An improved mathematical model used to study the coupling characteristic of the multi-span transmission lines is developed. Based on the solution method for single-span cable, an expression for the dynamic stiffness of two-span transmission lines with an arbitrary inclination angle is formulated. The continuity of displacements and forces at a suspension point is used to derive the dynamic stiffness. Interactions between insulator strings and adjacent spans are accommodated. Considering the infinite dynamic stiffness corresponds to the natural frequencies of the transmission lines, the finite-element method (FEM) is employed to assess the validity of the dynamic stiffness. In the numerical investigation, attention is focused on the effect of the inclination angles, Irvine parameter, insulator string length and damping parameter. In addition, the modal function corresponding to the natural frequencies is derived. Then, the results of comprehensive parametric studies are presented and discussed. Special attention is paid to the effect of the Irvine parameter and damping parameter on the in-plane modal shapes. Finally, according to the theoretical model of two-span transmission lines, the generalized dynamic stiffness of transmission lines with an arbitrary number of spans and inclination angles is derived. The method can be used as the basis of the vibration analysis on a wide variety of multi-span transmission lines. Galloping is associated with the high amplitude and additional tension in the cable, which can lead to damage to the electrical power network, such as short circuiting, failure of sub-conductors and spacers, and even the collapse of towers ,2. Figuret al. :ectively . u2(0), Taking into account the continuity conditions of displacements, the displacements at point B are obtained byw1 of the first span consists of two parts, the first part is rigid rotation displacement and the second part represents the displacement induced by conductor deformation. The displacement w2 of the second span is similar to that of the first span. w1 and w2 are given bytw1 and tw2 represent the displacements induced by the conductor deformation. Substituting equation  and equation (2.1) into equation , we obtainThe displacement θ of insulator string to be small, the moment equation of the insulator string around the suspension point O is obtained asJ is insulator string moment of inertia, W and a are insulator string mass and length, respectively. The vertical forces FV1 and FV2 exerted by the first and second spans at B, respectively, are shown in FV1 and FV2 are given byInsulator string is an important part of transmission lines and plays an important role in electrical insulation and mechanical support. Owing to the swing of insulator string, the kinetic energies of any span may be transferred to adjacent spans. So, it is necessary to consider the effect of the insulator string on the dynamic motion of transmission lines. Assuming the swing angle Limiting now the discussion to transmission lines with small sags and low-amplitude motions, the component of the tension directed along the axis normal to the chord joining the support points is given byThe horizontal components of the forces acting at the lower point of insulator string as shown in A point in two-span transmission lines is subjected to a harmonic force, the increment displacements and additional tensions are given byWhen a–c), equation  becomesζ ≤ 1, Using equation , with the given boundary conditions of equation , are obtained bya,b) represents the modal shape of two-span transmission lines. However, in equation , there are some unknown parameters to be solved. Substituting equations , , (2.13) and  into equation , the tension increments are given byThe solutions of equation (2.15a–c) into equation (2.12), Substituting equation  and (2.14a–c) into equation (2.13), the horizontal components of the forces acting at B, Substituting equations (2.19a–c) into equation (2.10), combining the equilibrium equation at point A, we obtainB2 isKd, is the ratio of the applied force to the corresponding displacement. From equations (2.22) and (2.23), the dynamic stiffness function could be given by the expressionKd, depends on geometrical parameters, materials and excitation frequency. Upon carrying out the limiting transition ω → 0, equation (2.21a–d) reduces toKd can be obtained. The dimensionless frequency Substituting equations (2.20) and , in which the parameter H is obtained by iteration solution of equation (2.28) after setting L1 equal to L10. It is noted that H of the natural configuration may be understood as the parameter without the original physical definition, and the catenary curve is not the unique choice of the natural configuration of the first span. The static configuration is calculated by means of ABAQUS after application of gravity. Natural configurations of other spans can be obtained in the same way as the natural configuration of the first span.The controlled parameter of actual transmission lines under self-weight, −1, Young's modulus E is 7.0 × 104 MPa, and the dimension of the conductor is 27.63 × 10−3 m. The suspension insulator string consists of 28 ball-and-socket porcelain insulators of model XP-16 with self-weight 6.0 kg, the length of the suspension insulator string is 6.47 m, and its Young's modulus is set to be 200 GPa. Twenty-eight truss elements are used to simulate the suspension insulator string. The horizontal tension of a span in the static configuration under self-weight is usually known and is 14.25 kN(λ1 = 3π). According to the known horizontal tension in the static configuration and iteration solution of equation (2.28), the horizontal tensions used to determine the natural configuration are obtained, 16.69 kN of the first span and 17.47 kN of the second span. The static configuration is calculated by mean of ABAQUS under self-weight from the natural configuration, as shown in The model of the typical transmission line section, which consists of two-span conductors and suspension insulator, is established to calculate the dynamic stiffness. The distances between the supports of the first and second spans are 200 m and 180 m, respectively. The inclination angles of first and second spans are the same as 10°. The conductor type is aluminium conductor steel reinforced cable LGJ-400/50, mass per unit length is 1.511 kg mKd, with respect to the excited frequency is obtained. The dynamic stiffness is normalized with respect to the corresponding static stiffness value to calculate the ordinates, as shown in Ks is the static stiffness. The static stiffness may be obtained from equation (2.24) by letting ω = 0. The increment of the horizontal coordinate in the dynamic stiffness curve is 0.0005. The resonant peaks of the curves of the dynamic stiffness correspond to the dimensionless natural frequency of two-span transmission lines supported at both ends. The abscissa values corresponding to the first four peaks, which are, respectively, 1.063, 2.000, 2.222 and 2.595, are very close to the dimensionless natural frequencies obtained by ABAQUS. The comparison of natural frequencies obtained by two methods shows that the theoretical formula for dynamic stiffness is reasonable. With the dynamic stiffness curves in Substituting the parameters of the previous example into equation (2.24), the dynamic stiffness, 2.3.1/π = 3 and λ1/π = 7 is studied, respectively. When λ1 is 3π, the dynamic stiffness with different insulator string lengths is depicted in figure 5a. Compared with the results corresponding to other insulator strings, the value of the dimensionless natural frequency significantly decreases with increasing the insulator length from 1 to 3 m. It is shown that when insulator length is small, the effects of insulator string length on the natural frequency are all the more obvious. When λ1 is 7π, the dynamic stiffness with different string lengths is represented in figure 5b. The peak value on the dynamic stiffness curve decreases with increasing the insulator string length. The results also show that the natural frequency is more sensitive to the insulator string length when the insulator string length is small. The comparison of the two figures shows that the natural frequency of two-span transmission lines with λ1 = 7π is more sensitive to the insulator string length than that of two-span transmission lines with λ1 = 3π.Insulator string is an important part of transmission lines and plays an important role in electrical insulation and mechanical support. The length of the insulator string depends on the voltage in transmission line design. In fact, the change in insulator string length will also have some effect on the mechanical characteristics of multi-span transmission lines. Therefore, the sensitivity of dynamic stiffness and natural frequency to insulator string length is investigated in the following. The same material parameters as the previous example are used. The span length of two-span transmission lines is 200–180 m. Increasing the insulator string length from 1 m to 50 m, the dynamic stiffness of two-span transmission lines with λ1/π = 7. It can be seen that the dimensionless natural frequency decreases with increasing the insulator string length. The effect of the insulator string length on the natural frequency is greater when λ1/π = 7 than that when λ1/π = 3. In 2.4.The inclination angle of transmission lines depends on the terrain. In order not to significantly increase the weight and top size of a transmission tower, the design inclination angle is generally small. Therefore, the transmission lines with the range of inclination angle as −30° ∼ 30° are used in this paper. Also, for convenience comparison, the inclination angle of the first span remains a constant value of 20° when the inclination angle of the second span is changed.1 is 7π. β2. As a result, the peak values of the dynamic stiffness depend on the inclination angle. The natural frequency, which is identified by the peak of the dynamic stiffness, decreases with the increasing inclination angle of the second span.Let the span distances of first and second spans be 200 and 180 m, and λ1 of 7π. The inclination angle β1 is set to be 0° ∼ 30°, and β2 is set to be −30° ∼ 30°. Tables 1β1 is a constant.In order to further verify the correctness of the dynamic stiffness theory, the ABAQUS software is used to establish an FEM model of two-span transmission lines with the span length of 200–180 m and λ1/π, the scatter plots are the natural frequencies identified by the peak of the dynamic stiffness. The results show that the in-plane natural frequencies calculated by the dynamic stiffness theory coincide well with the results obtained by the ABAQUS.Assume the span lengths of two-span are 200 and 180 m, the inclination angles of the first and second spans are equal to 20°. In 1/π. As can be seen from equation (2.24), the first natural frequency is close to 1 when the tension of the conductor gradually increases. The modal shape corresponding to the first curve is shown in figure 9a. Figure 9a shows that the mode displacement is zero over the entire second span length when λ1/π = 0.1. The swing angle of the insulator string gradually decreases with increasing the tension of the conductor. The insulator string has the largest swing angle when λ1/π = 10. The phenomenon reveals that the effect between two spans in the first modal shape of two-span transmission lines decreases with increasing the horizontal tension.In 1/π. When the second natural frequency comes increasingly closer to the third natural frequency, there is a transition region where the two frequencies are close to each other but distinct as shown in subgraph 1 of figure 9b. The transition of modal shapes happens gradually as the geometrical parameter λ1/π from 1.8 to 2. The mixture shape of the hybrid mode is mainly confined to the first span. When the geometrical parameter λ1/π is larger than 2, the second natural frequency is independent of the λ1/π, and it is approximately at a constant of 2. Based on a single-span inclined cable, the transition region and hybrid modes have been studied by Triantafullou   1/π. Whe1/π is in the range of 2 ∼ 2.2, the third natural frequency curve increases with increasing λ1/π. When the third natural frequency comes increasingly closer to the fourth natural frequency, there is the second transition region where the two frequencies are close to each other but distinct as shown in subgraph 2 of figure 9c gradually transforms into an antisymmetrical mode when the geometrical parameter λ1/π increases from 2.2 to 2.4. When the geometrical parameter λ1/π increases from 2.2 to 2.4 in the second transition region, the antisymmetrical mode, which corresponds to the fourth natural frequency, changes into hybrid mode. Then this hybrid mode as shown in figure 9d gradually changes into the symmetrical mode. The shape of the hybrid mode is mainly confined to the second span. The results demonstrate that the dynamic stiffness of two-span transmission lines, in which a span is attached at different heights, offers a simple yet accurate means of expressing the natural frequency.In 2.5.a,b). It can be seen that the modal shape is asymmetrical. This is because the displacements at both ends of a span are not zero. i = 1,2,3, … , signify the first, second, third, etc. symmetrical in-plan modes, respectively. The modal function is normalized with respect to iD. iD is the maximum absolute value of modal displacement. The antisymmetrical mode is given byi = 1,2,3, … , signify the first, second, third, etc. antisymmetrical in-plan modes, respectively. The equation  is valid when π.The modal shape is calculated by equation , the FEM model of two-span transmission lines, in which the span lengths are 200–180 m and the inclination angles are −20° to −20°, have been established in ABAQUS. Considering the restrictions regarding the application of the theoretical formulae, the geometrical parameter λ1/π is set to 2.5. At the outside of the transition region, all modes exhibit the approximate symmetrical or antisymmetrical modal shape in a span. As presented in figure 10a, the solid lines are the first two symmetrical modes calculated by ABAQUS, and the scatter plots are calculated by equation (2.30). The first symmetrical mode calculated by equation (2.30) coincides well with the FEM result obtained by ABAQUS. As shown in figure 10b, the first antisymmetrical modes calculated by Equation (2.31b) and ABAQUS are in good agreement. For the second symmetrical mode and the second antisymmetrical mode, the modal shape calculated by the analytic solution is different from that calculated by ABAQUS, as shown in 1/π. The errors between the two modal shapes calculated by the theoretical expression and ABAQUS decrease.In order to verify the simplified modes presented in equations (2.30) and , it can be seen that when λ1/π is close to 2.3, the natural frequencies corresponding to the third and fourth modes are close to 2π. When the two natural frequencies are close to each other, the symmetrical mode calculated by equation (2.30) and the antisymmetrical mode calculated by equation  are orthogonal. Therefore, according to the linear superposition principle, the hybrid modes are given by the symmetrical mode and the antisymmetrical mode asm = 1,2, signifies the span number.From 1/π is changed gradually. The hybrid modes of the two-span with the geometrical parameter λ1/π = 2.4, λ1/π = 2.3 and λ1/π = 2.25 are calculated, respectively, by equation (2.32) and the FEM. As shown in π, which means that it is reasonable to use the equation (2.32) to describe the hybrid modal shape. In In order to verify the applicability of equation (2.32), in the following analysis, the span lengths (200–180 m) and the inclination angles (20°–20°) are fixed and the geometrical parameter λ2.6.a,b) may be written in the formξ1 and ξ2 are defined. ξ1 and ξ2 are the damping parameters of the first and second spans, respectively. In transmission lines, internal damping mainly comes from the conductor cables. When a dynamic load is applied to a conductor, the internal damping arises from axial friction between the strands. As a matter of act, it is difficult to accurately determine the damping ratio of the conductor. Different values of viscous damping ratios in the range of 0.08 ∼ 4.0% for vertical movement are used in the numerical study [In the previous section, only the modal shapes and natural frequencies were discussed. In many cases, the influence of damping upon the response of a vibratory system is minor and can be disregarded. In general, since the effects are not known in advance, damping must be considered in the vibration analysis of any system . In ordeal study ,41,45.1/π is set to 2.5. Next, the effect of the dimensionless factor ξ1 on dynamic stiffness was studied. Figure 12a shows the real part of dynamic stiffness, and figure 12b shows the corresponding imaginary part of dynamic stiffness. As would be expected, damping significantly affects the dynamic stiffness only at excited frequencies close to the natural frequencies of two-span transmission lines.In order to study the effects of damping on the modal shape and natural frequency, the model of two-span transmission lines, in which the span lengths are 200–180 m and the inclination angles are 20°–20°, have been established. The geometrical parameter λa shows the real and imaginary components of the first complex mode. It is shown that the damping parameter significantly affects the shape of the real component of the first complex mode when the value of the damping parameter is large. It is important to note that the shape of the real component of the first complex mode is different from the shape of the imaginary component. Figure 13b shows the real and imaginary components of the second complex mode. It is shown that the damping parameter does not significantly affect the shape of the real component of the second complex mode. The shape of the real component of the second complex mode is close to that of the imaginary component. Figure 13c shows the real and imaginary components of the first antisymmetrical mode. The damping parameter does not alter the shape of the real component of the first antisymmetrical mode. In addition, the shape of the real component of the first antisymmetrical mode is the same as that of the imaginary component.Figure 133.N spans and N − 1 insulator strings. In addition, in this series of spans between dead-ends, adjacent spans may differ in length, or their supports may be at different elevations. The left end A1 that is attached to a smooth roller may be moving along the horizontal direction. The right end NA+1 is a fixed hinge. Every span as a substructure has its own local coordinate system, which is attached to the left end of each span. For i-th span, let iAiyix be a coordinate system, with the origin taken at the left end iA, the ix-axis taken along the cable chord, and the iy-axis taken along the normal direction. The dynamic displacements of i-th span, iu and iw, are measured from the position of its static equilibrium in directions parallel to the ix-axis and iy-axis, respectively.Similarly, according to the method for calculating dynamic stiffness of a two-span transmission line, the dynamic stiffness model of a multi-span transmission line with an arbitrary number of spans and inclination angles is established, as shown in A1 is subjected to a force F in the horizontal direction. If the left end A1 is subjected to an additional harmonically varying horizontal force i-th span conductor with respect to the static equilibrium position can be governed by the differential equationsτih is the additional tension in iH. iy is the static equilibrium configuration of the i-th span conductor represented by equation (2.1). The solution to the differential equation can be obtained using the technique known as separation of variables. When point A1 in multi-span transmission lines is subjected to a harmonic force, the increment displacements and additional tensions of the i-th span are given byFor the multi-span transmission lines associated with the position of static equilibrium, the left end a,b), then equation (3.1) becomesζ = ix/il. The boundary conditions at points iA and i+A1 areUsing equation (3.2i-th span. Substituting equation (3.5) into equation , the tension increment in H is given byi-th span can be divided into a normal component, ΔiT, and a component parallel to the chord joining two support points, iH. ΔliT and ΔriT are normal components of the tension acting at two support points of the i-th span. Using the separation of variables, the normal components are given byThe solutions of equation (3.3), with the given boundary conditions of equation (3.4), areiA, ΔrFi−1) and (3.10) into equation (3.11) gives,Assuming the swing angle a–c) and Finally, combining equation . The first six modes and natural frequencies calculated by FEM are shown in The accuracy and advantages of the dynamic stiffness will be demonstrated by employing typical three-span transmission lines. The same material parameters as the previous example are used. The span length of three-span transmission lines is 200–180–150 m. The inclination angles of the first, second and third spans are the same as 20°. The length of suspension insulator string is 6.47 m. The horizontal tension of the first span in the static configuration under self-weight is usually known and is set to 14.25 kN, the variation of the dynamic stiffness, 1/π is set to 3. Damping of dynamic stiffness is specified by the dimensionless factor ξ1, which is expressed in terms of the fundamental natural frequency of the associated first span lines. Figure 17a shows the real part of dynamic stiffness, and figure 17b shows the corresponding imaginary part of dynamic stiffness. Similar to the dynamic stiffness of two-span transmission lines, damping significantly affects the dynamic stiffness only at excited frequencies close to the natural frequencies of three-span transmission lines.In order to study the effects of damping on the modal shape and natural frequency, the model of three-span transmission lines, in which the span lengths are 200–180–160 m and the inclination angles are 10°–10°–10°, have been established. The geometrical parameter λa, the solid lines are the first three symmetrical modes calculated by using ABAQUS, and the scatter plots are symmetrical modes calculated by using analytic solutions. The analytic solutions are similar to equation (2.30). The symmetrical modes calculated by using analytic solutions coincide well with the FEM results obtained by using ABAQUS. As shown in figure 18b, the first three antisymmetrical modes given by analytic solutions and ABAQUS are in good agreement.As presented in figure 18a shows real and imaginary component of the first symmetrical complex mode. It is shown that the damping parameter significantly affects the shape of the real component of the first symmetrical complex mode when the value of the damping parameter is large. It is important to note that the shape of the real component of the first symmetrical complex mode is different from the shape of the imaginary component. Figure 19b shows the real and imaginary components of the second symmetrical complex mode. Similarly, the damping parameter significantly affects the shape of the real component of the second symmetrical complex mode. Figure 13c shows the real and imaginary components of the third symmetrical complex mode. It is shown that the damping parameter does not significantly affect the shape of the real component of the third symmetrical complex mode. The shape of the real component of the third symmetrical complex mode is close to that of the imaginary component. Considering the shape of the three-span antisymmetrical mode is similar to that of the two-span antisymmetrical mode, only the effect of the damping parameter on the symmetrical mode is studied.Figure 194.The closed-form expressions for the equivalent dynamic stiffness have been developed to help designers assess the dynamic response of multi-span transmission lines more accurately and efficiently. The effects of adjacent spans and suspension insulator strings are incorporated in the equivalent dynamic stiffness to improve accuracy and to extend the range of application of the dynamic stiffness. The accuracy and advantages of the dynamic stiffness are demonstrated by employing some illustrative examples. The natural frequencies of multi-span transmission lines are identified on the dynamic stiffness curve with respect to excited harmonic frequency. For the multi-span transmission lines with inclination angle in the range between −30° and 30°, a comparison of the natural frequencies calculated by FEM and dynamic stiffness further demonstrates the rationality of dynamic stiffness. The parametrical study of dynamic stiffness of two-span transmission lines reveals that the dimensionless frequency of the first symmetric mode is small compared with other frequencies. The dynamic stiffness curve shows that the effect of the second symmetric mode on the dynamic tension is greater than that of the first symmetrical mode. When the motion of two-span transmission lines is dominated by the antisymmetrical in-plane mode, the change in horizontal dynamic tension is very small.A detailed parametrical study shows that the length of insulator strings, geometrical parameter and inclination angles play important roles in the in-plane symmetrical modal shape and corresponding natural frequency. The model of multi-span transmission lines has several additional modes, due to interactions with the adjacent spans and insulators strings, which cannot be simulated by a single-span model. At certain values of the geometrical parameter, the natural frequency of a symmetric mode is close to that of an antisymmetric mode but they never coincide, while corresponding modes become hybrid modes, a mixture of symmetric and antisymmetric shapes. The lengths of two transition regions are very small, so the hybrid mode at the transition region can be obtained by employing a linear superposition of the symmetric and antisymmetric modes. The natural frequency identified by peak-to-peak of dynamic stiffness and corresponding modal shape can provide a good prediction of internal resonance condition and dynamic characteristics to guide the design of overhead transmission lines. The effect of damping on the dynamic stiffness and modal shape is studied. Some examples show that the damping significantly affects the dynamic stiffness and the modal shapes corresponding to low frequencies.


This study shows that starch-based conductive glues and electrode materials can be incorporated in EDLC systems.This work describes the use of commercially available starch as a binder for the preparation of conductive glue and electrode materials. It is demonstrated that starch can be successfully implemented as a binder in energy storage systems with non-aqueous electrolytes. These devices are characterized by a stable cycle life  at a nominal voltage of 2.5 V. Moreover, the use of starch-based conductive glue improves the electrochemical performance, especially reducing the internal resistance of the device. Starch-bound electrodes display lower equivalent distributed resistance (EDR) values than electrodes using carboxymethylcellulose (CMC) as the binder. This is due to the noticeably lower pore clogging by starch. An electric double-layer capacitor (EDLC) in organic electrolyte (1 mol L C is the capacitance (F), U is the nominal voltage (V), and ERS stands for the equivalent series, which represents all of the factors contributing to the overall value of resistance (Ω).Electrochemical energy storage devices are composed of two electrodes separated by a porous membrane and soaked in electrolyte. In particular, for electric double-layer capacitors (EDLCs), the energy is stored in an electric double layer (EDL) formed at the electrode/electrolyte interface. Cations and anions in electrolytic solution are attracted to the oppositely charged electrode surfaces, which creates an electric potential difference (voltage). The higher the nominal voltage is , the higher the energy stored 1) and power density 2), according to Equations , d is the thickness of the EDL (m), and the accessible surface area S is strictly related to the porosity of the electrode material. Equation (3) was developed later by Stern [To reach high values of energy and power, it is necessary to reach a high nominal voltage and lower the resistance of the cell. Nonetheless, the capacitance part of the equation should not be omitted. The capacitance value increases the overall energy of the constructed device and strongly depends on the electrode materials used and final cell construction, according to the equation provided by Helmholtz  (3):(3)Cby Stern , who tooby Stern . Moreoveby Stern . Additioby Stern  and Huanby Stern , where tQ is the charge accumulated (C), I is the current used during charging (A), t is the time of the charging process (s), and U is voltage (V).However, for the practical reasons the formula (4) is used to calculate the capacitance :(4)C=Q/U−1 to be achieved [Purely physical energy storage mechanisms are very fast and allow high values of power close to 10 kW kgachieved . To furtachieved ,16,17,18achieved ,23,24,25achieved ,29,30,31achieved , carboxyachieved ,34, chitachieved ,36 and cachieved , just toachieved ,39.In light of recent studies regarding starch-based binders, which present good cohesive properties, we have decided to pursue the interesting topic of “green” components for electrode preparation. In one study by Passerini , it was Starch is a naturally abundant polymer produced by many plants as a source of energy. It is worth noting that starch is the second most abundant biomaterial in nature. On the one hand, starch is environmentally friendly due to its renewable and biodegradable nature; on the other hand, it is inexpensive and widely available ,45,46. TThe abovementioned reasons were the driving force for this work, which seeks to establish a preparation method for a conducting glue based on starch for energy storage devices, which could improve the charge propagation and power performance of electrochemical devices and compete with conductive glues available on the market.TM PF-407C, Acheson, Düsseldorf, Germany). The casting and drying method was identical to that described above.The conducting glue was prepared by mixing 1:1:1 (mass ratio) deionized water (solvent), starch and soot . The mixture was stirred with a mechanical stirrer at 500 RPM at an elevated temperature of 60 °C. Once gelation of the mixture was observed, the glue was spread on the surface of a current collector. To evenly distribute the conductive glue, stainless steel foil  was placed on the perforated table of an automatic film applicator with a doctor blade attachment. The current collector sheet covered with conductive glue was transferred to a fume hood, and the excess solvent was evaporated by using a heating plate at 100 °C for 30 min. In the absence of the adhesive glue, extremely low charge propagation and high internal resistance were observed . The curVmicro < 2 nm = 0.652 and SSA = 2093 m2 g−1), 10 wt. % carbon black  and 10 wt. % starch or carboxymethyl cellulose (referred to as CMC). Distilled water was added in ratios of 1 mL to 1 g of the dry electrode material mixture to decrease the viscosity until reaching a fluid-like consistency. The mixture was stirred at 20 °C using a vacuum homogenizer until a homogeneous suspension (slurry) was obtained. In the next step, the slurry was spread on the surface of the stainless steel foil covered, with conducting glue being used as the current collector. The gap between the blade and surface of the current collector was adjusted to 100 μm. The sheet of the current collector covered with the conductive glue and electrode material was transferred to a fume hood, and the excess solvent was evaporated using a heating plate at 100 °C for 1 h. Finally, to remove water from the pores of the activated carbon material, the electrode material sheet was dried under vacuum in a dryer  overnight at 100 °C. The dried material was subjected to calendaring to further improve cohesion and adhesion. The final thickness of the electrode material was ca. 70 μm. Electrodes in the form of discs with a diameter of 10 mm were cut out using an EL-CUT precision disc cutter , and the measured mass loading for the electrodes was ca. 2 mg cm−1. The scheme of experimental procedure is presented in The electrode material was prepared according to the following composition: 80 wt. % activated carbon   at an accelerating voltage of 5 kV and a probe current of 100 pA.2 as the adsorbate.A portion of the electrode material was used for the estimation of the specific surface area (SSA) and pore size distribution (PSD) according to the Brunauer–Emmett–Teller (BET) equation. SSA was estimated using the accelerated surface area and porosimetry system ASAP 2020 . Degassing of the investigated samples was performed for 24 h at 50 °C under vacuum. Gas adsorption was carried out at −196 °C with N−1 TEBF4 in ACN, 250 μL), was introduced into the system. A VMP3 potentiostat/galvanostat  was used for electrochemical testing. The techniques included galvanostatic cycling with potential limitation (GCPL) with a current density up to 50 A g−1  in the voltage range from 0 to 2.5 V and electrochemical impedance spectroscopy (EIS) in the frequency range from 100 kHz to 10 mHz with an amplitude of 5 mV.Swagelok cells were assembled in a glove box  with an oxygen and water level below 1 ppm to determine the capacitance value. Electrodes with the same diameter and similar masses were placed in a Swagelok cell. Both electrodes were separated by a porous glass fiber separator , and then electrolyte, one molar solution of tetraethylammonium tetrafluoroborate dissolved in acetonitrile . A VMP3 potentiostat/galvanostat  was used for electrochemical testing. GCPL was performed with a current density of C/20 and C/2 in the potential range from 10 mV to 1.5 V vs. Li2 g−1, solid green line) compared to that of polytetrafluoroethylene (PTFE) , and the lowest value was detected for the CMC  bound electrode material. Based on the PSD data . The blockage of pores in AC materials by CMC has been reported by Richner et al., supporting the findings of this study [The gas adsorption analysis data presented in PSD data b, it seeis study . PristinThe SEM images demonstrate the morphologies of the electrode materials with starch a,b, PTFE−1), the lower efficiency at the initial cycles can be caused by the functional groups on surface of activated carbon. However, after several cycles it reaches the columbic efficiency of nearly 100% (−1 the observable ohmic drop (IR drop) is related with the internal resistance of the cell which increases when the value of passing current increases [−1 Na2SO4). However, this subject still needs additional work regarding the use of different types of starch and their modifications, which could prevent the dissolution of starch in water-based electrolytes for EDLCs during electrochemical cycling.rly 100% . For thencreases ,61,62. M−1 in a voltage range from 0.0 to 2.5 V. The table capacitance value (green solid line) during 50,000 cycles  and high coulombic efficiency of 98%, as shown in To establish the long-term stability of the electrode materials with starch binders, cells were continuously charged and discharged at a current of 25 A gNyquist plots  show tha−1 than the EDLC with CMC-bound electrodes (17 Wh kg−1). At high power values (>10 kW kg−1), the energy density of the cell with commercially available conductive glue and CMC binder starts to decrease, most likely because of the higher internal resistance; thus, the specific energy is 4 Wh kg−1 at a specific power of 100 kW kg−1. In the case of the EDLC utilizing starch-bound electrodes and conductive glue, it is possible to reach a high specific energy of 12 Wh kg−1 at a specific power of 100 kW kg−1. Obtained results were compared with other data found in the literature about symmetric electrochemical capacitors with carbon electrodes. All of the cells operate in organic electrolyte with TEABF4 where salt concentration is 1 mol L−1 [−1.The two EDLC systems operating at 2.5 V with starch or CMC as the binder are compared in a Ragone plot . The sta mol L−1 ,64,65,66−1, is possible for cells where the electrode material is fixed to the current collector with a starch-based conducting glue, and such cells exhibit better charge propagation, excellent capacitance retention and relatively small resistance. Moreover, preliminary studies have shown that starch binder can be used in aqueous electrolytes, which will be investigated further in the future.Starch can be considered as a “green” binder material for the fabrication of conducting glue and electrodes for energy storage devices. The manufacturing process does not involve any toxic or harmful solvents. The electrochemical characteristics of electrode materials incorporating starch as a binder and a layer of starch-based conductive glue provide better results than the commonly used “green” binder, CMC. The use of relatively high current loads, such as 50 A g


To investigate the effect of zirconia on sintering behavior, microstructure, and optical properties of transparent spinel ceramics, different contents of zirconia were added. The results show that zirconia can promote the densification process by the formation of anion vacancies. The resulting zirconia exists as tetragonal phase along the grain boundaries. The average grain size of resulting ceramics depends on the content of zirconia and HIPing condition. Small zirconia content did not deteriorate the optical properties of samples. A 5-mm-thick sample with 0.05 wt% ZrO2 pre-sintered at 1500 °C followed by HIPing treatment at 1550 °C achieved a high in-line transmittance of 75.5% at 400 nm and 85% at 1100 nm.In this paper, transparent magnesium aluminate (MgAl Transparent magnesium aluminate spinel ceramics (hereafter termed “spinel”) have been well studied for more than 50 years, since the first translucent sample was successfully fabricated in the 1960s . With th2− diffusivity, as it is the largest ion and close-packed lattice [2− in spinel structure, extreme sintering conditions of high temperature and high pressure are usually required to achieve full densification. High sintering temperature is normally accompanied by rapid grain growth, which results in low mechanical properties. At present, the key method to reduce sintering temperature is associated with nanopowder with high sintering ability [To obtain fully dense transparent spinel ceramics, the residual porosity in the sintered sample should be carefully controlled. The pore diameter of resulting samples should be under 40 nm, which markedly decreases the scattering in the visible range. Additionally, the amount of pores should be less than 100 ppm according to Mie-scattering theory ,12,13. R lattice ,15. Due  ability . However ability . When us ability .2O4 type of refractory material. The resulting samples containing zirconia (0.5–2 wt%) exhibited higher flexural strength [2 promoted densification was demonstrated by Kim [2 can enhance the cation diffusion. Nevertheless, the research on zirconia in the fabrication of transparent ceramics was rare. G. Bernard-Granger et al. chose the combination of TiO2 and ZrO2 (stabilized with 3 mol% of yttrium oxide) with tens of ppm atomic as sintering additive to fabricate transparent spinel ceramics [As reported previously, some transition-metal cations are soluble and can incorporate into the lattice, affecting the diffusion and mechanical properties by creating defects ,20. Zircstrength . The mecd by Kim .The reacceramics . The in-2O4 nanopowder to fabricate transparent ceramics. The effect of zirconia on the sintering process, microstructure evolution, and optical and mechanical properties are investigated in detail. Further, the maximum tolerance of transparent spinel ceramics to zirconia contamination can be determined.In this paper, different contents of monoclinic zirconia are added into commercial MgAl2O4 spinel nanopowder  was selected as the starting material. The primary particle size was about 55 nm. Agglomerates were mainly exceeding 1 μm. Monoclinic zirconia powder  with average particle size of ~90 nm was selected as the zirconium source. Agglomerates were ~140 nm. Into the spinel powder, 0, 0.01, 0.05, 0.1, and 1 wt% monoclinic zirconia powder were added, marked as A to E, respectively. Spinel powder with 5 wt% zirconia was prepared for further testing to investigate the possible reaction between spinel powder and zirconia at elevated temperature. The raw material without and with various contents of zirconia were mixed by ball-milling in a nylon jar with alumina balls at 250 rpm/h for 12 h. The mixed slurry was dried at 60 °C for 24 h in an oven. Then, the dried powder was sieved through a 100-mesh screen and calcined at 800 °C for 6 h to remove organic impurities. The green bodies were shaped by cold biaxial pressing at 20 MPa, followed by cold isostatic pressing for 5 min under 200 MPa pressure. Next, the green bodies were pre-sintered in a muffle furnace in air for 3 h in the temperature range of 1450–1550 °C. In order to eliminate the residual closed pores in the pre-sintered samples, the samples without open pores  were hot isostatic pressed (HIPed) at 1550 °C and 190 MPa for 3 h in argon atmosphere. For the further tests, the resulting samples were ground and mirror-polished on both sides to 5 mm thick.High-purity commercial MgAlThe Archimedes principle was employed to calculate the relative density and open porosity of pre-sintered samples. The wet weight and buoyant weight of samples were measured after boiling to ensure open pores were filled with water. The microstructure of the pre-sintered and HIPed samples was characterized by scanning electron microscopy , and a field emission scanning electron microscope  with an energy dispersive spectrometer . The average grain size  ceramic, where Zr4+ can inhibit grain growth in YAG [The thermal etched surfaces of the HIPed samples were characterized by SEM . The resh in YAG ,29. The h in YAG ,19. Whenh in YAG . Besides2O4, the random distribution of zirconia in samples acted as scattering centers, which was detrimental to the in-line transmittance. Besides, the grain size of resulting zirconia was about 300 nm, which is also harmful to transparency according to scattering theory. This was why the samples of batches D and E were opaque.To determine the distribution of zirconia in the samples, the microstructure of opaque sample E pre-sintered at 1475 °C and HIPed at 1550 °C was characterized by a field emission scanning electron microscope with an energy-dispersive spectrometer. For precise detection, the thermally etched sample was coated with carbon instead of Au to avoid characteristic peak overlap. The result  showed t2, MgO could react with pure zirconia above 1150 °C, acting as the stabilizer, to stabilize tetragonal zirconia at room temperature [2+ locates in a tetrahedron site in the lattice of MgAl2O4. To obtain Mg2+ from the spinel lattice for zirconia, maintaining the tetragonal phase must be more difficult. As shown in 2O4 during the sintering process. The most possible mechanism was that, with similar ionic radius, Mg2+ precipitated from the spinel lattice and incorporated into ZrO2, playing the role of stabilizing the zirconia as a tetragonal phase. As for spinel, the formation of anion vacancies  was mixed with spinel powder and calcined at different temperatures to detect any reaction products more easily. The calcined powders were characterized by X-ray diffraction patterns . Accordiperature ,32. HoweThe Vickers hardness and fracture toughness of samples with optimal in-line transmittance were measured, and values are shown in 2O4 ceramics with and without zirconia were successfully fabricated through pressureless sintering followed by HIPing treatment. The results showed that zirconia can promote the densification process by producing anion vacancies in the spinel lattice, accelerating mass transfer. Tetragonal zirconia was formed during the sintering process because Mg2+ can incorporate into ZrO2. With the presence of zirconia, the average grain size of pre-sintering samples was significantly affected. The final grain size of HIPed ceramics was determined by zirconia and HIPing condition. Samples with 0.1 wt% and 1 wt% ZrO2 were opaque because zirconia was randomly located at the grain boundaries, acting as scattering centers. Hence, the degree of zirconia contamination should be controlled at less than 0.05 wt%, which demonstrated no obvious influence on optical or mechanical properties. With proper control of milling loss, it is possible to use zirconia ball as milling media to de-agglomerate nanopowder for the fabrication of large-sized transparent spinel ceramics.Transparent MgAl


Bacteroidetes during spring algae blooms in the southern North Sea in 2010–2012 using a time series of 38 deeply sequenced metagenomes. Initial partitioning yielded 6455 bins, from which we extracted 3101 metagenome-assembled genomes (MAGs) including 1286 Bacteroidetes MAGs covering ~120 mostly uncultivated species. We identified 13 dominant, recurrent Bacteroidetes clades carrying a restricted set of conserved polysaccharide utilization loci (PULs) that likely mediate the bulk of bacteroidetal algal polysaccharide degradation. The majority of PULs were predicted to target the diatom storage polysaccharide laminarin, alpha-glucans, alpha-mannose-rich substrates, and sulfated xylans. Metaproteomics at 14 selected points in time revealed expression of SusC-like proteins from PULs targeting all of these substrates. Analyses of abundant key players and their PUL repertoires over time furthermore suggested that fewer and simpler polysaccharides dominated early bloom stages, and that more complex polysaccharides became available as blooms progressed.We investigated  Bacteroidetes, Gammaproteobacteria, and the alphaproteobacterial Roseobacter clade are often among the dominant and recurring responders that partake in the degradation of marine phytoplankton-derived organic matter 35] for tMass spectrometric data was analyzed using Sequest v27r11 . Searches were carried out against a forward-decoy database of all protein sequences from all corresponding metagenome samples combined  using the uclust option of USEARCH v6.1.544  , Polaribacter, Aurantivirga (GTDB-Tk genus SCGC-AA160-P02), Candidatus Prosiliicoccus (GTDB-Tk genus HC6-5), the NS3a and NS5 marine groups (GTDB-Tk genera MAG-120531 and MS024-2A), and the GTDB-Tk genus-level clade MAG-121220-bin8, which all belong to the Flavobacteriaceae family , the families UA16, 1G12, and Crocinitomicaceae (previously part of the Cryomorphaceae family), and the Cyclobacteriaceae of the Cytophagales order . In parMbp Fig. . MAGs frely Fig. .a concentration we categorized our 2010–2012 metagenomes into pre-bloom, (mid) bloom, and post-bloom periods , and the families UA16, 1G12, and Cryomorphaceae.Predicted β-glucan PULs were found for many of the abundant ely Fig. . The maiely Fig. . The shoPolaribacter and Aurantivirga. Other less abundant genera carrying this variant were Mash-clusters 9 (Algibacter-related), 10 (genus UBA6710), 34 (genus UBA1994), and 70 (unclassified on genus level).A second variant with the combination of GH16, GH30_1, and often two GH17 enzymes . This PFormosa, Polaribacter or Aurantivirga Mash-clusters. These PULs code for a combination of GH5_46, GH30_1 and GH16, though the GH16 was missing in some of the Formosa PULs. At least three such PULs were located on contigs with two susC/D pairs . Some bFormosa, Polaribacter, Aurantivirga, and an Algibacter-related Mash-cluster (mc_9). Similar types have already been reported for Polaribacter and Formosa species [Phaeodactylum tricornutum, and has been described as a linear poly-α-1,3-mannan decorated with sulfate ester and β-D-glucuronic residues [Sulfatase-containing GH92-rich PULs harbored three to four GH92 genes with up to six sulfatase genes and additional GHs of families GH2, GH3, and GH43_2 Fig. . These P species , 33, 35 residues .Flavobacterium sp. SCGC AAA160-P02 (Aurantivirga) and various Salegentibacter species in PULDB. It is noteworthy that similar PULs have been detected on Flavobacteriia fosmids from the North Atlantic, which have been hypothesized to target mixed-linkage glucans including enzymes involved in xylan metabolism (CE2 acetyl-xylan esterase and CBM9) and degradation of mannose-rich substrates (GH92 and GH130) [Formosa, Polaribacter, and Aurantivirga genera and the NS5 marine group.Sulfatase-free GH92-rich PULs contained a combination of GH92, GH130, GH20, and GH18 genes and sometimes a CBM9-containing, GH3 or GH2 gene Fig. . Often ad GH130) . The sulFormosa, Aurantivirga, and Polaribacter MAGs and have already been described to be present in marine Bacteroidetes [PULs putatively targeting sulfated xylans or xylose-rich substrates exhibited two conserved patterns. The first included a sulfatase domain-containing GH10, a GH3 and two additional sulfatase genes Fig. . The secroidetes , 35.Polaribacter and one Aurantivirga PUL were present. The alginate PULs contained varying combinations of PL6, PL7, and PL17 alginate lyase genes .Aurantivirga, Formosa, and Polaribacter clades. All other Mash-clusters contained at most three PULs, most of which were targeting α- or β-glucans. This separation of clades into narrower vs. broader PUL spectra was also reflected in the individual clade’s abundance patterns.PUL numbers per individual Mash-cluster ranged from zero to eight with the applied filtering criteria Fig. . Mash-clBacteroidetes community at Helgoland showed a clear shift from a relatively stable low diversity pre-bloom community with few PULs towards a more dynamic and diverse community with more diverse PULs during mid-blooms. In all three years the pre-bloom community was dominated by clades with streamlined PUL repertoires. Mash-clusters reaching at least ≥1 RPKM at pre-bloom time-points carried between zero and three PULs, the majority of which targeted α- or β-glucans , 14 (MAG-121220-bin8), and 15 (unclassified Flavobacteriaceae) were among the Bacteroidetes with the highest pre-bloom abundances, reaching up to 17 RPKM (~8.5% relative abundance). Mash-clusters 12 and 14 carried α-glucan PULs and Mash-clusters 12 and 15 carried β-glucan PULs , 12 (Cryomorphaceae), 15 (unclassified Flavobacteriaceae), 19 (Cd. Prosiliicoccus), and 28 (Polaribacter) reached abundances well above 10 RPKM  reached abundances of about 12 RPKM. Mash-cluster 55 carried PULs for both β-glucans and α-glucans. Towards the end of the bloom at the last three sampling time-points, Mash-clusters 8 (Formosa) and 40 (Polaribacter) became abundant. Both showed similar PUL repertoires, as both encoded PULs targeting β-glucans, mannose-rich substrates, and sulfated xylans, as well as unknown substrates.The mid-bloom bacterioplankton response was more variable in all three years, though often species of the same clades reached high relative abundances. The PUL repertoires of mid-bloom Cd. Prosiliicoccus (mc_19), Polaribacter, and Aurantivirga was less intense than in 2010  with Mash-clusters 5 and 25 contributing about equally. The Polaribacter clade reached only up to 10 RPKM and was dominated by Mash-cluster 35, which had a broad PUL repertoire targeting β-glucans, putative mannose-rich substrates and alginates  and the Formosa clade reached RKPM values above ten and only at two time-points  during the pre-bloom time-points but reached high abundances during the blooms. Thus, these clades constitute major bloom responders [Cd. Prosiliicoccus [Formosa and Aurantivirga harbored PULs for four of the major substrates targeted by Bacteroidetes during phytoplankton spring blooms and Polaribacter all five including alginate.Overall sponders . With thiicoccus  these clAurantivirga members and for putative β-glucan/laminarin PULs in Cryomorphaceae members.Components of TonB-dependent transporters are among the proteins with the highest expression in metaproteomes of phytoplankton-associated bacterioplankton. For example, in earlier studies they accounted for 7%  and 13% Polaribacter and Aurantivirga members, and expression of putative alginate PULs was detected in 2009–2011 only in post-bloom phases. In contrast, putative α- and β-glucan PUL expression was indicated throughout all bloom stages in all years.The 14 metaproteomes provided less time resolution than the 38 metagenomes, but still some trends could be observed. For instance, expression of putative sulfated xylan PULs was only indicated in 2009 during the second and post-bloom phases in Bacteroidetes have been regularly observed as major responders during phytoplankton blooms and usually outcompete other bacterial clades during early bloom phases , 72Bactees , 75Bactens (e.g. ), whereae blooms , 35, 36.Recent improvements in metagenome sequencing, assembly, and binning have enabled large-scale retrieval of PULs from natural bacterioplankton and subsequent linkage to distinct species. This approach works particularly well for bacterioplankton during early spring bloom stages, where there is low evenness due to stark proliferation of few well adapted species, some of which are almost clonal (e.g. ).susC/D gene pair. It has been shown that some PULs have susC/D pairs that are separated from the corresponding CAZyme genes elsewhere in the genome  required a rather rigid automated PUL prediction, which neglected noncanonical PULs devoid of a me (e.g. ). LikewiBacteroidetes communities were dominated by a few clades, such as Cd. Prosiliicoccus, Formosa, Polaribacter, and Aurantivirga. Mash-cluster analysis demonstrated recurrence of these clades in 2010–2012 with some interannual variability, substantiating an initial analysis of a much smaller subset of the metagenomes [Bacteroidetes to quickly respond to phytoplankton blooms with fast growth rates, while targeting only specific subsets of the glycans that algae produce. The average genome size of our Mash-cluster representatives was about 1.5 Mbp lower compared to genome sizes of isolated North Sea strains of 3.83 Mbp [Flavobacteria bacterium MS024-2A; Flavobacteria bacterium MS024-3C) are closely related to the mc_13 and mc_11 in our study. These two species feature small genomes (~2 Mbp) and ‘narrow ecological niches’ [Bacteroidetes resist conventional isolation techniques.The analyzed agenomes . This re3.83 Mbp . Two pub niches’ . It has  niches’ . Conside niches’ , it is nBacteroidetes strains [Bacteroidetes strains [The majority of abundant PULs that we describe constitute a subset of the PUL spectrum that has so far been described in isolated  strains , 35, 36. strains . Alpha-g strains ).Bacteroidetes strains [Bacteroidetes  and most diverse predicted substrate spectra. These clades all share the potential to degrade α-mannose-rich substrates and sulfated xylans/xylose-rich substrates. The coeluting sugars mannose and xylose were detected as the second most abundant monosaccharides in the total combined carbohydrates during the 2010 bloom [We observed an average of only 2.2 PULs per Mash-cluster compared to an average of 7.5 PULs for genomes of isolated North Sea  strains , and simes (e.g. ). Notabl10 bloom . Still, Cyclobacteriaceae, whereas there was considerable compositional change in others, e.g. within the broad Polaribacter clade. We observed a clear dominance of PULs targeting simple glycans (β-glucans/laminarin and α-glucan-containing substrates) in pre-bloom communities, whereas amidst blooms more complex polysaccharides were targeted as well. We hypothesize that this is the result of two effects. First, bacteria will in general prefer easily degradable substrates such as simple storage glycans over biochemically more demanding ones. Second, the availability of more complex polysaccharides increases over a blooms’ course due to increasing algae mortality rates. For example the proteome data for sulfated xylans suggests this for the year 2009. However, due to the limited time resolution of available metaproteomes (only 14 from 2009 to 2012), no clear temporal patterns in PUL expression could be observed.Throughout the entire time series some clades featured rather constant PUL repertoires, e.g. Bacteroidetes suggested that their glycan preferences are genetically hard-wired [It is still an open question which selective effects favor one of two species with similar PUL repertoires over the other. Species with similar PUL repertoires might still prefer different polysaccharides. For example, cocultivation of two gut rd-wired . In a sird-wired ).The compositional dynamics of phyto- and bacterioplankton communities during blooms are complex, as is the resulting glycan turnover biochemistry. Nonetheless, a limited number of bacterioplankton clades prevail during bloom conditions that carry a limited number of abundant PULs, which in turn target a limited number of major glycan substrates. This means that the attainment of a fundamental understanding of the bulk of glycan-mediated carbon flow during phytoplankton bloom events is within reach.Supplementary TextSupplementary Figure S1Supplementary Figure S2Supplementary Figure S3Supplementary Figure S4Supplementary Figure S5Supplementary Table S1Supplementary Table S2Supplementary Table S3Supplementary Table S4Dataset 1


Hepatic artery thrombosis can lead to graft loss associated with severe hepatic infarction or bile duct ischemia. When anatomical hepatic artery reconstruction is impossible in liver transplantation or hepato-pancreatic biliary surgery, portal vein arterialization (PVA) is proposed as a salvage technique. Herein, we report our experience with a case that showed favorable clinical outcomes after partial PVA during living-donor liver transplantation (LDLT) because of difficulties in arterial reconstruction.A 62-year-old woman with non-B, non-C liver cirrhosis complicated with hepatocellular carcinoma was being prepared for LDLT using an extended left lobe graft. The graft presented with two arteries . The first anastomosis was performed using the recipient hepatic artery stumps, but no flow was detected on Doppler control because of thrombus formation. The next attempt was executed using the middle colic artery with a radial artery jump graft and the right gastroepiploic artery, but it led to the same result. Thus, the graft oxygen support by the standard arterial procurement was abandoned, and a shunt was created between the ileocecal artery and the vein to obtain PVA. Arteriography of the superior mesenteric artery showed that the shunt was relatively patent, and the portal vein was apparent. No biliary complication or liver abscess occurred postoperatively, and the patient presented with good liver function and no complications related to portal vein hypertension, nor liver fibrosis 18 months after the LDLT.Partial PVA with a shunt created between the ileocecal artery and the vein is useful when arterial reconstruction is difficult during LDLT for preventing graft loss caused by severe hepatic infarction or bile duct ischemia. In liver transplantation, restoration of oxygenated blood supply to the liver allograft is necessary, considering that all collateral sources of arterial inflow  are completely interrupted during graft harvest . Thus, wNonetheless, portal vein arterialization (PVA) has been used as a salvage technique in case of difficulties in anatomical hepatic artery reconstruction during liver transplantation and hepato-pancreatic biliary (HPB) surgery –3. PVA iHerein, we report our experience with a case in which partial PVA was useful for difficult arterial reconstruction during a living-donor liver transplantation (LDLT).A 62-year-old Japanese female was referred to Nagasaki University Hospital to discuss an LDLT for recurrent hepatocellular carcinoma (HCC) and end-stage liver disease due to non-B, non-C liver cirrhosis. Two years earlier, she underwent trans-arterial chemoembolization. During follow-up, her liver function gradually worsened with refractory ascites. She then repeatedly received a cell-free and concentrated ascites reinfusion therapy for severe ascites. A new HCC lesion with a 1.5-cm nodule located in segment 7 was also detected by enhanced computed tomography (CT). The Child–Pugh score was 9 (grade B), and the Model for End-stage Liver Disease score was 16. Her dismal status indicated LDLT, and after an appropriate workup, an extended left lobe graft from her 35-year-old healthy daughter was voluntarily donated. Preoperative imaging findings of the donor did not exhibit calcification of the arteries or anatomical variation. Potential causes of failure of hepatic arterial reconstruction, such as a median arcuate ligament syndrome, were not present, and potential vessel injuries by previous trans-arterial chemoembolization had not occurred in the recipient. Donor surgery was performed without any difficulty in the procurement of the extended left lobe graft. The graft’s two hepatic arteries—the left hepatic artery (LHA) and the middle hepatic artery (MHA)—were anastomosed with the recipient’s counterpart microscopically, but it led to thrombosis at numerous attempts. After confirming blood flow in the anastomosed hepatic artery, we performed duct-to-duct biliary reconstruction. We noticed afterwards that we could not confirm blood flow in the hepatic artery with the Doppler US probe. Anastomosis using the recipient’s middle colic artery to the graft’s LHA microscopically through a right radial artery jump graft was attempted with no arterial flow on Doppler control. Thereafter, the arterial oxygen supply was abandoned, and an arteriovenous shunt was created between the selected ileocecal artery and the vein to obtain PVA. We used mesenteric blood vessels to perform selective portal arterialization, in reference to Hayashi et al.’s report [Laboratory analysis revealed that during the period of no oxygenation after portal reperfusion, the AST level was 100 U/L and the ALT level was 118 U/L; on postoperative day (POD) 1, these levels were 118 U/L and 89 U/L, respectively; on POD 2, 72 U/L and 149 U/L, respectively; on POD 3, 71 U/L and 145 U/L, respectively; on POD 4, 108 U/L and 159 U/L, respectively; and on POD 4, 78 U/L and 134 U/L, respectively. After POD 5, both levels decreased gradually. The patient’s serum total bilirubin levels were elevated on POD 1 but decreased gradually after the LDLT. Angiography of the superior mesenteric artery was performed on POD 3, showing a patent shunt and a clearly visible portal vein  during liver transplantation, oxygenated blood supply to the liver allograft by the hepatic artery is necessary. The hepatic artery plays a vital role after liver transplantation, especially after LDLT, providing blood for both the liver parenchyma and bile duct. Thus, if anatomical hepatic artery reconstruction is impossible during liver transplantation, a totally de-arterialized liver may occur. Eventually, biliary ischemia and necrosis take place, thereby possibly leading to liver necrosis and fatal liver failure. PVA, which allows arterial blood to flow into the portal vein, is an emergency salvage surgical procedure for cases wherein reconstructing the hepatic artery is difficult during liver transplantation and HPB surgery.Iseki et al. studied human PVA in a de-arterialized liver of a patient in whom hepatic artery ligation following arterial rupture and hemorrhage after Whipple procedure was required . SubsequAccording to some authors, calibrating the arterial inflow is important for preventing portal hypertension after PV , 9, 11. In conclusion, PVA with a shunt created between the ileocecal artery and the vein is useful in case of difficult arterial reconstruction during LDLT for preventing graft loss caused by severe hepatic infarction or bile duct ischemia.


ZmDOF36, through transcriptome sequencing analysis. Real-time PCR indicated that ZmDOF36 was highly expressed in maize endosperm, with lower expression in leaves and tassels. ZmDOF36 is a typical DOF transcription factor (TF) that is localized to the nucleus and possesses transcriptional activation activity, and its transactivation domain is located in the C-terminus (amino acids 227–351). Overexpression of ZmDOF36 can increase starch content and decrease the contents of soluble sugars and reducing sugars. In addition, abnormal starch structure in transgenic maize was also observed by scanning electron microscopy (SEM). Furthermore, the expression levels of starch synthesis-related genes were up-regulated in ZmDOF36-expressing transgenic maize. ZmDOF36 was also shown to bind directly to the promoters of six starch biosynthesis genes, ZmAGPS1a, ZmAGPL1, ZmGBSSI, ZmSSIIa, ZmISA1, and ZmISA3 in yeast one-hybrid assays. Transient expression assays showed that ZmDOF36 can activate the expression of ZmGBSSI and ZmISA1 in tobacco leaves. Collectively, the results presented here suggest that ZmDOF36 acts as an important regulatory factor in starch synthesis, and could be helpful in devising strategies for modulating starch production in maize endosperm.Starch synthesis is a complex process that influences crop yield and grain quality in maize. Many key enzymes have been identified in starch biosynthesis; however, the regulatory mechanisms have not been fully elucidated. In this study, we identified a DOF family gene,  Zea mays L.) is one of the most important food and feed crops in the world and has enormous economic and biological significance  and Brittle 2 (Bt2) genes . GBSS, encoded by the WAXY gene, is primarily responsible for amylose synthesis , granule-bound starch synthase (GBSS), soluble starch synthase (SS), starch branching enzyme (BE), and starch debranching enzyme (DBE) . AGPase 2) genes . In maizynthesis , whereasynthesis . In receynthesis . In maizynthesis .SUSIBA2, one member of the WRKY TF family, is involved in starch synthesis through an interaction with the iso1 promoter (RSR1 (Rice Starch Regulator 1), an AF2/EREBP-type TF, plays a negative regulatory role in starch synthesis , resulting in normal starch synthesis  are able to regulate starch synthesis by binding to the promoters of starch biosynthesis genes. promoter . RSR1  from a single maize growth cycle were collected and immediately frozen in liquid nitrogen and stored at -80°C until use.Maize and rice seedlings were maintained at 28 ± 2°C under a 14 h light /10 h dark photoperiod at 70% humidity in a growth chamber. Roots, stems, leaves, tassels, TM RT reagent Kit with gDNA Eraser . qRT-PCR assays were performed using SYBR Green qPCR Master Mix (Roche) in an ABI 7300 Real-Time System (Applied Biosystems). The PCR thermal cycling parameters were as follows: an initial 95°C denaturation for 10 min, followed by 40 cycles of 95°C for 15 s and 60°C for 1 min. The ZmDOF36-specific primer pair 5′-CCCGACAACTGATCCAATGC-3′ (forward) and 5′-GCATAACCACCGTCGTCGTT-3′ (reverse) were used in this study. The ZmActin1 gene was used as an internal control for normalization of gene expression levels with the specific primers 5′-AGGCTTGTCTCCCAGGTCATC-3′ (forward) and 5′-GTTGGTCTGGAACTCGTTCACA-3′ (reverse). The sequences of the primers used to amplify the starch synthesis-related genes in the qRT-PCR assays are given in First-strand cDNA was synthesized from total plant RNA using the PrimeScriptZmDOF36 gene  from the maize B73 inbred line was amplified using the gene-specific primers 5′-CGGGATCCATGGACATGAACTCCAACGC-3′  and 5′-CCGAATTCCTACCCCTCTGCCCCGTCGC-3′ . The PCR product was directly inserted into the plant over-expression vector pZZ00005  for transformation of maize inbred line “ZZC01”  and the pCAMBIA1301 vector for transformation of rice (Oryza sativa L. subsp. japonica “Zhonghua 11”). Transgenic maize plants were identified using a protein test strip for bialaphos selection; 20 independent T0 transgenic lines were obtained, and the homozygous T3 transgenic lines were obtained for further analysis. ZmDOF36 transgenic rice lines were selected by GUS staining and confirmed by PCR using specific primers to amplify the hygromycin resistance gene (HYG-F 5′-ACTCACCGCGACGTCTGT-3′ and HYG-R 5′-TTTCTTTGCCCTCGGACG-3′).The coding region of the TCTAGAATGGACATGAACTCCAACGC-3′  and 5′-CGGGATCCCCCCTCTGCCCCGTCGCTGC-3′  and inserted into the pCAMBIA1305 vector under control of the cauliflower mosaic virus (CaMV) 35S promoter. The construct was transferred into Agrobacterium tumefaciens EHA105 cells, and a suspension of agrobacteria carrying the pCAMBIA1305-ZmDOF36 construct was infiltrated into emerging leaves of 40-day-old tobacco plants. GFP fluorescence signals were observed at 20× magnification using a Zeiss LSM 780 confocal laser scanning microscope after 2–3 days of incubation.The coding sequence of ZmDOF36 without the stop codon was amplified using specific primers 5′-GCZmDOF36 were cloned separately into the pGBKT7 vector (Clontech) that carries a GAL4 DNA-binding domain. The sequences of PCR primers specific for these constructs are given in Saccharomyces cerevisiae strain AH109, and the interactions were detected on the amino acid-deficient media SD/Trp- and SD/Trp-/His-/Ade-/X-α-gal at 30°C for 3–5 days.The full-length (FL) or different truncated fragments of Grain length, width, and thickness were measured using a vernier caliper from three randomly chosen, fully filled grains. The 1,000-grain weight was determined by weighing three replicates of 1000-grain samples independently on an electronic balance.max) of amylopectin were measured as described by Endosperm was collected and then ground to a powder using a grinding mill. Finally, these powders are passed through a 50 mesh screen. The starch and amylose contents were measured using starch assay kits according to the manufacturer’s instructions . The Blue Value (BV) and maximum absorbance .TM Yeast Transformation System 2 . The bait strains were screened on SD/-Ura medium plates containing 500 ng ml-1 Aureobasidin A (AbA). The prey vector carrying the pGADT7-ZmDOF36 construct was transformed into the bait strain and were screened on SD/-Leu-AbAr defective plates for 3 days at 30°C.Promoter sequences containing the maize DOF elements (AAAG) from starch synthesis-related genes were inserted into the pAbAi vector to generate the bait vectors. The sequences of all primers used are given in ZmDOF36 cDNA was cloned into the pCAMBIA1301 vector driven by the CaMV 35S promoter to generate the effector plasmid. The promoter regions of starch synthesis-related genes were separately cloned into the pBI121 vector, which was constructed by replacing the CaMV 35S promoter with the CaMV 35S minimal promoter, to generate the reporter plasmids (Promoter-35S mini-GUS gene cassettes). Suspensions of agrobacterium strain EHA105 cells carrying the effector plasmid were mixed in equal volumes with EHA105 cells carrying the reporter plasmids and infiltrated into N. benthamiana leaves. The Agrobacterium-mediated transient expression assays, GUS staining, and enzyme activity assays were performed as previously described  of at least three replicates. Statistical analyses were performed using Microsoft Excel 2010 and SPSS v16.0 software  based on Student’s ZmDOF36 using qRT-PCR. The results of this experiment showed that ZmDOF36 is mainly expressed in the endosperm  and the N3, N4, C1, C2, and C3-terminus of ZmDOF36 grew well and appeared blue on the selective SD/Trp-/His-/Ade-/X-α-gal medium  of the protein.A yeast assay system was then used to analyze the transcriptional activation activity of ZmDOF36. The full length 7 vector . These cl medium , which sZmDOF36 encodes a DOF-type TF that may be involved in endosperm development. To explore the function of ZmDOF36, we constructed the pCAMBIA1301-ZmDOF36 and pZZ00005-ZmDOF36 vectors in which expression of ZmDOF36 is under control of the CaMV 35S promoter for rice and maize transformation, respectively. We generated 20 independent maize plants and 10 independent rice plants that over-expressed ZmDOF36. The expression levels and copy numbers of ZmDOF36 in the transgenic plants were determined by qRT-PCR  and ZmDOF36-overexpressing lines. The results showed that all parameters were apparently increased in the transgenic maize lines compared with WT, especially in the single-copy lines L11 and L16  can provide important clues about starch structure , GBSS, soluble SS, starch BE, and starch DBE are key enzymes in the starch biosynthesis pathway in the maize endosperm . To deteperiment . Starch periment , which i results  and prev results . This reZmDOF36 and pZmAGPS1a, pZmAGPL1, pZmGBSSI, pZmSSIIa, pZmISA1, or pZmISA3 .To confirm whether ZmDOF36 activates the expression of nstructs  were infnstructs  into N. activity . HoweverThe DOF TF family is a class of plant-specific TFs that are widely involved in plant growth, development, signal transduction, and the response to biotic and abiotic stress . AlthougZmDOF36 is predominantly expressed in the maize endosperm. Together, these results suggest that ZmDOF36 is a typical DOF-type transcriptional activator and may be involved in regulating the process of starch synthesis in maize.We found that ZmDOF36 is localized to the nucleus, possesses transcriptional activation activity, and is able to bind to promoter regions of starch synthesis genes containing the AAAG motif, results which are consistent with the features of DOF TFs . In addiin vitro. Therefore, transgenic maize lines overexpressing ZmDOF36 were generated to investigate the starch metabolic processes. Starch synthesis peaks at 12–15 DAP in the maize endosperm, and continues throughout later phases of kernel development (ZmAGPS1a (bt2), ZmAGPS1b, ZmAGPL1 (sh2), and ZmGBSS1 at 10–15 DAP in seeds of the transgenic lines. Importantly, ZmDOF36 was also highly expressed in 12–15 DAP endosperm in both our results and previous study  and two small subunits (AGPase SS) (waxy (wx) gene encodes GBSSI, and mutations at this locus result in the production of starch granules that lack amylose and contain only amylopectin  . Over-exPase SS) . The waxlopectin . This mamax are two major indexes that indicate the capacity of starch to combine with iodine. Different BV and kmax values reflect differences in starch structure (max as determined for amylopectin were slightly increased in the transgenic maize seeds. This result is also further demonstrated by the SEM result, which showed a loose, irregular polyhedron structure packed with larger starch granules in the endosperm of ZmDOF36 transgenic lines. SSs, Bes, and DBEs cooperatively determine the fine structure of amylopectin in a highly complex manner (ZmGBSSIIa, ZmSSIIa, ZmSSIV, and ZmBE1 was up-regulated, while ZmISA1 and ZmISA3 were down-regulated in the transgenic lines compared with WT. Changes in the relative expression levels of these genes can partially account for the observed change in starch granule size in the transgenic lines. Additional experiments will be needed to characterize the precise effect that ZmDOF36 over-expression has on the mechanism of starch synthesis, because the results of yeast one-hybrid and transient co-expression assays did not show that ZmDOF36 can bind the promoter and increase the expression of all starch synthesis genes.In addition to starch content, we also analyzed starch structure. Many studies have shown that BV and λtructure . Comparex manner . Our resZmDOF36 transgenic maize plants. Therefore, our results provide a potential strategy for breeding new maize inbred lines with larger seeds and higher starch content. Obviously, further research will be needed in the future.Interestingly, transgenic maize plants also had increased seed size and weight compared with the WT. In fact, previous studies have also suggested that rice productivity and yield are primarily sink-limited in source-sink relationships during seed development . Thus, oZmDOF36 in maize increases both seed starch content and seed size. In addition, ZmDOF36 can positively regulate the expression of starch synthesis genes by binding to a specific sequence motif in the promoter regions. Taken together, our data suggests that ZmDOF36 acts as an important regulatory factor of starch synthesis by binding to the promoters of starch synthesis genes to regulate their expression in maize endosperm.In conclusion, the results of our study demonstrate that ZmDOF36 is a candidate regulator of starch biosynthesis in maize. Overexpression of JW, LC, and BC conceived the experiments. JW, LC, MC, WZ, and QD performed the research and collected the data. JW, LC, HJ, and BC analyzed the data and wrote the manuscript. All authors reviewed and approved this submission.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.


The European Centre for Disease Prevention and Control (ECDC) invites applications for the following positions:Head of Section European and International CooperationThe application deadline expires on 26 Nov 2018.  International Relations OfficerThe application deadline expires on 22 Nov 2018.  For more information, please visit the ECDC website: https://ecdc.europa.eu/en/work-us/vacancies?f%5B0%5D=deadline_date%3A1


EJNMMI Radiopharmacy and Chemistry by an international working group of experts, the EJNMMI journal family endorses the application of the guidelines in contributions to the journals.With the open letter published in Attached to the letter by the working group is a three-page summary highlighting the most relevant issues used in the notation of radiopharmaceuticals and related terms.Nuclear Medicine and Biology, Volume 55, v – xi (2017) (10.1016/j.nucmedbio.2017.09.004)”.The full paper with all recommendations is published in “Consensus nomenclature rules for radiopharmaceutical chemistry—setting the record straight, Coenen, H.H., Gee A.D. et al., All Editors-in-Chiefs of the EJNMMI journals strongly recommend all manuscripts meet these guidelines upon submission. In addition, all reviewers will be asked to be aware of the guidelines and wherever possible to check if the guidelines are followed.Editors-in-Chief,Philip ElsingaAngelika Bischof DelaloyeArturo ChitiStefaan VandenbergheFrancesco GiammarileIgnasi Carrio


H), but had no effect on the morphological properties and X-ray diffraction patterns. A comparison of samples, made using each of the processes, showed that dual modification increased the stability ratio , which was 0.69 for dual modified starch, compared with 0.64, 0.58 and 0.44 for native, succinylated, and annealed starches, respectively. The findings of the present study are of potential use in the food industry.The objective of this study was to investigate the effects of annealing, succinylation, and a dual modification process  on the physicochemical, thermal, and morphological properties of corn starch. Specifically, the properties of interest were the water-binding capacity (WBC), swelling power, paste clarity, solubility, pasting properties, stability ratio, and thermal and morphological characteristics. The dual modification process increased the physicochemical properties  and increased the gelatinization temperature and gelatinization enthalpy (∆ Starch is an abundant organic substance that is useful to the food industry ,2. It haSuccinylation is a method that chemically modifies starch. It is an esterification reaction of a hydroxyl group in the starch molecule with succinic anhydride . It resuUnlike succinylation, annealing is a method of physically modifying starch. This process is widely used as, unlike chemical processes, it does not leave a residue . AnnealiRecently, dual modification processes have been widely used to modify starch because they can improve its undesirable properties . VariousCorn starch (12.39% moisture content), succinic anhydride, and sodium carbonate were obtained from Nacalai Tesque, Inc. .Succinylated starch was prepared by reacting native starch with succinic anhydride, with some modifications . Starch g to separate the water from the wet starch. The wet starch was dried in an incubator  at 25 °C for 24 h, ground, and sieved (100 mesh) to obtain annealed starch using a cyclone sample mill .Annealing was performed according to the method described by Vamadevan et al. , with slSuccinylated starch was obtained using the method described by Olayinka et al. , with so−1 to obtain a percentage of absorbance.FTIR spectra were recorded on an FTIR System  using KBr pellets generated by way of the methodology described in Reference , with slThe DS was determined using the alkali saponification method. A weight of 0.5 g of starch was added to a 100 mL conical flask with 25 mL of 75% ethanol. Subsequently, 20 mL of 0.5 M aqueous sodium hydroxide was added to the solution. The starch solution was stored at room temperature for 72 h, with occasional swirling of the flask. The excess alkali was back-titrated using 0.5 M hydrochloric acid . The folg for 15 min. The supernatant and filtrate were separated, and the supernatant was weighed (W2). The WBC was expressed as g g−1 of starch.The WBC of the starch was determined using the method described by Abbey and Ibeh , with slg for 15 min. The precipitate and supernatant were separated, and the precipitate was weighed (W2). The swelling power was measured using the following formula:The swelling power was measured at 95 °C according to the method described by Waliszewki et al. , with slSolubility was measured using 5 mL of supernatant, which was dried in an oven at 110 °C for 24 h. The following formula was used to determine the solubility:The paste clarity of native and modified starches was determined based on the method of Bhandari and Singhal . Starch The pasting profiles were measured using a Rapid Visco Analyzer  according to the procedure described by Wang et al. , with sow/w). The pans were sealed and allowed to stand for 30 min at room temperature prior to analysis. The samples were heated from 20 °C to 130 °C at a heating rate of 10 °C min−1. An empty aluminum pan was used as the reference. The gelatinization parameters were obtained using the Origin software .DSC measurements were conducted using a differential scanning calorimeter  based on the method of Wang et al. , with so−1 and a step size of 0.04°.The X-ray diffraction patterns of native and modified starches were observed using an X-ray diffractometer , as described by Wang et al. . The X-rThe morphology of the starch granules was observed using the method of Thao and Noomhorn . The shap < 0.05 were used to compare the differences among mean values.Data were analyzed statistically using the Origin software . Analysis of variance and Tukey tests with a significance threshold of −1 with the succinylated and dual modified starches. The DS of the succinylated and dual modified starches were both 0.15, reflecting the fact that succinylation was also performed in the dual modified starch sample. The new peak at 1572 cm−1 suggested the existence of a carbonyl group (C–O) and that succinylation occurred in both the succinylated and dual modified samples. Consistent with previous studies, the asymmetric stretching vibration of carboxylate (RCOO–) of octenyl succinic anhydride starch was located at 1572 cm−1 Annealing enhanced BD compared with the native starch. This was consistent with a study by Adebowale et al. , which dThe stability ratio indicates the resilience of starch to heat and shear stress , and is Annealing is correlated with the physical reorganization of starch granules in the presence of water . The preThe characteristics of an endothermic transition were shown by each of the starches in DSC, which appear between 60 °C and 80 °C. H) has previously been reported in corn starch [H) in barley starch after annealing indicated that annealing did not form a new double helix [Tc) and ∆H compared with the native starch. There were no significant differences between annealing and succinylation with regard to gelatinization temperature and enthalpy.There was no significant difference in enthalpy between native and annealed starch. No effect of annealing on enthalpy gelatinization (∆n starch ,42,54, bn starch , rice stn starch , or whean starch . The lacle helix , and theThe X-ray diffraction patterns of the native and modified starches are presented in Corn starch granules were observed under a light microscope, as shown in Wang et al.  suggesteThe preparation of dual modified corn starch was investigated. Our results show that dual modification increased the water binding capacity, swelling power, peak viscosity, paste clarity, gelatinization temperature, and enthalpy gelatinization, while it had no effect on solubility, granule shape, and X-ray diffraction pattern compared with the native starch. Dual modification was also shown to be more effective than succinylation at increasing the stability ratio. These results suggest that the undesirable properties of succinylated corn starch can be overcome by dual modification. The findings of this study are of potential use to the food industry in products, such as sauces that require starches that are resistant to heat and shear stress during processing. Further investigation into the use of this dual modification process is required for other types of starch.


National contributions to science are influenced by a number of factors, including economic capacity, national scientific priorities, science policy, and institutional settings and cultures. Nations do not have equal opportunities to access the global scientific market, and therefore, often seek out international partners with complementary resources and expertise. This study aims at investigating national collaboration strategies, with a focus on research leadership—measured through corresponding authorship—and its relationship with scientific impact. Results show that countries with higher R&D investments are more scientifically independent, and confirm that international collaboration is positively related to citation impact. However, leadership in international collaboration is inversely related with a countries’ share of international collaboration and there is a very little relationship between citation impact and international leadership. For instance, most countries—and particularly those that have fewer resources—have higher scientific impact when they are not leading. This suggests that, despite increasing global participation in science, most international collaborations are asymmetrical, and that the research system remains structured around a few dominate nations. In most social systems, there is a tension between cooperation and competition –2. ScienResearch councils tend to encourage collaboration among different stakeholders as part of a funding strategy to maximize impact and stimulate economic growth , 27–28. This study analyses the leadership roles of nations, using corresponding authorship of internationally co-author publications as an indicator of leadership –46. SpecRQ 1: How do collaboration practices vary across countries?RQ 2: How do advanced and developing countries vary in terms of their leadership roles in international collaborations?RQ 3: What is the citation advantage of various collaboration strategies?RQ 4: What is the citation advantage of leadership in international collaborations?RQ 5: How do these relationships vary according to the scientific capacity of nations?We consider three different types of papers , average normalized citations, as well as two indicators of scientific capacity: relative investments in R&D (GERD / GDP) and total numbers of papers. While the first indicator of research capacity is scale independent , the second one is absolute and measures the ‘raw’ research capacity of a country. We analyze relationships and patterns in each country with a special emphasis on their significance when a country acts as a leader in international partnerships.Government and industry R&D spending increasingly favors cooperation. Funding agencies, however, differ in their approach to collaboration. While European agencies foster international collaboration through funding programs , countriFor developing countries, collaboration may have mixed benefits in building scientific capacity. There is increasing recognition of the need for greater efforts aimed specifically at building the capacity of developing countries to generate, disseminate, and use S&T to address both current and future needs in national, regional, and international arenas . There rMany countries with weaker scientific capacity depend upon international collaboration, which may impede the development of their capacity and diminish attention to topics of national priority –54. StriLeadership in scientific research has been the focus of several studies. These have shown that scientific leaders are associated with a capacity to recruit necessary resources and expertise to launch and sustain projects , and areTo limit irresponsible authorship listing, the International Committee of Medical Editors (ICMJE) decided on a number of authorship criteria that should be met, and details what the role of corresponding authors is. It states that the corresponding author takes primary responsibility for communication with the journal during the manuscript submission, peer review, and publication process, and typically ensures that all the journal’s administrative requirements are properly completed. The corresponding author should be available to respond to editorial queries in a timely way, and should be available after publication to respond to critiques of the work and cooperate with any requests from the journal for data or additional information should questions about the paper arise after publication .Science, Nature, or Cell [Perception-based studies reinforce the dominant role of corresponding authorship , 37. Bei or Cell –78.The concept of a research guarantor has also been suggested as an indicator of leadership. This concept considers the guarantor not to be an individual corresponding author, but rather the research group or institution to which the corresponding author belongs. Studies on guarantors have found differences in normalized impact and corresponding author distribution depending on the international collaboration rates and degree of scientific development of the collaborating countries . The effScience Citation Index Expanded (SCIE), Social Sciences Citation Index (SSCI), and Arts and Humanities Citation Index (AHCI). For the selected period (2000–2016), the database includes 19,460,980 papers (articles and reviews). The analysis is limited to the 94 countries that produced at least 7,000 documents over the entire period studied; those account for more than 98% of the world output  papers that only have a single institution , 2) papers that have at least two institutions from at the same country , and 3) papers that have at least two institutions from at least two different countries . Leadership was measured through the country of affiliation of the corresponding author, and all others are considered as non-leading countries.The number of citations of each paper was normalized by the average citations of all papers published in the same discipline in the same year –82, to oResearch and Development (R&D) expenditures as a proportion of GDP, defined by the World Bank, were used as an indicator of the economic capacity of countries. GERD is composed of three main components: Business Expenditure on R&D (BERD), Higher Education Expenditure on R&D (HERD), and Government Intramural Expenditure on R&D (GOVERD). We categorize countries into four groups: those countries investing more than 2% (17 countries—green color); those investing less than 2%, but more than 1% (17 countries—blue color); countries investing less than 1%, but more than 0.5% (18 countries—orange color); and countries investing less than 0.5% (40 countries—red color). As shown, these groups are not of equal size.Countries vary in the proportion of their output that is a result of international collaboration . For manThese results are consistent with several previous results on collaboration, which demonstrate the effects of size, geographic proximity, and socio-political-economic affinities on the collaboration behavior of a country ,84. HoweThese differences might be explained by differences in the scientific capacity of countries. We use number of papers as an indicator of scientific activity, and GERD/GDP of countries as an indicator of funding intensity. Taken together, these indicators provide a more informed understanding of underlying mechanisms of international collaboration and leadership.R&D investments are also strongly related to citation gains , 86–87. To investigate this further, we calculate the difference between the average field-normalized citation impact on papers when countries are in leading and non-leading positions . As showrelative investment are in leadership positions. For example, Argentina achieves relatively high citation averages when leading with other countries of low scientific capacity.This does not imply, however, that there is never a citation advantage for other countries when leading. This impact is often realized in localized partnerships or in partnerships of equalized research investment. Competition in the knowledge economy is affected by several factors: differences in institutional settings and cultures , 8, natiWe found that the greater the research activity of a nation (in terms of number of papers), the more internalized the production. This is not a particularly novel finding: others have demonstrated that size often drives international collaboration , 92–93. These dependencies are not necessarily negative. Greater institutional cohesion among countries may have positive implications in nations’ performance and overall benefits for the geography of science , 95–96. While international collaboration is positively related to citation impact , intOverall, nearly all countries have higher citation impact when they do not play a leading role in international publications. However, this gain differs considerably from one country to another . From a Research leadership based on corresponding authorship and international collaboration, although limited and not equally valid in all domains of science and scholarship –46, advaIt has been argued that analyses at lower levels of disciplinary aggregation more accurately represent the strengths of countries , 90. ThiData on GERD is also imperfect. This is especially the case when grouped according to level of funding intensity, where there may exist important national disparities—particularly in the case of those countries with less than 0.5%. The use of this indicator instead of Government Budget Allocations or Outlays on R&D (GBARD) used in other studies , 87 is jAlthough indicators based on average citation counts are frequently used, they are also criticized in the literature –102. AddStrategies for international collaboration do not equally benefit all countries. A disproportionately high reliance on international collaboration may imply that a country lacks the resources necessary to be independent. Collaboration may facilitate scientific advancement in that country, but it comes at a cost. For relatively disadvantaged countries, there is no citation benefit to lead research, but there is one for collaborating. In an era where bibliometric indicators play an important role in the allocation of resources, this may dissuade researchers and institutions from developing and leading their own research agenda, with potentially negative consequences in terms of linguistic and topical diversity. Robust science policy must take into account inequalities in labor and reward rather than defaulting to a universal strategy towards international collaboration.S1 Fig(XLSX)Click here for additional data file.S2 Fig(XLSX)Click here for additional data file.S1 Table(XLSX)Click here for additional data file.