New powder reuse schema in laser-based powder bed fusion of polymers.

The laser-based powder bed fusion of polymers (PBF-LB/P) process often utilizes a blend of powders with varying degrees of degradation. Specifically, for polyamide 12, the traditional reuse schema involves mixing post-processed powder with virgin powder at a predetermined ratio before reintroducing it to the process. Given that only about 15% of the powder is utilized in part production, and powders are refreshed in equal proportions, there arises a challenge with the incremental accumulation of material across build cycles. To mitigate the consumption of fresh powder relative to the actual material usage, this study introduces the incorporation of recycled material into the PBF-LB/P process. This new powder reuse schema is presented for the first time, focusing on the laser sintering process. The characteristics of the recycled powder were evaluated through scanning electron microscopy, differential scanning calorimetry, X-ray diffraction, particle size distribution, and dynamic powder flowability assessments. The findings reveal that waste powders can be effectively reused in PBF-LB/P to produce components with satisfactory mechanical properties, porosity levels, dimensional accuracy, and surface quality.

Magnetoelectric Properties of Multiferroic Composites Based on BaTiO3 and Nickel-Zinc Ferrite Material.

The purpose of the present study was to learn the morphological, structural, ferroelectric, dielectric, electromechanical, magnetoelectric, and magnetic properties, and DC conductivity of BaTiO3-Ni0.64Zn0.36Fe2O4 (BT-F) multiferroic composites compacted via the free sintering method. The influence of the ferrite content in ceramic composite materials on the functional properties is investigated and discussed. X-ray diffraction studies confirmed the presence of two main phases of the composite, with strong reflections originating from BaTiO3 and weak peaks originating from nickel-zinc ferrite. BT-F ceramic composites have been shown to exhibit multiferroism at room temperature. All studied compositions have high permittivity values and low dielectric loss, while the ferroelectric properties of the BT component are maintained at a high level. On the other hand, magnetic properties depend on the amount of the ferrite phase and are the strongest for the composition with 15 wt.% of F (magnetization at RT is 4.12 emu/g). The magnetoelectric coupling between BT and F phases confirmed by the lock-in technique is the largest for 15 wt.% ferrite. In the present work, the process conditions of the free sintering method for obtaining BT-F multiferroic composite with good electrical and magnetic properties (in one material) were optimized. An improved set of multifunctional properties allows the expansion of the possibilities of using multiferroic composites in microelectronics.

Extreme Case of Surgical Port Metastasis in Ovarian Cancer.

Ovarian cancer accounts for more deaths than any other malignancy of the female reproductive system. Early diagnosis of this disease is difficult because there are no systematic opportunistic screening methods. At advanced stages, diagnostic laparoscopy is the first step in confirming disease advancement and obtaining samples for genetic and pathologic examination needed to start chemotherapy. Swiftly starting oncological treatment is crucial for increasing the survival rate in these patients. We present the case of a 51-year-old woman with metastatic International Federation of Gynecology and Obstetrics (FIGO) stage IIIC ovarian cancer who had delayed her therapy after initial laparoscopy due to COVID-19 infection and presented with an extreme case of surgical port metastasis.

Electric and Magnetic Properties of the Multiferroic Composites Made Based on Pb(Fe1/2Nb1/2)1-xMnxO3 and the Nickel-Zinc Ferrite.

This work presents the electrophysical properties of the multiferroic ceramic composites obtained as a result of combining both magnetic and ferroelectric material. The ferroelectric components of the composite are materials with the following chemical formulas: PbFe0.5Nb0.5O3 (PFN), Pb(Fe0.495Nb0.495Mn0.01)O3 (PFNM1), and Pb(Fe0.49Nb0.49Mn0.02)O3 (PFNM2), while the magnetic component of the composite is the nickel-zinc ferrite (Ni0.64Zn0.36Fe2O4 marked as F). The crystal structure, microstructure, DC electric conductivity, and ferroelectric, dielectric, magnetic, and piezoelectric properties of the multiferroic composites are performed. The conducted tests confirm that the composite samples have good dielectric and magnetic properties at room temperature. Multiferroic ceramic composites have a two-phase crystal structure (ferroelectric from a tetragonal system and magnetic from a spinel structure) without a foreign phase. Composites with an admixture of manganese have a better set of functional parameters. The manganese admixture increases the microstructure's homogeneity, improves the magnetic properties, and reduces the electrical conductivity of composite samples. On the other hand, in the case of electric permittivity, a decrease in the maximum values of εm is observed with an increase in the amount of manganese in the ferroelectric component of composite compositions. However, the dielectric dispersion at high temperatures (associated with high conductivity) disappears.

Colonization and Healthcare-Associated Infection of Carbapenem-Resistant Enterobacteriaceae, Data from Polish Hospital with High Incidence of Carbapenem-Resistant Enterobacteriaceae, Does Active Target Screening Matter?

The objective of the study was to analyse the incidence of carbapenem-resistant Enterobacteriaceae (CRE) at a provincial hospital from 2019-2021. Multiplex PCR was used to detect the presence of carbapenemase genes. There were 399 cases of CRE detected in total in the analysed period, including 104 healthcare-associated infections. Out of the isolated CRE, 97.7% were Klebsiella pneumoniae with OXA-48 or KPC genes. Overall, among the identified CRE genes, the most frequently present genes were the ones mediating oxacillinase OXA-48 (71%) and KPC (26%), and significantly less often New Delhi NDM metallo-ß-lactamase (2.5%). Moreover, two isolates produced two carbapenemases, i.e., OXA-48 and KPC. The conducted research demonstrates that there is a constant need for continuous monitoring of the occurrence of CRE strains and the hospital antibiotic policy, as well as the implementation of procedures to prevent CRE transmission by medical personnel and hospital support staff.

The Effect of Postprocessing on the Fatigue Properties of Ti-5Al-5Mo-5V-1Cr-1Fe Produced Using Electron Beam Melting.

Despite the significant potential advantages of processing Ti-5Al-5Mo-5V-1Cr-1Fe alloy (Ti-55511) using Electron Beam Melting (PBF-EB/M), when compared to conventional manufacturing technologies, the resulting internal defects are an important characteristic of such additive technologies and can highly decrease mechanical properties. One of the most dangerous defects formed during metal additive manufacturing processes are material discontinuities such as a lack of fusion. Defects of this type, due to their "flat" nature, are difficult to characterize. For cycle-loaded specimens, where the loading force acts perpendicular to the lack-of-fusion plane, defects of this type can significantly reduce fatigue properties. This paper presents the results of research aimed at improving the fatigue properties of Ti55511 alloy by reducing the influence of the lack-of-fusion defect on fatigue damage. The static and fatigue properties of specimens in the as-built state, as well as after hot isostatic pressing (HIP) treatment, were analyzed. The effect of HIP on both the reduction of pores and the degree of sphericity when using the X-ray computed tomography (XCT) system was presented. The change in the microstructure after HIP was analyzed in terms of the change in the size of individual phases, as well as the change in the phase ratio. This paper also contains a fractographic analysis of the samples after tensile and fatigue tests.

Effect of Ni Substitution on the Structural, Magnetic, and Electronic Structure Properties of Gd0.4Tb0.6(Co1-xNix)2 Compounds.

The comprehensive research of magnetic and electronic structure properties of the new class of Gd0.4Tb0.6(Co1-xNix)2 compounds, crystallizing in the cubic Laves phase (C15), is reported. The magnetic study was completed with electrical resistivity and electronic structure investigations. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that all compounds undergo a magnetic phase transition of the second type. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (µ0H), which varied from 0.1 to 7 T. For each compound, the ΔSM had a maximum around the Curie temperature. Both values of the |ΔSMmax| and relative cooling power RCP parameters increased with increasing nickel content. It is shown that structural disorder upon Co/Ni substitution influences some magnetic parameters. The magnetic moment values of Co atoms determined from different methods are quantitatively consistent. From the M(T) dependency, the exchange integrals JRR, JRT, and JTT between rare-earths (R) and transition metal (T) moments were evaluated within the mean-field theory (MFT) approach. The experimental study of the electronic structure performed with the use of the X-ray photoelectron spectroscopy (XPS) was completed by calculations using the full-potential linearized augmented plane waves (FP-LAPW) method based on the density functional theory (DFT). The calculations explained experimentally observed changes in the XPS valence band spectra upon the Ni/Co substitution.

Interatomic Potential for InP.

Classical modeling of structural phenomena occurring in InP crystal, for example plastic deformation caused by contact force, requires an interatomic interaction potential that correctly describes not only the elastic properties of indium phosphide but also the pressure-induced reversible phase transition B3↔B1. In this article, a new parametrization of the analytical bond-order potential has been developed for InP. The potential reproduces fundamental physical properties (lattice parameters, cohesive energy, stiffness coefficients) of the B3 and B1 phases in good agreement with first-principles calculations. The proposed interaction model describes the reversibility of the pressure-induced B3↔B1 phase transition as well as the formation of native point defects in the B3 phase.

Influence of the AlSi7Mg0.6 Aluminium Alloy Powder Reuse on the Quality and Mechanical Properties of LPBF Samples.

Additive manufacturing (AM) is dynamically developing and finding applications in different industries. The quality of input material is a part of the process and of the final product quality. That is why understanding the influence of powder reuse on the properties of bulk specimens is crucial for ensuring the repeatable AM process chain. The presented study investigated the possibility of continuous reuse of AlSi7Mg0.6 powder in the laser powder bed fusion process (LPBF). To date, there is no study of AlSi7Mg0.6 powder reuse in the LPBF process to be found in the literature. This study aims to respond to this gap. The five batches of AlSi7Mg0.6 powder and five bulk LPBF samples series were characterised using different techniques. The following characteristics of powders were analysed: the powder size distribution (PSD), the morphology (scanning electron microscopy-SEM), the flowability (rotating drum analysis), and laser light absorption (spectrophotometry). Bulk samples were characterised for microstructure (SEM), chemical composition (X-ray fluorescence spectrometry-XRF), porosity (computed tomography-CT) and mechanical properties (tensile, hardness). The powder was reused in subsequent processes without adding (recycling/rejuvenation) virgin powder (collective ageing powder reuse strategy). All tested powders (powders P0-P4) and bulk samples (series S0-S3) show repeatable properties, with changes observed within error limits. Samples manufactured within the fifth reuse cycle (series S4) showed some mean value changes of measured characteristics indicating initial degradation. However, these changes also mostly fit within error limits. Therefore, the collective ageing powder reuse strategy is considered to give repeatable LPBF process results and is recommended for the AlSi7Mg0.6 alloy within at least five consecutive LPBF processes.

Effect of the Indentation Load on the Raman Spectra of the InP Crystal.

Nanoindentations and the Raman spectroscopy measurements were carried out on the (001) surface of undoped and S-doped InP crystal. The samples were indented with the maximum load ranging from 15 mN to 100 mN. The phase transition B3→B1 was not confirmed by spectroscopic experiments, indicating a plastic deformation mechanism governed by dislocations activity. Increasing the maximum indentation load shifts and the longitudinal and transverse optical Raman bands to lower frequencies reveals a reduction in the elastic energy stored in the plastic zone right below the indentation imprint. Mechanical experiments have shown that a shift in Raman bands occurs alongside the indentation size effect. Indeed, the hardness of undoped and S-doped InP crystal decreases as a function of the maximum indentation load.

Binder jetting 3D printing of challenging medicines: From low dose tablets to hydrophobic molecules.

Increasing access to additive manufacturing technologies utilising easily available desktop devices opened novel ways for formulation of personalized medicines. It is, however, challenging to propose a flexible and robust formulation platform which can be used for fabrication of tailored solid dosage forms composed of APIs with different properties (e.g., hydrophobicity) without extensive optimization. This manuscript presents a strategy for formulation of fast dissolving tablets using binder jetting (BJ) technology. The approach is demonstrated using two model APIs: hydrophilic quinapril hydrochloride (QHCl, logP = 1.4) and hydrophobic clotrimazole (CLO, logP = 5.4). The proposed printing method uses inexpensive, well known, and easily available FDA approved pharmaceutical excipients. The obtained model tablets had uniform content of the drug, excellent mechanical properties, and highly porous structure resulting in short disintegration time and fast dissolution rate. The tablets could be scaled and obtained in predesigned shapes and sizes. The proposed method may find its application in the early stages of drug development where high flexibility of the formulation is required and the amount of available API is limited.

Flexural Pseudo-Ductility Effect in Hybrid GFRP/CFRP Bars under Static Loading Conditions.

The problem with composite rebars in the civil engineering industry is often described as the material's brittleness while overloaded. To overcome this drawback, researchers pay attention to the pseudo-ductility effect. The paper presents four-point bending tests of pure unidirectional (UD) rods with additional composite layers obtained by filament winding and hand braiding techniques. Two types of core materials, glass FRP (fibre reinforced polymer) and carbon FRP, were used. Regarding the overwrapping material, the filament winding technique utilized carbon and glass roving reinforcement in the epoxy matrix, while in the case of hand braiding, the carbon fibre sleeve was applied with the epoxy matrix. Microstructural analysis using scanning electron microscopy (SEM) and computed tomography (CT) was performed to reveal the structural differences between the two proposed methods. Mechanical test results showed good material behaviour exhibiting the pseudo-ductility effect after the point of maximum force. The two applied overwrapping techniques had different influences on the pseudo-ductility effect. Microstructural investigation revealed differences between the groups of specimens that partially explain their different characters during mechanical testing.

On Incipient Plasticity of InP Crystal: A Molecular Dynamics Study.

With classical molecular dynamics simulations, we demonstrated that doping of the InP crystal with Zn and S atoms reduces the pressure of the B3→B1 phase transformation as well as inhibits the development of a dislocation structure. On this basis, we propose a method for determining the phenomenon that initiates nanoscale plasticity in semiconductors. When applied to the outcomes of nanoindentation experiments, it predicts the dislocation origin of the elastic-plastic transition in InP crystal and the phase transformation origin of GaAs incipient plasticity.

Influence of Dissolving Fe-Nb-B-Dy Alloys in Zirconium on Phase Structure, Microstructure and Magnetic Properties.

This paper refers to the structural and magnetic properties of [(Fe80Nb6B14)0.88Dy0.12]1-xZrx (x = 0; 0.01; 0.02; 0.05; 0.1; 0.2; 0.3; 0.5) alloys obtained by the vacuum mold suction casting method. The analysis of the phase contribution indicated a change in the compositions of the alloys. For x < 0.05, occurrence of the dominant Dy2Fe14B phase was observed, while a further increase in the Zr content led to the increasing contribution of the Fe-Zr compounds and, simultaneously, separation of crystalline Dy. The dilution of (Fe80Nb6B14)0.88Dy0.12 in Zr strongly influenced the magnetization processes of the examined alloys. Generally, with the increasing x parameter, we observed a decrease in coercivity; however, the unexpected increase in magnetic saturation and remanence for x = 0.2 and x = 0.3 was shown and discussed.

Enhancement of Hard Magnetic Properties in Fraktal-Like Nano and Mesoscopic Grains.

The paper refers to Monte Carlo magnetic simulations for fractal-like nano and mesoscopic grains. The analyzed objects differed in the size, surface development, magnetic anisotropy and the spin values attributed to the system nodes inside the fractal. Such an approach allowed us to determine their magnetization processes as well as optimization characteristics in the direction to enhancement of hard magnetic properties. As it was shown, the size effects depend on the chosen value of magnetic anisotropy. In the case of fractals with ultra-high coercivity, the decreasing of their size leads to deterioration of coercivity, especially for the high surface to volume ratio. Opposite effects were observed for soft magnetic fractals when the nanostructure caused an appearance of the coercive field, and the maximum of energy product was predictably significantly higher than for conventional rare earths' free permanent magnets.

The Effect of Pore Size Distribution and l-Lysine Modified Apatite Whiskers (HAP) on Osteoblasts Response in PLLA/HAP Foam Scaffolds Obtained in the Thermally Induced Phase Separation Process.

In this research, we prepared foam scaffolds based on poly(l-lactide) (PLLA) and apatite whiskers (HAP) using thermally induced phase separation technique supported by the salt leaching process (TIPS-SL). Using sodium chloride having a size of (a) 150-315 µm, (b) 315-400 µm, and (c) 500-600 µm, three types of foams with different pore sizes have been obtained. Internal structure of the obtained materials has been investigated using SEM as well as µCT. The materials have been studied by means of porosity, density, and compression tests. As the most promising, the composite prepared with salt size of 500-600 µm was prepared also with the l-lysine modified apatite. The osteoblast hFOB 1.19 cell response for the scaffolds was also investigated by means of cell viability, proliferation, adhesion/penetration, and biomineralization. Direct contact cytotoxicity assay showed the cytocompatibility of the scaffolds. All types of foam scaffolds containing HAP whiskers, regardless the pore size or l-lysine modification induced significant stimulatory effect on the cal-cium deposits formation in osteoblasts. The PLLA/HAP scaffolds modified with l-lysine stimulated hFOB 1.19 osteoblasts proliferation. Compared to the scaffolds with smaller pores (150-315 µm and 315-400 µm), the PLLA/HAP foams with large pores (500-600 µm) promoted more effective ad-hesion of osteoblasts to the surface of the biomaterial.

X-ray Computed Tomography for the Development of Ballistic Composite.

This paper presents the results of research on ballistic panels made of polymer-matrix composites (PMCs). The analysis covers two types of composites produced by the authors based on high-density polyethylene (PEHD) and polypropylene (PP) reinforced with aramid fabric. Ballistic tests were carried out with the use of two types of projectile: 0.38 Special, and 9 × 19 Parabellum, which are characterized by different velocity and projectile energy. The study presents the X-ray computed tomography (XCT) analysis for structure assessment of ballistic panels and its impact behavior, further compared to the results of computer simulations conducted using the numerical analysis. The quality of the manufactured panels and their damage caused by a ballistic impact was assessed using a multi-scale geometry reconstruction. The mesoscale XCT allowed the internal composite geometry to be analyzed, as well as a unit cell of the representative volume element (RVE) model to be built. The RVE model was applied for homogenization and finite element (FEA) simulation of projectile penetration through the ballistic panel. The macroscale XCT investigation allowed for the quantitative description of the projectile's impact on the degree of delamination and deformation of the panels' geometry.

Multidrug-Resistant Micro-Organisms Associated with Urinary Tract Infections in Orthopedic Patients: A Retrospective Laboratory-Based Study.

BACKGROUND: The risk of healthcare-associated infections (HAIs) in surgical wards remains closely related to the type of surgery and procedures performed on patients. Those factors also condition the risk of various forms of clinical infections, especially urinary tract infections (UTIs). UTIs are most frequently (70-80% of cases) caused by the use of bladder catheter in the perioperative period. The aim of this study was to perform an epidemiological and microbiological analysis of UTIs in orthopedic patients, with an emphasis on multidrug-resistant (MDR) micro-organisms. Methods: The study was conducted in a 38-bed Department of Orthopedic-Traumatic Surgery in Sosnowiec, Poland. 5239 patients, operated on in 2013-2015, were included in the study. The urinary catheter use rate was 30.7%. Laboratory-based study used the UTI definition of the HAI-Net program. A micro-organism was declared MDR if it was resistant to at least one antibiotic from three or more groups of antibacterial drugs, and extensively drug-resistant (XDR) if it was sensitive to antibiotics from no more than two groups of drugs. Results: The UTI incidence was 3.2% (168 cases), the CA-UTI incidence density was 9.6/1000 catheter days. The highest risk of UTI was found in patients aged 75 or older. Monomicrobial cultures were detected in 163 specimens (78% of all microbiologically confirmed UTIs). Gram-negative flora prevailed among the micro-organisms, the predominantly isolated Enterobacteriaceae being Escherichia coli and Klebsiella pneumoniae. In 16 patients (7.7% of microbiologically confirmed UTIs), yeast infection was confirmed. Isolated micro-organisms were fully sensitive to carbapenems. Gram-negative bacilli showed the lowest sensitivity to extended substrate spectrum penicillins and fluoroquinolones (37-64%), as well as to trimethoprim-sulfamethoxazole (50%). The MDR prevalence was 24.4%. Conclusions The presented data indicates that UTIs are a significant problem in the studied population, so is antimicrobial resistance, especially to quinolones, and extended-spectrum cephalosporins, which are often used as first-line therapy. To tackle the problem of high UTI incidence and MDR prevalence, reducing the UTI risk factors should be prioritized.

Magnetic Properties and the Electronic Structure of the Gd0.4Tb0.6Co2 Compound.

We report on the comprehensive experimental and theoretical studies of magnetic and electronic structural properties of the Gd0.4Tb0.6Co2 compound crystallization in the cubic Laves phase (C15). We present new results and compare them to those reported earlier. The magnetic study was completed with electronic structure investigations. Based on magnetic isotherms, magnetic entropy change (ΔSM) was determined for many values of the magnetic field change (Δµ0H), which varied from 0.1 to 7 T. In each case, the ΔSM had a maximum around room temperature. The analysis of Arrott plots supplemented by a study of temperature dependency of Landau coefficients revealed that the compound undergoes a magnetic phase transition of the second type. From the M(T) dependency, the exchange integrals between rare-earth R-R (JRR), R-Co (JRCo), and Co-Co (JCoCo) atoms were evaluated within the mean-field theory approach. The electronic structure was determined using the X-ray photoelectron spectroscopy (XPS) method as well as by calculations using the density functional theory (DFT) based Full Potential Linearized Augmented Plane Waves (FP-LAPW) method. The comparison of results of ab initio calculations with the experimental data indicates that near TC the XPS spectrum collects excitations of electrons from Co3d states with different values of exchange splitting. The values of the magnetic moment on Co atoms determined from magnetic measurements, estimated from the XPS spectra, and results from ab initio calculations are quantitatively consistent.

From Atomic Level to Large-Scale Monte Carlo Magnetic Simulations.

This paper refers to Monte Carlo magnetic simulations for large-scale systems. We propose scaling rules to facilitate analysis of mesoscopic objects using a relatively small amount of system nodes. In our model, each node represents a volume defined by an enlargement factor. As a consequence of this approach, the parameters describing magnetic interactions on the atomic level should also be re-scaled, taking into account the detailed thermodynamic balance as well as energetic equivalence between the real and re-scaled systems. Accuracy and efficiency of the model have been depicted through analysis of the size effects of magnetic moment configuration for various characteristic objects. As shown, the proposed scaling rules, applied to the disorder-based cluster Monte Carlo algorithm, can be considered suitable tools for designing new magnetic materials and a way to include low-level or first principle calculations in finite element Monte Carlo magnetic simulations.