Test Material Research Articles

The influence of age on the biological response to biodegradable zinc arterial implants

Medical devices to treat arterial diseases of older humans are routinely designed and developed using young animals. This is the case despite the significant declines of tissue regeneration, cell proliferation, and inflammation in aged humans that are not reflected in young animals. The widespread use of age-mismatched animals is particularly a concern for the testing of interactive materials, such as biodegradable metals whose dynamic interfaces continuously impact local cell and tissue regenerative processes. In order to determine the importance and impact of age differences in biodegradable stent material biocompatibility, we implanted both inert (platinum) and biodegradable (zinc) metal wires into the arteries of 1 year old and 3-month-old rats for a period of 6 months and compared the biological responses. It was found that the older animals developed a significantly larger neointimal encapsulating tissue for zinc implants vs. a smaller tissue response for the platinum implants relative to the younger rats. The neointimas of older rats contained dramatically fewer macrophages for both implant metals. The presence of neointimal smooth muscle cells was also decreased in the older rats. Endothelial cell regeneration in the old arteries was not impacted by the different metal implants. These findings demonstrate that neointimal responses to metal implants in arterial tissue are strongly impacted by age-related changes. The findings also suggest that the reliance on young animal models to evaluate metal implants intended for the arteries of considerably older individuals may substantially over predict the biocompatibility.

Hygrothermal Degradation of Epoxy Electrical Insulating Material—Testing and Mathematical Modeling

The degradation of electrical insulating materials has been a subject of interest for decades as they are commonly applied in many fields of electrical engineering. Suitably modeling such a process is important since the known and well-described degradation process reveals the effect of ambient conditions, and this allows us to possibly estimate a material’s remaining useful life. However, not many studies are dealing with the effect of the hygrothermal degradation of impregnating mono-component epoxy resins in the context of electrical engineering. Therefore, this study deals with this issue and discusses both the dielectric response (based on the measurement of relative permittivity, dissipation factor, and dielectric strength) and the mechanical response (based on measurements of tensile strength and Shore D hardness) to a hygrothermal degradation experiment. In addition, the results of thermal analyses are presented for the evaluation of the pristine specimen manufacturing process and possible post-curing processes. Furthermore, this study presents several methodologies for modeling the degradation process, including a novel methodology in this area based on Bayesian experimental design. As an outcome, mechanical parameters are proven to be specific in terms of the actual condition of the material and the Bayesian enhanced degradation model seems to be superior to the conventional evaluation methods in this particular study.

Preservatives for postmortem brain tissue in biomechanical testing: A pilot study.

Postmortem human subject (PMHS) studies are essential to brain injury research in motor vehicle safety. However, postmortem deterioration reduces the similarity between postmortem test results and invivo response in material testing of brain tissue and in biomechanical testing of the whole head. This pilot study explores the effect of potential preservatives on brain tissue breakdown to identify promising preservatives that warrant further investigation. To identify preservatives with potential to slow postmortem degradation, samples from an initial PMHS were refrigerated at 10°C to qualitatively compare tissue breakdown from 58 to 152 h postmortem after storage in candidate solutions. On brain tissue samples from a second PMHS, compressive stiffness was measured on six samples immediately after harvest for comparison to the stiffness of 23 samples that were stored at 10°C in candidate solutions for 24 h after harvest. The candidate solutions were artificial cerebrospinal fluid (ACSF) without preservatives; ACSF with a combination of antibiotics and antifungal agents; ACSF with added sodium bicarbonate; and ACSF with both the antibiotic/antifungal combination and sodium bicarbonate. Results were analyzed using multiple linear regression of specimen stiffness on harvest lobe and storage solution to investigate potential differences in tissue stiffness. Qualitative evaluation suggested that samples stored in a solution that contained both the antibiotic/antifungal combination and sodium bicarbonate exhibited less evidence of tissue breakdown than the samples stored without preservatives or with only one of those preservatives. In compression testing, samples tested immediately after harvest were significantly stiffer than samples tested after 24 h of storage at 10°C in ACSF (difference: -0.27 N/mm, 95% confidence interval (CI): -0.50, -0.05) or ACSF with antibiotics/antifungal agents (difference: -0.32 N/mm, 95% CI: -0.59, -0.04), controlling for harvest lobe. In contrast, the stiffness of samples tested after storage in either solution containing sodium bicarbonate was not significantly different from the stiffness of samples tested at harvest. There was no significant overall difference in the mean tissue stiffness between samples from the frontal and parietal lobes, controlling for storage solution. Given the importance of PMHS studies to brain injury research, any strategy that shows promise for helping to maintain invivo brain material properties has the potential to improve understanding of brain injury mechanisms and tolerance to head injury and warrants further investigation. These pilot study results suggest that sodium bicarbonate has the potential to reduce the deterioration of brain tissue in biomechanical testing. The results motivate further evaluation of sodium bicarbonate as a preservative for biomechanical testing using additional test subjects, more comprehensive material testing, and evaluation under a broader set of test conditions including in whole-head testing. The effect of antibiotics and antifungal agents on brain tissue stiffness was minimal but may have been limited by the cold storage conditions in this study. Further exploration of the potential for microbial agents to preserve tissue postmortem would benefit from evaluation of the effects of storage temperature.

Experimental system and method of aerobic thermal environment simulation based on laser heating

Considering the superior luminous intensity characteristics of lasers, a thermal simulation platform employing laser-induced heating in an aerobic environment was developed. Achieving a uniformly distributed flat-topped square laser beam output was facilitated through optical fibre bundling techniques, while precise control over laser power output was attained through current modulation. Utilising the aforementioned system, thermal shock simulation experiments were conducted in an aerobic environment, subjecting two types of high-temperature-resistant composites, namely C/C and C/SiC, to temperatures up to 1800 °C. These composites were lightweight, heat-resistant materials designed for hypersonic vehicle applications. The results show that the system and method can be used to simulate high temperatures, rapid temperature increases, and thermal shocks on C/C composite materials, with minimal variation in the coupling coefficient under aerobic conditions. The system and method can also provide key technology support for thermal-force-oxygen coupling testing of high temperature resistant materials.

Fabrication and Testing of Hybrid Polymer Composite Material by Using Carbon, Glass, Kevlar Fibers

Composites which made up of fiber reinforcements are universally endorsed option for the automobiles with a lightweight. Due to the unique properties of fiber-reinforced composites, it became a perfect alternative for traditionally used materials. Most of the automobile industries prefer polymer matrix fiber-reinforced composites for the reason that its light weight helps in carbon emission reduction and Additive manufacturing (AM) produces a complex shaped product from its data, layer by layer, with high precision and much less material wastage. As compared to the conventional manufacturing process, there are many positive environmental advantages of additive manufacturing technologies. Most importantly, there is less waste of raw material and the use of new and smart materials. In this work, we first focused on creating the composite material utilizing the Hand Lay-Up method with materials such as Carbon Fiber/Epoxy Composite with Copper Oxide (CuO) Nanoparticles and Banana Glass Fiber. Following that, we readied ASTMD638 specimens for both compressive and tensile testing. We created an ASTMD638 model for the investigation's tensile and compressive tests using Solid Works design program, and we then saved the design model in STL format. This STL format was uploaded into the CURA software for slicing. The slicing model was then saved into G-code format, and it was printed in a fused deposition modeling machine. Lastly, we tested both specimens using a compressive test setup in a Universal Testing Machine model (INSTRON-3369) UTM, and the results showed 3D printed files. Keywords: Glass Fiber, Banana Fiber, Carbon Fiber, Copper Oxide Nano filler, 3D printing Machine,Corbon Fiber Filament.

EIT probe based intraoperative tissue inspection for minimally invasive surgery

Abstract Electrical Impedance Tomography (EIT) has become an integral component in the repertoire of medical imaging techniques, particularly due to its non-invasive nature and real-time imaging capabilities. Despite its potential, the application of EIT in Minimally Invasive Surgery (MIS) has been hindered by a lack of specialized electrode probes. Existing designs often compromise between invasiveness and spatial sensitivity: probes small enough for MIS often fail to provide detailed imaging, while those offering greater sensitivity are impractically large for use through a surgical trocar.
Addressing this challenge, our study presents a breakthrough in EIT probe design. The open electrode probe we have developed features a line of 16 electrodes, thoughtfully arrayed to balance the spatial demands of MIS with the need for precise imaging. Employing an advanced EIT reconstruction algorithm, our probe not only captures images that reflect the electrical characteristics of the tissues but also ensures the homogeneity of the test material is accurately represented.The versatility of our probe is demonstrated by its capacity to generate high-resolution images of subsurface anatomical structures, a feature particularly valuable during MIS where direct visual access is limited. Surgeons can rely on intraoperative EIT imaging to inform their navigation of complex anatomical landscapes, enhancing both the safety and efficacy of their procedures.
Through rigorous experimental validation using ex vivo tissue phantoms, we have established the probe's proficiency. The experiments confirmed the system's high sensitivity and precision, particularly in the critical tasks of subsurface tissue detection and surgical margin delineation.These capabilities manifest the potential of our probe to revolutionize the field of surgical imaging, providing a previously unattainable level of detail and assurance in MIS procedures.

An Investigation of Tensile, Fatigue, and Fracture Behavior of 3D-Printed Polymers

Abstract The progression of manufacturing technology has significantly benefited from the adoption of 3D printing techniques, which enable the production of parts with intricate geometries. However, it is important to acknowledge that components fabricated through this additive manufacturing method frequently manifest defects and exhibit a propensity for failure under severe conditions. Therefore, a thorough examination of the mechanical properties of these parts is essential to effectively reduce the failure. This study aimed to explore the mechanical properties of two prevalently used 3D-printed polymers, specifically Onyx and ABS, by integrating computational and experimental analyses. The experimental study utilized a material testing system and digital image correlation (DIC) technology, while the computational analysis covered the finite element (FE) modeling of the 3D-printed samples. The research focused on evaluating the tensile strength and fatigue resistance of the specimens printed in various orientations, alongside a detailed investigation of their fracture behavior. The crack propagation analysis was carried out using the DIC system and the Separating Morphing and Adaptive Re-meshing Technology (SMART) scheme in ANSYS. It was observed that upright build orientation produced the weakest samples for axial loading and specimens with notches failed earlier than those without. Moreover, Onyx was found to have a higher resistance to fracture or failure compared to ABS. The FE modeling results demonstrated strong agreement with the experimental results, validating their accuracy and reliability in characterizing the critical mechanical response of 3D-printed parts rapidly and cost-effectively.

Impact of ZnO NPs on photosynthesis in rice leaves plants grown in saline-sodic soil

Saline-sodic stress restricts the absorption of zinc by rice, consequently impacting the photosynthesis process of rice plants. In this experiment, Landrace 9 was selected as the test material and the potting method was employed to investigate the influence of ZnO nanoparticles (ZnO NPs) on zinc absorption and chlorophyll fluorescence in rice grown in saline-sodic land. The research findings demonstrate that the application of ZnO NPs proves to be more advantageous for the growth of rice in saline-sodic soil. Notably, the application of ZnO NPs significantly decreases the levels of Na+ and MDA in rice leaves in saline-sodic soil, while increasing the levels of K+ and Zn2+. Additionally, ZnO NPs enhances the content of chloroplast pigments, specific energy flux, quantum yield, and the performance of active PSII reaction center (PIABS) in rice leaves under saline-sodic stress. Furthermore, the relative variable fluorescence (WK and VJ) and quantum energy dissipation rate (φDo) of rice are also reduced. Therefore, the addition of ZnO NPs enhances the transfer of electrons and energy within the rice photosystem when subjected to saline-sodic stress. This promotes photosynthesis in rice plants growing in saline-sodic land, increasing their resistance to saline-sodic stress and ultimately facilitating their growth and development.

Does interlanguage grammar project intermediate categories? Evidence of partial representation from one‐substitution by Chinese learners of English

AbstractThis study investigates how prepositional phrases within English noun phrases (e.g., the student of physics from Italy) are represented and processed by advanced Chinese‐speaking learners of English (henceforth L2ers). Using grammaticality judgment tasks and self‐paced reading tasks, we aim to examine the offline performance and the real‐time processing of English NP‐internal PPs in relation to the head nouns. To this end, two groups of participants were instructed to provide judgments of testing materials and to respond on‐line to experimental stimuli containing the proform one. Results indicate that highly proficient L2ers processed English NP‐internal PPs utterly differently from English controls in that they demonstrated almost no sensitivity to the existence of PPs as complements following one, mostly without consciously distinguishing them from PP adjuncts. To account for L2ers’ response patterns, we propose a partial representation hypothesis (PRH), claiming that L2ers tend to disregard intermediate categories containing PP‐complements in English NPs, thus only partially representing syntactic constituents of the target language. As a structural explanation, PRH awaits further corroboration and/or falsification from more empirical studies.

Thermal Model of the AGR-5/6/7 Experiment with Offset Gas Gaps

Because of their high impact on calculated temperatures, the offset gas gaps between the graphite holder and capsule wall are evaluated for the thermal model of the Advanced Gas Reactor 5/6/7 (AGR-5/6/7) irradiation experiment. Fuel compact temperatures are a crucial factor in assessing the irradiation performance of tristructural isotropic (TRISO)-coated-particle fuel for use in high-temperature gas-cooled reactors. TRISO fuel irradiation performance is a core tenet of the U.S. Department of Energy’s Advanced Gas Reactor Fuel Development and Qualification Program, conducted in the Advanced Test Reactor at Idaho National Laboratory. Specifically, the irradiation experiments were intended to provide irradiation performance data to support fuel process development, qualify fuel for normal operating conditions, support the development of fuel performance models and codes, and provide irradiated fuel and materials for postirradiation examination and safety testing. The thermal model used to predict the fuel compact temperatures was a three-dimensional finite element model that was subject to uncertainty. The most dominant factor in the uncertainty pertaining to calculated fuel temperatures is the gas gap uncertainty, which is caused by the graphite holder nub-to-capsule wall clearance. In AGR-5/6/7 capsules, the graphite holders can be shifted away from being perfectly centered inside the stainless steel capsule walls. This is due to irradiation-induced graphite shrinkage or to insufficient nubs on the graphite holder leading to azimuthally varying gas gaps during irradiation. A method was developed to find the best offset magnitude and direction at the top and bottom of the graphite holders in Capsules 1 and 2, which experienced higher temperatures than originally predicted among the five AGR-5/6/7 axially dispersed capsules irradiated between 2018 and 2020. The differences between the calculated and the measured temperatures of thermocouples (TCs) placed in the graphite holder near the fuel compacts were used as the basis for the holder offset determination. The best-fit offset assumes that the root-mean-square error between the measured and calculated TC temperatures is a minimum value. Typical offsets in the range of 0.002 to 0.004 in. increase the fuel compact temperatures in the range of 100°C to 200°C when compared to the zero offset for Capsules 1 and 2. Additionally, because of irradiation-induced changes in the capsule geometries, the holder offsets change throughout the irradiation period.

Risk of COVID­-19 Infection among Employees of a Large Anti­tuberculosis Institution in Moscow: Survey Results

Relevance. Studying the experience of working under the conditions of COVID-19 allows us to more effectively assess the functioning of anti-epidemic measures in the event of the occurrence or threat of new pandemics, including those caused by new pathogens. The risk of contracting COVID-19 among employees of medical organizations is higher compared to the rest of the population of the metropolis, which determines the need to develop additional measures in medical organizations to protect workers. Timely assessment of risks and preventive measures during a pandemic allow building a system to protect medical institutions from various biological threats when providing medical care. Aim. Assessment of the risks of contracting COVID-19 among employees of a large anti-tuberculosis medical organization in a metropolis. Materials & Methods. A survey of employees of a large anti-tuberculosis medical organization in Moscow was conducted. The survey was conducted on 46 key questions of epidemiological history, compliance with the requirements of the sanitary and anti-epidemic regime, alleged sources of infection, prognostic risks of the occurrence and course of COVID-19. During the period from August 1 to October 1, 2022, 1225 employees of the institution were surveyed (43.8% of the total number). The survey was conducted on a voluntary basis and was anonymous. When answering questions, participants provided information about demographic factors (age, gender), place of actual residence, the fact of contracting a new coronavirus infection, frequency of laboratory testing for SARS-CoV-2, immunization against COVID-19, possible places of contact with patients with COVID-19, the use of personal protective equipment (PPE) at home and at work, the regular use of skin antiseptics, as well as other information that allowed us to establish the risks of infection of workers at home and at work. To assess the risks of infection, respondents were divided into two groups depending on the presence of a positive test for SARS-CoV-2 (group I) or its absence (group II) as of October 1, 2022. The material for testing was nasal/oropharyngeal swabs. The research of employees was carried out on the basis of the laboratory of the anti-tuberculosis medical organization, as well as in other accredited laboratories of the metropolis using the molecular genetic method, and since February 2022 also using the express method that determines the SARS-CoV-2 antigen. Results. Among the survey participants and according to the questionnaire data, 797 employees suffered from the new coronavirus infection COVID-19, and 138 (17.3%) of them had repeated cases of the disease. Factors that increase the risk of COVID-19 among personnel of anti-tuberculosis medical organizations directly involved in the fight against the new coronavirus infection have been identified. The results of the study demonstrated that important factors influencing the incidence of workers were the frequency of examination for COVID-19, the regular use of skin antiseptics, contact with sources of infection, the use of glasses for vision correction, the use of public transport and eating at work. Conclusion. The need to study the risks of contracting COVID-19 among employees of medical organization and, based on them, develop a set of additional anti-epidemic protection measures was confirmed.

Revealing microbial community characteristics in healthy human, cat and canine salivas and looking for species-specific microbes.

As two kinds of increasingly popular pets, the saliva of cat or canine is most likely to be left at the crime scene compared with the common types of body fluids in forensics. Accurately identifying the species of saliva samples found at the crime scene involving pets will help the investigators find available testing materials, reduce the consumption of reagents and save the investigative time of the case. Therefore, it is necessary to explore the characteristics and differences of saliva microbiomes of cat, canine and human. In this study, 16S rRNA gene amplicon sequencing technology was used to reveal microbial communities of saliva samples of healthy human, cat, and canine. Alpha diversity analyses indicated that canine saliva demonstrated the highest microbial diversity, followed by cat saliva, whereas human saliva microbial diversity was the lowest. The saliva samples of the three species all had their own unique microbial community compositions, and the dominant phyla of canine and cat salivas were Proteobacteria and Bacteroidete, while the dominant phyla of human saliva were Firmicutes and Proteobacteria. There was no significant statistical difference in the salivary microbiota obtained by the two collection methods (cotton swab and liquid saliva). The gender of cats and canines might have no effect on the salivary microbiota, but the different breeds had an impact on their saliva microbiomes. Principal coordinates analysis, non-metric multidimensional scaling analysis and random forest analysis all indicated significant differences in microbial community structures among the three species, allowing inference on the species sources of saliva samples by microbiome method. Differential microbial biomarkers for the salivas of three species were screened out using a variety of bioinformatics analyses, and the results demonstrated that Prevotella melaninogenica, Veillonella parvula, and Haemophilus parainfluenzae could be used as species-specific microbial biomarkers of human saliva. The detections of human species-specific microbes provide a potential method for determining human saliva.

Revealing microbial community characteristics in healthy human, cat and canine salivas and looking for species-specific microbes.

As two kinds of increasingly popular pets, the saliva of cat or canine is most likely to be left at the crime scene compared with the common types of body fluids in forensics. Accurately identifying the species of saliva samples found at the crime scene involving pets will help the investigators find available testing materials, reduce the consumption of reagents and save the investigative time of the case. Therefore, it is necessary to explore the characteristics and differences of saliva microbiomes of cat, canine and human. In this study, 16S rRNA gene amplicon sequencing technology was used to reveal microbial communities of saliva samples of healthy human, cat, and canine. Alpha diversity analyses indicated that canine saliva demonstrated the highest microbial diversity, followed by cat saliva, whereas human saliva microbial diversity was the lowest. The saliva samples of the three species all had their own unique microbial community compositions, and the dominant phyla of canine and cat salivas were Proteobacteria and Bacteroidete, while the dominant phyla of human saliva were Firmicutes and Proteobacteria. There was no significant statistical difference in the salivary microbiota obtained by the two collection methods (cotton swab and liquid saliva). The gender of cats and canines might have no effect on the salivary microbiota, but the different breeds had an impact on their saliva microbiomes. Principal coordinates analysis, non-metric multidimensional scaling analysis and random forest analysis all indicated significant differences in microbial community structures among the three species, allowing inference on the species sources of saliva samples by microbiome method. Differential microbial biomarkers for the salivas of three species were screened out using a variety of bioinformatics analyses, and the results demonstrated that Prevotella melaninogenica, Veillonella parvula, and Haemophilus parainfluenzae could be used as species-specific microbial biomarkers of human saliva. The detections of human species-specific microbes provide a potential method for determining human saliva.

Integration of Sustainable Development Goals in university STEM courses

The objectives of this study are: (1) to provide an overview of the validity of learning tools for STEM Method courses based on the Sustainable Development Goals Curriculum, (2) to assess the practicality of these learning tools, and (3) to evaluate their effectiveness in enhancing students' problem-solving abilities. This research employs the Research and Development (R&D) methodology. Data collection methods include interviews, product validation, questionnaires, and tests. Data analysis techniques encompass qualitative analysis, product validity testing, practicality testing, and effectiveness testing. The findings indicate that: (1) learning tools for STEM Method courses based on the Sustainable Development Goals curriculum comprise a Learning Plan and teaching materials, both of which are highly valid (scores of 3.4 and 3.5 respectively), (2) the practicality test of the teaching materials scored 3.73, indicating high practicality, and (3) these tools effectively improve students' problem-solving abilities, as evidenced by the experimental class outperforming the control class. In conclusion, the study demonstrates that the designed learning tools aligned with the Sustainable Development Goals Curriculum not only show strong validity and practicality but also significantly enhance students' problem-solving skills in STEM education contexts.

Modeling and Strength Calculations of Parts Made Using 3D Printing Technology and Mounted in a Custom-Made Lower Limb Exoskeleton

This study is focused on the application of 3D-printed elements and conventional elements to create a prototype of a custom-made exoskeleton for lower limb rehabilitation. The 3D-printed elements were produced by using Fused Deposition Modeling technology and acrylonitrile butadiene styrene (ABS) material. The scope of this work involved the design and construction of an exoskeleton, experimental testing of the ABS material and numerical research by using the finite element method. On the basis of the obtained results, it was possible to deduce whether the load-bearing 3D-printed elements can be used in the proposed mechanical construction. The work contains full data of the material models used in FEM modeling, taking into account the orthotropic properties of the ABS material. Various types of finite elements were used in the presented FE models. The work is a comprehensive combination of material testing issues with the possibility of implementing the obtained results in numerical strength models of machine parts.

An Optimized Approach to Multistage Permanent Deformation Testing of Granular Materials

Accurately characterizing permanent deformation in granular materials subjected to cyclic loading is crucial for pavement design. This paper introduces an alternative approach to characterizing permanent deformation in a framework that reduces the number of load cycle repetitions by applying an alternative analytical strategy based on plastic strain rate variation over time. The methodology uses a cycle-hardening approach to establish correlations between short-term (post-compaction) and long-term (shakedown state) plastic strain accumulation. This alternative approach provides an efficient means to accelerate the characterization of permanent deformation, ensuring the integrity and validity of the assessment in a more time-efficient and resource-optimized way.

Towards a more efficient and durable load classifier using machine learning analysis of electrical data generated by self-sensing asphalt mixtures

Real-time weighing plays a crucial role in various applications in the road infrastructure field, such as pavement design, pavement monitoring systems, and the development of digital twins. Innovative sensing technologies offer solutions to the limitations of traditional sensors, enhancing durability and cost-effectiveness. Current research on self-sensing technologies primarily focuses on material manufacturing, electrode embedding, and testing of piezoresistive properties. However, there is limited investigation of innovative methods for processing and analyzing electrical signals from self-sensing materials for load classification. The novelty of the present paper lies in the development of a machine learning-based load classifier using electrical data from laboratory self-sensing asphalt mixtures with carbon fibers (CFs). Specimens underwent repeated cyclic dynamic loads, and electrical signals were recorded and processed using a customized digital processing algorithm. Artificial Neural Network (ANN) and decision tree algorithms were employed to develop load classification models. Results indicate that the addition of CFs strengthens the asphalt mixture, converting it into a piezoresistive material with load-sensing capabilities. Conclusions show that while the machine learning algorithms performed satisfactorily, further research is required for optimization purposes.

Penerapan Media Pembelajaran E-Comic Dalam Meningkatkan Pemecahan Masalah Matematis Siswa

The aim of this research is to determine the development of e-comic learning media to improve the mathematics problem solving abilities of 4th grade elementary school students. The type of research carried out uses descriptive qualitative with field research methods. The type of research used is Research and Development with a 4-D design which includes a modification of the Thiagarajan model (1974:36). The stages carried out in 4-D design are the definition stage, design stage, development stage by carrying out validation tests on material, media and learning experts. After the results of the e-comics media development material test, media expert test and learning expert test were categorized as valid and feasible. Then the final stage is carried out, namely the distribution stage which aims to promote e-comic media to teachers and students. So it can be concluded that the development of e-comics media is suitable for application in mathematics learning to improve students' mathematical problem solving abilities.

Penerapan Media Pembelajaran E-Comic Dalam Meningkatkan Pemecahan Masalah Matematis Siswa

The aim of this research is to determine the development of e-comic learning media to improve the mathematics problem solving abilities of 4th grade elementary school students. The type of research carried out uses descriptive qualitative with field research methods. The type of research used is Research and Development with a 4-D design which includes a modification of the Thiagarajan model (1974:36). The stages carried out in 4-D design are the definition stage, design stage, development stage by carrying out validation tests on material, media and learning experts. After the results of the e-comics media development material test, media expert test and learning expert test were categorized as valid and feasible. Then the final stage is carried out, namely the distribution stage which aims to promote e-comic media to teachers and students. So it can be concluded that the development of e-comics media is suitable for application in mathematics learning to improve students' mathematical problem solving abilities.

Measurement of cross-section of the 6Li(d,α)4He, 6Li(d,p)7Li, 6Li(d,p)7Li*, 7Li(d,α)5He, and 7Li(d,nα)4He reactions at the deuteron energies from 0.3 MeV to 2.2 MeV

The interaction of a deuteron beam with lithium is characterized by a high yield of neutrons, high energy of neutrons and a large variety of reactions. The reliable data of the reactions cross-sections are important for many applications, including radiation testing of advanced materials and equipment. The experimental data on the cross-sections differ greatly from one author to another; for a number of reactions there is no data on the cross-section in the databases. Measurements of the reactions cross-sections were carried out at the accelerator-based neutron source VITA at Budker Institute of Nuclear Physics (Novosibirsk, Russia) using an α-spectrometer. The 6Li(d,α)4He, 6Li(d,p)7Li, 6Li(d,p)7Li*, 7Li(d,α)5He, and 7Li(d,nα)4He reactions cross-sections at deuteron energies from 0.3 MeV to 2.2 MeV have been measured. The obtained data are presented tabular form.