bluuebunny/crossref_metadata_2025 huggingface dataset:
Divergent roles of IREG/Ferroportin transporters from the nickel hyperaccumulator Leucocroton havanensis
Authors: González Dubiel Alfonso , de la Torre Vanesa Sánchez García , Fernández Rolando Reyes , Barreau Louise , Merlot Sylvain
Published: March 2024

In response to our ever‐increasing demand for metals, phytotechnologies are being developed to limit the environmental impact of conventional metal mining. However, the development of these technologies, which rely on plant species able to tolerate and accumulate metals, is partly limited by our lack of knowledge of the underlying molecular mechanisms. In this work, we aimed to better understand the role of metal transporters of the IRON REGULATED 1/FERROPORTIN (IREG/FPN) family from the nickel hyperaccumulator Leucocroton havanensis from the Euphorbiaceae family. Using transcriptomic data, we identified two homologous genes, LhavIREG1 and LhavIREG2, encoding divalent metal transporters of the IREG/FPN family. Both genes are expressed at similar levels in shoots, but LhavIREG1 shows higher expression in roots. The heterologous expression of these transporters in A. thaliana revealed that LhavIREG1 is localized to the plasma membrane, whereas LhavIREG2 is located on the vacuole. In addition, the expression of each gene induced a significant increase in nickel tolerance. Taken together, our data suggest that LhavIREG2 is involved in nickel sequestration in vacuoles of leaf cells, whereas LhavIREG1 is mainly involved in nickel translocation from roots to shoots, but could also be involved in metal sequestration in cell walls. Our results suggest that paralogous IREG/FPN transporters may play complementary roles in nickel hyperaccumulation in plants.
Diverse projected climate change scenarios affect the physiology of broccoli plants to different extents
Authors: Pineda Mónica , Barón Matilde , Pérez‐Bueno María Luisa
Published: March 2024

Climate change caused by global warming involves crucial plant growth factors such as atmospheric CO2 concentration, ambient temperature or water availability. These stressors usually co‐occur, causing intricate alterations in plant physiology and development. This work focuses on how elevated atmospheric CO2 levels, together with the concomitant high temperature, would affect the physiology of a relevant crop, such as broccoli. Particular attention has been paid to those defence mechanisms that contribute to plant fitness under abiotic stress. Results show that both photosynthesis and leaf transpiration were reduced in plants grown under climate change environments compared to those grown under current climate conditions. Furthermore, an induction of carbohydrate catabolism pointed to a redistribution from primary to secondary metabolism. This result could be related to a reinforcement of cell walls, as well as to an increase in the pool of antioxidants in the leaves. Broccoli plants, a C3 crop, grown under an intermediate condition showed activation of those adaptive mechanisms, which would contribute to coping with abiotic stress, as confirmed by reduced levels of lipid peroxidation relative to current climate conditions. On the contrary, the most severe climate change scenario exceeded the adaptive capacity of broccoli plants, as shown by the inhibition of growth and reduced vigour of plants. In conclusion, only a moderate increase in atmospheric CO2 concentration and temperature would not have a negative impact on broccoli crop yields.
Involving citizens in regulation: A comparative qualitative study of four experimentalist cases of participatory regulation in Dutch health care
Authors: de Graaff Bert , Rutz Suzanne , Stoopendaal Annemiek , van de Bovenkamp Hester
Published: March 2024

The literature on responsive regulation argues that citizens should be involved in regulatory practices to avoid capture between regulator and regulatee. It also argues that including citizens can add an important perspective to regulatory practices. However, we know little about how citizens' perspectives are brought into regulatory practices. This paper draws on existing qualitative research to compare and analyze four cases of experimental participatory regulation in Dutch health care, focusing on the theoretical assumptions that citizen involvement (a) prevents capture, and (b) stimulates the inclusion of new perspectives. Our results show that involving citizens in regulation can increase transparency and trust in regulatory practices and familiarizes regulators with other perspectives. It is, however, up to the regulator to work on deriving benefits from that involvement—not only the practical work of organizing participatory regulation, but also the conceptual work of reflecting on their own assumptions and standards. We do find evidence for weak forms of capture and argue for the need to extend capture to involve multiple actors. We reflect on these results for theory development and regulatory practice.
Deceptive choice architecture and behavioral audits: A principles‐based approach
Authors: Mills Stuart
Published: March 2024

Regulators are increasingly concerned about deceptive, online choice architecture, including dark patterns and behavioral sludge. From a behavioral science perspective, fostering a regulatory environment which reduces the economic harm caused by deceptive designs, while safeguarding the benefits of well‐meaning behavioral insights, is essential. This article argues for a principles‐based approach and proposes behavioral audits as a tool to support this approach.
Service liberalization and productivity in high‐tech firms: Evidence from China
Authors: Li Xuchao , Zhao Jing , Yang Ruomeng
Published: March 2024

This article studies the relationship between service liberalization and the productivity of high‐tech manufacturing. Examining the sudden relaxation of FDI regulation in several service sectors in China, this article finds that service liberalization improves high‐tech firms' TFP. The effect is greater in non‐SOEs, firms with a higher degree of service dependence, and firms located in regions with better institutional environments. Furthermore, after service liberalization, high‐tech firms of all sizes have more outsourcing service expenditures and spend less on intermediate inputs. Only large‐sized high‐tech firms increase their R&D expenditures to improve production efficiency.
Co‐developmental trajectories of suicidal ideation and non‐suicidal self‐injury among Chinese adolescents: Transdiagnostic predictors and association with suicide attempts
Authors: Shen Yunhong , Chen Danrui , Guo Jiaqi , Zheng Yue , Zhang Jiajing , Zhan Shiting , You Jianing
Published: March 2024

Introduction

Adolescent suicidal ideation (SI) and non‐suicidal self‐injury (NSSI) are crucial public health issues, yet their co‐developmental trajectories during early adolescence and their associations with predictors and outcomes are unclear. This study aimed to (a) identify heterogeneous co‐developmental trajectories of SI and NSSI, (b) explore associations between transdiagnostic predictors and trajectories, and (c) assess suicide attempt risk across trajectories.

Methods

Four hundred fifty‐three adolescents (Mage = 12.35 years, 48.3% boys) completed surveys at 6‐month intervals across 2 years. At Time 1 (Nov 2020), participants completed surveys encompassing SI, and NSSI, along with family, peer, and individual predictors. Subsequent surveys (Times 2–4) measured SI and NSSI, with suicide attempts queried at Time 4.

Results

Parallel process latent class growth models revealed three co‐developmental groups (i.e., Stable low NSSI and SI; Moderate‐NSSI and high‐SI, parallel decreasing; High‐NSSI and moderate‐SI, parallel increasing). Multivariate logistic regression indicated that group membership was predicted by parental rejection, parental warmth, bullying victimization, depressive and anxiety symptoms, thwarted belongingness, and perceived burdensomeness. Adolescents in the “High‐NSSI and moderate‐SI, parallel increasing” group reported the highest suicide attempt frequency.

Conclusion

These findings underscore subgroup distinctions and transdiagnostic predictors in comprehending SI and NSSI progression, emphasizing the necessity of dynamic monitoring and tailored interventions for distinct subgroup characteristics.
Negotiating over the rules of origin in regional trade agreements in Asia
Authors: Hayakawa Kazunobu , Kimura Fukunari , Mukunoki Hiroshi , Urata Shujiro
Published: March 2024

In regional trade agreements (RTAs), member countries choose a common rule of origin (RoO) for each product. This study examines the factors that influence RoOs in four ASEAN‐plus‐one RTAs, which are agreements between ASEAN and four individual countries. One unique feature is that ASEAN as a whole negotiates with a plus‐one country, which may dilute the interests of individual ASEAN countries at large. Our findings are summarised as follows. First, the more restrictive RoOs are set in the products where plus‐one countries are less competitive against most ASEAN countries. Second, the more restrictive RoOs are likely to be imposed in products that plus‐one countries protect with higher most favoured nation tariffs. These two results reflect the bargaining power among a plus‐on country and ASEAN countries and indicate that plus‐one's preference influences RoOs more strongly. Third, we find contrasting results between intermediate and final products. RoOs are likely to be less restrictive in intermediate products and more restrictive in final products when plus‐one countries have higher export competitiveness or when the majority of ASEAN countries have higher MFN tariffs.
Diamond burr debridement of calcific band keratopathy in 24 eyes of 22 horses
Authors: Jugant Sophie , Regnier Alain , Douet Jean‐Yves
Published: March 2024

Purpose

To evaluate the safety and effectiveness of diamond burr debridement (DBD) for the treatment of calcific band keratopathy (CBK) in horses.

Methods

Medical records from horses with CBK were reviewed over a period of 4 years. Diagnosis of CBK was based on slit‐lamp examination findings, and DBD was performed on standing sedated horses. Follow‐up was obtained by clinical reevaluation of the treated eyes or a telephone survey with the referring veterinarian.

Results

Twenty‐two horses of different ages (median: 11 years; range: 5–23) representing 24 CBK‐affected eyes (14 left eyes and 10 right eyes) were included in the study. The patients had a medical history of chronic and recurrent uveitis, which required repeated long‐term treatments with various combinations of ophthalmic corticosteroids. DBD alone cleared the cornea in 22 affected eyes (92%), but it was combined with blade scraping in two cases with thick calcium plaques. The postoperative medication included a topical antibiotic, atropine drops, and oral flunixin meglumine. Corneal healing was achieved in 21 eyes (87%), 5–21 days (median time 13 days) postoperatively. The three remaining horses were lost to follow‐up. Recurrence occurred in 5 of the 21 (24%) reexamined eyes, 3–12.5 weeks (median 8 weeks) postoperatively, and required a second DBD. Four of the 21 eyes ended up being enucleated due to sequelae of uveitis. The main limitations of the study include those inherent to all retrospective clinical data collections.

Conclusion

Mechanical DBD can readily and safely clear the cornea in horses with CBK, but recurrence of calcium deposition is possible.
A review of trends and applications of learning analytics in higher education in the post-pandemic era
Authors: Bunsu Christnalter , Abd Halim Noor Dayana
Published: March 2024

Learning analytics is defined as collecting, analysis, and reporting of data about learners inside a system. Users’ interaction, which is a form of digital traces can be processed and identified into pattern. In comparison with subjective methods such as surveys and questionnaires, learning analytics provide deeper insight on students’ behaviour and assist learning institution with data-informed decision-making regarding students’ learning issues. This paper reviews on existing literature on the latest application and the trends of learning analytics in higher education over the last few years, within the period of pre and post pandemic era. As online learning was adapted rapidly during the pandemic, learning analytics became an important tool to assess students’ learning. The literature review was obtained from Scopus and Web of Science databases by using Boolean search techniques with the right keywords. This study reviewed and provided a comprehensive analysis according to certain criteria of searched studies from the year 2018 to 2023. The result showed that the research trend in learning analytics was fluctuating in Scopus and gradually declining in Web of Science due to the pandemic and shifts in research interest. In this post pandemic era, Artificial Intelligence (AI) is trending upwards, and researchers are putting interest in integrating AI with learning analytics in education. As such, this paper could help educators see the trends of LA over the last few years, as well as the innovative practices recently.
Augmented Reality in Read Aloud: An English Language Interactive Engagement
Authors: Lau Lin Yin Cassandra Eva , Yang Irene
Published: March 2024

Currently, Augmented Reality (AR) technology is emerging as a popular means to encourage children to enjoy reading books. AR technology, which creates a virtual element from a real physical environment, increases a sense of connectivity between the real and the virtual world. The Read-Aloud project aimed to spark interest in reading English language storybooks among primary school children by innovating the chosen storybook with embedded AR technology. The book, 'Nyatoh the Friendly Tree,' was selected in support of United Nations Sustainable Development Goal No. 15 on the Sustainability of Life on Land, particularly focusing on issues related to trees and sustainable forests. Primary research through a simple questionnaire was distributed to the students and analysed by the researchers using a statistical percentage table. Oral feedback and interactions were observed and recorded by the researchers. A total of 160 students, with 82 aged 12 and 78 aged 10, from a government primary school in the urban city experienced AR in the read-aloud session.  The book was initially read to the students, followed by language activities and hands-on AR experiences using smartphones and physical books. All activities were conducted in smaller groups of five. The AR features 3D models of the main character and side characters, including animals from the rainforest. Comprehension questions in the form of a quiz were generated, and to expand vocabulary, audio explanations of words in animation were created. Feedback was gathered at the end of the session in two categories: (a) interest, engagement, and interaction with the story, and (b) comprehension of the language and story. Students reported positive experiences with AR in both categories and generally found the activity fun, interesting, and enjoyable and were motivated to read. While scores in the comprehension area were lower, they still indicated a positive impact of AR on vocabulary comprehension, contributing to the overall understanding of the story. Interaction with animation also plays a role in supporting the sense-making of non-verbal representation. This project demonstrated that AR holds tremendous appeal in generating interest in reading when it incorporates a modification of physical reality with virtual elements. Exploring the potential of AR in storybooks and read-aloud sessions is valuable, especially considering the benefits of reading on learners' development. The research was still in its early stages, with additional variables to be considered. Longitudinal studies could be conducted for clearer validity and reduction of the novelty effect. This includes identifying individual learning styles in software design, providing training for both teachers and students, and developing appropriate learning activities for AR applications.
Identifying the Level of Teacher's Maturity in the Impactful Technology Use (ITU) in Abu Dhabi Public Schools
Authors: Hamash Mahmoud , Mohamed Hasnah
Published: March 2024

The effectiveness of using educational technology in the education system, especially in math and science, has been the subject of many research projects due to its importance. However, it is clear that in many classrooms, teachers lack maturity in using technology effectively. Therefore, the purpose of this research is to assess the level of Impactful Technology Use (ITU) among science and math teachers in public schools in the Al Dhafra region of Abu Dhabi. A mixed-methods approach was used, specifically a concurrent triangulation design, with a sample of 89 science and math teachers selected through purposive sampling. The data collected included teacher questionnaires, lesson observation rubrics, teacher interviews, and class observations. The findings demonstrate a high level of maturity among teachers in their use of technology, as evidenced by their ability to meet the six conditions of ITU. This success can be attributed to the support and professional development provided by the Ministry of Education and other organizations. The research proposes a rubric framework for enhancing and measuring ITU, which can be utilized by education professionals to effectively incorporate technology and improve student learning outcomes. This study holds significant implications for teachers, school leadership teams, and educational governing bodies as it promotes a better understanding of how to achieve impactful use of educational technology. The researcher concludes that higher levels of teacher maturity are crucial in creating the necessary conditions for ITU and recommends further research to test and apply the findings to other subject areas.
Microwave and Reflection Properties of Palm Shell Carbonâ€“Polyester Conductive Composite Absorber
Authors: Yusof Ahmad Anas , Wan Ali Wan Khairuddin , Abd. Rahman Tharek , Nasir Ani Farid
Published: March 2024

Sifat gelombang mikro seperti kebertelusan Îµ dan tangen kehilangan tan Î´ bagi suatu komposit bersifat pengalir menggunakan campuran karbon kelapa sawit dengan resin poliyester tak tepu dikaji pada julat frekuensi 8 GHz hingga 12 GHz. Pengukuran pada Îµ and tan Î´ menekankan kepada pengaruh kandungan karbon (jisim %) menggunakan kelapa sawit yang dipirolisis pada 600Â°C, 700Â°C and 800Â°C. Peningkatan kandungan karbon di dalam setiap komposit dilihat mempengaruhi peningkatan Îµ and tan Î´. Ujian kebolehpantulan gelombang mikro turut dilakukan dengan menggunakan 30% karbon kelapa sawit di dalam panel komposit poliyester bersaiz 450 mm Ã— 450 mm. Keputusan menunjukkan ketebalan komposit telah mempengaruhi kehilangan pantulan pada frequensi gelombang mikro yang sama. Kehilangan pantulan sehingga â€“20 dB dapat dikesan pada julat frekuensi tertentu. Ini menunjukkan kemungkinan penggunaan karbon daripada sisa kelapa sawit dalam menghasilkan kehilangan yang berkesan kepada penyerapan gelombang mikro, selain menjadi alternatif dalam menghadapi peningkatan sisa kelapa sawit di dalam negara.

Kata kunci: Komposit bersifat pengalir, penyerap gelombang mikro, karbon, penggunaan sisa

The microwave properties of permittivity, Îµ and loss tangent, tan Î´ of conductive composite utilizing palm shell carbon mixed with unsaturated polyester resin were studied in the 8 to 12 GHz frequency range. The measurement of Îµ and tan Î´ emphasize on the influence of carbon concentration (mass %) of palm shell pyrolysed at 600, 700 and 800Â°C. It was observed that the increase of carbon concentration inside each measured composite influenced the increase of Îµ and tan Î´ condition. A microwave reflectivity test was also conducted by using 30% palm shell carbon in a 450 Ã— 450 mm polyester composite panel. The result indicated that the composite thickness had influenced the reflection loss curve throughout the same microwave frequencies. The reflection loss up to â€“20 dB was possible in specific effective frequency ranges. This indicated the possibility of using carbon derived from palm shell residue in providing significant loss that contributed to microwave absorption, as well as an alternative in managing the increased of oil palm shell residues throughout the country.

Key words: Conductive composite, microwave absorber, carbon, waste utilization
Extracting Soda Lignin from the Black Liquor of Oil Palm Empty Fruit Bunch
Authors: Ibrahim M. N.Mohamad , Azian H
Published: March 2024

Lignin soda telah dipencilkan daripada likuor hitam tandan sawit kosong dengan menggunakan asid sulfurik pada parameter eksperimen yang berbeza, iaitu kepekatan asid, pH, suhu dan masa pengekstrakan. Dalam kajian ini, kaedah Taguchi telah digunakan untuk menyusun faktor di atas mengikut keutamaan masingâ€“masing, berdasarkan pengaruhnya terhadap dapatan soda lignin. Susun atur ortogonal Taguchi L9 telah digunakan untuk merancang eksperimen dengan 3 tahap bagi setiap faktor. Data yang diperoleh telah dianalisis berdasarkan nisbah isyarat kepada kebisingan Taguchi dan analisis varians. Keputusan menunjukkan faktor yang paling mempengaruhi dapatan lignin ialah suhu pengekstrakan dan diikuti dengan kepekatan asid sulfurik, masa pengekstrakan dan pH. Dapatan lignin yang paling optimum, iaitu 3.016 g daripada setiap 200 mL likuor hitam diramalkan berdasarkan kepada keputusan analisis yang diperoleh. Lignin soda yang dipencilkan dalam kajian ini telah ditentusahkan menerusi analisis inframerah.

Kata kunci: Lignin soda, kaedah Taguchi, susun atur orthogonal Taguchi, dapatan lignin, dapatan lignin yang optimum

Soda lignin from oil palm empty fruit bunches was directly isolated by sulfuric acid at different experimental factors, i.e. acid concentration, pH, extraction temperature and extraction time. In this study, Taguchi Robust Design Technique was used to rank the above factors that may effect the yield of soda lignin. The Taguchi orthogonal array L9 was used for the experimental design with three levels of consideration for each factor. The response (yield of lignin) was analyzed based on the Taguchi signal to noise ratio (S/N) and analysis of variance (ANOVA). The results showed that the most notable factor influencing the yield of lignin was the extraction temperature, followed by concentration of sulfuric acid, time of extraction and pH. The optimum yield of lignin, which is 3.016 g from every 200 mL of black liquor, was then predicted based on these results. The presence of soda lignin was confirmed by FTâ€“IR analysis.

Key words: Soda lignin, Taguchi method, Taguchi orthogonal array, yield of lignin, optimum yield of lignin
A Boundary Integral Method for the Planar External Potential Flow Around Airfoils
Authors: H. M. Murid Ali , M. S. Nasser Mohamed , Amin Norsarahaida
Published: March 2024

Kertas ini membincangkan persamaan kamiran sempadan bagi masalah aliran potensi luaran di sekitar kerajang udara tanpa sudut pinggir mengekor yang terjuring. Penerbitan persamaan kamiran ini adalah berdasarkan penurunan masalah aliran potensi luaran kepada masalah Riemann luaran. Teknik penyelesaian ini berbeza daripada teknikâ€“teknik lain yang terdapat dalam literatur kerana ia melibatkan aplikasi masalah Riemann, berbanding dengan masalah Dirichlet atau Neumann seperti lazimnya. Penyelesaian persamaan kamiran mengandungi satu pemalar nyata sebarangan yang boleh ditentukan dengan mengenakan syarat Kuttaâ€“Joukowski. Persamaan kamiran tersebut kemudian diselesaikan mengunakan kaedah berangka Nystrom dengan petua knadratur Kress. Perbandingan antara kiraan berangka dan kiraan analisis bagi pekali tekanan untuk kerajang udara van de Vooren dan kerajang udara Karmanâ€“Trefftz dengan nisbah ketebalan 15% dan pelbagai sudut serang menunjukkan penghampiran yang amat baik. Keputusan berangka bagi pekali tekanan untuk kerangka NACA0012 dengan pelbagai sudut serangan juga diberikan.

Kata kunci: Persamaan kamiran sempadan, aliran potensi satah, masalah Riemann, syarat Kutta-Joukowski

This paper presents a boundary integral equation for the external potential flow problem around airfoils without cusped trailing edge angle. The derivation of the integral equation is based upon reducing the external potential flow problem to an exterior Riemann problem. The solution technique is different from the known techniques in the literature since it involves an application of the Riemann problem, instead of the usual Dirichlet or Neumann problems. The solution of the integral equation contains an arbitrary real constant, which may be determined by imposing the Kuttaâ€“Joukowski condition. The integral equation is solved numerically using the NystrÃ¶m method witn Kress quadrature rule. Comparisons between the calculated and analytical values of the pressure coefficient for the van de Vooren airfoil and the Karmanâ€“Trefftz airfoil with 15% thickness ratio and different angles of attack show very good agreement. Numerical results of the pressure coefficient for NACA0012 airfoil with different angles of attack are also presented.

Key words: Boundary integral equation, planar potential flow, Riemann problem, Kutta-Joukowski condition
The Effects of a Feedback Capacitor in a Optical Receiver Designed with Transimpedance Amplifier
Authors: Yaacob M. H. , A. Bakar A. A. , Arsad N. , Ali N. , Zakarna A. , Abdullah M. K.
Published: March 2024

Kertas teknikal ini melaporkan kesan penambahan satu kapasitor suap balik di dalam penerima optoâ€“elektrik menggunakan penguat transgalangan (TIA). TIA digunakan di dalam penerima untuk menyokong keduaâ€“dua kelajuan dan gandaan tinggi. Walau bagaimanapun, satu masalah yang dihadapi apabila membina penerima dengan TIA iaitu gandaan memuncak menghasilkan output yang tidak stabil. Satu pendekatan mudah iaitu meletakkan satu kapasitor suap balik dalam litar penguat didapati telah mengurangkan puncak tersebut dari 2 dB ke 0 dB.

Kata kunci: Optik, penerima, transgalangan, penguat, suap balik, kapasitor, gandaan, puncak

This paper reports the effect of adding a feedback capacitor in the optoâ€“electrical receiver with a transimpedance amplifier (TIA).A TIA is used in a receiver to provide for both high speed and high gain. However, there is a problem faced when developing a receiver with TIA; gain peaking, which creates an unstable output. A simple approach of placing a feedback capasitor on the amplifier was found to reduce the peaking from 2 dB down to 0 dB.

Key words: Optical, receiver, transimpedance, amplifier, feedback, capacitor, gain, peaking
Skema Penjanaan Data dan Pemberat Ujian Berasaskan Kaedah Analisis Nilai Sempadan
Authors: Shukur Zarina , Romli Rohaida , Hamdan Abdul Razak
Published: March 2024

Kertas kerja ini menjelaskan reka bentuk satu skema bagi penjanaan data dan pemberat ujian untuk memarkahkan aturcara pelajar. Penjanaan data ujian dibuat berdasarkan teknik analisisâ€“nilai sempadan (pengujian kotakâ€“hitam). Nilai pemberat akan diberikan untuk setiap data ujian berdasarkan kepada nilai kritikal bagi data ujian tersebut. Nilai pemberat yang diberi digunakan dalam pemberian markah semasa penaksiran aturcara. Skema ini telah digunakan sebagai komponen dalam Sistem Penaksiran Aturcara C, STaksirC.

Kata kunci: Data ujian, analisis nilai sempadan, pemberat ujian, aturcara C, teknik pemarkahan

This paper describes the design of a scheme to generate test data and test weight for marking studentâ€™s program. The generation of test data was based on boundary value analysis technique. Each test datum will be given a weight based on how critical the data is. The given weight was used during program assessment. This scheme has been used as one of the components in C Evaluation System, also known as STaksirC.

Key words: Test data, boundary value analysis, test weight, C program, marking technique
EFFECT OF GEOMETRY OF STENOSIS ON THE COMPUTATION OF FLOW CHARACTERISTICS OF UNSTEADY BLOOD FLOW IN A COLLAPSIBLE VESSEL
Authors: Ying Tang Aik , Mohd Noor Mohd Al-Akhbar , Mohd Yassin Airil Yasreen , Saidina Amin Norsarahaida , Abd Nazir Mohd Zhafri Jamil
Published: March 2024

This paper discusses the effect of different geometric representations of stenosis on the numerical solution of one-dimensional unsteady blood flow in stenotic blood vessel (or stenosis) taking into account fluid-structure interaction. In the formulation, a collapsible pressure-area constitutive relation is added to the coupled mass and momentum equations to allow for the interaction between the cross sectional area, volumetric flow rate and pressure of the flow and hence the prevalence of the one-dimensional fluid-structure interaction. The formulation is stabilized by employing Streamline-Upwind Petrov-Galerkin scheme. Non-reflecting boundary conditions are imposed based on the method of characteristics. Flow characteristics and the geometrical effects of the stenosis are then discussed. Numerical results show that stenosis with irregular shape is more prone to collapse as compared to the smooth one for a given baseline conditions. This study, thus, highlights the importance of representing the shape of the stenosis as close as possible as it might give information otherwise missing in the simplistic smooth representation of the stenosis.
ALUMINIUM - MODIFIED ZNO NANOPARTICLES SYNTHESIZED THROUGH CO-PRECIPITATION
Authors: H. Al-Hardan Naif , Abdul Hamid Muhammed Azmi , Firdaus-Raih Mohd , Kar Keng Lim
Published: March 2024

The co-precipitation method is commonly used to produce nanoscale particles. The method was used to produce undoped and aluminium (Al) doped Zinc Oxide (ZnO) nanoparticles with doping percentages of 0 at%, 1 at%, 3 at%, and 5 at%. The samples were thermally treated in an atmospheric environment at 600 °C. The samples are then subjected to a number of characterization processes in order to investigate the effect of Al doping on the crystal structures, morphology, and chemical composition of the particle’s surfaces. The doping process results in a polycrystalline structure of the Al doped ZnO with a predominant peak in the (101) phase. Furthermore, as doping content increased, the peak intensities of the (101) phase decreased. The results of the morphology through the field effect electron microscopy (FESEM) reveals the Al doping have a significant impact on the prepared samples.
KESAN KADAR SUAPAN DAN SALUTAN BIT PEMOTONG DAN TERHADAP KEKEMASAN PROSES PEMOTONGAN PCB
Authors: Md Din Ahmad Syazili , Abu Bakar Maria , Che Ani Fakhrozi , Riduwan Mohamad , Muhamed Mukhtar Muhamed Abdul Fatah
Published: March 2024

Suitability of cutting technology and cutting parameter is important to produce perfect PCB after cutting process. Defect such as solder mask peel off normally observed during PCB cutting using cutting bit tool. Therefore, it is essential to investigate defect occurrence to obtain suitable cutting parameters such as feed rate and type of cutting bits used to produce good PCB cutting. Different types of PCB cutting bit has been used together with different feed rate to cut the PCB. Quantitative analysis on the defect area has been adopted to represent the degree of defect. The higher normalized value of neatness, the severe the degree of the defect. Quantitative analysis shows bit cutters of WC and WC/TiN with feed rate of 10 mm/s provide minimum thickness of peel off, approximately about 13 µm and 15 µm. Meanwhile WC/TiN bit cutter with feed rate of 10 mm/s shown lowest solder mask peel off approximately 1670 µm². The quantitative value of neatness can be used as a good indicator in accessing the quality of PCB after cutting process.
EVOLUTION OF DISCRETE SEMICONDUCTOR COPPER WEDGE BOND IN BIASED TEMPERATURE HUMIDITY CHAMBER
Authors: A. Omar Abdul , Jalar Azman , A. Hamid Khirullah
Published: March 2024

The ability to provide electrolyte required in a corrosion process; and its role in facilitating the reaction is widely attributed to humidity. Although corrosion typically develop over time; its symptoms may start showing up much earlier- commonly in the form of degradation. This paper aims at documenting the symptoms- particularly surface morphology of Copper (Cu) wire in discrete semiconductor component as it evolves in a stress-accelerated environment of temperature-humidity chamber. Results gathered from the trial runs show tendencies of Cu wire to degrade in the said environment, with noticeable changes observed on Cu wire wedge bond morphology after completion of 1000 hours in temperature-humidity chamber. Apart from better understanding of how discrete semiconductor with Cu wire behaves in highly demanding end applications like automotive, data obtained also shed some light on the need to reduce probability of material degradation thru better process control and optimization; ultimately in addressing package integrity.
Mechanisms underpinning sympathoexcitation in hypoxia
Authors: Simpson Lydia L. , Stembridge Mike , Siebenmann Christoph , Moore Jonathan P. , Lawley Justin S.
Published: March 2024

Sympathoexcitation is a hallmark of hypoxic exposure, occurring acutely, as well as persisting in acclimatised lowland populations and with generational exposure in highland native populations of the Andean and Tibetan plateaus. The mechanisms mediating altitude sympathoexcitation are multifactorial, involving alterations in both peripheral autonomic reflexes and central neural pathways, and are dependent on the duration of exposure. Initially, hypoxia‐induced sympathoexcitation appears to be an adaptive response, primarily mediated by regulatory reflex mechanisms concerned with preserving systemic and cerebral tissue O2 delivery and maintaining arterial blood pressure. However, as exposure continues, sympathoexcitation is further augmented above that observed with acute exposure, despite acclimatisation processes that restore arterial oxygen content (). Under these conditions, sympathoexcitation may become maladaptive, giving rise to reduced vascular reactivity and mildly elevated blood pressure. Importantly, current evidence indicates the peripheral chemoreflex does not play a significant role in the augmentation of sympathoexcitation during altitude acclimatisation, although methodological limitations may underestimate its true contribution. Instead, processes that provide no obvious survival benefit in hypoxia appear to contribute, including elevated pulmonary arterial pressure. Nocturnal periodic breathing is also a potential mechanism contributing to altitude sympathoexcitation, although experimental studies are required. Despite recent advancements within the field, several areas remain unexplored, including the mechanisms responsible for the apparent normalisation of muscle sympathetic nerve activity during intermediate hypoxic exposures, the mechanisms accounting for persistent sympathoexcitation following descent from altitude and consideration of whether there are sex‐based differences in sympathetic regulation at altitude.

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A Nonlinear Mixed Finite Element Method for the Analysis of Flexoelectric Semiconductors
Authors: Yang Qiufeng , Li Xudong , Liu Zhaowei , Jin Feng , Qu Yilin
Published: March 2024

In this paper, we develop a nonlinear mixed finite element method for flexoelectric semiconductors and analyze the mechanically tuned redistributions of free carriers and electric currents through flexoelectric polarization in typical structures. We first present a macroscopic theory for flexoelectric semiconductors by combining flexoelectricity and nonlinear drift-diffusion theory. To use C0 continuous elements, we derive an incremental constrained weak form by introducing Langrage multipliers, in which the kinematic constraints between the displacement and its gradient are guaranteed. Based on the weak form, we established a mixed C0 continuous nine-node quadrilateral finite element as well as an iterative process for solving nonlinear boundary-value problems. The accuracy and convergence of the proposed element are validated by comparing linear finite element method results against analytical solutions for the bending of a beam. Finally, the nonlinear element method is applied to more complex problems, such as a circular ring, a plate with a hole, and an isosceles trapezoid. Results indicate that mechanical loads and doping levels have distinct influences on electric properties.
AFSD-Nets: A Physics-Informed Machine Learning Model for Predicting the Temperature Evolution During Additive Friction Stir Deposition
Authors: Shi Tony , Wu Jiajie , Ma Mason , Charles Elijah , Schmitz Tony
Published: March 2024

This study models the temperature evolution during additive friction stir deposition (AFSD) using machine learning. AFSD is a solid-state additive manufacturing technology that deposits metal using plastic flow without melting. However, the ability to predict its performance using the underlying physics is in the early stage. A physics-informed machine learning approach, AFSD-Nets, is presented here to predict temperature profiles based on the combined effects of heat generation and heat transfer. The proposed AFSD-Nets includes a set of customized neural network approximators, which are used to model the coupled temperature evolution for the tool and build during multi-layer material deposition. Experiments are designed and performed using 7075 aluminum feedstock deposited on a substrate of the same material for 30 layers. A comparison of predictions and measurements shows that the proposed AFSD-Nets approach can accurately describe and predict the temperature evolution during the AFSD process.
Control of the Weld Heterogeneity by Using a Novel Counter Variable Pin Shoulder Rotation Friction Stir Welding: A Simulation and Experimental Study
Authors: Mahto Raju Prasad , Iqbal Md Perwej , Kumari Kanchan , Pal Surjya Kanta
Published: March 2024

Friction stir welding (FSW) produces inhomogeneous mechanical and metallurgical properties in the weld, which further require post-weld processing to control the heterogeneity. In the present study, the heterogeneity in the weld is reduced through counter-variable rotation friction stir welding (CVRFSW). The material flow and temperature distribution significantly affect the inhomogeneity of the FSWed properties which has been studied by developing a three-dimensional Lagrangian method-based viscoplastic model. The material flow, strain rate, and temperature distribution in conventional FSW (CFSW) and CVRFSW are studied quantitatively. The study revealed that CVRFSW improved joint strength and reduced the inhomogeneity of temperature, strain, and hardness. At a 10% lower shoulder speed than a pin, the weld strength improved by 16%. The simulation predicted that the temperature difference between the advancing side (AS) and the retreating side (RS) was 36 °C in CFSW, which was reduced to 8 °C in CVRFSW. Material deformation in CVRFSW occurred at a strain rate more than twice that of CFSW, and the asymmetry of strain rate between AS and RS reduced to one-fifth. Microstructures and their orientations of the welds were studied in detail. These findings contribute to the understanding of CVRFSW processes for enhanced weld quality and mechanical performance for industrial applications.
Approximate Integral Method for Nonlinear Reliability Analysis
Authors: Chen Zhenzhong , Qiu Guiming , Li Xiaoke , Jin Rui
Published: March 2024

In the realm of reliability analysis methods, the first-order reliability method (FORM) exhibits excellent computational accuracy and efficiency in linear problems. However, it fails to deliver satisfactory performance in nonlinear ones. Therefore, this paper proposes an approximate integral method (AIM) to calculate the failure probability of nonlinear problems. First, based on the most probable point (MPP) of failure and the reliability index β obtained from the FORM, the limit state function (LSF) can be equivalent to an approximate parabola (AP), which divides the hypersphere space into feasible and failure domains. Secondly, through the ratio of the approximate region occupied by a parabolic curve to the entire hypersphere region, the failure probability can be calculated by integration. To avoid the computational complexity in the parabolic approximate area due to high dimensionality, this paper employs a hyper-rectangle, constructed from chord lengths corresponding to different curvatures, as a substitute for the parabolic approximate area. Additionally, a function is utilized to adjust this substitution, ensuring accuracy in the calculation. Finally, compared with the calculated result of the Monte Carlo simulation (MCS) and the FORM, the feasibility of this method can be demonstrated through five numerical examples.
Hand Vibration Reduction Using Nonlinear Vibration Absorber for the Vibro-Impact Hammer Model
Authors: Alabi Oreoluwa , Gupta SunitKumar , Barry Oumar R.
Published: March 2024

This work investigates the effectiveness of a passive vibration control device to minimize the amplitude of vibrations from a hand-held impact machine (HHIM) transmitted to a hand-arm system (HAS). For this purpose, we employ a simplified lumped parameter model of an HHIM and the hand-arm system consisting of lumped masses, springs, and viscous dampers. For a better understanding of the system dynamics, we use a vibro-impact model for a more accurate representation of HHIM–ground interactions. We then examine the effectiveness of a cubic nonlinear vibration absorber in minimizing these undesirable vibrations via a nonlinear bifurcation analysis of the system. A parametric study on the numerical bifurcation analysis of the system reveals the criticality of different design parameters of the proposed nonlinear vibration absorber on the system dynamics. Our findings demonstrate that an appropriate selection of absorber parameters could significantly change the amplitude and the periodicity of vibrations transmitted to the hand. Furthermore, we observe the existence of complex motions such as period-2, period-4, and chaotic attractors in the system for the given values of the absorber and operating parameters.
Irrational Nonlinearity Enhances the Targeted Energy Transfer in a Rotary Nonlinear Energy Sink
Authors: Treacy Collin , Stein Dalton , Chelidze David
Published: March 2024

Efficient passive vibration absorption can prevent the failure of systems without requiring sensors or energy sources. Nonlinear energy sinks (NES) have gained popularity as passive vibration absorbers due to their targeted energy transfer (TET) mechanisms that extract and dissipate vibrational energy over broad frequency ranges. In this work, the vibration suppression performance of a novel bistable rotary nonlinear energy sink (BRNES) is studied numerically in the cases of impulse and harmonic excitation. The BRNES consists of a secondary mass that connects to the primary system by a rigid arm and spring that pivot at each connection point. The spring produces an irrational nonlinear restoring force that introduces bistability and favorable oscillatory TET mechanisms. The BRNES outperforms the traditional rotary NES and, in some cases, even the bistable NES. Moreover, unlike most NESs restricted to rectilinear motion, the BRNES is efficient at multiple orientations, thus demonstrating its potential to passively suppress vibrations in any in-plane direction over broad excitation magnitude and frequency ranges.
Effects of a 10-Week Integrated Curriculum Intervention on Physical Activity, Resting Blood Pressure, Motor Skills, and Well-Being in 6- to 7-Year-Olds
Authors: Duncan Michael J. , Fitton Davies Katie , Okwose Nduka , Harwood Amy E. , Jakovljevic Djordje G.
Published: March 2024

Background: Integrated curriculum interventions have been suggested as an effective means to increase physical activity (PA) and health. The feasibility of such approaches in children living in deprivation is unknown. This study sought to pilot an integrated curriculum pedometer intervention in children living in deprivation on school-based PA, body fatness, resting blood pressure, motor skills, and well-being. Methods: Using a pilot cluster randomized intervention design, children (6–7 y old, n = 64) from 2 schools in central England undertook: (1) 10-week integrated curriculum intervention or (2) control (regular school-based activity). School-based PA, body fatness, resting blood pressure, motor skills, and well-being were assessed preintervention and postintervention. Results: For the intervention group, PA was higher on school days when children had physical education lessons or there were physically active integrated curriculum activities. Body fatness significantly decreased, and well-being and perceived physical competence increased, pre–post for the intervention group compared with the control group. Accelerometer-derived PA, motor skills, and resting blood pressure were not significantly different pre–post for intervention or control groups. Conclusions: A 10-week integrated curriculum PA intervention is feasible to conduct and can positively impact aspects of health in 6- to 7-year-old children in England.
Proportion and Correlates of Children in the US-Affiliated Pacific Region Meeting Sleep, Screen Time, and Physical Activity Guidelines
Authors: Ryan Sarah T. , Okely Anthony D. , Chong Kar Hau , Stanley Rebecca M. , Randle Melanie , Waqa Gade , Yamanaka Ashley B. , Guerrero Rachael Leon , Coleman Patricia , Shallcross Leslie , Wilkens Lynne R. , Deenik Jonathan L. , Novotny Rachel
Published: March 2024

Introduction: Limited data on 24-hour movement behaviors of children aged 5–8 years exist globally. We describe the prevalence and sociodemographic associations of meeting physical activity (PA), sedentary recreational screen time (ST), and sleep guidelines among children from 11 jurisdictions in the US-Affiliated Pacific region. Methods: Cross-sectional representative data from 1192 children aged 5–8 years living in the US-Affiliated Pacific region were drawn from the baseline 2012–2014 Children’s Healthy Living Program. Sleep and moderate- to vigorous-intensity PA were calculated from accelerometry. ST and sociodemographic data were collected from caregiver surveys. The percentage of children meeting the Asia-Pacific 24-hour movement guidelines for PA (≥60 min/d of moderate- to vigorous-intensity PA), sleep (≥9 and ≤ 11 h/d) and ST (≤2 h/d) were calculated. Generalized linear mixed models were used to examine associations with adiposity and sociodemographic variables. Results: Twenty-seven percent (95% confidence interval, 24.6–30.0) of children met integrated guidelines; 98% (96.2–98.0) met PA, 78% (75.4–80.0) met sleep, and 35% (32.6–38.0) met ST guidelines. Females (adjusted odds ratio = 1.40 [95% confidence interval, 1.03–1.91]) and those living in lower-middle-income jurisdictions (2.29 [1.49–3.54]) were more likely to meet ST guidelines. Overweight children (0.62 [0.40–0.96]), those aged 8 years (0.39 [0.22–0.69]), and children with caregivers of an education level of high school or beyond (0.44 [0.29–0.68]) were less likely to achieve ST guidelines. Children from midrange annual household incomes were less likely to meet combined guidelines (0.60 [0.39–0.92]). Conclusions: Three-quarters of children are not meeting integrated Asia-Pacific 24-hour movement guidelines. Future strategies for reducing ST and increasing integrated guidelines compliance are needed.