Search

This article presents the findings of a study focusing on the gas generation of 3D-printed cores fabricated using binder-jetting technology with furfuryl resin. The research aimed to compare gas emission levels, where the volume generated during the thermal degradation of the binder significantly impacts the propensity for gaseous defects in foundries. The study also investigated the influence of the binder type (conventional vs. 3D-printed dedicated binder) and core construction (shell core) on the quantity of gaseous products from the BTEX group formed during the pouring of liquid foundry metal into the cores. The results revealed that the emitted gas volume during the thermal decomposition of the organic binder depended on the core sand components and binder type. Cores produced using conventional methods emitted the least gases due to lower binder content. Increasing Kaltharz U404 resin to 1.5 parts by weight resulted in a 37% rise in gas volume and 27% higher benzene emission. Adopting shell cores reduced gas volume by over 20% (retaining sand with hardener) and 30% (removing sand with hardener), presenting an eco-friendly solution with reduced benzene emissions and core production costs. Shell cores facilitated the quicker removal of gaseous binder decomposition products, reducing the likelihood of casting defects. The disparity in benzene emissions between 3D-printed and vibratory-mixed solid cores is attributed to the sample preparation process, wherein 3D printing ensured greater uniformity.

Casting cores produced in additive manufacturing are more often used in industrial practice, in particular in the case of the production of unit castings and castings with very complex geometry. The growing interest in the technology of 3D printing of cores and molds also brings emerging doubts related to their mechanical and technological properties. This article presents a comparison of the properties of cores made of sand with acid-curing furfuryl resin, made with 3D printing technology; the cores were prepared in a conventional way (mixing and compaction). The main purpose of this research was to determine the possibility of using shell cores as a substitute for solid cores, aimed at reducing the amount of binder in the core. The influence of the type of the binder and the size of the grain matrix fraction on the obtained mechanical and technological properties of the cores, with particular emphasis on abrasion and thermal deformation, as well as on the kinetics of their hardening, was demonstrated., Competing Interests: The authors declare no conflict of interest.

Purpose: The aim of this study is to present the results of treating the anterior segment of the eye with amnion membrane transplantation (AMT)., Materials and Methods: 16 patients were treated with amnion membrane transplantation because of: pemphigoid ocularis, combustio chaemica, ulcus corneae, keratopathia bullosa, descemetocele, symblepharon, graft disease. Histopathological investigations were performed by the use of impression cytology., Results: In 4 patients we obtained only temporary improvement. In 12 patients the treatment was successful with complete reepithelialization of the cornea and the conjunctiva. The impression cytology study showed an intensive regeneration of the corneal and conjunctival epithelium.

Unlabelled: The aim of this study was to examine the histopathologic picture of bulbar conjunctiva in glaucoma patients receiving topical antiglaucoma treatment., Material and Methods: Generally healthy patients with primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG) were included in our study. Conjunctiva specimens were obtained from the area of further fistula of 51 patients undergoing trabeculectomies and assessed by routine histopathological staining., Results: Non-specific inflammatory infiltration, thickening of the epithelium, decreased numbers of Goblet cells, proliferation of fibroblasts, collagen deposition and fibrosis were observed in the obtained material. Changes in cellular profile and in the extracellular composition of bulbar conjunctivas in patients receiving long-term topical antiglaucoma treatment were detected.

We report an exceptional case of ovarian leiomyoma in 73 years old patient. Leiomyoma of the ovary is a very rare tumor. Most cases are asymptomatic, this benign neoplasm is usually found incidentally on routine pelvic examination, at surgery or at autopsy. The available literature is reviewed. The possible histogenesis of ovarian leiomyoma was discussed.

The turbulent perinatal period in a neonate from a pregnancy with intrauterine death of one fetus is described. The live fetus was born in the 37th week of pregnancy after the macerated twin was delivered spontaneously. Convulsions, hypocalcemia, thrombocytopenia and enterocolitis necroticans were observed during the neonatal period.

In the work a case of an excessive functional activity of core of hyper suprarenal gland is presented. It is caused by atypical overgrowth of the left suprarenal gland. The cyst observed on the left kidney covering pathologically the changed suprarenal gland was an additional diagnostic difficulty.

The amount of lead pollution in the environment is increasing proportionally to the development of industry. Lead is capable of damaging the organism in many ways due to its high affinity to various tissues, different enzymes and serum proteins and its tendency to cumulate (1, 14). Acute lead poisoning occurs in people who have had intense, but short-term contact with organic lead compounds (tetraethylolead) used as an antidetonant in motor fuels, or plumbous orthoplumbate (red lead), which is an important component in anticorrosive paints (4, 6). Chronic poisoning by lead and lead salts, which used to occur in printers and workers in battery factories, is now a threat to the whole human population because of the hundreds of thousands of tons of tetraethylolead used as a fuel additive. This substance pollutes not only the atmosphere, but also the soil and the water and because of this, the food (10). The toxic effects of lead on the central and peripheral nervous system and the hematopoetic system is well known (9, 12), Less clear, however, are the toxic effects of this metal on the liver. As of now, there are still different views on the existence of negative effects of lead on the livers of people and animals exposed to this metal. Some researchers found no changes in the liver in cases of long-term contact with lead (3).

The rats were given potassium bichromate (K2Cr2O7) in dose of 2 and 5 mg/kg of body weight and magnesium chloride (MgCl2) in dose of 500 mg/kg for a period of 30 days. The two compounds were also given conjointly (K2Cr2O7-5 mg+MgCl2-500 mg). There were carried out histopathological as well as histochemical examinations of acid phosphatase activity, alkaline phosphatase activity and adenosine triphosphatase activity in the liver. With small doses (2 mg) of potassium bichromate no changes have been stated. With larger doses (5 mg) of potassium bichromate an increase of histochemical reaction to acid phosphatase as well as forming of histopathological changes such as parenchymatous degeneration, steatosis of hepatocytes and their necrobiosis have been observed. There has not been found any protective action of magnesium chloride on the cytotoxic activity of potassium bichromate on the liver cell.

Male rats were administered, for the period of 30 days, potassium dichromate (K2Cr2O7) in a dose of 2 and 5 mg/kg of body weight and magnesium chloride (Mg Cl2) in a dose of 500 mg/kg of body weight. These two substances were also administered jointly (K2C2O7-5 mg/kg and MgCl2-500 mg/kg of body weight). In the testicles of animals receiving K2Cr2O7 in a dose of 5 mg/kg of body weight in groups III and IV there were observed changes of significant degree, mainly degenerative and multifocal, which consisted in degenerative changes of various degrees and changes of necrotic epithelium cells which, in turn, consist in cell hyper- or hypochromasia of chromatolysis or pycnosis and, too, in lesions of testicle epithelium of the spermatic epithelium cells. The cells of the Leydig intraparenchymatous gland did not reveal any histopathological changes as well as changes in the increase of hyatochemical tests. The highest concentration of chrome was in the hair of the animals receiving K2Cr2O7 in a dose of 5 mg/kg of body weight.

Cobalt alloys produced in Poland and meant for orthopedic implants were morphologically and toxicologically evaluated. They were implanted subcutaneously in the para-osseous region of rats' heads. The results of the experimental tests strongly suggest the advisability of a clinical research project (study) on the examined cobalt alloys: Medpol-1 and Medpol-2.

A case report on an anencephalus with numerous heterotopias of brain tissue in the lungs is presented. The presumable period of development and other embryological aspect of this exceptional malformation are discussed.