Tandem rapid manufacturing of Inconel-625 using laser assisted and plasma transferred arc depositions

This paper presents an investigation on deposition of Inconel-625 using laser rapid manufacturing (LRM) and plasma transferred arc (PTA) deposition in
individual and tandem mode. LRM has advantages in terms of dimensional accuracy, improved mechanical properties,finer process control, reduced heat input and lower thermal distortion, while PTA scores more in terms of lower initial investment, lower running cost and higher deposition rate.To quantify the clubbed advantages and limitations of both processes, these were studied individually and in tandem. A number of samples were deposited at different process parameters like power, scan speed, powder feed rate. They were subjected to tensile test, adhesion-cohesion test,impact test and micro hardness measurement. The results of individual tests showed the comparable mechanical properties with ±20% variation. The mixed dendritic-cellular and dendritic-columnar microstructures were respectively observed for LRM and PTA deposits with a distinct interface for the case of tandem deposition. The interface
strength of tandem deposits was evaluated employing adhesion-cohesion test, and it was found to be (325 ±35) MPa. The study confirmed the viability of LRM and PTA deposition in tandem for hybrid manufacturing.     

Aerosol assisted chemical vapour deposition of germanium thin films using organogermanium carboxylates as precursors and formation of germania films

Diethyl germanium bis-picolinate, [Et₂Ge(O₂CC₅H₄N)₂], and trimethyl germanium quinaldate, [Me₃Ge(O₂CC₉H₆N)], have been used as precursors for deposition of thin films of germanium by aerosol assisted chemical vapour deposition (AACVD). The thermogravimetric analysis revealed complete volatilization of complexes under nitrogen atmosphere. Germanium thin films were deposited on silicon wafers at 700°C employing AACVD method. These films on oxidation under an oxygen atmosphere at 600°C yield GeO₂. Both Ge and GeO₂ films were characterized by XRD, SEM and EDS measurements. Their electrical properties were assessed by current?Cvoltage (I?CV) characterization.     

Microneedle assisted iontophoretic transdermal delivery of prochlorperazine edisylate

This paper investigates the microneedle (MN) mediated in vitro transdermal iontophoretic delivery of prochlorperazine edisylate (PE) across dermatomed human skin. The Dermaroller? induced microchannels were visualized using methylene blue staining and scanning electron microscopy. In vitro skin permeation studies were performed using vertical static Franz diffusion cells. Iontophoretic protocols involved application of direct current at a density of 0.4 mA/cm(2) using Ag as an anode and Ag/AgCl as a cathode. The effect of PE concentration (20, 50 and 100 mg/mL), number of passes of microneedles (0, 5, 10 and 20) on both iontophoretic and passive delivery of PE was studied. The Dermarollertm was found to successfully breach the skin barrier and a linear relationship (r(2) = 0.99) was observed between the number of passes of the Dermaroller? and the number of microchannels created. Passive transdermal flux of PE (0.060 ± 0.003 μg/cm(2)/h) at 50 mg/mL donor PE concentration) was low and increased (4.15 ± 0.57 μg/cm(2)/h) with the application of direct current. Application of iontophoresis in conjunction with microneedle pre-treatment resulted in enhanced flux (4.90 ± 0.39 μg/cm(2)/h at 50 mg/mL donor PE concentration) of PE. The projected transdermal PE flux indicates that a 9 cm(2) patch could deliver PE in a sufficient amount to maintain therapeutic levels of the drug. In conclusion, microneedles when used in conjunction with iontophoresis significantly enhanced the transdermal delivery of PE and it may be feasible to develop an iontophoretic transdermal patch that could be integrated with MN.     

Mooring system design optimization using a surrogate assisted multi-objective genetic algorithm

This article presents a novel framework for the multi-objective optimization of offshore renewable energy mooring systems using a random forest based surrogate model coupled to a genetic algorithm. This framework is demonstrated for the optimization of the mooring system for a floating offshore wind turbine highlighting how this approach can aid in the strategic design decision making for real-world problems faced by the offshore renewable energy sector. This framework utilizes validated numerical models of the mooring system to train a surrogate model, which leads to a computationally efficient optimization routine, allowing the search space to be more thoroughly searched. Minimizing both the cost and cumulative fatigue damage of the mooring system, this framework presents a range of optimal solutions characterizing how design changes impact the trade-off between these two competing objectives.     

Functionalized nano-magnetic particles for an in vivo delivery system

Nanotechnologies to allow the nondisruptive introduction of carriers in vivo have wide potential for therapeutic delivery system. We have prepared functional nano-magnetic particles (d = 3 nm) by silanization with (3-aminopropyl) triethoxysilane. For the purpose of functionalizing the surface of the nanoparticles with amino groups for subsequent cross-linking with pharmaceuticals and biomolecules. The extremely small particles were successfully introduced into living cells without any further modification to enhance endocytic internalization, such as the use of a cationic help. The cells containing the internalized particles continued to thrive, indicating that the particles have no inhibition effect for mitosis. In addition, the particles could be incorporated into the subcutaneous tissue of mouse's ear from ear skin and were able to be localized upon application of an external magnetic field. The functionalized nano-magnetic particles are expected to be useful as a new delivery tool.     

Thermally assisted recording of holographic gratings in semicrystalline azobenzene-containing polymers

We examine optically induced birefringence in semicrystalline azopolymer films that are held at glass-transition temperature Tg. The birefringence increases markedly after interception of the pump beam; the saturation value depends on exposure time. In addition, the induced birefringence is completely erased by irradiation with a circularly polarized beam at Tg. Using this thermally assisted method, we demonstrate the holographic recording of a test image. The intensity of the diffracted beam also increases after interception of the writing beams. Furthermore, the retrieved image is found to have a resolution of approximately 30 lp/mm. This resolution is comparable with that of the optical setup that is used. Accordingly, the thermally assisted recording by use of semicrystalline azopolymers is a promising method for reversible holographic storage.     

Aerosol assisted deposition of melamine-formaldehyde resin: Hydrophobic thin films from a hydrophilic material

An intrinsically hydrophilic melamine-formaldehyde thin film (water contact angle of 34° for a cast flat surface) was deposited on a glass substrate using aerosol assisted chemical vapour deposition. The resultant resin films showed a highly developed microstructure consisting of spherical structures that were agglomerated into towers. The surface wetted via a Cassie-Baxter mechanism with air trapped underneath the water droplets and resultant water contact angles as high as 135°. Film thickness and coverage were crucial in determining the wetting properties. Films with limited deposition gave hydrophilic results, whereas thicker films greater than 4 μm were superhydrophilic. This behaviour could be explained by the ease of trapping air under the coating. It is shown that the water wetting properties of a single material can be altered from superhydrophilic to near superhydrophobic by controlling the surface microstructure in a single-step aerosol route.     

Aerosol assisted chemical vapour deposition control parameters for selective deposition of tungsten oxide nanostructures

Tungsten oxide films were deposited via Aerosol Assisted Chemical Vapour Deposition (AACVD) from the single-source precursor W(OPh)6. Film morphology and optimum deposition temperatures for formation of quasi-one-dimensional structures is influenced by the solvent 'carrier' used for deposition of the films with bulk porous films and nanostructured needles, hollow tubes and fibres obtained dependent on the solvent used and the deposition temperature. This influence of solvent could be exploited for the synthesis of other nanomaterials, and so provide a new and versatile route to develop and integrate nanostructured materials for device applications.     

Location of departmental pickup and delivery points for an AGV system

In this paper, two algorithms are developed for the determination of pickup and delivery point locations for an AGV system. The first algorithm is applicable to general layout configurations and seeks solutions until the local optimum is reached by comparing relative locations of pickup and delivery points. The second algorithm generates solutions with a minimal amount of computational time due to its exploitation of the structural feature of departmental layouts. Computational results are provided to check the quality of solutions from each algorithm.     

Design of self-microemulsifying drug delivery systems using a high-throughput formulation screening system

Purpose: A high-throughput formulation screening (HTFS) system that enabled to rapidly and efficiently select self-microemulsifying drug delivery system (SMEDDS) formulations has been developed in our previous study. The purpose of this study was to investigate the applicability of the HTFS system to SMEDDS designs. Methods: A poorly soluble drug (Nilvadipine), an oil (Sefsol-218), 11 hydrophilic surfactants (HS), and 10 lipophilic surfactants (LS) were used. Formulations were prepared and SMEDDS formulations were chosen by the HTFS system. A HS with the largest number of SMEDDS formulations was selected. In the selected HS system, a LS with the largest number of SMEDDS formulations was selected. Formulations with minimum turbidity at each ratio of the selected HS/LS were chosen as optimized formulations. Results: A total of 2455 formulations were prepared and SMEDDS formulations were selected using the HTFS system. From the screening data, HCO60 was selected as a superior emulsifiable HS, and Plurol (PLUROL OLEIQUE CC497) was selected as a suitable LS to HCO60. Five optimized formulations were chosen from the HCO60/Plurol system. The formulations formed fine microemulsions (<33.6 nm) without phase separation and drug precipitation. These formulation designs were conducted using 600 mg of the drug at a rate of 400 formulations/person/day. Conclusion: SMEDDS formulations could be rapidly and efficiently designed using the HTFS system.     

Optimization and characterization of gastroretentive floating drug delivery system using Box-Behnken design

Context: One among many strategies to prolong gastric residence time and improve local effect of the metronidazole in stomach to eradicate Helicobacter pylori in the treatment of peptic ulcer was floating drug delivery system particularly effervescent gastroretentive tablets.

Objective: The objective of this study was to prepare and evaluate, effervescent floating drug delivery system of a model drug, metronidazole.

Methods: Effervescent floating drug delivery tablets were prepared by wet granulation method. A three-factor, three levels Box-Behnken design was adopted for the optimization. The selected independent variables were amount of hydroxypropyl methylcellulose K 15M (X₁), sodium carboxy methylcellulose (X₂) and NaHCO₃ (X₃). The dependent variables were floating lag time (Y_FLT), cumulative percentage of metronidazole released at 6th h (Y₆) and cumulative percentage of metronidazole released at 12th h (Y₁₂). Physical properties, drug content, in vitro floating lag time, total floating time and drug release behavior were assessed.

Results: Y_FLT range was found to be from 1.02 to 12.07?min. The ranges of other responses, Y₆ and Y₁₂ were 25.72?±?2.85 to 77.14?±?3.42 % and 65.47?±?1.25 to 99.65?±?2.28 %, respectively. Stability studies revealed that no significant change in in vitro floating lag time, total floating time and drug release behavior before and after storage.

Conclusion: It can be concluded that a combination of hydroxypropyl methylcellulose K 15M, sodium carboxy methylcellulose and NaHCO₃ can be used to increase the gastric residence time of the dosage form to improve local effect of metronidazole.     

Target delivery and controlled release of the chemopreventive drug sulindac by using an advanced layered double hydroxide nanomatrix formulation system

Target delivery and controlled release of the chemopreventive drug sulindac that possesses low water solubility present a great challenge for its pharmaceutical industry. Here, we offered an advanced nanomatrix formulation system of sulindac based on layered double hydroxide materials. The X-ray analysis and infrared spectroscopy confirmed the incorporation of sulindac into the gallery of the layered double hydroxides. The incorporation ratios of sulindac were recorded to be 45, 31 and 20 for coprecipitation, anion-exchange and reconstruction techniques, respectively. The scanning electron microscopy showed a nanomatrix-structure of ~50 nm. The release studies of sulindac-nanomatrix showed a 96% controlled release at the small intestine solution during 3 h(s), indicating an enhancement in the dissolution profile of sulindac after the matrix formation. The layered structure of the matrix supplied sulindac with a well-ordered structure and a relatively hydrophobic microenvironment that controlled the guest hydrolysis and reactivity during the release process. The laminar structure of layered double hydroxides offered a safe preservation for sulindac against photodecarboxylation, and enhanced the drug thermal stability from 190 to 230° C. The ionic electrostatic interaction of sulindac through its acidic group with layered double hydroxides demolished the gastrointestinal ulceration.     

Improvement of radiotherapy treatment delivery accuracy using an electronic portal imaging device

Reliable application of advanced external beam techniques for the treatment of patients with cancer, such as intensity modulated radiotherapy, requires an adequate quality assurance programme for the verification of the dose delivery. Accurate patient positioning is mandatory because of the steep dose gradients outside the tumour volume. Owing to the increased complexity of the treatment planning and delivery techniques, verification of the dose delivery before and during the actual patient treatment is equally important. For this purpose, a quality assurance programme has been established in our clinic that is primarily based on measurements with electronic portal imaging devices. To minimise systematic set-up errors, the patient positioning is measured in the first few treatment fractions and a set-up correction is applied in the subsequent ones. Before the first treatment fraction, portal dose measurements are performed for each treatment field with the electronic portal imaging device to verify that the planned fluence distribution is correctly delivered at the treatment unit. Dosimetric measurements are also performed during patient treatment to derive the actually delivered fluence maps. By combining this information with knowledge on the patient set-up, the delivered 3-D dose distribution to both the tumour and sensitive organs may be assessed. However, for the highest accuracy, exact knowledge on the (internal) patient geometry during treatment, e.g. using a cone-beam CT, is required.     

Differentiation of preosteoblasts using a delivery system with BMPs and bioactive glass microspheres

Bone morphogenetic proteins (BMPs) and 45S5 Bioglass microspheres (bioactive GM) can increase the differentiation of osteoblasts. Recombinant human BMP-2 (rhBMP-2) is presently the BMP most frequently used in delivery systems and it has already been used in clinical bone healing studies. We have developed a delivery system that combines a collagen Type I gel, BMP and bioactive GM. Since BMP-9 seems to be more osteogenic than BMP-2, we compared the differentiation of MC3T3-E1 preosteoblasts induced by our delivery system containing either a peptide derived from BMP-9 (pBMP-9), or rhBMP-2, both at 100 ng/mL. After 5 days, alkaline phosphatase staining showed that pBMP-9 induced more differentiation than rhBMP-2 in all experimental conditions. Also, bioactive GM increased this BMP effect. Since preosteoblasts secreted matrix metalloproteinases (MMPs) that can degrade collagen, we then studied the influence of the delivery system on MMPs production. We observed that MMP-2 was the major MMP involved in all experimental conditions. In addition, pBMP-9 with bioactive GM generated less MMP-2 than did rhBMP-2 on days 3 and 5. Thus, a delivery system using collagen Type I gel with pBMP-9 and bioactive GM seems to be a promising system for bone regeneration.     

Experimental validation of forming simulations of fabric reinforced polymers using an unsymmetrical mould configuration

Forming simulations are performed on woven textile composites using (a) an explicit finite element method and (b) a kinematic mapping scheme. Both methods are compared with experimental results that are obtained by determining the fiber orientations of glass/PP woven composites thermoformed on an extended hemispherical shaped mould with different orientations of the blank. It was found that the kinematic mapping approach severely fails in predicting the fiber reorientation that occurs during stamp forming for non-symmetrical forming configurations. The FEM-simulation gives a reasonably good prediction of the fiber reorientation and seems the most promising technique in having good draping simulations. The reported experimental results can be used as a benchmarking case in the assessment of the quality of forming simulation methods.     

Self-assembled liquid crystalline nanoparticles as an ophthalmic drug delivery system. Part II: optimization of formulation variables using experimental design

In the field of keratoconus treatment, a lipid-based liquid crystal nanoparticles system has been developed to improve the preocular retention and ocular bioavailability of riboflavin, a water-soluble drug. The formulation of this ophthalmic drug delivery system was optimized by a simplex lattice experimental design. The delivery system is composed of three main components that are mono acyl glycerol (monoolein), poloxamer 407 and water and two secondary components that are riboflavin and glycerol (added to adjust the osmotic pressure). The amounts of these three main components were selected as the factors to systematically optimize the dependent variables that are the encapsulation efficiency and the particle size. In this way, 12 formulas describing experimental domain of interest were prepared. Results obtained using small angle X-rays scattering (SAXS) and cryo-transmission electron microscopy (cryo-TEM) evidenced the presence of nano-objects with either sponge or hexagonal inverted structure. In the zone of interest, the percentage of each component was determined to obtain both high encapsulation efficiency and small size of particles. Two optimized formulations were found: F7 and F1. They are very close in the ternary phase diagram as they contain 6.83% of poloxamer 407; 44.18% and 42.03% of monoolein; 46.29% and 48.44% of water for F7 and F11, respectively. These formulations displayed a good compromise between inputs and outputs investigated.     

Conjugated polymers as robust carriers for controlled delivery of anti-inflammatory drugs

Conjugated polymers due to their reversible transition between the redox states are potentially able to immobilise and release ionic species. In this study, we have successfully developed a conducting polymer system based on poly(3,4-ethylenedioxythiophene) (PEDOT) for electrically triggered, local delivery of an ionic form of ibuprofen (IBU), a non-steroidal anti-inflammatory, and analgesic drug. It was shown that by changing the electropolymerisation conditions, the polymer matrix of specified IBU content can be synthesised. The electrochemical synthesis has been optimised to obtain the conducting matrix with the highest possible drug content. The process of electrically stimulated drug release has been extensively studied in terms of the dynamics of the controlled IBU release under varying conditions. The maximum concentration of the released IBU, 0.66 (±0.10) mM, was observed at the applied potential E = ?0.5 V (vs. Ag/AgCl). It was demonstrated that the immobilisation-release procedure can be repeated several times making the PEDOT matrix promising materials for controlled drug release systems applied e.g. in neuroprosthetics.     

Optimization of finned-tube condensers using an intelligent system

The refrigerant circuitry influences a heat exchanger's attainable capacity. Typically, a design engineer specifies a circuitry and validates it using a simulation model or laboratory test. The circuitry optimization process can be improved by using intelligent search techniques. This paper presents experiments with a novel intelligent optimization module, ISHED (Intelligent System for Heat Exchanger Design), applied to maximize capacity through circuitry design of finned-tube condensers. The module operates in a semi-Darwinian mode and seeks refrigerant circuitry designs that maximize the condenser capacity for specified operating conditions and condenser slab design constraints. Examples of optimization runs for six different refrigerants are included. ISHED demonstrated the ability to generate circuitry architectures with capacities equal to or superior to those prepared manually, particularly for cases involving non-uniform air distribution.     

Fabrication of flat capped carbon nanotubes using an arc-discharge method assisted with a Sm-Co catalyst

In this study, carbon nanotubes (CNTs) were fabricated using an arc-discharge method assisted with samarium-cobalt (Sm-Co) chloride as a catalyst. The optimal fabrication condition was determined through a series of experiments on various ambient conditions. Observations were completed using scanning electron microscopy (SEM), Raman spectroscopy, and tunneling electron microscopy (TEM); the main products we observed are well-structured multi-walled carbon nanotubes. By identifying the radial breathing modes (RBMs) of the Raman spectra with a TEM micrograph, we also observed a small number of single-walled carbon nanotubes. With the assistance of the Sm-Co chloride catalyst, the RBMs of the Raman spectra were measured in the ambient pressure of 760 torr. The TEM observations revealed that our nanotubes have good graphitic structures and almost no bamboo defects, which agrees with their Raman measurements with a high I_G/I_D ratio (~88). A perfect graphitic flat cap was found to be attached at the end of the nanotube. Simulation shows that by incorporating 5 carbon pentagons, it is possible to construct a flat capped carbon nanotube. The results of our experiment offer a unique approach to growing high quality CNTs. Such a flat capped structure may useful for further advanced application in nano-electronics and nano-optics.     

Aerosol assisted fabrication of metallic film/carbon fiber and heat treatment to form crystalline alloy film

Carbon fiber (CF) was catalytically activated with spark generated Pd aerosol nanoparticles. Metal (Ag, Au, Cu, and Pd) and alloy (Ni-P, Ni-Cu-P) electroless films were deposited on Pd aerosol activated CF using a range of deposition parameters including deposition rate in an electroless deposition bath. Sintering was applied to the alloy films on the CF to examine the crystallization behavior at 400 °C in a nitrogen atmosphere. Ni-Cu-P had a higher crystallinity than Ni-P after the treatment.