3D printed UV-sensing optical fiber probes: manufacturing, properties, and performance.

UV sensing 3D printed optical fiber hydrogels provide a flexible and precise method of remotely of detecting exposure to UV radiations. The optical fibers were created using digital light processing 3D printing technique with hydrogel composites, including micro-sized photochromic dyes (pink, blue and their combination). When exposed to ultraviolet (UV) radiation, these dyes exhibited specific absorption characteristics, resulting in significant decreases in both reflection and transmittance mode spectra at 560 nm, 620 nm, and 590 nm. Optical fibers of lengths 1, 2, and 3 cm were manufactured in two orientations: vertical and horizontal. Scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction were utilized to characterize the printed fiber probes. The optical performance of the fibers was tested using customized measurement setups. The reflection and transmission of the printed fibers reduced as the length increased due to optical losses. Reflection and transmisson loss of 20-40% can be observed when the length is increased from 1 to 3 cm. The maximum loss in reflection is observed for pink fiber in the presence of UV irradiation. Also, the type of powder used impacted the response and retraction time, whereas the mixed fiber showed the highest response time of 12-20 s under various conditions. The pink dye added fiber probes shows quick response to UV radiation. An increase in the response time is observed with increasing fiber length. The impact of printing orientation on the transmission and reflectance mode operations of optical fibers was assessed. In addition, the stability of the fiber probes are assesed using a green laser having wavelength 532 nm. This work comprehensively examines the optical properties, manufacturing procedures, and sensing capacities of UV-sensitive photochromic optical fiber sensors.

Preliminary investigations into the use of the ancient pigments Han blue and Han purple as luminescent dusting powders for the detection of latent fingermarks.

Here we present our preliminary studies into the inorganic pigments Han blue (BaCuSi4O10) and Han purple (BaCuSi2O6) as near-infrared luminescent fingerprint dusting powders. These pigments were developed in ancient China around 800 BCE and both show luminescence in the NIR region. There remains, however, ambiguity in the literature concerning their photophysical properties. Samples of Han blue and Han purple artist's pigments were characterized by optical microscopy, infrared, ultraviolet-visible absorbance and luminescence spectroscopy. Their performance as fingerprint dusting powders, without any further treatment, on non-porous surfaces were compared to exfoliated lipophilic coated Egyptian blue and commercial fluorescent powders in a pilot study. These results demonstrate for the first time that both ancient pigments show promise as alternative dusting powders for latent fingermarks.

Synthesis and Characterisation of Nanocrystalline CoxFe1-xGDC Powders as a Functional Anode Material for the Solid Oxide Fuel Cell.

The necessity for high operational temperatures presents a considerable obstacle to the commercial viability of solid oxide fuel cells (SOFCs). The introduction of active co-dopant ions to polycrystalline solid structures can directly impact the physiochemical and electrical properties of the resulting composites including crystallite size, lattice parameters, ionic and electronic conductivity, sinterability, and mechanical strength. This study proposes cobalt-iron-substituted gadolinium-doped ceria (CoxFe1-xGDC) as an innovative, nickel-free anode composite for developing ceramic fuel cells. A new co-precipitation technique using ammonium tartrate as the precipitant in a multi-cationic solution with Co2+, Gd3+, Fe3+, and Ce3+ ions was utilized. The physicochemical and morphological characteristics of the synthesized samples were systematically analysed using a comprehensive set of techniques, including DSC/TGA for a thermal analysis, XRD for a crystallographic analysis, SEM/EDX for a morphological and elemental analysis, FT-IR for a chemical bonding analysis, and Raman spectroscopy for a vibrational analysis. The morphological analysis, SEM, showed the formation of nanoparticles (≤15 nm), which corresponded well with the crystal size determined by the XRD analysis, which was within the range of ≤10 nm. The fabrication of single SOFC bilayers occurred within an electrolyte-supported structure, with the use of the GDC as the electrolyte layer and the CoO-Fe2O3/GDC composite as the anode. SEM imaging and the EIS analysis were utilized to examine the fabricated symmetrical cells.

Inhaled Nanoparticulate Systems: Composition, Manufacture and Aerosol Delivery.

An increasing growth in nanotechnology is evident from the growing number of products approved in the past decade. Nanotechnology can be used in the effective treatment of several pulmonary diseases by developing therapies that are delivered in a targeted manner to select lung regions based on the disease state. Acute or chronic pulmonary disorders can benefit from this type of therapy, including respiratory distress syndrome (RDS), chronic obstructive pulmonary disease (COPD), asthma, pulmonary infections (e.g. tuberculosis, Yersinia pestis infection, fungal infections, bacterial infections, and viral infections), lung cancer, cystic fibrosis (CF), pulmonary fibrosis, and pulmonary arterial hypertension. Modification of size and surface property renders nanoparticles to be targeted to specific sites, which can serve a vital role in innovative pulmonary drug delivery. The nanocarrier type chosen depends on the intended purpose of the formulation and intended physiological target. Liquid nanocarriers and solid-state nanocarriers can carry hydrophilic and hydrophobic drugs (e.g. small molecular weight drug molecules, large molecular weight drugs, peptide drugs, and macromolecular biological drugs), while surface modification with polymer can provide cellular targeting, controlled drug release, and/or evasion of phagocytosis by immune cells, depending on the polymer type. Polymeric nanocarriers have versatile architectures, such as linear, branched, and dendritic forms. In addition to the colloidal dispersion liquid state, the various types of nanoparticles can be formulated into the solid state, offering important unique advantages in formulation versatility and enhanced stability of the final product. This chapter describes the different types of nanocarriers, types of inhalation aerosol device platforms, liquid aerosols, respirable powders, and particle engineering design technologies for inhalation aerosols.

Different Carriers for Use in Dry Powder Inhalers: Characteristics of Their Particles.

In contemporary times, there has been a rise in the utilization of dry powder inhalers (DPIs) in the management of pulmonary and systemic diseases. These devices underwent a swift advancement in terms of both the equipment utilized and the formulation process. In this review, the carrier physicochemical characteristics that influence DPI performance are discussed, focusing its shape, morphology, size distribution, texture, aerodynamic diameter, density, moisture, adhesive and detachment forces between particles, fine carrier particles, and dry powder aerosolization. To promote the deposition of the active principal ingredient deep within the pulmonary system, advancements have been made in enhancing these factors and surface properties through the application of novel technologies that encompass particle engineering. So far, the most used carrier is lactose showing some advantages and disadvantages, but other substances and systems are being studied with the intention of replacing it. The final objective of this review is to analyze the physicochemical and mechanical characteristics of the different carriers or new delivery systems used in DPI formulations, whether already on the market or still under investigation. [Figure: see text].

Development of a proliposomal pretomanid dry powder inhaler as a novel alternative approach for combating pulmonary tuberculosis.

Multidrug-resistant tuberculosis (MDR-TB) and extensively drug-resistant tuberculosis (XDR-TB) continue as public health concerns. Inhaled drug therapy for TB has substantial benefits in combating the causal agent of TB (Mycobacterium tuberculosis). Pretomanid is a promising candidate in an optional combined regimen for XDR-TB. Pretomanid has demonstrated high potency against M. tuberculosis in both the active and latent phases. Conventional spray drying was used to formulate pretomanid as dry powder inhalers (DPIs) for deep lung delivery using a proliposomal system with a trehalose coarse excipient to enhance the drug solubility. Co-spray drying with L-leucine protected hygroscopic trehalose in formulations and improved powder aerosolization. Higher amounts of L-leucine (40-50 % w/w) resulted in the formation of mesoporous particles with high percentages of drug content and entrapment efficiency. The aerosolized powders demonstrated both geometric and median aerodynamic diameters < 5 µm with > 90 % emitted dose and > 50 % fine particle fraction. Upon reconstitution in simulated physiological fluid, the proliposomes completely converted to liposomes, exhibiting suitable particle sizes (130-300 nm) with stable colloids and improving drug solubility, leading to higher drug dissolution compared to the drug alone. Inhalable pretomanid showed higher antimycobacterial activity than pretomanid alone. The formulations were safe for all broncho-epithelial cell lines and alveolar macrophages, thus indicating their potential suitability for DPIs targeting pulmonary TB.

Dry powder formulations of hyperimmune serum.

Effective strategies against the spread of respiratory viruses are needed, as tragically demonstrated during the COVID-19 pandemic. Apart from vaccines, other preventive or protective measures are necessary: one promising strategy involves the nasal delivery of preventive or protective agents, targeting the site of initial infection. Harnessing the immune system's ability to produce specific antibodies, a hyperimmune serum, collected from an individual vaccinated against SARS-CoV-2, was formulated as a dry powder for nasal administration. The selection of adequate excipients and process are key to maintaining protein stability and modulating the aerodynamic properties of the powders for reaching the desired respiratory regions. To this end, a hyperimmune serum was formulated with trehalose and mannitol as bulking agents during spray drying, then the ability of the redissolved immunoglobulins to bind Spike protein was verified by ELISA; foetal bovine serum was formulated in the same conditions as a reference. Moreover, a seroneutralization assay against SARS-CoV-2 pseudoviruses generated from different variants of concern was performed. The neutralizing ability of the serum was slightly reduced with respect to the starting serum when trehalose was used as a bulking agent. The powders were loaded in hypromellose capsules and aerosolized employing a nasal insufflator in an in vitro model of the nasal cavity connected to a Next Generation Impactor. The analysis of the powder distribution confirmed that all powders were inhalable and could target, at the same time, the upper and the lower airways. This is a preliminary proof-of-concept that this approach can constitute an effective strategy to provide broad coverage and protection against SARS-CoV-2, and in general against viruses affecting the airway. According to blood availability from donors, pools of hyperimmune sera could be rapidly formulated and administered, providing a simultaneous and timely neutralization of emerging viral variants.

A method to assess the quality of additive manufacturing metal powders using the triboelectric charging concept.

A new method to assess the quality of additive manufacturing (AM) metal powders using the triboelectric charging concept is demonstrated using CpTi, Ti6Al4V, AlSi10Mg, IN 738, and SS 316L powders. For each powder tested, the surface chemical composition was first analyzed using X-ray photoelectron spectroscopy (XPS) to determine the composition of the passivation layer. Some modifications to the current GranuCharge™ setup, developed by GranuTools™, were then performed by incorporating a flow rate measuring tool to assess how tribocharging is affected as a function of flow rate. Variations in the tribocharging response have been found with the flow rate of CpTi, AlSi10Mg and SS 316L powders. Moreover, results suggest that the tribocharging behavior might not be the same even with powders fabricated with the same passivation process. Finally, the compressed exponential model of Trachenko and Zaccone was used to reproduce the tribocharging behavior of the powders. The models were found to work best when the stretch constant ß = 1.5, which is identical to the value found in other systems such as structural glasses, colloidal gels, entangled polymers, and supercooled liquids, which experience jamming when motion of individual particles become restricted, causing their motion to slow down.

Titanium dioxide in face powders and eyeshadows: Developing an analytical methodology for accessing customer safety.

BACKGROUND: Titanium dioxide (TiO2), a white powder, represents the opacifier used in many products, including drugs, foods, cosmetics, paints, and dyes. METHOD: The Uv-Vis spectrophotometry was a particularly suitable technique to quantify TiO2 in the solutions obtained from cosmetics. In this work, we determined the TiO2 content in a total of 88 samples of eye shadows and face powders of different brands and costs. Before to analyse the samples, we developed the mineralization and analysis method, in fact, fusion with potassium bisulphate would be very laborious because it must be carried out on one sample at a time and requires very long times, instead, the mineralization with the acid mixture and the aid of microwaves allowed us to solubilize six samples at the same time within 45 min. RESULTS: From the results obtained, we can state that the highest concentrations of TiO2 are found in the eyeshadows with a maximum value of 36% in a blue eyeshadow.

Combined application of artificial bone powders and concentrated growth factor membranes on the autotransplantation of mature third molars: A 5-year retrospective case series.

AIM: This study aimed to observe the efficacy and outcomes of the combined application of artificial bone powder and concentrated growth factor (CGF) membranes for tooth transplantation in cases with wide recipient sockets and small donor teeth. MATERIAL AND METHODS: A total of 36 teeth from 36 patients with wide recipient sockets and small donor teeth were enrolled. Autogenous tooth transplantation was performed using bone powders and CGF membranes. After transplantation, the visual analog scale (VAS) score, Landry Wound Healing Index, probing depth (PD), mobility, and gray value of the alveolar bone around the transplanted teeth were measured, and a patient satisfaction questionnaire was administered. All patients underwent clinical and radiographic examinations during follow-up. RESULTS: The VAS score of 16 (44.4%) cases after 1 week was 0, and 26 (72.2%) patients showed excellent gingival healing after 2-4 weeks. The PD of a few cases was deeper than 3 mm during the first month; however, returned to normal after 3 months. Although the majority of the transplanted teeth possessed mobility greater than grade I during the first month, the mobility gradually improved within 3 months. The gray value of the alveolar bone around the transplanted teeth, 1 year postoperatively showed no difference with pre-operation (p > .05). During the mean follow-up period of 42.7 months (range 20-72 months), 33 of the 36 transplanted teeth remained in situ without clinical or radiographic complications, with an overall success rate of 91.7%. CONCLUSIONS: Although the PD and mobility of the transplanted teeth were not ideal during the early stages of healing, most of the transplanted teeth had good clinical outcomes. In cases with large recipient sites accompanied by small donor teeth, autotransplantation of teeth using artificial bone powder combined with CGF membranes is a viable option and can lead to optimistic results with favorable success rates.

Three-Dimensional-Printed Composite Structures: The Effect of LSCF Slurry Solid Loading, Binder, and Direct-Write Process Parameters.

In this research, a direct-write 3D-printing method was utilized for the fabrication of inter-digitized solid oxide fuel cells (SOFCs) using ceramic materials. The cathode electrode was fabricated using the LSCF (La0.6Sr0.2Fe0.8Co0.2O3-δ) slurry loading and the Polyvinyl butyral (PVB) binder. The rheological parameters of slurries with varying LSCF slurry loading and PVB binder concentration were evaluated to determine their effect on the cathode trace performance in terms of microstructure, size, and resistance. Additionally, the dimensional shrinkage of LSCF lines after sintering was investigated to realize their influence on cathode line width and height. Moreover, the effect of the direct-write process parameters such as pressure, distance between the nozzle and substrate, and speed on the cathode line dimensions and resistance was evaluated. LSCF slurry with 50% solid loading, 12% binder, and 0.2% dispersant concentration was determined to be the optimal value for the fabrication of SOFCs using the direct-write method. The direct-write process parameters, in addition to the binder and LSCF slurry concentration ratios, had a considerable impact on the microstructure of cathode lines. Based on ANOVA findings, pressure and distance had significant effects on the cathode electrode resistance. An increase in the distance between the nozzle and substrate, speed, or extrusion pressure of the direct writing process increased the resistance of the cathode lines. These findings add to the ongoing effort to refine SOFC fabrication techniques, opening the avenues for advanced performance and efficiency of SOFCs in energy applications.

The Influence of the Grinding Media Diameter on Grinding Efficiency in a Vibratory Ball Mill.

The grinding process plays a crucial role in industry, allowing for the reduction of particle sizes of raw materials and substances to the required fineness-either as a finished product or for further technological processes. The high demand for micro- and nanopowders or suspensions is associated with the high energy consumption of the milling process. Therefore, optimizing the milling process, including correctly selecting grinding media, is essential to reduce energy consumption. This article presents experimental studies of the grinding process of a model material (quartz sand) in a laboratory vibratory mill. Five sets of grinding media with different diameters were used in the research, and grinding was conducted for various durations. The studies showed that the vibratory grinding process is efficient for each set of grinding media and grinding durations. The research has shown that conducting studies on the proper selection of mills is beneficial, especially regarding very fine grinding of various materials. The study confirmed that properly selecting grinding media sets can significantly accelerate the grinding process. For the selected technological variant, it was demonstrated that using 15 mm grinding media, compared to 12 mm, resulted in a 22.5% reduction in grinding time to achieve a specified particle size class of 0-10 µm.

Effects of Misalignment of c-axis on the Properties of Hydrogenation-Disproportionation-Desorption-Recombination Particles.

Hydrogenation-Disproportionation-Desorption-Recombination (HDDR) Nd2Fe14B particles have excellent magnetic properties, but the magnetic properties of powder are not uniform across different particle sizes. The remanence and maximum magnetic energy products of samples with a particle size of 120 µm are 14.0 kGs and 41.35 MGOe, while the products of samples with a particle size of 60 µm are only 13.3 kGs and 36.31 MGOe. The macroscopic morphology of HDDR Nd2Fe14B particles and the gradient distribution of microstructures in different micro-regions were observed. By modifying the macroscopic morphology of the particles, the poorly oriented clusters on the surface of the particles were precisely eliminated, and the remanence and maximum magnetic energy products of the particles increased to 14.5 kGs and 45 MGOe, respectively. Compared with the original particles, the samples after mechanical grinding had better grain arrangement. The effects of the nanocrystalline c-axis and field misalignment angle θ on the magnetic properties of HDDR Nd2Fe14B particles were investigated through micromagnetic simulation. The targeted removal of macroscopic defects on the particle surface contributed to a 3.6% increase in remanence and an 8.8% increase in the maximum magnetic energy product, offering a promising approach to enhance the microstructure of high-performance HDDR Nd2Fe14B particles.

Facile Synthesis of Multifunctional Mesoporous Starch-Based Microparticle for Effective Hemostasis and Wound Healing.

Uncontrolled hemorrhage and infection are the principal causes of mortality associated with trauma in both military and civilian medical settings. Modified starch granules have emerged as a safe hemostatic agent for irregular and noncompressible wounds, but their performance is constrained by limited hemostasis efficiency and modest antibacterial activity. This study reported a directed self-assembly approach for a multifunctional mesoporous starch-based microparticle loaded with chitosan and calcium ions (Ca@MSMP) used for rapid hemostasis and wound healing. Directed self-assembly of uniform Ca@MSMP with a hierarchical hollow structure in the presence of chitosan was confirmed by scanning electron microscopy (SEM) analysis and pore structure analysis. The resulting Ca@MSMP exhibited a well-defined spherical shape and uniform size of 1 µm and demonstrated excellent antibacterial activity (>95%) without hemolytic activity. Importantly, Ca@MSMP enhanced blood coagulation and platelet aggregation via the synergistic effect of rapid calcium release and chitosan-mediated electrostatic interactions, leading to a significant decrease in blood loss and reduction in hemostasis time in rat tail amputation and liver injury models. In comparative analyses, Ca@MSMP significantly outperformed the commercial hemostatic agent Quickclean, notably enhancing the healing of full-thickness skin wounds in vivo by effectively preventing infection. These results underscore the potential of this innovative hemostatic material in diverse clinical scenarios, offering effective solutions for the management of bleeding in wounds that are irregularly shaped and noncompressible.

Prevalence of multiple micronutrient powders consumption and its determinants among 6- to 23-month-old children in East Africa: a mixed effect analysis using the recent population based cross sectional national health survey.

BACKGROUND: To address iron deficiency anemia, Multiple Micronutrient Powders (MMNPs) can be sprinkled onto any semisolid diet and given to young children. There is currently no data on actual MMNPs uptake by children; hence, the study's goal was to investigate MMNPs and determinants among children aged 6-23 months in East Africa. METHODS: Data from the 2016-2022 East Africa demographic and health survey extracted from Kids Records (KR) files were used in this study. A total of 33,324 weighted 6- to 23-month-old child samples were included. For assessing model fitness and contrast, the intra-class correlation coefficient, median odds ratio, proportional change in variance, and deviance were used. A multilevel logistic regression model was applied to identify variables that may influence MMNPs intake. In the multivariable multilevel logistic regression analyses, variables were judged to be significantly linked with MMNPs intake if their p-values were < 0.05. RESULTS: In East Africa, the prevalence of MMNPs intake among infants aged 6-23 months was 6.45% (95% CI, 6.19%, 6.22%). Several factors were found to be significantly associated with MMNPs consumption. These factors include older maternal age (AOR = 1.23, 95% CI, 1.09, 1.39) and (AOR = 1.46, 95% CI, 1.23, 1.73), poorer (AOR = 0.73, 95% CI, 0.64, 0.84), middle (AOR = 0.75, 95% CI, 0.66, 0.86), richer (AOR = 0.61, 95% CI, 0.52, 0.71), and richest (AOR = 0.49, 95% CI, 0.41, 0.59) as compared to poorest, having employment status (AOR = 0.65, 95% CI, 0.59, 0.71), mass media exposure (AOR = 1.61, 95% CI, 1.35, 1.78), longer birth interval (AOR = 1.19, 95% CI, 1.28, 1.36), place of delivery (AOR = 1.46, 95% CI, 1.28,1.66), and mothers from rural areas (AOR = 0.71, 95% CI, 0.62,0.80). CONCLUSIONS: Overall, MMNPs intake was lower than the national and international recommendations. Only seven out of every hundred children received MMNPs. Improving maternal preventive health care and supporting marginalized women will have a positive impact.

Method for Determining the Coefficient of Friction Variation Pattern as a Function of Density at Low Temperatures Using the Example of Dry Ice-Steel Contact.

The developments in manufacturing technologies are expected to reduce energy input without compromising product quality. Regarding the material densification process, numerical simulation methods are applied to achieve this goal. In this case, relevant material models are built using functions that describe the variation in mechanical parameters of the material in question due to its deformation. The literature review conducted for this research has revealed a shortage of experimental research methods allowing a determination of the coefficient of friction at low temperatures, approximately 200 K. This article proposes a method for determining the friction coefficient of dry ice sliding against steel. The experimental results were analysed to obtain several functions describing the variation in the coefficient of friction. These functions were then compared using goodness-of-fit indexes. Finally, two functions with similar goodness-of-fit values were chosen. The findings of this research project will complement the already available information and may be used in various research and implementation projects related to the development or improvement of currently used crystallised carbon dioxide conversion processes.

Explainable AI: Machine Learning Interpretation in Blackcurrant Powders.

Recently, explainability in machine and deep learning has become an important area in the field of research as well as interest, both due to the increasing use of artificial intelligence (AI) methods and understanding of the decisions made by models. The explainability of artificial intelligence (XAI) is due to the increasing consciousness in, among other things, data mining, error elimination, and learning performance by various AI algorithms. Moreover, XAI will allow the decisions made by models in problems to be more transparent as well as effective. In this study, models from the 'glass box' group of Decision Tree, among others, and the 'black box' group of Random Forest, among others, were proposed to understand the identification of selected types of currant powders. The learning process of these models was carried out to determine accuracy indicators such as accuracy, precision, recall, and F1-score. It was visualized using Local Interpretable Model Agnostic Explanations (LIMEs) to predict the effectiveness of identifying specific types of blackcurrant powders based on texture descriptors such as entropy, contrast, correlation, dissimilarity, and homogeneity. Bagging (Bagging_100), Decision Tree (DT0), and Random Forest (RF7_gini) proved to be the most effective models in the framework of currant powder interpretability. The measures of classifier performance in terms of accuracy, precision, recall, and F1-score for Bagging_100, respectively, reached values of approximately 0.979. In comparison, DT0 reached values of 0.968, 0.972, 0.968, and 0.969, and RF7_gini reached values of 0.963, 0.964, 0.963, and 0.963. These models achieved classifier performance measures of greater than 96%. In the future, XAI using agnostic models can be an additional important tool to help analyze data, including food products, even online.

Effects of Induction Plasma Spheroidization on Properties of Yttria-Stabilized Zirconia Powders for Thermal Barrier Coating Applications.

In this study, the induction plasma spheroidization (IPS) technique was adopted to improve the microstructure and properties of the traditional agglomerated ZrO2-7wt%Y2O3 (YSZ) powders used in thermal barrier coating (TBC) applications. Compared with agglomerated YSZ powders, IPS-treated powder has a more desirable microstructure, and the overall performance of the spray powders for TBC preparation is significantly improved. Specifically, IPS-treated powder has a dense, solid, defect-free, and chemically uniform microstructure, and its apparent density, flowability, and powder strength are significantly improved, which is believed to substantially enhance the coating performance when prepared with this IPS-treated powder.

Experimental Investigation on Magnetic Abrasive Finishing for Internal Surfaces of Waveguides Produced by Selective Laser Melting.

To enhance the surface quality of metal 3D-printed components, magnetic abrasive finishing (MAF) technology was employed for post-processing polishing. Experimental investigation employing response surface methodology was conducted to explore the impact of processing gap, rotational speed of the magnetic field, auxiliary vibration, and magnetic abrasive particle (MAP) size on the quality enhancement of internal surfaces. A regression model correlating roughness with crucial process parameters was established, followed by parameter optimization. Ultimately, the internal surface finishing of waveguides with blind cavities was achieved, and the finishing quality was comprehensively evaluated. Results indicate that under optimal process conditions, the roughness of the specimens decreased from Ra 2.5 µm to Ra 0.65 µm, reflecting a reduction rate of 74%. Following sequential rough and fine processing, the roughnesses of the cavity bottom, side wall, and convex surface inside the waveguide reduced to 0.59 µm, 0.61 µm, and 1.9 µm, respectively, from the original Ra above 12 µm. The findings of this study provide valuable technical insights into the surface finishing of metal 3D-printed components.

Effect of Mineral Powders on the Properties of Foam Concrete Prepared by Cationic and Anionic Surfactants as Foaming Agents.

Foam concrete is a type of cement mortar in which air bubbles are introduced using an appropriate foaming agent. The complex conditions for the preparation of solid particle stabilized foams limit their wide application in construction. In this study, a method of adding small amounts of calcite (Cal) and muscovite (Mus) to the cement paste matrix is proposed to improve the properties of foam concrete prepared with cationic and anionic surfactants as foaming agents. The effects of mineral powders on the flowability, compressive strength, water absorption, pore characteristics, thermal conductivity and frost resistance of foam concrete were investigated and the enhancement mechanism was revealed by the results of XRD, low-field nuclear magnetic resonance (LF-NMR), Fourier transform infrared spectroscopy (FTIR) and SEM. The results showed that the mineral powders interacted with anionic and cationic surfactants through physical adsorption. Whether anionic or cationic surfactants were used as foaming agents, the addition of mineral powders promoted the formation of shell-like structures around the foam, thus enhancing the performance of foam concrete. As a result, the fluidity, compressive strength and frost resistance of the foam concrete increased, the water absorption and thermal conductivity decreased, and the average size of the pores decreased.