17 research outputs found
Fabrication and characterization of nanostructured porous silicon-silver composite layers by cyclic deposition: Dip-coating vs spin-coating
“This is the Accepted Manuscript version of an article accepted for publication in Nanotechnology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6528/ab96e5”Composites of nanostructured porous silicon and silver (nPSi-Ag) have attracted great attention due to the wide spectrum of applications in fields such as microelectronics, photonics, photocatalysis and bioengineering, Among the different methods for the fabrication of nanostructured composite materials, dip and spin-coating are simple, versatile, and cost-effective bottom-up technologies to provide functional coatings. In that sense, we aimed at fabricating nPSi-Ag composite layers. Using nPSi layers with pore diameter of 30 nm, two types of thin-film techniques were systematically compared: cyclic dip-coating (CDC) and cyclic spin-coating (CSC). CDC technique formed a mix of granular and flake-like structures of metallic Ag, and CSC method favored the synthesis of flake-like structures with Ag and Ag2O phases. Flakes obtained by CDC and CSC presented a width of 110 nm and 70 nm, respectively. Particles also showed a nanostructure surface with features around 25 nm. According to the results of EDX and RBS, integration of Ag into nPSi was better achieved using the CDC technique. SERS peaks related to chitosan adsorbed on Ag nanostructures were enhanced, especially in the nPSi-Ag composite layers fabricated by CSC compared to CDC, which was confirmed by FTDT simulations. These results show that CDC and CSC produce different nPSi-Ag composite layers for potential applications in bioengineering and photonicsThis work was financially supported by Fondo Nacional de Desarrollo Científico y Tecnológico FONDECYT–Chile (grant number 11180395), FONDEQUIP–Chile (project 160152
A connectome and analysis of the adult Drosophila central brain.
The neural circuits responsible for animal behavior remain largely unknown. We summarize new methods and present the circuitry of a large fraction of the brain of the fruit fly Drosophila melanogaster. Improved methods include new procedures to prepare, image, align, segment, find synapses in, and proofread such large data sets. We define cell types, refine computational compartments, and provide an exhaustive atlas of cell examples and types, many of them novel. We provide detailed circuits consisting of neurons and their chemical synapses for most of the central brain. We make the data public and simplify access, reducing the effort needed to answer circuit questions, and provide procedures linking the neurons defined by our analysis with genetic reagents. Biologically, we examine distributions of connection strengths, neural motifs on different scales, electrical consequences of compartmentalization, and evidence that maximizing packing density is an important criterion in the evolution of the fly's brain
The 13th Southern Hemisphere Conference on the Teaching and Learning of Undergraduate Mathematics and Statistics
Ngā mihi aroha ki ngā tangata katoa and warm greetings to you all. Welcome to Herenga
Delta 2021, the Thirteenth Southern Hemisphere Conference on the Teaching and Learning
of Undergraduate Mathematics and Statistics.
It has been ten years since the Volcanic Delta Conference in Rotorua, and we are excited to
have the Delta community return to Aotearoa New Zealand, if not in person, then by virtual
means. Although the limits imposed by the pandemic mean that most of this year’s 2021
participants are unable to set foot in Tāmaki Makaurau Auckland, this has certainly not
stopped interest in this event. Participants have been invited to draw on the concept of
herenga, in Te Reo Māori usually a mooring place where people from afar come to share
their knowledge and experiences. Although many of the participants are still some distance
away, the submissions that have been sent in will continue to stimulate discussion on
mathematics and statistics undergraduate education in the Delta tradition.
The conference invited papers, abstracts and posters, working within the initial themes of
Values and Variables. The range of submissions is diverse, and will provide participants with
many opportunities to engage, discuss, and network with colleagues across the Delta
community. The publications for this thirteenth Delta Conference include publications in the
International Journal of Mathematical Education in Science and Technology, iJMEST,
(available at https://www.tandfonline.com/journals/tmes20/collections/Herenga-Delta-2021),
the Conference Proceedings, and the Programme (which has created some interesting
challenges around time-zones), by the Local Organizing Committee. Papers in the iJMEST
issue and the Proceedings were peer reviewed by at least two reviewers per paper. Of the
ten submissions to the Proceedings, three were accepted.
We are pleased to now be at the business end of the conference and hope that this event will
carry on the special atmosphere of the many Deltas which have preceded this one. We hope
that you will enjoy this conference, the virtual and social experiences that accompany it, and
take the opportunity to contribute to further enhancing mathematics and statistics
undergraduate education.
Ngā manaakitanga,
Phil Kane (The University of Auckland | Waipapa Taumata Rau) on behalf of the Local
Organising Committ
Large expert-curated database for benchmarking document similarity detection in biomedical literature search
Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe
Green synthesis of silver nanoparticles by using leaf extracts from the endemic Buddleja globosa hope
Over the last few years, the green synthesis of nanoparticles (NPs) using plant extracts has emerged
as a promising methodology for the fabrication of metallic NPs (especially silver, copper, and gold
NPs), as it involves an easy, fast, low-cost, and environmentally friendly bioprocess. However, many
factors affect the sizes and morphologies of NPs biosynthesized by this method, including the
nature of the plant extract, among others. Therefore, the green synthesis of metal NPs with
defined stability, size, and morphology distribution remains under evaluation. In the present
study, we propose aqueous extracts from the endemic-medicinal plant Budleja globosa (“Matico”)
as an efficient bioproduct for the green synthesis of silver NPs (AgNPs). Experimental results
indicate that room temperature, low concentrations of leaf extracts of B. globosa, and silver
nitrate salt were sufficient to biosynthesize AgNPs with uniform size (16 nm) and shape
distribution (spherical).Fondo Nacional de Desarrollo Científico y Tecnológico 11150322
FONDECYT 3150101
DGIP Universidad Católica de Temuco 2015PF-GR-06
Bio-Nanomaterials Research Group VIP Universidad Católica de Temuco N°201GI-CI-01
project, DGIPUCT-CD-2010-01 project, and MECESUPUCT-0804 project
Use of nPSi-beta CD Composite Microparticles for the Controlled Release of Caffeic Acid and Pinocembrin, Two Main Polyphenolic Compounds Found in a Chilean Propolis
Propolis is widely recognized for its various therapeutic properties. These are attributed to its rich composition in polyphenols, which exhibit multiple biological properties (e.g., antioxidant, anti-inflammatory, anti-angiogenic). Despite its multiple benefits, oral administration of polyphenols results in low bioavailability at the action site. An alternative to face this problem is the use of biomaterials at nano-micro scale due to its high versatility as carriers and delivery systems of various drugs and biomolecules. The aim of this work is to determine if nPSi-beta CD microparticles are a suitable material for the load and controlled release of caffeic acid (CA) and pinocembrin (Pin), two of the main components of a Chilean propolis with anti-atherogenic and anti-angiogenic activity. Polyphenols and nPSi-beta CD microparticles cytocompatibility studies were carried out with human umbilical vein endothelial cells (HUVECs). Results from physicochemical characterization demonstrated nPSi-beta CD microparticles successfully retained and controlled release CA and Pin. Furthermore, nPSi-beta CD microparticles presented cytocompatibility with HUVECs culture at concentrations of 0.25 mg/mL. These results suggest that nPSi-beta CD microparticles could safely be used as an alternate oral delivery system to improve controlled release and bioavailability of CA or Pin-and eventually other polyphenols-thus enhancing its therapeutic effect for the treatment of different diseases
Use of nPSi-βCD Composite Microparticles for the Controlled Release of Caffeic Acid and Pinocembrin, Two Main Polyphenolic Compounds Found in a Chilean Propolis
Propolis is widely recognized for its various therapeutic properties. These are attributed to its rich composition in polyphenols, which exhibit multiple biological properties (e.g., antioxidant, anti-inflammatory, anti-angiogenic). Despite its multiple benefits, oral administration of polyphenols results in low bioavailability at the action site. An alternative to face this problem is the use of biomaterials at nano-micro scale due to its high versatility as carriers and delivery systems of various drugs and biomolecules. The aim of this work is to determine if nPSi-βCD microparticles are a suitable material for the load and controlled release of caffeic acid (CA) and pinocembrin (Pin), two of the main components of a Chilean propolis with anti-atherogenic and anti-angiogenic activity. Polyphenols and nPSi-βCD microparticles cytocompatibility studies were carried out with human umbilical vein endothelial cells (HUVECs). Results from physicochemical characterization demonstrated nPSi-βCD microparticles successfully retained and controlled release CA and Pin. Furthermore, nPSi-βCD microparticles presented cytocompatibility with HUVECs culture at concentrations of 0.25 mg/mL. These results suggest that nPSi-βCD microparticles could safely be used as an alternate oral delivery system to improve controlled release and bioavailability of CA or Pin—and eventually other polyphenols—thus enhancing its therapeutic effect for the treatment of different diseases
Nanoporous silicon microparticles embedded into oxidized hyaluronic acid/adipic acid dihydrazide hydrogel for enhanced controlled drug delivery
Oxidized hyaluronic acid cross-linked with adipic acid dihydrazide (oxi-HA/ADH) forms an injectable and biocompatible hydrogel suitable for treatment of musculoskeletal diseases and for drug delivery applications. In that sense, nanoporous silicon (nPSi) can be combined with biopolymers, such as oxi-HA/ADH hydrogel, to display new characteristics, which are not exhibited by the individual constituents alone. Under this context, in this work nPSi microparticles at concentrations from 0.1% to 1% m/v were embedded into oxi-HA/ADH hydrogel to improve its mechanical stability and enhance its control over drug release kinetics using Rose Bengal (RB) as a model drug because its cytotoxic effect in different cancer cell lines and tumors has been previously reported. Our results showed, for both compressive force and stress strength tests, that oxi-HA/ADH hydrogel with 1% nPSi microparticles doubled the values of control samples. Moreover, samples of oxi-HA/ADH with nPSi microparticles improved RB release kinetics control over pure oxi-HA/ADH hydrogel. Finally, the cell viability of nPSi microparticles embedded into oxi-HA/ADH hydrogel was confirmed using fibroblastsThis work was financially supported by FONDECYT–Chile (grant number 11180395), CONICYT PFCHA/DOCTORADO/2017-21172001 (Nelson Naveas) and CNPq 140924/2017-5 (Carla França). We thank Fig. 8. A) Cytotoxicity of nPSi microparticles. B) Cell viability of hydrogels. C.G. Franca ̧ et al. Microporous and Mesoporous Materials 310 (2021) 110634 11 Dr. Héctor Pesenti for providing the DRX facility (FONDEQUIP–Chile, project 160152), and Dr. Luis Sanhueza for optical measurements of UVVis spectroscop