Adaptive formation control for obstacle avoidance of USVs with asymmetric input saturation.

Due to the complex maritime navigation environment, Unmanned Surface Vessels (USVs) are influenced by unknown nonlinear dynamics arising from external disturbances and internal uncertainties. Achieving effective formation control while maintaining obstacle avoidance performance presents significant challenges. This article proposes a Neural Networks (NNs) adaptive formation Artificial Potential Field (APF) obstacle avoidance control method for multiple USVs. By employing online updates of Radial Basis Function (RBF) NNs technology, the unknown nonlinear dynamics are approximated, thus addressing complex nonlinear dynamics problems. In scenarios involving multiple USVs navigating under high wind and wave conditions, collisions with obstacles frequently occur. To tackle this issue, a leader-follower control strategy is designed that effectively addresses risk assessment and obstacle avoidance under such challenging conditions. Additionally, to account for saturation constraints or potential faults in the controller inputs commonly encountered in engineering applications, it implements an asymmetric auxiliary control system. Furthermore, the Lyapunov stability theorem is utilized to ensure the stability of both the formation control and obstacle avoidance algorithms for multiple USVs. Finally, the effectiveness of the proposed algorithm is validated through simulations.

The Surface Deterioration of Prefabricated Zirconia Crowns on Exposure to Acidulated Phosphate Fluoride Gel: An In Vitro Study.

Introduction Zirconia is a widely used restorative material in dentistry due to its superior aesthetic and mechanical properties. The oral cavity is a complex ecosystem with various components, which affect the teeth, as well as artificial restorative materials. Various personal and professional interventions carried out can severely affect the properties of restorative materials, thus altering the longevity of the prosthesis; 1.23% acidulated phosphate fluoride (APF) gel is one such professionally applied topical fluoride agent used to prevent caries. The interaction of this APF gel with highly aesthetic restorative material such as zirconia crowns is unknown. Objective The objective of this study is the evaluation of the surface deterioration of prefabricated zirconia crowns on exposure to deionised water and 1.23% acidulated phosphate fluoride (APF) gel with field emission scanning electron microscope (FE-SEM) and mass loss analysis. Material and method Sixty prefabricated paediatric zirconia crowns were taken, 10 samples were immersed in deionised water, 40 samples were immersed in 1.23% APF gel and 10 samples were used as control. Surface morphology and mass loss analysis were carried out at time intervals of four minutes, 24 hours, 48 hours and 72 hours using FE-SEM and digital weighing machine. Results No visual change was observed in the samples immersed in deionised water at the time interval of 72 hours. There was a marked visual change in samples immersed in 1.23% APF gel at the time interval of four minutes to 72 hours; this change involved a loss of gloss to the appearance of chalkiness. FE-SEM analysis for the control group and samples immersed in deionised water showed a smooth, continuous, undisrupted top layer, while samples immersed in 1.23% APF gel showed changes ranging from surface etching, to pinhole porosities, to crack formation and disruption of the surface depending upon the exposure time. Conclusions On the immersion of zirconia crowns in an aqueous acidic medium of 1.23% APF gel, the crowns showed flaws, imperfections and uneven superficial layers. It has been observed that surface grains are disrupted and micropores have been formed. This degraded superficial surface when undergoes cyclic mechanical loading can accelerate the ageing phenomenon of zirconia. Mechanical forces along with a dynamic electrochemical environment can degrade the material properties of zirconia.

Dynamic 3D Point-Cloud-Driven Autonomous Hierarchical Path Planning for Quadruped Robots.

Aiming at effectively generating safe and reliable motion paths for quadruped robots, a hierarchical path planning approach driven by dynamic 3D point clouds is proposed in this article. The developed path planning model is essentially constituted of two layers: a global path planning layer, and a local path planning layer. At the global path planning layer, a new method is proposed for calculating the terrain potential field based on point cloud height segmentation. Variable step size is employed to improve the path smoothness. At the local path planning layer, a real-time prediction method for potential collision areas and a strategy for temporary target point selection are developed. Quadruped robot experiments were carried out in an outdoor complex environment. The experimental results verified that, for global path planning, the smoothness of the path is improved and the complexity of the passing ground is reduced. The effective step size is increased by a maximum of 13.4 times, and the number of iterations is decreased by up to 1/6, compared with the traditional fixed step size planning algorithm. For local path planning, the path length is shortened by 20%, and more efficient dynamic obstacle avoidance and more stable velocity planning are achieved by using the improved dynamic window approach (DWA).

A Comparison of the Fluoride 'Paint- On' vs Tray Application Techniques for Enamel Remineralisation.

BACKGROUND: Fluoride gel treatment is not recommended for children < 6 years old due to its potential toxicity. Hence the aim of this study was to compare the effect of 1.23% acidulated-phosphate fluoride (APF) gel paint-on and the conventional tray application techniques on artificial, deciduous enamel carious lesions embedded on wearable appliances. METHODS: In a randomised crossover study, the volunteer children (n = 29) wore mandibular removable appliances containing embedded tooth specimens with artificial carious lesions. The volunteers had 3 different treatment protocols: (I) 0.4 mL non-fluoride (control) gel, (II) 0.4 mL paint-on 1.23% APF gel or (III) 5 mL 1.23% APF gel, 4 minutes tray application. After 1 hour, the appliances were removed and the specimens underwent an in vitro, 14 days of pH-cycling. The mean percentage reduction in fluorescence (ΔF, %) at baseline (ΔF0) and after the pH-cycling (ΔF1) were determined using quantitative light-induced fluorescence-digital analysis. The mean ΔΔF (ΔF1-ΔF0) was calculated to compare the differences between groups. RESULTS: The mean ΔΔF of groups I to III were -1.42 ± 1.49, 1.06 ± 2.11, and 1.12 ± 3.57 and -1.25 ± 1.44, 1.13 ± 1.84 and 1.44 ± 3.62 for the smooth surface and proximal surface lesions, respectively. The mean ΔΔF in the 2 treatment groups were significantly greater compared with the control group (P < .001). There was no significant difference in ΔΔF between the APF gel tray and paint-on groups either in the smooth surfaces, or the proximal surfaces (P = .629 and P = .613, respectively). CONCLUSION: Our study, for the first time, indicates that the paint-on application of APF gel or the tray application of APF had a similar enamel remineralisation effect. Clinically, this implies that, particularly in younger children, the paint-on application of fluoride is less cumbersome, and possibly more tolerable with a lesser likelihood of fluoride ingestion than the tray application technique. TRIAL REGISTRATION: Thai Clinical Trial Registry (https://www.thaiclinicaltrials.org/show/TCTR20190724001).

Predictive Value of the Mayo Adhesive Probability (MAP) Score in Laparoscopic Partial Nephrectomies: A Systematic Review from the EAU Section of Uro-Technology (ESUT).

The Mayo Adhesive Probability (MAP) score is a radiographic scoring system that predicts the presence of adherent perinephric fat (APF) during partial nephrectomies (PNs). The purpose of this systematic review is to summarize the current literature on the application of the MAP score for predicting intraoperative difficulties related to APF and complications in laparoscopic PNs. Three databases, PubMed, Scopus and Cochrane, were screened, from inception to 29 October 2023, taking into consideration the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Guidelines. All the inclusion criteria were met by eight studies. The total operative time was around two hours in most studies, while the warm ischemia time was <30 min in all studies and <20 min in four studies. Positive surgical margins, conversion and transfusion rates ranged from 0% to 6.3%, from 0% to 5.0% and from 0.7% to 7.5%, respectively. Finally, the majority of the complications were classified as Grade I-II, according to the Clavien-Dindo Classification System. The MAP score is a useful tool for predicting not only the presence of APF during laparoscopic PNs but also various intraoperative and postoperative characteristics. It was found to be significantly associated with an increased operative time, estimated blood loss and intraoperative and postoperative complication rates.

Path Planning for a Wheel-Foot Hybrid Parallel-Leg Walking Robot.

Mobile robots require the ability to plan collision-free paths. This paper introduces a wheel-foot hybrid parallel-leg walking robot based on the 6-Universal-Prismatic-Universal-Revolute and 3-Prismatic (6UPUR + 3P) parallel mechanism model. To enhance path planning efficiency and obstacle avoidance capabilities, an improved artificial potential field (IAPF) method is proposed. The IAPF functions are designed to address the collision problems and issues with goals being unreachable due to a nearby problem, local minima, and dynamic obstacle avoidance in path planning. Using this IAPF method, we conduct path planning and simulation analysis for the wheel-foot hybrid parallel-legged walking robot described in this paper, and compare it with the classic artificial potential field (APF) method. The results demonstrate that the IAPF method outperforms the classic APF method in handling obstacle-rich environments, effectively addresses collision problems, and the IAPF method helps to obtain goals previously unreachable due to nearby obstacles, local minima, and dynamic planning issues.

Risk field modeling of urban tunnel based on APF.

OBJECTIVE: The purpose of this paper is to explore the changing laws of driving safety in the complex and changing driving environment in urban tunnels, to analyze the evolution of driving risk fields caused by changes in adjacent vehicles, driving behavior characteristics and road environment, and to reveal the formation mechanism of tunnel driving danger zones. METHODS: The kinetic field, behavioral field and potential field models are constructed according to the APF theory. The driving safety risks arising from the surrounding vehicles, driving behavior characteristics and changes in the tunnel environment are analyzed in the process of driving from the open section to the exit of the tunnel. RESULTS: The magnitude of the risk field force is inversely proportional to the spacing of the vehicles and the distance between the tunnel sidewalls, and is proportional to the relative speed between the vehicles and the slope of the longitudinal slope. Under the same conditions, the vehicle at the entrance and exit of the tunnel is subjected to a greater force of travel risk than inside the tunnel, and the effect of speed on the force of the risk field is greater than the distance. CONCLUSIONS: The established model better describes the trend of driving risk during the driving of vehicles in urban tunnels, and the research findings can provide theoretical support for the design and traffic management of urban tunnels.

Improved RRT* Algorithm for Disinfecting Robot Path Planning.

In this paper, an improved APF-GFARRT* (artificial potential field-guided fuzzy adaptive rapidly exploring random trees) algorithm based on APF (artificial potential field) guided sampling and fuzzy adaptive expansion is proposed to solve the problems of weak orientation and low search success rate when randomly expanding nodes using the RRT (rapidly exploring random trees) algorithm for disinfecting robots in the dense environment of disinfection operation. Considering the inherent randomness of tree growth in the RRT* algorithm, a combination of APF with RRT* is introduced to enhance the purposefulness of the sampling process. In addition, in the context of RRT* facing dense and restricted environments such as narrow passages, adaptive step-size adjustment is implemented using fuzzy control. It accelerates the algorithm's convergence and improves search efficiency in a specific area. The proposed algorithm is validated and analyzed in a specialized environment designed in MATLAB, and comparisons are made with existing path planning algorithms, including RRT, RRT*, and APF-RRT*. Experimental results show the excellent exploration speed of the improved algorithm, reducing the average initial path search time by about 46.52% compared to the other three algorithms. In addition, the improved algorithm exhibits faster convergence, significantly reducing the average iteration count and the average final path cost by about 10.01%. The algorithm's enhanced adaptability in unique environments is particularly noteworthy, increasing the chances of successfully finding paths and generating more rational and smoother paths than other algorithms. Experimental results validate the proposed algorithm as a practical and feasible solution for similar problems.

A study of the roles of some immunological biomarkers in the diagnosis of rheumatoid arthritis.

Autoimmune rheumatoid arthritis (RA) is a systemic condition closely correlated with a variety of autoantibodies (Abs) that could be considered diagnostic and prognostic markers. The current research was designed to detect the diagnostic values for a number (n) of these auto-Abs in RA detection and to evaluate the accuracy of a combined diagnostic scheme. This prospective study was conducted between September 2021 and August 2022 and included 110 subjects with RA, 70 individuals with other autoimmune disorders as positive controls (PC), and 50 unrelated, apparently healthy individuals as healthy controls (HC). The eligibility criteria for all study groups were followed stringently. An enzyme-linked immunosorbent assay (ELISA) was employed to measure rheumatoid factors (RF), cyclic citrullinated peptide antibodies (CCP-Abs), mutated citrullinated vimentin antibodies (MCV-Abs), anti-perinuclear factor antibodies (APF-Abs), and anti-keratin antibodies (AKA). We calculated the specificity, sensitivity, and predictive values of all auto-Abs. Significantly higher levels of anti-CCP-Abs, anti-MCV-Abs, APF-Abs, and AKAs were reported in the RA patients compared to the HC and PC subjects. RF levels, however, were only statistically elevated when compared to the HC individuals. Anti-APF-Abs had a higher sensitivity rate (70.9%), and anti-CCP-Abs had a higher specificity rate (94.16%) compared to other auto-Abs, whereas the combined detection scheme revealed a higher sensitivity (81.81%) and excellent specificity (90.83%) compared to the two former auto-Abs. Anti-perinuclear factor-Ab was a highly sensitive test, and CCP-Ab was a surpassingly specific assay for identifying RA. Furthermore, the combined detection scheme is an essential serological approach for RA diagnosis and crucial in differentiating this disease from other autoimmune diseases, thus promoting early diagnosis and treatment.

Novel Second-Order Fully Differential All-Pass Filter Using CNTFETs.

In this paper, a new carbon nanotube field effect transistor (CNTFET)-based second-order fully differential all-pass filter circuit is presented. The realized filter uses CNTFET-based transconductors and grounded capacitors. An active-only second-order fully differential all-pass filter circuit topology is also presented by replacing the grounded capacitance with a CNTFET-based varactor to achieve filter tunability. By controlling the varactor capacitance, active-only second-order fully differential all-pass filter tunability in the range of 15 GHz to 27.5 GHz is achieved. The proposed active-only circuit works on -oltage, low-power dissipation and high tunable pole frequency. The realized circuit operations are verified through the HPSPICE simulation tool. Deng's CNTFET model is utilized to verify the filter performances at the 16 nm technology node. It is seen that the proposed filter simulation justifies the theoretical predictions and works efficiently in the deep-submicron technology.

On the Creation and Optical Microstructure Characterisation of Additively Manufactured Foam Structures (AMF).

Plastic-based additive manufacturing processes are becoming increasingly popular in the production of structural parts. Based on the idea of lightweight design and the aim of extending the functionality of additive structures, the production of additively manufactured foam structures has emerged as a new field of application. The optical characterisation of these structures is of particular importance for process adjustments and the identification of (unwanted) changes in the foam structure. The degree of foaming and the fineness of a foam structure are of interest at this point. In this context, only the part of a structure dominated by foam pores is considered a foam structure. So far, there are no sophisticated methods for such an optical characterisation. Therefore, in this work, microscope images of manufactured as well as artificially created additively manufactured foam structures were evaluated. On these images, the features porosity, pore size, pore amount and a measure for the textural change were determined in order to obtain information about changes within an additively manufactured foam structure. It is shown that additive structures show changing pore shapes depending on the orientation of the cutting plane, although there are no changes in the foaming behaviour. Therefore, caution is required when identifying changes within the foam structure. It was also found that, owing to the additive process, the total porosity is already set in the slicing process and remains constant even if the degree of foaming of individual tracks is changed. Therefore, the degree of foaming cannot be determined on the basis of the total porosity, but it can be assessed on the basis of the formation of large networks of process-related pores.

A Case of Vaccine-Induced Thrombocytopenic Thrombosis Manifesting as Cerebral Venous Thrombosis and Intracerebral Bleed.

Vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare but detrimental syndrome that has been most commonly reported after the administration of vaccination for the prevention of viral infections. VITT often presents with thrombosis at unusual sites such as cerebral venous sinuses, portal, splanchnic or hepatic veins, in association with thrombocytopenia and elevated anti-platelet factor 4 (aPF-4) antibodies. We describe the case of a young male patient who developed thrombocytopenia, cerebral sinus venous thrombosis, and intracerebral bleed 12 days after receiving the Ad26.COV2.S (Janssen/Johnson&Johnson) COVID-19 vaccine.

EMPC with adaptive APF of obstacle avoidance and trajectory tracking for autonomous electric vehicles.

In this paper, event-triggered model predictive control (EMPC) with adaptive artificial potential field (APF) is designed to realize obstacle avoidance and trajectory tracking for autonomous electric vehicles. An adaptive APF cost function is added to achieve obstacle avoidance and guarantee stability. The optimization problem for MPC is feasible by considering a special obstacle avoidance constraint. An event-triggered mechanism is proposed to reduce computational burden and ensure effectiveness of obstacle avoidance. Input and state constraints of autonomous electric vehicles are considered in both feasibility and stability by a robust terminal set. Effectiveness of both obstacle avoidance and trajectory tracking is shown by experimental results on autonomous electric vehicles.

3D printed PLGA implants: APF DDM vs. FDM.

3D Printing offers a considerable potential for personalized medicines. This is especially true for customized biodegradable implants, matching the specific needs of each patient. Poly(lactic-co-glycolic acid) (PLGA) is frequently used as matrix former in biodegradable implants. However, yet relatively little is known on the technologies, which can be used for the 3D printing of PLGA implants. The aim of this study was to compare: (i) Arburg Plastic Freeforming Droplet Deposition Modeling (APF DDM), and (ii) Fused Deposition Modeling (FDM) to print mesh-shaped, ibuprofen-loaded PLGA implants. During APF DDM, individual drug-polymer droplets are deposited, fusing together to form filaments, which build up the implants. During FDM, continuous drug-polymer filaments are deposited to form the meshes. The implants were thoroughly characterized before and after exposure to phosphate buffer pH 7.4 using optical and scanning electron microscopy, GPC, DSC, drug release measurements and monitoring dynamic changes in the systems' dry & wet mass and pH of the bulk fluid. Interestingly, the mesh structures were significantly different, although the device design (composition & theoretical geometry) were the same. This could be explained by the fact that the deposition of individual droplets during APF DDM led to curved and rather thick filaments, resulting in a much lower mesh porosity. In contrast, FDM printing generated straight and thinner filaments: The open spaces between them were much larger and allowed convective mass transport during drug release. Consequently, most of the drug was already released after 4 d, when substantial PLGA set on. In the case of APF DDM printed implants, most of the drug was still entrapped at that time point and substantial polymer swelling transformed the meshes into more or less continuous PLGA gels. Hence, the diffusion pathways became much longer and ibuprofen release was controlled over 2 weeks.

Evaluation of Enamel Acid Resistance and Whitening Effect of the CAP System.

This study aimed to compare the effectiveness of a novel professional tooth-strengthening system and a conventional caries-prevention method that involved the use of high fluoride concentrations, to determine whether the system has a whitening effect. Bovine tooth-enamel samples were treated with fluoride gel (conventional APF method) or a mixture of citric acid gel, calcium phosphate (α-TCP), and fluoride gel, referred to as the CAP system; these treatments were performed to generate an acid-resistant layer on the enamel surface. For the evaluation of the acid resistance, a cyclic experiment, involving a 1-h remineralization and a 24-h acid treatment, was conducted thrice after the treatments. The height profiles were observed using a 3D-measuring laser microscope and the hardness was evaluated by Vickers hardness test. The morphological changes in the surface and cross-section of the enamel were observed by scanning electron microscopy. To evaluate the whitening effect, the enamel was ground until the color of the underlying dentin was recognizable; the CAP system was applied once, and the color change was measured using a color difference meter. As a result, it was confirmed that an acid-resistant layer was formed on the tooth surfaces treated with the CAP system, and a whitening effect was obtained.

An investigation into the effects of geometric scaling and pore structure on drug dose and release of 3D printed solid dosage forms.

A range of 3D printing methods have been investigated intensively in the literature for manufacturing personalised solid dosage forms, with infill density commonly used to control release rates. However, there is limited mechanistic understanding of the impacts of infill adjustments on in vitro performance when printing tablets of constant dose. In this study, the effects and interplay of infill pattern and tablet geometry scaling on dose and drug release performance were investigated. Paracetamol (PAC) was used as a model drug. An immediate release erodible system (Eudragit E PO) and an erodible swellable system (Soluplus) were prepared via wet granulation into granules and printed using Arburg Plastic Freeforming (APF). Both binary formulations, despite not FDM printable, were successfully APF printed and exhibited good reproducibility compared to pharmacopoeia specification. The physical form of the drug and its integrity following granulation and printing was assessed using DSC, PXRD and ATR-FTIR. Two infill patterns (SM1 and SM2) were employed to print tablets with equal porosity, but different pore size, structure and surface area to volume ratio (SA/V). Geometry scaling (tablet height and diameter) of Eudragit-PAC tablets was not found to significantly influence the release rate of the tablets with 30 to 70% infill density. When increased to 90% infill density, geometric scaling was found to have a significant effect on release rate with the constant diameter tablet releasing faster than the constant height tablet. Soluplus-PAC tablets printed using different infill patterns demonstrated similar release profiles, due to swelling. Geometric parameters were found to significantly influence release profiles for tablets printed at certain infill densities giving new insight into how software parameters can be used to tune drug release.

Layer-By-Layer Self-Assembled Dip Coating for Antifouling Functionalized Finishing of Cotton Textile.

The fouling of surfaces such as textiles is a major health challenge, and there is a continuous effort to develop materials and processes to overcome it. In consideration of this, this study regards the development of antifouling functional nanoencapsulated finishing for the cotton textile fabric by employing a layer-by-layer dip coating technique. Antifouling textile finishing was formulated by inducing the nanoencapsulation of the antifouling functional group inside the hydrophobic polymeric shell. Cotton fabric was taken as a substrate to incorporate antibacterial functionality by alternatively fabricating multilayers of antifouling polymeric formulation (APF) and polyelectrolyte solution. The surface morphology of nanoencapsulated finished textile fabric was characterized through scanning electron microscopy to confirm the uniform distribution of nanoparticles on the cotton textile fabric. Optical profilometry and atomic force microscopy studies indicated increased surface roughness in the coated textile substrate as compared to the uncoated textile. The surface thickness of the fabricated textile increased with the number of deposited bilayers on the textile substrate. Surface hydrophobicity increased with number of coating bilayers with θ values of x for single layer, up to y for 20 bilayers. The antibacterial activity of the uncoated and layer-by-layer coated finished textile was also evaluated. It was significant and exhibited a significant zone of inhibition against microbial strains Gram-positive S. aureus and Gram-negative E. coli. The bilayer coating exhibited water repellency, hydrophobicity, and antibacterial activity. Thus, the fabricated textile could be highly useful for many industrial and biomedical applications.

Endobronchial blood-patch: A novel technique for a persistent pleural air leak.

Introduction: Patients with severe COVID-19 Pneumonia requiring prolonged mechanical ventilation have an increased incidence of pneumothorax. Mechanically ventilated patients who are critically ill and develop a persistent air leak from pneumothorax are poor candidates for surgical repair. As the persistent air leak can be a significant barrier to vent-weaning and clinical stability, these patients present a unique clinical challenge. Clinical case: A 65-year-old male intubated and on prolonged mechanical ventilation for severe COVID-19 Pneumonia developed a pneumothorax complicated by a persistent alveolar-pleural fistula with a persistent air-leak. Given his critical state with ongoing pressor requirements and elevated vent requirements, surgical repair was not an option. A bedside bronchoscopy occlusion study with isolation of the air leak, and subsequent autologous endobronchial blood-patch repair with thrombin was performed with rapid and definitive resolution of the air leak. The patient progressed favorably, ultimately being weaned from the ventilator, decannulated, and walking out of the hospital. Conclusion: In critically ill ventilated patients with pneumothorax complicated by a persistent air-leak, bedside endobronchial evaluation and blood-patch repair is a feasible approach to management.

Effectiveness of Nanoparticle-Based Acidulated Phosphate Fluoride (APF) Gel on Surface Enamel Fluoride Uptake: an Interventional Study.

Statement of the Problem: Despite topical fluoride being used for over 50 years in caries prevention, its complete potential in terms of formation of fluorapatite enamel and prolonged surface retention has not been harnessed. Purpose: This study aimed to assess the effectiveness of nanoparticle based acidulated phosphate fluoride (APF) gel on surface enamel fluoride uptake through split mouth design over a period of six months, on patients undergoing orthodontic treatment and indicated for bilateral extraction of premolars on at least one of the arch. Materials and Method: A split mouth non randomized clinical trial was performed. Each of the 30 participants received one application of 4 minutes duration of both the intervention: Right half of the mouth received nanoparticle based APF gel, and left half of the mouth received conventional APF gel (16 Oz Pascal Corp.; strawberry flavor). Bilateral acid etch biopsy of enamel surface was take at 3 intervals- baseline,24 hours and 30 days. Using 1ml of 0.5M perchloric acid, acid etch enamel biopsy was taken for all the study subjects at 3 intervals of time (baseline, 24 hours and 30 days), bilaterally on the buccal and palatal/lingual surface of maxillary or mandibular premolars indicated for extraction, using 1 (l of 0.5M perchloric acid. After the premolars were extracted, scanning electron microscope (SEM) analysis was done to determine the surface characteristics of enamel in both groups. Results: Overall, both fluoride uptake and depth of biopsy remained significant even after controlling for the covariates (time, group) individually and simultaneously (p< 0.05). Further analysis showed that fluoride uptake was significantly increased and biopsy depth significantly decreased in the nanoparticle based APF gel group at 24 hour and 30 day evaluation respectively. Conclusion: By reducing the size of sodium fluoride to increase the surface enamel uptake, our results support the use of this top down approach as a promising strategy for effective delivery of topical fluorides. This highlights that the top down approach of nanoscience to reduce the size active compound sodium fluoride has increased the uptake and retention of surface enamel fluoride.

Direct Granule Feeding of Thermal Droplet Deposition 3D Printing of Porous Pharmaceutical Solid Dosage Forms Free of Plasticisers.

PURPOSE: To develop a new direct granule fed 3D printing method for manufacturing pharmaceutical solid dosage forms with porous structures using a thermal droplet deposition technology. METHODS: Eudragit® E PO was used as the model polymer, which is well-known to be not FDM printable without additives. Wet granulation was used to produce drug loaded granules as the feedstock. The flow and feedability of the granules were evaluated. The physicochemical properties and in vitro drug release performance of the granules and the printed tablets were fully characterised. RESULTS: Using the method developed by this study, Eudragit E PO was printed with a model drug into tablets with infills ranging from 30-100%, without additives. The drug was confirmed to be molecularly dispersed in the printed tablets. The printing quality and performances of the porous tablets were confirmed to be highly compliant with the pharmacopeia requirement. The level of infill density of the porous tablets had a significant effect on their in vitro drug release performance. CONCLUSION: This is the first report of thermal droplet deposition printing via direct granule feeding. The results of this study demonstrated that this new printing method can be used as a potentially valuable alternative for decentralised pharmaceutical solid dosage form manufacturing.