Resin Cast Research Articles

Moisture absorption process of epoxy resin and mechanical properties of its fiber composites

Abstract Epoxy resins are highly moisture absorbant when exposed to weather and environmental factors, which brings about a deterioration of durability and of mechanical properties in epoxy composites. In this paper, the effect of humidity on the durability and mechanical properties of epoxy resin and its composites was thoroughly studied for various time durations. It was found that moisture absorption increases linearly to the square root of time, following Fick's second law. Due to the resulting moisture absorption, the flexural strength and modulus of epoxy resin are impaired compared to dry samples. However, the strength retention rate of epoxy resin cast at a relative humidity of 60 % and 70 % are better than those of samples at relative humidity of 100 % and 90 %, a promising observation for assuring favorable application in high humidity environments. It is believed that this research will be beneficial for a wide and safe application of certain epoxy resin systems in harsh service environments.

Effect of different fixed detachable implant supported prosthesis materials on the stresses induced on the supporting structures

Objectives: This study was conducted to evaluate the effect of different implant supported fixed detachable prosthesis materials (chrome cobalt-acrylic and BioHPP (Bio-High Performance Polyether)) on the stresses induced on the supporting structures.Materials and methods: A maxillary completely edentulous resin cast was 3d printed with four implant sites (two straight anterior implants and two tilted posterior implants), mucosal space for mucosa simulation and vertical slots for strain gauges which were 1mm distal to the two distal implants. Four implant analogues were placed in their sites. Multiunit abutments were secured to the implants, then fixed detachable prostheses were fabricated. In this study two models were conducted: Group (A): Complete implant supported chrome cobalt-acrylic fixed detachable prosthesis. Group (B): Complete implant supported BioHPP fixed detachable prosthesis. Strain gauges were supplied with fully encapsulated grids and attached wires. Micro strains were recorded at each site of the strain gauges with enough time elapsed between each testing. The applied load started from 0 up to 100N. T test was used for comparison between the groups, at a significance level of P ≤0.05. Results: Group A (chrome cobalt- acrylic prosthesis) showed higher induced stresses on supporting structures compared to group B (BioHPP) during bilateral, unilateral, and oblique loading. Independent T test showed statistically significant difference between the studied groups, P value was <0.05.Conclusion: Unilateral loading was more traumatic to the implants as compared to bilateral loading. BioHPP prosthesis has damping effect as it transferred less stresses to the supporting structures compared to chrome cobalt- acrylic prosthesis.

Ameliorating Effects of Jixueteng in a Mouse Model of Porphyromonas gingivalis-Induced Periodontitis: Analysis Based on Gingival Microcirculatory System

Jixueteng, the dried stem of Spatholobus suberectus Dunn (Leguminosae), is a traditional Chinese herbal medicine that promotes blood circulation and can be used to treat blood stasis. In this study, we aimed to investigate the potential of Jixueteng as a preventive and therapeutic drug for periodontitis. We investigated the inhibitory effects of Jixueteng on Porphyromonas gingivalis ( P. gingivalis)-induced gingival circulatory disturbances in mice. Seventy-two male C57BL/6N mice (4-week-old) were randomly divided into the following four groups of 12 mice each. Group 1 served as the P. gingivalis noninfected control (control group). Group 2 was administered Jixueteng extract in drinking water to P. gingivalis noninfected control mice. Group 3 was infected orally with P. gingivalis; and group 4 was administered Jixueteng extract in drinking water and then infected with P. gingivalis. To evaluate the effect of Jixueteng on gingival microcirculation systems, we examined gingival blood flow (GBF) in oral microcirculation in vivo in a mouse model of periodontitis. Gingival reactive hyperemia (GRH) was determined using laser Doppler flowmetry. GRH was elicited by the release of occlusive gingival compression by the laser Doppler probe (diameter 1.0 mm) for 1 min. GRH was estimated by basal blood flow, maximum response (Peak), the time taken for the maximum response to fall to one half (T1/2) and increased total amount of blood flow (Mass). Furthermore, to determine the effect of an oral application of P. gingivalis and/or Jixueteng on GBF and gingival microvessel ultrastructure, morphological analysis of gingival microvessels was performed by using a vascular resin cast model. Administration of Jixueteng to P. gingivalis-infected animals significantly reduced GRH, especially T1/2 and Mass, compared to that in P. gingivalis-infected animals. Alternatively, in the morphological analysis, reduction of the gingival capillary network which resulted from P. gingivalis-infection was improved by Jixueteng administration. Since Jixueteng ameliorates P. gingivalis infection-induced gingival circulatory disturbance, it may be useful in the treatment of P. gingivalis-induced periodontitis.

Anatomy models using Silicone Moulds - An innovative meth

Abstract Introduction: Neuroanatomy specimens like cerebrum, cerebellum, brain stem, etc. when taken out of preservation solution dries up and becomes discoloured within a short span of time. These specimens are easily damaged when used repeatedly and become unfit for teaching. The models of these specimen made with silicone using silicone moulds are similar to the original specimens with excellent surface detailing.Using silicone moulds, models like vertebrae using resin also can be made. Materials and methods : The silicone material used in our study is Moldsil P. For making a silicone mould, an acrylic jar is made, which is little bigger than the specimen. Moldsil P is mixed with hardner and poured into the container so that it fills half the volume of the jar. The specimen is immersed into the silicone in such a way that only its upper half is exposed. After the silicone is hardened, the rest of the specimen is covered with the silicone mixture [Moldsil P+hardener] and allowed to dry. The specimen is taken out and the cavity of the impression is filled with silicone or resin to make a cast. Results &amp; Conclusion: The silicone models of neuroanatomy specimens made using silicone moulds are soft, easy to handle and are exactly similar to the specimens. These are used as an alternative teaching aid. Silicone moulds can be used for taking resin cast of vertebra

Paleoneuroanatomy of the aetosaur Neoaetosauroides engaeus (Archosauria: Pseudosuchia) and its paleobiological implications among archosauriforms.

The paleoneuroanatomy of pseudosuchian archosaurs is poorly known, based on direct examination of the internal morphology of braincases and a few artificial endocasts. Among aetosaurs, only one endocast has been described almost a century ago by Case (1921) corresponding to Desmatosuchus spurensis from the Chinle Formation (Norian) of Texas, US, based on a resin cast. Here, we describe the first natural endocast of an aetosaur, Neoaetosauroides engaeus from the Los Colorados Formation (Norian) of NW Argentina, and also developed the first digital endocast of this taxon including the encephalon, cranial nerves, inner ear, and middle ear sinuses. The neuroanatomy of Neoaetosauroides engaeus exhibits several differences from that of Desmatosuchus spurensis despite their phylogenetic proximity, which may be a reflection of their different habits. The information provided by the endocasts of Neoaetosauroides engaeus about its olfactory region and the orientation of its head, based on the inclination of the inner ear, could support the proposal for an animalivorous diet, instead of an herbivorous one as in most aetosaurs. The new information here obtained contributes to the knowledge of the neuroanatomical diversity of archosauriforms and more specifically among pseudosuchians and their paleobiological roles in the Triassic continental communities.

A cell culture device equipped with a micro-needle electrode array fabricated using backside exposure mold and resin casting.

A cell culture device equipped with a micro-needle electrode array was fabricated for the signal analysis of cell spheroids, cell masses, and cell sheets. For the analysis, sharp needle electrodes with a high aspect ratio for facilitating easy penetration into the cell mass and a small pitch for fine spatial resolution were required. Microelectromechanical systems (MEMS) technology is one of the common solutions for the fabrication of devices. However, an additional process, such as anisotropic etching or electro-polishing, is required for fabricating sharp needles. Tapered needles were fabricated using backside exposure for coating a layer of thick resist film on a glass substrate. The incident beam from mask apertures were diffracted and attenuated in the medium, resulting in tapered intensity distribution. A needle-like shape was obtained after performing resist development without using additional MEMS process. In this study, the theoretical analysis of optical intensity distribution and design and fabrication process of the device were described. Finally, the effectiveness of the device was evaluated by adding cultured cell mass on the needle array. Signals with spikes and fluctuations were observed in the electrode covered with cell mass, whereas only noise was observed on the non-covered electrode, demonstrating the signal pick-up ability of the device during cell culture.

Raman spectroscopy as a powerful technique for the identification of polymers used in cast sculptures from museum collections

AbstractThe chemical identification of materials is the first step for developing and implementing recommendations for the care and display of resin cast and plastic objects in museum collections. This paper presents advantages as well as limitations of portable Raman. Therefore, a comparative analysis of portable and benchtop Raman instruments was performed in the study of materials found in the contemporary art collections of the National Museum in Krakow. The results of the Raman study were complemented with those obtained using Fourier transform infrared, near infra‐red, and gas chromatography mass spectrometry, in order to verify their accuracy. The results of this study showed that portable Raman spectroscopy is a suitable technique for the identification plastics in museum collections.

Prospects for Stellarators Based on Additive Manufacturing: Coil Frame Accuracy and Vacuum Vessels

High geometric complexity at high accuracy delays the construction of new stellarators and the related research. Thus, exploring whether additive manufacturing (AM) might provide advantages to the fabrication and design philosophy of stellarators appears valuable. Three coil frame supports were designed, produced by three AM techniques (SLA, FDM, and PolyJet) and measured by a Coordinate Measuring Machine. For FDM (similar to SLA), average of ±0.17% mean deviation was obtained and 68% of the points (one sigma) deviate less than ±0.28%. Three assays were performed for modular stellarator vacuum vessels: 1) a thin copper liner attached to a resin shell cast in an AM mold; 2) a thin electroformed liner for a test vacuum vessel; and 3) electrodeposited coating on an AM shell. The assays showed alternative 3) the simplest and fastest. The results from such studies and assays are reported and integrated with the previous results. Low stiffness and strength of AM plastics was previously tackled with fiber-reinforced resin cast in AM hollow structures (3Dformwork technique). Thus, AM, particularly combined with other fabrication methods, proved to be appropriate for the production of certain unpretentious small- and middle-size stellarators.

THE EFFECT OF DIFFERENT MODEL TECHNIQUES ON THE MARGINAL GAP OF IMPLANT SUPPORTED FIXED PARTIAL DENTURE

Statement of problem: The conventional model fabrication methods have multiple error-introducing steps such as impression, stone setting, waxing and casting; therefore a more reliable and quality controlled method of model fabrication is required Objective: This research was designed to evaluate the effect of different model fabrication techniques: Conventional stone cast, Rapid Prototyping-3D printing and CAD/CAM on the marginal gap of implant supported fixed partial denture. Materials and methods: An epoxy resin cast simulating a clinical case with missing lower first mandibular molar was fabricated that served as a master cast from which an optical impression was done to fabricate a 3D printed model and a milled model , and another rubber base impression was done to fabricate a conventional cast, upon these three casts, five three units bridge was fabricated on each model, then marginal gap of implant supported fixed partial denture was evaluated using stereomicroscope. Results: Two-way ANOVA revealed significant differences were found between the model manufacturing techniques. 3D-printing showed the lowest marginal gap value among all groups

Behavior of mandibular canines as abutment teeth and indirect retainers in Kennedy class II Removable Partial Denture Prosthesis

PurposeThe purpose of this study was to evaluate the behavior of mandibular canines acting as abutment teeth and indirect retainers of a Kennedy class II according to different designs: lingual rest and lingual rest associated with a reciprocal arm. Materials & methodsA resin cast with two simulated canine teeth was made in Ni-Cr alloy, representing a Kennedy class II mandibular arch. With the objective of simulating the resilience of the periodontal ligament, a polyurethane layer was added at the canine tooth's root. A metallic framework of Co-Cr alloy was fabricated with a T bar clasp and a lingual rest associated with a reciprocal arm. To obtain the second framework, the reciprocal arm was removed using a tungsten bur. Each framework was submitted to tensile force using a VersaTest machine. The magnitude and direction of canine movement during removal of the framework was measured using two dial gauges (mm). The axial tensile force required to remove the experimental framework (N) was also evaluated. The data were compared using the paired t-test with 95% confidence intervals. Differences were considered significant at P < .05. ResultsThe mean retentive force of the modified design framework with the reciprocal arm was significantly higher (P < .0001) than that of the framework with the lingual rest. The abutment teeth showed movement in the lingual and mesial directions, and this movement was less when associated with the reciprocal arm design. ConclusionThe reciprocal arm in association with a lingual rest in the framework decreased the movement of the abutment teeth when analyzed in the bucco-lingual and mesio-distal directions and contributed to increased retention by friction.

Mechanical Properties and Failure Analysis of Short Kenaf Fibre Reinforced Composites Processed by Resin Casting and Vacuum Infusion Methods

Modified and unmodified short kenaf fibre reinforced epoxy composites were processed with different short fibre lengths and fibre concentrations by resin casting (RC) and vacuum-assisted resin infusion (VARIM) methods. Three types of kenaf fibres were reinforced in epoxy polymer, namely, untreated kenaf fibre, mercerised and nanoclay-infused kenaf fibres. The mechanical properties such as tensile, flexural and impact properties of composites were studied. Nanoclay infused kenaf fibres have shown better tensile, flexural and impact properties than those of untreated and mercerised fibres. The composites processed by VARIM possess improved tensile and flexural properties when compared with RC composites, whereas the impact properties were better in RC composites than those of VARIM processed composites. The results showed that the mechanical properties of composites depend on the short fibre length and fibre concentration, irrespective of the processing conditions. Improved water barrier properties were also obtained in nanoclay-treated banana fibre composites.

Mudslide and/or animal attack are more plausible causes and circumstances of death for AL 288 ('Lucy'): A forensic anthropology analysis.

Following a global morphological and micro-CT scan examination of the original and cast of the skeleton of Australopithecus afarensis AL 288 ('Lucy'), Kappelman etal. have recently proposed a diagnosis of a fall from a significant height (a tree) as a cause of her death. According to topographical data from the discovery site, complete re-examination of a high-quality resin cast of the whole skeleton and forensic experience, we propose that the physical process of a vertical deceleration cannot be the only cause for her observed injuries. Two different factors were involved: rolling and multiple impacts in the context of a mudslide and an animal attack with bite marks, multi-focal fractures and violent movement of the body. It is important to consider a differential diagnosis of the observed fossil lesions because environmental factors should not be excluded in this ancient archaeological context as with any modern forensic anthropological case.

A comparative evaluation of the marginal adaptation of a thermoplastic resin, a light cured wax and an inlay casting wax on stone dies: An in vitro study.

Background:Different pattern materials do not produce copings with satisfactory, marginal accuracy when used on stone dies at varying time intervals.Purpose:The purpose of this study was to evaluate and compare the vertical marginal accuracy of patterns formed from three materials, namely, thermoplastic resin, light cured wax and inlay casting wax at three-time intervals of 1, 12, and 24 h.Methodology:A master die (zirconia abutment mimicking a prepared permanent maxillary central incisor) and metal sleeve (direct metal laser sintering crown #11) were fabricated. A total of 30 stone dies were obtained from the master die. Ten patterns were made each from the three materials and stored off the die at room temperature. The vertical marginal gaps were measured using digital microscope at 1, 12, and 24 h after reseating with gentle finger pressure.Results:The results revealed a significant statistical difference in the marginal adaptation of three materials at all the three-time intervals. Light cured wax was found to be most accurate at all time intervals, followed by thermoplastic resin and inlay casting wax. Furthermore, there was a significant difference between all pairs of materials. The change in vertical marginal gap from 1 to 24 h between thermoplastic resin and light cured wax was not statistically significant.Conclusion:The marginal adaptation of all the three materials used, was well within the acceptable range of 25–70 μm. The resin pattern materials studied revealed significantly less dimensional change than inlay casting wax on storage at 1, 12, and 24 h time intervals. They may be employed in situations where high precision and delayed investing is expected.

Synthesis of Branched Silicon-Containing Arylethyleneacetylene Resin and the Performance of Casting

With good thermal properties, dielectric property and high-temperature ceramics performance, silicon-containing arylacetylene resin (PSA) has opened an attractive alternative to high performance thermosetting resins in application in the area of aircraft and missile. However, it is difficult to introduce silicon into the main chain of organic arylacetylene. In this paper, branched silicon-containing arylethyleneacetylene (BSA) resin was synthesized by methyltrichlorosilane and diethynylbenzene with zinc powder as catalyst. The advantages lie in simple operation, short reaction period and mild heat release. BSA resin exhibits excellent processability with the processing temperature of 20?C - 150?C and processing window of 130?C. The glass transition temperature of the resin casting is over 500?C. The temperature of 5% weight loss (Td5) is up to 575?C and char yield of thermoset at 800?C (Y800) reaches 91% under nitrogen. Also, the dielectric constant and dielectric loss of casting has no change within 10 - 106 Hz.

Burrow Morphology of Alpheid Shrimps: Case Study of Alpheus brevicristatus and a Review of the Genus.

The Alpheus brevicristatus De Haan, 1844 is one of the commonest shrimp species inhabiting the tidal flats in Japan. This species is sometimes accompanied by the facultative symbiotic goby, Acentrogobius spp. Here, we investigated the burrow morphology of A. brevicristatus in a tidal flat of Uranouchi Inlet, Kochi Prefecture, Japan. We also reviewed existing literature on alpheid burrow morphology using the resin casting technique, to determine how burrows vary in the presence and absence of gobies. Nine burrows were casted in situ using polyester resin. All burrows were long, but shallow in structure, with several funnel-shaped openings and short cul-de-sac branches. This species appears to use several burrow openings to access the sediment surface for feeding with high efficiency. Gobies were not associated with all burrows cast; however, 1-3 individuals of the small alpheid shrimp Athanas japonicus Kubo, 1936 were entombed in seven of the casts. A review of 12 studies on the burrow morphology of 16 Alpheus species based on resin casting techniques showed wide variation in burrow characteristics, such as burrow depth, length, and number of openings. Our findings suggest that burrow structure is influenced by species-specific characteristics and sediment type. The possibility that the presence of the symbiotic goby affects the burrow morphology of Alpheus shrimp is discussed.

Thermo-mechanical behavior of TiO2 dispersed epoxy composites

To study the effect of particle size and filler concentration of TiO2 particles on the mechanical and viscoelastic properties (such as tensile strength, fracture toughness, storage modulus, damping properties and the glass transition temperature) of epoxy composites, tensile test with fractography, three point bend fracture test, DMA test were performed in accordance with the ASTM standards. The micron and nano-sized TiO2 particles were dispersed with loading fraction up to 8wt% in the epoxy resin. The result of tests revealed that epoxy resin cast filled with TiO2 particles represented higher tensile strength and fracture properties as compared to pristine epoxy. The maximum increase in tensile strength and fracture toughness for micron-sized TiO2 reinforced epoxy composites is 32.57% and 44.95% respectively at a filler loading of 4wt%. However, the maximum increase in tensile strength and fracture toughness for nano-sized TiO2 reinforced epoxy composites is 43.70% and 141.85% respectively at a filler loading of 6wt%. The storage modulus of reinforced epoxy composites in the glassy region showed maximum enhancement of about 4.73% for 4wt% micron-sized TiO2 and 32.88% for 4wt% nano-sized TiO2 as compared to pristine epoxy at 40°C.

Abstract 347: The Success of Humanizing Miniature Hearts is the Right Cannulation

The development of humanized miniature organs through decellularization of rodent organs and recellularization with human cells will provide higher quality translational evidence for in vitro models from animal to human within basic research and pharmacological applications. Here, we have focused on the preservation of the circulation network within rat hearts by cannulating the superior vena cava (SVC), ascending aorta (A), pulmonary vein (PV), and pulmonary artery (PA) (deemed 4-Flow). Compared to the conventional Langendorff, the 4-Flow cannulation is superior by allowing control of both atria and ventricles for non-invasive mechanical stimulation and most advantageous is access to both the coronary arteries and cardiac veins. Hence, the objectives are to thoroughly recellularize the heart and to conduct ventricular mechanical stimulation. Controlled perfusion was conducted with inflow via the SVC and A, and outflow via PV and PA. The resin cast of a decellularized heart in Figure 1A demonstrates that the retrograde flow in addition to antegrade flow through both coronary vascular networks permit efficient whole heart perfusion of solutions, cells, and factors. Multiphoton microscopy (1B) reveals that cells are perfused to capillaries and tissues but more so with enzymatic treatment (1C-D). All of the valves’ functionality are maintained, hence, mechanical stimulation of the left ventricle is possible via perfusion through the PV to expand the left chamber until the aortic valve opens to relieve the pressure (1E-F). Consequently, a 4-Flow humanized miniature heart is the complex in vitro model that will revolutionize the translation into patient studies.

Room temperature resin casting technique, a low cost and effective teaching tool in human anatomy

Objectives: To develop a cost effective optimal technique to preserve human tissues in a manner that detailed anatomy and almost all relevant properties are retained. Methods: The study was done in the department of Anatomy, Faculty of Medical Sciences, University of Sri Jayewardenepura. The tissues are initially preserved using formalin to stop the decaying since soft tissues are subjected to rapid decomposition. The water content is significantly removed using series of 99.9% pure acetone baths while maintaining the original tissue architecture. Dehydrated tissue part is embedded in a degassed clear liquid resin after mixing with the catalyst, which will polymerized into a solid resin cast. Results: In this invention, dehydrated human tissues, while preserving the original shape and volume are embedded in a clear synthetic resin cast. Follow up has been done over 3 years to date. No significance change has occurred in preserved specimens were observed. This is an appropriate method for preserving human body cross-sections at specific vertebral levels. The specimens are more durable than other specimen preservation methods used in Sri Lanka, tissue waste is minimum and there by the cost of preservation and maintenance of cadavers are reduced drastically. Currently these resin casts are used for teaching/learning activities in department of Aanatomy, FMS, USJP. Conclusions: Undoubtedly the detailed anatomy is best learned by cadaver dissections. But resin casting is a highly successful, cost effective supplementary method of teaching/learning gross and cross sectional Anatomy with no exposure to formalin.

Field survey and resin casting of Gymnogobius macrognathos spawning nests in the Tatara River, Fukuoka Prefecture, Japan

We investigated the spawning nests of Gymnogobius macrognathos on a tidal flat in the Tatara River, Fukuoka Prefecture, Japan. Digging uncovered 19 spawning nests. The number of eggs and the standard length of the guarding male were positively correlated. Nine spawning nests were examined using in situ resin casting. All casts had structures characteristic of callianassid shrimp burrows and were most likely those of Nihonotrypaea japonica. Spawning nests had significantly greater average diameters than shrimp burrow openings and may have been widened by G. macrognathos.

Characterization of hollow glass sphere reinforced epoxy composites: Dynamical mechanical analysis and morphology

Abstract Hollow glass spheres (HGS) have many application areas in the field of composite production due to their lightweight property together with having a sufficient strength. This study has the focus on adding the HGS to epoxy resin in different concentrations. The surface of the glass spheres were modified with silane prior to resin casting. The material characterization of the HGS filled epoxies was based on the silane presence and the HGS addition. Dynamic mechanical analysis was applied to observe the mechanical properties depending on the temperature of the composites. Morphological investigations were made to determine the interfacial adhesion between epoxy and the HGS. As a result of these, it was obtained that the HGS addition enhanced the stiffness of the material without a sharp reduction in the ductility. Silane was observed to be successful in improving the storage modulus below the glass transition temperature (Tg). However, the reduction in Tg was observed in high amount of modified HGS loading due to their interfering effect on the crosslink system of the epoxy.