CD and CL simultaneously.The present study proposes aerodynamically optimized exterior designs of a sport utility vehicle using computational fluid dynamics analysis based on steady-state Reynolds-averaged Navier–Stokes turbulence models. To achieve an optimal design, modifications of the outer shape and adding some aerodynamic devices are investigated. This study focuses on modifying this vehicle model’s upper and front parts. At the same time, the rear diffuser and spare tire on the back door as a fairing are used as aerodynamic devices for improving streamlines. All these modifications and add-on devices are simulated individually or in combination to achieve the best exterior design. A variety of Reynolds numbers are used for determining the optimization variables. Tetrahedral cells are used throughout the global domain because of the sharp edges in the geometry of the Discovery car model. At the same time, prism cells around car surfaces are adopted to improve the accuracy of the results. A good agreement between the numerical drag coefficient in the present study for the baseline models and the experimental data has been achieved. Changes in the drag and lift coefficients are calculated for all models. It is clear from the numerical results that the use of combined modifications and add-on devices has a significant effect in improving the overall aerodynamic behavior. As a result, the drag coefficient for the optimal design of the Discovery 4th generation is reduced from 0.4 to 0.352 by about 12% compared to the benchmark. Simultaneously, the lift coefficient is 0.037 for optimal design, and it is an acceptable value. It is found that combining all optimal modified configurations can improve both  Using smooth curved surfaces and aerodynamic devices helps achieve streamlined geometries4. The aerodynamic behavior of automobiles can be tested experimentally by using a wind tunnel or numerically by using CFD5.Most of the braking system research focuses on advancing current technologies, such as active suspension systems, automatic anti-lock braking, traction control devices, and brake disk thermal characteristics. Researchers are also being carried out in the field of technologies that assist the driver by providing a warning or automatically commencing brakes when a collision risk is recognized. Despite its relevance, only a little research on how aerodynamics might improve the braking characteristics of passenger vehicles and its possibilities can be discovered in the literature. Most research yet has focused on high-performance vehicles like racing cars and high-end sports cars, making it difficult to determine how far this innovation can be transferred to passenger automobiles. It should be remembered that active aerodynamics was outlawed from racing in the late 1960s. One of the reasons for this choice was a safety concern, as moveable parts were not as firmly mounted as the problems were affecting. Active aerodynamic components were utilized in racing automobiles to boost performance, which was sometimes more vital than the driver's safety. The active aerodynamic devices that were first utilized in racing vehicles were created with limited knowledge of how they worked. As a result, they were more likely to have catastrophic defects that revealed themselves when the vehicles performed to their maximum ability during a race. Aerodynamic forces were frequently passed straight to the unsprung sections of the suspension, which conveyed road shocks to the wing's nodes. When looking at photographs of cars from that era, one can see that the designers understated the increase in a vehicle's performance when driving around a bend, leading to greater lateral pressure conveyed by the tires also and acting on the highly placed wings, which could outcome in the wing dissociating from the car. The only exception to the energetic aerodynamics bans in Formula One today is a drag reduction framework, which consists of a movable airfoil that lowers its angle of attack on straightaways to generate flow separation on the main airfoil, reducing downward force and the high parasitic drag produced on the very low aspect wing and minimizing total drag. The usage of rear wings and spoilers in braking mode is frequent in supercars, demonstrating that active aerodynamic features are protected in operation if properly built. The exterior design of road vehicles has a great influence on fuel consumption. Streamlines vehicle shapes can reduce fuel consumption, which reduces pollution7. That leads to a reduced drag coefficient from 0.41 to 0.410. In 2017, the 5th generation of Land Rover Discovery appeared with a new streamlined exterior design. This model was investigated experimentally and numerically to calculate the drag coefficient11. Different aerodynamic devices were tested on the Land Rover Discovery 4th generation (LRD4) to achieve optimal aerodynamic behavior13.Relatively sharp edges and semi-straight lines characterize the exterior design of the Land Rover Discovery 3rd generation. A stepped roofline is the main characteristic of this vehicle. Then came the 4th generation of this vehicle with slight improvements to the exterior design. A wind tunnel with a fixed ground supported by a limited numerical approach was used to develop this SUV15. The rear screen and rear fairing are examples of passive aerodynamic devices. These add-on devices were investigated experimentally with a scale SUV model to reduce 16. In comparison, base bleed and rear cavities were analyzed experimentally for a full-scale SUV model to achieve the greatest drag reduction17. Closed and open cooling apertures for SUVs were studied experimentally to know their effect on drag resistance18. Pressure and drag coefficients were examined experimentally and numerically for the 1/5th Fiat Linea model in different blockage ratio magnitudes to investigate the effect of the blockage ratio on the 19. A rear diffuser was studied for a sedan car using a numerical method to decrease 20. The base pressure is most important to calculate in the aerodynamics of SUVs because it can result in about half of the overall air resistance21. Some add-on devices are suitable for improving the lift coefficient but negatively affect the drag coefficient. A rear spoiler similar to a wing was used to increase the car's stability on the road and reduce noise22. The optimizing exterior design of a passenger car can minimize air resistance. As proof, the 23. 27.SUVs and station wagon cars have more air resistance than sedan models. Due to a high rake angle, the airflow separates early in such vehicles at the roof end. This phenomenon can lead to a rise the drag resistance due to a high degree of turbulence behind the vehicle6 and 14.6 × 106 of Many studies have focused on the reduction of 30.SolidWorks (version 2014) software is used to create all vehicle geometries in the present study, while all numerical simulations are achieved by using ANSYS Fluent31. All simulations are achieved by using a realizable k–ε turbulence model. The following transport equations are used for 32The motion of fluid flow can be represented through the governing equations. Navier Stokes equations, governing equations, are based on the conservation of momentum, mass, and energy. Most numerical studies of external flow are based on RANS equations32The following equation is the eddy viscosityThe following equations are the transport equations in the realizable 5The 5While the following equation is used to calculate 37. This model has a 0.4 drag coefficient because of its non-streamlines exterior design11. SolidWorks software is used to create this computational model. Overall length, height, width without side mirrors, and the wheelbase of the LRD4 are 4.835 m, 1.887 m, 1.915 m, and 2.51 m, respectively9. Figure SUVs have been more prevalent in the last decades because they are safer than other models and have more cargo room. Therefore, studying and improving SUVs are more important than other vehicle models. LRD4 is used in the present study as a benchmark for SUVs because numerous academic references describe the car's properties and overall aerodynamic behavior38. The width and height of the second computational domain are set larger than in a MIRA wind tunnel39 to avoid the effect of a possible wall boundary layer. A frontal projected area of this computational domain is 123.66 m2.A cube tunnel is used as a computational domain in the current study. Two different sizes of the computational domain are used. The first size is similar to the wind tunnel used in experimental tests to validate the numerical simulation results. While extra dimensions are used in the second computational domain, as recommended by Al-SaadiThe computational domain length is about 8.5 of the LRD4 length. Figure 6 cells for half computational domain are chosen for all simulations after some testing for computational time and accuracy. The optimal mesh for the benchmark of the LRD4 model is shown in Fig. Mesh quality in the whole computational domain is an extremely critical step in numerical simulation. The unstructured tetrahedral cells in the global domain are generated by using ANSYS meshing with varying levels of refinement. This type of mesh is used to cope with the complexity of vehicle geometry. Figure k–ε model was more accurate than other turbulence models37.Depending on where it concerned the vehicle's surface, y+ employed an aspect ratio smaller than 30 for all Discovery car configurations in the current investigation. For this reason, the realizable Re between 7.3 × 106 and 14.6 × 106). The current study applies the mass flow rates , it is clear that after about 800 iterations, the solution of these equations no longer changes. The residuals of k and epsilon were less than 5 × 10–4. Also, the residuals of all velocities are reduced to less than 10–6. Only the residual of continuity decreased to less than 5 × 10–3. Each case of simulation run needs at least 36 h to finish.Through convergence equations for the 10. The numerical simulations provided great agreement with all experimental data.Table Most vehicle engine power is used to overcome the air resistance at high speed, especially with a non-streamlined vehicle design. The benchmark of the LRD4 has a high Placing a spare tire behind the vehicle as fairing is the second modified model for the LRD4. Another modified model is created by adding a diffuser to the modified LRD4. The last modified model is performed by combining all modifications of the LRD4. The computational domain of redesigned LRD4 and LRD4 with aerodynamic device models is similar to the computational domain of the benchmark of the LRD4. Unstructured tetrahedral mesh with three VCRs is used for all modified LRD4 models throughout the computational domain. Figure Some modifications for the exterior design of LRD4 are proposed while preserving the main car dimensions except the overall height. The main modification is in the upper part of the LRD4 to achieve a curved roof. Many different sizes are tested in order to achieve the optimal roof dimensions for LRD4. Some sharp edges in the front part of the LRD4 are changed to soft curved. Figure All configurations of the modified exterior design of the LRD4 have In addition to exterior design modifications, two aerodynamic devices are investigated for the modified LRD4 model. Use a spare tire on the back door as a fairing to achieve a more streamlined model. The Discovery car with a spare tire on the back door has a better-streamlined look than the benchmark and modified models because the spare tire covers a part of the wake zone behind this car. This model has a lower pressure zone behind it. Figures Using a diffuser under the rear bumper is the second proposed aerodynamic device for the modified LRD4, as shown in Figs. Combined optimal modifications and aerodynamic devices can reduce the drag coefficient, which leads to reduced fuel consumption. Figure 38. It is clear that increasing in Four models of the modified exterior design of the LRD4  are analyzed to achieve an optimal LRD4 model. Figure Figure Representation of pressure distributions on the vehicle surface is done using the pressure coefficient , and adding a spare tire to the back door can reduce CD by 10.75% (CD = 0.357). The best modifications in the current study in terms of CD = 0.352) and CL = 0.037) simultaneously are achieved by combining changes of redesigning the exterior shape, placing a spare tire on the back door, and adding a diffuser underbody. This configuration has reduced CD by about 12%.The massive number of LRD4 configurations are investigated in the present study using the realizable All data generated or analyzed during this study are included in this published article.


Congratulations, you have completed your registrar training! You feel elated until you realise you have to go through all the administration of registering with the Health Professions Council of South Africa (HPCSA) as a specialist. Despite what some of your colleagues might tell you, it is not a very tiresome process.Here are the steps and practical tips to register as a family medicine specialist with the HPCSA as informed by my own experience:■You have passed the Colleges of Medicine of South Africa (CMSA)’s Fellowship of the College of Family Physicians Part A written examination.■You have completed your research and passed the CMSA’s Fellowship of the College of Family Physicians Part B.■You have completed your registrar training time.■You have satisfied all the criteria to obtain your Masters of Medicine (MMed) in Family Medicine from your University.Firstly, ensure you have satisfied the following necessary criteria to register as a family physician:■1. This form should be completed twice, once for your MMed (Family Medicine) and again for your Fellowship of the College of Family Physician (FCFP). (1) Complete Parts A and B. (2) Submit the proof of payment of the registration fee paid. The updated amount and banking details are on the HPCSA website. In 2021, the amount was R500.00 per additional qualification; a copy of your marriage certificate (should you wish to register in your married surname); your original degree/diploma certificate  Copies certified by a Commissioner of Oaths will not be accepted. Alternatively, you can hand in Section C duly completed by the University or College; If you complete Section C, the original official date stamp of the institution should also be on the form.Form 19 – Application for registration an additional qualification or category■2. (1) This form must be completed in detail and correctly. Information regarding experience must be provided in chronological order. (2) Attach your service record with your experience and posts held from internship onward and provide the exact post held and time spent in each post (beginning and end dates must be clearly indicated). You will be able to get this from your human resources department in the respective hospitals you have worked. (3) Proof of payment of the registration fee paid. The updated amount and banking details are on the HPCSA website. The amount was R6590.00 in 2021.Form 21 – Application for registration as specialist/sub-specialist■3. (1) This form must be signed by the head of your academic department, medical superintendent of the teaching/satellite hospital/department/facility and the Dean . (2) There should also be a university date stamp on the form. (3) If training was conducted in several teaching hospitals with different training post numbers, each teaching hospital should confirm training by completing a different form 57.Form 57 – Certificate relating to training in specialities and sub-specialistYou should get the following HPCSA forms completed:■Certified copy of your identity document.■Your ethics committee approval letter for your research.■Proof of your CMSA Pass letter and breakdown of results or copy of your degree certificate.■Proof of your MMed Pass letter and breakdown of results or copy of your degree certificate.Other documents not specified, but recommended to also attach to your application, include:The HPCSA has an online service option to register your additional qualifications and as a specialist online. You upload electronic versions of your documents online. However, you will still need to send the original forms to the HPCSA office.■The Registrar, PO Box 205, Pretoria 0001 or■553 Madiba Street, Arcadia, Pretoria 0083.■You can also drop it off at their office at the same address mentioned here.Alternatively, you do not have to do the online application, but you can just send the original forms by registered mail or courier to:Some additional tips:Try to get your registration with the HPCSA done as soon as possible. If there are any delays, it will not hamper you from applying for a post.Be sure to save up some money for your registration; it is quite a hefty amount.Complete the forms legibly and in black ink.Make sure you do not make any mistakes on the forms. The HPCSA accepts no alterations on the documents.Be sure to know your HPCSA board-approved registrar post number, as you will need this to complete your forms. Your human resources department or university will be able to provide you with this.A courier is the best option for sending your documents to the HPCSA if you can’t hand it in yourself. It is probably more reliable, because you will be able to track it.4 on the HPCSA website.For further information, consult the HPCSA guideline for registration as a specialistSouth African Family Practice (SAFP) journal written with the Next 5 audience in mind and informed by a membership survey.5 If you are keen to learn more about this initiative and wish to become involved, please email to admin@saafp.org.The Next 5 is an official South African Academy of Family Physicians (SAAFP) initiative aimed at assisting newly qualified family physicians within their first 5 years of qualifying. ‘Transition tips’ is a regular feature in the


Many aquatic and aerial animal species are known to utilise their surrounding flow field and/or the induced flow field of a neighbour to reduce their physical exertion, however, the mechanism by which such benefits are obtained has remained elusive. In this work, we investigate the swimming dynamics of rainbow trout in the wake of a thrust-producing oscillating hydrofoil. Despite the higher flow velocities in the inner region of the vortex street, some fish maintain position in this region, while exhibiting an altered swimming gait. Estimates of energy expenditure indicate a reduction in the propulsive cost when compared to regular swimming. By examining the accelerations of the fish, an explanation of the mechanism by which energy is harvested from the vortices is proposed. Similar to dynamic soaring employed by albatross, the mechanism can be linked to the non-equilibrium hydrodynamic forces produced when fish encounter the cross-flow velocity generated by the vortex street. Such precise, complex flight and swimming dynamics require high-skilled manoeuvring and hydro- and aerodynamic mechanisms to benefit their motion, which are currently only partially understood.Aquatic and aerial animal species are well known to utilise their surrounding flow field and/or the induced flow field of a neighbour to reduce their physical exertion, enabling them to travel over longer distances. Examples include hydrodynamic drafting observed in mother–calf dolphin pairs7. One of the earliest explanations postulated was that the follower fish could gain thrust derived from the induced flow-stream between two parallel reverse Kármán vortex streets generated from a pair of leading fish7, although this theory only works for a specific relative positioning of three fish. Recent studies have shown that leader swimmers also derive energy benefits from followers at close distances10. However, it is well known that shoaling fish do not adopt a fixed distance swimming formation and that the nearest neighbour distance is continuously changing12. Additionally, computational studies and modern machine learning methods have revealed relative positioning and kinematics that allow both the leader and follower in a fish pair to obtain an energy benefit. By combining high fidelity flow simulation with reinforcement learning algorithms, Verma et al.13 demonstrated that an off-centre following position was energetically advantageous, rather than in-line swimming.The perfectly synchronised movement of fish swimming together in an organised pattern, known as shoaling or schooling, is exhibited by many fish species, yet surprisingly limited comprehensive hydrodynamic explanation for the benefits of collective swimming exists. Broad explanations have been offered based on the follower fish capturing energy from vortices generated from the leading fish to reduce energy expenditure17. The term “Kármán gaiting” was coined for fish tuning their body wavelength and lateral translation to match the Von Kármán vortex shedding frequency20. Although Kármán gaiting has been shown to be energetically advantageous for fish by reducing their energy costs and enhancing their swimming efficiency21, with the mean velocity in the wake of objects generating the vortex street being lower than in the free stream, decoupling benefits of Kármán gaiting and staying in areas of calmer flow has not been feasible. While flow structures in Kármán gaiting appear similar to those in collective swimming, a key distinction can be made in terms of characteristic shedding frequencies. Collective swimming typically occurs close to the natural tailbeat frequency for a particular species22, however, in the case of Kármán gaiting, an additional oscillatory component appears at a frequency offset from that of regular swimming.The case of fish swimming behind wake-forming obstacles such as vertical cylinders has been studied extensively, where fish alter their locomotion by synchronising their swimming gait with the unsteady Von Kármán vortex street24, and experiments have replicated this vortex system using robot fish and oscillating aerofoils to control the wake dynamics while using real fish in the wake as the follower fish26. Such experiments have highlighted two independent kinematic behaviours, one, that the follower fish adjusts its tail beat frequency to match that of the leader fish, and two, the follower’s station holding depends on the relative spatial positioning27. The recent study by Li et al.22 has advanced this understanding by showing that the tail beat/vortex frequency matching of the follower fish to that of the leader fish is maintained at a precise phase difference, which is a function of the relative spatial positioning.A number of studies have focused on fish swimming in pairs to gain further understanding of the hydrodynamic incentives of collective swimming. The oscillating motion of a leader fish swimming in carangiform mode, creates a thrust generating reverse Kármán vortex street in its wakeOncorhynchus mykiss). By superimposing flow visualisation and velocity measurements with fish tracking data, new hydrodynamic insight is obtained, highlighting inertia as the main mechanism for dynamic station holding.In this paper, we provide a linked hydrodynamic and kinematic explanation of the use of the periodic cross-flow generated in a thrust generating Karman vortex street by juvenile rainbow trout , a wavelet analysis of the curvature of fish muscle was performed. After studying dissections of the sub-carangiform swimmers, the fish muscle has been assigned to span from 1/3 to 13/16 of the body length, measured from the front of the head. The power spectrum of the tailbeat amplitude in the different regimes is shown in Fig. To quantitatively assess the difference in energy expenditure between regimes, we analysed the curvature of the fish centerline and estimated the fish propulsive power to be proportional to the rate of the volumetric contraction of the muscles. Further details of the method of propulsive power estimation are presented in the supplementary material.It has been found that, in the foil frequency range between 1.4 and 2 Hz, the estimated energy expenditure in the swinging regime is consistently lower than that when swimming regularly outside of the wake, with an average benefit reaching 25% as shown in Fig. To provide insight into the physics of the altered swimming gait, the accelerations of the fish centre of volume are examined. Figure By examining the projections of the hydrodynamic forces acting on the fish, the explanation of the mechanism can be expanded. As shown in Fig. In addition to adjusting their cross-stream position with respect to the vortices to reduce energy expenditure, the curvature of the fish body has also been observed to adapt to the vortical flow field. Figure 29, the curvature phase can be seen to vary linearly with distance to vortex.The phase of the additional oscillatory component of the body curvature developed at the hydrofoil oscillation frequency can be extracted by band-pass filtering the body curvature amplitude in the vicinity of the foil oscillation frequency, followed by computing the Hilbert transform of the filtered signal. Fig. 18, where a similar Kármán gaiting frequency was observed with three times larger fish in a flow of three times the velocity.Evaluating the propulsive force is difficult not only as calculating the required lift and drag coefficients is challenging with a highly 3-dimensional flow, but also because the Strouhal number based on the fish length varies in the range 0.4–0.8, which suggests that time-dependent effects need to be accounted for. However, to illustrate the feasibility of the cross-flow-based propulsion mechanism, we evaluate the characteristic time entclass1pt{minima32 in the sense that both lateral and angular positions are achieved by smart orientation of the whole fish with respect to the surrounding flow structures rather than by application of an external force to a propulsive fin. The shape of the fish body in different gaiting phases maximises the propulsive component of force and provides steering to compensate imbalances in the yawing moment.In conclusion, rainbow trout have been observed to swim with an altered gait in a thrust generating reverse von Kármán vortex street produced by an oscillating hydrofoil, which can be associated with the flow generated by a large leader fish. The rainbow trout synchronise their body movements with the vortices and exhibit a large cross-flow oscillation in their centre of mass position. This leads to a reduction in energy expenditure, exceeding the loss incurred due to the higher streamwise velocity in the wake. The altered gait differs from the behaviour of similar-sized fish swimming in schools as it occurs at frequencies significantly lower than the natural tailbeat frequency of a fish swimming alone or in a school. Rather than slightly tuning the tailbeat frequency to match that of a leader, fish use their body inertia and orientation to exploit the non-equilibrium hydrodynamic forces generated when exposed to the alternating cross-flow. This allows them to generate additional thrust and reduce their energy expenditure. Despite visual similarity, the swinging is different from the extensively studied pitching or heavingThe mechanics of fish extracting energy from the alternating cross-flow is similar to that of dynamic soaring of albatross, where the stationary gradient of the cross-flow in the atmospheric boundary layer is exploited. The difference is that albatross actively change height moving between fast and slow cross-flow, while fish follow the upstream path while vortices pass by.Juvenile rainbow trout  probe was traversed across the test section in 2 mm increments. Velocity measurements were obtained with a sampling frequency of 200 Hz at 10 positions along the UVP beam, which was inclined at Flow visualisation of the vortex street was performed by manually injecting food colouring at the leading edge of the hydrofoil close to the mid-depth position. Images were captured with a FLIR Grasshopper camera mounted above the flume, as for the capture of the fish kinematics.The energy expenditure of the fish was linked to the contraction of muscles along the body associated with bending in horizontal direction. It has been assumed that the work performed by muscles is defined by the textbook value L was multiplied by the moment of area A of the muscle calculated from fish cross-sections and then integrated along the length of the muscle as follows:x is directed horizontally perpendicular to the fish plane of symmetry, and y is vertical. The contours of fish cross-section are evaluated from a dissected species. The power has been evaluated in arbitrary units and not converted to Watt. While the location of the muscle along the fish body between 1/3 and 3/16 is somewhat arbitrary, the power expenditure does not significantly depend on these numbers because the energy produced close to the ends of the interval vanishes: The body curvature is nearly zero from the head to the vicinity of 1/3 and the muscle cross-section is nearly zero from the vicinity of 3/16 to the tip of the tail. Due to the lack of literature on the calculation of the energy expenditure from the fish body shape, we have attempted a variety of methods which all lead to the same qualitative result: In the swinging regime, fish spends notably less energy.Supplementary Information.Supplementary Video 1.Supplementary Video 2.Supplementary Video 3.


Scientific Reports 10.1038/srep45608, published online 13 April 2017Retraction of: Editors have retracted this Article.After publication of this paper concerns were raised about unusually high level of similarity in the background noise for two different samples in Figure 3B, as well as for two sets of samples in Figure 3A. The Author was able to provide data for this figure, but these did not resolve the Editors' concerns. The Author is also not able to provide the original data for the other figures. Editors therefore no longer have confidence in the results reported in this study.H.-Y. He agrees with the retraction and its wording.


Density Functional Theory (DFT) calculations are used to examine the defect processes, the electronic structure and the thermodynamical properties of halogen-doped SnO2. Calculations show that halogen doping reduces the oxide bandgap by creating gap states which agree well with our experimental data. The crystallinity and morphology of the samples is also altered. The synergy of these effects results in a significant improvement of the gas-sensing response. This work demonstrates for the first time a complete theoretical and experimental characterization of halogen-doped SnO2 and investigates the possible responsible mechanisms. Our results illustrate that halogen doping is a low-cost method that significantly enhances the room temperature response of SnO2.The increasing demand for efficient sensing devices with facile low-cost fabrication has attracted a lot of scientific research effort in the recent years. In particular, the scientific community aims to develop new candidate materials suitable for energy-related devices, such as sensors and photovoltaics or clean energy applications such as hydrogen production. One of the most prominent methods to improve materials functionality and performance is doping key device component(s). This paper aims to examine in detail, both from a theoretical and an experimental point of view, the effect of halogen doping on the properties of tin dioxide (SnO Nevertheless, hydrogen as a fuel is challenging to implement due to the difficulty to store, wide flammability and detonation range, ease to diffuse through numerous materials that could lead to the embrittlement in container metals3. Hydrogen is difficult to detect as it is colorless, tasteless and odorless3. Therefore, it is necessary to form sensors with high-sensitivity, low energy consumption and easy of fabrication4. Different gas sensors are mainly classified into optical, thermoelectrical, and conductometric 7. Nowadays, metal oxides are noticeable for sensing applications due to their crystalline size, physical, chemical properties10.The advent of the hydrogen economy will be advantageous due to the comparably lower CO2) is a semiconductor material with n-type conductivity and a bandgap value of 3.7 eV, widely used as a sensing element11. However, some characteristics of SnO2, such us low selectivity, long response time and high operation temperature, restrict its successful application to hydrogen sensors. Many processes have been adopted to address these issues, such as surface passivation with noble metals 13. Notably, among the different deposition methods for SnO2, the sol–gel spin-coating process has many benefits for producing high-quality samples, including safe and straightforward fabrication with low-cost14.Tin oxide , chlorine (Cl), bromide (Br) and iodide (I), doping. Regarding the surface, we focus on the (110) facet and discuss the changes in the bandgap and the connection to the electrical conductivity from a theoretical viewpoint. Furthermore, we prepared five SnO2 thin-film samples, namely F:SnO2, Cl:SnO2, Br:SnO2 and I:SnO2 by using inorganic salts as solution precursors with the sol–gel/spin-coating method. The characterization of the crystalline structure and the electrical characteristics for the deposited thin films were analyzed using X-ray diffraction (XRD), atomic force microscope (AFM) and a four-point probe. We tested the sensing characteristics towards hydrogen gas of the doped SnO2 thin-films at room temperature. Here, we find that the room temperature response is highly improved when SnO2 is coated with just a small amount of Pt. The improvement of gas response caused by the addition of Pt- islands created on the surface can be attributed to one main reason: catalytic promotion obtained by the Pt particles, which also results to the formation of p–n junction between PtOx and SnO215. In this work, Pt particles are inserted in a small amount by using physical vapor deposition for 15 s. In the literature, many reports focus on the effect of fluorine doping in the electrical and optical properties of SnO217. Specifically, fluorine dopant increases tin dioxide's conductivity and transparency, making it a better candidate for optoelectronic devices and gas sensors. In SnO2, it was previously shown that fluorine dopant occupies oxygen sites when inserted in low concentrations both in the bulk and the surface18. As fluorine has a higher electronegativity compared to oxygen19, the incorporation in the surface can attract more oxygen for the adsorption process and thus improve the response of the SnO2 sample towards hydrogen. Following this concept, halogen doping is a low-cost and easy to fabricate method to create more active sites for adsorbed oxygens or even hydrogen without significantly changing the properties of SnO2. Combining these characteristics with the band-structure manipulation, herein all the halogens are examined both in interstitial and substitutional position and then the sensing response towards H2 of the samples is discussed before and after doping. For the halogen dopants, NH4F, NH4Cl, NH4Br and KI were used as precursors, while SnO2 was fabricated using SnCl2 ˙ 2H2O.In this work, we use density functional theory (DFT) to investigate the structural, electronic properties of the bulk and surface SnO20 and are in a good agreement with the calculated lattice parameters (a = 4.717 Å and c = 3.189 Å) In Figure In the calculations a DFT a supercell consisting of 72 atoms is used. The experimental cell parameters are a = 4.737 Å, c = 3.142 ÅAs it is shown in Table ΔΗf). The formation energy gives the energy requires to construct the structure by considering the chemical reservoirs of the structure. The formula for ΔΗf is:E D,q is the is the total energy of the defective supercell when the defect is in charge state q, EH is the initial energy of the undoped host supercell, μi is the chemical potential of the atom removed or added. The free parameter in this equation is the Ef which represents the Fermi energy of the system with reference to the Valence band Maximum (VBM) which has energy 20. There are not many reports regarding the formation energy of halogen dopants in SnO2. Williamson et al.21 predicted the formation energy of F:SnO2 at a value of 3 eV for the interstitial and 2.5 eV for the oxygen substitutional at 800 K and 1 atm environment. Behtash et al.22 examined the iodine doping of SnO2 and predicted that for the oxygen substitution the formation energy varies from 5 to 7.5 eV depending on the definition of the oxygen’s chemical potential. This value agrees well with the present prediction. Cheng et al.23 also worked on the halogen doping in SnO2 using the Perdew-Burke-Ernzerhof (PBE) functional for the structural properties and Heyd–Scuseria–Ernzerhof (HSE06) for the electronic calculations and his values agree well with the predicted formation energies.We use the formation energy to predict the energy cost to construct the halogen doped structures (entclass1pt{minima2 the density of states (DOS) is calculated before and after the halogen doping. The doping percentage is one halogen atom per 72 SnO2 atoms, which results in a 1.38% doping percentage. The electronic properties are calculated through the PBE0 exchange–correlation functional and the bandgap of SnO2 is computed to be 3.35 eV, in good agreement with the experimental band gap (3.7 eV24). This functional has also been used in other theoretical studies with similar value for the undoped case21. As it is presented in Fig. 2 gives rise to some additional energy states inside bandgap. These states originate by the hybridization of F-2p orbital with the nearest O-2p. The bandgap after the Fi incorporation is reduced to 3.00 eV. When F is inserted in O-substitutional position, additional states are created near the valence band maximum  The bandgap reduction helps the transition of charge carriers and thus it can be beneficial for the oxygen adsorption, b) The increase in Fermi energy affects the surface conductivity properties of the material, c) The mid-gap states can be beneficial for the sensing applications as they trap electrons which can be used from the adsorbed oxygen atoms and speedup the sensing process when the gas molecules are inserted. It is known that the gas sensing mechanism is highly connected with the trapped electrons, which mainly occur due to the gap states formed by the oxygen vacancies, as a result, it can be assumed that the combination of trap states due to halogen doping as well as the addition of more active sites due to the surface dopants can possibly improve the response towards a target gas. In Table 25 are presented.Lastly, I interstitial and substitutional doping is examined. It is calculated that the bandgap is reduced to a value of 2.45 eV for the interstitial Fig. g and 2.72 based sensing materials with high response and sensitivity, attention should be given on the surface doping. Theoretical simulations of the effect of surface doping on the electrical properties of SnO2 are less frequent in the literature, compared to the bulk system. In this section, attention is concentrated to the investigation of the electronic properties of the surface, before and after halogen doping. For the modelling of the surface a slab model with an (110) orientation is used, with a vacuum of 14 Å  facet is the most stable low-index surface and it is a common choice for the simulation of the surface properties of SnO226. The modelling of the surface is important as the gas adsorption and gas reactions take place mainly on the facets of the sample. Specifically, the changes of the surface bandgap and the surface band structure are highly connected with the changes in the electrical properties  due to halogen doping or gas exposure. As a result, mapping these changes not only in the bulk but also in the surface of the studied materials is worth mapping.To develop better SnO2 the hybrid functional PBE0 was employed. The bandgap value of the undoped surface is computed at 2.5 eV, in a good agreement with similar DFT works27. The smaller bandgap value compared to the bulk is attributed to the dangling bongs of the surface which create new states, responsible for this small reduction at the bandgap. Interestingly, in this high energy plane the bandgap value is decreased in all the halogen doping cases , (101) and (200) facets. These peaks agree well with the reported peaks of the tetragonal rutile structure of SnO228. Using Bragg’s law, the lattice parameters are determined, whereas with Scherrer’s equation the crystalline size of the samples. The lattice parameters were predicted according to the simulated peaks for each of the XRD spectra of the halogen doped structures. As it can be seen from the XRD, chlorine doped SnO2 exhibits the highest crystallinity while iodine doped SnO2 the lowest. Halogen doping produces shifts in all the facets, especially near 37.5 degrees. The lattice parameters where determined according to the shifted angles of each spectrum. The volume of Br:SnO2 is reduced in comparison to the undoped and to the relevent DFT result. This is because in the actual experimental conditions, intrinsic defects such as oxygen vacancies and tin interstitials are affected during the doping process. Consequently, the experimental results may vary from simulations. The results are presented in Table 2 the average crystallite size is decreased. The reduction of the grain size to the nanoscale is one of the most efficient methods to enhance the response of the gas sensor. The thickness of the depletion layer that encapsulates the grains is constantly changing when the gas is inserted due to oxidation–reduction reactions29.To investigate the crystallinity of SnOXRD Fig.  was empl2 have different values than those calculated with DFT. This is a common observation and it is associated with the intrinsic defects that highly affect the structural properties of the samples as well as the known limitations of the DFT. However, by applying DFT calculations, we can arrive at a good estimation and possibly reveal a trend of the effect of the addition of dopants in SnO2.It is observed that the lattice constants for the undoped and halogen doped SnO2 while Fig. 2 the roughness is predicted at 5.98 nm while it is 8.23 nm, 1.20 nm, 2.96 nm and 0.58 nm for F, Cl, Br and I respectively. Specifically with F doping, the roughness is increased compared to the undoped. The increase was not so sharp compared to the other halogens. We believe this is due to the radius of fluorine, which is close to oxygens. As a result, the incorporation of fluorine will not significantly change the structural properties, compared to the other halogens. This small reduction in roughness is possibly attributed to the incorporation of fluorine atoms in interstitial sites but still, further investigation is needed. The large decrease in the RMS roughness in the case of Cl, Br and I doped samples indicates that the dopant precursor salt is also incorporated inside the ripples thus filling the gaps between them. The morphology of the pristine and halogen doped samples are highly connected to the gas sensing properties of the materials as different roughness indicates changes in the active area which impacts on the current path and the depletion region. Furthermore, different surface is highly connected to the distribution of the Pt nanoparticles which affects the catalytic activity on the sample30. SEM images  deposited on the transparent bottom electrode. The bandgap reduction can also be beneficial for the response in gas sensors. Specifically, reduced bandgap is translated in easier transition of an electron from the valence band to the conduction band. So it is possible that the reduce bandgap can help the capture of electrons from the adsorbed oxygen species and also can help the transition back to the conduction band after the gas sensing reaction between the oxygens and the target gas.For the investigation of the bandgap changes of our samples, the optical properties are probed through the Ultraviolet–Visible (UV–Vis) spectroscopy. As it is presented in Fig. 2 sample, two peaks can be seen at 688.3 and 684.4 ± 0.1 eV attributed to F-Sn–O bonds and F- adsorbed on the surface, respectively35. This was also the case for the Cl 2p region for the Cl doped samples as shown in Fig. 2 surface. As a result, the experimental results are in a good agreement with the DFT simulations which use 1.38% dopant.Changes in composition upon doping are also investigated by using X-ray photoelectron spectroscopy (XPS) measurements. Moreover, XPS is an sensitive and accurate method to experimentally reveal if the halogen doping is achieved and at what quantities the dopants are inserted. Figure 2 samples. Considering the work function (WF), as taken from the high BE cut-off, for the pristine SnO2 sample, is 4.1 ± 0.1 eV36 and a slight decrease, up to 3.9 ± 0.1 eV, as the atomic number of the halogen increases37. This decrease in the WF indicates the n-type doping character of the halogen incorporation within the SnO2 which can contribute to enhanced electron conductivity. The VBM for all the samples is measured from the intersection of the Valence Band cut-off with the background and is 3.5 ± 0.1 eV38. The shoulder present around 2.8 eV is due to gap states induced by the lone pair Sn 5 s states. Compared to the DOS calculations in Fig. In Fig. 2 devices, the initial resistance values of the prepared SnO2 samples at different operation temperatures were determined. As it is shown in every examined case in Fig. 2 increases with temperature. The reason for this observation, is the ability of SnO2 to adsorb oxygen molecules with the increasing temperature. Considering that the chemisorbed atomic oxygens release electrons when the hydrogen gas is introduced, this can impact the sensing characteristics of SnO2. The present results agree with similar studies with Chemical Vapour Deposition (CVD) SnO2 and other similar sol–gel thin films8,39. From Fig. 2 samples, when the temperature returns to the initial point, the resistance changes compared to the initial value. This can be attributed to the kinetics of the dopants due to the variation of the temperature or the structural changes occurring. This can be considered as a disadvantage of the halogen doping compared to the undoped, as it is seen that every thermal cycle produces different results.To investigate the effect of temperature to the electrical properties of halogen doped SnO2 upon different hydrogen concentration was also investigated. Figures 2 sample increases its conductivity when the inserted gas is increased. This result agrees well with previous experimental studies40. From the present experimental results it is seen that halogen doping highly improves the response of tin dioxide especially in the case of Cl:SnO2 achieving the highest response in room temperature. This can be attributed to the reduced grain size of the surface as well as the reduced bandgap value. Furthermore, it is possible that the gap states that were created due to halogen doping might work as traps for the charge carriers and thus improving the response of the sensor. These results are summarized in Table 2 thin films is as follows: when we expose the surface of doped SnO2 to air ambient, the oxygen species will be absorbed, while when the surface is in a H2 gas environment there is a reduction of the exposure gas by the adsorption of oxygen molecules on the surface which this will increase the conductivity upon exposure. Depending on the operating temperature, the adsorbed oxygen species will capture electrons from the nanocrystalline halogen doped SnO2 thin films surface and become negatively charged which will increase the depletion region and therefore increase the resistivity39. From our research we noticed that at higher doping concentrations (as for example for 700 μl dopant in 700 μl SnO2) the current voltage measurements remain un-changed with the hydrogen insertion. We believe that this happens because when the halogen dopants are in higher concentrations, they tend to sit in oxygen vacancies sites. The reduction of oxygen vacancies is translated to reduction in adsorbed oxygens and thus the response of the sample is significantly reduced.The response of the fabricated sensors based on the halogen doped and undoped SnOFrom the presented results it can be seen that at low concentrations, halogen doping is beneficial for improving the response towards hydrogen gas. At higher concentrations, fluorine doping is seen to reduce its performance compared to the undoped sample. From our understanding this could be happening because at high gas concentrations hydrogen molecules possibly change the amount of surface F as they interact with it. By changing the number of surface F atoms it is possible that the number of active sites is reduced for the sensing reaction to take place, and thus the response is reduced. Our proposed mechanism for the improvement of the response towards hydrogen is as follows: It is possible that halogen doping increases the surface oxygen vacancies which work as active sites for adsorbed oxygen from air and this enhances the response of the sensor. Moreover, it is possible that the halogen molecules of the surface can be themselves active sites and interact with the inserted hydrogen molecules. Apart from the oxygen vacancies, other intrinsic defects possibly affect the performance of the gas sensor but it is not in the scope of this paper to investigate this phenomenon.2 devices is comparable to other reported sensors which operate at higher temperatures. Pippara et al.41 fabricated an SnO2 gas sensor doped with polyaniline and palladium that operated at room temperature and had a maximum of response equal to 540%. This result was achieved at 400 ppm. Compared to the Cl:SnO2 device, this result is better for low concentrations. However, at high gas concentrations the chlorine doping is more beneficial. Furthermore, doping with palladium is of higher cost compared to doping with chlorine or the other halogens. A similar undoped SnO2 sensor was fabricated from Tounier and Pijolat42 were they predicted that at 500 ppm the response of SnO2 reaches a value of 170% at operating temperature of 500 °C. This result was better compared to all the halogen doped cases examined in this paper except from the chlorine doping which still achieves higher sensitivity. Kadhim and Hassan43 fabricated an undoped SnO2 gas sensor which performed with a response of 600% at room temperature for 1000 ppm of H2. Although this performance is better compared to the undoped that is fabricated in this work, still the Cl:SnO2 shows better results. From all the above, it is seen that halogen doping and especially chlorine is a promising and low-cost method to fabricate portable devices that work beneficially at room temperature.The response of halogen doped SnO2 with hydrogen both from theoretical and experimental point of view is extensively investigated. DFT is used to investigate the changes in the structural, thermodynamical, and electronic properties due to halogen doping. It was found that halogen doping creates gap states that are beneficial for the adsorption of oxygen and hydrogen which are responsible for the change of the resistance of the sample. The incorporation of halogens is most probably occurred in substitutional positions while the iodine requires a higher amount of energy to be inserted in the structure. Regarding the experimental part, low-cost and easy-to-fabricate devices are created. Halogen doping is an easy method to enhance the response of SnO2 device in room temperature conditions. The Cl:SnO2 sensors show better response at every gas concentration at room temperature. The results towards H2 are comparable to the results of SnO2 in much higher operating temperatures. This type of enhancement in room temperature conditions is reported for the first time and can be practically used for the detection of dangerous gases. Using advanced characterization techniques we found that halogens reduce both the bandgap and the work function of SnO2. Through these experiments it was found that many or the electronic and optical characteristics are improved due to halogen doping; we argue that this improvement could be beneficial for other applications such as hydrogen production or photovoltaics. Although this work preliminary studies the properties of halogen doping as well as the response towards hydrogen, further experiments are required to investigate the other parameters of the gas sensors as well as the exposure to other gases apart hydrogen.In this paper the interaction of halogen doped SnOSupplementary Information.


Temperature elevation due to global warming increases the risks of dehydration, which can induce heat-related illness. Proper rehydration with appropriate amounts of water and electrolytes is essential to aid body fluid homeostasis. Wearable sweat sensors which can monitor both the sweat rate and sweat electrolyte concentration may be an effective tool for determining appropriate rehydration. Here, we developed a novel potentially wearable sensor that can monitor both the local sweat rate and sweat electrolyte concentration continuously. The new device includes a system with a short microfluidic pathway that guides the sweat appearing on the skin to a small space in the device to form a quantifiable droplet. The sweat rate is assessed from the time for the droplet to appear and droplet volume, while an integrated electric sensor detects the sodium chloride concentration in each sweat droplet. We demonstrated that this new device could record both the flow rates of artificial sweat and its sodium chloride concentration in ranges of human sweating with an accuracy within ±10%. This is equivalent to the accuracy of commercially available sweat rate meters and sweat ion sensors. The present study provides a new perspective for the design of wearable sensors that can continuously monitor sweat rates and sweat electrolyte concentrations for potential application to a healthcare device. Global warming is increasing the incidence of heat waves ,2 and heThe volume of fluid loss through sweating can be easily assessed by measuring body weight reduction after heat stress. However, assessing sweat electrolyte loss requires sensors attached to skin. To calculate the electrolyte loss, a sensor must be able to measure both the local sweat volume and the electrolyte concentration. Physiological studies have shown that the sweat sodium concentration varies widely across a range of sweat production  in whichSweat absorbent patches, the whole-body-washdown technique, and polymer bags/films have been used for evaluating sweat rates and sweat compositions during heat stress ,10. HoweElectrochemical measurement with an ion-selective electrode is a technique to implement electrochemical detection technology in a wearable device and continuously monitor the concentration of specific components of sweat in a form where the device is adhered to the skin. This approach is likely preferable, as it uses a small and fully integrated wearable device that can continuously monitor the concentration of a specific component of sweat through an external device such as a smartphone . On the The colorimetric method quantifies the concentration of a specific component in sweat by coloring the sweat in microfluidic channels using colorimetric reactions . This meTo overcome the problems in continuously measuring rates of fresh sweat and its chemical components, we developed an original sensor principle and verified its outcome. Our new device based on this principle includes a system with a short microfluidic pathway that guides sweat appearing on the skin to a small chamber to form a droplet—a quantifiable form—to assess sweat volume. It also includes an electric sensor to detect the sodium chloride concentration in each sweat droplet, allowing the continuous and simultaneous monitoring of both the sweat volume and sweat sodium chloride concentration.As shown in 2)) whose value corresponded to standard local sweat flow rate in exercise.A prototype device c,d was fGeneral-purpose numerical analysis software  was used to extract the time it took for the current peak to appear, and the peak values from the output current were acquired by the digital multimeter.Q [L/s] was estimated using the time for the peak current to appear, T [s], and the maximum volume of droplet, maxV [L], as follows:When the input flow rate of the artificial sweat was increased at a fixed sodium chloride concentration c,f–i, thmaxV = 82.5 nL). When the input flow rate was less than 0.1 µL/min, the estimated value was smaller than the reference value, as shown by the black dash line in V[t] reaches maxV and converts it to flow rate:inQ [L/s] is the input flow rate into the sensor, r [m] is the radius of the microchannel, θ [t] [rad] is the contact angle of the droplet at time t, D [m2/s] is the diffusion coefficient of water vapor, 0C is the water vapor concentration at the air–liquid interface of the droplet, ∞C is the water vapor concentration sufficiently far from the air–liquid interface of the droplet, ρ [kg/m3] is the density of water. The calculations were performed with r = 1.5 × 10−4 [m], θ[0] = 1 [deg], D = 2.91 × 10−5 [m2/s], 0C = 0.01743 [kg/m3], ∞C = 0.01177 [kg/m3], and ρ = 1.0 × 103 [kg/m3], respectively. The absence of data in this graph for flow rates of less than 0.02 µL/min indicates that no droplet is produced because the evaporation rate of the droplet is larger relative to the input flow rate. Considering these results, we assume that the evaporation of the droplets is suppressed by the effect of the sodium chloride solution suspended in the sweat model solution compared to the case where the droplets in the sensor are water droplets, and thus the error of the estimated input flow rate is reduced relative to the reference value. On the other hand, for input flow rates of 0.1 µL/min or higher, i.e., in cases where sweat production is relatively large, such as sweating in hot conditions, the effect of evaporation was hardly observed, and the error of the estimated value of the input flow rate with respect to the reference value was kept within ±10% of the reading. This is a sufficient and reasonable error in comparison to commercially available sweat meters for assessing thermal sweat production [2) [2 will provide sufficient measurement accuracy for the wearable measurement.Here, V was set so that the estimated value was closest to the reference value (oduction . In addition [2) , even inWe believe that the proposed device can be used to establish a proper hydration strategy for people during exercise or heat exposure in hot climates. In addition, by developing electrodes that are more selective and specific to other molecules or ions, it could also be utilized as a healthcare device for monitoring several biomarkers in sweat such as glucose, lactate acid, and alcohol. Further study is required to develop a structure to reduce the effect of sweat evaporation in the sensor so that a small amount of sweat can be measured. Finally, a proof-of-concept study in human participants is obligatory in the future.We proposed a new concept for a potentially wearable sweat sensor to continuously measure the flow rate of sweat and its electrolyte concentration. We also evaluated the accuracy of a prototype sensor and found that it was acceptable for monitoring both the sweat rate and sweat’s sodium chloride concentration in wide ranges of volume and concentration, respectively. Our results indicate that the proposed sensor is potentially viable for monitoring sweat flow rates and electrolyte concentrations in actual human sweating. They also shed light on the design of wearable sensors for monitoring sweat volume and the concentration of specific components in sweat.


Magnetoresistance measurements in amorphous NbN nanowires show that transport current affects their negative magnetoresistance (nMR) in a manner qualitatively similar to temperature. In particular, the current suppresses the nMR and, beyond a certain level it eliminates the effect altogether. As the temperature dependence of the nMR effect is more pronounced at low currents, similarly the current dependence of the effect is more pronounced at low temperatures. These results are discussed in terms of the phenomenological model which attributes the nMR to the interplay between the resistance originating from the rate of phase slips via the Josephson relation and the Ohmic contribution from quasiparticles charge imbalance that accompany fluctuations of the order parameter in the nanowire. Each fluctuation is associated with a phase slip of 9 found in a wide variety of 1D superconductors21. A phenomenological model by Arutyunov8 explains the nMR as originating from a competition between two mechanisms: thermodynamic fluctuations of the order parameter and quasiparticles (qp) charge imbalance which accompanies each phase slip event. The first process provides the conventional positive magnetoresistance, while the second one gives negative contribution as the quasiparticle charge imbalance length decreases with field. In the range of low magnetic fields, the first process is not significantly affected, while the second one is effectively suppressed, contributing to the experimentally observed nMR. Apparently, both processes depend not only on the magnetic field but also on temperature and the transport current. Yet, while most of the published experimental results describe the temperature dependence of the nMR measured at a certain constant current21 data on the effect of the current on the nMR is scarce17. In the present study we experimentally explore the influence of transport current on the nMR in amorphous quasi-1D NbN wires. We observe that the current suppresses the nMR effect and, above a certain level it eliminates the effect completely. As the temperature affects the nMR in a qualitatively similar way, the current dependence of the nMR effect is more pronounced at low temperatures. These results are discussed in the framework of the Arutyunov's phenomenological model8.Extensive studies have shown that thermal and quantum fluctuations in superconducting nanowires give rise to a non-vanishing resistance below the transition point, down to very low temperatures23. The sputtering was done at a rate of 0.075 Å per second with a 99.95% pure Nb target in a gas mixture of Nitrogen (8%) and Argon with a total pressure of 5 nm films of NbN were deposited on a mentclass2pt{minim2) are of the order of the zero-temperature coherence length in bulk NbN (ξ0 = 6 nm).Figure c. Figure Figure A more comprehensive description of the dependence of the size of the nMR effect on temperature and current, is presented in the 3-dimensional plot shown in Fig. 2, taking into account the effect of both temperature and current. According to this theory, the time average voltage generated by thermally activated phase slips (TAPS) is given by24:–10 s. The temperature dependence of 0 = 4 nm for NbN films26, one obtains for E0 a value which is an order of magnitude higher, suggesting that the experimental value for the energy barrier is lower than the theoretically predicted one. We note that similar deviations were reported in previous publications, see e.g. Ref27, calling for further investigations. As suggested in that reference, the deviation may be associated with a smaller effective value of A. We also note that the critical field for a film is larger than Bc(0) of the bulk by a factor of λ/d; our film is 5 nm thick whereas the London penetration depth is ~ 150 nm.To verify the fluctuation origin of the broadening transition, we fitted the data of Fig. same parameters, we fit Eq. .The magnetoresistance behavior of a superconducting nanowire is, thus, governed by two competing processes: The rate of phase slips, The phenomenological model presented by ArutyunovThe effect of bias current on the charge imbalance relaxation length is qualitatively similar to that of a magnetic field8).The bias current decreases vs. I one may expect to observe a range of currents in which dR/dI < 0. However, as shown in Fig. 34, which can be interpreted as inducing negative differential resistance. However, our wires show neither the resistive transition anomaly nor negative differential resistance.This expression is obtained by substituting entclass1pt{minimaThe fast increase of ent Fig. b. In thec and in order to fit the model to our data we need an expression for The effect of temperature is qualitatively similar to that of the current; as temperature increases, The effect of transport current on the magnetoresistance can be qualitatively explained within the framework of the phenomenological model of Arutyunov, which attributes the magnetoresistance to the interplay between the resistance resulting from the rate of fluctuations via the Josephson relation, and an Ohmic contribution from the quasi-normal regions that accompany the fluctuation. Both temperature and current strongly increase the rate of fluctuations, thus suppress the nMR. Similar to the effect of the magnetic field, the current also reduces the quasiparticle charge imbalance length, thus one would expect to observe a non-monotonic behavior of the resistance not only with respect to magnetic field but also with respect to the current. However, the experiment shows no such a behavior; the resistance always increases monotonically with the current. The difference between the behavior with respect to the field and current can be attributed to the effect of the field on the fluctuation rate which occurs only through the dependence of the gap on the magnetic field, as opposed to the current which enhances more strongly the fluctuations rate. As the temperature and current qualitatively affect the nMR in a similar way, the temperature dependence of the nMR effect is more pronounced at low currents. Similarly, the current dependence of the nMR is more pronounced at low temperatures.


Wagner Group in Mali.The interpretation of the Russian war of aggression against Ukraine as a “turning point” indicates that long-established parameters of securing peace in international politics will change. This article tentatively assesses consequences of this war for the agenda of international peacebuilding and for wider interventionist practices in contemporary violent conflict settings. It is argued that the ongoing war speeds up a preexisting phase of profound order transformation that will considerably change the ways in which states manage conflicts and attempt to secure lasting peace in the international system. The article outlines how ongoing transformations already affect—and will further affect— interventionism at different entangled scales, ranging from the global to the local. The contribution draws on recent studies of the rise and decline of global orders and interweaves them with insights from empirical peace and conflict research and critical studies of peacebuilding and interventions. It discusses the further decline of global cooperation in the wake of the Russian war against Ukraine, outlines the consequences of the rivalry between United Nations Security Council veto powers for the global agenda of peacebuilding and the conduct of peace operations, and illustrates the local consequences for specific intervention sites, in particular the negative impact of the employment of the Russian  The interpretation of the Russian war of aggression against Ukraine as a “turning point” not only for the European peace and security order but also for global politics indicates that long-established parameters of securing peace in international politics will change. This contribution tentatively—and selectively—assesses consequences of this war for the agenda of international peacebuilding and for wider interventionist practices in contemporary violent conflict settings, often framed as counter-terrorism and stabilization operations. We understand these interventions as world-ordering practices, justified with references to existing or presumed norms of international order  concludes the discussion.This forum piece contributes to a debate that seeks to highlight both the “messiness” of current transformations and to explore first trajectories of patchworked, rival and declining forms of interventionism that are emerging today. The contribution is structured as follows: The next section (Sect. 2) deals with the enhanced rivalry among the veto powers within the United Nations Security Council (UNSC). This highlights the further demise of the “liberal” international order and the decline of global cooperation in the wake of the Russian war against Ukraine. The following section (Sect. 3) discusses consequences of this rivalry for the global agenda of peacebuilding and the conduct of peace operations. Section 4 turns to local consequences for specific intervention sites, in particular the negative impact of the employment of the Russian The war in Ukraine fuels debates about the crisis of the international  order , conducts a war of aggression—or where such a veto power seeks to protect another regime that is accused of a brutal war against its own civilians as in the Syrian case.The Russian war against Ukraine has further exacerbated the increasing rivalry between Western powers and China and Russia within the United Nations Security Council that already manifested in the frequency and continuity of vetoes cast by Russia and partly China in the Syria crisis Niemann . The UniThe inability of the UN Secretary-General António Guterres to mediate in the Russian war against Ukraine and of the UNSC to deal appropriately with the situation has caused a lot of frustration. The Ukrainian President Zelenskyy expressed this in his speech to the UNSC in April 2022 in light of evidence of Russian atrocities in Bucha: “How is this different from what the ISIS terrorists were doing? (…) Except that it is done by a permanent member of the United Nations Security Council. (…) The U.N. system must be reformed immediately so that the right of veto is not a right to kill.” The only logical alternative would be to concede the council’s irrelevance and “dissolve yourself altogether.”1this situation and that it should not be reduced to the UNSC’s (in)ability to pass resolutions , conducted military interventions without a UNSC mandate (Kosovo 1999), transgressed their mandate in the Libyan case in 2011 with the aim of regime change, destabilized whole regions with their interventions (Middle East) with enduring devastating effects Yahya , and stiTripathi  observesSuch “double standards” by the West have been stigmatized by Russia for a long time, even before President Putin came to power Allison . This maThe military interventions and wars in which the P5 powers have been involved since the 1990s have thus further exacerbated a basic conflict between the Western powers and Russia (and to some extent China) about who makes the rules in global politics, about their legitimation in interpreting international law, and employing the use of force. The persistent claims of Western powers to use military force for good and reasonable purposes only is definitely not shared as credible justification by others.While the prior section has sketched out the paralysis of the UNSC and the mutual blaming of Western Permanent Five members and Russia and China of grave breaches of international law, the following section will discuss to what extent the global agenda of  peacebuilding will plausibly be affected by the described enhanced rivalry. The liberal “peacebuilding consensus” Richmond , that isThe war in Ukraine has exacerbated this pre-existing crisis of liberal interventionism, with parallel processes pointing to a further decline of liberal interventionism, at least in the field of UN peacekeeping, as well as to patterns of rival ordering attempts, but also new forms of cooperation.As to the first process, peace operations deployed by the United Nations have been in decline since 2014, with the last new UN peacekeeping operation launched in 2014. This decline in relevance of multilateral peace operations is likely to continue in a stalled UN Security Council. In the near future, observers do not expect the UN to be “mandated to launch robust, large, and costly new UN peacekeeping operations or reform processes”  practices and “operate both within and outside the liberal peace perspective”  Training Mission (EUTM), and the G5 Sahel Joint Force have been active. Mali exemplifies the growing entanglement of the international peacekeeping and the counter-terrorism regimes under the paradigm of “stabilization” , the French counter-terrorism operations The operational proximity of Russian PMCs, accused of human rights violations, to UN peacekeepers can have a negative impact on the local perception of UN troops, as is indicated for the case of the United Nations Multidimensional Integrated Stabilization Mission in the Central African Republic  are also indicators of states “by-passing” the rigid UN system, attempting to coordinate international policies and partly develop their own procedures and self-legitimation strategies Gronau .As a second trajectory, “democracy vs. autocracy” grand narratives have been fuelled again by the Ukraine war and could be further revived in the future. The idea of a “Concert of Democracies” that should enjoy privileges in global governance, including the self-mandating of the use of force, was discussed in liberal and neo-conservative circles in the US more than a decade ago Geis . US Presfundamentally is a question that requires more systematic research (Turner and Kühn Finally, new and emerging cooperation patterns in multi-intervention sites such as Mali point to the need to further question binary distinctions between “Western” and “non-Western” actors in interventions. Whether interventionist practices differ


We present a case report and a literature review of the awake craniotomy procedure for mass resection, with emphasis on the historical aspects, anatomical and surgical considerations, and, uniquely, a patient’s experience undergoing this procedure. This procedure is a safe and effective method for lesion resection when working in and around eloquent brain. We have described our process of guiding a patient through an awake craniotomy procedure and detailed the patient's experience in this study. We also conducted a systematic literature review of studies involving awake craniotomy over three years, 2018-2021. Lastly, we compared the methodology used by our institution and the current mostly used methods within the neurosurgical community. Several studies were identified using PubMed and Google Scholar. Awake craniotomy is a safe and effective method of achieving a high rate of resection of lesions located in and around the eloquent cortex with a low degree of postoperative neurological deficit. No surgery is as famous as awake craniotomy, which we will explore both from a literary review and from a patient’s direct experience. Many previous studies have demonstrated that the extent of resection (both of high- and low-grade gliomas) portend increased survival rates in patients. Thus, when lesions are located within the eloquent cortex, awake craniotomy has been shown to be the gold standard . The terThis procedure is associated with a greater extent of resection and a lower incidence of postoperative neurological deficits . InitialAwake craniotomy is utilized in the resection of lesions located in proximity or within the eloquent brain cortex and finds the most utility in both epilepsy surgery and tumor resection. The procedure allows for intraoperative, real-time identification of eloquent areas to avoid compromise of the patient’s neurological function. Two anesthetic methods used to complete the procedure include monitored anesthesia care (MAC) and asleep-awake-asleep techniques. Though the former has been found to be associated with a lower risk of surgical failure and shorter procedure time, MAC is also the authors’ preferred method of utilizing anesthesia during the procedure . FurtherAppropriate patient selection is paramount in assessing who will benefit from an awake craniotomy procedure. The patient’s ability to participate and cooperate with commands is a prerequisite to a successful operation. Contraindications to surgery include mental confusion, poor compliance, and inability to concentrate . At leasAlthough comprehensive reviews have been written on the technique of awake craniotomy, this study will focus on both the authors’ and, more importantly, the patient’s experience of awake craniotomy at a single institution in the United States.We will discuss a single patient’s comprehensive experience from discussing his planned procedure with his family, the pre-procedural anxiety, the preoperative scalp block process, and his experience during the procedure in this section.Our patient is a 50-year-old right-handed male who presented with a first-time complex seizure and episode of emesis. He had also endorsed a month-long history of intermittent expressive aphasia and personality changes. The patient received a computed tomography (CT) of his head at an outside facility demonstrating an 18 mm left frontal ring-enhancing lesion with associated vasogenic edema and was transferred to our facility for evaluation by our neurosurgical service. He reported a benign medical history, though endorsed a maternal family history of pheochromocytoma, and a deceased brother secondary to an unknown brain lesion. The patient was neurologically intact on examination, receiving high-dose steroids prior to his evaluation by our neurosurgical service. The patient had an unremarkable chest, abdomen, and pelvis CT with IV contrast and computed tomography angiogram (CTA) of his head and neck. Following admission, several discussions took place between the patient and our neurosurgical service. We believed due to the proximity of the pars triangularis of the inferior frontal gyrus (associated with Broca’s area), an awake craniotomy operation would be the best neurosurgical option for the patient.Pre-procedural scalp blockProper analgesia is imperative to the patient’s experience during awake craniotomy. Sensory innervation to the face and scalp is supplied by several important branches that must be properly anesthetized prior to the craniotomy. Important innervation is supplied by the supraorbital and supratrochlear nerves above the orbit Figure , Panel AAwake craniotomy procedureThe patient was brought to the preoperative area prior to surgery and given 1 mg sublingual Ativan for anxiety. The hair was clipped around the planned incision site, and areas of nerve block were marked and prepped. Topical 5% Lidocaine was applied to the scalp sites prior to performing nerve blocks. We preferred a mixture of 0.5% Lidocaine with 1:200,000 epinephrine and 1% Bupivacaine with 1:200,000 epinephrine. This solution was used to perform blocks at the following sites: supraorbital/supratrochlear nerve, zygomaticotemporal nerve, auriculotemporal nerve, lesser occipital nerve, and greater occipital nerve. Ultrasound was used to identify the superficial temporal artery and the occipital artery, thus allowing us to avoid their incorporation during the scalp blocks within the temporal and occipital areas. The patient rested comfortably in the preoperative area for approximately two hours prior to being taken to the operating room (OR).The patient was brought into the OR, and a standard time-out was performed. The patient was positioned on the OR table with the horseshoe head holder and left side up. All pressure points were carefully padded. A warm blanket was placed on top of the patient to keep him comfortable. The patient's head was gently turned to expose the left frontotemporal region and the planned incision. Signs were posted in the OR stating "Discretion, patient awake." The incision line was injected with a local anesthetic of 1% Lidocaine with epinephrine. A sterile sharp needle was used to test the effectiveness of the regional nerve block and incisional local anesthetic. The patient was noted to have no pain subjectively or any change in vital signs indicative of pain or discomfort. Next, we registered the intracranial stealth navigation system . Vital structures including the tumor borders were identified and mapped out. The planned craniotomy along with the trajectory for entry and target was then outlined. The incision was re-marked. A final time-out was held with nursing staff, anesthesia, and neurosurgery to confirm the correct patient, the correct site of surgery, the correct procedure, the proper positioning, padding of the patient, and line access as agreed upon by nursing and anesthesia staff. A 10/10 drape was placed on the forehead of the patient.The patient was told that he would be informed prior to every step, so there would not be any surprises for him. Frequent checks occurred to ensure that the patient was comfortable and free of anxiety. Anesthesia stood ready to temporarily sedate the patient for parts of the surgery, at our request. Next, the patient was prepped and draped in a standard sterile fashion. A member of the team was making constant communication with the patient under the drapes but away from the sterile field. A standard bone flap was turned to expose the dura in the desired operative corridor. A tuberculin syringe was then used to inject 0.5% Lidocaine with epinephrine between the two layers of the dura, parallel to the middle meningeal artery and branches. An ultrasound probe was then used to confirm the location of the mass prior to making the dural opening. The dura was then opened in a cruciate fashion using a #11 blade and dural scissors. The leaflets were reflected away. A strip electrode was then placed in the subdural space posteriorly to perform direct cortical electroencephalogram (EEG) monitoring; two electrodes were also placed by the neurophysiology tech in the patient's face and hands to monitor seizure-associated electromyography (EMG) changes.The location of the mass was visualized with ultrasound to plan the corticectomy. Anesthesia staff were then asked to make the patient more awake by weaning down the IV anesthetics. A team member was engaged in direct communication with the patient, and he was asked to perform simple tasks including sticking his tongue out, counting backward from 20, and doing simple math. Cortical stimulation was performed using a probe for language area mapping. No speech arrest, paraphasia, or hesitations were noted. We determined that the area of planned corticectomy did not stimulate any functional significance. The surgical microscope was brought into the surgical field, and the mass was resected in a standard microneurosurgical fashion. Following the procedure, the patient’s speech and motor exam were again tested, and no new deficits were appreciated. He was transferred back to an ICU bed. The patient was able to have a full conversation with the neurosurgery team after the drapes were taken off. Pupils were noted to be 3-2 mm briskly reactive bilaterally. The patient’s wife was updated in real-time in the OR by the attending neurosurgeon and the neurosurgery team; the patient was also able to speak with his wife from the OR. Postoperative care proceeded without any complications.Post-procedural patient experienceOur patient successfully underwent an awake craniotomy procedure for mass resection without any neurological deficit or complications. The patient was interviewed on postoperative day number one by our neurosurgical team to determine the patient's experience after undergoing awake craniotomy. We sought to examine the patient’s level of anxiety and discomfort, both psychologically and physically, throughout the periprocedural period and postoperatively. The following section demonstrates our questions and the patient’s responses.What was it like to consider the option of having an awake craniotomy procedure?The patient expressed that he was pleased with his decision to go forward with an awake procedure as opposed to the alternative of surgery under general anesthesia. He expressed surprise and gratitude at the level of attention paid to him throughout the procedure from the anesthesia, neurosurgical, neuromonitoring, and OR teams. He was very aware throughout the process that a large amount of personnel and equipment were arranged in such a way as to give him the best outcome.What was the process like to discuss with family?The patient endorsed that his family was worried and did have some reservations regarding the procedure. They expressed concern surrounding the notion of whether the patient would still be himself following surgery. They wondered how extensive the recovery process would be and how long it would take. The patient and his family worried about continued seizures especially in the setting of the patient’s occupation as a truck driver.What was the process of the scalp block like and the ensuing surgical procedure once in the operating room?Prior to the procedure, we discussed with the patient that previous patients had reported the sounds experienced during the procedure were the most unsettling aspect. The patient corroborated this. During the initial scalp block injections and throughout the craniotomy, the patient stated that he could hear the anesthetic being injected into his scalp and described this sound as “ice cracking.” Additionally, the worst part was the initial scalp block injections, which felt to be cold. Once the patient entered the OR, he endorsed being able to hear all conversations around him. The procedure appeared to proceed quickly to the patient. He felt the addition of a person by his side, talking to him throughout the procedure, made him feel not alone. The patient felt that this step in the procedure was important to him. He also always felt that he knew what was happening due to the constant communication from the neurosurgeons as well as the reassurance that things were proceeding according to plan. He felt that the procedure would have been difficult if he had to stare at a wall, wondering about the progress of the procedure.A variety of authors used different methods to measure patients’ psychological experiences while undergoing awake craniotomy. These include the use of interpretative phenomenological analysis (IPA) to explore how people made sense of the awake craniotomy experience , use of Attempts have been made to explain the participants trying to make sense of their experience - also known as "double hermeneutic" in phenomenological studies . ZemmourThe psychology and patient’s experience are best summarized by the three superordinate themes: use of self-preservation strategies prior to and during awake craniotomy, a bizarre yet pleasant operation experience, and the need for more concrete information prior to surgery. Each of the three superordinate themes appeared to be embedded in a core theme of having a good relationship with the neurosurgeon .Even though previous studies reported awake craniotomy is well tolerated and has great patient satisfaction, anxiety had been reported as the most common psychological phenomenon . AnxietySimilarly, an interesting case study of an 11-year-old female patient with a tumor in her right motor cortex  had a simulated surgical experience by replicating a theatrical setting in which the patient dressed in a theater attire, brought into the OR in a trolley, transferred onto the OR bed, and placed in the exact position as the actual surgery . The thePrior to the awake craniotomy, the patient's expectations of the procedure compared to the actual event are not coordinated resulting in the feeling of having a weird or bizarre experience perioperatively. Bajunaid and Ajlan found that most of their patients had auditory recollections from the operation and no pain perception, and none of the patients reported that awake craniotomy was more difficult than anticipated . HoweverAnesthesiologists play a crucial role in the patient's experience of awake craniotomy. Ma and Uejima's case study of a 32-year-old male with a past medical history of PTSD involved a neuroanesthesiologist preoperatively for an awake craniotomy in preparation for each step of the operation. A focus was placed on when to ask questions to get a sense of control and to be able to communicate during symptomatic distress . ChildreThe need for more concrete information prior to surgery was presented by the patients due to the inability to relay information back to family and friends and understand the operation procedures. However, despite the dissatisfaction, it was hypothesized that failure to seek out information was due to patients utilizing their relationship with the neurosurgeon to compensate for the lack of concrete information . PottersFletcher et al. believed that patients utilized their self-preservation (based on their relationship with the neurosurgeon) by entrusting the neurosurgeon of giving the responsibility to decide whether to go ahead with the procedure and avoid facing the implications of the decision themselves . An exteA traumatic experience during an awake craniotomy is prejudicial to the outcome of the quality of life . Riquin More studies are needed to understand the psychology of the patient’s experience during awake craniotomy. Not only is the procedure safe and effective, but we also must consider the patient’s psychological aspect to mitigate the mental stress before, during, and after the procedure. Studies so far demonstrated that a good relationship between the patient and the neurosurgeon/surgical team is crucial to the patient’s experience ,24. MultLimitationThis review included a limited number of studies. Additionally, our study only included one patient that relied on that patient’s subjective experience. Objective data/questionnaires were not included in our study.Awake craniotomy is a safe and effective method for achieving a high rate of resection of lesions located in and around the eloquent cortex with a low degree of postoperative neurological deficit. A review of this neurosurgical team’s experience is highlighted with a focus on both the authors and, more importantly, the patient’s experience of awake craniotomy at a single institution in the United States.