Wax Models Research Articles

A Helmet of the Archaic Period in the Krasnodar Museum – Problems of Attribution

In 2020, an illicitly excavated bronze helmet confiscated by the FSB was brought to the Krasnodar Felitsyn State Historical and Archaeological Museum-Reserve. The helmet was assembled from two parts and embellished with engraved geometric and zoomorphic designs. The upper section is marked with a finial crafted from a wax model in shape of the head of a bird of prey. Two other helmets of this type are currently known, both from archaeological complexes: one from the village of Kholodny Rodnik near Tuapse (discovered in 2012), the other from the megalithic burial “Krinitsa-I” (2018 excavations). An analysis of the items found with these helmets allows us to date all three helmets to the 6th century BCE. The Krasnodar helmet is the more elaborately decorated of the three, with geometric ornaments analogous to those on Colchian-Koban bronzes of this period and zoomorphic designs imitating the Scythian Animal Style. All this gives reason to suggest this series of helmets to have been produced on commission for the warrior elite of the Northwestern Caucasus in the workshops of the Central Caucasus, which traditionally produced bronze table wares. The Krasnodar helmet is probably the earliest in this group. A rudimentary rim encircles the entire calotte – a feature going back to cast helmets of the Kuban type. The Krasnodar helmet can be dated to the end of the 7th – first half of the 6th centuries BCE.

A method of hollowing the obturator prosthesis and an overview on the pros and cons of the various materials used for hollowing.

Prosthetic rehabilitation of a partial or total maxillectomy with an obturator is the most acceptable treatment option. The hollowing of the obturator prosthesis is beneficial as it reduces the stresses over the underlying and surrounding tissues. A simple technique of fabricating a hollow bulb obturator has been discussed in this article. At the step of the packing of a denture, the hollow wax pattern of the defect area is formed with modeling wax. This hollow wax pattern is filled with water and is allowed to freeze to form an ice block. This ice block is removed from the wax pattern and is interposed between two layers for heat-cured acrylic resin and is then cured. After processing the denture, the water is retrieved by making a small hole in denture base, which is packed after hollowing with a cold cure acrylic resin. A lightweight prosthesis with a uniform thickness was achieved with a readily available and easily retrievable material, i.e., ice.

Measurement of Peri-Implant Bone Width with and without Metal Artifact Reduction Algorithm Using Two Cone-Beam Computed Tomography Software Programs

Objective: To assess the effect of metal artifact reduction (MAR) algorithm of two cone-beam computed tomography (CBCT) software programs on the accuracy of peri-implant bone width measurements . Material and Methods: This in vitro study evaluated 35 bovine rib bone blocks measuring 8 x 8 x 11 mm. Titanium implants were inserted in bone blocks and placed in a wax model of mandible. CBCT scans were obtained with ProMax 3D and Cranex 3D CBCT systems with and without the MAR algorithm. The width of buccal and lingual bone plates surrounding the implant was measured on CBCT scans by two observers. The Cronbach’s alpha was calculated to assess inter-observer agreement. The area under the curve (AUC), sensitivity and specificity values were calculated and compared. Results: The two observers had an excellent agreement. The accuracy of Cranex 3D was higher than that of ProMax 3D (p<0.05). Both CBCT systems showed higher accuracy when the MAR algorithm was not used (p<0.05). Both CBCT systems showed higher accuracy for measuring the width of the lingual plate than buccal plate (p<0.05) . Conclusion: The application of MAR algorithm did not notably increase the measurement accuracy in any CBCT system. Cranex 3D showed generally higher measurement accuracy than ProMax 3D.

Procesado térmico de moldes confeccionados con revestimiento de joyería mediante microondas por calentamiento híbrido

This research aims to contribute to the understanding and control of the processing of materials involved in artistic casting by microwaves, in order to facilitate this type of energy sources in the thermal processes of dewaxing. Specifically, the behavior of small samples made with commercial refractory coatings on simple wax models was studied. An adaptation and compatibilization of the conventional technique of fused jewelry was designed to validate an integral treatment with this energy alternative. On the one hand, a suitable time/power curve was designed for the initial dewaxing and drying of these pastes, taking into account the dielectric properties of the water present in their confection. On the other hand, a feasible procedure was studied for the development of their burning, through the use of hybrid heating using silicon carbide (SiC-β) as a susceptor. In order to apply a step temperature, a double muffle combining transparent and absorbing materials with the capacity to reach 750°C with MW power of 700w was fabricated. The results obtained intensified the interest in studying a thermal processing for the dewaxing and firing of refractory linings with larger models and more complex shapes oriented to jewelry and small format sculpture.

Features of Use of Rapid Prototyping Technology in the Manufacture of Wax Models of GTE Turbine Blades

The paper presents the main results related to the peculiarities of using 3D printing technology and methods of rapid prototyping in the manufacture of wax models of blades of a GTE turbine. The main design solutions that must be used in the design of a blade blank are presented in detail: the total shrinkage coefficient, equidistant rolling of the airfoil profile, allowance along tract surfaces, radial fillets, and a number of others. The results of control of geometric dimensions of the turbine blade blanks at the corresponding stages of the technological process showed deviations from the nominal value within the tolerance range for the executable dimensions, and the statistical information from the measurement of an experimental batch of wax models of blade blanks showed stability of the silicone tooling and ability to manufacture a series of wax models of the blades in the amount of 100 pieces when using one mold.

An Analysis of the Casting Polymer Mold Wear Manufactured Using PolyJet Method Based on the Measurement of the Surface Topography.

An important factor having an impact on the condition of machine parts is their surface topography. For instance, in the production of a molded element in casting or injection molding processes, the surface topography of the molding cavity has a significant impact on the surface condition of the product. An analysis of the wear of a mold made with the PolyJet technique was performed in this work, and we examined the surface topography using the stylus method after casting a wax model of the turbine blade. The surface topographies showed a gradual degradation of the mold cavity surface. After the manufacture of 40 castings, there was a significant deformation of the microstructure of the mold cavity. The maximum height value (Sz) parameter had the most dynamic change from 18.980 to 27.920 μm. Its growth dynamics are mainly influenced by maximum peak height (Sp) rather than the maximum pit height (Sv) parameter. In the case of the root mean square height (Sq) and arithmetic mean height (Sa), their gradual increases can be seen from 2.578 to 3.599 μm and from 2.038 to 2.746 μm. In the case of the value of the skewness (Ssk) parameter, a small positive skew was observed. As for the kurtosis (Sku) values, the distributions are clearly leptokurtic.

Cosimo’s Genius and Ammannati’s Ingenium: The Wax Model for the Genio Mediceo

In 2018 the Rijksmuseum acquired the wax modello for the Genio Mediceo (‘Genius of the Medici’), a bronze fountain statue that was made around 1557 in Florence by Bartolomeo Ammannati for the Duke of Tuscany, Cosimo I de’ Medici. It is Ammannati’s only known undisputed wax model. The attribution is confirmed by a reference to the statue in four sonnets by the lawyer Lelio Bonsi – published in 1560 by Ammannati’s wife, Laura Battiferra. The Genio Mediceo, a naked youth holding a Capricorn and a sphere – representing the cosmos (‘cosmo’, as an allusion to Cosimo) – represents the personal protector (genius) of the Medici ruler, and harks back to a concept from Classical Antiquity. Cosimo modelled his image on the Roman emperor Augustus, the supposed founder of Florence, and also adopted his genius cult and star sign of Capricorn. As the symbolic link between the heavens and the earth, Ammannati’s Genio watched over Cosimo’s fate, which was determined by the stars, and embodied the motto of this ‘new Augustus’: fiducia fati (‘trust in fate’). The Genio fountain was designed for Cosimo’s private apartments in Palazzo Vecchio and can be seen as the ‘male counterpart’ of the marble Juno fountain that Ammannati made for the Sala Grande in that palazzo: in Antiquity, the juno was the female version of the genius. The Juno fountain was associated with Cosimo’s wife, Eleonora of Toledo.

Study of FDM technology applications in the casting production of GTE details

FDM is an additive manufacturing technology that can be effectively used to make investment casting models. This method is considered economical in a single production, since it does not require the manufacturing of expensive equipment. However, the roughness of models surface made by FDM printing is significantly lower than wax models obtained by traditional way - using metal and elastic silicone molds, that ultimately affects the roughness of castings. In this work, was studied the use of FDM printing technology for materials: REC CAST, PVA and Wax3D from company the “Filamentarno!”, used in molds to obtain models, as well as a combined method for wax models production. FDM printing technology is especially suitable for producing models with internal channels and cavities through the use of water-soluble support materials.

Influence of wet foam stability on the microstructure of ceramic shell foams

In this study, recycled ceramic shell particles from the mold used in precision casting, which consists of coating a wax model with several layers (shell) of mullite and zirconia particles of different sizes, were used as raw material to prepare stable wet-foams by direct foaming and gelcasting using ovalbumin. The control of suspension parameters, such as pH, dispersant concentration, solids concentration and stirring velocity, can influence the foam stability against destabilization mechanisms (such as drainage, coalescence, and Ostwald ripening), optimizing the final properties of the cellular ceramic structures. The rheological behavior of suspensions and the gel point temperature of foams was also evaluated. The evolution of the bubbles-sizes (as a function of time) into the wet foam structure was analyzed by Axio Vision LE and ImageJ software. The fired ceramic shell foam (1550 ​°C, 2 ​°C/min, for 2 ​h) exhibited porosities higher than 80%, characterized by a highly interconnected network of spherical pores, with sizes ranging from 518 ​± ​29 to 1088 ​± ​103 ​μm and compressive strength of 0.9 ​± ​0.2 ​MPa. The morphological features and mechanical strength of the obtained foam indicating the possibility that it could be employed as low-cost replacement for radiant porous burners applications.

Naḫıls and Candy Gardens in the 1720 Ottoman Imperial Festival

Abstract In late July 1720 Sultan Ahmed III (r. 1703–30) and his high-ranking officials decided to host a circumcision festival in Istanbul that would start in mid-September and continue for three weeks. As noted in the narrative sources, among various other preparations that the officials had to take care of, the most urgent task was to construct large and small naḫıls (lit. “date palms”), consisting of wooden poles decorated with wax, fruit, flowers; and giant model candy gardens (sing. bāġçe-i şeker). Despite this concern, the sources do not provide substantial information regarding the construction of these objects. Interestingly, this lack of information is also evident in narrative sources related to previous imperial celebrations. By analyzing unknown archival documents and considering the textual and pictorial sources for the 1720 festival, this essay intends to elucidate the design and construction process of the splendid naḫıls and candy gardens, which were indispensable material objects in Ottoman imperial festivals.

Effect of different doses of radiation on morphogical, mechanical and chemical properties of primary and permanent teeth\u2014an in vitro study

BackgroundRadiotherapy, applied to the head and neck region, can cause radiation side effects such as reduction of saliva and radiation caries. The aim of this study was to perform an in vitro assessment of the effects of radiation therapy on the morphological, mechanical, and chemical properties of primary and permanent teeth.MethodsOne hundred four extracted human teeth (52 impacted wisdom teeth, 52 primary molar teeth) were used. The teeth were divided into two parts in the mesiodistal direction. Of the 98 teeth, the vestibular sections were used for the vickers analysis and lingual sections were used for the Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysis. The teeth in the experimental group were fixed to wax models. Each model had an equal number of teeth (n = 7). The doses were applied to the teeth for 6 weeks; 5 week days and 2Gy daily. After the radiotherapy was conducted weekly, a wax model was taken from radiation reception. Along with the elemental contents (Na, K, Mg, P, and Ca) of the teeth, enamel and dentin microhardness was evaluated, and SEM analyzes were performed on 6 teeth.ResultsRadiation caused a decrease in microhardness of enamel and dentin (p < 0.05). In the elemental analysis by ICP-OES, it was observed that there were decreases in all elements after 60Gy compared to the control group (p < 0.05). In the experimental groups, amorphous structures were encountered in SEM images.ConclusionsRadiation has negative effects on the teeth structure and additional studies are needed in this regard. This study indicates that radiotherapy patients are at a higher risk for dental caries.

Study of the stability of the geometric dimensions of wax models of GTE blades using rapid prototyping technology

The work presents the results of a study of the stability of geometric dimensions of wax models of compressor stator blades of the 15th stage, manufactured using rapid prototyping technology. In the process of performing the work, the algorithm for assigning the total shrinkage was studied. It is established that the deviation of geometric dimensions, both in the greater and in the lesser direction relative to the nominal size of the blade is caused by the amount of volumetric shrinkage of the material used. Measuring the linear dimensions of wax models of blades allowed us to determine the nature of the geometry deviation for further accounting and compensation.

Role of dodecane on coal particle-bubble interaction in aqueous phase

Even if coal particles are hydrophobic, interaction between these particles and air bubbles can be enhanced by nonpolar oil in froth flotation. The role of a nonpolar liquid dodecane on coal particle-bubble interaction in aqueous phase was investigated and compared to that of a solid analogue, paraffin wax via a combined application of water contact angle and particle-bubble stability measurements, and molecular dynamics simulations. It was found both dodecane and paraffin wax can increase hydrophobicity of coal surface and attachment stability of coal particle-bubble aggregates when they covered the coal particles. Despite similar chemical structure and hydrophobicity, dodecane was more effective than paraffin wax. Molecular simulations confirmed that, comparing to the unmodified coal particle, both dodecane and paraffin wax models could increase the attachment strength of coal particle. However, different from immobile solid paraffin wax, we demonstrated that the liquid like properties of the dodecane layers present on the coal particle surfaces play an essential role in the particle-bubble interaction. When the coal particle covered by dodecane arrived at gas−water interface, the dodecane molecules will migrate and rearrange to form a new film at this interface. In addition to hydrophobic attraction of the gas bubble, the dodecane film will provide additional adhesion towards the coal particle due to oleophilicity of the coal particle, enhancing the stability of bubble-particle aggregate.

Characterization of histomorphological and microbiological changes in tooth pulp to assess post-mortem interval: an observational study

BackgroundThe rate of decomposition of the organs of the body has been widely studied by forensic pathology experts for the determination of time elapsed after death. But researches pertaining to the dental pulp organ have been very sparse. This study attempts to identify the morphologic and microscopic characteristics of the tooth pulp for over a time period of 2 years with respect to time elapsed since its designated death.Materials and methodEight experimental groups consisting of 5 extracted teeth in each group were constituted. The apical foramen was blocked with modeling wax. In groups 1, 2, 3, 4, 5, 6, 7, and 8, dental pulp was extirpated after 24 h, 48 h, 72 h, 1 month, 3 months, 6 months, 1 year, and 2 years of extraction, respectively. The pulp tissue underwent a standard histological processing and hematoxylin and eosin (H & E) staining. Slides were observed under a light microscope.Results and discussionsMorphologically, the color of the pulp changed from pink at 24 h to pale pink by 72 h. The consistency ranged from soft to firm to jelly by 72 h and later became desiccated and friable by 2 years. Microscopically, a rapid degeneration in the constituents of pulp was seen until 72 h followed by slowing down beyond 1 month with less histologic variations. Smaller vacuolations were observed in a 24-h PMI pulp which progressively increased filling up the entire stroma by 2 years. The nuclei underwent a series of autolytic changes with increasing time. The odontoblastic layer was seen in some areas for up to 6 months. Microbiological assessment showed Gram-positive staphylococci and streptococci up to 2 yearsConclusionEstimation of post-mortem interval (PMI) changes in pulp, which is enclosed in a hard structure, composed of enamel and dentin provides the advantage of being studied up to 2 years as compared to other organs. Progressive degradation of the matrix and cellular constituents of the pulp with increased vacuolations were noted in our study, and evaluation of these characteristics can be a cost-effective and simplified additional tool to estimate the PMI.

Study on the fabricated feasibility of electrodes in EDM using rapid prototyping (RP) and investment casting technology

This study fabricates a roughing electrode of electrical discharge machining (EDM) using a rapid prototyping (RP) system and investment casting technology, which reduces the overall time that is required for fabrication and the cost of the manufacturing process for a selected electrode. Pro/E (3D CAD) software is used to design the electrode prototype, which has a complex appearance, and to transform the CAD model into stereolithography (STL) format. An RP machine (Zcorp 402 3DP) is used to construct a gypsum-based powder model. After a sealing process using the permeation of resin, the water resistance and strength of the gypsum-based material are increased. The manufacturing process then involves creating a wax model with a gypsum electrode that is strengthened by resin permeation by casting a vulcanized silicone molding. The brass electrode is fabricated using investment casting technology. The results of an EDM test show that the brass electrodes with RP that are manufactured perform well and the total time that is required to machine the EDM electrode using RP is 15.8% less than the time that is required for a CNC machining process.

Wax models in dermatology: Updated through 2020

Wax models have occupied a unique position in the teaching of dermatology. The wax model offers a unique presentation of the morphology, often not captured by other methods. Much has already been written about the unfortunate fate of many of these collections. Some models went to historical collections, a few were saved to continue their didactic purpose, and still others met their untimely demise. There has been renewed interest in the preservation of these models in recent years, from dermatologists and historians alike, and this has led to increasing efforts to document the origin, migration, exhibition, and maintenance of these collections. Our mission for this study is to report on our findings of the existence and whereabouts of dermatologic wax models since the 1990 survey. Even with the advent of the Internet and interest generated for preserving these wonderful illustrations of dermatologic conditions, many collections have remained unknown or dismantled. In the end, wax models have survived the introduction of hand-colored artist’s renditions, color photography, and even computerized illustrations. Although no longer the premier teaching tool of yesteryear, their survival reflects upon the development of dermatology and the initial transition from hand-colored prints to our current digital-oriented age.

The use of 3D printing technology in the creation of patient-specific facial prostheses

Personalised medicine aims to optimise patient outcomes by tailoring treatments and interventions to the individual. While this approach can offer a number of benefits, it can be accompanied by significant overheads in terms of resources. Prostheses exist in order to restore and replicate the normal functions and appearance of the body but if these are not individually tailored to the patient's needs then a true restoration cannot be fully achieved. Traditionally a labour intensive process, the fabrication of craniofacial prostheses, involves taking a plaster cast of the area to be treated, hand carving wax models of the restoration and multiple meetings with the patient to alter this wax restoration before making a final prosthesis in silicone. Utilising the patient's pre-existing computed tomography (CT) images and 3D printing technology, a patient-specific prosthesis can be created with improved efficiency and accuracy. This study demonstrates methods used to create a patient-specific orbital prosthesis using CT images. These images were manipulated in a way which allowed for the intact orbit to be mirrored and used to develop a 3D printed model which acted as the starting point to create a silicone prosthesis. The benefits of using this method include reduced manufacturing time, decreased outpatient appointments, improved personalised outcomes and a repeatable process allowing multiple prostheses to be made. 3D printing is a valuable tool which can provide significant savings in time and improve patient outcomes by offering a tailored approach to each individual's treatment.

Advances and Future Challenges of Wax Removal in Pipeline Pigging Operations on Crude Oil Transportation Systems

Wax deposition is a severe flow assurance challenge that threatens waxy crude oil production and transportation. For wax remediation, pipeline pigging is the most widely used technique. However, the elusiveness of wax removal mechanism and the lack of reliable methods to evaluate wax breaking force and wax removal efficiency easily trigger pig stalling and wax blockage in field pigging operations. Modeling wax breaking force and wax removal efficiency, therefore, promotes the pigging confidence. This Review seeks to clarify the current picture of wax removal research in crude oil pipeline pigging. Relevant wax deposit properties including wax layer thickness and strength are discussed. Wax removal mechanisms are summarized from perspectives of wax–pig interaction, macroscopic force response, and scenarios with oil flow. Prediction models of wax breaking force and wax removal efficiency are analyzed comprehensively. Pig geometry optimization using this model is given. In addition, the key roles of wax deposit strength, viscoelasticity and thixotropy, foam pig investigation, and wax plug prediction are highlighted for guiding future endeavors in this area.

FREQUENCY OF INADEQUATE DIMENSIONS OF OCCLUSAL REST SEAT PREPARED ON 2ND MOLAR ABUTMENTS FOR CAST REMOVABLE PARTIAL DENTURES

Objective: To evaluate occlusal rest seat preparations for cobalt chromium cast removable partial denture. Materials and Methods: A cross-sectional study was carried out in the department of Prosthodontics, Khyber College of Dentistry, Peshawar starting from June 2014 to June 2015 using consecutive non-probability sampling technique. Data was collected from 127 partially dentate patients having a bounded saddle with a distal abutment as second molar with normal occlusal surface morphology and mesio-occlusal rest seats prepared on the mentioned molar teeth. Patients having partially dentate areas with no principal abutment as second molar and rest seat other than mesio-occlusal rest seat were excluded from the study. Casts were evaluated for aspects of rest seat like the general outline form of the rest seat (visually assessed from the casts), the bucco-lingual and mesio-distal dimensions were measured using a divider and scale. Depth of the rest seat was measured by placing a piece of warm modelling wax with the casts in occlusion and measuring the thickness using Iwenson gauge. Data was analyzed using SPSS 20. Results: Out of 127 patients, mean age recorded was 38 years with Standard deviation ± 2.15. Males (62%, n=79) reported more than females (38%, n=48). The most frequently reported inadequate dimension was the depth of rest seat (46%, n=58), followed by the general outline form and mesio-distal width (40%, n= 51). The bucco-lingual dimension was recorded to be inadequate in 37% (n=47) of the cases. Conclusion: Most of The participants tend to under-prepare rest seat in terms of outline form, width, length and depth.

Fabrication of Microfluidic Chips Based on an EHD-Assisted Direct Printing Method.

Microfluidic chips have been widely used in many areas such as biology, environmental monitoring, and micromixing. With the increasing popularity and complexity of microfluidic systems, rapid and convenient approaches for fabricating microfluidic chips are necessary. In this study, a method based on EHD (electrohydrodynamic)-assisted direct printing is proposed. Firstly, the principle of EHD-assisted direct printing was analyzed. The influence of the operating voltage and moving speed of the work table on the width of a paraffin wax model was studied. Then, two kinds of paraffin wax molds for micromixing with channel widths of 120 μm were prepared. A polydimethylsiloxane (PDMS) micromixer was fabricated by replicating the paraffin wax mold, and the micromixing of blue and yellow dye was realized. The results show that EHD-assisted direct printing can be used to make complex microscale structures, which has the potential to greatly simplify the manufacturing process.