MnO2-based micro-electrode on stretchable cotton/spandex fabric by screen printing. The CO-CNT-MnO2/F-based MSCs with a forked finger structure are further assembled combined with PVA/LiCl, and high electrochemical performance of the assembled device due to the synergy of double layer capacitance and pseudocapacitor capacitance storage could be achieved as an area capacitance of 8.479 mF/cm2 at 10 mV/s and reach maximum energy density of 0.132 mWh/cm2 at power density of 0.176 mW/cm2. In addition, the assembled MSCs still have high capacitance retention under stretching/folding/bending/friction conditions. This work highlights the great potential of the new water-based conductive ink for the application of stretchable MSCs based on screen printing.

Highly Sensitive Ultraviolet Photodetector Based on an AlGaN/GaN HEMT with Graphene‐On‐p‐GaN Mesa Structure

AbstractThe advantageous role of 2D electron gas presence at the AlGaN/GaN interface attracts huge interest in the field of GaN‐based ultraviolet photodetector technology. However, the presence of high dark current deteriorates the photodetector performance by diminishing several figures of merit. In this work, enhanced figures of merit are demonstrated by employing interdigitated p‐GaN finger structure on the top of the AlGaN/GaN heterostructure. The commonly present high dark current in p‐GaN/AlGaN/GaN planar photodetector is largely reduced (from ≈µA to few pA) by etching the p‐GaN, excluding the electrode region. Furthermore, by using a graphene transparent electrode along with the p‐GaN interdigitated fingers on AlGaN/GaN heterostructure, ultraviolet photodetectors with superior sensitivity (3.55 × 106) and ultrahigh detectivity (1.91 × 1014 cm Hz1/2 W−1) are realized at 360 nm. A comparison of graphene/p‐GaN and Ni/Au/p‐GaN interdigitated fingers and planar p‐GaN (with interdigitated graphene contacts) all on AlGaN/GaN heterostructure allows to understand the dominant roles of electrode transparency and the heterojunction structure. The simple and high electron mobility transistor‐compatible fabrication process of UV detectors provides a unique application in the field of UV sensing technology.

Pore-scale Numerical Simulations on the Lean Concentration Methane Combustion in Porous Medium with Gyroid Triply Periodic Minimal Surfaces Structures

ABSTRACT In this work, a series of porous medium with Gyroid Triply Periodic Minimal Surfaces (G-TPMS) structures were established for lean concentration methane combustion. Based on pore-scale numerical simulations, the influence of TPMS parameters on porous media combustions, as well as the shape of flame surface in different TPMS structures, heat transfer characteristics between solids and fluids, the radiation characteristics and heat flux on the solid surface were investigated. Results show that, under the same inlet flow rate and equivalence ratio, the value and axial location of the maximum average fluid temperature will be changed due to the difference in porosity and flow resistance of each structure. For the G-TPMS structures’ porous medium, the change of structure period had a greater impact on the combustion compared with the wall thickness. And, in the G-TPMS structures’ porous medium, the flame surface always shows a finger structure. The flow rate that shows the same increase trend with the fluid temperature in the preheating region, which has a periodic change like the porosity in the axial direction. Based on the results, it can be seen that the region of solid-to-solid surface radiative heat transfer and fluid-solid heat flux on the interface was also changed due to the influence of flame front position.

Multi-Wavelength Biometric Acquisition System Utilizing Finger Vasculature NIR Imaging.

Personal identification using analysis of the internal and external characteristics of the human finger is currently an intensively developed topic. The work in this field concerns new methods of feature extraction and image analysis, mainly using modern artificial intelligence algorithms. However, the quality of the data and the way in which it is obtained determines equally the effectiveness of identification. In this article, we present a novel device for extracting vision data from the internal as well as external structures of the human finger. We use spatially selective backlight consisting of NIR diodes of three wavelengths. The fast image acquisition allows for insight into the pulse waveform. Thanks to the external illuminator, images of the skin folds of the finger are acquired as well. This rich collection of images is expected to significantly enhance identification capabilities using existing and future classic and AI-based computer vision techniques. Sample data from our device, before and after data processing, have been shared in a publicly available database.

Structural and functional characterization of RNA dependent RNA polymerase of Macrobrachium rosenbergii nodavirus (MnRdRp)

Macrobrachium rosenbergii is a highly valued farmed freshwater species and its production has been affected globally by white tail disease caused by M. rosenbergii nodavirus (MrNV). MrNV is a single stranded positive sense RNA virus encoding RNA-dependent RNA polymerase (RdRp) for genome replication. Due to its essentiality for pathogenesis, it is an important drug target. The domain prediction of the complete sequence revealed the presence of two enzymatic regions namely methyl transferase and RdRp separated by transmembrane region. The predicted three-dimensional (3D) structure of MnRdRp using AlphaFold 2 shows that the structure is composed of three major sub-domains common for other polymerases namely fingers, palm and thumb. Structural similarity search revealed its similarity with other flaviviridea members especially with BVDV RdRp (BvdvRdRp). The structure of fingers and palm sub-domains is more conserved than the thumb sub-domain. A small α-helix named ‘priming helix’ having conserve Tyr was identified at position 829–833 with a potential role in de novo initiation. Analysis of electrostatic potential revealed that nucleotide and template channels are electropositive. Metal binding residues were identified as Asp599, Asp704 and Asp705. The α and β phosphates of incoming nucleotide interact with two Mn2+, Arg455 and Arg537. For recognition of 2′–OH of incoming rNTP, Asp604, Ser661 and Asn670 were identified which can form H-bond network with 2′–OH group. Docking study revealed that Dasabuvir can potentially inhibit MnRdRp. The study concluded that the overall structure and function of MnRdRp are similar to Flaviviridae polymerases and their inhibitors can work against this enzyme. Communicated by Ramaswamy H. Sarma

Multiple Tendon-inspired Sensors for Hand Motion Detection

Realistic presentation by a virtual avatar and detection are critical in a motion tracking system. Specifically, because the hand is an essential body part that interacts with other objects or humans in a virtual environment, accurate behavior tracking in real time is required. In this study, we propose a hand motion detection glove using multiple tendon-inspired sensors. Remarkably, there are no sensors or electronics in the hand part of the glove. Piezoelectric sensors are positioned on the wrist part of the glove, which are connected to the tendon in the glove. The elongated piezoelectric sensors detect the angle from joint changes caused by motions of the hand. In addition, we design a case for installing multiple sensors on many joints of the fingers. To demonstrate the sensing ability of the bending motion of the finger, a series of sensor tests is conducted using a finger structure setup. We obtain sensing results with changes in the rotational angles and frequencies. Moreover, the rotational angle can be estimated from the sensing data. Based on these results, a virtual hand system following real hand motion is constructed utilizing a motion detection glove with multiple tendon-inspired sensors. Finally, we investigate the effects of Young’s modulus, number of threads, and the structure of the elastic thread to enhance the output of the sensors.

Numerical simulation of density-driven non-Newtonian fluid flow

Abstract Density-driven flow is numerically studied. The sinking fluid is set as a power-law non-Newtonian fluid with a higher density than the environmental fluid. During the simulation process, saturation concentration is fixed on the upper boundary; thus downward plumes are formed because of gravitational instability. The dissolution flux undergoes a series of changes, from the initially diffusion-dominated regime to the convection-dominated regime due to the appearance of finger structures, and then to the transition of finger structures merging into larger plumes. Finally, it enters the shutdown regime as the plumes start to reach the impermeable bottom boundary. In the process of plume sinking, different fluid properties have an important impact on the downward velocity, shape of plumes and the dissolution flux of the flow field. The tip velocity of the plumes is slowed until the high-concentration fluid is supplied to further push the plumes downward. For the shear-thinning fluid ambient fluid, this phenomenon is even more drastic. However, for shear-thickening fluid, this phenomenon is almost not observed. In addition, unlike the condition of a Newtonian fluid, protoplumes on the original interface appear at the early stage. Prominent protoplumes have developed between the primary plumes in non-Newtonian fluids throughout the entire process.

DOF transcription factors: Specific regulators of plant biological processes.

Plant biological processes, such as growth and metabolism, hormone signal transduction, and stress responses, are affected by gene transcriptional regulation. As gene expression regulators, transcription factors activate or inhibit target gene transcription by directly binding to downstream promoter elements. DOF (DNA binding with One Finger) is a classic transcription factor family exclusive to plants that is characterized by its single zinc finger structure. With breakthroughs in taxonomic studies of different species in recent years, many DOF members have been reported to play vital roles throughout the plant life cycle. They are not only involved in regulating hormone signals and various biotic or abiotic stress responses but are also reported to regulate many plant biological processes, such as dormancy, tissue differentiation, carbon and nitrogen assimilation, and carbohydrate metabolism. Nevertheless, some outstanding issues remain. This article mainly reviews the origin and evolution, protein structure, and functions of DOF members reported in studies published in many fields to clarify the direction for future research on DOF transcription factors.

Experimental study of viscous fingering in sand-pack model for heavy oil reservoir

Viscous fingering phenomenon in porous media has a great impact on industrial processes, such as enhanced oil recovery processes. The previous experimental works mainly used Hele-Shaw models and micromodels to investigate viscous fingering mechanisms. However, Hele-Shaw models simulate porous media flow in a narrow gap with no pore structure. Micromodels’ pore structures are simplified, and the material used to make micromodel generally has different wettability compared with real rocks. Therefore, a large-dimensions of 40 cm × 20 cm× 0.5 cm sand-pack model with a vertical well in the center is used in this study to mimic real reservoir in terms of pore structure, wettability conditions and real radial flow. To the best of our knowledge, there is no reported literature on viscous fingering experimental study for radial flow in real sand-pack models. Immiscible flooding processes with high viscosity ratios ranging from 853.9 to 32080 and different injection rates ranging from 0.01 to 0.5 ml·min−1 were conducted. The viscous fingering phenomena were captured and analyzed qualitatively and quantitatively. As capillary number increases, more unstable interfaces and complicated finger structures were visually observed and validated through fractal dimension analysis. These experimental results are in well agreement with previously reported results obtained from Hele-Shaw models and micromodels. The dimensionless number (Ca*µr2) analysis suggests viscosity has a greater effect on viscous fingering compared with injection rate, which was consistent with the conclusion of micromodel studies. Besides critical injection rate (0.01–0.05 ml∙min−1), increasing the viscosity ratio to a critical viscosity ratio (2946) leads to a significant decrease of breakthrough time, which was not reported in the literature. And different from linear displacement in which the viscous fingering followings two stages, additional pseudo-stable displacement could be generated after the rapid finger generation stage and combination stage for the radial displacement.

Impact of interfacial rheology on finger tip splitting.

Fluid-fluid interfaces, laden with polymers, surfactants, lipid bilayers, proteins, solid particles, or other surface-active agents, often exhibit a rheologically complex response to deformations. Despite its academic and practical relevance to fluid dynamics and various other fields of research, the role of interfacial rheology in viscous fingering remains fairly underexplored. A noteworthy exception is the work by Li and Manikantan [Phys. Rev. Fluids 6, 074001 (2021)2469-990X10.1103/PhysRevFluids.6.074001], who used linear stability analysis to show that surface rheological stresses act to stabilize the development of radial viscous fingering at the linear regime. In this paper, we perform a perturbative, second-order mode-coupling analysis of the system and investigate the influence of interfacial rheology on the morphology of the fingering structures at early nonlinear stages of the dynamics. In particular, we focus on understanding how interfacial rheology impacts the emblematic finger tip-widening and finger tip-splitting phenomena that take place in radial viscous fingering in Hele-Shaw cells. We describe the viscous Newtonian fluid-fluid interface by using a Boussinesq-Scriven model, and derive a generalized Young-Laplace pressure jump condition at the fluid-fluid interface. In this framing, we go beyond the purely linear description and use Darcy's law to obtain a perturbative mode-coupling differential equationwhich describes the time evolution of the perturbation amplitudes, accurate to second order. Our early nonlinear mode-coupling results indicate that regardless of their stabilizing action at the linear regime, interfacial rheology effects favor finger tip widening, leading to the occurrence of enhanced finger tip-splitting events.