bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparing the Effectiveness of Brain Exercise and Educational Games on Improving Students' Attention: A Follow-Up Study
Authors: Rostaminezhad Bahareh , Arazeshi Negar , Molanorouzi Keyvan , Entezari Khorasani Zahra
Published: July 2024

bjective: The present study aimed to compare the effectiveness of brain exercise and educational games on improving the attention of 8-10-year-old students through a two-month follow-up study. Methods and Materials: The present study is experimental research with a pretest-posttest-follow-up design, including a control group and two experimental groups. The research population comprised all 8-10-year-old female students in Ahvaz during the 2022-2023 academic year. From this population, 114 individuals were selected as the research sample. However, three participants were excluded from the study due to irregular attendance in educational sessions. The study included three groups: control, brain exercise, and educational games. The brain exercise group underwent 20 sessions, each lasting 20 minutes twice a week, with each exercise lasting between 30 to 40 seconds for children (Brown, 2012). Additionally, the educational games group participated in activities twice a week for 8 weeks, with each session lasting between 30 to 45 minutes. The games included: 1) Handclap, 2) Picture completion, 3) Role-playing, 4) Drawing with closed eyes, 5) Thankfulness, 6) Two wrists, one wrist, 7) Clay modeling, 8) Finding geometric shapes (Jafari, 2014). Participants in the control group did not receive any intervention. The Souri and Ourki Attention Questionnaire (2014) was used to assess attention in three stages (before, after intervention, and two-month follow-up). Findings: The results of the Bonferroni follow-up test indicated no significant difference between the effects of brain exercise and educational games on improving the attention of 8-10-year-old students (p>0.05). However, there was a significant difference between the post-test scores of each group compared to the pretest stage (p<0.01). Conclusion: Overall, the results of the present study suggest that both brain exercise and educational games can be beneficial methods for improving both voluntary and involuntary attention in elementary school students.
The Impact of Citizenship Education on Students' Behavior
Authors: Hamedi Afifeh , Afrasyabi Farangis
Published: July 2024

Objective: The objective of this study was to evaluate the impact of a Citizenship Education Program on seventh-grade female students' aggression levels and problem-solving skills in Gachsaran. Methods and Materials: This randomized controlled trial involved 30 seventh-grade female students randomly assigned to either an intervention group or a control group, each consisting of 15 participants. The intervention group participated in a Citizenship Education Program consisting of ten 75-minute sessions over ten weeks, while the control group received no intervention. Data were collected using the Buss-Perry Aggression Questionnaire (BPAQ) and the Social Problem-Solving Inventory-Revised (SPSI-R) at three time points: pre-intervention, post-intervention, and five-month follow-up. Data analysis included analysis of variance (ANOVA) with repeated measures and Bonferroni post-hoc tests, conducted using SPSS version 27. Findings: The results indicated a significant reduction in aggression and a significant improvement in problem-solving skills in the intervention group compared to the control group. Descriptive statistics showed that the intervention group's mean aggression score decreased from 45.67 (SD = 5.21) to 32.45 (SD = 4.78) post-intervention, and further to 30.12 (SD = 4.45) at follow-up. Problem-solving skills increased from a mean score of 50.89 (SD = 6.12) to 68.23 (SD = 5.67) post-intervention, and further to 70.45 (SD = 5.78) at follow-up. ANOVA results confirmed significant effects for time, group, and time x group interaction (p < .001). Bonferroni post-hoc tests indicated significant differences between pre-intervention and post-intervention, and pre-intervention and follow-up for both variables. Conclusion: The Citizenship Education Program significantly reduced aggression and improved problem-solving skills among seventh-grade female students, with sustained effects observed at a five-month follow-up. These findings suggest that integrating citizenship education into the curriculum can effectively enhance students' social-emotional competencies and responsible behavior.
Perceptions of Childcare and Parenting Support among Working Parents
Authors: Aghaziarati Ali , Faramarzi Salar
Published: July 2024

Objective: The objective of this study was to explore the perceptions of childcare and parenting support among working parents. Method: This qualitative study employed semi-structured interviews with 20 working parents from diverse professional backgrounds. Participants were selected using purposive sampling to ensure a balanced representation of genders and a variety of family structures. The interviews were conducted either in person or via video conferencing, lasting between 45 and 60 minutes. Data were analyzed thematically using NVivo software, following a systematic coding process to identify key themes and patterns. The final sample size was determined by theoretical saturation. Results: Three main themes emerged from the analysis: experiences with current childcare arrangements, challenges in balancing work and parenting responsibilities, and access to and satisfaction with parenting support resources. Parents reported limited availability and high costs of childcare, concerns about quality, and a need for flexible services. Challenges included time management, employer support, stress, and the impact on career advancement. Informal support networks, such as family and friends, played a crucial role, while formal support services were beneficial but often underutilized due to lack of awareness. Conclusion: The study highlights the complex challenges faced by working parents in managing childcare and parenting responsibilities. Findings underscore the need for more flexible, affordable, and high-quality childcare services, along with stronger support systems within the workplace and community. By addressing these needs, policymakers, employers, and childcare providers can improve work-family balance and overall well-being for working parents. The insights gained can inform the development of more effective policies and practices, ultimately benefiting parents, children, and society.
The Way of St. James as an Educational Resource
Authors: Taboada-de-Zúñiga-Romero Pilar ,   Director USC-International Courses, Santos Xosé M. ,   Professor of Geography, USC
Published: July 2024

The Camino de Santiago has experienced a notable resurgence of pilgrimage since the last decade of the twentieth century. It has become a global phenomenon that has attracted the interest not only of people who want to walk it but also academics. Numerous studies in books and journals address issues related to the history, art, touristic opportunities, landscapes, etc. of the Camino de Santiago. In this article we propose a less common perspective: the Camino as an educational tourism resource. More specifically, the goal is learning Spanish as a foreign language through a direct experience of the pilgrimage to Compostela. We start from the idea that the Camino itself can be a useful tool for learning content material related to the history and art of Europe incorporating the dynamism of its landscapes with tourism as an avenue to approach cultural, social and economic phenomena. We use the model of the International Courses of the University of Santiago de Compostela, a public entity managed by the University, the government of Galicia, and other partner institutions, which has developed a strategy in which the Camino de Santiago becomes a tool for learning Spanish language and culture through the use of diverse elements available along the route in its varied spatial/historical dimensions.
“I just really disconnected, not completely”: Extended Walking Pilgrimage, Smart Phones, and Social Ties
Authors: E. Jenkins Kathleen ,   Professor of Sociology William & Mary
Published: July 2024

Pilgrims who engage in extended walking often note the desire to escape their everyday lives, to take on new roles, and to connect with self and unknown others in fresh ways. At the same time, researchers have stressed the weight of digital technologies and mobile media in contemporary experiences of extended walking pilgrimage. I extend the conversation by exploring the stories of pilgrims who desire to escape the everyday as they reassess their sense of self in the wake of ending intimate long-term relationships. Drawing from ten formal in-depth interviews with individuals who have engaged in extended walking on the Camino de Santiago and the Appalachian Trail, I detail the numerous social forces that intersect as pilgrims work to distance themselves from digital obligations to claim time away. I illustrate how their relationship to smart phones, economic position, life stage, and the character of their intimate relationships off the trail shape their time away from everyday life as they work to fortify self and reflect on relational loss. My findings suggest directions for new research to explore how social position and ever-present digital connections shape walking pilgrimage in a post-COVID world.
Analisis Penggunaan Metode Capital Asset Pricing Model Dalam Pengambilan Keputusan Investasi Saham
Authors: Fakhirah Zahra , Fitriani Komara Esi
Published: July 2024

This research aims to determine the conditions of returns, risks, and the categorization of efficient and inefficient stocks in the property & real estate sector companies listed on the Indonesia Stock Exchange for the period 2018-2022.
The population of this study consists of 45 property & real estate sector companies listed on the Indonesia Stock Exchange from 2018 to 2022. The sampling technique used is purposive sampling based on predefined criteria, resulting in a sample of 41 companies. The method employed in this research is a quantitative and associative approach. The data analysis technique involves using the CAPM method, which includes calculating the actual return rate (Ri), market return rate (Rm), risk-free rate (Rf), beta value of stocks (β) or risk, expected return rate [E(Ri)], conducting correlation tests, plotting the security market line graph, and categorizing stocks as efficient and inefficient based on comparisons between the actual return rate (Ri) and expected return rate [E(Ri)], beta values (β), and comparisons between the risk-free rate (Rf) and expected return rate [E(Ri)].
Based on the analysis results, it is found that 21 company stocks have an average positive actual return rate (Ri), 20 stocks have a beta value (β) greater than 1, 14 stocks have a beta value (β) less than 1, and 7 stocks have a negative beta value (β). There are 26 company stocks with a positive expected return rate [E(Ri)], indicating a strong positive correlation between the expected return rate [E(Ri)] and beta values (β) or risk.
Regarding stock categorization, out of the 41 sample companies, 11 stocks are categorized as efficient because their actual return rate (Ri) is greater than the expected return rate [E(Ri)], while 30 stocks are categorized as inefficient due to their actual return rate (Ri) being less than the expected return rate [E(Ri)]. Furthermore, 20 stocks are efficient as they have a beta value (β) greater than 1, 14 stocks are inefficient with a beta value (β) less than 1, and 7 stocks show an inverse relationship with market conditions due to their negative beta value (β). Additionally, 7 stocks are efficient as their expected return rate [E(Ri)] is greater than the risk-free rate (Rf), whereas 34 stocks are inefficient since their expected return rate [E(Ri)] is less than the risk-free rate (Rf).
Adopting Inclusive Design Principles for the Proposed North East Development Commission’s Headquarters in Maiduguri, Borno State
Authors: Alkali Abdullahi Adam , Wakawa Usman Bukar , Husaini Ibrahim Udale
Published: July 2024

This paper reports architectural research about the application of inclusive design principles in the proposed North East Development Commission Headquarters in Maiduguri, Borno State. Inclusive design aims to create spaces that are accessible, and usable, including those with disabilities, the elderly, and other vulnerable groups and appealing to diverse users, regardless of age, ability, or cultural background. The study adopted a qualitative research approach, expert interviews, and a case study of the proposed headquarters. This work reviews existing literature, demonstrating the benefits of inclusive design in public office buildings, including enhanced user satisfaction, improved employee productivity, and increased social inclusion. The findings highlight the importance of incorporating inclusive design principles, such as universal accessibility, flexible spaces, and cultural sensitivity, to create a welcoming and inclusive environment. The study provides recommendations for the design of the headquarters, emphasizing the need for a user-centered approach that prioritizes diversity, equity, and inclusion.
Estimation of the Thermal Power of Nigeria Research Reactor-1 Low Enriched Uranium Core at Half Power using the Heat Balance Approach
Authors: Ashezua J. A. , Joseph E. , Asuku A.
Published: July 2024

Reactor power estimation is crucial for the safe monitoring and evaluation of reactor operation, as the reactor power signal is normally used in the reactor automatic control system, evaluation of reactor experiments, accurate determination and calculation of fuel element burn-up as well as isotopic composition of burned fuel, normalization of calculated neutron fluxes and specifically dose rates. In this present study, the heat balance method has been applied in the estimation of the thermal power of Nigeria Research Reactor-1 (NIRR-1) specifically at the at half power. The inlet temperature, outlet temperature and temperature difference measured were of average values of 32.43 ± 1.54 oC, 43.49 ± 2.07 oC and 11.06 ± 0.53 oC, respectively. On the average, the coolant flow rate through the core was 0.3966 ± 0.0188 kg/s. The power dissipated was found to be 14.97 kW, while the total heat loss was 0.23 kW. The results obtained in this current study is consistent with that of other low enriched uranium core at half power. These results have again supported the accuracy of the heat balance method; hence, it is the method is recommended for routine estimation of Miniature Neutron Source Reactors.
KENALI DIRI DAN KELUARGA TENTANG STROKE DENGAN LANGKAH “CERDIK”
Authors: Arabta Malem Peraten Pelawi  , Roulita  , Kiki Deniati  , Nutri Yunika K Gea  , Ernauli Meliyana  , Lisna Agustina  , Lisna Nuryanti
Published: July 2024

Stroke is defined as a clinical manifestation of impaired cerebral function, either focal or generalized (global), which occurs rapidly, lasts more than 24 hours, or ends in death, without any cause other than vascular disorders being found. Stroke is the third leading cause of death after heart disease and cancer in the United States. The prevalence in America in 2005 was 2.6%. The prevalence increases according to age group, namely 0.8% at age 18-44 years, 2.7% 5 at age 45-64 years and 8.1% at age 65 years or older. Men and women have a prevalence that is not much different, namely men 2.7% and women 2.5%. The aim is to improve society regarding stroke, stroke prevention and healthy living. The research results showed that there were differences before and after health analysis results using paired sample t-test with the results of P value (0.037) < alpha (0.05). It can be concluded that there is an influence after health education has been carried out on public knowledge about stroke.
Sosialisasi Kalender Pintar Bayi Sehat (KAPAS) 1000 Hari Pertama Kehidupan Sebagai Upaya Pencegahan Stunting Pada Balita di Posyandu Nusa Indah Wilayah Kerja Puskesmas Kebon Sari Kota Surabaya
Authors: Shinta Nur Rochmayanti  , Alief Ayu Perwitasari  , Arkha Rosyaria  , Miftahul Khairoh  , Kholifatul Ummah
Published: July 2024

Stunting merupakan kondisi gagal tumbuh kembang pada anak akibat dari malnutrisi kronis pada waktu lama, sehingga intervensi pada 1000 hari pertama kehidupan sangat penting mencegah stunting. Tujuan dari pengabdian masyarakat ini untuk meningkatkan pengetahuan ibu hamil tentang gizi selama kehamilan, ASI Eksklusif dan pemberian MP-ASI dengan menggunakan media edukasi Kalender Pintar Bayi Sehat (KAPAS). Adapun yang menjadi mitra pada pengabdian masyarakat ini adalah Posyandu Nusa Indah RT RW Kelurahan kecamatan  yang berada di wilayah kerja Puskesmas Kebonsari Kecamatan Jambangan Kota Surabaya Jawa Timur. Metode yang digunakan dalam pengabmas ini yaitu menyebarkan kuesioner (pre test), edukasi kesehatan menggunakan PPT, menyebarkan Leaflet dan Media kalender pintar bayi sehat (KAPAS) kemudian menyebarkan kuesioner (Port Test). Hasil dari pengabdian masyarakat ini adalah 50% mengalami peningkatan pengetahuan setelah diberikan pendidikan kesehatan mengenai Kalender Pintar Bayi Sehat  (KAPAS) 1000 Hari Pertama Kehidupan dan 40 % dengan pengetahuan tetap. Pengetahuan ibu sebelum diberikan penyuluhan memiliki pengetahuan baik 35 % dan kurang 65 %. Setelah diberikan penyuluhan memiliki pengetahuan baik 90 % dan kurang 10 %.
PEMBUATAN BUTIR SOAL SD BERBASIS HOTS (HIGH ORDER THINKING SKILLS) UNTUK MENILAI KOMPETENSI SISWA DALAM KURIKULUM 2013
Authors: Widodo Slamet , Rilianti Adhy Putri , Hs Atika Maulidina
Published: July 2024

Currently, teachers must have the skills to create HOTS-based questions because the government, through the revised edition of the 2013 curriculum policy, states that the taxonomy of thinking is taught at all levels of education. The aim of creating HOTS-based questions is to prepare students to have logical, critical and creative thinking qualifications that are able to foster reasoning processes based on the complexity of dynamic changes in society. The process of creating HOTS-based questions is: 1) determining the goal of the questions to be achieved by students, which consists of: a) the ability to search and study information, b) connecting various information relationships, and c) applying information to solve problems, 2) creating questions that are able to develop students' reasoning abilities, which consist of various activities, namely: a) exploring, b) analyzing, c) synthesizing, d) evaluating, e) developing reasoning abilities when obtaining information, and f) critical thinking
SOLUSI PENINGKATAN KUALITAS IMPLEMENTASI HOTS PADA PEMBELAJARAN IPA SEKOLAH DASAR
Authors: Hs Atika Maulidina
Published: July 2024

The aim of this research is to determine the urgency of HOTS in elementary school science learning, the problems in its implementation, and solutions to these problems, so that the goals of HOTS in the 21st century can be achieved. The method used is a literature study of 15 related articles to obtain information related to the objectives that have been set. The results obtained show that HOTS is very important to apply to elementary school science learning, but in its implementation there are still problems including students' lack of high-level thinking abilities, inappropriate assessments, and the use of irrelevant teaching materials. Things that can be done to solve the problem are by applying the concept of a scientific approach, changing the assessment system to an authentic assessment system, and improving the quality of teaching materials so that they are in line with HOTS and the learning objectives formulated by K13 to face the 21st century
Language Learning Through Online Collaborative Learning in SMA Negeri 6 Surakarta and SMA Negeri 1 Surakarta: A Qualitative Case Study
Authors: Astrini Atik , Agus Wijayanto  , Malikatul Laila
Published: July 2024

Language learning through online collaborative learning is a complex process because it requires thoughtful and pedagogical considerations in its design, implementation, and evaluation. To understand language in online collaborative learning, it is very important to include stakeholders' perspectives on their lived experiences. A qualitative case study was chosen to conduct this research. SMA Negeri 6 Surakarta and SMA Negeri 1 Surakarta were intentionally included in the study. The data were collected from semi-structured interviews of students and teachers and online and offline observations. The collected data were analyzed using the method of constant comparative analysis. The results clarified that several proactive supports (social, pedagogical and technical support) play a crucial role in promoting meaningful collaboration. The presence of the teacher is an important factor that create the collaboration to proceed as desired setting the stage, modeling the desired expectations and guiding the students to achieve the expected results. The assignments and assessments also affect the level of student engagement; therefore, it is recommended to include both formative and summative assessments for both the product and the collaborative process. The findings of this study have implications for the scaffolding and specificity of language learning through online collaboration to support online educators.
Influence of obesity on mortality, mechanical ventilation time and mobility of critical patients with COVID-19
Authors: Martinato Luísa Helena Machado , Schmidt Débora , Piva Taila Cristina , Deponti Gracieli Nadalon , Graboski Maricene Colissi , Plentz Rodrigo Della Méa , Sbruzzi Graciele
Published: July 2024

ABSTRACT Objective To identify the influence of obesity on mortality, time to weaning from mechanical ventilation and mobility at intensive care unit discharge in patients with COVID-19. Methods This retrospective cohort study was carried out between March and August 2020. All adult patients admitted to the intensive care unit in need of ventilatory support and confirmed to have COVID-19 were included. The outcomes included mortality, time on mechanical ventilation, and mobility at intensive care unit discharge. Results Four hundred and twenty-nine patients were included, 36.6% of whom were overweight and 43.8% of whom were obese. Compared with normal body mass index patients, overweight and obese patients had lower mortality (p = 0.002) and longer intensive care unit survival (log-rank p < 0.001). Compared with patients with a normal body mass index, overweight patients had a 36% lower risk of death (p = 0.04), while patients with obesity presented a 23% lower risk (p < 0.001). There was no association between obesity and time on mechanical ventilation. The level of mobility at intensive care unit discharge did not differ between groups and showed a moderate inverse correlation with length of stay in the intensive care unit (r = -0.461; p < 0.001). Conclusion Overweight and obese patients had lower mortality and higher intensive care unit survival rates. The duration of mechanical ventilation and mobility level at intensive care unit discharge did not differ between the groups.
PFG NMR measurements of tortuosity factors for diffusion in meso- and macropores of FCC catalysts
Authors: Vasenkov Sergey , Kortunov Pavel
Published: July 2024

Pulsed field gradient (PFG) NMR is applied to measure self-diffusion coefficients of 1,3,5 tri-isopropyl-benzene in the particles of several industrial FCC catalysts having different systems of meso- and macropores. Relating these diffusivities to the self-diffusion coefficient of 1,3,5 tri-isopropyl-benzene in the liquid phase, the tortuosity factors for diffusion in the meso- and macropores of the particles were obtained. The values of the tortuosity factors were found to increase with a increasing volumetric fraction of the small (< 20 nm) meso- and macropores in the total intraparticle volume.
benefit of microscopic measuring techniques for unveiling structure-mobility relations in molecular diffusion under confinement
Authors: Kärger Jörg
Published: July 2024

Molecular propagation under confinement reveals a multitude of peculiarities in comparison with diffusion in the bulk phase of a fluid. The present review is based on the experimental evidence of microscopic measuring techniques on tracing such phenomena. A short introduction into the fundamentals, main applications and limitations of pulsed field gradient NMR as the probably most versatile technique for in-situ diffusion measurements in complex systems shall be given. The information provided by this technique is complemented by investigations using interference and IR microscopy. Confinement is considered to occur by both host–guest interactions and the formation of internal boundaries. In several cases the experimental studies are shown to give rise to quite general theoretical considerations, just like – vice versa– there is a multitude of theoretical predictions waiting for their experimental confirmation.
T2–T2 exchange in biofouled porous media
Authors: Hornemann Jennifer A. , Codd Sarah L. , Romanenko Konstantin V. , Seymour Joseph D.
Published: July 2024

Recent two dimensional nuclear magnetic resonance (NMR) techniques access exchange in pore structures through surface relaxation and diffusion based relaxation [1-4]. This research applies these techniques to measure pore changes due to biofilm growth and the impact this growth has on diffusion transport. The porous media used in this study are model beadpacks constructed from borosilicate glass beads with diameters approximately 100 um. This research shows that through changes in the relaxation rates, NMR can be used to verify biofilm growth in porous media.
proton Nuclear Magnetic Resonance spin-lattice relaxation rate of some hydrated synthetic and natural sands
Authors: Bray Christina L. , Bryant Robert G. , Cox M. J. , Ferrante Gianni , Goddard Y. , Sur Sandip , Hornack Joseph P.
Published: July 2024

The proton nuclear magnetic resonance (NMR) spin-lattice relaxation rate (R1) of hydrated sands is often used to determine porosity characteristics of near-surface aquifers using magnetic resonance sounding. Large variations in R1 have been reported in laboratory measurements on hydrated sands. To understand these variations, the R1 values of several fully hydrated sands were studied as a function of grain diameter (d) and magnetic field strength (BB0). We conclude the variations are a consequence of trace paramagnetic metals in the sand grains. R1 values from magnetic resonance sounding data should not be used to predict void size in aquifers unless the exact chemical composition of the grains is known.
Design of anisotropic diffusion hardware fiber phantoms
Authors: Fieremans Els , Deene Yves De , Baete Steven , Lemahieu Ignace
Published: July 2024

A gold standard for the validation of diffusion weighted magnetic resonance imaging (DW-MRI) in brain white matter (WM) is essential for clinical purposes but still not available. Synthetic anisotropic fiber bundles are proposed as phantoms for the validation of DW-MRI because of their well-known structure, their long preservability and the possibility to create complex geometries such as curved and fiber crossings. A crucial question is how the different material properties and size of the fiber phantoms influence the outcome of the DW-MRI experiment. Several fiber materials are compared in this study. The effect of surface relaxation and internal gradients on the SNR is evaluated. In addition, the dependency of the fiber density and fiber radius on the diffusion properties is investigated.
Signal optimization in inhomogeneous fields
Authors: Borneman Troy W. , Cory David G. , Hürlimann Martin D.
Published: July 2024

We demonstrate that pulses derived using Optimal Control Theory (OCT) techniques can be used to significantly enhance the robustness of the Carr-Purcell-Meiboom-Gill sequence (CPMG) [1,2] to inhomogeneities in the static BB0 field. By numerically inverting the Liouville - von Neumann equation, OCT pulses were derived that can be used directly in place of hard pulses in the CPMG sequence to greatly improve the bandwidth of refocusing. To retain the echo stability achieved by the Meiboom-Gill correction to the Carr-Purcell sequence, the refocusing pulses were designed to perform a unitary π-rotation as opposed to just a state inversion transfer. To illustrate this approach we present an example of optimized pulses that show an improved CPMG-like behavior with complete excitation and multiple refocusing over a bandwidth of +/- 2.6 γB1,max B with a pulse duration limited to 10 t180.
Laplace inversions applied to multi–component T2–T2 exchange experiments
Authors: Fechete Radu , Moldovan Daniel , Demco Dan Eugen , Blümich Bernhard
Published: July 2024

Two-dimensional (2D) T2-T2 molecular exchange NMR experiments with a period of magnetization storage between the two T2 relaxation encoding periods are presented. The two-dimensional time map was inverted using a fast Laplace algorithm to obtain the T2–T2 exchange map. T2–MZ(store)–T2 2D 1H NMR spectra recorded at high and low homogeneous magnetic fields of water and oil in sand, air bubbles in water and foams, exchange of liquid / foam and liquid / saturated vapours of chloroform are presented. Uni– and bi–directional exchange was observed for bubbles in water, superficial liquid shell, and foam.
Observing microstructural evolution during plaster hydration
Authors: Song Kyung-Min , Mitchell Jonathan , Gladden Lynn F.
Published: July 2024

Calcium sulphate hemihydrate (CaSO4·0.5H2O), commonly known as plaster of Paris, is used extensively in the construction, ceramics, and medical industries. There are two varieties of plaster referred to as α and β, produced by “wet” or “dry” methods respectively. Plaster hydrates to form crystalline gypsum (CaSO4·2H2O, dihydrate). We present a comparative in situ study of the microstructural changes that occur during the hydration of the two forms of plaster at a water-to-plaster ratio of w/p = 0.8 using NMR relaxometry and electron microscopy. In the α-plaster, pores evolve gradually to form a uniform, interconnected structure. In contrast, the β-plaster hydrates faster, leading to a less homogeneous product with micro-cracks resulting from rapid chemical shrinkage.
Study of local diffusion coefficients of the hydration layer of lipid vesicle bilayers
Authors: Kausik Ravinath , Armstrong Brandon D. , Han Songi
Published: July 2024

Water molecules near the surface of vesicle bilayers exhibit slow dynamics with respect to that of pure bulk water as they belong to the hydration layer. We present a unique analysis tool for the selective detection of local water of the hydration layer on the surface of unilamellar vesicles and the determination of its diffusion coefficients. We utilized stable nitroxide radicals covalently attached to the hydrophilic head groups of DOPC lipid chains that incorporate along with other lipids into vesicles. Through the use of dynamic nuclear polarization (DNP) the 1H NMR signal of local water interacting with the radical is amplified, and we present here an analysis of the local diffusion coefficients of this hydration layer.
MRI visualisation of moisture ingress into porous tissue of decayed teeth
Authors: Węglarz Władysław P. , Tanasiewicz Marta M. , Gruwel Marco L. H. , Tomanek Boguslaw
Published: July 2024

MR imaging of moisture ingression into porous tissue of decayed teeth in vitro with resolution of 30´120´180 μm3 was obtained using a 4.7 T research MRI scanner and a spinecho pulse sequence. High resolution images allowed the visualisation of the 3D structure of tooth pores and the estimation of their size and extent. Using a Single Point Imaging method, images of the mineralized tissue of teeth were obtained.
Crossover from single-file to fickian diffusion in carbon nanotubes and nanotube bundles
Authors: Liu Ying-Chun , Moore Joshua D. , Chen Qu , Roussel Thomas J. , Wang Qi , Gubbins Keith E.
Published: July 2024

The diffusion mechanism of pure component Ar and binary mixtures of Ar/Kr and Ar/Ne confined in single-walled carbon nanotubes (SWNTs) and bundles was investigated by a combined Grand Canonical Monte Carlo and molecular dynamics study. For Ar confined in SWNTs, a crossover from single-file to Fickian diffusion existed when the density of Ar was a minimum as a function of the SWNT diameter. Argon diffused by a single-file mechanism in SWNTs smaller than an accessible diameter of 1.76σAr, corresponding to (7,7), (12,0) and (8,6) SWNTs but by a Fickian mechanism for SWNTs larger in diameter. Both components in Ar/Kr mixtures had a single-file diffusional mechanism in (6,6) and (7,7) SWNTs and a Fickain mechanism for SWNTs larger in diameter. Likewise, both components in a Ar/Ne mixtures had a single-file diffusional mechanism in a (6,6) CNT, and Ar had a single-file diffusional mechanism in a (7,7) SWCNT. However, Ne in the Ar/Ne mixture exhibited Fickian diffusion in the (7,7) SWNT , which indicated bi-modal diffusion. Larger diameters of SWNTs provided Fickian diffusion for both components in an Ar/Ne mixture. Argon diffused in a (25,0) SWNT bundle (with a bimodal pore size distribution) in a bimodal mechanism, with Ar diffusing in single-file in interstitial sites and in a Fickian mechanism in inner nanotube channels. In all cases of single-file diffusion the mean-squared displacement (MSD) of the fluid molecules had a square root of time dependence, while molecules diffusing by a Fickian mechanism had a MSD with a linear time dependence.
wealth of information from transient guest profiles
Authors: Binder Tomas , Chmelik Christian , Heinke Lars , Hibbe Florian , Kärger Jörg , Titze Tobias , Tzoulaki Despina
Published: July 2024

The application of interference microscopy (IFM) and infrared microscopy (IRM) to monitor the evolution of the concentration of guest molecules in nanoporous host materials opens a new field of diffusion research in condensed matter. It combines the methodical virtues of the profiling methods of solid-state diffusion studies with the benefit of the mobility enhancement in fluids. We are going to illustrate the rich options of diffusion studies provided by this novel experimental approach.
Diffusion in a one-dimensional zeolite channel
Authors: Chatterjee Sakuntala , Schütz Gunter M.
Published: July 2024

Czaplewski et al. have demonstrated in an experiment that in the presence of strongly adsorbed hydrocarbon molecules inside a narrow, effectively one-dimensional zeolite channel, the effective desorption temperature of the weakly adsorbed hydrocarbon component is substantially increased. To explain their experimental data qualitatively, we propose a simple lattice gas model involving the diffusion of hardcore particles on a one-dimensional lattice. We present exact calculation and dynamical Monte Carlo simulations to show that taking into account an Arrhenius dependence of the single molecule diffusion coefficient on temperature, one can explain many significant features of the temperature programmed desorption profile observed in experiments.
Diffusion in glassy systems
Authors: Chaudhuri Pinaki , Berthier Ludovic , Sastry Srikanth , Kob Walter
Published: July 2024

The transport properties of glass-forming systems have many features that are not found in normal liquids. Among them is a very strong sensitivity of the relaxation times upon a change in temperature and the presence of so-called dynamical heterogeneities. In this review we discuss these unusual properties and present the results of a simple lattice gas model that helps to understand the origin of these heterogeneities from the microscopic level. Furthermore we discuss a simple analytical model, the continuous time random walk, and show that it allows to describe some aspects of the relaxation dynamics of glass-forming systems on a semi-quantitative level.
Restricted gas diffusion in a unique porous medium — human lung
Authors: Woods Jason C. , Yablonskiy Dimitriy A. , Conradi Mark S.
Published: July 2024

Restricted diffusion of gas in the lung is in many ways similar to restricted diffusion in other porous media: atomic collisions with boundaries restrict the measured value, and there is a critical dependence on the time and distance scales of the measurement. The large free diffusivity of gases allows large pores (300 microns or larger) to be studied. The high signals of hyperpolarization permit rapid diffusion imaging of the gas itself, though fluorinated hydrocarbons are simple by comparison and are a potential alternative. The complicated nature of bifurcating human lung structure provides challenges in interpretation of results of restricted diffusion. At times sufficiently short, the short-time slope of D(t)/D0 can be related to the surface-to-volume ratio - an important measure of lung structure and early emphysema. During times of a few milliseconds, diffusion anisotropy is observed, and the principal components of diffusion are related to geometric parameters of individual airways within the pulmonary acinus. This permits regional invivo lung morphometry, which gives spatial information about features and airway geometry much smaller than the imaging voxel size. The extraordinarily long T1 of 3He provides the opportunity to use stimulated echoes to probe long diffusion times and distances. Preliminary evidence indicates that for distances significantly larger than a pulmonary acinus (≥ 1 cm), the measured diffusivity is severely restricted (near 0.02 cm2/s) and is dominated by diffusion through collateral routes. This implies that the longrange ADC measurement of 3He in lungs is an exquisitely sensitive measure of collateral airway paths.
Investigations of heterogeneous diffusion based on the probability density of scaled squared displacements observed from single molecules in ultra-thin liquid films
Authors: Heidernätsch Mario , Täuber Daniela , Borczyskowski Christian von , Radons Günter
Published: July 2024

Diffusion processes in ultra-thin liquid films observed by video microscopy reveal a complex behavior. In contrast to homogeneous diffusion, dynamic and static heterogeneities are induced by layer transitions and compartments with differing diffusion coefficients, respectively. The objective of this research is the detection and distinction of such heterogeneities as well as an analysis of the underlying processes. Hence, a new method is proposed establishing a probability density of scaled squared displacements. This probability density allows for a simple and well-defined calculation of time-dependent diffusion coefficients and its fluctuations. Furthermore, by simulating a heterogeneous diffusion process these results are verified and compared to mean square displacement calculations. By means of the simulated probability density data, their dependency on the parameters is illustrated and further implications are pointed out.
Single molecule tracking of the molecular mobility in thinning liquid films on thermally grown SiO2
Authors: Täuber Daniela , Heidernätsch Mario , Bauer Michael , Radons Günter , Schuster Jörg , Borczyskowski Christian von
Published: July 2024

Diffusion coefficients obtained from weighted mean square displacements along probe molecule trajectories within ultrathin liquid TEHOS films show a correlation with film thickness. By studying cumulative distributions obtained with a time resolution of 20 ms, we could show that the diffusion is heterogeneous within our liquid films which consist of a few molecular layers only. We detected two components of the diffusion process, a slower and a faster one. Thinning of the film due to evaporation caused a slowdown of the whole diffusion process. But this resulted not from a slowdown in the two contributing components itself. Instead their relative contributions changed in favor for the slow component. We conclude that there is no pronounced difference in the diffusion coefficients attributed to the molecular layers 3 to 5 vertically above the substrate, but with the loss of upper layers along with the thinning process the concentration of probe molecules in the near surface region containing only one or two molecular layers is increased.
Incorporating internal gradient and restricted diffusion effects in Nuclear Magnetic Resonance log interpretation
Authors: Li Lilong , Chen Songhua
Published: July 2024

It is shown that internal gradient combined with the restricted diffusion effect can significantly influence the D-T2 cross plots, which are widely used for fluid typing in Nuclear Magnetic Resonance (NMR) well-logging applications. By using models that capture the most important features of the internal gradient in the sedimentary rocks, such effects can be accounted for in the D-T2 inversion process, making fluid typing more accurate.
NMR imaging of water flow in packed beds
Authors: Salameh Wassim , Leclerc Sébastien , Stemmelen Didier , Escanyé Jean-Marie
Published: July 2024

Measurements by magnetic resonance imaging (MRI) of water flow within granular porous media are presented in this study. Our goal was not only to obtain visualizations of velocity field in porous media but rather to make accurate measurements of interstitial and averaged velocities in bead packs. Two situations were examined: the first for a packed bed with a large beads diameter where it was possible to visualize the interstitial velocities and the second with a packed bed with a small beads diameter where only averaged interstitial velocities were measured.
High frequency modulated gradient spin echo diffusion measurements with chemical shift resolution
Authors: Seland John Georg
Published: July 2024

We present a Modulated Gradient Spin Echo pulse sequence that enables diffusion measurements with chemical shift resolution in the obtained spectra at higher modulation frequencies (1600 Hz) than previously obtained. The modulation is generated using a Carr-Purcell-Meiboom-Gill train of radiofrequency pulses in a constant gradient. To avoid distortions from eddy currents, a longitudinal eddy current delay was added between gradient modulation and spectrum acquisition. To suppress the effects from gradient-slicing and unwanted coherences, while maintaining high chemical shift resolution, short samples (height of 0.5 mm) were prepared in a 5 mm Shigemi™ tube. The pulse sequence was successfully tested on a sample of distilled water and a sample of a water-continuous microemulsion (Winsor’s type I).
T2D TDNMR study of skin
Authors: Bent Julian , Lee Joanna , Benson Tim
Published: July 2024

T2D TDNMR data is used to improve the assignment of the location of water in in-vitro pig skin. Whilst the corresponding 1d experiments report broad distributions of T2 and D respectively, two water components are resolved in the T2D data and are assigned as intraand extra-cellular water by considering the peak intensities in; whole defatted skin, a dermatomed slice of the top 0.4mm (mostly epidermis) and the remaining sub layer (dermis). The relative proportion of fast relaxing/fast diffusing water is largest in the epidermis section (which has a close packed cellular structure) so is assigned as intra-cellular water. Whilst there is more slowly relaxing/slowly diffusing water in the dermis section (which has fewer cells within a collagen network) so this is assigned as extra-cellular water. The observation that intra-cellular water relaxes fastest, suggests that the skin cells contain more exchangeable species, through which the water can relax, than the extra-cellular network. This assignment is supported when resolution is lost on repeated freezing, i.e. the cell walls are broken. Resolution is also lost on increasing the diffusion time from 50 to 100 and 150ms. This is likely partly due to relaxation but also due to diffusion through the cell membranes during the experiment and gives a measure of the cell wall permeability.
Energy dissipation in porous media for equilibrium and nonequilibrium translational motions
Authors: Ghadirian Bahman , Stait-Gardner Tim , Hennessy Annemarie , Price William S.
Published: July 2024

In the modelling of translational motion, the concepts of frequency-dependent (of the angular fluctuations of the velocity field) self-diffusion and the dispersion tensor are commonly used in its characterisation. Both of these parameters are related to velocity autocorrelation. An alternative means of modelling translational motion is via the equilibrium and nonequilibrium fluctuation-dissipation theorem in classical statistical mechanics. This alternative approach provides further insight into the molecular level processes occurring in the system. Here both of these theoretical fluctuation-dissipation approaches are employed to determine expressions for energy dissipation in simple equilibrium systems exhibiting asymptotic and preasymptotic diffusion and dispersion phenomena and also in a nonequilibrium preasymptotic system involving dispersion within and beyond the upper limit of heterogeneity of an isotropic porous medium. As an example the permeability of porous media due to diffusion and dispersion are studied and it is shown how a frequency-dependent permeability can be treated as a phasor.
Arsenic diffusivity study by comparison of post-Surface and post-implant diffusion in silicon with Local Density Diffusion (LDD-) model approximation
Authors: Wirbeleit Frank
Published: July 2024

The LDD model was first applied to Arsenic concentration profiles determined in surface diffusion experiments by Yoshida and Arai [1]. The new method presented is based on a mathematical convolution with a delta-function-like concentration profile. By comparing the LDD approximation of post-surface diffusion with post-implant diffusion experiments, the same LDD model parameter r is found to hold for both experimental arrangements. This work found that post-implant diffusivity is concentration dependant and this might indicate an anomalous diffusion mechanism for Arsenic.
On the measurement of surface diffusivity in disordered nanoporous carbon via molecular dynamics simulations
Authors: Mi Xi , Shi Yunfeng
Published: July 2024

Gas diffusion in nanoporous carbon includes distinct diffusion modes: surface diffusion on the pore walls and non-surface diffusion away from pore walls. We have performed molecular dynamics (MD) simulations of Ar diffusion in disordered nanoporous carbon. The main objective of this work is to separate the surface diffusion and non-surface diffusion contributions so as to comprehend their respective dependency on the porous structure and testing conditions. The nanoporous carbon sample is obtained using the quenched molecular dynamics (QMD) method. Gas flows are generated by applying a constant external force on each Ar atom, mimicking a constant chemical potential gradient. The contributions from surface diffusion and non-surface diffusion are separated according to the distance of the gas atoms away from the pore wall. We show that the surface diffusivity is affected by the interactions between gas atoms and the pore walls, the temperature, and the loading.
Quantitative recovery ordered (Q-ROSY) and diffusion
Authors: Anthonsen Henrik Walbye , Sørland Geir Humborstad , Zick Klaus , Sjöblom Johan , Simon Sébastien
Published: July 2024

Combined PFG and T1 methods for rapid acquisition of multiple scans of an NMR pulse sequence are presented. The methods apply initially two RF-pulses in combination with two magnetic field gradient pulses of opposite polarity, different strengths and different durations. The basic idea is to spoil any magnetization in any direction before letting the system recover to some degree of restoration of the thermal equilibrium magnetization. Thereafter any pulse sequence can be applied, and the next scan may be run immediately after the end of this spoiler pulse sequence. Thus one avoids the 5 times T1 delay between each scan. The method has been verified at 11.7 Tesla correlating spectral information with T1 or diffusion.