scholarly journals Characterisation and Modelling of PLA Filaments and Evolution with Time

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2899
Author(s):  
Jaime Orellana Barrasa ◽  
Ana Ferrández-Montero ◽  
Begoña Ferrari ◽  
José Ygnacio Pastor
Keyword(s):  
Building Block ◽  
Manufacturing Systems ◽  
Bulk Material ◽  
Deep Understanding ◽  
Tensile Tests ◽  
Extrusion Process ◽  
Natural Ageing ◽  
Eyring Model ◽  
One Year ◽  
Better Than

The properties of polylactic acid (PLA) filaments have not yet been analysed in detail, and they are strongly affected by the extrusion process used in some additive manufacturing systems. Here we present the mechanical, thermal, physical, and fractographical properties of an extruded filament (not the bulk material or scaffolds), the basic building block of any PLA structure printed via material extrusion. This research aims to create a reference point for the modelisation of additively manufactured structures via extrusion processes, as the main building block is characterised in detail for a deep understanding. Furthermore, we investigated the natural ageing (up to one year), the effect of the printing (extruding) temperature (180 and 190 °C), and the effect of the crosshead speed during the tensile tests (10−1 to 102 mm/min) to provide a deeper analysis of the material. The results showed that the material extruded at 190 °C performed better than the material extruded at 180 °C. However, after one hundred days of natural ageing, both materials behaved similarly. This was related to the flow-induced molecular orientation during the extrusion. The crosshead rate produced a logarithmic increase of the mechanical properties, consistent with the Eyring model. Additionally, the ageing produced significant changes in both the elastic modulus and the yield strength: from 2.4 GPa and 40 MPa, in one-day-aged samples, up to 4 GPa and 62 MPa once entirely aged. Finally, it was observed that the glass transition and the enthalpic relaxation increased with ageing, agreeing with the Kohlraushch–William–Watts model.

The Role of Chess in the Intellectual Development of Childrens from Primary School

2019 ◽  
pp. 58-62
Author(s):  
Vlad Stegariu ◽  
Simona Andreea Popușoi ◽  
Beatrice Abălașei ◽  
Nicolae Lucian Voinea ◽  
Ioan Stelescu ◽  
...  
Keyword(s):  
Cognitive Development ◽  
Primary School ◽  
Intellectual Development ◽  
Resources Allocation ◽  
Control Group ◽  
Cognitive Resources ◽  
One Year ◽  
Better Than ◽  
Chess Playing

Chess playing has a significant role in participants’ resources allocation, both at a psychological level, but mostly concerning the cognitive resources. The aim of the present study was to examine the effect of chess playing on the intellectual development of primary-class students. 67 children were tested using the Raven Standard Progressive Matrices and were distributed in three different groups according to their experience with chess, namely: the control group (formed by students with no experience with chess playing), the beginners group (students with less than one year in chess playing training) and the advanced group (children with more than two years experience with chess). Results indicated that chess playing had a significant effect on the SPM performance, indicating that those in the advanced group performed significantly better than those in the control or in the beginners group. Conclusions of this study tap into the benefits of playing chess with a focus on the children’s’ cognitive development.

A Therapeutic Trial of Fatty Acid Supplementation in Cystic Fibrosis

PEDIATRICS ◽  
1976 ◽  
Vol 57 (4) ◽  
pp. 474-479
Author(s):  
Robert B. Elliott
Keyword(s):  
Cystic Fibrosis ◽  
Fatty Acid ◽  
Clinical Course ◽  
Therapeutic Trial ◽  
Biochemical Abnormality ◽  
Fatty Acid Supplementation ◽  
Oil Emulsion ◽  
Soya Oil ◽  
One Year ◽  
Better Than

Seven children with cystic fibrosis (CF) have been treated for at least one year with intravenously administered soya oil emulsion. In all, an improvement of at least one biochemical abnormality in character with the disease appeared. The children's clinical course remains benign. This course is remarkably better than that of other children with CF treated without Intralipid in Auckland in the same period, though a placebo effect cannot be discounted. It is postulated that intravenous supplementation with essential fatty acid in CF may in turn partially correct an error of metabolism of prostaglandins present in the disease.

scholarly journals The Influence of Rooting Substrate and Growth Regulators Indol butyric Acid and Naphthalene Acetic Acid in the Number and Length of Adventitious Roots to Hardwood Cuttings in Blueberry cv. ‘Bluecrop’ (Vaccinium corymbosum L.)

2016 ◽  
Vol 4 (4) ◽  
pp. 28
Author(s):  
Sabri Braha ◽  
Petrit Rama
Keyword(s):  
Growth Regulators ◽  
Growing Season ◽  
Vaccinium Corymbosum ◽  
Naphthalene Acetic Acid ◽  
Important Variation ◽  
Physiological Processes ◽  
One Year ◽  
The Impact ◽  
Better Than

The purpose of this research is to determine the impact of the turf-only substrate and turf–perlite in the ratio 2:1 and of growth regulators in the quality of adventive roots ( the number and length) of well lignified one-year old branches without fruit buds in the Bluecrop cultivar (Vaccinium corymbosum L.) taken at the end of the latent period before budding at the February 15 th during the -2015 growing season. In order to support the increase of the number of roots and their length the hardwood cuttings are treated with different IBA and NAA concentrations (1500, 3000, 4500 ppm), while a part of cuttings were untreated control. The number and the length of roots have increased in relation to the increase of concentration from 1500 to 3000 ppm followed by a decline of these values in concentrations over 3000 ppm. Respectively, the number of roots (8) and the higher values of root length (4.6 cm) are achieved in the turf–perlite substrate, IBA 3000 ppm (compared to the turf-only substrate). The presence of perlite helps the aeration of the substrate and supports biochemical and physiological processes which lead to the inducing of adventive roots. Regarding the number and length of roots an important variation for (p<0.05) was observed between different concentrations of IBA and NAA. In general the effect of IBA was a lot better than the effect of NAA.

scholarly journals SARS-CoV-2 transmission across age groups in France and implications for control

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cécile Tran Kiem ◽  
Paolo Bosetti ◽  
Juliette Paireau ◽  
Pascal Crépey ◽  
Henrik Salje ◽  
...  
Keyword(s):  
Young Adults ◽  
Age Groups ◽  
Deep Understanding ◽  
Transmission Dynamics ◽  
Age Group ◽  
Older Individuals ◽  
Targeted Intervention ◽  
Social Distancing ◽  
Intervention Measures ◽  
Better Than

AbstractThe shielding of older individuals has been proposed to limit COVID-19 hospitalizations while relaxing general social distancing in the absence of vaccines. Evaluating such approaches requires a deep understanding of transmission dynamics across ages. Here, we use detailed age-specific case and hospitalization data to model the rebound in the French epidemic in summer 2020, characterize age-specific transmission dynamics and critically evaluate different age-targeted intervention measures in the absence of vaccines. We find that while the rebound started in young adults, it reached individuals aged ≥80 y.o. after 4 weeks, despite substantial contact reductions, indicating substantial transmission flows across ages. We derive the contribution of each age group to transmission. While shielding older individuals reduces mortality, it is insufficient to allow major relaxations of social distancing. When the epidemic remains manageable (R close to 1), targeting those most contributing to transmission is better than shielding at-risk individuals. Pandemic control requires an effort from all age groups.

Overwintering of Tranzchelia discolor in prune orchards in New South Wales

1987 ◽  
Vol 38 (5) ◽  
pp. 895 ◽  
Author(s):  
PJ Ellison ◽  
L McFadyen ◽  
PF Kable
Keyword(s):  
Leaf Litter ◽  
New South ◽  
New South Wales ◽  
Cross Infection ◽  
Infected Leaf ◽  
South Wales ◽  
One Year ◽  
Tranzschelia Discolor ◽  
Better Than

There are several ways in which Tranzschelia discolor may overwinter in prune orchards in the Murrumbidgee Irrigation Areas of New South Wales. The aecial state, cross-infection from peach and almond, twig cankers, and urediniospores on living leaves persisting through winter were considered, but were thought to be unlikely. The ability of urediniospores to survive on infected leaf litter, either on the ground under trees or lodged within the framework of trees, was studied over two winters. Urediniospore viability declined with time, but in both seasons a proportion were capable of germination in the spring. Spores exposed within the tree framework survived better than those exposed on the ground, with about 20% and less than 5% respectively remaining viable by spring. In both winters spores from litter which overwintered within the framework of the tree were able to infect prune leaves in the spring. The infectivity of spores exposed on the ground was tested in the spring of one year and infections resulted on inoculated plants. The implications of these findings for the control of the rust in prunes are discussed.

Synthesis of submicrometer-grained-ultrahigh-carbon steel containing 10% aluminum by ball-milling of powders

1996 ◽  
Vol 11 (11) ◽  
pp. 2725-2730 ◽  
Author(s):  
Eric M. Taleff ◽  
Mamoru Nagao ◽  
Yoshio Ashida ◽  
Oleg D. Sherby
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Bulk Material ◽  
Hot Isostatic Pressing ◽  
High Strength ◽  
Tensile Tests ◽  
Grain Sizes ◽  
Ultrahigh Carbon Steel ◽  
Processing Step ◽  
Size Powder

An ultrahigh-carbon (1.25 wt.%) steel alloy containing 10 wt.% aluminum (UHCS–10Al) was processed by a powder metallurgy technique. Gas-atomized powders were subjected to ball-milling in an attritor in order to obtain a submicrometer grain size. Powder material was consolidated by both hot isostatic pressing (HIP) and by hot isopressure extrusion (HIE). Bulk material with submicrometer grain sizes was produced from attrited powders. The chemical composition and microstructure of this material are characterized at each processing step, from atomization through consolidation. Tensile tests show that a high strength results from the submicrometer grain size produced in the bulk material.

scholarly journals Developing Deep Understanding and Literacy while Addressing a Gender-Based Literacy Gap

2010 ◽  
Vol 36 (1) ◽  
Author(s):  
Yanqing Sun ◽  
Jianwei Zhang ◽  
Marlene Scardamalia
Keyword(s):  
Conceptual Understanding ◽  
Classroom Discourse ◽  
Knowledge Building ◽  
Deep Understanding ◽  
Domain Specific ◽  
Literacy Gap ◽  
Grade Levels ◽  
Vocabulary Growth ◽  
Gender Based ◽  
Better Than

Online discourse from a class of 22 students (11 boys and 11 girls) was analysed to assess advances in conceptual understanding and literacy. The students worked over a two-year period (Grades 3-4), during which they contributed notes to an online Knowledge Building environment—Knowledge Forum®. Contributions revealed that both boys and girls produced a substantial amount of text and graphics, and that their written texts incorporated an increasing proportion of less-frequent, advanced words, including academic vocabulary and domain-specific words from grade levels higher than their own. Brief accounts of classroom discourse indicate how deep understanding and vocabulary growth mutually support each other in online and offline exchanges. The gender differences that were observed show boys doing slightly better than girls, suggesting that Knowledge Building has the potential to help boys overcome weaknesses in literacy.

scholarly journals Ocular trauma in patients presenting to Dhulikhel Hospital

2012 ◽  
Vol 9 (1) ◽  
pp. 54-57 ◽  
Author(s):  
P R Sthapit ◽  
S Marasini ◽  
U Khoju ◽  
G Thapa ◽  
B P Nepal
Keyword(s):  
Visual Acuity ◽  
Clinical Presentation ◽  
Ocular Trauma ◽  
Public Awareness ◽  
Prevalence Studies ◽  
Young Males ◽  
Common Location ◽  
One Year ◽  
Complete History ◽  
Better Than

Background Ocular trauma is an important cause of blindness and ocular morbidity throughout the world. Prevalence studies help to define the target group, plan strategies and thereby lessen trauma related blindness in the country. Objective To identify the risk factors for ocular trauma, those at risk, describe the visual acuity at time of clinical presentation, and assess the nature and severity of ocular trauma in patients presenting to Dhulikhel Hospital’s emergency department and eye OPD with ocular trauma. Methods It is a descriptive and prospective study of all the patients with ocular trauma presenting to Dhulikhel Hospital from December 2009 to December 2010. A complete history and detailed ophthalmologic evaluation was done and noted down. Results There were 112 subjects with ocular trauma. Mean age was 28.43±16.36 years with a range of one year to 74 years. Males predominated with 72.3% frequency (p<0.001). Incidence peaked in third decade of life (p<0.01). Ocular trauma peaked in months of September and October. Presenting visual acuity better than 6/12 was noted in 83.9% of cases whereas 2.7% of cases had visual acuity of <3/60. Household (56.3%, p<0.001) was the commonest place of injury with wooden objects (19.6%) being the commonest object of injury. Most of the injuries were mechanical (85.7%, p>0.001). ConclusionBlunt injuries were more common in young males. Household and workplace were common location of ocular injuries. Public awareness and strict legislation to use personal protective devices can help to reduce the occurrence of ocular injury.http://dx.doi.org/10.3126/kumj.v9i1.6264 Kathmandu Univ Med J 2011;9(1):54-7

Monoclonal antibodies used in solid-phase and liquid-phase assays, as exemplified by progesterone assay.

1987 ◽  
Vol 33 (8) ◽  
pp. 1331-1337 ◽  
Author(s):  
W Schramm ◽  
T Yang ◽  
A R Midgley
Keyword(s):  
Monoclonal Antibodies ◽  
Liquid Phase ◽  
Solid Phase ◽  
Protein A ◽  
High Specificity ◽  
Binding Properties ◽  
Affinity Constants ◽  
Hybridoma Cell Lines ◽  
One Year ◽  
Better Than

Abstract Two immunoglobulins secreted by hybridoma cell lines have been systematically investigated to determine if they could be used in solid-phase assays to give results comparable with those obtained by conventional liquid-phase radioimmunoassay (RIA). The antibodies, BQ.1 and BQ.2, bind with high specificity to the steroid hormone progesterone. The affinity constants, Ka, to 125I-labeled progesterone derivatives are 1.1 X 10(11) L/mol and 9.1 X 10(9) L/mol, respectively. Progesterone inhibited the binding of radioiodinated derivatives (amides of tyramine, histamine, and tyrosine methylester with 11 alpha-progesterone hemisuccinate) equally well. For solid-phase assays, we immobilized antibody BQ.1 via Protein A to different polystyrene surfaces (about 30 pg per tube at 50% inhibition of radiolabeled tracer). Under these conditions, the performance of this antibody for the quantification of progesterone was equivalent to that obtained in RIA. For the immobilized antibody BQ.2, only 1/10 of the amount used for optimal results in RIA was required in solid-phase assays. Binding of either antibody to the antigen was undiminished after several freezing-thawing cycles. When immobilized on solid matrices, both antibodies retained up to 95% of their binding properties for one year. Thus high-affinity, high-specificity monoclonal antibodies can be obtained for haptens and, when suitably immobilized, can be used in solid-phase assays with results equal to or better than those obtained with liquid RIA.

scholarly journals Clinical Transplantation of the Heart: A Review of 13 Years’ Personal Experience1

1981 ◽  
Vol 74 (9) ◽  
pp. 670-674 ◽  
Author(s):  
Christiaan N Barnard ◽  
D K C Cooper
Keyword(s):  
Heart Transplantation ◽  
Patient Survival ◽  
Pulmonary Complications ◽  
Circulatory Support ◽  
Heterotopic Transplantation ◽  
Human Donor ◽  
Clinical Transplantation ◽  
One Year ◽  
Transplantation Of The Heart ◽  
Better Than

The results of the heart transplantation operations performed personally by one surgeon (CNB) at Groote Schuur Hospital between 1967 and 1980 are reviewed. Of 9 orthotopic transplants performed between 1967 and 1973, 4 survived for more than one year and 2 remain alive today twelve and ten years later. Of 11 heterotopic transplants performed since 1974, one-year patient survival has been 82%, though one patient survived on his own heart after irreversible graft rejection. Three of the original 4 patients remain alive over five years later. These results are rather better than the overall results of our unit, where a total of 37 heterotopic transplants has been performed; the possible reasons for this are discussed. One patient, previously unreported, who underwent transplantation of the heart and both lungs in 1971, died after 23 days from pulmonary complications. Heterotopic transplantation using a xenograft (baboon or chimpanzee heart) has been performed on two occasions as a means of temporary circulatory support in patients with acutely failing hearts when no human donor was available. The chimpanzee heart supported the circulation satisfactorily for four days.

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