Anchorage Sites Research Articles

Beyond the screw: Exploring the recurrence of oral lesions

The integration of skeletal anchorage systems has revolutionized orthodontics, especially with the advent of mini-screws known for their ease of use and minimal invasiveness. The mandibular buccal shelf area, with its ample high-quality bone and low failure rates, has become a preferred extra-alveolar anchorage site. However, complications involving adjacent soft tissues are common with orthodontic bone screw placement. This case report describes the recurrence of reactive oral lesions following placement of orthodontic bone screws in the buccal shelf area. During the course of orthodontic therapy, the patient developed exophytic growths twice, at the same site, on the lower right back buccal mucosa. Diode laser was used in both instances for excision of the lesion and the specimen was sent for histo-pathological analysis. The first lesion was diagnosed as inflammatory fibrous hyperplasia, while the recurrent lesion was identified as pyogenic granuloma. At 12-months follow-up, no new lesions were detected. This report highlights the influence of lesion development time on its clinical and histological presentation. It is postulated that leaving the bone screw in place after initial biopsy could have contributed to its recurrence. Complete excision is the preferred treatment. Treatment options, including laser therapy, are available for such lesions.

Theoretical Investigation of Propylene Epoxidation Using H2 and O2 Over Titanosilicate-Supported Au Catalysts

Titanosilicate-supported Au-cluster catalysts can be used to selectively synthesize propylene oxide from propylene using O2 and H2. However, the details of the catalytic reaction mechanism have not yet been elucidated. Thus, the reaction mechanism was investigated using density functional theory calculations. The calculation results revealed that active Ti-OOH forms on the surface Ti site, which is active as an oxidant and acts as an anchorage site for Au nanoclusters. The rate-determining step of propylene oxide synthesis on Au/titanosilicate is O insertion into propylene, with an activation energy of 1.37 eV. The propylene involved in this reaction is activated by adsorption on Au nanoclusters. Moreover, it was also found that the formation of Ti-OOH on Au/titanosilicate requires an activation energy of 0.48 eV, while it is barrierless on Au/anatase-TiO2. However, the decomposition energy of Ti-OOH on Au/titanosilicate is −0.16 eV, which is smaller than that on Au/anatase-TiO2 (−1.12 eV). The results indicate that Ti-OOH decomposes more readily on Au/titanosilicate than on Au/anatase-TiO2 but is easily regenerated because the reaction energy is significantly smaller than that on Au/anatase-TiO2. Therefore, these calculations are qualitatively in good agreement with the experimental results for Au/titanosilicate, which exhibited high catalytic activity at high temperatures.Graphical

Transposable elements as scaffold/matrix attachment regions: shaping organization and functions in genomes.

The hierarchical structure of eukaryotic genomes has regulatory layers, one of them being epigenetic "indexing" of the genome that leads to cell-type-specific patterns of gene expression. By establishing loops and defining chromatin domains, cells can achieve coordinated control over multi-locus segments of the genome. This is thought to be achieved using scaffold/matrix attachment regions (S/MARs) that establish structural and functional loops and topologically associating domains (TADs) that define a self-interacting region of the genome. Large-scale genome-wide mapping of S/MARs has begun to uncover these aspects of genome organization. A recent genome-wide study showed the association of transposable elements (TEs) with a significant fraction of S/MARs, suggesting that the multitude of TE-derived repeats constitute a class of anchorage sites of chromatin loops to nuclear architecture. In this study, we provide an insight that TE-driven dispersal of S/MARs has the potential to restructure the chromosomes by creating novel loops and domains. The combination of TEs and S/MARs, as elements that can hop through the genome along with regulatory capabilities, may provide an active mechanism of genome evolution leading to the emergence of novel features in biological systems. The significance is that a genome-wide study mapping developmental S/MARs reveals an intriguing link between these elements and TEs. This article highlights the potential of the TE-S/MAR combination to drive evolution by restructuring and shaping the genome.

3D Filaments Based on Polyhydroxy Butyrate-Micronized Bacterial Cellulose for Tissue Engineering Applications.

In this work, scaffolds based on poly(hydroxybutyrate) (PHB) and micronized bacterial cellulose (BC) were produced through 3D printing. Filaments for the printing were obtained by varying the percentage of micronized BC (0.25, 0.50, 1.00, and 2.00%) inserted in relation to the PHB matrix. Despite the varying concentrations of BC, the biocomposite filaments predominantly contained PHB functional groups, as Fourier transform infrared spectroscopy (FTIR) demonstrated. Thermogravimetric analyses (i.e., TG and DTG) of the filaments showed that the peak temperature (Tpeak) of PHB degradation decreased as the concentration of BC increased, with the lowest being 248 °C, referring to the biocomposite filament PHB/2.0% BC, which has the highest concentration of BC. Although there was a variation in the thermal behavior of the filaments, it was not significant enough to make printing impossible, considering that the PHB melting temperature was 170 °C. Biological assays indicated the non-cytotoxicity of scaffolds and the provision of cell anchorage sites. The results obtained in this research open up new paths for the application of this innovation in tissue engineering.

One-pot synthesis of injectable self-healing thermoresponsive halloysite nanotube-reinforced nanocomposite hydrogels for tissue engineering

Injectable hydrogels that can fill irregular defects through a minimally invasive approach are of particular interest to replace invasive surgeries in tissue scaffold implantation. However, the use of injectable hydrogels is often restricted by the drawback of having poor mechanical properties. In this work, a novel halloysite nanotube (Hal)-based hydrogel was developed using bacterial cellulose and gelatin, as well as acid-treated Hal to serve a dual purpose of providing structural support for tissue regeneration while offering possibilities for drug delivery at a local site. The fabricated hydrogels were then analyzed physically and morphologically for injectability, gelling ability, self-healing capability, as well as composition characterization, surface morphology, mechanical performance, and biodegradability. Analyses revealed that all the hydrogels could be injected as a liquid, with an in-situ sol-gel transition occurring after 10 min at 37 °C. Furthermore, the honeycomb-like structure of the hydrogel and the rougher surface where Hal dispersed over the surfaces could also provide sufficient space and anchorage sites to facilitate cell attachment. With the moisture content reaching up to 85–92%, the hydrogels could provide a moist recovery environment for the healing process. More importantly, the incorporation of Hal greatly improved the compressive strength and Young's modulus up to 60% and 40%, respectively. Furthermore, antibiotic-loaded hydrogels demonstrated effective antimicrobial activity against Staphylococcus epidermidis, methicillin-susceptible Staphylococcus aureus (MSSA), and methicillin-resistant S. aureus (MRSA). Collectively, such hydrogels with a minimally invasive delivery approach and the potential to aid in tissue regeneration can be applied in biomedical and tissue engineering applications, along with a combined local delivery of antimicrobial agents in the near future.

Safe sites for buccal shelf bone screw placement in various skeletal malocclusions: A CBCT study.

The mandibular buccal shelf area is an extra-alveolar anchorage site that has high quality and quantity of bone, provides biomechanical benefits and has low failure rates. It is essential to place the implant in the region of bone with optimal thickness. The aim of this study was to determine the suitable site of the mandibular buccal shelf for bone screw insertion at 90 degrees and 30 degrees angles of insertion and various heights, angulations, areas of the buccal shelf in prognathic and retrognathic mandibles, and vertical and horizontal growth patterns. In this retrospective study, we evaluated the cone-beam computed tomography (CBCT) images of 48 patients in the age range of 18-30 years, divided into four groups. Seven sectional sites were examined at 3, 5, and 7 mm from the alveolar crest at 90 degrees and 30 degrees. The angulation and area of the buccal shelf were examined. Cortical bone thickness increased distally from the first to the second molar in all four groups. The preferred site for buccal shelf implant placement was distal to the mandibular second molar. The maximum amount of cortical bone was observed distal to the second molar, 7 mm vertically from the alveolar crest, when the buccal shelf implant was placed at 30 degrees angulation to the long axis of the tooth.

Initial Recognition and Attachment of the Zika Virus to Host Cells: A Molecular Dynamics and Quantum Interaction Approach.

The zika virus (ZIKV), transmitted to humans from the bites of Aedes Aegypti and Aedes Albopictus mosquitoes produces Zika fever and neurodegenerative disorders that despite affecting millions of people, most recently in Africa and the Americas, has been declared a neglected tropical disease by the World Health Organization. In this work, atomistic molecular dynamics simulations followed by rigorous analysis of the intermolecular interactions reveal crucial aspects of the initial virus⋯cell molecular recognition and attachment, events that trigger the infectious cycle. Previous experimental studies have shown that Dermatan Sulfate (DS) and Chondroitin Sulfate A (CSA), two glycosaminoglycans which are actually epimers to each other and that are structural constituents of receptors expressed in cell membranes, are the preferred anchorage sites, with a marked preference for DS. Our calculations rationalize this preference from a molecular perspective as follows: when free of the virus, DS has one sulfate group that does not participate in intramolecular strong hydrogen bonds, thus, it is readily available to interact with the envelope protein of the virus (Zika-E), then, after formation of the complexes, Zika-E⋯DS exhibits ten strong salt brides connecting the two fragments against only six salt bridges and two hydrogen bonds in Zika-E⋯CSA. Our results complement the current view of the interaction between the virus and the receptor glycosoaminoglycans revealing that the negatively charged carboxylate groups in CSA and DS are just as important as the sulfates because of the formation of equally strong salt bridges with the positively charged Arginine and Lysine aminoacids in the envelope protein of the virus.

131I-C19 Iodide Radioisotope and Synthetic I-C19 Compounds as K-Ras4B-PDE6δ Inhibitors: A Novel Approach against Colorectal Cancer-Biological Characterization, Biokinetics and Dosimetry.

In 40–50% of colorectal cancer (CRC) cases, K-Ras gene mutations occur, which induce the expression of the K-Ras4B oncogenic isoform. K-Ras4B is transported by phosphodiesterase-6δ (PDE6δ) to the plasma membrane, where the K-Ras4B–PDE6δ complex dissociates and K-Ras4B, coupled to the plasma membrane, activates signaling pathways that favor cancer aggressiveness. Thus, the inhibition of the K-Ras4B–PDE6δ dissociation using specific small molecules could be a new strategy for the treatment of patients with CRC. This research aimed to perform a preclinical proof-of-concept and a therapeutic potential evaluation of the synthetic I-C19 and 131I-C19 compounds as inhibitors of the K-Ras4B–PDE6δ dissociation. Molecular docking and molecular dynamics simulations were performed to estimate the binding affinity and the anchorage sites of I-C19 in K-Ras4B–PDE6δ. K-Ras4B signaling pathways were assessed in HCT116, LoVo and SW620 colorectal cancer cells after I-C19 treatment. Two murine colorectal cancer models were used to evaluate the I-C19 therapeutic effect. The in vivo biokinetic profiles of I-C19 and 131I-C19 and the tumor radiation dose were also estimated. The K-Ras4B–PDE6δ stabilizer, 131I-C19, was highly selective and demonstrated a cytotoxic effect ten times greater than unlabeled I-C19. I-C19 prevented K-Ras4B activation and decreased its dependent signaling pathways. The in vivo administration of I-C19 (30 mg/kg) greatly reduced tumor growth in colorectal cancer. The biokinetic profile showed renal and hepatobiliary elimination, and the highest radiation absorbed dose was delivered to the tumor (52 Gy/74 MBq). The data support the idea that 131I-C19 is a novel K-Ras4B/PDE6δ stabilizer with two functionalities: as a K-Ras4B signaling inhibitor and as a compound with radiotherapeutic activity against colorectal tumors.

Dynamics of Maritime Trade along the Fako Coastal Belt of Cameroon: Ambiance, Challenges and Sustainable Combat Strategies

Maritime trade is dynamic and indispensable for economic growth and development around the World. This trade if not well monitored can become a threat to development considering the illicit and criminal transactions that surrounds the sector. In Cameroon, this informal trade has degraded customs income and promoted the infiltration of contraband goods into the country via local anchorage sites where custom services are weak. This trade has affected the State pricing policy of certain goods especially fuel. It is against this background that this study sets out to investigate, seaborne trade, and the illegal transactions that are common along the Fako coastal belt of Cameroon. Data for the study have been gathered from secondary and primary sources. Secondary data were gleaned from soft and hard copies of both published and unpublished documents, newspapers, and decrees relevant to maritime transport and trade. Primary data were sourced from field surveys where a simple random sampling technique was used to administer 278 copies of questionnaires to 10 localities along the Fako coastal belt of Cameroon using a convenient sample size. Supplementary primary data was gotten via interviews and observations in the three seaports along the coast. Results revealed that the Limbe, Tiko and Idenau ports though secondary, handles thousands of tonnes of cargo annually making Fako Division where they are located in Cameroon an eminent trading hub. Statistics from the Limbe Port Authority (PAL) indicated an increasing trend of export and imports annually in thousands of tonnes. The results shows that illicit seaborne trade is very common along this coastal belt with over 67 percent of the goods coming in from neighbouring Nigeria. The illicit product identified are petroleum products (46.2%), pharmaceutical products (30 %), food items (16.7%) and chemical fertilizers and others (5.3% and 3.8%) respectively. The results also revealed that in the year 2021 between January and August, over 18 cases of illicit goods were intercepted along this coastline with petroleum products destined to Limbe, Tiko and Idenau ports dominating. The reasons for the persistency of this illicit trade were corruption and the existence of a network of illegal organisation that transact the goods. This study recommends that custom and naval services be reinforced along this coastal belt to ascertain the type and originality of the products entering the country via the sea. Also, the State should investigate and dismantle illicit and organised illegal seaborne trade chains and charge officials at the maritime frontiers to be responsible and corruption free.

Niobium- and titanium-based coating for the protection of carbon steel SAE 1020 against corrosion

PurposeThe purpose of this paper is to evaluate the protection against corrosion of carbon steel SAE 1020 promoted by a niobium- and titanium-based coating produced from a resin obtained by the Pechini method.Design/methodology/approachA resin was prepared with ammonium niobium oxalate as niobium precursor and K2TiF6 as titanium precursor. Carbon Steel SAE 1020 plates were dip coated in the resin and calcinated for 1 h at 600 ºC. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used to characterize the coating morphologically and structurally. Open circuit potential, electrochemical impedance spectroscopy, anodic potentiodynamic polarization and scanning vibrating electrode technique were used to evaluate the corrosion protection of the coating.FindingsThe electrochemical analyses evidence slight protection against corrosion of the coating by itself; however, the needle-like crystal structure obtained may potentially provide a good anchorage site, suggesting the coating could be used as a pretreatment that may present similar application to phosphating processes, generating lower environmental impacts.Originality/valueDue to increasingly restrictive environmental laws, new environmentally friendlier surface treatments must be researched. This paper approaches this matter using a combination of niobium- and titanium-based coating, produced by a cleaner process, the Pechini method.

Therapeutic Effects of Removable İntraoral Class III Appliances on Dentofacial Structures: A Comprehensive Literature Review

The aim of this comprehensive review was to shed light on removable intraoral Class III appliances and their dentoskeletal effects in growing Class III subjects. Recently, intraoral Class III appliances have been recommended in cases of Class III malocclusions arising from maxillary retrusion instead of the Facemask appliance, which is commonly used in children at development age, due to its disadvantages including large volume and non-esthetic design, lack of cooperation, and its contribution to the irritation in the anchorage site. For these reasons, the appliances used in the treatment of Class II malocclusions have been modified for the treatment of Class III malocclusions. Among these, Fränkel Appliance III, which was introduced by Rolf Fränkel, is the most well-known modified appliance and the other well-known examples include Bionator III, Reverse Twin Block, and Magnetic Appliance III. Additionally, the other removable intraoral appliances introduced in the literature include Modified Tandem and Double-plate Appliance. The present review examined the designs of these appliances reported in the literature as well as their skeletal and dentoalveolar effects on the maxilla and mandible.

Geotechnical Characteristic Assessments of Floodplain Soils Using SCPTU Data in Nanjing, China

In order to improve the understanding of such floodplain sediments and determining the validity of the tests, an extensive series of multifunctional seismic piezocone tests with pore pressure dissipation phase have been performed and supplemented with conventional borings, standard penetration, laboratory testing, and so forth. Sounding results from SCPTU were used to determine the stratigraphic profiles and the soil characteristics of two anchorage sites. A comparison of the boring and laboratory results with the CPTU profiles showed that the CPTU provided excellent information on soil stratigraphy and good guidance for determination of behavior and engineering implications of recent Yangtze River floodplain. At an area where local correlations based on modern SCPTU do not exist, methods for estimating coefficient of earth pressure at rest (K0), hydraulic permeability (kh), and equivalent stiffness (G0) associated with bridge foundation design are presented, compared, and verified. Results also illustrate the complexity and variability of the floodplain stratigraphy and soil properties, which means that the suggestions in this study should be updated when more local experience is obtained. This case study suggests that such enhanced seismic piezocone test should be considered as a potential tool and the instrument of first choice in site characterization programs for design of bridges founded on complicated soils in China.

En-masse Distalisation of Mandibular Dentition with Ramal Miniplate for Correction of Class III Malocclusion: A Case Report

Mandibular arch distalisation is a non extraction camouflage treatment modality for class III malocclusion, and the introduction of skeletal anchorage devices has enabled its use with minimal patient compliance and reciprocal side effects. The aim of this case report was to show the efficacy of the retromolar fossa as a suitable skeletal anchorage site for mandibular dentition distalisation. Inter-radicular miniscrews are the most commonly used forms of skeletal anchorage; however, they are often problematic in the mandible because of their high failure rate in the posterior region. In order to avoid these issues, some clinicians place miniscrews extraradicularly in the buccal shelf area or in the retromolar area. This approach is demonstrated through a case report of an 18- years-old male patient with a chief complaint of extra teeth and spacing in the upper front teeth. The diagnosis formulated was a Class III skeletal pattern, anterior divergence, Angle’s Class III malocclusion with an edge-to-edge bite and presence of mesiodens in the premaxillary region. The treatment approach was to use skeletal anchorage to distalize the mandibular arch with ramal plates after extraction of the mandibular third molars, since the patient refused the surgical treatment. At the 1 year follow-up appointment, there was no noticeable relapse or signs or symptoms of adverse effects like gingival recession, mobility and bone loss.

Palaeoshoreline reconstruction and underwater archaeological potential of Liman Tepe: A long-occupied coastal prehistoric settlement in western Anatolia, Turkey

Rising post-glacial sea levels had a major influence on the prehistoric settlement of the Aegean coastal zone. At Liman Tepe, an important Chalcolithic-Bronze Age coastal settlement on the south coast of the Bay of Izmir, archaeological evidence suggests a Neolithic (ca. 9600-5500 BCE) presence, but no settlement has been discovered on land. Sea levels during the Neolithic period were between 6 and >20 m below present and there is high potential for discovery of submerged prehistoric sites. Marine sediment coring and geophysical investigations (bathymetry, sub-bottom seismic profiling; >600 line-km) were conducted over a 4-km2 inshore area to assess the underwater archaeological potential. Multi-proxy sediment analysis (sedimentary facies, micropalaeontology, micro-XRF geochemistry) was conducted on 20 cores to reconstruct the relative sea level (RSL) history and coastal palaeogeography. Palaeoshoreline positions were estimated by back-stripping of the decompacted sediment thickness from a digital bathymetric model (DBM).The DBM reveals a drowned middle Holocene coastal plain with well-preserved relict river channels, palaeoshorelines and coastal headlands. The inshore stratigraphy consists of shoreface, foreshore and lagoonal deposits overlying terrestrial clay and palaeosols, defining a marine transgressive surface (MTS). The MTS records the inundation of the coastal plain prior to ca. 4000 BCE (transgressive systems tract; TST) and is marked in cores by an increasing abundance of foraminifera and a rise in Ca/Ti. During the Early Neolithic (ca. 6700 BCE), the shoreline was >500 m seaward (RSL ∼ −14 to −16 m) and Karantina Island was a broad coastal headland with a sheltered western embayment. By the Middle Chalcolithic (ca. 4800 BCE), the coastline had transgressed ∼800 m inland of the present shoreline and the Liman Tepe headland was separated from the mainland by a shallow coastal wetland. The maximum transgression (∼1 km inland at ca. 4000 BCE) was followed by a shift to a high-stand systems tract (HST) and rapid coastline progradation by barrier accretion and lagoon development. Palaeogeographic maps identify areas with high underwater archaeological potential: 1) palaeoriver channels and lowland riverine habitats formed during the TST, prior to 4000 BCE, 2) submerged palaeoshorelines and coastal promontories (water depths 10–14 mbsl) with high potential for Neolithic sites, and 3) protected coastal embayments and lagoons representing possible prehistoric anchorage sites.

Oxidized cellulose nanocrystal as sustainable crosslinker to fabricate carboxylated nitrile rubber composites with antibiosis, wearing and irradiation aging resistance

Oxidized cellulose nanocrystal (OCNC) prepared by H 2 O 2 served as anchorage sites of combined Zn 2+ -carboxylate bonds and curing agent precursor for fabricating XNBR/OCNC/ZnO composite via in situ interfacial reactions. The novel cross-linking by OCNC influenced on the microstructure, morphology, and properties of the composites were characterized. The cross-linking of Zn 2+ -carboxylate networks endow the composites to achieve 295% and 200% increases in tensile strength and cross-linking density, excellent wear resistance (90% reduction in relative mass loss compared to neat XNBR), irradiation aging resistance, respectively. This study provides a universal, simple and scalable method for the fabrication of multifunctional rubber composites by constructing Zn 2+ -carboxylate cross-linked network with natural cellulose resources .

French Hip & Knee Society classification of short-stem hip prostheses: Inter- and intra-observer reproducibility

IntroductionIn total hip replacement (THR), a short stem theoretically provides more physiological force transfer to the proximal femur, conserves bone stock and facilitates minimally invasive surgery. On the other hand, such implants involve a learning curve and incur risk of malpositioning or fracture and of secondary mobilization. There are several types of short stem, and classification is needed. Classifications exist, but are based more on implant length than on anchorage zone, and most have not been tested for reproducibility. The French Hip & Knee Society (SFHG) developed a short-stem classification based on anchorage zone inside the femur. The objectives of the present study were: (1) to present the classification, (2) to apply it to the short-stem models available in France and those widely used worldwide, and (3) to assess reproducibility. HypothesisThe SFHG short-stem classification enables reproducible comparison. Material and methodA short-stem classification according to anchorage zone was drawn up by an expert group. The stems and the classification were presented to 12 surgeons performing THR, who classified the stems according to the classification; a retest was performed 2 months later. ResultsThe classification is based on femoral stem anchorage site, in 5 types: type 1, cephalic; type 2, isolated cervical; type 3, Calcar femorale; type 4, metaphyseal; and type 5, conventional metaphyseal-diaphyseal, with shortened stems. Inter-observer reproducibility was 92.7% [95%CI: 91.7%–93.6%], with kappa 0.785 [95%CI: 0.755–0.814], and Lin test-rest concordance correlation coefficient 0.852 [95%CI: 0.836–0.869]. Intra-observer reproducibility was 94.0% [95%CI: 91.9%–96.1%], with kappa 0.820 [95%CI: 0.759–0.882], and Lin test-retest concordance correlation coefficient 0.820 [95%CI: 0.792–0.849]. DiscussionThis new classification enables femoral implants to be reproducibly compared according to anchorage zone. Level of evidenceIV; retrospective study without control group.

Using a multi-proxy approach to locate the elusive Phoenician/Persian anchorage of Tel Akko (Israel)

Previous geoarchaeological research on the Akko coastal plain have contributed to the understanding of the ancient coastal interface and added evidence as to the location/shift of the ancient anchorages dating from the Middle Bronze Age (beginning of the 2nd Millennium BC) to the Early Hellenistic period (mid of the 2nd century BC) of the ancient site of Tel Akko. The present research provides new insights into the environmental changes and likely anchorage sites along the western edge of Tel Akko in the 1st Millennium BC (Iron Age II and III, periods associated with the Phoenician mariners and Persian army incursion). Our approach for locating the anchorage is based on a detailed investigation of subsurface sediments combining sedimentological and faunal analysis and radiocarbon dating of cores as well as identification of ceramic sherds found in the cores, and ground penetrating radar (GPR) and electrical resistivity tomography (ERT) surveys. Paleoenvironmental changes are compared and contrasted with the results of the archaeological investigations on the tell and in its vicinity. Our new data demonstrates that the Phoenician/Persian maritime interface of Tel Akko was mainly oriented toward the southwestern area of the tell where a natural anchorage was likely to have been located. At that time, the water depth in this area was ca. 2m, allowing for the anchorage of seagoing vessels. Increasing sediment deposition lead to the deterioration of direct, and eventual loss of access, to the sea. These conditions initiated the abandonment of the tell in the Early Hellenistic period as well as the westward shift to habitation on the peninsula, now the ‘Old city of Akko’, the Crusaders' Saint Jean d’Acre.

Thiolate chitosan nanoparticles capable to delivery nitric oxide: synthesis, characterization and antibacterial potential

Nitric oxide (NO) is a small but powerful molecule. It is involved in several biological pathways such as vasodilation, wound healing and toxicity towards pathogens. At high concentrations, NO has a toxicity towards bacteria, virus and fungi which has a great biomedical potential. However, NO has a small half-life of just a few seconds and this hazards its clinical application. In this scenario, the combination of nanotechnology with NO donors can create new strategies to load and deliver NO. Polymeric nanomaterial intrinsically have advantages such as low toxicity, biodegradability and low-cost. In this study, we used chemically modified chitosan (CS) to prepare nanoparticles capable of loading and releasing NO with antibacterial activity. CS was chemically modified to add a thiol group (-SH) to its structure. This modification was performed by the reaction with thioglycolic acid (TGA) in the presence of a carbodiimide (EDC). The thiol groups in CS structure serve a double function: create an anchorage site for NO and increase polymer mucoadesivity. The synthesis of thiolated chitosan nanoparticles (TCS NP) occurred by ionotropic gelation method using sodium tripolyphosphate (TPP) as counter ion. The NO donor precursor molecule, mercaptosuccinic acid (MSA), was encapsulated into TCS NP to increase loading capacity of NO. To identify the best paraments of the synthesis we used the ratios 1:3, 1:4, 1:5, 1:6 and 1:7 for TCS:TPP. TCS NPs were characterized by dynamic light scattering (DLS), microscopy electron transmission (MET) and nanoparticle tracking analysis (NTA). The release of NO was characterized by a kinetic using Uv-vis spectroscopy. Finally, the antibacterial potential was evaluated by minimum inhibitory concentration (MIC) assay against Staphylococcus aureus, Streptococcus mutans and Escherichia coli strains. The ratio 1:5 showed the most adequate size parameters and the other analysis were performed using it. The hydrodynamic size was found to be 113.0 ± 1.6 nm, PDI of 0.292 ± 0.035 and zeta potential of 27.1 ± 0.9. The MET images indicated small and spherical nanoparticles. The kinetic profiles showed a linear release of NO reaching the 100% after 150 min. The antibacterial effect was tested for E. coli, S. aureus and S. mutans. The MIC values was 50 µg mL for NO-CS NP, this result was 50% lower compared to TCS NPs for S. mutans and E. coli. The TCS NP has suitable properties for the biomedical field with potential for antibacterial application.

Structure and Location of Protein Sites Binding Self-Associated Congo Red Molecules with Intercalated Drugs as Compact Ligands-Theoretical Studies.

In the search for new carriers capable of transporting toxic drugs to a target, particular attention has been devoted to supramolecular systems with a ribbon-like micellar structure of which Congo red is an example. A special promise of the possible use of such systems for directing drugs to a target emerges from their particular affinity to immune complexes and as an independent property, binding many organic compounds including drugs by intercalation. Serum albumin also appeared able to bind micellar particles of such systems. It may protect them against dilution in transport. The mathematical tool, which relies on analysis of the distribution of polarity and hydrophobicity in protein molecules (fuzzy oil drop model), has been used to find the location of binding area in albumin as well as anchorage site for Congo red in heated IgG light chain used as a model presenting immunoglobulin-like structures. Results confirm the suggested formerly binding site of Congo red in V domain of IgG light chain and indicated the cleft between pseudo-symmetric domains of albumin as the area of attachment for the dye.

A Demand-Supply Matching-Based Approach for Mapping Renewable Resources Towards 100% Renewable Grids in 2050

Recently, many renewable energy (RE) initiatives around the world are based on general frameworks that accommodate the regional assessment taking into account the mismatch of supply and demand with pre-set goals to reduce energy costs and harmful emissions. Hence, relying entirely on individual assessment and RE deployment scenarios may not be effective. Instead, developing a multi-faceted RE assessment framework is vital to achieving these goals. In this study, a regional RE assessment approach is presented taking into account the mismatch of supply and demand with an emphasis on Photovoltaic (PV) and wind turbine systems. The study incorporates mapping of renewable resources optimized capacities for different configurations of PV and wind systems for multiple sites via test case. This approach not only optimizes system size but also provides the appropriate size at which the maximum renewable energy fraction in the regional power generation mix is maximized while reducing energy costs using MATLAB’s ParetoSearch algorithm. The performance of the proposed approach is tested in a realistic test site, and the results demonstrate the potential for maximizing the RE share compared to the achievable previously reported fractions. The results indicate the importance of resource mapping based on energy-demand matching rather than a quantitative assessment of anchorage sites. In the examined case study, the new assessment approach led to the identification of the best location for installing a hybrid PV / wind system with a storage system capable of achieving a nearly 100% autonomous RE system with Levelized cost of electricity of 0.05 USD/kWh.