Finally, the minimum contact resistance of the intermediate joint is 7.05 μΩ, which is 43% lower than that of the aluminothermic welded joint, and the tensile strength is close to that of the welded joint, with a maximum of 7174 N.With the increasing use of underground cables, the quantity and quality of intermediate joints demanded are also increasing. The quality of the traditional crimping intermediate joint is easily affected by the actual process of the operator, which may lead to the heating of the crimping part of the wire core, affecting the insulation performance of the cable, and finally causing the joint to break. However, aluminothermic reactive technology has some problems, such as a high welding temperature and an uncontrollable reaction. In order to solve these problems, according to the brazing principle and microalloying method, the optimal content of In in Sn-1.5Cu-based solder was explored, and then the connection of the middle joint of a 10 kV cable was completed using a connecting die and electrical connection process. The contact resistance and tensile strength of the joint were tested to verify the feasibility of this method. The results show that the maximum conductivity of the solder with 3.8% and 5% In content can reach 3.236 × 10 With the gradual promotion of urbanization in various places, the proportion of underground cable laying is gradually increasing. Cross-linked polyethylene (XLPE) insulated cable has been widely used in urban power grids because of its convenience and stability . XLPE caIn order to reduce the line faults caused by cable joints, scholars from various countries have studied and analyzed the characteristics of cables, such as detecting the fault in a cable joint and locating it , or studThe current research shows that the causes of cable failure are more concentrated at the connection of intermediate joints. Due to the influence of construction technology on the quality of traditional crimping joints, such as low terminal fitting accuracy, uneven manual force, and unsmooth edges and corners of joints, etc., it is easy to cause a local temperature increase ,13,14. SRecently, Jongwuttanaruk et al.  reportedDue to the health and environmental problems of traditional lead–tin solder, tin-based lead-free solder has been introduced. The new elements added to the tin-based system should meet some basic requirements ,20,21, sBrazing technology can be applied in different application scenarios, and it is particularly important to produce a kind of brazing filler metal that meets the relevant conditions. In order to obtain a better ratio of solder, we first tested and analyzed the Sn-1.5Cu binary alloy, adding different amounts of In to modify it, and then used the mold and explored the joint connection process to complete the production of intermediate joints. The tensile strength and contact resistance of the joint were tested, and the mechanical and electrical properties of the aluminum hot fusion joint were compared and analyzed.According to the binary alloy phase diagram of Sn-Cu, the Sn-1.5Cu alloy material was prepared, and the thermal, electrical, mechanical, and interfacial properties were analyzed. By exploring the influence of In content on the properties of the substrate, excellent welding materials were selected. In the experiment, Sn-1.5Cu binary alloy was used as the basic material, and the pure Sn, Cu, and In particles of 99.99% metal elements were prepared by the laboratory. After calculating according to the percentage mass fraction, the corresponding metal elements were measured on an electronic scale and smelted in SY0002 melting furnace at 900 °C. KCL powder was added as a covering agent to isolate the air and reduce metal oxidation. During melting, the liquid metal needs to be fully stirred every other 15 min. After holding for 30 min, pour it into the mold and set it aside after solidification and cooling. This paper explores the effect of adding different amounts of In to Sn-1.5Cu-based solders, and the element composition of the alloy materials is shown in The melting point of lead-free solder is one of the important standards to measure the material technology. In this experiment, the melting temperature was measured with a NETZSCH STA449F3 differential scanning calorimeter, and the alloy sample tested was about 20 g. Before the test, the sample needs to be cleaned with acetone and ultrasonic, and the surface oxide is removed. Secondly, the alcohol is cleaned and dried with 600 mesh sandpaper and finally put into the equipment for measurement. The whole experimental process needs to be filled with protective gas. The heating range of the experimental equipment is controlled at 20 °C to 250 °C, and the heating rate is set at 10 °C/min.R is the measured resistance, S is the area of the surface electrode, and t is the electrode thickness.Electrical conductivity is an important parameter that affects current transmission. The electrical conductivity testing device made by ULVAC Company in Japan was used to measure the properties of metal materials by four-point probe method, and the samples were prepared into cylindrical samples with a diameter of 6 mm and a height of 10 mm. The device directly tests the resistivity of the tested sample, so it needs to be calculated according to the formula. The conductivity is the reciprocal of the resistivity, and the expression of the conductivity is as follows: where Tensile samples are usually cut from the product or blank and machined, and linetypes, bars, and casting patterns with constant cross-sectional area can be tested without machining. The interface performance is also the wettability, which is mainly reflected in the combination of solid and liquid after contact. The wettability is determined by the wetting angle and spreading area. Spreading wetting: at a certain temperature, the spreading process of liquid solder on a solid surface depends on the ability of breaking the oxide film of flux and the capillary force and fluidity of liquid metal to realize the welding process of liquid metal and solid. The surface free energy of solders with different contents or metal compositions is different. The surface free energy determines the surface tension, and the change in surface tension determines the wettability and spreading performance.The base material of the spreading wetting test was T3 copper, and its length, width, and height was 20 mm × 20 mm × 2 mm. L-2 flux of Guangdong Metal Research Institute of China was selected, JF-966C computer heating platform was used, and nitrogen was continuously put into the wetting test. The copper sheet was polished with sandpaper, cleaned with alcohol, and dried; 2.00 g ± 0.10 g solder was made into a spherical shape on the heating table, cooled, and ground to 1.80 g; under the protection of argon gas, the copper sheet was evenly smeared with flux, the solder ball was placed in the center of the copper sheet, and placed together on the heating table preheated at 280 °C; after waiting for the reaction, the surface was cleaned and photographed, image processing was carried out to calculate the spreading area, and the solder height was measured.S is the spread area of the solder, and H is the height of the solder. The expression of the spreading rate of the solder is as follows, where K: spreading rate; H: solder height after spreading (mm); and S: solder spreading area (mm2):2 (diameter of wire: 11.8 mm) cable. This section takes the actual connection situation of 10 kV cable as the object and designs different sizes of molds to complete the middle joint connection of 120 mmThe contact resistance is the main cause of the heating of the cable. when the contact resistance is reduced, the calorific value must be reduced. According to the electrical contact theory, when two contact elements come into contact, the seemingly smooth surface is actually uneven, and when the current passes through, it will always pass through the contact surface at the conductive spot, so the size of the contact surface determines the total resistance of the cable. At the same time, the electrical conductivity of the joint also reflects the ability of the solder to remove the oxide film of the conductor.At present, the method of measuring contact resistance is commonly used to measure resistance voltage. The experimental test platform, as shown in A joint size with excellent performance is obtained by testing and analyzing its electrical and mechanical properties. The influence of In content on the properties was analyzed, and the aluminothermic reactive welding joints were made and compared. From the test data, it is concluded that the brazing technology can be applied to the manufacture of cable intermediate joints, which is easier to control and safer than the brazing aluminothermic reaction.6Sn5 intermediate compounds and improve the tensile strength of the solder. When the content of In is 5%, the material has the maximum tensile strength of 53.18 Mpa. In has a positive effect on the improvement of electrical conductivity, but when a small amount of In is added, it will destroy the metal bonds in the basic solder and cannot take full advantage of the high conductivity of copper. The addition of In can significantly improve the wettability of solder, and the maximum wettability can reach 93.6%. The spread of the solder is shown in The melting point, tensile strength, electrical conductivity, and wettability of Sn-1.5Cu-XIn solder were tested according to the method described in the previous section, and the test results are shown in Because the electrical conductivity and strength values of Sn-1.5Cu-5In were slightly higher than those of 3.8% In solder, and the wettability was similar, the material was finally selected for the first stage of the process test. The wettability test of Sn-1.5Cu-5In was carried out at 230~280 °C and included three groups, as shown in As shown in In the process exploration, each joint was made three times, and the measurement result was the average. As shown in As shown in The electrical performance of welding at different temperatures is shown in From the above results and analysis, the joint fabrication parameters are determined as follows: welding temperature: 250 °C, end clearance: 1 mm, joint diameter: 16 mm, and joint length: 30 mm.2 specification cable, and designs the connection mold to complete the intermediate head connection in the following process order. (1) Strip off the insulating layer and semiconducting layer of the cable to expose the copper conductor; (2) polish the copper conductor and clean it with alcohol; (3) melt 300 g of solder at 270 °C, preheat the mold at 250 °C, and smear the flux on the surface of the wire core; (4) install the mold, adjust the end face of the wire core, and pour the liquid solder; and (5) cool, open the mold, and polish the joint. This section takes the actual connection of 10 kV cable as the object, according to the 120 mmAfter the welding process is determined in the previous section, the intermediate joint is made with Sn-1.5Cu-XIn  solder. Symmetrically select the connector and the surrounding 30 mm, measure the positive and negative access to each test three times, and take the average experimental data as shown in The tensile strength of intermediate joints with different In content is shown in Put the prepared joint sample into both ends of the fixture of the tension machine and set the drawing rate 2 mm/min. The tension curve of the aluminothermic reactive fusion joint and the brazed joint of 5% In is shown in 2) cable as the object, a better welding process was developed by adjusting the temperature, gap, diameter, and length. Based on this process, the joint fabrication of Sn-1.5Cu-XIn solder was completed. After testing the contact resistance and tensile strength of the joint, we arrive at the following main conclusions:(1)6 S/m. When the In content is 3.8%, the wettability spreading area is the largest. The value is 93.05 mm2, and the wettability is 93.6%.Solder properties: The alloy solder is based on the Sn-1.5Cu system. By adding In to modify it, we found that with the increase in In the melting point decreases from 227.6 °C to 220.7 °C. The tensile strength of solder increases and can reach 57.18 Mpa when the content of In is 5%. The electrical conductivity of the solder increases slowly when the In content is 3.8%, and the solder conductivity reaches the maximum value of 3.236 × 10(2)Joint manufacturing technology: In terms of joint size, we have studied a diameter range of 14 mm~18 mm, length range of 10 mm to 30 mm, welding temperature range of 230~280 °C, and welding gap of 0~4 mm. From the test results, the process is determined as follows: diameter: 16 mm, length: 30 mm, temperature: 250 °C, and welding gap: 1 mm.(3)Joint performance: The results show that the contact resistance of the joint decreases with the increase in In content, the contact resistance changes approximately linearly, and the minimum contact resistance is 7.05 μΩ when the In content is 5%. Compared with the aluminum hot-welded joint (12.39 μΩ), it has better electrical properties; the increase in In content in this range can improve the tensile strength of the joint, and the maximum tensile strength is 7174 N at 5%, which is close to 8797 N.In this paper, the application of Sn-1.5Cu-based solder in a cable intermediate joint was introduced in detail. We configured Sn-Cu-based solder and studied different amounts of In to modify it to obtain a better performing solder composition. Then, taking 10 kV (120 mmAt present, there are still great difficulties in manufacturing power cable joints in harsh environments, and the improper manufacturing of copper wire joints will bury serious hidden dangers in the transmission lines. In this paper, by comparing and testing the performance of the aluminothermic reactive fusion joint in the more mature market, the developed brazing method was shown to achieve an excellent connection effect in the cable core connection. In the follow-up, it is necessary to analyze and demonstrate the reliability of the long-term operation of the wire core joint.


With the increasing demand for high temperature-resistant heat insulation materials for hypersonic vehicles, carbon foam has been studied extensively, and its mechanical and thermal properties have been fully researched, but the oxidation behavior of carbon foams during service and the change in their properties after oxidation are rarely studied. This paper studied the relationship between both mechanical and thermal properties and oxidation degree of two kinds of foams, coal-based carbon foam and antioxidant coal-based carbon foam with chemical vapor deposition of SiC particles. The variation trend for the two kinds of foam was the same. When the oxidation degree was less than 15%, the compression modulus and strength weakened with the increase in weight loss rate, but the thermal conductivity decreased with the increase in weight loss rate, which was a favorable influence for the thermal protection system. The mechanical and thermal properties had a linear relationship with the weight loss rate, but the slope was different between 0% to 10% and 10% to 15%. The microscopic mechanism of these changes was also analyzed. As the cruising speed Mach number of hypersonic vehicles increases, the problem of aerodynamic heating becomes more prominent, especially along the sharp parts of the aircraft, where temperature can even exceed 1500 °C . LimitedThe basic properties of CF have been studied. Janszen  studied The challenge for CF applications in TPS is oxidation, and even if anti-oxidation measures are taken, this phenomenon can only be delayed rather than completely avoided. Oxidation not only jeopardizes the integrity of the structure, but also changes the properties of the material, resulting in structural properties that do not meet the requirements for use ,16,17,18The CF production process studied in this paper is as follows: pulverize the finely washed bituminous coal with a free expansion number of 5.5 to more than 100 mesh, put it into a mold, put it into a high temperature and high pressure reaction kettle with the mold, seal it and vacuumize it to below 0.001 MPa, close the vacuum, and pass high-purity nitrogen until the pressure reaches 1.5 MPa, heat up to 500 °C at a heating rate of 1 °C/min, keep the constant temperature for 300 min, naturally cool to room temperature, depressurize to atmospheric pressure, open the reactor, take out the material, and put it in a vacuum sintering furnace. Under vacuum conditions, the temperature was raised to 1650 °C at a heating rate of 1 °C/min, kept at a constant temperature for 300 min, and then cooled to room temperature at a cooling rate of 2 °C/min to obtain the CF required for the test ,24,25. I2 bubbling in MTS to the reaction chamber, employing H2 as the carrier and catalyst gas and argon as the dilute gas. The H2 flow rate was kept at 300 mL/min, while the Ar flow rate was kept at 200 mL/min. The deposition time and pressure were 300 min and 1.4 kPa, respectively. Then, the required ACCF was finished [A part of the above-mentioned CF was further anti-oxidative treated, and its process was as follows: CF is put into a chemical vapor deposition furnace, and the temperature is raised to 1075 °C after evacuation. Methyl-trichloro-silane (MTS) was carried by means of Hfinished ,28,29.In order to study the relationship between the mechanical and thermal properties of CF and the oxidative weight loss rate, this paper designed four groups of control tests, with four specimens in each group for a total of 16 specimens, numbered as A-1-1~A-1-4, A-2-1~A-2-4, A-3-1~A-3-4, and A-4-1~A-4-4, respectively. The preset oxidative weight loss rates of each specimen were 0%, 5%, 10% and 15%, respectively. In order to study the relationship between mechanical and thermal properties of ACCF and oxidative weight loss rate, limited by raw materials, this paper designed four groups of control tests, with two specimens in each group for a total of eight specimens, numbered as B-1-1, B-1-2, B-2-1, B-2-2, B-3-1, B-3-2, B-4-1, and B-4-2. The preset oxidative weight loss rates for each specimen were 0%, 5%, 10% and 15%, respectively. The size of the test parts was 30 mm × 30 mm × 15 mm ,32, as sSpecimens are calcined for 30 min in a tubular furnace at 400 °C under flowing nitrogen atmosphere to remove impurities. The specimens are taken out, cooled to room temperature, and weighed to obtain initial mass. The specimens are oxidized to a designed oxidative weight loss rate in a small tubular furnace as follows: (a) The specimen was put into the tubular furnace and heated to 600 °C at 10 °C/min for 5 min; (b) nitrogen at room temperature was fed into the furnace with a flow rate of 0.5 L/min for 3 min, to fully expel the oxidation exhaust gas and cool down the furnace temperature to 360–380 °C; (c) Fresh air at room temperature is fed into the furnace with a flow rate of 0.7 L/min for 5 min; the furnace temperature drops to 230–290 °C; (d) after repeating step A to C several times, take out the specimen and cool it to room temperature for weighing. Stop the test if the preset oxidation weight loss rate is met; otherwise, continue the oxidation.Step b and step c are the key to ensure the success of the test. In step b, specimens are cooled to below 400 °C, which is the starting temperature of carbon material oxidation, to avoid allowing the subsequent air into the outer surface at the beginning of oxidation. In step c, the tubular furnace should be kept heating while the air is passing through, which enables fresh air to get into the pores sufficiently. This will ensure the uniformity of the oxidation degree inside and outside the material.After the oxidation treatment of the specimens, the thermal property test is carried out first, because the thermal property test process will not damage the test part, and the test part can still be used for mechanical property measurement. In this paper, Hot Disk-TPS2500s (ISO 22007-2) transient heat flow method was used to test the thermal performance of specimens. The equipment requires that the specimens clamped with the probe have the same or similar thermal performance. The probe has a heating function and calculates the average thermal conductivity of the two specimens by measuring the heat flow on the back of the specimens. The thermal properties of each set of specimens were measured at room temperature (20 °C).CCF in thermal protection structure is subjected to a complex stress environment, and the basic mechanical properties of CCF include tensile, compression and shear properties. This paper only studied the compression properties of CF, because the compression properties of CCF were obtained by flat pressure test (ASTM C365/C365M), which is the simplest test method and consumes less material. Moreover, for porous materials such as CCF, their tensile, compressive and shear properties are all related to the mechanical properties of the carbon skeleton, and the relationship between all of the mechanical properties of the carbon skeleton and oxidative weight loss rate can be well revealed by studying the compressive properties. The flat pressure test was carried out on an Instron-8802 electro-hydraulic servo material test machine with loading speed of 1 mm/min.Since CCF is a brittle material, the unbroken part far from the fracture still has a relatively complete structure after mechanical property test, and it can be made into a SEM sample to observe the oxidation morphology of the pore wall. The model of SEM device is a TESCAN MIRA, at an accelerating voltage of 20 kV.Mechanical and thermal experiment results are listed in Due to the large amount of data, the stress–strain curve was drawn from the data of the two specimens with the largest and smallest oxidation weight loss rates in CCF and ACCF, as shown in In region A, different areas of the specimen participate in the bearing successively at the beginning of the test, causing the slope of the curve to increase, and the surface of the specimen is completely compacted with the platen in the end;In region B, CCF is uniformly stressed and linear, which is the main working section of the CCF. The slope and the max stress of region B are the compression modulus and compression linear strength of CCF, which are the most concerned performance data in the design of thermal protection structures, as listed in In region C, the slope decreases to minus, which means failure occurs and extends. At the end of region C, the foam is completely destroyed in the section perpendicular to the load direction, and the material should not be allowed to work at this stage when designing the structure;In region D, the CCF continues to failure, and fragments into several pieces in the longitudinal direction. This region is short, which cannot show the long platform area of plastic foam. This brittle feature is unique to CCF, which contains a large amount of disordered amorphous carbon ,29,30.The modulus and strength of A-4-4 are 10.08% and 9.9% of those of A-1-1, respectively, which means the mechanical properties are greatly attenuated. A-4-4 is the uniaxial compressive stress–strain curve of the original CCF after oxidation weight loss of 16.04%. Compared with the curve of A-1-1, it is smoother and lacks an obvious load drop. A-4-4 also did not fracture longitudinally, but was compacted and exhibited plastic foam characteristics. In previous studies , it was B-1-1 and B-4-2 are the stress–strain curves of ACCF, and it can be found that except for the slightly different modulus and strength (discussed later), they still follow the above rules of CCF.In region E, the compressive modulus decays linearly with the oxidation weight loss rate, and this process continues until the CCF loses 10% of its weight, at which time the compressive modulus is about 40% of the initial value;In region F, the rate of decay of the compressive modulus is significantly reduced;In region G, it shows that when the weight loss rate of CCF oxidation exceeds 15%, the compressive modulus decays faster than that in region E.The compressive modulus–oxidative weight loss rate curves of all specimens are shown in The compressive linear strength–oxidative weight loss rate curve is shown in The mechanical properties of ACCF have subtle differences compared to CCF. It can be reasonably inferred that its overall change trend is the same as that of CCF. Compared with CCF, the modulus of ACCF is about 3.8% higher, and the strength is about 6.9% higher, which may be because the SiC particles deposited on the carbon skeleton have a certain strengthening effect on the carbon skeleton.The thermal performance of the specimen measured by Hot Disk is the average value of the two specimens, so when studying the relationship between the thermal properties of CCF and ACCF and the oxidation weight loss rate, the abscissa takes the arithmetic mean of the two specimens, namely the average oxidation weight loss rate, thus obtaining the average thermal conductivity–average oxidation weight loss rate curve of CCF and ACCF ;In region I, the thermal conductivity also exhibits linear decay, but the decay slope decreases;In region J, the thermal conductivity suddenly increases. The mechanism is not yet clear, and further research is needed to eliminate interference.The SEM images of the pore wall surface are shown in The fact that the amorphous carbon is more consumed and the relative content of graphitized carbon increases with the deepening of the oxidation degree observed in the SEM in The reason for the decrease in thermal conductivity was that the amorphous carbon was oxidized in large quantities, the pore walls changed from dense to porous, as shown in The average thermal conductivity–average weight loss rate curve has the same trend as the compressive properties–weight loss rate curve and the compressive linear strength decay curve, and the turning points of the decay slope change are also close: the thermal conductivity curve is at 8% and 15% weight loss rate, while the compression is 10% and 15%. It is clear that this trend is strongly related to the changing relative content of amorphous carbon and graphitized carbon during the CCF oxidation process, but its specific mechanism of action, whether there are other factors, and why the mechanical and thermal properties change after 15% still remain to be studied. These studies may provide solutions for improving the residual mechanical properties of materials after oxidation.Antioxidation treatment has a small effect on the mechanical properties of CCF, but it will significantly increase the thermal conductivity of CCF, which has a negative impact on its thermal insulation performance. When designing thermal protection structures, attention must be paid to the measurement of thermal conductivity of ACCF and the SiC content. Antioxidation treatment did not alter the trend of change in the mechanical and thermal properties of CCF with the oxidative weight loss rate.When the weight loss rate was less than 15%, the thermal conductivity of CCF decreased with the increase in weight loss rate; when the weight loss rate was greater than 15%, the thermal conductivity of CCF increased with the increase in oxidative weight loss rate. The compressive modulus and compressive linear strength of CCF respectively decreased to 40% and 32% of their initial value when the weight loss rate was 10%, and to 31% and 20% of their initial value when the weight loss rate was 15%. However, the mechanical properties of CCF decreased rapidly when the weight loss rate was above 15%. Considering that the compressive modulus and strength of CCF used in thermal protection structures have relatively high design margins, CCF can be used with the maximum weight loss rate of 15%.The change in the mechanical properties of CCF with the weight loss rate is related to the relative content of amorphous carbon and graphitized carbon, and the mechanical behavior of CCF is similar to that of PCF when the degree of oxidation increases. This paper provides an important entry point for the study of the oxidation mechanism from a macroscopic point of view, and an important connection between the microscopic mechanism and macroscopic properties.


The knowledge of school nurses about the principles of self-control and the treatment of type 1 diabetes mellitus is insufficient. Due to the strong increase in the incidence of type 1 diabetes mellitus among children and adolescents, it is important to organize permanent, continuous, and mandatory training on the principles of self-control and the treatment of type 1 diabetes mellitus for school nurses. The equipment in Polish school nurses’ offices should be supplemented with a working glucometer and blood glucose test strips, and the set of obligatory medications in the school nurse’s office should be supplemented with glucagon for students with type 1 diabetes mellitus.School nurses should participate in the care of children with type 1 diabetes mellitus. The aim of this study was to assess the level of knowledge of school nurses about the basic principles of self-control and the treatment of type 1 diabetes mellitus and to attempt to determine the factors that influence this level of knowledge. A cross-sectional survey was conducted among school nurses from October 2018 to November 2019 in the Pomeranian Voivodeship. The study was conducted using a self-constructed questionnaire. The survey included questions about the sociodemographic characteristics of the respondents, and a test of the knowledge and skills regarding the principles of self-control and the treatment of type 1 diabetes mellitus (16 test questions). This study included 168 Polish school nurses (mean age ± SD = 55.1 ± 8.9 years). Most of the nurses had a secondary education (81%), worked in a municipal educational institution (78.6%), and provided care to more than one student with type 1 diabetes mellitus at school (70.2%). The average level of knowledge of school nurses was 12.5 ± 2.0 points (maximum 16). The nurses working in a village school and those who worked only in one school had lower levels of knowledge. Only 85.7% of nurses reported that they could independently perform a blood glucose measurement with a glucometer, and as many as 56.5% were unable to determine the level of ketone bodies in the urine with Keto-Diastix test strips. Only 62.5% of nurses had a glucometer and glucometer strips in their nursing office. A total of 19.6% of nurses did not have glucagon (1 mg GlucaGen HypoKit Type 1 diabetes mellitus, T1DM, is the most common chronic childhood disease .In the last decade, the greatest increase in the incidence of T1DM occurred in Polish children under the age of 15, especially those under the age of 5. The highest increases in the incidence are found in children aged 0–4 years .At diagnosis, children with T1DM often show symptoms of polyuria, polydipsia, and weight loss. Between 10% and 70% of these diagnosed children present in diabetic ketoacidosis ,4.The goal of treating diabetes in children and adolescents is to achieve and maintain proper, harmonious physical development, as well as the proper course of adolescence, appropriate to their age and gender, while ensuring a comfortable life for the child and his or her family ,5.Insulin therapy continues to be the primary treatment method. Insulin is given using an autoinjector pen or a personal insulin pump . The metStudies of the Diabetes Control and Complications Trial Research Group and the Epidemiology of Diabetes Interventions and Complications Research Group have shown that achieving and maintaining glucose levels leads to a reduction in the micro- and macro-vascular complications in T1DM ,8.To achieve optimal treatment results, children with diabetes should be cared for by a multidisciplinary team that includes diabetes educators, diabetes nurses, nutritionists, physiotherapists, social workers, psychologists, diabetologists, and other physicians . The cooperation of the diabetic therapeutic team with the school nurse and the family is aimed at providing a child with T1DM with the best care and the greatest possible safety in an educational institution.The aim of the study was to assess the level of knowledge of school nurses about the disease, the basic principles of treatment, and the occurrence of acute metabolic disorders and complications, as well as to determine the factors influencing their level of knowledge.This study was a cross-sectional survey conducted from 23 October 2018 to 30 November 2019 in the Pomeranian Voivodeship. The study participants were 168 professionally active school nurses. The data were collected during individual meetings with the school nurses or at a training conference organized by the Regional Council of nurses and midwives for school nurses. The inclusion criteria were active school nurses working in school, and the exclusion criteria were all nurses who do not work in schools.The study was conducted using a diagnostic survey method with a self-constructed questionnaire. When preparing the questionnaire, the factors that may affect the level of knowledge of school nurses were considered.The first page of the questionnaire contained information about the study and an invitation to participate. The survey questionnaire was divided into four parts.The first part of the survey contained questions about the respondent (the surveyed school nurse), i.e., sociodemographic data such as their age, education, whether they had completed postgraduate education , and caring for children and adolescents with diabetes), whether they had completed postgraduate education in the field of nursing in an educational setting , their workplace, and the number of facilities where the nurse works.The second part of the questionnaire consisted of questions about the characteristics of the school where the nurse works: the presence of a student with T1DM in school, the number of students with T1DM in school, the method of diabetes treatment used, the presence of an additional diseases in a student with T1DM, telephone contact with the parents of a sick child, and the equipment of the nursing office.The third part of the questionnaire included questions about the nurses’ skills and preparation for caring for a child with T1DM and whether they would like to participate in training for the control and treatment methods of type 1 diabetes, such as: can you independently measure the blood glucose level with a blood glucose meter? Can you measure the level of ketone bodies in the urine with test strips? What will you do if a student with T1DM becomes unconscious? How do you rate your preparation for caring for a student with T1DM? Would you like to repeat the training on the causes, symptoms, acute metabolic disorders, complications, and treatment methods for T1DM? What kind of training do you think would be the best for you?The fourth part of the questionnaire included a theoretical test on type 1 diabetes.The knowledge test consisted of 16 test questions concerning the essence of the disease (the definition of diabetes and the essence of type 1 diabetes), the basic principles of self-control and treatment  and the occurrence of acute metabolic disorders and complications .The test to check the level of knowledge was constructed based on the recommendations of the Polish Federation for Education in Diabetes and the Polish Diabetes Association. Each question contained one correct answer, for which the nurses received one point. A maximum of 16 points could be obtained.The data were collected using a paper version of the questionnaire. The questionnaires were distributed and collected personally by the researcher during individual meetings with school nurses or at a training conference organized by the Regional Council of nurses and midwives for school nurses. Participation in the study was voluntary.For each parameter, the mean (X), median (M), standard deviation , and lower and upper quartile  were calculated. The statistical significance between the means for different groups was calculated by a one-way analysis of variance (ANOVA), alternatively using the non-parametrical U Mann–Whitney test (for two groups) or Kruskal–Wallis test (for more than two groups), when the variances in the groups were not homogeneous (the homogeneity of variance was determined by the Levene’s test.The relation between the two parameters (the level of knowledge versus the age) was assessed using a correlation analysis and Spearman correlation coefficients were calculated.p value of less than 0.05 was required to reject the null hypothesis. Statistical analysis was performed using EPIINFO Ver. 7.2.3.1 and Statistica Ver. 13.3. software packages.A The study included 168 Polish school nurses from the Pomeranian Voivodeship  ,10.The average result of the test checking the level of knowledge of the school nurses was 12.5 ± 2.0 points (maximum 16).The results of the knowledge test are presented in Questions 4 and 5 were the most difficult. Question 4 concerned the basic principles of rational nutrition, and question 5 concerned the percentage composition of particular nutrients in the proper diet of a child with T1DM. The correct answer was given by only 25% and 58.3% of the respondents, respectively.The highest number of correct answers was obtained for questions 3 (94.6%), 6 (96.4%), 9 (96.4%), 13 (97.6%), and 14 (92.3%). Question 3 related to the definition of type 1 diabetes, question 6 related to the knowledge of the main sources of carbohydrates, question 9 assessed the general knowledge of exercise as an integral part of the proper management of T1DM, question 13 related to the type of exercise recommended, and question 14 checked the knowledge of acute metabolic disorders in T1DM that threaten the life of a student with T1DM.Most nurses  reported that they could independently perform blood glucose measurements with a glucose meter. However, 95/168 (56.5%) could not measure urine ketones with Keto-Diastix test strips. Most nurses  knew what to do if a student with type 1 diabetes became unconscious.®) or an ampoule with 20% glucose for an intravenous administration in their offices. A total of 16.7% (28/168) of nurses did not have a telephone number to contact the parents of a student with T1DM.A slight majority of the nurses  had a blood glucose meter and blood glucose meter strips in their offices. Approximately 19.6% (33/168) of nurses did not have glucagon  of nurses assessed their preparation for caring for a student with T1DM as low, 75.6% (127/168) as average, and 11.3% (19/168) as high.The majority of nurses  said they would like to repeat the training on the causes, symptoms, methods of preventing acute metabolic disorders, methods of self-control, and the treatment of type 1 diabetes. Only 25% of nurses (42/168) would like it to receive individual training.The authors analyzed the influence of various factors on the level of knowledge of school nurses.Nurses who were employed in only one school and those who worked in a rural school had a lower level of knowledge .School and preschool activity is a very important part of the life of every child and young adult with type 1 diabetes ,12,13. TClose cooperation between children, parents, school staff, and health care providers is needed to ensure that children and adolescents with T1DM are motivated to participate actively in all educational activities .The results of the largest clinical trial, the Diabetes Control and Complications Trial (DCCT), clearly demonstrated that the intensive therapy of T1DM to reduce blood glucose to the normal range is associated with a significant reduction in the risk of developing microvascular complications, retinopathy, and neuropathy .Based on these studies, the American Diabetes Association concluded that intensive care should be a method of treatment for all children with T1DM over the age of 13. The intensive treatment of type 1 diabetes improves the quality of life of children and adolescents with this disease.The above recommendations significantly changed the role of the school nurse in caring for children with T1DM in educational institutions.The school nurse has become one of the key elements determining the safety of a child with type 1 diabetes at school.School nurses should be responsible for the organization and implementation of medical care for children with T1DM in school or kindergarten. They are partners for children and adolescents with T1DM and their parents in the implementation of the treatment and self-monitoring process ,16.In schools, the proper organization of diabetes care requires the training of all school staff on type 1 diabetes and the principles of its treatment, including the acceptance of the principles of self-control and joint responsibility for the organization of diabetes care ,17,18.The aim of our study was to assess the level of knowledge of school nurses on the essence of the disease, the basic principles of treatment, and the occurrence of acute metabolic disorders and complications. It was also an attempt to determine the factors influencing their level of knowledge. The research was carried out with 168 school nurses. The average age of the respondents was 55.1 ± 8.9 years. Most nurses had secondary education (81%), worked in a municipal educational institution (78.6%), and cared for more than one student with T1DM (70.2%). As many as 13% of nurses did not know what method a student with T1DM was treated with, and approximately 17% did not have a phone number to contact the parents of a child with T1DM.Only 85.7% of nurses were able to perform a blood glucose test with a glucose meter, but 56.5% were unable to determine the level of ketone bodies in the urine with the Keto-Diastix test strips.®) or a 20% glucose ampoule for an intravenous administration in their offices.More than half of the nurses (62.5%) had a blood glucose meter and blood glucose meter strips in their offices. A total of 19.6% of nurses did not have glucagon  and the percentage of particular nutrients in a meal for a child with T1DM (58.3% correct answers).In the literature, seven studies were found on the assessment of the level of knowledge, competence, and self-efficacy in the field of diabetes therapy in school nurses.Surveys concerning the assessment of the level of knowledge of school nurses on the self-control and treatment of T1DM were conducted in Poland, Kuwait and the United States.p = 0.009). School nurses perceived their knowledge of diabetes to be better than their actual knowledge. Scores on the Diabetes Awareness Questionnaire were higher in nurses with a higher education (p = 0.024), those who had relatives or friends with diabetes (p = 0.032), and those who had previously received diabetes training (p = 0.05) [The Polish study by Kobos et al. presents the actual and perceived level of knowledge about diabetes among 230 Warsaw school nurses. It concerns school nurses working in schools of one of the largest cities in Poland . The percentage of correct responses in the Diabetes Knowledge Questionnaire was 46.7%, with the lowest scores related to the knowledge of insulin pumps (36.5%), nutritional principles (37.4%), and insulin therapy and glucagon administration (37.9%). The actual and perceived diabetes knowledge were moderately positively correlated  ,20.In our study, not all nurses were able to independently perform blood glucose measurements with a glucometer and determine the level of ketone bodies in the urine with Keto-Diastix test strips, and not all knew what to do if a student with T1DM lost consciousness. Only 11.3% of nurses rated their preparation for caring for a student with T1DM as high. It was shown that nurses who were employed in only one school and those who worked in a rural school had a lower level of knowledge.Research conducted in Kuwait and the United States shows the impact of educational training on the level of knowledge and skills in the principles of self-control and treatment of T1DM among nurses and school workers.Tahaa et al. assessed the impact of e-learning training on the level of knowledge of school workers in Kuwait. A total of 124 employees  from 31 public schools participated in the training. Before and after the diabetes training, the participants were asked to complete a questionnaire verifying their level of knowledge about diabetes. The authors of the study stated that the online training significantly increased the level of knowledge of the school staff about diabetes. The level of diabetes awareness remained the same 12 months after completing the online training. The school staff showed significantly greater self-confidence while caring for students with diabetes .p = 0.01), and the sense of self-efficacy improved by 2.7% (p = 0.007). Researchers found that developing the competencies of school medical personnel through intensive training and the practical use of specialist knowledge can help organize and provide the best diabetes care in an educational institution [In Colorado, the United States, Berget et al. assessed the diabetes care provided by schools and the necessary knowledge and skills of school medical personnel and explained the role of school medical personnel in diabetes care. The level of knowledge, competence, and self-efficacy in the field of diabetes therapy was assessed before and after the course. The study included 30 school nurses. The level of knowledge, competence, and self-efficacy in the treatment of diabetes improved significantly after the implementation of the diabetic course. The level of diabetes knowledge increased by 3.5% (titution .SM) implemented in Chandler, Arizona, Columbus, Ohio, El Paso, Texas, Kingston, New York, Naperville, Illinois, Queensbury, San Diego, and California. H.A.N.D.S.SM is a continuing education program aimed at improving the level of experience and competence in performing the services associated with diabetes care. The level of experience and competence in the field of diabetes care was assessed among 105 school nurses before and after the training. The survey was conducted via email. The participants’ levels of experience and competence for each of the four categories of diabetes care improved significantly, and a greater number of nurses reported being able to perform the services independently and having the ability to teach others [Other American researchers tried to evaluate the effectiveness of the educational program Helping Administer to the Needs of the Student with Diabetes in Schools . A total of 1977 school nurses in Missouri were invited to participate in the training, and the researchers assessed their initial and final levels of knowledge. A total of 678 school nurses completed the entrance test, and 449 completed the final test. The authors of the study found that the level of knowledge of school nurses increased significantly compared to the initial level. The training provided personalized, flexible, computerized information on diabetes and care plans. In their conclusions, the authors emphasized that e-learning is a convenient and effective way of providing professional development opportunities and raising the knowledge of school nurses .In Normandy, an online continuing education program for school nurses on self-management and diabetes management for students was implemented and evaluated using current policies. Nineteen school nurses who were unable to attend on-site diabetes training across the state were recruited for the study. Most of the school nurses stated that the goals had been achieved. A total of 91% of respondents said that the education would improve their skills of coping with students who had diabetes. The authors of the study emphasized that due to the increasing prevalence of diabetes in children, it is important that school nurses have constant access to lifelong learning, which includes the current codes of practice in children with diabetes .In Indiana, the United States, a survey was conducted among school workers to assess the effectiveness of a basic and extended education program on the principles of therapy and the self-management of T1DM. This project examined the initial and final knowledge of school workers about the principles of therapy and the self-management of T1DM and their confidence in caring for students with diabetes. Forty-four employees participated in the basic training, and 37 participated in the extended training, including 22 (59.5%) aides/assistants, 5 (13.5%) clerks, 3 (8.1%) nurses, and 7 (18.9%) other staff. The authors of the study showed that the general knowledge about the self-control and treatment of diabetes and the self-confidence in caring for a student with diabetes increased significantly after both basic and extended training compared to the initial level .It is very important to underline that on an ongoing basis, school nurses identify the health problems of students with T1DM, formulate nursing diagnoses, and conduct nursing assessments; they develop, implement, coordinate care plans for individuals, groups, parents, and teachers, and assess the necessary supplies for medical care services ,28.The main limitations of this study were as follows: the questionnaire was not tested for its validity and reliability, and the study was performed only in one region of Poland.The knowledge of school nurses about the principles of self-control and the treatment of type 1 diabetes is insufficient. Due to the intense increase in the incidence of type 1 diabetes in children and adolescents, it is important to organize permanent, continuous, mandatory training on the principles of self-control and the treatment of type 1 diabetes for school nurses. Politicians, directors of medical units, and school principals should ensure a safe school environment for students with type 1 diabetes and implement appropriate interventions to support them, including methods for resolving the health, psychological, and social problems. It is necessary to provide all students with type 1 diabetes with access to medical services provided by nurses. The equipment of the Polish school nurse’s office should be supplemented with a working glucometer and blood glucose test strips, and in the case of the presence of a child with type 1 diabetes among students at school, a set of obligatory medications from the school nurse’s office should be supplemented with glucagon.


The paper presents the results of the research on the impact of process parameters of high-pressure, cold-chamber die casting of an industrial casting made of aluminium alloy on the casting properties assessed macroscopically by measuring the casting average density and microscopically through the characteristics of the casting microstructure. The analysis covers the influence of three selected velocity settings of the pressing plunger, which determine the filling time, and three values of the compression pressure setting characteristic of the third phase of the casting process. The cooling and solidification simulations of the casting were performed using the ProCAST software. During the simulation tests, the impact of the filling rate of the alloy into the die cavity on the cooling rate and the alloy solidification path at selected points were determined. The conducted research allowed linking the process parameters with the parameters of the casting structure with different wall thicknesses. Metallographic examinations of the castings were carried out using a light microscopy, SEM, and EDS analysis. The fraction of the phases α(Al), the size of dendritic cells, and the size of silicon particles, in the cross-sections of the castings with wall thickness of 3, 6, and 11 mm, respectively, were determined. High-pressure die casting (HPDC) is treated by the recipient as a homogeneous, basically autonomous object, the assessment of which takes into account the positive fulfilment of certain features defined in the context of intended use and conditions of the use of castings ,2,3,4. AIn industrial practice, the basic parameters of the casting process under high pressure (including filling time and compression pressure) are the input data for the correct design of the gating system, and thus the high-pressure die . The samSuggested ranges of individual HPDC process parameters are available in the literature ,18,19,20A long-time observation of industrial practice allows us to assume that for a specific type of castings, there must exist such a time range for filling the die cavity (and parameters related to it) that will enable obtaining the best effect of the specific pressure applied, and vice versa, there should be a specific pressure that will give a satisfactory effect, provided that the die is filled in the right time ,14. On tThe castings obtained in the HPDC technology are usually thin-walled ones which are characterized by a high cooling rate and a short solidification time. In the case of HPDC technology and thin-walled castings, the key issue in attaining homogeneous structures and properties free from castings defects is the sensitivity of Al-Si alloys to the cooling rate, especially when the range of the high cooling rates is taken into consideration. The cooling rate (K/s) determines the fragmentation of the dendrites of the α (Al) phase, the type of eutectic (lamellar or fibrous), and the morphology of other phases, including iron ones (sludge). The cooling rate is usually determined when the alloy reaches the equilibrium solidification temperature of the alloy (liquidus temperature). The cooling rate reflects the heat transfer conditions of solidification ,15 and cAs part of the presented work, a casting that was analysed was a component of one of the key systems of a modern internal combustion engine. The objective of the study is to find out the influence of the parameters of the high-pressure die casting process, mainly the pressure as well as the rate and time of filling the die, on the parameters of the casting microstructure in thin and thicker sections located closer to or further from the gatings. The use of numerical modelling allowed simulation of the course of filling the die cavity and of the solidification of alloys in areas with different wall thicknesses. The determined cooling rates and solidification times were linked to the parameters of the HPDC process. These results will extend the knowledge regarding production stability, structure formation, and minimizing generation of casting scrap.The base-line material was a secondary AlSi9Cu3(Fe), Alumetal Poland SP. Z.O.O, Kęty, Poland, cast alloy EN AC-46000. The alloy was melted in an 800 kg industrial electric resistance furnace with preheating to a temperature of 1023 ± 5 K (750 ± 5 °C). Alloy composition was determined using a GNR Solaris NF  optical emission spectrometer on the samples taken directly from the casting . All the® software  to determine the local cooling rate of the alloy during the process. For each casting, measurements of piston path, piston speed, and pressure in the pressing cylinder over time were recorded. Based on these real curves, piston motion parameters were created for ProCAST simulations.A series of numerical simulations were carried out using ProCAST, ESI GroupThe temperature dependencies of the thermophysical parameters of the alloy used, necessary for the simulations, were obtained by thermodynamic calculations. For this aim the CompuTherm LLC Thermodynamic Databases of ProCAST was used . These rThe test casting was a water pump housing produced for one of the world’s leading automotive brands. The castings were made on a Frech DAK720-62 cold chamber die casting machine. The tests were carried out on a 4-cavity die, from which, in order to minimize the impact of non-simultaneous filling of individual cavities, only castings from one precisely defined cavity were selected for further analysis.Tests included making castings for three selected settings of plunger velocity and also for the three selected values of III-phase pressure settings. Three samples representing wall thicknesses of the casting of 3, 6, and 11 mm, respectively, were cut out. From the samples, specimens for metallographic tests were made. A dose of 1.55 kg was used to produce one bundle of castings shown in Test 1: Changing the setting of the compression pressure (process phase III) at a constant velocity of the pressing plunger in phase II of the process .Test 2: Changing the velocity setting of the pressing plunger in phase II of the process, at a constant compression pressure (phase III of the process).As part of the more extensive research, the following values of the variables marked in A summary of the parameters of the high-pressure die casting process used in the tests is presented in Area 1 a, markedArea 2 a, markedArea 3 b, markedPump body casting selected for the analysis  remained unchanged and were based on settings that gave a satisfactory quality effect in the production of a casting.®. Calculations were performed using the finite element method (FEM).Simulations were carried out using Visual-Environment 16.0  integrated software with ProCAST 2020.0 solver, ESI GroupThe FEM mesh step size for the casting was taken to be equal to 1 mm b. In the2·K) was assumed for the liquid state, and 1 kW/(m2·K) for the solid state. For the solidification temperature range, the HTC value was approximated by a linear relationship based on the above limits.A variable value of heat transfer coefficient (HTC) in the contact between the alloy and the forming inserts was assumed, depending on the temperature of the alloy in contact with the mould. HTC = 10 kW/ was assumed. Temperature distribution on the walls of die cavity taken as the initial condition in the cavity filling simulation is shown in α phase grains, the dendritic cell size dα, and the size of silicon particles in eutectics, Lmax. Microscopic examinations were carried out on polished and un-etched samples.A metallographic characterization was made using a Leica MEF 4M  light microscope and a QWin v3.5  image analysis software at various magnifications to examine microstructure of Al-Si-Cu castings. Light microscope examinations included measurements of the fraction of α(Al), fAll investigated castings were subjected to an average density test. The density of individual samples taken from the casting was measured by hydrostatic weighing (based on Archimedes’ law). Distilled water was used as the working fluid. The RADWAG WAS 160/X laboratory instrument balance with a factory density measurement kit was used.The results of the alloy density tests are presented in Alloy in the area 1 a of the Simulations of the die cavity filling, alloy cooling, and solidification were performed to correlate cooling conditions with microstructure test results. The inputs for this simulation were the chemical composition of the alloy, the thermophysical parameters of the materials involved, and the alloy-die and die-environment heat transfer coefficient. In addition to the geometry of the die cavity shown in The simulation results of cooling curves and solid fraction changes during solidification obtained by ProCAST software  are shown in V2 on the cooling rate of the casting close to the equilibrium alloy solidification temperature of α(Al) phase and on the alloy solidification time.V2 parameter has the greatest impact on the cooling rate before the solidification process begins. For a casting with wall thickness of 11 mm, the changes in the cooling rate are insignificant. In all analysed cases, entering the scope of thin-walled castings is characterized by an intensive increase in the cooling rate regardless of the value of the V2 parameter. The highest increase in the cooling rate was observed for the thin-walled casting (g = 3 mm) at the highest applied velocity V2 of 3.5 m/s. The alloy solidification time determined on the basis of the ProCAST simulation in the analysed positions varies from about 1.4 to 6.1 s for castings with a wall thickness of 3 and 11 mm, respectively.The data presented in CR on the local wall thickness  and plunger velocity during the second phase of pressing —Equation (1) with the correlation coefficient R2 = 0.99. The dependence of the solidification time tK on the wall thickness of the casting and plunger velocity  is described by the Equation (2) with the correlation coefficient R2 = 0.99.On the basis of the analysis for the tested casting, it is possible to formulate the dependence of the cooling rate dα parameter by an average of 55% in the entire range of the applied pressure P3  and is more visible in the case of thicker casting walls (approx. 7%).e P3 see . IncreasV2 velocity settings on the change of the dα parameter value in the walls of different thicknesses was assessed. The obtained dependencies are presented in a graphical form in Similarly, the impact of the dα. At V2 = 3.5 m/s, the influence of wall thickness on this microstructure parameter is not so strong. The dα value in an 11 mm wall is only 1.68 times greater than in a 3 mm wall.The analysis of the results  demonstrP3 pressure settings on the change in the Lmax parameter value. It can be seen that increasing wall thickness from 3 to 11 mm has resulted in an average about two-fold increase in the Lmax parameter over the entire range of the applied pressure P3. Moreover, increasing the P3 pressure in the range of 160–290 bar reduces the Lmax parameter by an average of 22%.V2 velocity settings on the change in the maximum silicon particle size (Lmax). They show that increasing wall thickness from 3 to 11 mm at the velocity setting of 0.5 m/s has resulted in an almost 2.5-fold increase in the maximum size of silicon particles in the casting wall g = 3 mm, increasing to over 3 times the value for g = 11 mm and velocity V2 = 3.5 m/s. A decreasing effect of increasing the velocity on Lmax, reaching at V2 = 3.5 m/s the value of Lmax = 22 µm can be observed. Additionally, it can be concluded that increasing the velocity of V2 at a given pressure results in a more pronounced decrease in Lmax in the wall g = 3 mm (by about 40%), by a half lower in the case of g = 6 mm (by about 25%), and the smallest decrease in the wall g = 11 mm (about 20%).Increasing wall thickness of the castings significantly affects the cooling rate a and the153Si2 and the phases typical of the 46000 alloy, i.e., Mg2Si and Al8Mg3FeSi6 (Q phase). The silicon eutectic contains silicon plates, the size of which increases by increasing the wall thickness of the castings. As can be seen in The castings’ microstructure  consistsChanging wall thickness and process parameters significantly affects the size of dendritic cells. The size of dendritic cells grows together with the increase of the wall thickness of the castings. From The Sludge Factor (SF) parameter of Al-Si alloys, which is expressed as , was detxy sludge particles can significantly affect the crack nucleation stage, which has a clear negative effect on the reduction of the fatigue strength of the alloys, as reported in [For the analysed alloy, SF = 1.799, which corresponds to the proportion of Fe-containing particles at the level of 1% vol. The research  demonstrorted in .15Si2M4, Al9Fe2Si2, Al18Fe2Mg7Si10, Al8Mg3FeSi6, and Al2Cu_C16.Changes of the phase composition of the investigated alloy were calculated using “Thermo-Calc 2019a” database TCAL7. Results of the Thermo-Calc calculation for the chemical composition of the investigated alloy presented in 7Al5Si14 intermetallic phase should occur. When lowering the alloy temperature to the temperature of the initiation of α-Al solidification, particles of other intermetallic phases may solidify from the liquid, i.e., Al13M4 and Al153Si2, called sludge particles in the literature. The name is related to the fact that the presence and increase in the amount of these precipitates increases the viscosity of the suspension. The solidification of α-Al dendrites begins after exceeding 590.9 °C and the solidification of the α-Al + Si eutectic after exceeding 566.8 °C. In equilibrium conditions, solidification is completed at a temperature of approximately 478°C. In the course of further cooling in the solid state, particles of other intermetallic phases  may be precipitate. These particles are called secondary precipitations.According to the thermodynamic database, at the temperature of the analysed alloy in the reheating furnace (750 °C) in the bath, apart from the liquid phase, the precipitation of the TiAs it follows from P3. For the lowest value of plunger velocity, the highest share of primary iron-reach particles was observed. Together with the increase of plunger velocity, their fraction and size decrease. The cooling rate thus affects the sludge particles which is in line with the research carried out by Ferraro, Ceschini [The analysis of the microstructure showed that reducing wall thickness, i.e., increasing the cooling rate in the analysed range, causes an insignificant reduction in the size of the primary iron-reach particles. Their largest fraction occurred in castings obtained with the lowest compression pressure (castings from the A series). Increasing the compression pressure significantly affects the fragmentation of the primary iron-reach particles. This is already noticeable with a compression pressure of 210 bar (samples from the E series). The role of plunger velocity in the second phase of the cycle is analogous to the effect of compression pressure Ceschini ,27.In addition to the primary particles (sludge particles), there are secondary, fine polyhedral α-Fe particles in the microstructures, as shown in The presented studies not only confirm the general literature data, obtained mainly as a result of simulation calculations, on the effect of wall thickness of a high-pressure die casting on the solidification rate, but also expand them. A significant differentiation of the microstructure and phase composition of the EN-AC 46000 aluminium-based alloy was demonstrated, occurring in different regions of the casting obtained in the same process conditions.V2 cycle, amounting to 3.5 m/s. The solidification time of the alloy determined on the basis of the ProCAST simulation at the analysed points varied from about 1.4 s for a wall thickness of 3 mm to 6.1 s for a wall thickness of 11 mm.The analysed high-pressure casting with various wall thicknesses (3–11 mm) was characterized by a high variability of the cooling rate and solidification time. The highest cooling rate was observed in the casting with the least analysed wall thickness of g = 3 mm at the highest plunger velocity in the second phase of the HPDC The mathematical dependencies linking wall thickness of the casting, plunger velocity, and cooling rate, as well as wall thickness, compression pressure, and solidification time, were presented.Different microstructures of EN 46000 alloy were obtained for castings with wall thicknesses in the range of 3 up to 11 mm. The microstructures were characterized in detail, quantifying the average diameter of dendritic cells, maximum size of silicon particles, as well as size and distribution of iron-reach particles. These features became finer as the solidification rate increases. It was shown that increasing compression pressure insignificantly reduced the size of dendritic cells. Reducing the filling time of the die cavity by increasing plunger velocity had a much greater effect on reducing the dimensions of dendritic cells. This impact was greater for thicker parts of the castings.P3. For the lowest value of plunger velocity, the highest share of primary iron-reach particles was observed.The analysis of the microstructure showed that reducing wall thickness, i.e., increasing cooling rate, caused a slight reduction in the size of the primary iron-reach particles. Their largest share occurred in castings obtained with the lowest compression pressure (castings from the A series). Increasing compression pressure significantly affected the fragmentation of the primary iron-reach particles. It was already noticeable with a compression pressure of 210 bar (samples from the E series). The role of the plunger velocity in the second phase of the cycle was analogous to the effect of the compression pressure On the basis of the conducted research, the following conclusions can be drawn.


The growing interest of the scientific community in trail running has highlighted the acute effects of practice at the time of these races on isolated aspects of physiological and structural systems; biological, physiological, cognitive, and muscular functions; and the psychological state of athletes. However, no integrative study has been conducted under these conditions with so many participants and monitoring of pre-, per-, and postrace variables for up to 10 days over a distance close to 100 miles.The aim of this study was to evaluate the kinetics of the performance parameters during a 156 km trail run and 6000 m of elevation gain in pre-, per-, and postrace conditions. The general hypothesis is based on significant alterations in the psychological, physiological, mechanical, biological, and cognitive parameters.The Trail Scientifique de Clécy took place on November 11, 2021. This prospective experimental study provides a comprehensive exploration of the constraints and adaptations of psychophysiological and sociological variables assessed in real race conditions during a trail running of 156 km on hilly ground and 6000 m of elevation gain (D+). The study protocol allowed for repeatability of study measurements under the same experimental conditions during the race, with the race being divided into 6 identical loops of 26 km and 1000 m D+. Measurements were conducted the day before and the morning of the race, at the end of each lap, after a pit stop, and up to 10 days after the race. A total of 55 participants were included, 43 (78%) men and 12 (22%) women, who were experienced in ultra–trail-running events and with no contraindications to the practice of this sport.The launch of the study was authorized on October 26, 2021, under the trial number 21-0166 after a favorable opinion from the Comité de Protection des Personnes Ouest III (21.09.61/SIRIPH 2G 21.01586.000009). Of the 55 runners enrolled, 41 (75%) completed the race and 14 (25%) dropped out for various reasons, including gastric problems, hypothermia, fatigue, and musculoskeletal injuries. All the measurements for each team were completed in full. The race times  ranged from 17.8206 hours for the first runner to 35.9225 hours for the last runner. The average time to complete all measurements for each lap was 64 (SD 3) minutes.The Trail Scientifique de Clécy, by its protocol, allowed for a multidisciplinary approach to the discipline. This approach will allow for the explanation of the studied parameters in relation to each other and observation of the systems of dependence and independence. The initial results are expected in June 2022.RR1-10.2196/38027 Trail running is a sport discipline defined by the International Trail Running Association as a pedestrian competition taking place in a natural environment in a semi–self-sufficient or self-sufficient manner and with respect for sports ethics, fairness, solidarity, and the environment .runners identified in France in 2017 ) with diameters <1 µm (PM1), <2.5 µm (PM2.5), and <10 µm (PM10). Environmental parameters such as temperature, humidity, and atmospheric pressure were also recorded.Crosscall Core T4 tablets (France) with Quicktape Survey software (Canada) were used to merge the questionnaires of each scientific team.To reduce the impact of one measure on another for the prerace measurements, the order of passage of the tasks was imposed. Therefore, no randomization was performed.P˂.05. Depending on the scientific team, we will use MedCalc Statistical Software (version 13.2.0) and JASP (version 0.16.1.0) or RStudio (version 1.2) to perform the statistical analyses.Data related to the primary and secondary objectives will be evaluated at the end of the study. For each studied parameter, the normality of the distribution will be examined using the Shapiro-Wilk test. Continuous quantitative variables will be expressed as mean (SD), discontinuous variables as median and IQR, and qualitative variables as percentages. The comparison of the values of the primary end point between the baseline and the end of the study will be performed using statistical tests for the paired series. In addition, to take into account repeated measures over time, we will analyze the primary end point as a function of time using appropriate mixed models for repeated data. Using the same statistical tests as for the primary end point, we will analyze the secondary end points. The threshold for statistical significance will be defined as The launch of the study was authorized on October 26, 2021, under trial number 21-0166 after a favorable opinion from the Comité de Protection des Personnes Ouest III (21.09.61/SIRIPH 2G 21.01586.000009).Of the 60 runners selected for the scientific trail, 56 (93%) showed up, and 55 (92%) were selected for the study, including 43 (72%) men  and 12 (20%) women .A woman was excluded from the study because of her participation in a 160 km ultramarathon 1 week before the protocol.There were 14 participants who abandoned the study for the following reasons: perceived hypothermia , generalized exhaustion , gastric problems , and musculoskeletal pain .We performed intermediate times over the entire race. In a classic trail-running race, running and stopping times are part of the final timing. Here, this value is represented by the total time.For finishers, the average time for science over the whole race was 320 (SD 56) minutes . As an indication, the time spent at the base of life for refreshments, a nap, foot care, and physiotherapy represented 8.6% (SD3.7%) of the protocol time.For did not finish, the science time corresponded to 18.2% (SD 3.9%) of the protocol time, and 8.6% and SD 3.5%) of the protocol time was devoted to stops at the base of life.The average time per loop is presented in No runner had to interrupt the race because of an undesirable effect of the protocol.We noted a few lipothymia cases, which were not serious, during certain scientific tests, particularly those requiring prolonged standing.We did not note any muscle damage related to the tests.The venipunctures generated ecchymosis because of the difficulty of puncturing but also extravasation secondary to the rapid resumption of the race (strong and lasting compression not being possible).Anecdotally, 8 punctures, 6 of which were during the race, were a major constraint.The Trail Scientifique de Clécy allowed, for the first time, an integrative and multidisciplinary approach to better understand the performance of ultramarathons. The hypotheses based on the observations of the studies conducted in trail running go in the direction of degradation of many functions in the first one-third of the race before reaching a plateau in the last one-third of the race, suggesting that the differences in certain parameters of tiredness are no longer significant between the arrival of 100 miles or 200 miles in a mountain ,48,92-94Thus, our initial hypothesis was that there is a significant degradation of all the studied functions under the effect of race-induced fatigue from the first one-third of the race before reaching a plateau on the third one-third. We assume that a difference or difference in the kinetics of the studied functions can lead to failure and abandonment.Owing to its duration, a mountain ultramarathon induces night and day phases, which can induce a circadian effect on the fluctuation of physiological and cognitive functions. Our team is interested in verifying whether there is a circadian effect on the kinetics of the functions studied during the Trail Scientifique de Clécy, according to the running time and the time of day.Our study population is representative of the real population of a classic ultratrail race. Our average age  is in line with the recent observations, who reported that the average age of the different races of the Ultra Trail du Mont Blanc (Courmayeur Champex Chamonix and Orcières Champex Chamonix) from 2014 to 2018 for the 40 to 49 age group is the most represented . ConcernThe downtime imposed to meet the requirements of the scientific protocol did not exceed 20% of the total time. These data allow us to justify that our scientific race model is closer to reality because of the reduced duration of the stopping time for scientific tasks compared with the duration of the race and voluntary stops.The originality of this project is that it has allowed an integrative approach to the different parameters determining performance in ultraendurance. Our protocol allowed us to standardize the measurement points with a fixed and identical loop for each lap to collect fixed or continuous measurement points over the entire course, which is not the case in rare studies conducted in racing -26. The The first results for each scientific task are expected in June 2022.