Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the application of such structures in light-weight crash absorbers has become conceivable. The present paper therefore elucidates the mechanical behavior of rigid sintered fiber structures under quasi-static and dynamic loading. Special attention is paid to the strongly anisotropic properties observed for different directions of loading in relation to the main fiber orientation. Basically, the structures show an orthotropic behavior; however, a finite thickness of the fiber slabs results in moderate deviations from a purely orthotropic behavior. The morphology of the tested specimens is examined by computed tomography, and experimental results for different directions of loading as well as different relative densities are presented. Numerical calculations were carried out using real structural data derived from the computed tomography data. Depending on the direction of loading, the fiber structures show a distinctively different deformation behavior both experimentally and numerically. Based on these results, the prevalent modes of deformation are discussed and a first comparison with an established polymer foam and an assessment of the applicability of aluminum fiber structures in crash protection devices is attempted. By and large, they belong to the realm of metallic foams or so-called cellular metals. Some research has been performed on the determination of mechanical properties of likewise rigid metallic fiber structures. The available literature on such investigations has been summarized by Veyhl et al.  and goes [et al.  manufact [et al.  have beei.e., the quantification of the fiber structure anisotropy and its influence on the stiffness of the fiber network has been addressed in [i.e., [When comparing results of different research groups, the direction of loading with regard to the morphology of the fiber structure and the nature of the inter-fiber bonds has to be taken into account very carefully as they influence results considerably, essed in . This won [i.e., ); therefr is the relative density, mS the mass of the sample, VS the volume of the sample, and ρ the bulk density of the fiber material.All previous references reveal the same behavior where an increase in relative density results in rising mechanical properties. This is also the case in the present study. The relative density is defined as: i.e., uni-axial tensile and compression testing). In contrast, the current research focuses on the energy absorption and the influence of structural anisotropy both under quasi-static and dynamic loading. It was found that the direction of loading with regard to the anisotropy of the fiber structure exerts a significant influence on the mechanical properties. Moreover, the deformation and failure mechanisms are visibly different. Numerical simulation confirmed a high anisotropy of sintered metal fiber structure (SMFS) specimens. In the case of the loading direction parallel to the main fiber orientation they revealed that the deformation is distributed along the metallic fibers  while, in the case of the loading direction perpendicular to the main fiber orientation, a layer-wise deformation mode  has been observed.The aforementioned research was mainly based on experimental quasi-static testing  but different direction of loading are intersecting at a relative deformation of approximately 25% to 50%. In other words, loading parallel to the main fiber orientation results in a more “typical” compression behavior: a pronounced quasi-elastic rise in the beginning, a comparably long and flat plateau region, and, finally, a strong rise in stress due to the onset of densification. Deviations within one set of samples can be most likely attributed to variations of density of the individual samples see also .For dynamic testing, a procedure as described in i.e., no barreling, but a layer-wise collapse mechanism, leading to lower yielding and lower plateau stress.The resulting compressive stress-strain curves are given in A strong influence of the relative density and the direction of loading on the measured stress can be observed. In particular, note that the set of curves of samples of the same relative density but different direction of loading are intersecting at a relative deformation of approximately 20% and 55%, respectively. In other words, loading parallel to the main fiber orientation results in a more “typical” compression behavior: a pronounced quasi-elastic rise in the beginning, a comparably long and flat plateau region, and, finally, a strong rise in stress due to the onset of densification. In that regard, there seems to be no difference between quasi-static and dynamic testing conditions.Deviations within one set of samples can be most likely attributed to variations of density of the individual samples. In general, deviations within one set of samples are smaller than in quasi-static testing which corresponds well to the smaller relative deviations in density compared to the quasi-static test samples see also .Two distinct deformation modes can be observed depending on the direction of loading relative to the main fiber orientation. At the same sample relative density level, loading parallel to the main fiber orientation results in an initially much stiffer behavior than loading perpendicular to the main fiber orientation. However, under both quasi-static and dynamic loading, we observe that at higher deformations  the initially stiffer parallel testing direction becomes softer than the perpendicular testing direction. The different sample deformation behavior as shown earlier in Again, we observe that for samples of comparable density, both under quasi-static and dynamic loading the initially stiffer parallel testing direction becomes softer than the perpendicular testing direction at larger deformations.In , severalOn the other hand, plastic deformation of metals is occurring through a number of thermally activated processes such as dislocation glide. As was already shown earlier, the samples undergo measurable heating-up during dynamic testing. Average temperature rises of up to 20 K were measured although the loading velocity for the tested specimens was moderate (284 mm/s). However, as the spatial resolution of the IR thermography is low and heat dissipates quickly along the fibers, the local temperature rise at the actual sites of plastic deformation is assumed to be much higher. Therefore, the lower energy consumption during dynamic testing is attributed to dynamic softening of the samples due to the rise in temperature at the very sites of plastic deformation.It is conceivable that the pronounced dependence of the compression behavior on the testing direction might be due to a prevalence of fiber buckling and rupture of bonds in the direction parallel to the main fiber orientation. This hypothesis is strongly supported by the numerical calculations.In addition to the general difference in the deformation behavior in dependence of the testing direction, an influence of the different fiber diameters used for the dynamic and the quasi-static test samples cannot be ruled out. The dynamic test samples with a relative density of 0.3 were made from thicker fibers which thus boast a lower number of inter-fiber bonds. On the other hand, for a fiber with a cylindrical cross section the resistance to buckling scales with the fourth power of the fiber diameter. As the melt-extracted fibers generally show a more flattened-out cross-section, the limiting case of a rectangular cross section may be assumed where the second moment of inertia scales with the third power of the lateral length. Hence, without a very detailed analysis of the average length between the fiber contacts, it is not possible to determine whether the change in distance between the fiber bonds or the increase in buckling strength due to the larger fiber diameter is the dominating effect.Due to the fact that the dynamic testing samples were prepared from a plate-like parent structure as described in ®, Evonik Resource Efficiency GmbH, Essen, Germany) shows comparable compressive deformation stress levels and constitutes a relevant benchmark for lightweight crash absorption applications. Chu et al. [® samples in a drop tower. The main parameters of these tests were as follows:Sample dia. 80 mm, length 75 mm3Foam density 110 kg/mDrop tower test speed 7 m/s, punch weight 40 kgDue to their low deformation stress levels, aluminum fiber structures may be compared to polymer foams in terms of specific energy absorption at a given stress level. Here, a commercially available closed-cell polymethacrylimide (PMI) polymer foam , which was about 25% less than in the quasi-static tests and slightly lower than the data provided by the foam manufacturer. ® 110IG. The foam shows an almost constant stress level (plateau stress) of approx. 2 MPa up to 60% strain. It is, therefore, possible to utilize the foam within this deformation range. The weight specific energy absorption of the tested ROHACELL® specimens at 60% strain EA60 results to 11.2 kJ/kg. The value for EA60 given by the manufacturer is 16.5 kJ/kg; however, the specific test conditions used by the manufacturer are not known.From the measured data, a specific energy absorption of 1.23 MJ/m® foam can be taken from 3 and a weight specific EA40 of 7.2 kJ/kg. In comparison, the data of the fiber sample were as follows:3Fiber material AlCu5, relative sample density 0.16, absolute sample density 480 kg/m3 at a maximum stress of 2.26 MPa. This is reasonably close to the plateau stress value of the polymer foamCalculated volume specific energy absorption up to 40% deformation amounts to 0.41 MJ/mA direct comparison of the specific energy absorption should be made only at comparable total deformation and stress levels. The tested aluminum fiber structures show a considerable rise in stress after 40% deformation. Therefore, the specific energy absorption at 40% strain (EA40) values of the foam and a suitable fiber structure  were compared. The EA40 values of the ROHACELL® 110IG polymer foam at 40% strain. In terms of volume specific performance, the tested fiber structure is much denser than the polymer foam and, thus, reaches about 50% of the volume specific performance of the polymer foam.The weight specific energy absorption of the aluminum fiber sample amounts to 0.86 kJ/kg which is about 12% of that of ROHACELLThe dynamic behavior of SMFS specimens was further studied by numerical simulation. The deformation of SMFS subjected to compressive loading parallel and perpendicular to the main fiber orientation is shown in The advantage of computational simulation in comparison to experimental testing is the possibility to observe also the specimen’s interior local deformation mechanics in detail. The comparison between the experimental and numerical response of SMFS with different relative densities (0.3 and 0.16), loading velocities (30/s and 100/s), and directions are shown in the diagrams in Additionally, a positive strain rate sensitivity of SMFS specimens has been observed. This is in contradiction to the experimental results and can be attributed to the omission of thermal effects in the computational simulations, while the same fiber geometry has been used at different strain rates which was not possible in the case of experimental testing.In case of the testing direction perpendicular to the main fiber orientation, the numerical response indicates higher stresses in comparison to the experimental measurements for SMFS specimens with higher relative density. The yield stress and plateau stress are higher with respect to the experimental values. The difference in the response might be attributed to the initial compaction of fiber layers (softer in manufactured specimens) in the first loading steps and the connection between single fibers . Also, a distinctive transition between the plateau and densification regions could not be captured exactly, which can be mainly attributed to the failure mechanism applied in the numerical models. In case of the perpendicular loading of SMFS specimen with lower relative density again a good comparison through complete macroscopic strain range can be noted.The experimental and numerical values of plateau stress and plateau modulus for tested SMFS specimens (both loading directions) are presented in In order to produce aluminum fiber structures, a liquid phase sintering route has been developed requiring aluminum alloy fibers with appropriate composition and clean surface. This can be accomplished by utilizing the crucible melt extraction (CME) process by which it is possible to manufacture short fibers from almost any fusible material. To this end, a rotating wheel with a notched surface is placed over a melt pool. The rotating extraction device is water cooled and, thus, generates a high solidification rate. As a result, homogenous distribution of the alloying elements, small grain sizes, reduced segregation, and extended solubility, as well as the formation of metastable phases, can be achieved. The melt extracted fibers typically show a sickle or kidney shaped cross-section. Fraunhofer IFAM Dresden has improved the crucible melt extraction process to produce fibers of a mean equivalent diameter from 50 to 250 µm. The mean fiber length is usually in the range of 3 to 25 mm. The manufacturing process is described in greater detail in . The maiNote that the number of fibers contained in a sample of a fixed volume increases linearly with increasing relative density of the sample, holding the fiber diameter constant. This implies that, at the same time, the number of contact points has to increase non-linearly due to the simple fact that the number of contact points approaches infinity with the sample approaching full density or a relative density of 1. This is in contrast to the explanations given in . For insThe sintered metallic fiber structures reveal a strong orthotropy due to the fiber laying technique. Sintering of the aluminum fibers was carried out in nitrogen or vacuum atmosphere at temperatures slightly above the solidus. For this study, a composition of 95 wt % Al and 5 wt % Cu was used. The amount of liquid phase during sintering is typically around 20 vol %. By applying a weight on top of the fiber deposit during sintering, the porosity of the fiber structures can be set to anywhere between approximately 50% and 90% and is completely interconnected. The pore size usually lies between 10 and 250 µm, depending on the porosity and the fiber diameter.3 were prepared from sintered fiber structures (“plates”) of thickness 10 mm. z-direction corresponds to the testing direction perpendicular to the main fiber orientation, which is the x-y plane corresponds to the plane of the linear table during fiber deposition.For quasi-static testing, cylindrical samples  were cut out from a larger block of sintered aluminum fibers by wire electro discharge machining. For dynamic testing, cubes with dimensions 10 × 10 × 10 mmDue to the large height of the blocks used as parent structures for the cylindrical samples, a density gradient from top to bottom of the blocks was observed, resulting in a larger scatter of individual sample densities as compared to the dynamic testing samples. The maximum deviation from the mean value within one set of quasi-static test samples reached −7.8% and +6.7%, respectively. In contrast, the maximum deviation from the mean value within one set of dynamic test samples reached only −3.4% and +3.8%, respectively.For quasi-static testing, a procedure in accordance with DIN 50134 was adopted. Testing was carried out at Fraunhofer IFAM, Dresden, Germany, on a Hegewald & Peschke Inspekt table  with a 100 kN load cell. The strain rates were 0.1%/s (corresponding to 0.01 mm/s) between 0% and 10% strain and 1%/s (corresponding to 0.1 mm/s) at higher strain. Compressive loading was achieved by moving the upper plate which is attached to the machine crosshead downwards towards the fixed pressure plate. The finite stiffness of the testing machine was compensated by measuring displacement directly between the pressure plates using an external extensometer.3) SMFS specimens, their mass, relative density, and testing conditions are given in The dynamic compressive experimental testing was performed at the University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Croatia, using the servo-hydraulic testing machine INSTRON 8801  according to the standard ISO 13314:2011 ,10. The The loading velocity was set to 284 mm/s which resulted in a macroscopic compressive strain rate of approx. 30/s. The testing machine support plates were lubricated with the graphite-based silicone grease to minimize the friction between the specimens and the support plates. During the tests, the force and cross-head displacement have been recorded to evaluate the compressive mechanical properties. The measured load-displacement data during testing were converted using the initial specimen’s dimensions to compressive stress-strain values.The experiments were also captured with a Full HD video camera SONY HDR-SR8E , supporting recording at 100 frames per second, and an infrared (IR) thermal camera. The IR thermography allows one to observe and follow the deformation mechanics ,12. In  it was ci.e., Alporas® [® [The highly complex geometry of SMFS specimens has been captured and reconstructed based on the micro-computed tomography (μCT) which is already a well-established method for preparation of computational models of various porous materials, Alporas® , M-Pore®oras® [® , Advanceoras® [® , expandeoras® [® , and aluoras® [® . The μCToras® [® . After tGeometrical and mechanical convergence of the numerical model requires a sufficient number of finite elements to accurately represent the complex geometry of analyzed structure. To ensure both geometrical and numerical convergence, preliminary parametric sensitivity studies have been performed. It has been observed that ~1.4 million fully integrated tetrahedron finite elements allow to accurately describe the response of the considered SMFS model .E = 70 GPa, Poisson’s ration ν = 0.35, yield stress σy = 200 MPa, tangent modulus Et = 200 MPa and failure strain εf = 0.5. When the plastic strain in a finite element exceeds the prescribed failure strain, the finite element is effectively removed from the finite element model.The mechanical properties of the SMFS base material AlCu5 have been considered using the bilinear material model with von Mises plasticity: Young’s modulus The boundary conditions of the finite element analysis combine displacement controlled loading, a fixed planar rigid wall at the opposite specimen’s surface simulating uniaxial compressive loading and the double symmetry boundary conditions on the two adjacent vertical surfaces . Two dynThis study provides experimental and numerical results for sintered aluminum fiber structures regarding their energy absorption and the influence of structural anisotropy both under quasi-static and dynamic loading. In addition the well-known influence of the relative density on the mechanical properties, it was found that the direction of loading with regard to the anisotropy of the fiber structure also exerts a significant influence. Moreover, the global deformation and failure mechanisms are visibly different. Numerical simulation based on CT scans confirmed a high anisotropy of sintered metal fiber structure (SMFS) specimens. In the case of the loading direction parallel to the main fiber orientation they revealed that the deformation is distributed along the metallic fibers, while in the case of loading perpendicular to the main fiber orientation, a layer-wise deformation mode has been observed.The observed stress-strain curves follow the typical pattern of open- and closed-cell cellular metals under compressive loading: an initial strong rise in stress (quasi-elastic region) is followed by a comparably moderate rise in stress  and a third region with another strong rise in stress . In particular, loading parallel to the main fiber orientation results in a more “typical” compression behavior: a pronounced quasi-elastic rise in the beginning, a comparably long and flat plateau region, and finally a strong rise in stress due to the onset of densification. This observation is independent of the speed of deformation examined in the reported experiments.i.e., loading parallel to the preferred fiber orientation results in a strong expansion of the samples accompanied by an initially- strong rise in stress, whereas loading perpendicular to the main fiber orientation leads to almost no changes in the horizontal projection of the sample shape.The energy absorption during dynamic loading was found to be smaller than under quasi-static loading. This was attributed to dynamic softening resulting from a rise in temperature of the samples during testing. Due to the pronounced orthotropy of the fiber structures, a strong dependence of the deformation behavior on the direction of loading can be observed. The performance of the aluminum fiber structures in terms of energy absorption was compared to that of a commercially available closed-cell high-density polymer foam. At comparable stress and strain levels, the weight specific performance of an aluminum fiber sample with a relative density of 0.16 reached 12% and the volume specific performance 50% of the values of the polymer foam. This is better than expected and could be further optimized by using materials with better strength-to-weight ratios, such as high-strength aluminum alloys, as well as titanium or steel fibers.A shortcoming of this study is the use of different parent structures and sample geometries for the sample sets for quasi-static and dynamic testing. Although it is most likely that the relative density of the fiber structure and the direction of loading constitute the most relevant parameters for the mechanical performance, further studies should be carried out on sample sets prepared from the same parent structure. Additionally, future work should also provide more insight into the microstructure before and after testing in order to provide a better understanding of the governing deformation and failure mechanisms on the microscopic level.


Covalent organic frameworks with high porosity and crystallinity have been synthesized, through macrocycle-to-framework strategy, using shape-persistent arylene-ethynylene macrocycles as the key components to control the topology and modulate the porosity. Macrocycle-to-framework strategy was explored to prepare covalent organic frameworks (COFs) using shape-persistent macrocycles as multitopic building blocks. We demonstrate well-ordered mesoporous 2D COFs (AEM–COF-1 and AEM–COF-2) can be constructed from tritopic arylene-ethynylene macrocycles, which determine the topology and modulate the porosity of the materials. According to PXRD analysis and computer modelling study, these COFs adopt the fully eclipsed AA stacking mode with large accessible pore sizes of 34 or 39 Å, which are in good agreement with the values calculated by NLDFT modelling of gas adsorption isotherms. The pore size of COFs can be effectively expanded by using larger size of the macrocycles. Provided a plethora of polygonal shape-persistent macrocycles with various size, shape and internal cavity, macrocycle-to-framework strategy opens up a promising approach to expand the structural diversity of COFs and build hierarchical pore structures within the framework. Mesoporous 2D COFs with high surface area, large pore volume, good thermal stability and high crystallinity were successfully prepared from arylene-ethynylene macrocycles. By varying the size of macrocycles, the pore size of the COFs can be systematically tuned.Covalent organic frameworks (COFs) represent a novel class of porous crystalline polymers, in which the building blocks are assembled into two- or three-dimensional architectures through covalent bonds. COFs possess rigid structures, high thermal stabilities, and low densities. Since the pioneering work of Yaghi and co-workers,vC),1 and AEM-2, which closely resemble the commonly used trigonal connector, 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP), were prepared (1 and AEM-2 have similar triangle shape as HHTP (7 Å) but with increased sizes, having the extended lateral lengths of approximately 9 Å and 13 Å respectively. Gram-scale AEM-1 and AEM-2 were obtained from simple dipropynyl monomer 1, or 2 through acyclic diyne metathesis macrocyclization (ADIMAC), followed by deprotection of TBS groups in high yields. Highly active multidentate triphenolsilane-based Mo(vi) carbyne complexAmong various SPMs, arylene-ethynylene macrocycles (AEM) are of our particular interest, since they are perfectly planar and rigid and their size and geometry can be easily tailored.prepared . AEM-1 a1 and AEM-2 as a novel type of multitopic building units, which can modulate pore size/distribution of COFs. We fixed the length of the linker using the same simple 1,4-benzenediboronic acid (BDBA), and varied the size of multitopic connectors: HHTP (7.1 Å), AEM-1 (9.3 Å), and AEM-2 (13.2 Å). For the comparison purpose, COF-5, which was previously reported by Yaghi,1 was obtained in mesitylene/dioxane  by heating the reaction mixture at 100 °C for 7 days without stirring. Although AEM–COF-2 shares a similar structure motif with AEM–COF-1, it requires a different solvent combination. A low surface area material was obtained when AEM-2 and BDBA were heated (120 °C) in mesitylene/dioxane for 7 days. Among various solvent systems we tested , the combination of DMAc/DCB provided crystalline AEM–COF-2 with the highest surface area under conventional heating  or microwave heating . AEM–COF-1 and AEM–COF-2 were isolated as yellow microcrystalline powders through centrifugation followed by successive washing with anhydrous acetone. Both COFs are insoluble in common organic solvents such as alkanes, arenes, acetone, ethers, and N,N-dimethylformamide.Most COFs are generally constructed from two types of building blocks: symmetric multitopic connectors and ditopic spacers. The multitopic connectors not only determine the topologies of the COFs, but also work in tandem with the spacers to determine the pore sizes, pore volumes, surface areas and functions of the COFs. Since there are a rich diversity of ditopic spacers readily available, a common strategy to enlarge pore apertures of COFs with a given topology has been to increase the length of the rigid ditopic linkers.1 and AEM–COF-2 were characterized by FT-IR, 13C-MAS NMR, elemental analysis, TGA, SEM and PXRD analysis. The FT-IR spectra of AEM–COF-1 and AEM–COF-2 show stretching bands of B–O at 1335 cm–1 and 1323 cm–1, respectively. We also observed broad absorption band around 3430 cm–1, which likely corresponds to the residual hydroxyl groups of the macrocycles and boronic acids. In the magic angle spinning (MAS) solid-state 13C NMR spectrum of AEM–COF-1, we observed a single peak at 92.6 ppm which can be assigned to the carbons of triple bonds, indicating the uniformity of the chemical environment around C PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.tbdXn5UH" format="PBM" resolution="300" x-size="34" y-size="34" xml:space="preserve"> 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000	</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="16.000000pt" height="16.000000pt" viewBox="0 0 16.000000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 1760 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z M0 1280 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z M0 800 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z"/></g></svg>C bonds. The 13C NMR spectrum of AEM–COF-2 shows C PBM data was replaced with SVG by xgml2pxml:<glyph-data id="z.tbdw1WYu" format="PBM" resolution="300" x-size="34" y-size="34" xml:space="preserve"> 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 1111111111111111111111111111111111 1111111111111111111111111111111111 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000 0000000000000000000000000000000000	</glyph-data><svg xmlns="http://www.w3.org/2000/svg" version="1.0" width="16.000000pt" height="16.000000pt" viewBox="0 0 16.000000 16.000000" preserveAspectRatio="xMidYMid meet"><metadata>Created by potrace 1.16, written by Peter Selinger 2001-2019</metadata><g transform="translate scale" fill="currentColor" stroke="none"><path d="M0 1760 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z M0 1280 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z M0 800 l0 -80 1360 0 1360 0 0 80 0 80 -1360 0 -1360 0 0 -80z"/></g></svg>C bond carbon peak at 90.7 ppm. Thermogravimetric analysis (TGA) of AEM–COF-1 and AEM–COF-2 shows <10% weight loss at 400 °C and <30% at 800 °C under a nitrogen atmosphere  characterization  measurement. The PXRD patterns of the COFs exhibit intense peak at 2θ = 2.9° and 2.2°, for AEM–COF-1 and AEM–COF-2, respectively, along with some other peaks with lower diffraction intensities, indicating long-range molecular ordering in both COFs. We did not observe diffraction peaks that are characteristic for the starting materials  a fully eclipsed model with an AA stacking (space group P6/mmm), and (ii) a staggered model with an AB stacking (space group P63/mmc). Each layer was translated from the next one by one-half of the a and b lattice parameters. A geometrical energy minimization was performed using the universal force-field implemented in the forcite module to optimize the geometry of the building molecules, as well as the unit cell parameters. The powder diffraction patterns for the models were then calculated and compared with the experimental ones. We found the simulated PXRD patterns of the fully eclipsed models of AEM–COF-1 and AEM–COF-2 are in excellent agreement with experimental results, indicating the eclipsed stacking mode of the layers ; and AEM–COF-2: a = b = 40.935 Å, c = 3.257 Å , both of which agree well with the observed reflections. Therefore, similar to COF-5, AEM–COF-1 and AEM–COF-2 adopt eclipsed stacking of the layers, which lead to 1D mesopores with theoretical diameters of 34 Å and 39 Å respectively.The crystallinity of AEM–COF-e layers . A full 1 and AEM–COF-2 were then investigated by N2 adsorption isotherms at 77 K and the results are summarized in P/P0 = 10–5 to 10–2) followed by a second stage pore filling starting around P/P0 = 0.05, which levels off at a relative pressure of P/P0 = 0.18, 0.25 and 0.35 for COP-5, AEM–COF-1 and AEM–COF-2, respectively. The gradual shift of the step positions suggests the increasing sizes of the pores in these three COFs. Calculations based on the non-local density functional theory (NLDFT) also reveal the trend of increasing pore sizes in the series, showing a narrow pore-size distribution (PSD) centered around 2.6 nm for COF-5, 3.2 nm for AEM–COF-1, and 3.8 nm for AEM–COF-2  predicted from the modelling based on XRD crystal packing. Correspondingly, we observed increasing pore volumes (Vp), which were calculated to be 0.828 cm3 g–1 (COF-5), 1.15 cm3 g–1 (AEM–COF-1), and 1.38 cm3 g–1 (AEM–COF-2) at P/P0 = 0.90. No or little hysteresis loops were observed in the whole range of adsorption–desorption isotherms in all three frameworks. The absence of hysteresis loop has been observed for similar mesoporous MCM-41 with tubular hexagonal pores of sizes <40 Å at temperatures above 77.4 K.2 g–1 (correlation coefficient = 0.998), which is in good agreement with the reported literature value (1590 m2 g–1).1  and AEM–COF-2 . As shown in macrocycle-to-framework strategy to construct ordered crystalline COFs with tunable pore diameters and volumes by varying the dimensions of tritopic macrocyclic building units.The porosities of the frameworks AEM–COF-EM–COF-2 . These v2, which contains AEM-2 with interior void of 5.8 Å. However, we did not observe micropores below 1 nm range. Although the X-ray diffraction data is in excellent agreement with the perfectly eclipsed model of the AEM–COF-2 layered structure, there might be slight offset between the adjacent interlayers, leading to the restricted accessibility of such micropores. In order to obtain COFs with multiple-type pore structures, the use of macrocycles with large intrinsic pores are desired.Initially, we expected hierarchical pore structures in the case of AEM–COF-e.g. arylene-vinylene macrocycles (AVM),macrocycle-to-framework strategy opens up new avenues in the synthesis of COFs with intriguing architectures, properties and applications.We have demonstrated that arylene-ethynylene macrocycles (AEMs) can be utilized as well-defined building blocks for construction of COFs with high thermal stability, permanent porosity, and high crystallinity, either under conventional solvothermal conditions or microwave heating. The π–π interactions between rigid arylene-ethynylene backbones likely contribute considerably to the eclipsed packing of the layers as well as the formation of ordered crystalline materials. Our study shows that the customizable SPMs can be effectively utilized as a new type of multitopic connectors to control the topologies of the COFs and tune the surface area, pore size, and pore volume of the COFs. Given the vast availability of SPMs with different backbones and properties, Supplementary informationClick here for additional data file.


Pruning is applied in order to combat over-fitting problem where the tree is pruned back with the goal of identifying decision tree with the lowest error rate on previously unobserved instances, breaking ties in favour of smaller trees with high accuracy. In this paper, pruning with Bayes minimum risk is introduced for estimating the risk-rate. This method proceeds in a bottom-up fashion converting a parent node of a subtree to a leaf node if the estimated risk-rate of the parent node for that subtree is less than the risk-rates of its leaf. This paper proposes a post-pruning method that considers various evaluation standards such as attribute selection, accuracy, tree complexity, and time taken to prune the tree, precision/recall scores, TP/FN rates and area under ROC. The experimental results show that the proposed method produces better classification accuracy and its complexity is not much different than the complexities of reduced-error pruning and minimum-error pruning approaches. The experiments also demonstrate that the proposed method shows satisfactory performance in terms of precision score, recall score, TP rate, FP rate and area under ROC. Decision tree is one of the most powerful and efficient techniques in data mining which has been widely used by researchers –3. CompaThere are two main pruning approaches: post-pruning and pre-pruning approaches. Post-pruning is implemented after the tree is grown. In practice, post-pruning methods have better performances than pre-pruning . In pre-In the past decades, several post-pruning algorithms have been introduced such as reduced-error pruning, error-complexity pruning, minimum-error pruning, and cost-based pruning. Most of the pruning methods such as reduced-error pruning and minimum-error pruning traverse the decision tree in bottom-up order estimating the misclassification errors for each node to reduce the tree size and to avoid the over-fitting problem.In this paper, we adopt post-pruning approach to combat the over-fitting problem that rises during data classification process and leads to a complex tree with large size and difficult to understand. To avoid this obstacle a new post-pruning method called Pruning with Bayes Minimum Risk (PBMR) is introduced in order to achieve high accuracy with reduced tree size. While post-pruning algorithms estimate the misclassification errors at each decision node, PBMR method estimates the risk-rate of a node and its leaf and then propagates this error up the tree instead of estimating the misclassification errors. If the parent node has a lower risk-rate than its leaf, the parent node is converted to a leaf node, otherwise, the parent node is retained. Several experiments are conducted to investigate the effectiveness of proposed PBMR method and its results are compared with the results of reduced-error pruning and minimum-error pruning approaches.A decision tree is a flowchart-like tree structure, where each internal node denotes a test on an attribute, each branch represents an outcome of the test, and each leaf node holds a class label. Decision trees suffer from over-fitting problem that appears during data classification process and sometimes produce a tree that is large in size with unwanted branches. Pruning methods are introduced to combat this problem by removing the non-productive and meaningless branches to avoid the unnecessary tree complexity.The advance progresses in information technologies result in a large amount of data that needs to be analysed and managed to gain useful information knowledge to predict future behaviour. Several types of research that the details will be discussed in Related Works section, have been conducted in the literature to store and manipulate this valuable data for further decision making. Although, decision tree is one of the most widely used data mining methods, it may provide very large trees in size. To overcome this problem several approaches such as pruning methods are introduced for optimizing the computational efficiency of the tree with high accuracy.The contributions of this paper are the following:The paper indicates the importance of employing attribute evaluator methods to select the attributes with high impact on the dataset that provide more contribution to the accuracy.A new post-pruning method named as PBMR is introduced to overcome over-fitting problem and also to improve the accuracy performance.Several post-pruning algorithms for decision trees such as reduced-error pruning, pessimistic pruning, error-based pruning, cost-complexity pruning and minimum-error pruning have been introduced in the literature –11. Eachk is computed as following:Lk(ai|Cj) and pk(Cj|x) are the loss function when an example is predicted in class Cj while true class is Ci and the estimated probability of an example belonging to Cj, respectively and Tc is the total number of classes. The total risk of the leaves can be calculated as:Tl is the total number of leaves under the subtree.As defined in , 21, BayIn the proposed algorithm, a decision tree algorithm is used to build and initiate a tree model. Then linear regression method is applied to build models on leaves level of the tree. The proposed modified decision tree algorithm is implemented recursively with the following sequence until the tree is formed. Proposed algorithm adopts a post-pruning bottom-up method for C4.5 decision tree algorithm using Bayes minimum error method that estimates risk-rates instead of estimating the misclassification error as illustrated in Rp) and the leaf nodes (Rl) as in (1) and (2), respectively. The parent node is converted to a leaf node if the risk-rate of the parent is less than the total risk-rate of its leaves (Rp < Rl), otherwise, the parent node is retained. The process is repeated for all parents of leaves until the tree is optimized. To clarify our notation, we illustrate the new method through a simple example. A simple decision tree example is given in After the decision tree is built, the proposed algorithm given in To compare the proposed PBMR method with two other post-pruning algorithms namely, Reduced-Error Pruning (REP) and Minimum-Error Pruning (MEP), five different datasets, Zoo, Iris, Diabetes, Labour, and Blogger have been utilized . Table 2Experiments are conducted by using java eclipse combined with Weka. It is known that attribute evaluator techniques can be applied to select the attributes that have the greatest impact on the dataset. Removing the worst ranked attributes that have lower importance on the dataset usually increases the accuracy of the algorithms . In thisAfter the worst attributes are removed with the attribute evaluators, the accuracies obtained by PBMR with 10-fold cross validation and by dividing the datasets into two sets as training and test are compared in Moreover, the time taken by each pruning method to prune the tree is also considered. The experiment is repeated 100 times on a personal computer running on Windows 7 (64 bits) operating system with 2.55 GHz Dual-Core CPU and 4 GB RAM. The average results of the experiments are presented in The next experiment includes the weighted average of precision and recall scores evaluations of the proposed method, REP, and MEP in The weighted averages of True Positive (TP) rate, False Positive (FP) rate and area under Receiver Operating Characteristic (ROC) curve are also considered to measure the performance of the pruning methods as in This paper introduces a new post-pruning method based on Bayes minimum risk. The efficiency of the proposed method in terms of attribute selection, accuracy, complexity, pruning time, precision score, recall score, TP rate, FP rate and area under ROC is compared to REP and MEP post-pruning methods by using five different datasets. The experimental results show that the proposed method produces better classification accuracy than REP and MEP in all test datasets while it does not create additional complexity than REP and MEP. The results also show that the proposed method yields satisfactory performance in terms of precision score, recall score, TP rate, FP rate and area under ROC compared to both REP and MEP approaches.The proposed algorithm adopts a post-pruning bottom-up method for C4.5 decision tree algorithm. As future works, the proposed PBMR method can be applied on C5.0 decision tree classifier and can be also modified for other tree base classifiers such as best first tree and random forest.


The tumor suppressor protein cylindromatosis (CYLD), as a microtubule-associated deubiquitinase, plays a pivotal role in a wide range of cellular activities, including innate immunity, cell division, and ciliogenesis. Structural characterization reveals a small zinc-binding B-box inserted within the ubiquitin specific protease (USP) domain of CYLD; however, the exact role for this module remains yet to be elucidated. Here we identify a critical role for the B-box in facilitating the intermolecular interaction and subcellular localization of CYLD. By co-immunoprecipitation assays we uncover that CYLD has the ability to form an intermolecular complex. Native gel electrophoresis analysis and pull down assays show that the USP domain of CYLD is essential for its intermolecular interaction. Further investigation reveals that deletion of the B-box from the USP domain disrupts the intermolecular interaction of CYLD. Importantly, although loss of the B-box has no obvious effect on the deubiquitinase activity of CYLD, it abolishes the USP domain-mediated retention of CYLD in the cytoplasm. Collectively, these data demonstrate an important role for the B-box module of CYLD in mediating its assembly and subcellular distribution, which might be related to the functions of CYLD in various biological processes. The tumor suppressor protein cylindromatosis (CYLD) is critically involved in the regulation of diverse signaling pathways, including nuclear factor-κB (NF-κB), transforming growth factor-β (TGF-β), and Wnt/β-catenin, through its deubiquitinase activity towards its substrates –4. It haglued, cytoplasmic linker protein 170 (CLIP-170), and the kinesin protein KIF13B [The CAP-GLY domains are conserved modules residing in many functionally diverse proteins, including the dynactin complex subunit p150n KIF13B , a key rn KIF13B . CYLD inn KIF13B . Given tRecent studies reveal that CLIP-170 and end-binding protein 1 (EB1), two important microtubule plus-end tracking proteins (+TIPs), can form dimer to exert their roles in the regulation of microtubule assembly , 20. IntIn cells, CYLD acts in concert with the +TIPs protein EB1 to regulate microtubule dynamics . Recent Both the CAP-GLY domain and USP domain have been shown to mediate protein-protein interactions. To define the molecular mechanism of which domain is responsible for CYLD intermolecular interaction, we constructed GST-tagged CYLD truncations Figure  and thenΔB-box (Δ786-837) plasmids  could not be detected in the precipitations  disrupted the retention of CYLD in the cytoplasm  had an elevated NF-κB-mediated reporter activity and overexpression of CYLD significantly suppressed the TNFR1-induced NF-κB activation Figure . Interesn Figure , suggestCYLD is an important deubiquitinase and microtubule-binding protein that involves multiple cellular activities, including cell cycle progression, innate immune responses, and cancer. Although the conserved CAP-GLY domains provide structural basis for the interactions of CYLD with microtubules and many other proteins, an interesting finding is that EB1 containing a known CAP-GLY domain-interacting motif interacts with the C-terminal USP domain of CYLD other than the CAP-GLY domains, implicating a previously unknown role for the USP domain in mediating protein-protein interactions. In this study, we find that the USP domain is critical for CYLD intermolecular interaction. Consistently, other studies reveal CYLD interacts with SPATA2 via the USP domain, supporting the notion that USP domain might also be a critical element for protein-protein interactions , 27.ΔB-box) completely abolishes its interaction with wild-type full-length CYLD  family proteins. Several studies suggest B-box module may act as a protein-interacting motif to mediate the recognition of TRIM proteins with their substrates , 28. In D Figure , suggestD Figure , which iOur further study demonstrates an essential role for the B-box module in retaining CYLD in the cytoplasm, which is consistent with observations reported by Komander et al. . HoweverΔB-box (Δ786-837) were generated by cloning the indicated cDNA into the pEGFPC1 vector.Antibodies against GFP, Flag, and GST were purchased from Sigma-Aldrich, and horseradish peroxidase-conjugated secondary antibodies were obtained from Amersham Biosciences. Glutathione (GSH) agarose beads and dual-Luciferase Reporter Assay System were from Promega. The mammalian expression plasmid for GST-CYLD, GST-CYLD 1-555), and GST-CYLD (556-953) were constructed by inserting the indicated cDNA into the pEBG vector. The mammalian expression plasmid for Flag-CYLD was obtained as previously described [55, and G2. Plasmids were transfected or co-transfected into cells with Lipofectamine 2000 (Invitrogen).HEK293T cells were cultured in the DMEM medium supplemented with 10% fetal bovine serum at 37°C in a humidified atmosphere with 5% COFor immunoblot analysis, proteins were separated by SDS-PAGE and transferred onto polyvinylidenedifluoride membranes (Millipore). Then the membranes were blocked with 5% fat-free milk, and probed sequentially with primary antibodies and horseradish peroxidase-conjugated secondary antibodies. Target proteins were visualized with enhanced chemiluminescence detection reagent (Pierce Biotechnology). For GST pull-down, cells transfected with GST-tagged plasmids were lyzed and cell lysates were incubated with glutathione-sepharose 4B beads at 4 °C overnight. The pulled-down proteins were then visualized by immunoblotting.Cell lysates were mixed with sample buffer  and loaded into the 10% native PAGE gel. The electrophoresis was carried out at 4 °C with a set of 15 voltage. Proteins in the gel were denatured with transfer buffer containing 2% SDS and were then transferred onto polyvinylidenedifluoride membranes and analyzed by immunoblotting.Cells grown on glass coverslips were transfected with GFP-tagged plasmids for 48 hours. Then cells were fixed with 4% paraformaldehyde at room temperature for 20 minutes. nuclei were stained with DAPI for 5 minutes. Coverslips were mounted with 90% glycerol in PBS and then examined with an Axio Observer A1 fluorescence microscope .ΔB-box plasmid. 48 hour later, cells were lyzed and the luciferase activity was measured using the FB12 luminometer (Berthold Detection Systems) and normalized to β-galactosidase activity.293T cells were co-transfected with the NF-κB luciferase reporter plasmid pGL4.32-NF-κB-Luc, β-galactosidase-expressing plasmid pcDNA3-LacZ, pcDNA3-Flag-TNFR1 plasmid, together with pEGFPC1-CYLD or pEGFPC1- GFP-CYLDAll the experiments were independently performed for three times, and analysis of statistical significance was determined by the ANOVA test for multiple comparisons.


The proximate composition, mineral composition, and sensory qualities of the recipes were determined using standard analytical procedures. The recipes had significantly (P < 0.05) higher contents of protein, fat, crude fiber, iron, zinc, sodium, and phosphorus compared with the control recipe (100% cocoyam flour). The protein content was highest in all recipes containing 50:50 cocoyam: cowpea flour . However, ikokore had higher iron (2.5 mg), phosphorus (92.5 mg), and zinc (1.92 mg) contents than ebiripo and ojojo. While the 80:20 recipe for ebiripo had significantly (P < 0.05) higher flavor and overall acceptability scores compared with other recipes. In conclusion, enrichment of cocoyam‐based recipes with cowpea flour improved the proximate composition, mineral composition, and sensory acceptability of the foods.The study was conducted to improve cocoyam‐based recipes (steamed cocoyam paste [ The dietetic value of cocoyam–cowpea blends is enormous in many hospitals, especially in Nigeria. Dieticians in Africa and other cocoyam‐consuming countries  will find the combination of cocoyam and cowpea highly valuable in the treatment of malnutrition and other chronic diseases that are caused by protein deficiency.Colocasia esculenta) is a well‐known food plant that has a long history of cultivation. Its corms are important sources of starch. Cultivars of two species Colocasia esculenta (taro) and Xanthosoma sagittifolium (tannia) are generally grown for food. It is consumed in homes, especially during periods preceding the yam harvest, which underscores its importance as a possible substitute for the crop , and as in almost all root crop proteins, sulfur‐containing amino acids are limiting. By contrast, cowpea protein is of higher value and can complement the deficiencies of cocoyam. Cowpea is popularly referred to as “beans” in Nigeria and it belongs to the group known as legumes. It is nutritious and provides protein, vitamins, and minerals. Cowpea grain contains about 25% protein  were prepared at the Food Preparation Laboratory of Nutrition and Dietetics Department, Federal University of Agriculture, Abeokuta, Nigeria.The cocoyam cormels and cowpea grains used in this study were purchased from Osiele and Kuto markets, Abeokuta, Ogun State, Nigeria. The food items . A deep spoon was used to drop the mixture into the hot oil, thereby forming ball shapes. The mixture was then deep fried in hot oil (about 170°C for 5 min) until light brown. The standardized recipe is shown in Table Cocoyam flour alone was used to prepare the control ts HETAN  for fryiThe composite flour  was weighed into a bowl and mixed with a small quantity of warm water to obtain a soft and smooth consistency. Salt, ground pepper, and onion were added to taste before thoroughly mixing. A small quantity of palm oil was poured into the pot (to prevent it from burning), cent leaves were washed and used as base, and then smoked fish was put on top of the base. The cocoyam–cowpea paste was added in small even sizes on the smoked fish. Another small quantity of warm water was added to improve consistency and allowed to boil for 10 min. The dried fish and remaining oil were added, allowed to cook for 20 min, and then it was stirred and ready to be served. The standardized recipe is presented in Table The ground ingredients  were added to the cocoyam–cowpea composite flour. Palm oil with warm water was added to make a slurry of soft and smooth consistency. Salt was added to taste. The mixture was wrapped in local leaves and then steam cooked for about 30 min. The standardized recipe for steamed cocoyam paste preparation is shown in Table The moisture, fat, protein, ash, and crude fiber contents were determined using Association of Official Analytical Chemists AOAC  methods.The mineral content in each sample was analyzed using atomic absorption spectrophotometer (AAS) fitted with a hollow cathode lamp and a fuel‐rich flame (air‐acetylene) following the AOAC  procedur; Ukpabi The sensory evaluation of the products was performed using a 9‐point hedonic scale ranking 0–8 (0 = extremely dislike and 8 = extremely like). The panelists assessed the product for flavor, fluffiness, color, taste, and overall acceptability (Iwe P < 0.05). Statistical analysis was done using Statistical Package for Social Science (SPSS) version 16.0 .Data were analyzed using analysis of variance (ANOVA) and Duncan multiple range test to test significant differences between means . The mean ash content value for ojojo was 2.1%. The crude fiber contents were 2.35% for 100% cocoyam, 2.74% for 80:20, 2.75% for 70:30, 2.84% for 60:40, and 2.91% for 50:50. The carbohydrate values of ojojo were 28.51% for 100% cocoyam, 25.23% for 80:20, 26.28% for 70:30, 18.54% for 60:40, and 25.42% for 50:50.The moisture content values for ikokore were 54.86%, 59.47%, 64.28%, 62.36%, and 63.39% for 100% cocoyam, 80:20, 70:30, 60:40, and 50:50 blends, respectively. The ikokore from 50:50 composite flour recorded the highest protein (10.56%), fat (10.06%), and ash (3.08%) contents. The carbohydrate content was highest for 100% cocoyam flour (30.09%), and decreased with increasing addition of cowpea flour.The mean moisture contents of ebiripo was highest in 100% cocoyam (58.38%). The ebiripo from 50:50 composite had the highest values for protein (10.36%), fat (12.71%), ash (2.88%), and crude fiber (2.88%), whereas carbohydrate was highest in 100% cocoyam sample. Ebiripo had the highest moisture content followed by ikokore and ojojo, respectively.The mean moisture content of ojojo had the lowest percentage of protein (2.41%) when compared with the control samples of ikokore and ebiripo, which had protein contents of 3.5% and 2.83%, respectively. Samples of the recipes developed with 50% cowpea flour substitution were significantly higher (P < 0.05) in protein  than the samples with >40% cowpea flour substitution. The percentage fat content of all the developed recipes differ significantly (P < 0.05), except the cowpea flour substitution of 40% and 50% for ikokore. The fat content increased with the increase in cowpea flour. The fiber content of the products ranged from 2.32% to 3.08%. The 50% cowpea flour substitution of ikokore was significantly higher in crude fiber (3.08%) at P < 0.05, whereas the ebiripo control sample had the lowest crude fiber percentage (2.32%). The percentage ash contents were greatest in all the 50% cowpea flour‐substituted recipes , although ikokore had the highest percentage ash content of 3.20% when compared with ojojo and ebiripo with 2.8% and 2.88%, respectively. The carbohydrate content decreased (from 30.09% to 12.77%) with an increase in the percentage (from 20% to 50%) of cowpea flour. There was no significant difference (P > 0.05) in the carbohydrate contents of the ebiripo samples. However, the percentage carbohydrate content of ojojo and ikokore samples differs significantly above 20% addition of cowpea flour (P < 0.05).The protein content of cocoyam was 1.5%, which is low compared with the protein content of 23.0% in cowpea. The protein content of the recipes developed in this study increased as the percentage of cowpea flour increased. The control sample of The results of mineral composition of the recipes developed are shown in Tables ikokore had the highest value of iron, ranging from 0.91 to 2.5 mg/100 g, compared with ojojo with 0.70–1.30 mg/100 g and ebiripo with 0.77–1.30 mg/100 g. Ikokore had the highest value of phosphorous, ranging from 63.40 to 92.50 mg/100 g, compared with ojojo with values of 59.83–91.50 mg/100 g and ebiripo with values of 59.83–85.2 mg/100 g. Ikokore recorded the highest value of zinc, ranging from 0.44 to 1.92 mg/100 g, whereas ojojo had values of 0.40–1.17 mg/100 g and ebiripo had values of 0.37–1.55 mg/100 g.For 0–50% cowpea flour inclusion, ojojo, ikokore, and ebiripo decreased with increasing cowpea flour inclusion. The calcium content of ojojo ranged from 51.7 to 35.50 mg/100 g, while ebiripo followed with values of 56.30–39.53 mg/100 g, and ikokore was the lowest with values of 54.43–32.85 mg/100 g. For potassium, ikokore had the least decrease of 1125.50–897.33 mg/100 g, followed by ebiripo with values of 1045.30–810.50 mg/100 g, and ojojo had the lowest value of 1113.80–795.50 mg/100 g.It was observed from the table of results that the values of calcium and potassium in all the control recipes (100% cocoyam flour) of ojojo, the control sample had the most acceptable color with a mean value of 6.44, whereas samples with 20% and 50% cowpea flour substitution had the least acceptable color with a mean value of 5.96. Also, samples of ojojo with 40% cowpea flour substitution had the most acceptable flavor with a mean value of 6.28, while the sample with the least acceptable flavor was 30% cowpea flour substitution with a mean value of 5.80. The 20% cowpea flour substitution had the most acceptable fluffiness with a mean value of 6.32, whereas the sample with 50% cowpea flour substitution had the least acceptable fluffiness with a mean value of 5.68. Lastly, the sample with 40% cowpea flour substitution had the highest taste acceptability with a mean value of 6.48, while the sample with 50% cowpea flour substitution had the least with a mean value of 5.72. In summary, samples of ojojo with 40% cowpea flour substitution had the highest mean value of overall acceptability of 6.64, whereas samples with 20% and 50% had the least overall acceptability with a mean value of 5.80.The results of the sensory evaluation of the cocoyam–cowpea composite flour recipes are shown in Tables ikokore, the sample with 40% cowpea flour substitution had the most acceptable color, flavor, fluffiness, and taste with mean values of 6.92, 6.56, 6.56, and 6.68, respectively. The control sample (100% cocoyam) had the least acceptable color, flavor, fluffiness, and taste with mean values of 5.32, 5.48, 5.56, and 5.36, respectively. In summary, samples of ikokore with 40% and 30% cowpea flour substitution had the highest mean value of overall acceptability of 6.52, whereas the control sample (100% cocoyam) had the least mean value of overall acceptability of 5.20.For ebiripo, the control sample had the highest acceptability for color, flavor, fluffiness, and taste, with mean values of 7.48, 7.24, 7.48, and 7.88, respectively. Samples with 50% cowpea flour substitution had the least acceptability for color, flavor, and fluffiness with mean values of 5.20, 5.52, and 5.04, respectively. Samples with 30% cowpea flour substitution had the least acceptability for taste with a mean value of 6.16. In summary, the samples with 20% cowpea flour substitution had the most overall acceptability with a mean value of 7.52, whereas samples with 40% cowpea flour substitution had the least overall acceptability with a mean value of 5.84.For ojojo, ikokore, and ebiripo). This expected increase in the protein of the blends is the basis for the enrichment such that the final product will have higher protein quantity and quality. Because tuber crops including cocoyam are low in sulfur amino acids  had the most acceptable color for all the products. However, the sample with 40% cowpea flour substitution was most acceptable in terms of flavor, taste, and overall acceptability. This result also could be attributed to the bean flavor of cowpea. The sample with 20% cowpea flour substitution had the most acceptable texture (fluffiness).This study has shown that significant improvement in the proximate composition, mineral composition, and sensory acceptability is achievable through enrichment of cocoyam flour‐based recipes with cowpea flour.None declared.


The BAR domain is the eponymous domain of the “BAR-domain protein superfamily”, a large and diverse set of mostly multi-domain proteins that play eminent roles at the membrane cytoskeleton interface. BAR domain homodimers are the functional units that peripherally associate with lipid membranes and are involved in membrane sculpting activities. Differences in their intrinsic curvatures and lipid-binding properties account for a large variety in membrane modulating properties. Membrane activities of BAR domains are further modified and regulated by intramolecular or inter-subunit domains, by intermolecular protein interactions, and by posttranslational modifications. Rather than providing detailed cell biological information on single members of this superfamily, this review focuses on biochemical, biophysical, and structural aspects and on recent findings that paradigmatically promote our understanding of processes driven and modulated by BAR domains. Identification of sequence homology between the N-terminal regions of the Bin, the amphiphysin, and the yeast Rvs proteins led to the recognition of a novel protein domain which was named “BAR domain” as an acronym composed of the first letters of these proteins . This doMost BAR domain proteins contain one or several additional domains with lipid-binding, protein-binding and/or enzymatic activities Figs. b, 2. TheIn this review, we focus on the association of the BAR-domain dimer with intramolecular or intradimer domains as well as on its ligand-binding characteristics. Rather than giving a broad overview on the functional diversity of BAR domain proteins, we here specifically present those studies that further our mechanistic understanding of processes driven/modulated by BAR domain dimers.The excess of positively charged residues at the concave side of the crescent-shaped dimer is a hallmark of N- and F-BAR domain proteins and is suggestive for their preferential binding to membrane regions rich in anionic phospholipids , 26. InsUsing liposomes composed of 80% phosphatidylcholine (PC) and 20% phosphatidylethanolamine (PE) as non-binding control, it was found that replacement of 10% PC by the negatively charged phosphatidylserine (PS) greatly enhanced binding of the F-BAR domain proteins FBP17 and pacsin (syndapin) . LiposomComparing the requirements of membrane association within the srGAP subfamily of F-BAR proteins, Coutinho-Budd et al. found that srGAP2 and srGAP3 differently depend on PIP2 for membrane association . In contStudying the two F-BAR proteins CIP4 and nostrin that cooperate in the regulation of epithelial morphogenesis, Zobel et al.  found th2, Hof1p, and Bzz1p binding was indifferent or even negatively affected by PIP2, respectively. Moreover, PS-containing and pure PC liposomes were equally efficient in binding Hof1p and Bzz1p proteins, suggesting that negatively charged lipids are not essential for membrane association . In agreement with PIP2-enhanced binding to liposomes, structural analysis of the Rgd1p F-BAR domain identified a cluster of five positively charged residues at the concave side, coordinating an inositol-hexa-phosphate molecule . The evolutionary conserved residues 201–213 that precede the YN domain form an amphipathic helix upon membrane binding and are essential for the tubulating activity of the PX-BAR superdomain. Thereby, this arrangement is functionally similar to the amphipathic helix in N-BAR domain proteins. Liposome-binding studies revealed that the binding of the PX-BAR protein was independent of the liposome size in the presence of phosphoinositides, suggesting a strong tubulating capacity. Conversely, when phosphoinositide-free liposomes were used, the PX-BAR domain only bound to liposomes smaller than 100 nm, indicating a clear curvature-sensing effect [0 amphipathic helix that induces membrane curvature; and (4) lateral oligomerization of PX-BAR domains to promote tubule formation. Further studies will be necessary to elucidate the molecular details of the role of SNX9 in endocytosis where SNX9 proteins are likely recruited to clathrin-coated membrane buds via PIPs and then exert their tubulating activity to generate the narrow neck prior to the final dynamin-dependent vesicle scission event.The sorting nexins (SNX) form a subfamily of N-BAR domain proteins that are known to interact with endosomal components and play a role in endocytosis. The BAR domain is located at the C-terminal end of the protein and is preceded by a PX domain that is known to specifically bind to phosphoinositides Fig. . SNX9, Sg effect . Interesg effect . Moreoveg effect : (1) seqThe scaffold protein PICK1, which consists of a PDZ domain, a central BAR domain, and a C-terminal ACT domain, is predominantly expressed in neuronal cells and has been recognized in trafficking of important neuronal proteins. PDZ domains are interaction modules implicated in binding short motifs at the C-termini of target proteins . Two conMadasu et al., who circumvented the aggregation by recombinantly fusing the human PICK1 to the C-terminus of the maltose-binding protein (MBP), used SAXS to analyze the full length PICK1 molecule . ModelinLKV) in which the last three amino acids of PICK1 (413CDS415) were replaced by the specific sequence LKV that binds in the pocket of the PDZ domain, alleviating to some extent the aggregation issue [Karlsen et al., on the other hand, generated a mutant  of about 60 amino acids. Secondary structure analyses predict that ACT is mainly disordered and modeling of the SAXS data indicates that it protrudes from the PDZ-BAR surface of the second subunit of the PICK1 dimer . The fun0, which is thought to be unstructured in solution and only becomes helical when the molecule is in contact with the membrane. The role of the interdomain interaction between the SH3 and the BAR domain was suggested to be the stabilization of the H0 helix in solution [0/SH3 complex is separated in positively and negatively charged regions with the positively charged residues of the amphiphilic helix located at the same side as the concave membrane-binding side of the BAR domain. The H0/SH3 complex formation was corroborated by kinetic studies of endophilin dimer dissociation where mutants lacking either the H0 helix or the SH3 domain revealed significantly faster dissociation kinetics than the full length protein [0 helix of the juxtaposed subunit of the dimer. Thus, the interaction between the SH3 domain and the H0 helix implies a dual auto-regulation of the endophilin: the H0 helix and the SH3 domain are both inhibited from membrane binding and association with SH3 binding partners, respectively. In line with this model, Meinecke et al. showed that membrane association of endophilin and amphiphysin, another N-BAR and SH3 domain-containing protein, was dependent on the presence of SH3-binding partner dynamin, a GTPase essential for vesicle scission [Endophilin is one of the BAR domain proteins that play a central role in endocytosis. It is composed of an N-BAR and a C-terminal SH3 domain, a domain typically binding to proline-rich peptides of respective binding partners Fig. . SAXS ansolution  by prote protein . The datscission . This auscission .A similar auto-regulatory property was described for the F-BAR domain protein syndapin1/pacsin-1 . The strThe Ras superfamily is a class of small GTPases that act as molecular switches in a wide variety of cellular functions. Interestingly, the BAR domain protein arfaptin was shown to interact with several members of this large protein family, namely with Rac1, thereby being involved in membrane ruffling at the plasma membrane, as well as with GTP-bound ADP ribosylation factor (Arf) proteins and the Arf-like protein Arl1, implicating a regulatory function at the Golgi complex –92. TarrStudying the complex regulation of membrane ruffling Miki et al. identified IRSp53 as a novel Rac-binding protein . Using pRac was also found to bind to MIM-B, another I-BAR domain protein with a regulatory role in cytoskeleton-based processes , again sThe APPL proteins contain a BAR-PH domain module and a C-terminal phosphotyrosine-binding domain (PTB) and are known Rab effectors functioning in nuclear signal transduction Figs. b, 2. MiaAnother interesting functional link between the superfamilies of BAR domain proteins and small Ras-like GTPases was found by Boulakirba et al. reporting the direct association of EFA6A (the Arf6-specific exchange factor) and endophilin . Using tA tight spatial and temporal coordination of actin polymerization and plasma membrane remodeling is a characteristic feature of many cellular processes, including endocytosis, exocytosis, cell motility, and intracellular trafficking. In these processes, BAR domain-containing proteins emerged as key regulators linking signaling pathways to actin cytoskeleton and membrane dynamics. To regulate actin dynamics, several members of BAR domain family directly bind to actin, or to actin-associated and regulating proteins via distinct domains. In this respect, BAR domain proteins were shown to bind to both monomeric (G-actin) as well as filamentous (F-actin) actin. While binding to G-actin is mediated through specialized G-actin-binding domains , F-actin binding was shown to be mediated directly through their BAR domains. Until now, binding to F-actin was demonstrated for six BAR domain proteins, namely Gas7, PICK1, MAYP/PSTPIP2, pacsin-2, MIM, and IRSp53 , 104–106Indeed, PICK1 was initially found to bind to F-actin and the Arp2/3 complex and thus to inhibit Arp2/3-mediated actin assembly activated by the N-WASP VCA domain, which is important for morphology of neurons and endocytosis stimulated by AMPA receptor . In a reSimilarly, earlier studies demonstrated that I-BAR domain of MIM binds and bundles actin filaments, interacts with the small GTPase Rac, and thus, it is important for MIM filopodia-forming activity . Later oThe situation might be more complex for IRSp53, which possesses an N-terminal I-BAR domain structurally, sequence wise and functionally related to the I-BAR domain of MIM as well as a C-terminally located WH2 domain Fig. , and thuThe same is true for Gas7, the over-expression of which leads to changes in microfilament organization. Gas7 co-localizes with F-actin in membrane ruffles and was found to interact and cross-link actin filaments in vitro via the C-terminal BAR domain . HoweverThis, however, is not the case for PSTPIP2, which was found to associate with actin in macrophages . In vitrA general issue with the binding of BAR domains to F-actin can be seen in the fact that the interaction with F-actin and membrane lipids seems to be mutually exclusive. The affinity of the F-BAR domain of pacsin-2 is higher for membrane lipids than for F-actin, a finding that is likely also true for other F-actin-binding BAR domains . Thus, iIn our recent study, we compared several BAR domains  with respect to their actin-binding properties in vitro . InteresIn 2011, two papers independently reported a role for the F-BAR domain protein pacsin-2 in caveolar biogenesis , 13. SenPolycystin-1 (PC1) is a large integral membrane protein involved in tubule formation in the major organs of our body and is associated with polycystic kidney disease (PKD), the most common life-threatening genetic disease. Yao et al. reported the interaction of the intracellular C-terminal domain (ICD) (residues 4079–4302) of PC1 with of pacsin-2 . The pacXenopus laevis [The interaction between pacsin-2 and filamin A (FlnA), a cytoskeletal and scaffold protein, was first identified by Nikki et al. implicating a role for this complex in regulation of cytoskeletal processes at focal adhesions . This cos laevis , 120. Res laevis . FlnA iss laevis . A potens laevis . This mos laevis . An atyps laevis . InteresThe F-BAR domain protein PSTPIP1  was independently identified in two-hybrid screens as an interactor of the PEST-type protein tyrosine phosphatase (PEST PTP)  and as iAgain by a two-hybrid screen, PSTPIP1 was found to interact with pyrin, a protein mutated in a systemic auto-inflammatory disease called familial Mediterranean fever (FMF) . The B bSchizosaccharomyces pombe, cytokinesis and the assembly of the cytokinetic actin ring is critically dependent on the F-BAR domain protein CDC15 [In in CDC15 . Assemblin CDC15 . The binin CDC15 . It has 0 helix by Rho kinase has been observed during clathrin-mediated endocytosis of the EGF receptor. Expression of a phosphomimetic mutant T14D inhibited the internalization of the EGF receptor, whereas endophilin wild-type or a T14A mutant did not [0 helix is also a site of auto-regulation [Phosphorylation of endophilin A1 on T14 in the N-terminal amphipathic H did not . In an egulation , the T14Drosophila [A further phosphosites of endophilin A1, S75, plays an important role in clathrin-mediated endocytosis of synaptic vesicles and subsequent neurotransmission at the synapse in osophila . S75 is osophila  Fig. 6)Drosophilosophila .2 in the central 6 helix bundle region of the F-BAR domain dimer, and T181 at helix H4 at the distal tip of the dimer. These residues are also conserved and located at the same structural position in other F-BAR proteins, Cip4, FBP17, and FCHO2, suggesting a more general importance of these phosphosites for the regulation of F-BAR domain activity. Modeling analyses suggest that these phosphosites affect the F-BAR function by different mechanisms: S76 phosphorylation may alter the curvature of the F-BAR dimer, whereas T181 phosphorylation may interfere with tip-to-tip inter-dimer association necessary for filament assembly. In fact, both phosphomimetic mutants showed altered liposome-binding and tubulation activity in vitro, however, with different specificities. Intracellular tubulation upon over-expression was absent in the T181E mutant and significantly reduced in S76E mutants as compared to wild-type pacsin 1. The phosphomimetic mutants did not affect bulk endocytosis, but especially T181E was found to be developmentally regulated and did affect neuromorphogenesis and neurite outgrowth. The kinase and signaling pathway that are responsible for these phosphorylations have yet to be explored and this will be essential to fully evaluate the cell biological importance of this posttranslational modification.Pacsin 1 (syndapin I) interacts with dynamin 1 in nerve terminals and is thereby involved in activity-dependent but clathrin-independent bulk endocytosis , 136. ItGehart et al. identified an essential step in the regulatory mechanism of secretory granule biogenesis at the trans-Golgi network (TGN), a process which is thought to be critically impaired in pancreatic β cells of type II diabetic patients . They foAn Akt-dependent phosphorylation of S260 of arfaptin-2 was shown to inhibit toxicity induced by polyQ-huntingtin indicating a neuroprotective effect of this posttranslational modification within the BAR domain. In line with this is the finding that arfaptin-2 is upregulated in Huntinton disease patients. While the involved molecular mechanism is still unclear, a rescue of impaired proteasome activity was found as a downstream effect of this phosphorylation event .During the last decade, it became clear that BAR domain proteins are key players in membrane shaping processes. Each member of the BAR domain superfamily—more than 70 are by now characterized only in humans—appears to be involved in the formation of certain subcellular membrane structures. This is achieved by its specific BAR domain architecture mostly in combination with a unique set of additional domains with enzymatic, signaling, protein, or lipid-binding properties. These domains are involved in the regulated assembly of macromolecular membrane complexes and modulate the membrane sculpting activity of the BAR domain dimer. Some membrane processes involve several BAR domain proteins in a concerted manner and/or in a consecutive order. The molecular mechanisms that coordinate such processes in space and time are only slowly emerging. Innovative methods like BioID, a biotin ligase-based tagging proteomics to identify proximal partners of BAR domain proteins (at the membrane), or CRISPR/Cas9 applications that knockout/modify not only single but several BAR domains at the same time will help to unravel the molecular network behind cellular membrane morphogenesis. These efforts will also shed light on aberrations of these processes in pathological situations and will help to understand the involvement of BAR domain proteins in various disease-related disorders.