Open Grooves Research Articles

Abstract 904: AI platform provides an EDGE and enables state-of-the-art identification of peptide-HLAs for the development of T cell inducing vaccines

Abstract T cell inducing vaccines are key for the development of effective therapies against cancer and infectious diseases. Peptides, presented by Human Leukocyte Antigens (HLAs), are the targets of T cells, and their identification is therefore critical to the development of such vaccines. Here, we present the latest improvement in our EDGETM (Epitope Discovery for GEnomes) platform to address this critical need. EDGE is comprised of AI models that can predict peptide presentation by HLA class I and class II. Although the models are trained primarily using immunopeptidomics data, EDGE scores are predictive of peptide-HLA immunogenicity. There are three class I presentation models in EDGE: an allele-specific model, a pan-specific model, and a model specific for infectious diseases. The allele-specific model is applicable to a large but pre-defined set of HLA alleles. On a large test dataset, the allele-specific model achieved an average precision (AP) of 63% (PPV40=79%) compared to the AP of a standard best-available public model of 21% (PPV40=28%). A Ph1/2 clinical study of personalized cancer vaccines encoding neoantigens predicted from the allele-specific model demonstrated a ~50% molecular response (defined as >=30% reduction in circulating tumor DNA relative to baseline) rate with associated extended overall survival (vs non-responders) in metastatic, microsatellite stable colorectal cancer patients. We observed that >50% of the mutations were able to elicit T cell responses. The pan-specific class I model uses HLA sequences as input feature when training and, therefore, is applicable to any HLA. On the same test dataset as above, it achieved an AP of 65% (PPV40=81%) and performed better on average for ~40 less-common HLA alleles. Prediction of viral peptide presentation by HLA class I is challenging due to the lack of immunopeptidomics data. The class I model for infectious diseases was specifically optimized to predict for viral peptides and, therefore, performed better than available class I models on published HIV and Influenza A datasets. Prediction of peptide presentation by HLA class II is challenging due to the flexibility in how the longer peptides interact with open HLA grooves as well as the lack of immunopeptidomics data as compared to the class I peptides. The class II model in EDGE, EDGE-II, uses the latest developments in protein large language models, a novel learned HLA allele-deconvolution strategy, and in-house immunopeptidomics data, resulting in improved prediction of peptide presentation by HLA class II and immunogenicity driven by CD4+ T cells. On a benchmark validation dataset, EDGE-II achieved an AP of 71% as compared to AP of 62% of a leading published model. In summary, EDGETM provides a comprehensive state-of-the-art platform for the development of vaccines that can induce both CD8+ and CD4+ T cell responses to provide durable benefit to patients. Citation Format: Joshua Klein, Daniel Sprague, Monica Lane, Meghan Hart, Olivia Petrillo, Italo Faria do Valle, Matthew Davis, Andrew Ferguson, Andrew Allen, Karin Jooss, Ankur Dhanik. AI platform provides an EDGE and enables state-of-the-art identification of peptide-HLAs for the development of T cell inducing vaccines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 904.

Numerical simulation and experimental study of optimized jet shape in electric arc electrochemical composite machining

A favorable flow field enhances the product transport capacity and also increases the electrochemical mass transfer rate. In this paper, an end-side connected electrode suitable for electric arc electrochemical composite milling was proposed based on the existing flushing form. The aim is to simultaneously enhance the machining of the groove surface and the side. The flushing form was optimized by the flow field, and it was shown that the internal flushing increased the area of the high flow rate zone of the bottom gap. In the experiments, it was found that the internal flushing reduced the secondary discharge probability, the accumulation of re-solidified material on the groove surface was decreased, and the surface dissolution was uniform with low oxidation. However, the central jet is lost along the course and a zero velocity zone exists at the corners of the groove. Therefore, the sidewall open flow field is proposed to reduce the sidewall recast layer. It was verified that the sidewall slots of the positive flow type improved both the surface quality of the groove surface and the side wall. It was also found that the increase in the number of open grooves facilitates the generation of uniform debris removal.

Analysis of filtering and refractive index sensing characteristics based on gold-coated photonic crystal fiber

A gold-coated photonic crystal fiber (PCF) with dual functions of filtering and refractive index sensing is proposed. The gold layer is deposited in two open grooves, which make it easy to manufacture. For the filtering characteristics, it can achieve high loss at the wavelength of 1550 nm. The results show that the confinement losses of the x - and y -polarized modes are 0.012 dB/cm and 445.10 dB/cm, respectively. When the crosstalk is greater than 20 dB, it shows high bandwidth of 910 nm for the PCF length of 3 mm. For the sensing characteristics, it shows a maximum sensitivity of 4000 nm/RIU for an analyte range of 1.39–1.40. It also has a high figure of merit with a maximum value of 45.45 R I U − 1 and a low detection limit (56.13 nm). Owing to the excellent performance of the gold-coated PCF in filtering and sensing, it will become a suitable candidate for optical communication and sensing systems.

Fault detection in rotor system by discrete wavelet neural network algorithm

This study identifies a method for detection of irregularities such as open cracks or grooves on a rotating stepped shaft with multiple discs, based on the wavelet transforms. Cracks are represented as reduction in diameter of shaft (groove) with small width. Single as well as multiple grooves are considered on stepped shaft at locations of stress concentration. Translational or rotational response curves/mode shapes are extracted from finite element analysis of rotors with and without grooves. Discrete and continuous 1D wavelet transforms are applied on resultant response curve or mode shapes. The results show that rotational response curves or mode shapes are more sensitive to shaft cracks and key contributors to identify the location of cracks than translation response curves or mode shapes. Discrete wavelet transforms are accurate enough to locate the groove of smaller size. Effectiveness of detection by wavelets transforms is analysed for single as well as multiple grooves with increase in groove depth. Increase in groove depth can be quantified by increase in wavelet coefficient, and it can be an indicator. White Gaussian noise with low signal-to-noise ratio is added to response curves and analysed for crack location identification. Intelligent techniques such as artificial neural networks are used to quantify the location and depth of crack. Discrete wavelet transforms coefficients are provided as input to the neural network. Feed forward artificial neural networks are trained with Levenberg–Marquardt back propagation algorithm. Trained networks are able to quantify the crack location and depth accurately.

Determining the effect of stator groove geometry in a traction synchronous reluctance motor with permanent magnets on the saw-shaped electromagnetic moment level

This paper reports the model of a magnetic field of the synchronous reluctance motor with permanent magnets that was developed on the basis of a finite-element method. The model was implemented in the FEMM finite-element analysis programming environment involving the application of the Lua-based script. The model makes it possible to determine the dependence of the engine's electromagnetic moment on the rotor rotation angle. Determining the level of a saw-shaped moment is important for assessing its harmful effect on the structural elements of the traction motor and the drive in general. The results of digital modeling have established the dependences of the electromagnetic moment on the rotor rotation angle. The moment has a variable component – the saw-shaped moment, whose amplitude for open grooves under a rated load mode is 182 Nm, and for semi-open grooves ‒ 90 Nm. The use of semi-open grooves exerts a positive effect on eliminating the saw-shaped moment in a synchronous reluctance motor with permanent magnets and may be recommended for further application on engines of this type. Semi-open grooves reduce the opening of the stator groove by 2 times and lead to a smoother flux distribution under the gear division. That reduces the oscillations of the main magnetic flux. The proposed application of semi-open stator grooves makes it possible to reduce by more than 2 times the level of a saw-shaped moment of the synchronous reluctance motor with permanent magnets under a rated mode. It has been determined that a rather positive factor is an increase of 4.8 % in the average motor moment value under a rated mode when using semi-open grooves. This is due to a decrease in the average value of magnetic resistance to the main magnetic flux. Therefore, with a simultaneous decrease in the moment's fluctuations, the transition to semi-open grooves makes it possible to improve the mass-dimensional indicators of the motor in general.

Аналіз методів фінішного оброблення прецизійних кульок

Аналіз методів фінішного оброблення прецизійних кульок Прикладом елеваторної обробки кульок служить пристрій для доводки кульок, розміщених між двома співвісно розташованими дисками, в нижньому з яких, установленому з можливістю обертання, виконані концентричні канавки. Дане пристосування забезпечує впорядкований рух кульок в робочій зоні і перевід їх з одної доріжки на другу, в результаті чого значно збільшується продуктивність і якість обробки.[1] Був розроблений новий ексцентричний доводочний верстат, власні прототипи авторів. Основна відмінність між цим ексцентриковим доведенням і звичайним концентричним доведенням полягає в тому, що введено зміщення між обертовою віссю і центром кругової V-подібної канавки на нижньому диску-притиру, а верхній диск-притир є плоский і нерухомий. Були проведені експериментальні дослідження з дисками-притирами з м'якої сталі для доведення двох типів куль з нітриду кремнію, отриманих гарячим ізостатичним пресуванням.[2] Спроби вирішити проблему продуктивності привели до створення схем безцентрового шліфування кульок на станках з повздовжньою подачею. На відміно, від відомої схеми обробки циліндричних заготовок провідний круг був виконаний з гвинтовою канавкою несиметричного профілю, а шліфувальний круг оснащений кільцевими канавками. Таке рішення забезпечило обертання кульок від сильного тертя з провідним кругом та додатковим обертанням за рахунок періодичного переривання контакту із шліфувальним кругом. Основна перевага розробленого методу обробки полягає у високій продуктивності процесу. [3] Завдання вирівнювання сітки слідів обробки на поверхні кульок досягається тим, що введені один або більше пружних гальмівників, закріплених на станині верстату з боку відкритих пазів сепаратора так, що завдяки гальмуванню забезпечують додаткове обертання ненавантажених кульок навколо нормалі до площини їхнього руху, що й забезпечує вирівнювання сітки слідів обробки на поверхні кульок завдяки періодичному змінюванню положення миттєвої осі обертання під час руху однією канавкою, що сприяє підвищенню геометричної точності оброблюваних кульок і насамкінець продуктивності обробки невеликих партій кульок.[4] Analysis of finishing methods for precision balls- An example of elevator processing of balls is a device for refining balls placed between two coaxial disks, in the lower of which, installed with the possibility of rotation, made concentric grooves. This device provides an orderly movement of the balls in the working area and their transfer from one track to another, resulting in a significant increase in productivity and quality of processing. [1]- A new eccentric sharpening machine was developed, the authors' own prototypes. The main difference between this eccentric adjustment and conventional concentric adjustment is that an offset is introduced between the rotating axis and the center of the circular V-groove on the lower grinding disc, and the upper grinding disc is flat and stationary. Experimental studies were performed with mild steel grinding wheels to prove two types of silicon nitride balls obtained by hot isostatic pressing. [2]- Attempts to solve the problem of productivity have led to the creation of schemes of centerless grinding of balls on machines with longitudinal feed. In contrast to the known scheme of processing cylindrical workpieces, the guide wheel was made with a helical groove of asymmetrical profile, and the grinding wheel is equipped with annular grooves. This solution provided the rotation of the balls from strong friction with the driving wheel and additional rotation due to the periodic interruption of contact with the grinding wheel. The main advantage of the developed processing method is the high productivity of the process. [3]- The task of leveling the grid of traces of processing on the surface of the balls is achieved by introducing one or more elastic brakes mounted on the frame of the machine from the open grooves of the separator so that by braking provide additional rotation of unloaded balls around normal to the plane of their movement. grids of traces on the surface of the balls due to periodic changes in the position of the instantaneous axis of rotation when moving in one groove, which improves the geometric accuracy of the processed balls and finally the productivity of processing small batches of balls. [4]

Dynamic Analysis of Multi Disc Rotating Stepped Shaft Through Signal Processing

This study identifies a method for detection of irregularities like open cracks or grooves on a rotating stepped shaft with multiple discs, based on the Wavelet Transforms. Cracks are represented as reduction in diameter of shaft (groove) with small width. Single as well as multiple grooves are considered on stepped shaft at locations of stress concentration. Translational or rotational response curves/mode shapes are extracted from finite element analysis of rotor with and without grooves. Discrete and continuous 1D wavelet transforms applied on resultant response curve or mode shapes. The results show that rotational response curves or mode shapes are more sensitive to shaft cracks and key contributors to identify the location of cracks than translation response curves or mode shapes. Discrete Wavelet Transforms are accurate enough to locate the groove of smaller size. Effectiveness of detection by Wavelets Transforms is analyzed for Single as well as Multiple grooves with increase in grove depth. Increase in groove depth can be quantified by increase in wavelet coefficient and it can be an indicator.

Laser-assisted fabrication and in vitro verification of functionalized surface for cells biointegration

The paper investigates how the surface relief of an implant affects cell behavior. Currently, most implant manufacturers claim the key impact biocompatibility factor to be surface micro-roughness. We suppose that the interaction between cells and implants also depends on such relief peculiarities as continuous or discontinuous topography, subcellular distance between peaks and presence of porous oxide layer. We have developed the laser processing conditions that provide three different reliefs: «open grooves», «grid» and «close grooves». Along with the micro-roughness characteristics the reliefs differ with their deepness and period of grooves. The surface composition analysis results have shown a sandwich structure consisting of Ti → TiO → Ti2O3Nx → TiO2 (anatase) → TiO2 (rutile). The wettability study has demonstrated superhydrophilicity (CA is 0°) for all reliefs. The quantitative and qualitative analysis of hMSCs proliferation and osteogenic differentiation was performed for 20 days. In vitro study has revealed the topography affects the spatial orientation of cells. The shape and size of the cell nuclei vary with different topographies. We have found continuous «open grooves» structures with the subcellular to cellular period are beneficial for cells' life-sustaining activity. Discontinuous «grid» structures with individual slots might not provide cells with mobility with the least external mechanical effect compared to «open grooves».

Electrochemical sensors-based phosphorus-doped carbon for determination of adenine DNA-nucleobases in living cells

Monitoring DNA–nucleobases and their oxidized forms in living cells is regarded as a biomarker for DNA damage. Adenine (Ad) electrochemical sensor was designed based on phosphorus-doped carbon spherical eye-like structure (P-CES). Spherical electrochemical sensors oriented with abundant multiple directional gates, such as micro-, meso-pores, and open cave-like eyes may lead to design a potential sensor with fast response, low surface charge resistance, high electron diffusion, and functionalized binding active centers to accommodate Ad molecules. The P-CES hierarchically ordered sphere electrode features dense and reactive exposure sites for a variety of additional interactions and flexible mobility surfaces during the detection of Ad. The key role of the circular shape with a rugged surface, multi-hole construction, and open grooves creates an active catalyst of strong binding to the target molecules and facilitate the molecular diffusion inner/outer the electrode surface. Moreover, the doping of P atoms to the hierarchical carbon chain leads to the distortion of sp2-graphitic construction, increases the number of plane edge defects, and induces the functionalization of the abundant active sites. Thus, P-CES provides active transducing element for detection of Ad in its resources (oxidative DNA in living cells) with high sensitivity, good selectivity, excellent stability, and facile reproducibility. The fabricated P-CES shows an ultrasensitive Ad sensor with a limit of detection as low as 0.002 μmolL−1, with a wide linear range of 0.01–0.8 μmolL−1. The Ad liberated from the oxidative-DNA in living cells can be detected with high affinity and sensitivity. The Ad sensor assay can be employed for investigation of DNA damage and deliver information for diagnosis of diseases caused by cell mutation and immune system deficiency.

Snake fang-inspired stamping patch for transdermal delivery of liquid formulations.

A flexible microneedle patch that can transdermally deliver liquid-phase therapeutics would enable direct use of existing, approved drugs and vaccines, which are mostly in liquid form, without the need for additional drug solidification, efficacy verification, and subsequent approval. Specialized dissolving or coated microneedle patches that deliver reformulated, solidified therapeutics have made considerable advances; however, microneedles that can deliver liquid drugs and vaccines still remain elusive because of technical limitations. Here, we present a snake fang-inspired microneedle patch that can administer existing liquid formulations to patients in an ultrafast manner (<15 s). Rear-fanged snakes have an intriguing molar with a groove on the surface, which enables rapid and efficient infusion of venom or saliva into prey. Liquid delivery is based on surface tension and capillary action. The microneedle patch uses multiple open groove architectures that emulate the grooved fangs of rear-fanged snakes: Similar to snake fangs, the microneedles can rapidly and efficiently deliver diverse liquid-phase drugs and vaccines in seconds under capillary action with only gentle thumb pressure, without requiring a complex pumping system. Hydrodynamic simulations show that the snake fang-inspired open groove architectures enable rapid capillary force-driven delivery of liquid formulations with varied surface tensions and viscosities. We demonstrate that administration of ovalbumin and influenza virus with the snake fang-inspired microneedle patch induces robust antibody production and protective immune response in guinea pigs and mice.

Cryo-EM Studies of TMEM16F Calcium-Activated Ion Channel Suggest Features Important for Lipid Scrambling

SUMMARYAs a Ca2+-activated lipid scramblase and ion channel that mediates Ca2+ influx, TMEM16F relies on both functions to facilitate extracellular vesicle generation, blood coagulation, and bone formation. How a bona fide ion channel scrambles lipids remains elusive. Our structural analyses revealed the coexistence of an intact channel pore and PIP2-dependent protein conformation changes leading to membrane distortion. Correlated to the extent of membrane distortion, many tightly bound lipids are slanted. Structure-based mutagenesis studies further reveal that neutralization of some lipid-binding residues or those near membrane distortion specifically alters the onset of lipid scrambling, but not Ca2+ influx, thus identifying features outside of channel pore that are important for lipid scrambling. Together, our studies demonstrate that membrane distortion does not require open hydrophilic grooves facing the membrane interior and provide further evidence to suggest separate pathways for lipid scrambling and ion permeation.

Heterogeneity of neuromasts in a fish without lateral line canals: the pufferfish (Takifugu obscurus) model.

Fish detect water motion with their mechanosensory lateral line. The basic functional unit of the lateral line is the neuromast. In most fish species, neuromasts are located in lateral line canals (canal neuromasts) or on the skin (superficial neuromasts). In this paper, we describe the lateral line system of the pufferfish, Takifugu obscurus If threatened, this fish inflates its body by sucking water into the esophagus. Pufferfish lack a canal system but have neuromasts located directly on the skin or in open grooves. Each groove houses tall, medium and short neuromasts, based on the height of their pedestal. One or more medium neuromasts were always located between two tall neuromasts, and the short neuromasts were scattered between them. Tall neuromasts showed phasic responses to water jets, similar to the canal neuromasts of other fish species. In contrast, the medium and short neuromasts showed tonic responses to water jets. The response properties of nerve fibers that innervated the medium and short neuromasts were similar to those of the superficial neuromasts found in other fish species. Our results suggest that each groove of a pufferfish has two functional groups of neuromasts. This may allow pufferfish to extract spatial and temporal hydrodynamic information, despite the changes in body shape that occur during and after inflation. The short neuromasts at the bottom of a groove most likely supplement the medium neuromasts when the body is maximally inflated.

Contact Pressure and Strain Energy Density of Hyperelastic U-shaped Monolithic Seals under Axial and Radial Compressions in an Insulating Joint: A Numerical Study

In insulation joints, elastomeric U-shaped monolithic seals (UMSs) are replacing O-ring systems because of their enhanced sealing capabilities for the oil and gas industries. UMSs are compressed axially during assembly and radially when pressurized in operation. The reliability of UMSs due to the displacement imposed during assembly and the internal pressure in operation is influenced by the axial compression ratio, thickness ratio (TR), and geometric complexity. In this study, the hyperelastic behavior of elastomeric UMSs under axial and radial compressions is investigated using axisymmetric finite-element analysis. Twelve examples of UMSs with three geometric restraints (open grooves on both sides (type 1), an open groove on one side only (type 2), and no groove (type 3)) and four thickness ratios (TR = 0.25, 0.50, 1.00, and 1.50) are evaluated. To analyze nonlinear elastomeric materials, neo-Hookean constitutive equations are applied and the UMSs are considered as being a nearly incompressible hyperelastic material with a Poisson’s ratio of 0.499. The failure and detachment risks of UMSs are analyzed in terms of the equivalent stress, gap distance, contact pressure, and strain energy density. It is advantageous that the smaller the TR, the smaller the stress distribution. However, the generation of broader detachment regions is observed. Type 1 symmetrically shows the lowest stress distribution and the smallest detachment region, whereas type 3 symmetrically shows the highest values. Type 3 (TR = 0.25) shows the broadest detachment region in the arc-length range from −15.7 to 15.7 mm, whereas the largest gap of 0.7 mm is observed in type 2 (TR = 0.5). For all types, the detachment region disappears completely at TR = 1.0 or higher, which implies that full sealing is occurring. The average contact pressure increases exponentially during axial compression (in assembly) and linearly during radial compression (in operation). The largest contact pressure of 31.5 MPa is observed in type 3 (TR = 1.5), while the lowest is observed in type 1 (TR = 0.25). As for the strain energy density, type 3 at TR = 0.25 shows the largest increase in the strain energy density with 1.75 MJ/m3, while type 1 shows the most stable values of all cases. In conclusion, the lowest risk of failure of a nonlinear hyperelastic UMS was investigated numerically with minor equivalent stress and detachment region with higher contact pressure, which can be taken into account to ensure the reliability of the UMS.

Stainless steel micro fuel cells with enclosed channels by laser additive manufacturing

This study introduces the first steel micro fuel cells with enclosed channel flowfield made by laser additive manufacturing. These are also the first microfluidic devices with enclosed channels made from stainless steel by additive manufacturing. One important benefit of such fabrication methods is ultrafast prototyping, which we made use of in this study to optimize the performance of our fuel cells. The fabrication process consists of preparing a 3D model using a suitable computer-aided design software and then uploading the model file to the laser additive manufacturing machine. This process requires minimal manual intervention. The use of stainless steel as the fabrication material results in extremely durable, robust, chemically and thermally stable devices. Micro fuel cells with three different stainless steel flowfields were fabricated and characterized, two of which with enclosed channels, and one with traditional open grooves. Both enclosed channel flowfield fuel cells produced significantly higher power and current densities compared to the open groove counterpart: the maximum current density obtained was 1.515 A cm−2 and maximum power density was 363 mW cm−2.

A Novel Peptide Binding Prediction Approach for HLA-DR Molecule Based on Sequence and Structural Information.

MHC molecule plays a key role in immunology, and the molecule binding reaction with peptide is an important prerequisite for T cell immunity induced. MHC II molecules do not have conserved residues, so they appear as open grooves. As a consequence, this will increase the difficulty in predicting MHC II molecules binding peptides. In this paper, we aim to propose a novel prediction method for MHC II molecules binding peptides. First, we calculate sequence similarity and structural similarity between different MHC II molecules. Then, we reorder pseudosequences according to descending similarity values and use a weight calculation formula to calculate new pocket profiles. Finally, we use three scoring functions to predict binding cores and evaluate the accuracy of prediction to judge performance of each scoring function. In the experiment, we set a parameter α in the weight formula. By changing α value, we can observe different performances of each scoring function. We compare our method with the best function to some popular prediction methods and ultimately find that our method outperforms them in identifying binding cores of HLA-DR molecules.

Capillary Force-Driven Fluid Flow in Open Grooves with Different Sizes

Penetration of a wetting liquid into open metallic grooves was investigated in this work. Three grooves with different depths but the same width were tested; for each groove, a gently deposited liquid droplet served as the reservoir for liquid penetration. High-speed imaging revealed that, after the initial stage, the penetration in the grooves is in direct proportion to the square root of time, and the penetration is faster in deeper grooves. The maximum penetration speed, corresponding to the moment that a droplet touches a groove, was measured to be in the neighborhood of ; the penetration speed then exponentially decreases with time. It was found that the penetration front profile remains nearly unchanged as the liquid penetrates downstream and appears to form a nearly 45 deg angle with respect to the groove bottom for all three grooves tested. It is hypothesized that the capillary flow in any noncircular capillaries can be described by Washburn’s equation with the tube diameter replaced by the equivalent diameter, which is defined as the contact line length at the liquid penetration front divided by . For the grooves tested in this work, the calculations from Washburn’s equation based on the equivalent diameter match the measurements well.

Electrowetting actuated microfluidic transport in surface grooves with triangular cross section.

Liquids show different static wetting morphologies in open triangular grooves depending upon the wedge angle (ψ) of the groove and the liquid contact angle (θ) with the substrate. Switching between different morphologies can be achieved either by varying the contact angle of the liquid or by changing the wedge angle of the groove. In the present work we manipulate the apparent contact angle of a liquid by electrowetting to switch between liquid morphologies, from droplet to filament, to achieve microfluidic transport of the liquid into open triangular grooves. The static length of liquid filaments in grooves is analyzed as a function of applied voltage for different applied ac frequencies. The dynamic advancement of the filament lengths in grooves is analyzed as a function of time for different applied voltages for two different liquids: first with contact angle greater than the wedge angle and second with contact angle smaller than the wedge angle. Later an exact electrical model is derived to explain the liquid transport in triangular grooves actuated by electrowetting which includes the precise geometry of the liquid morphology.

Evaporation from open microchannel grooves

The evaporation of water from open u-shaped microchannel grooves was investigated with particular emphasis on the roles of channel width and air flow conditions. Given the small dimensions of the microchannels, all measurements were conducted in a range where convection and diffusion are of equal importance and known correlations for the calculation of mass transfer coefficients cannot be applied. The evaporation rates were measured using a new optical method and a gravimetric method. Both measurement methods yielded mass transfer coefficients that are in agreement with each other. The observed relation between mass transfer coefficient, air velocity and channel width vastly differs from the predictions obtained from macroscopic structures. With respect to diagnostic devices we conclude that analyte concentration in an open microchannel groove strongly increases even within short times due to the evaporation process and we show that wider channels are more favourable in terms of minimizing the relative evaporation rate.

Capillary Rise of Liquids over a Microstructured Solid Surface

The location of the triple line as a function of time has been recorded for a series of organic liquids, with various surface tension to viscosity ratios, wicking upward a rough Cu(6)Sn(5)/Cu intermetallic (IMC) substrate. The complex topographical features of such an IMC rough surface are characterized by surface porosity and surface roughness. A theoretical model for wicking upward a rough surface has been established by treating the rough IMC surface as a two-dimensional porous medium featuring a network of open microtriangular grooves. The model is verified against experimental data. The study confirms that the kinetics of capillary rise of organic liquids in a nonreactive flow regime over a porous surface having arbitrary but uniformly distributed topographical features involves (i) surface topography metrics (i.e., permeability, tortuosity/porosity, and geometry of the microchannel cross section); (ii) wicking features (i.e., contact angle and filling factor); and (iii) physical properties of liquids (i.e., surface tension and viscosity). An excellent agreement between theoretical predictions and experimentally obtained data proves, for a selected filling factor η, validity of the analytically established model. Scaled data sets show that, for a given rough surface topography, (i) wicking kinetics of considered liquids depend on properties of liquids, that is, surface tension to viscosity ratios and contact angles; (ii) the filling factor for all tested liquids is an invariant, offering good prediction within the range of ~0.9-1.0. The distance of the wicking front versus square root of time relationship was well established throughout the whole considered wicking evolution time.

The comparative morphology of pit organs in elasmobranchs

The pit organs of elasmobranchs (sharks, skates and rays) are free neuromasts of the mechanosensory lateral line system. Pit organs, however, appear to have some structural differences from the free neuromasts of bony fishes and amphibians. In this study, the morphology of pit organs was investigated by scanning electron microscopy in six shark and three ray species. In each species, pit organs contained typical lateral line hair cells with apical stereovilli of different lengths arranged in an "organ-pipe" configuration. Supporting cells also bore numerous apical microvilli taller than those observed in other vertebrate lateral line organs. Pit organs were either covered by overlapping denticles, located in open grooves bordered by denticles, or in grooves without associated denticles. The possible functional implications of these morphological features, including modification of water flow and sensory filtering properties, are discussed.