bluuebunny/crossref_metadata_2025 huggingface dataset:
Breastfeeding Practice and Association between Characteristics and Experiences of Mothers Living in Bangkok
Authors: Topothai Chompoonut , Topothai Thitikorn , Suphanchaimat Rapeepong , Patcharanarumol Walaiporn , Putthasri Weerasak , Hangchaowanich Yupayong , Tangcharoensathien Viroj
Published: July 2021

Although the benefits of breastfeeding are widely recognized, only 14% of mothers in Thailand exclusively breastfed their children during the first six months of their lives in 2019, which dropped from 23% in 2016. This study aimed to assess the prevalence of exclusive breastfeeding (EBF) up to six months, current breastfeeding patterns, and key determinants that influence six-month EBF among mothers residing in Bangkok, Thailand. A cross-sectional study was conducted using a self-administered questionnaire survey. In total, 676 healthy mothers living in Bangkok, whose most recent child was between 6 and 18 months old, were recruited. Descriptive statistics, univariable analysis by Chi-square test, and multivariable logistic regression were performed to assess the association between six-month EBF and maternal characteristics and experiences of using maternal health services. The prevalence of six-month EBF of infants in Bangkok was 41%. The key determinants that influenced six-month EBF included: maternal age of more than 30 years; higher education level; higher maternal income; multi-parity; exposure to breastfeeding advice during pregnancy; intention to breastfeed for a long duration (≥6 months) during pregnancy; experience of six-month EBF in the previous child. This study draws health professionals’ and policy makers’ attention to further promote breastfeeding in particular types of mothers.
Socioeconomic Status, Mental Health, and Workplace Determinants among Working Adults in Hong Kong: A Latent Class Analysis
Authors: Tong Alan C. Y. , Tsoi Emily W. S. , Mak Winnie W. S.
Published: July 2021

This study provides insights on mental health correlates and work stress patterns in a representative sample of working adults in Hong Kong using an intersectional perspective. Using data from a cross-sectional, population-based telephone survey of 1007 working adults in Hong Kong, latent class analysis was conducted to identify socioeconomic classes within the sample. Three latent classes were identified, and they differed significantly in all the SES variables. Results suggested mental health to be the lowest in Class 1, the lowest income group. The three classes did not differ from their perceived level of job demand and control in work-related stress. Predictably, the highest income group perceived the lowest level of effort-reward imbalance. The lowest paid class was also reported perceiving the lowest level of relational justice. Different barriers to mental health services were also identified. Finally, cultural implications associated with work stress patterns, research, and practice implications are discussed. This study provides an empirical foundation for future studies to investigate patterns of job stress and mental health needs in a diverse population of working adults, with a particular focus on addressing the intersectional profiles of working adults and their needs in mental health services.
Youth Leisure-Time Sedentary Behavior Questionnaire (YLSBQ): Reliability and Validity in Colombian University Students
Authors: Atencio-Osorio Miguel Alejandro , Carrillo-Arango Hugo Alejandro , Correa-Rodríguez María , Rivera Diego , Castro-Piñero José , Ramírez-Vélez Robinson
Published: July 2021

Sedentary behavior (SB) is influenced by variations in social, cultural and economic contexts. This study assesses the test–retest reliability and validity of the Youth Leisure-time Sedentary Behavior Questionnaire (YLSBQ), a self-report tool that examines total and domain-specific SB in a cohort of young adults from Colombia. A cross-sectional validation study was conducted among 447 Colombian college students (52.8% men; mean (± standard deviation) age of 19.55 ± 2.54 years). To assess the reliability of the YLSBQ, Kappa statistics (k) were used. A confirmatory factor analysis (CFA) was conducted to determine validity. The Cronbach alpha for the 12 behaviors of the YLSBQ showed a good-to-excellent internal consistency (0.867, ranging from 0.715–0.935). Intraclass correlation coefficient (ICC) indicated that 10 items (83.0%) and two items (17.0%) showed excellent and good reliability, respectively. Furthermore, ICC between the total sedentary time was 0.926 (95% confidence interval [CI] = 0.912 − 0.939), which was interpreted as excellent. The goodness-of-fit tests provided evidence that overall, a four-factor solution was an adequate fit with the time scores. In conclusion, the YLSBQ could be considered a reliable, valid and usable tool for the assessment of SB in young adults in a Latin American country. We found that the psychometric properties of the questionnaire were similar to those of the original Spanish validation study.
How Does Being Solo in Nature Affect Well-Being? Evidence from Norway, Germany and New Zealand
Authors: Petersen Evi , Bischoff Annette , Liedtke Gunnar , Martin Andrew J.
Published: July 2021

Background: Solo—being intentionally solitary in nature—is receiving growing attention as a valuable outdoor education program component. Its practice and history have been researched in the context of experiential learning, but few studies have explicitly examined how solo experiences can affect dimensions of well-being. This study investigated a broad range of well-being pathways provided by being solo, based on data from Norway, Germany, and New Zealand. Methods: Using qualitative content analysis (QCA), the solo debrief responses of 40 participants (26 females, age: 19–64 years) were analysed, applying the PERMA-V framework (emotions, engagement, relationship, meaning, achievement, and vitality). Variations in the reports were explored as a function of the national sample, gender, age, prior solo experiences and expectations. Results: The study suggests that hedonic and eudemonic well-being pathways, represented by the six PERMA-V pillars, interrelate strongly. The experience of a range of positive emotions and connecting process during solo highlights two of the most frequent findings related to well-being pathways. The secondary findings suggest minor variations in the well-being pathways for the different national samples, gender and age. Expectations and prior experiences with solo were identified as context factors with minor impact. Further, the data-driven analysis identified specific physical activities, landscape features, sense-activation, perception of time and ‘good’ weather as relevant to the specific experience. Conclusions: Solo experiences provide for well-being-related pathways in a multitude of ways, which highlights the well-being potential of solo implementation across practical fields beyond outdoor education, such as wilderness therapy, and environmental and planetary health initiatives. Future studies should continue to explore solo’s well-being potential in different settings, especially in the context of non-Western samples.
Cardiorespiratory Fitness, Blood Pressure and Ethnicity Are Related to Salivary Cortisol Responses after an Exercise Test in Children: The ExAMIN Youth SA Study
Authors: Köchli Sabrina , Botha-Le Roux Shani , Uys Aletta Sophia , Kruger Ruan
Published: July 2021

Background: Childhood elevated circulatory stress mediators such as cortisol seem to play an important role in the development of hypertension and metabolic disorders later in life. Little is known about the association of body composition, cardiorespiratory fitness (CRF), blood pressure (BP) and ethnicity with cortisol reactivity in young children. Methods: In this cross-sectional study, 324 black and 227 white school children (aged 7.4 ± 1.0 years) were screened for salivary cortisol reactivity, body mass index, BP and CRF (shuttle run) by standardised assessments for children. Results: Children in the lower cortisol reactivity percentile (<25th) had a higher heart rate (87.0 ± 12.9 bpm) and a lower CRF (3.1 ± 1.3 stages) compared to children in the upper (>25th) percentile (86.2 ± 11.5 bpm and 3.5 ± 1.7 stages, respectively). At baseline, children of black ethnicity had a higher cortisol level (p < 0.001). Immediately before the exercise test, no associations of obesity, BP, CRF and ethnicity with cortisol levels were found. In analysis of covariance (ANCOVA) we found that low CRF, high BP and black ethnicity were independently associated with lower cortisol reactivity by performing the shuttle run test (p < 0.01). Conclusion: Low CRF and high BP were associated with lower cortisol reactivity after a cardiorespiratory exercise test. Black children showed a lower cortisol reactivity which may contribute to the earlier onset of hypertension reported in black compared to white populations. Primary prevention programs need to focus on improving physical fitness to reduce the growing prevalence of cardiometabolic disorders during childhood.
Human Rights and Empowerment in Aged Care: Restraint, Consent and Dying with Dignity
Authors: Jessop Tiffany , Peisah Carmelle
Published: July 2021

The aged care system in Australia is in crisis and people living with dementia are especially vulnerable to breaches of human rights to autonomy, dignity, respect, and equitable access to the highest quality of health care including meeting needs on account of disability. To be powerful advocates for themselves and others, people with dementia and the wider community with vested interests in quality aged care must be informed about their rights and what should be expected from the system. Prior to the Australian Royal Commission into Aged Care Quality and Safety, the Empowered Project was established to empower and raise awareness amongst people with dementia and their families about changed behaviours, chemical restraint, consent, end of life care, and security of tenure. A primary care-embedded health media campaign and national seminar tour were undertaken to meet the project aims of awareness-raising and empowerment, based on 10 Essential Facts about changed behaviours and rights for people with dementia, established as part of the project. Knowledge translation was assessed to examine the need and potential benefit of such seminars. We demonstrated that this brief educational engagement improved community knowledge of these issues and provided attendees with the information and confidence to question the nature and quality of care provision. With the completion of the Royal Commission and corresponding recommendations with government, we believe the community is ready to be an active player in reframing Australia’s aged care system with a human rights approach.
Boundary Objects: Engaging and Bridging Needs of People in Participatory Research by Arts-Based Methods
Authors: Groot Barbara , Abma Tineke
Published: July 2021

Background: Participatory health research (PHR) is a research approach in which people, including hidden populations, share lived experiences about health inequities to improve their situation through collective action. Boundary objects are produced, using arts-based methods, to be heard by stakeholders. These can bring about dialogue, connection, and involvement in a mission for social justice. This study aims to gain insight into the value and ethical issues of boundary objects that address health inequalities. A qualitative evaluation is conducted on three different boundary objects, created in different participatory studies with marginalized populations (mothers in poverty, psychiatric patients, and unemployed people). A successful boundary object evokes emotions among those who created the objects and those encountering these objects. Such objects move people and create an impulse for change. The more provocative the object, the more people feel triggered to foster change. Boundary objects may cross personal boundaries and could provoke feelings of discomfort and ignorance. Therefore, it is necessary to pay attention to ethics work. Boundary objects that are made by people from hidden populations may spur actions and create influence by improving the understanding of the needs of hidden populations. A dialogue about these needs is an essential step towards social justice.
Establishing a National Community of Practice for Newborn Screening Follow-Up
Authors: Darby Erin , Thompson John , Johnson Carol , Singh Sikha , Ojodu Jelili
Published: July 2021

Newborn screening (NBS) follow-up programs in the United States are managed at the state level, leaving limited opportunities for collaboration across programs and coordinated resource sharing. The Newborn Screening Technical assistance and Evaluation Program (NewSTEPs), a program of the Association of Public Health Laboratories (APHL), has established a national community of practice for NBS follow-up by creating a network of follow-up staff and stakeholders through education and engagement opportunities. The activities of NewSTEPs in support of NBS follow-up have strengthened information dissemination, collaboration, data collection and technical assistance-driven mentorship across the national system.
Integer-Wise Functional Bootstrapping on TFHE: Applications in Secure Integer Arithmetics
Authors: Okada Hiroki , Kiyomoto Shinsaku , Cid Carlos
Published: July 2021

TFHE is a fast fully homomorphic encryption scheme proposed by Chillotti et al. in Asiacrypt’ 2018. Integer-wise TFHE is a generalized version of TFHE that can encrypt the plaintext of an integer that was implicitly presented by Chillotti et al., and Bourse et al. presented the actual form of the scheme in CRYPTO’ 2018. However, Bourse et al.’s scheme provides only homomorphic integer additions and homomorphic evaluations of a sign function. In this paper, we construct a technique for operating any 1-variable function in only one bootstrapping of the integer-wise TFHE. For applications of the scheme, we also construct a useful homomorphic evaluation of several integer arithmetics: division, equality test, and multiplication between integer and binary numbers. Our implementation results show that our homomorphic division is approximately 3.4 times faster than any existing work and that its run time is less than 1 second for 4-bit integer inputs.
Clinical Evaluation of Resin Composite CAD/CAM Restorations Placed by Undergraduate Students
Authors: Vervack Valentin , De Coster Peter , Vandeweghe Stefan
Published: July 2021

To evaluate the clinical outcomes of resin composite CAD/CAM restorations in a prospective cohort study, and to assess patient and operator satisfaction after restoration placement, 59 indirect resin composite were placed by supervised undergraduate students, of which 43 restorations were followed over a mean period of 28 months (14–44 months) and evaluated using USPHS criteria. Patient and operator satisfaction levels were assessed using a visual analogue scale (VAS) after restoration placement. A total of 37 patients and 47 restorations were included for further study. Four teeth were extracted—three due to extensive drug-induced secondary caries in the same patient, and one tooth due to large periapical periodontitis after 44 months of service. The overall survival rate was 91.4%, and success rate was 87.2%. Differences between baseline and endpoint scores were significant for marginal discoloration (p < 0.05) and adaptation (p < 0.001). Color match (p < 0.05) and surface texture (p < 0.001) differed significantly, affecting all restoration types. VAS scores for patient and operator satisfaction showed a significant rank correlation (p < 0.01), and pairwise comparison showed significant differences for mean overall patient and operator VAS scores (p < 0.001). Lava Ultimate CAD/CAM may be considered a suitable material for overlays and endocrown restorations when combined with IDS, air abrasion, and MDP-containing adhesive systems. Marginal disintegration may present in inlays and onlays over time.
Evidence of a Muscle–Brain Axis by Quantification of the Neurotrophic Myokine METRNL (Meteorin-Like Protein) in Human Cerebrospinal Fluid and Serum
Authors: Berghoff Martin , Höpfinger Alexandra , Rajendran Ranjithkumar , Karrasch Thomas , Schmid Andreas , Schäffler Andreas
Published: July 2021

Data on the quantification of the potentially neurotrophic adipo-myokine METRNL (Meteorin-like protein) in human cerebrospinal fluid (CSF) are lacking and migration of this secreted protein across the blood–brain barrier (BBB) is uncertain. In the present pilot study, METRNL concentrations were quantified by ELISA in paired serum and CSF samples of 260 patients (107 males, 153 females) undergoing neurological evaluation. METRNL was abundant in serum (801.2 ± 378.3 pg/mL) and CSF (1007.2 ± 624.2 pg/mL) with a CSF/serum ratio of 1.4 ± 0.8. Serum METRNL levels were significantly correlated (rho = +0.521) to those in CSF. CSF METRNL concentrations were significantly correlated (rho = +0.480) with albumin CSF/serum ratios. The CSF/serum ratios of METRNL and albumin were positively correlated in Reibergram analysis (rho = 0.498), indicating that raising CSF concentrations of METRNL are mediated by increasing BBB dysfunction. The CSF concentrations of METRNL strongly increased in a stepwise manner along with increasing BBB dysfunction from grade 0 to grade 3 and with rising CSF cell count. CSF/serum ratio of METRNL also increased from grade 0 (1.2 ± 0.7) to grade 3 (3.0 ± 0.2). Furthermore, CSF levels were positively correlated with age. In conclusion, METRNL is a secreted and neurotrophic myokine that crosses over the BBB. CSF concentrations of METRNL increase with BBB dysfunction.
Biological Control of Fungal Diseases by Trichoderma aggressivum f. europaeum and Its Compatibility with Fungicides
Authors: Sánchez-Montesinos Brenda , Santos Mila , Moreno-Gavíra Alejandro , Marín-Rodulfo Teresa , Gea Francisco J. , Diánez Fernando
Published: July 2021

Our purpose was to evaluate the ability of Trichoderma aggressivum f. europaeum as a biological control agent against diseases from fungal phytopathogens. Twelve isolates of T. aggressivum f. europaeum were obtained from several substrates used for Agaricus bisporus cultivation from farms in Castilla-La Mancha (Spain). Growth rates of the 12 isolates were determined, and their antagonistic activity was analysed in vitro against Botrytis cinerea, Sclerotinia sclerotiorum, Fusarium solani f. cucurbitae, Pythium aphanidermatum, Rhizoctonia solani, and Mycosphaerella melonis, and all isolates had high growth rates. T. aggressivum f. europaeum showed high antagonistic activity for different phytopathogens, greater than 80%, except for P. aphanidermatum at approximately 65%. The most effective isolate, T. aggressivum f. europaeum TAET1, inhibited B. cinerea, S. sclerotiorum, and M. melonis growth by 100% in detached leaves assay and inhibited germination of S. sclerotiorum sclerotia. Disease incidence and severity in plant assays for pathosystems ranged from 22% for F. solani to 80% for M. melonis. This isolate reduced the incidence of Podosphaera xanthii in zucchini leaves by 66.78%. The high compatibility by this isolate with fungicides could allow its use in combination with different pest management strategies. Based on the results, T. aggressivum f. europaeum TAET1 should be considered for studies in commercial greenhouses as a biological control agent.
A Polyphasic Approach to Classification and Identification of Species within the Trichophyton benhamiae Complex
Authors: Baert Frederik , Lefevere Paulien , D’hooge Elizabet , Stubbe Dirk , Packeu Ann
Published: July 2021

In recent years, considerable advances have been made in clearing up the phylogenetic relationships within the Arthrodermataceae family. However, certain closely related taxa still contain poorly resolved species boundaries. Here, we tried to elucidate the species composition of the Trichophyton benhamiae species complex using a combined approach consisting of multi-gene phylogenetic analysis based on internal transcribed spacer (ITS) and beta-tubulin (BT) gene regions, morphological analysis, and spectral comparison using MALDI-ToF. We confirmed the existence of 11 different monophyletic clades within the complex representing either species or genetically distinct groups within species. MALDI-ToF spectrometry analysis revealed that most of these clades were readily distinguishable from one another; however, some closely related sister clades, such as T. europaeum and T. japonicum, were often misidentified as their counterpart. The distinct “yellow” and “white” phenotypes of T. benhamiae do not have a clear genetic basis and should thus be considered as different morphotypes of the same species. Strains traditionally considered T. benhamiae can be divided into three main clades: (i) T. benhamiae, (ii) T. europaeum/T. japonicum, and (iii) the phylogenetically distant T. africanum. While T. europaeum and T. japonicum are distinguishable based on their genotype, spectral and morphological analysis did not provide clear delimiting characteristics.
Neuro-Ophthalmological Findings in Friedreich’s Ataxia
Authors: Rojas Pilar , de Hoz Rosa , Cadena Manuel , Salobrar-García Elena , Fernández-Albarral José A. , López-Cuenca Inés , Elvira-Hurtado Lorena , Urcelay-Segura José L. , Salazar Juan J. , Ramírez José M. , Ramírez Ana I.
Published: July 2021

Friedreich ataxia (FRDA) is a progressive neurodegenerative disease caused by a severe autosomal recessive genetic disorder of the central nervous (CNS) and peripheral nervous system (PNS), affecting children and young adults. Its onset is before 25 years of age, with mean ages of onset and death between 11 and 38 years, respectively. The incidence is 1 in 30,000–50,000 persons. It is caused, in 97% of cases, by a homozygous guanine-adenine-adenine (GAA) trinucleotide mutation in the first intron of the frataxin (FXN) gene on chromosome 9 (9q13–q1.1). The mutation of this gene causes a deficiency of frataxin, which induces an altered inflow of iron into the mitochondria, increasing the nervous system’s vulnerability to oxidative stress. The main clinical signs include spinocerebellar ataxia with sensory loss and disappearance of deep tendon reflexes, cerebellar dysarthria, cardiomyopathy, and scoliosis. Diabetes, hearing loss, and pes cavus may also occur, and although most patients with FRDA do not present with symptomatic visual impairment, 73% present with clinical neuro-ophthalmological alterations such as optic atrophy and altered eye movement, among others. This review provides a brief overview of the main aspects of FRDA and then focuses on the ocular involvement of this pathology and the possible use of retinal biomarkers.
Treatment Resistance: A Time-Based Approach for Early Identification in First Episode Psychosis
Authors: Dempster Kara , Li Annie , Sabesan Priyadharshini , Norman Ross , Palaniyappan Lena
Published: July 2021

Although approximately 1/3 of individuals with schizophrenia are Treatment Resistant (TR), identifying these subjects prospectively remains challenging. The Treatment Response and Resistance in Psychosis working group defines <20% improvement as an indicator of TR, though its utility in First Episode Schizophrenia (FES) remains unknown. In a prospective cohort of FES (n = 129) followed up for 5 years, we evaluated two improvement thresholds for ‘probable TR’; <20% and <50% based on positive, negative, and total symptoms. We ascertained (1) the ecological validity (i.e., the ability to identify an expected subgroup of 1/3rd of patients); (2) the predictive validity (i.e., ability to predict poor global functioning) and (3) the clinical utility (association with clozapine use at the 5th year). Using the criteria of a total symptom reduction of <50% or negative symptom reduction of <20% resulted in ‘probable TR’ rates of 37% and 33%, respectively. Using <20% positive or total symptoms criteria resulted in very low rates, indicating minimal utility in FES. <50% total symptom criterion best predicted the global functioning over 5 years. Clozapine use was only predicted by positive symptom criterion. Prospective characterization of TRS is possible at 6 months after FES through a time-based approach using a 50% threshold for symptom change in treatment-adherent patients.
Semi-Automatic Volumetric and Standard Three-Dimensional Measurements for Primary Tumor Evaluation and Response to Treatment Assessment in Pediatric Rhabdomyosarcoma
Authors: Gowin Ewelina , Jończyk-Potoczna Katarzyna , Sosnowska-Sienkiewicz Patrycja , Belen Larque Anna , Kurzawa Paweł , Januszkiewicz-Lewandowska Danuta
Published: July 2021

Current prognostic classification of rhabdomyosarcoma in children requires precise measurements of the tumor. The purpose of the study was to compare the standard three-dimensional (3D) measurements with semi-automatic tumor volume measurement method concerning assessment of the primary tumor size and the degree of response to treatment for rhabdomyosarcoma in children. Magnetic Resonance Imaging data on 31 children with treated rhabdomyosarcoma based on the Cooperative Weichteilsarkom Studiengruppe (CWS) guidance was evaluated. Tumor sizes were measured by two methods: 3D standard measurements and semi-automatic tumor volume measurement (VOI) at diagnosis, and after 9 and 17/18 weeks of the induction chemotherapy. Response to treatment and prediction values were assessed. The tumor volume medians calculated using VOI were significantly higher in comparison with those calculated using the 3D method both during the diagnosis as well as after 9 weeks of the chemotherapy and during the 17–18th week of the treatment. The volume measurements based on the generalized estimating equations on the VOI method were significantly better than the 3D method (p = 0.037). The volumetric measurements alone can hardly be considered an unequivocal marker used to make decisions on modification of the therapy in patients with rhabdomyosarcoma.
Omni-Channel Customer Experience (In)Consistency and Service Success: A Study Based on Polynomial Regression Analysis
Authors: Gao Wei , Fan Hua
Published: July 2021

Drawing on expectation disconfirmation theory, this study explores the dyadic nature of omni-channel consistency on customer experience. Specifically, we propose a conceptual model that focuses on a brand’s offline channel customer experience relative to that of its online channel, and test the influences of customer experience (in)consistency on customer satisfaction, which then improves repurchase intention and word-of-mouth. The results of polynomial regressions on 265 survey respondents indicate that given omni-channel customer experience inconsistency, customers prefer consistent online and offline experiences. For omni-channel consistency at lower levels of customer experience quality, customers prefer consistency at higher levels of quality. For omni-channel inconsistency where offline customer experience quality is lower than that online, customers prefer omni-channel inconsistency, where offline customer experience quality is higher than that online. These findings produce not only theoretical contributions but also insightful suggestions for how customer experience can be taken into consideration in the promotion of a brand’s omni-channel service success.
Rice Husk Research: From Environmental Pollutant to a Promising Source of Organo-Mineral Raw Materials
Authors: Satbaev Baimakhan , Yefremova Svetlana , Zharmenov Abdurassul , Kablanbekov Askhat , Yermishin Sergey , Shalabaev Nurgali , Satbaev Arsen , Khen Vitaliy
Published: July 2021

Rice husk is a large-tonnage waste left from rice production. It is not subject to humification and therefore becomes a serious environmental pollutant. Due to the presence of two essential elements—carbon and silicon—in its composition, rice husk is a promising organo-mineral raw material. The known methods for processing of rice husk are associated with the formation of even more aggressive waste. The creation of a waste-free technology for processing this plant material requires a detailed study. Rice husk of Kyzylorda oblast was studied using IR, SEM, TA, TPD-MS, EPR, and TEM methods. It was determined that under a temperature up to 500 °C, the ligno-carbohydrate component of rice husk decomposes almost completely. Three main peaks are recorded during the decomposition: hemicellulose at 200 °C, cellulose at 265 °C, and lignin at 350–360 °C. This process is endothermic. However, above of 300 °C the exothermic reactions associated with the formation of new substances and condensation processes in the solid residue begin to prevail. This explains the increase in the concentration of paramagnetic centers (PMCs) in products of rice husk carbonization in the range of up to 450 °C. Further increase in temperature leads to a decrease in the number of PMCs as a result of carbon graphite-like structures formation. The silicon–carbon product of rice husk carbonization (nanocomposite) is formed by interconnected nanoscale particles of carbon and silicon dioxide, the modification of which depends on the temperature of carbonization. The obtained data allow management of the rice husk utilization process while manufacturing products in demand based on ecofriendly technologies.
Study of Overprotective-Polarization of Steel Subjected to Cathodic Protection in Unsaturated Soil
Authors: Mahlobo Mandlenkosi G. R. , Olubambi Peter A. , Mjwana Phumlani , Jeannin Marc , Refait Philippe
Published: July 2021

Various electrochemical methods were used to understand the behavior of steel buried in unsaturated artificial soil in the presence of cathodic protection (CP) applied at polarization levels corresponding to correct CP or overprotection. Carbon steel coupons were buried for 90 days, and the steel/electrolyte interface was studied at various exposure times. The coupons remained at open circuit potential (OCP) for the first seven days before CP was applied at potentials of −1.0 and −1.2 V vs. Cu/CuSO4 for the remaining 83 days. Voltammetry revealed that the corrosion rate decreased from ~330 µm yr−1 at OCP to ~7 µm yr−1 for an applied potential of −1.0 V vs. Cu/CuSO4. CP effectiveness increased with time due to the formation of a protective layer on the steel surface. Raman spectroscopy revealed that this layer mainly consisted of magnetite. EIS confirmed the progressive increase of the protective ability of the magnetite-rich layer. At −1.2 V vs. Cu/CuSO4, the residual corrosion rate of steel fluctuated between 8 and 15 µm yr−1. EIS indicated that the protective ability of the magnetite-rich layer deteriorated after day 63. As water reduction proved significant at this potential, it is proposed that the released H2 bubbles damage the protective layer.
Ciprofloxacin-Releasing ROS-Sensitive Nanoparticles Composed of Poly(Ethylene Glycol)/Poly(D,L-lactide-co-glycolide) for Antibacterial Treatment
Authors: Song Jaeik , Kook Min-Suk , Kim Byung-Hoon , Jeong Young-IL , Oh Kyung-Jin
Published: July 2021

Since urinary tract infections (UTIs) are closely associated with oxidative stress, we developed ROS-sensitive nanoparticles for ciprofloxacin (CIP) delivery for inhibition of UTI. Poly(D,L-lactide-co-glycolide) (PLGA)- selenocystamine (PLGA-selenocystamine) conjugates were attached to methoxypoly(ethylene glycol) (PEG) tetraacid (TA) (TA-PEG) conjugates to produce a copolymer (abbreviated as LGseseTAPEG). Selenocystamine linkages were introduced between PLGA and TA to endow reactive oxygen species (ROS) sensitivity to nanoparticles. CIP-incorporated nanoparticles of LGseseTAPEG copolymer were fabricated by W/O/W/W emulsion method. CIP-incorporated nanoparticles responded to H2O2 and then their morphologies were disintegrated by incubation with H2O2. Furthermore, particle size distribution of nanoparticles was changed from mono-modal distribution pattern to multi-modal distribution pattern by addition of H2O2. CIP release from nanoparticles of LGseseTAPEG copolymer was faster in the presence of H2O2 than in the absence of it. In antibacterial study using Escherichia coli (E. coli), free CIP and free CIP plus empty nanoparticles showed dose-dependent inhibitory effect against growth of bacteria while CIP-incorporated nanoparticles have less antibacterial activity compared to free CIP. These results were due to that CIP-incorporated nanoparticles have sustained release properties. When free CIP or CIP-incorporated nanoparticles were introduced into dialysis membrane to mimic in vivo situation, CIP-incorporated nanoparticles showed superior antibacterial activity compared to free CIP. At cell viability assay, nanoparticles of LGseseTAPEG copolymer have no acute cytotoxicity against L929 mouse fibroblast cells and CCD986sk human skin fibroblast cells. We suggest LGseseTAPEG nanoparticles are a promising candidate for CIP delivery.
Translational Research for Orthopedic Bone Graft Development
Authors: Vilela Maria J. C. , Colaço Bruno J. A. , Ventura José , Monteiro Fernando J. M. , Salgado Christiane L.
Published: July 2021

Designing biomaterials for bone-substitute applications is still a challenge regarding the natural complex structure of hard tissues. Aiming at bone regeneration applications, scaffolds based on natural collagen and synthetic nanohydroxyapatite were developed, and they showed adequate mechanical and biological properties. The objective of this work was to perform and evaluate a scaled-up production process of this porous biocomposite scaffold, which promotes bone regeneration and works as a barrier for both fibrosis and the proliferation of scar tissue. The material was produced using a prototype bioreactor at an industrial scale, instead of laboratory production at the bench, in order to produce an appropriate medical device for the orthopedic market. Prototypes were produced in porous membranes that were e-beam irradiated (the sterilization process) and then analysed by scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), dynamic mechanical analysis (DMA), cytotoxicity tests with mice fibroblasts (L929), human osteoblast-like cells (MG63) and human MSC osteogenic differentiation (HBMSC) with alkaline phosphatase (ALP) activity and qPCR for osteogenic gene expression. The prototypes were also implanted into critical-size bone defects (rabbits’ tibia) for 5 and 15 weeks, and after that were analysed by microCT and histology. The tests performed for the physical characterization of the materials showed the ability of the scaffolds to absorb and retain water-based solvents, as well as adequate mechanical resistance and viscoelastic properties. The cryogels had a heteroporous morphology with microporosity and macroporosity, which are essential conditions for the interaction between the cells and materials, and which consequently promote bone regeneration. Regarding the biological studies, all of the studied cryogels were non-cytotoxic by direct or indirect contact with cells. In fact, the scaffolds promoted the proliferation of the human MSCs, as well as the expression of the osteoblastic phenotype (osteogenic differentiation). The in vivo results showed bone tissue ingrowth and the materials’ degradation, filling the critical bone defect after 15 weeks. Before and after irradiation, the studied scaffolds showed similar properties when compared to the results published in the literature. In conclusion, the material production process upscaling was optimized and the obtained prototypes showed reproducible properties relative to the bench development, and should be able to be commercialized. Therefore, it was a successful effort to harness knowledge from the basic sciences to produce a new biomedical device and enhance human health and wellbeing.
The Al Doping Effect on Epitaxial (In,Mn)As Dilute Magnetic Semiconductors Prepared by Ion Implantation and Pulsed Laser Melting
Authors: Yuan Ye , Xie Yufang , Yuan Ning , Wang Mao , Heller René , Kentsch Ulrich , Zhai Tianrui , Wang Xiaolei
Published: July 2021

One of the most attractive characteristics of diluted ferromagnetic semiconductors is the possibility to modulate their electronic and ferromagnetic properties, coupled by itinerant holes through various means. A prominent example is the modification of Curie temperature and magnetic anisotropy by ion implantation and pulsed laser melting in III–V diluted magnetic semiconductors. In this study, to the best of our knowledge, we performed, for the first time, the co-doping of (In,Mn)As diluted magnetic semiconductors by Al by co-implantation subsequently combined with a pulsed laser annealing technique. Additionally, the structural and magnetic properties were systematically investigated by gradually raising the Al implantation fluence. Unexpectedly, under a well-preserved epitaxial structure, all samples presented weaken Curie temperature, magnetization, as well as uniaxial magnetic anisotropies when more aluminum was involved. Such a phenomenon is probably due to enhanced carrier localization introduced by Al or the suppression of substitutional Mn atoms.
Study on the High-Speed Milling Performance of High-Volume Fraction SiCp/Al Composites
Authors: Cui Youzheng , Gao Shenrou , Wang Fengjuan , Hu Qingming , Xu Cheng , Xu Fengxia
Published: July 2021

Compared with other materials, high-volume fraction aluminum-based silicon carbide composites (hereinafter referred to as SiCp/Al) have many advantages, including high strength, small change in the expansion coefficient due to temperature, high wear resistance, high corrosion resistance, high fatigue resistance, low density, good dimensional stability, and thermal conductivity. SiCp/Al composites have been widely used in aerospace, ordnance, transportation service, precision instruments, and in many other fields. In this study, the ABAQUS/explicit large-scale finite element analysis platform was used to simulate the milling process of SiCp/Al composites. By changing the parameters of the tool angle, milling depth, and milling speed, the influence of these parameters on the cutting force, cutting temperature, cutting stress, and cutting chips was studied. Optimization of the parameters was based on the above change rules to obtain the best processing combination of parameters. Then, the causes of surface machining defects, such as deep pits, shallow pits, and bulges, were simulated and discussed. Finally, the best cutting parameters obtained through simulation analysis was the tool rake angle γ0 = 5°, tool clearance angle α0 = 5°, corner radius r = 0.4 mm, milling depth ap = 50 mm, and milling speed vc = 300 m/min. The optimal combination of milling parameters provides a theoretical basis for subsequent cutting.
Does Simulated Porcelain Firing Influence Corrosion Properties of Casted and Sintered CoCr Alloys?
Authors: Rylska Dorota , Sokolowski Grzegorz , Lukomska-Szymanska Monika
Published: July 2021

The aim of the study was to evaluate how heat processing used for dental porcelain firing influences the surface properties of sintered and casted CoCr alloy. Two CoCr alloys, Soft Metal LHK (milling in soft material and sintering) and MoguCera C (casting), were used for the study. The samples were examined using SEM–EDS before and after heat treatment. Next, corrosion examinations (Ecorr, jcorr, polarization curve, Ebr) were performed. Finally, the samples were evaluated under SEM. Based on the results, the following conclusions might be drawn: 1. Thermal treatment (porcelain firing) did not cause chemical impurities formation on the surface of CoCr alloy; 2. The sintered metal exhibited significantly higher corrosion resistance than the casted one due to its homogeneity of structure and chemical composition; 3. Heat treatment (porcelain firing) decreased the resistance of casted and sintered CoCr alloy to electrochemical corrosion. The reduction in corrosion resistance was significantly higher for the casted alloy than for the sintered alloy; 4. The corrosion resistance decrease might be due to an increased thickness and heterogeneity of oxide layers on the surface (especially for the casted alloy). The development of corrosion process started in the low-density areas of the oxide layers; 5. The sintered metal seems to be a favourable framework material for porcelain fused to metal crowns.
Photocurable Epoxy Acrylate Coatings Preparation by Dual Cationic and Radical Photocrosslinking
Authors: Bednarczyk Paulina , Mozelewska Karolina , Nowak Małgorzata , Czech Zbigniew
Published: July 2021

In this work, epoxy acrylate resin (EA) based on the industrial-grade bisphenol A-based epoxy resin (Ep6) and acrylic acid (AA) has been synthesized in order to develop hybrid resin comprising both epoxide group and reactive, terminal unsaturation. Obtained epoxy acrylate prepolymer was employed to formulate photocurable coating compositions containing, besides the EA binder, also cationic or radical photoinitiators. Hence, when cationic photoinitiators were applied, polyether-type polymer chains with pending acrylate groups were formed. In the case of free radical polymerization, epoxy acrylates certainly formed a polyacrylate backbone with pending epoxy groups. Owing to the presence of both epoxy and double carbon–carbon pendant groups, the reaction product exhibits photocrosslinking via two distinct mechanisms: (i) cationic ring-opening polymerization and (ii) free radical polymerization. Therefore, photopolymerization behavior of synthetized hybrid resin with various photoinitiators was determined via photo-differential scanning calorimetry (photo-DSC) and real-time infrared spectroscopy (RT-IR) methods, and properties of cured coatings were investigated. The performance of the following type of photoinitiators was tested in the cationic photopolymerization: diaryliodonium cations or triarylsulfonium cations, and the following type of photoinitiators were used to induce free radical photopolymerization: α-hydroxyketones, acylphosphine oxides, and their mixtures. Lastly, the basic physicomechanical properties of cured coatings, such as tack-free time, hardness, adhesion, gloss, and yellowness index, were evaluated. Some structural factors and parameters of cationic and radical photoinitiators and photopolymerization mechanisms affecting the epoxy acrylate hybrid coatings performance are discussed.
Effect of Ca Addition on Corrosion Behavior of Wrought AM60 Magnesium Alloy in Alkaline Solutions
Authors: Metalnikov Polina , Ben-Hamu Guy , Shin Kwang Seon , Eliezer Amir
Published: July 2021

Magnesium (Mg) alloys possess the lowest density among structural materials, and their application in the automotive and aircraft industries might enhance fuel efficiency. The mechanical properties can be improved by the addition of alloying elements. However, since Mg and its alloys are very susceptible to corrosion degradation, it is important to study the effect of these elements on the alloys’ corrosion behavior. In this study, 1 wt% of calcium (Ca) was added to wrought AM60 Mg alloy, and the electrochemical corrosion behavior of the alloys in alkaline solutions with and without Cl− ions was compared. The corrosion behavior was investigated by means of immersion tests, gravimetric measurements and potentiodynamic polarization (PDP); the characteristics of the oxide layer were studied by electrochemical impedance spectroscopy (EIS) and X-ray photoelectron spectroscopy (XPS). The addition of Ca resulted in precipitation of the ternary aluminum-rich (Mg-Al)2Ca phase. Scanning Kelvin probe force microscope (SKPFM) identified that this phase has a cathodic behavior relative to the α-Mg matrix; hence it can serve as additional sites for initiation of pitting corrosion. As a result, the corrosion resistance of wrought AM60 alloy with 1 wt% Ca addition deteriorated in a NaCl solution. However, in the absence of Cl− ions, alloying with Ca improves the corrosion resistance of wrought AM60 alloy due to the stabilization of the corrosion products layer. The effect of long-period immersion time on the corrosion behavior and alloy oxidation is discussed.
Mechanical Properties and Microstructure of Forged Steels
Authors: Schino Andrea Di
Published: July 2021

Forged steels represent a quite interesting material family, both from a scientific and commercial point of view, following many applications they can be devoted to [...]
Microstructure Evolution and Recrystallization Temperature Change of Cold-Rolled Fe–19Mn–0.6C Twinning-Induced Plasticity Steel during Annealing
Authors: Xue Hui , Yuan Hui , Guo Kai , Zhang Zhijia , Zhang Mengmeng
Published: July 2021

Ultra-high twinning-induced plasticity (TWIP) steel is receiving increasing attention in the automobile industry. Self-designed Fe–19Mn–0.6C TWIP steel was subjected to reveal the relationship between microstructures, which were related to recrystallization starting/ending temperature and cold rolling. The results indicated that initial deformation twins, secondary deformation twins, and nano-twins were successively generated in rolled TWIP steel with the increase of cold rolling, deformation twins, and dislocations, as well as with the elongation of grains. The elements remained uniformly dispersed rather than agglomerated in the twin crystals and grain boundaries. The recrystallization starting temperature changes of TWIP steel were 500–525, 400–425, 400–415, and 400–410 °C at cold rolling deformations of 25%, 50%, 75%, and 88%, respectively. Furthermore, the obtained corresponding recrystallization ending temperature changes were 580–600, 530–550, 520–540, and 500–520 °C, respectively. The linear relationship between cold deformation and hardness suggests that cold rolling can increase dislocation density and thus facilitate improving the hardness of TWIP steel.
Study on the Influence of the Gurson–Tvergaard–Needleman Damage Model on the Fatigue Crack Growth Rate
Authors: Sérgio Edmundo R. , Antunes Fernando V. , Neto Diogo M. , Borges Micael F.
Published: July 2021

The fatigue crack growth (FCG) process is usually accessed through the stress intensity factor range, ΔK, which has some limitations. The cumulative plastic strain at the crack tip has provided results in good agreement with the experimental observations. Also, it allows understanding the crack tip phenomena leading to FCG. Plastic deformation inevitably leads to micro-porosity occurrence and damage accumulation, which can be evaluated with a damage model, such as Gurson–Tvergaard–Needleman (GTN). This study aims to access the influence of the GTN parameters, related to growth and nucleation of micro-voids, on the predicted crack growth rate. The results show the connection between the porosity values and the crack closure level. Although the effect of the porosity on the plastic strain, the predicted effect of the initial porosity on the predicted crack growth rate is small. The sensitivity analysis identified the nucleation amplitude and Tvergaard’s loss of strength parameter as the main factors, whose variation leads to larger changes in the crack growth rate.
Design and Development of an Upper Limb Rehabilitative Robot with Dual Functionality
Authors: Islam Md Rasedul , Assad-Uz-Zaman Md , Brahmi Brahim , Bouteraa Yassine , Wang Inga , Rahman Mohammad Habibur
Published: July 2021

The design of an upper limb rehabilitation robot for post-stroke patients is considered a benchmark problem regarding improving functionality and ensuring better human–robot interaction (HRI). Existing upper limb robots perform either joint-based exercises (exoskeleton-type functionality) or end-point exercises (end-effector-type functionality). Patients may need both kinds of exercises, depending on the type, level, and degree of impairments. This work focused on designing and developing a seven-degrees-of-freedom (DoFs) upper-limb rehabilitation exoskeleton called ‘u-Rob’ that functions as both exoskeleton and end-effector types device. Furthermore, HRI can be improved by monitoring the interaction forces between the robot and the wearer. Existing upper limb robots lack the ability to monitor interaction forces during passive rehabilitation exercises; measuring upper arm forces is also absent in the existing devices. This research work aimed to develop an innovative sensorized upper arm cuff to measure the wearer’s interaction forces in the upper arm. A PID control technique was implemented for both joint-based and end-point exercises. The experimental results validated both types of functionality of the developed robot.