Additive Manufacturing as a Solution to Challenges Associated with Heat Pipe Production

The aim of this review is to present the recent developments in heat pipe production, which respond to the current technical problems related to the wide implementation of this technology. A novel approach in HP manufacturing is to utilise hi-tech additive manufacturing techniques where the most complicated geometries are fabricated layer-by-layer directly from a digital file. This technology might be a solution to various challenges that exist in HP production, i.e., (1) manufacturing of complex or unusual geometries HPs; (2) manufacturing complicated and efficient homogenous wick structures with desired porosity, uniform pore sizes, permeability, thickness and where the pores are evenly distributed; (3) manufacturing a gravity friendly wick structures; (4) high customisation and production time; (5) high costs; (6) difficulties in the integration of the HP into a unit chassis that enables direct thermal management of heated element and decrease its total thermal resistance; (7) high weight and material use of the part; (8) difficulties in sealing; (9) deformation of the flat shape HPs caused by the high pressure and uneven distribution of stress in the casing, among others.     

The Accelerated Aging Impact on Mechanical and Thermal Properties of Polypropylene Composites with Sedimentary Rock Opoka-Hybrid Natural Filler

This paper presents the impact of accelerated aging on selected mechanical and thermal properties of isotactic polypropylene (iPP) composites filled with sedimentary hybrid natural filler-Opoka rock. The filler was used in two forms: an industrial raw material originating as a subsieve fraction natural material, and a rock calcinated at 1000 °C for production of phosphorous sorbents. Fillers were incorporated with constant amount of 5 wt % of the resulting composite, and the material was subjected to accelerated weathering tests with different exposition times. The neat polypropylene and composites with calcium carbonate as a reference filler material were used for comparison. The aim of the research was to determine the possibility of using the Opoka rock as a new hybrid filler for polypropylene, which could be an alternative to the widely used calcium carbonate and silica. The thermal, mechanical, and structural properties were evaluated by means of differential scanning calorimetry (DSC), tensile tests, scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy with attenuated total reflectance (FTIR/ATR) prior to and after accelerated aging. As a result, it was found that the composites of polypropylene with Opoka were characterized by similar or higher functional properties and higher resistance to photodegradation compared to composites with conventional calcium carbonate. The results of measurements of mechanical properties, structural and surface changes, and the carbonyl index as a function of accelerated aging proved that Opoka was an effective ultraviolet (UV) stabilizer, significantly exceeding the reference calcium carbonate in this respect. The new hybrid filler of natural origin in the form of Opoka can therefore be used not only as a typical powder filler, but above all as a UV blocker/stabilizer, thus extending the life of polypropylene composites, especially for outdoor applications.     

Comparison of Numerical Simulation Techniques of Ballistic Ceramics under Projectile Impact Conditions

This article presents an analysis of the effectiveness of available numerical techniques in mapping the characteristic behavior of ballistic ceramics under projectile impact conditions. As part of the work, the ballistic tests were performed on the layered ceramic/steel composite armor and tested with the 7.62 × 39 mm, armor-piercing incendiary (API) BZ projectile. The experimental tests were then mapped using computer simulations. In numerical analyses, four different techniques were used to describe cubic ceramic tiles Al₂O₃ placed on the ARMOX 500T steel backing plate, i.e.,: the Finite Element Method without Erosion (FEM), Finite Element with erosion (FEM + Erosion), Smoothed Particles Hydrodynamics (SPH) and a hybrid method that converts finite elements to SPH particles after exceeding the defined failure criteria (FEM to SPH conversion). The effectiveness of the individual methods was compared in terms of quality (mapping of characteristic phenomena occurring during the penetration process), quantity (bulge height of the backing plate) and time needed to complete the calculations. On the basis of the results of the experiments and numerical simulations, it was noticed that the most accurate reproduction of the phenomenon of ballistic impact of AP projectiles on ceramic/steel composite armor can be obtained by using a hybrid method, incorporating the conversion of finite elements into SPH particles. This method should be used in cases where accuracy of the results is more important than the time required to complete the calculations. In other situations where the purpose of the calculation is not to determine, for example, the exact value of penetration depth but only to observe a certain trend, the FEM method with defined erosion criteria (variant 2), which is more than 10 times faster, can be successfully used.     

Influence of Laser Beam Power on Microstructure and Microhardness of Fe/ZrC Coatings Produced on Steel Using Laser Processing—Preliminary Study on the Single Laser Tracks

This paper presents preliminary tests of the parameter analysis of the Fe/ZrC coatings production process and the obtained properties. The effects of laser beam power on the obtained microstructure, chemical composition and microhardness were investigated. The tests consisted of the production of composite coatings by laser processing of initial coatings made in the form of a paste on a steel substrate. During the tests, a diode laser with a rated power of 3 kW was used. The laser processing process was carried out using a constant scanning speed laser beam of 3 m/min and four different powers of the laser beam: 500 W, 700 W, 900 W, 1100 W. It was found that it is possible to create composite coatings on a steel surface, where the matrix is made of iron-based alloy and the reinforcing phase is ZrC carbide. It was also found that reinforcing phase content decreased as laser beam power increased. A similar relationship was found for microhardness. As laser beam power increases, the microhardness of the iron-based matrix decreases, finally reaching a value lower than the heat-affected zone. It was found that the amount of hard carbide phases in the iron-based matrix affects the total hardness of the coatings. Presented study concern Fe/ZrC coatings that have not previously been produced on steel by laser processing of precoating, which may be a new contribution in the field of metal surface engineering.     

Synthesis of Hydroxyapatite/Iron Oxide Composite and Comparison of Selected Structural,Surface, and Electrochemical Properties

The paper presents the synthesis of a hydroxyapatite/iron oxide composite utilizing the wet chemical method, as well as the comparison of several selected material characteristics. As follows from the literature reports, hydroxyapatite is a common mineral possessing numerous significant properties. Nowadays, there is an increase in the amount of research on possible modifications of this compound. The promising way to improve hydroxyapatite features is its combination with iron oxide. Particularly, there can be two forms that are distinguished, namely Fe₃O₄ and γ-Fe₂O₃. These oxides exhibit valuable properties, particularly magnetism. A combination of the mentioned materials leads to multifunctional composite formation with many potential applications, as follows from several studies. However, this area of science is not fully developed. There are still many aspects to be examined. The synthesized composite and its components were analyzed by employing the following methods. The X-ray diffraction analysis revealed formation of hydroxyapatite and Fe₂O₃ crystalline phases. Moreover, porosimetry proved a larger specific area for the composite sample in comparison with other materials. The results obtained using the SEM method confirmed an external layer of hydroxyapatite and spherical shapes of internal Fe₂O₃ particles. Furthermore, the X-ray photoelectron spectroscopy data presented characteristic peaks of Fe, Ca, P, and O atoms in all samples. The Fourier Transform Infrared spectra displayed all the specific vibrations typical of the analyzed materials. What is more, the Vibrating Sample Magnetometer method confirmed the paramagnetic nature of the samples. It could be concluded that the synthesized composite has intermediate properties between the components used in the formation process. The results suggest that these composites are superparamagnetic. This type of material architecture would be well suited for biomedical applications.     

Therapeutic approach to pediatric acute mastoiditis – an update

IntroductionAcute mastoiditis remains the most common complication of acute otitis media. It may rarely appear also in cochlear implant patients. However, the treatment recommendations for this disease are not precisely defined or employed, and in the current literature the differences regarding both the diagnosis and management are relatively substantial.ObjectiveThe aim of this study was to determine a standard and safe procedure to be applied in case of pediatric acute mastoiditis.MethodsA retrospective chart review of 73 patients with 83 episodes of acute mastoiditis hospitalized at our tertiary-care center between 2001 and 2016 was conducted. Bacteriology, methods of treatment, hospital course, complications, and otologic history were analyzed. Based on our experience and literature data, a protocol was established in order to standardize management of pediatric acute mastoiditis.ResultsAll the patients treated for acute mastoiditis were submitted to an intravenous antibiotic regimen. In the analyzed group pharmacological treatment only was applied in 11% of children, in 12% myringotomy/tympanostomy was added, and in the vast majority of patients (77%) mastoidectomy was performed. In our study recurrent mastoiditis was noted in 8% of the patients. We also experienced acute mastoiditis in a cochlear implant child, and in this case, a minimal surgical procedure, in order to protect the device, was recommended.ConclusionsThe main points of the management protocol are: initiate a broad-spectrum intravenous antibiotic treatment; mastoidectomy should be performed if the infection fails to be controlled after 48 h of administering intravenous antibiotic therapy. We believe that early mastoidectomy prevents serious complications, and our initial observation is that by performing broad mastoidectomy with posterior attic and facial recess exposure, recurrence of acute mastoiditis can be prevented.     

The course of pregnancy and delivery in women after genetic amniocentesis before and after 35 years of age

OBJECTIVES: The demand for genetic amniocentesis in case of young pregnant women has significantly increased due to various new indications. Moreover, nowadays a growing number of women aged > or =35, who required genetic amniocentesis, get pregnant The aim of the following study has been to compare the course of the pregnancy, the delivery and the condition of the newborn in two groups of patients: 18-34 years old and > or =35 years old. MATERIAL AND METHODS: 783 women underwent the procedure of amniocentesis at the Department of Obstetrics of Medical University of Gdansk in 1996-2003. A group of 540 women, who answered the questionnaire about the course of the pregnancy and the delivery after the procedure, has been isolated. RESULTS: Fetal loss occurred in 2 cases (1.6%) in the group of the younger women and in 8 cases (0.8%) in the group of > or =35 year-olds (p=0.84). There was no statistically significant difference between younger and older patients when comparing complications after the procedure in the first three weeks following amniocentesis: spotting, bleeding, leakage of amniotic fluid. Frequency of late complications such as gestational diabetes mellitus, pregnancy induced hypertension and urinary tract infections were comparable in both age groups women. Cesarean section has been more frequently performed in case of the older women than in the group of younger patients, with statistical difference p=0.003. In most cases (33.9%) it has been an elective cesarean section, performed due to advanced maternal age rather than any obstetric cause. Frequency of pneumonia and the number of respiratory infections in the newborns have been comparable in both groups. CONCLUSIONS: Prenatal invasive diagnosis has no influence on frequency of complications during pregnancy and delivery in the group of women less than 35 years old and more than 35 years old.     

Value of the intraoperative assessment of the depth of myometrial invasion in endometrial carcinoma

OBJECTIVES: The aim of the study was to evaluate the value of intraoperative assessment of depth of myometrial invasion in patients with FIGO stage I of the endometrial carcinoma. MATERIAL AND METHODS: A total number of 112 patients with FIGO stage I of the endometrial carcinoma undergoing surgery were enrolled in the study. All patients had undergone intraoperative assessment of the depth of myometrial invasion performed by a surgeon. The depth was determined as more or less than 50% of myometrial thickness according to FIGO classification. Gross visual estimation of the depth of myometrial invasion at the time of the operation was compared with the final histopathological report. Sensitivity, specificity and positive and negative predictive values of the method were determined by means of statistical analyses. RESULTS: The depth of the myometrial invasion was accurately determined by the surgeon in 82.1% of cases. Sensitivity and specificity were 68% and 82.1%, respectively. The accurate prediction rate of the myometrial invasion in the group of patients with well differentiated (G1) endometrial carcinoma was higher (88.4%) than in group with moderately and low differentiated tumour (78.3%). CONCLUSIONS: The accuracy of macroscopic evaluation of myometrial invasion is high and reaches up to 82.1%. The accurate determination rate increases if the differentiation of tumour is higher.     

Pelvic osteoid osteoma in a skeletally mature female

Osteoid osteoma is the most common bone-producing tumor that typically presents with "throbbing night pain" and that improves dramatically with use of low-dose salicylates. Few cases of pelvic osteoid osteoma have been reported, and most have involved patients younger than age 30. Surgical excision classically has been the treatment of choice, but, recently, less invasive modalities, including radiofrequency ablation, have begun to supplant surgical management of osteoid osteoma, resulting in a decrease in the need for definitive surgical diagnosis and treatment. We present a rare case of osteoid osteoma in the pelvis of a woman older than age 30.     

Ex vivo Search for Sentinel Node in Postmastectomy Specimens: Should We Use a Transverse Incision for Mastectomy?

Background According to the concept of sentinel node (SN), the lymphatic pathway leading to SN should be regarded as the main and the most important lymphatic route from primary tumor to regional lymph nodes. We performed ex vivo blue-dye SN mapping in postmastectomy specimens to assess whether the main lymphatic tract leading to SN is completely removed during mastectomy. We assumed that ex vivo identification of SN may be possible only if the entire lymphatic tract leading to sentinel node is removed from within the postmastectomy specimen. Methods Blue dye (1 mL) was injected intracutaenously, periareolary into each of 28 postmastectomy specimens. In 13 cases mastectomy was performed with the use of transverse skin incision; in 15 cases oblique incision was used. Results The use of transverse skin incision during modified radical mastectomy allowed identification of the sentinel node and removal of the entire lymphatic pathway leading to sentinel node only in 4 of 15 cases (31%). Conversely, the use of oblique skin incision during modified radical mastectomy allowed identification of the sentinel node and removal of the entire lymphatic pathway leading to sentinel node in 12 of 15 cases (80%). Conclusions Our experiment revealed that the use of transverse skin incision during modified radical mastectomy may not be the best choice for breast cancer patients. In our opinion, this observation may be especially important for patients not irradiated postoperatively.