Raw Specimens Research Articles

Computer Vision-Assisted Robotized Sampling of Volatile Organic Compounds.

In conventional chemical analysis, samples are homogenized, extracted, purified, and injected into an analytical instrument manually or with a certain degree of automation. Such complex methods can provide superior performance in terms of sensitivity or selectivity. However, in some cases, it would be advantageous to possess a method that circumvents those preparatory steps, which require much attention. Here, we present a facile analytical approach to sampling volatile organic compounds (VOCs). Solid specimens emitting VOCs can be dropped onto the drop-off zone at a random position without any special alignment. A computer vision system recognizes specimen position, and a robotic arm places a sampling probe in the proximity of the specimen. The probe aspirates the VOCs─emitted by the specimen─with the aid of a suction force. A portion of the gaseous extract is transferred to the tritium-based ion source of a drift-tube ion mobility spectrometer. The ion mobility spectrum is immediately displayed in the customized graphical user interface (GUI). The sampling system also features a function for flushing extract ducts with hot nitrogen gas. Multiple specimens can be dropped for analysis at the same time. In one embodiment, the system can distinguish fresh meat from spoiled meat. When two meat specimens are placed on the drop-off zone, they are immediately sampled by the robotic arm, analyzed, and labeled on the digital image displayed on the GUI. Thus, the developed autosampling platform provides a hassle-free way of qualitative or semiquantitative analysis of raw specimens.

P-106 A novel sperm selection technique to select the most motile spermatozoa with superior genomic integrity for intrauterine insemination

Abstract Study question Does the utilization of a novel sperm selection method via microfluidics(MFSS) confer advantages over the conventional density gradient(DG) technique for couples undergoing intrauterine insemination(IUI)? Summary answer MFSS efficiently selected spermatozoa with increased motility and genomic integrity in an expedited manner, leading to an enhanced IUI clinical outcome. What is known already The first-line reproductive treatments for infertile couples are timed intercourse and IUI. In IUI, DG is commonly utilized to isolate motile spermatozoa. However, this method requires technical skills and processing time. Furthermore, DG exposes spermatozoa to silica gel particles and reactive oxygen species during centrifugation. MFSS represents a safer and more efficient sperm processing method to minimize human intervention. It has been reported by several investigators that MFSS selects spermatozoa with higher progressive motility and lower DNA fragmentation in ART. We have decided to investigate the efficacy of MFSS as an alternative method to select spermatozoa for IUI. Study design, size, duration Since 2017, post-processing semen parameters and Sperm Chromatin Fragmentation (SCF) was measured in the raw, DG-, and MFSS-processed specimens. Clinical outcomes were compared between IUI cycles using DG versus MFSS processing. Paired analyses were performed on patients who underwent history IUI-DG and subsequent IUI-MFSS, and cycles were split into natural (NC) or clomid or letrozole superovulation (CLO) cohorts. Participants/materials, setting, methods A total of 855 couples underwent 922 IUI-MFSS. Post-processing semen parameters and clinical outcomes were compared with those of 2325 age-matched couples who underwent 8322 IUI-DG during the same period. All male partners included in this study had normal semen parameters. DG was performed according to WHO, while MFSS as per manufacturer protocol(ZyMōt® Multi 850µL). SCF was assessed by TUNEL(normal threshold,≤15%). For all comparisons, +bHCG and clinical pregnancy(CPR,+FHB) were compared. Main results and the role of chance IUI-DG(maternal age:32.7±2;paternal age:37.9±6) resulted in a final concentration of 48.4±33x106/mL and motility of 88.1±4%. IUI-MFSS resulted in a decrease in a final concentration at 36.4±17x106/mL with a remarkable increase in motility at 98.6±1%(P<0.01). SCF was 6.0±4% in raw specimen, became 4.7±2% after DG, and 2.5±2% after MFSS(P<0.01). Overall, IUI-DG(n = 2325) resulted in a +bHCG of 12.7%(1065/8322) and a CPR(+FHB) of 11.0%(919/8322). IUI-MFSS(n = 855) resulted in a higher +bHCG of 16.1%(149/922,P<0.01) and a CPR of 12.5%(116/922). Next, we divided cycles into NC or CLO cohorts. In couples with NC, IUI-DG(n = 420) resulted in a +bHCG of 9.3%(132/1416) and a CPR of 8.8%(124/1416). IUI-MFSS(n = 107) resulted in a +bHCG of 11.4%(15/131) and a CPR of 11.4%(15/131). In CLO cycles, IUI-DG(n = 1990) resulted in a +bHCG of 13.0%(788/6048) and CPR of 10.9% (659/6048), while IUI-MFSS(n = 496) resulted in a significantly higher +bHCG at 17.4%(122/698) and CPR at 14.3%(100/698,P<0.01). In the paired sub-analysis, NC couples (n = 30) underwent IUI-DG and subsequently IUI-MFSS. IUI-DG resulted in a 9.4% +bHCG(7/74) and 8.1% CPR(6/74). IUI-MFSS yielded a 10.2% +bHCG(4/39) and 10.2% CPR(4/39). CLO couples (n = 132) underwent IUI-DG and resulted in a 13.6% +bHCG(85/623) and 11.2% CPR(70/623), followed by IUI-MFSS yielding a 15.2% +bHCG(27/178) and 12.4% CPR(22/178). Limitations, reasons for caution IUI-MFSS cycles resulted in an increased proportion of progressively motile spermatozoa, with a superior genomic integrity and higher clinical outcome. The benefit of MFSS may be somewhat limited because of the low SCF of this particular cohort and only a larger case series would be able to confirm this finding. Wider implications of the findings DG is labor intensive, technician-dependent, and unable to meaningfully ameliorate SCF. MFSS, while reducing exposure to reactive oxygen species, grants the highest sperm progressive motility with superior genomic integrity that may be responsible for an improved pregnancy outcome. Trial registration number not applicable

Amazon açaí fibre–Portland cement compatibility: a challenge to produce cement-bonded fibreboards?

The açaí waste from the Amazon contains short fibres that show potential for reinforcing cement-bonded fibreboards (CBFBs), although their compatibility with the cement matrix is still unknown. The aim of this work was to characterise raw and pretreated açaí fibres and analyse their compatibility with Portland cement by different techniques, alongside developing a CBFB. The fibres were subjected to thermal (180, 200 and 220°C), cold and hot water, alkaline (NaOH) and bleaching (NaOH–H2O2) pretreatments. The chemical and water pretreatments raised the fibre crystalline indexes (28–57%). The chemical pretreatments individualised the fibre bundles and removed hemicelluloses. Alkali-pretreated and raw fibres had the highest (96%) and lowest (65%) cement compatibility indexes. Portlandite and ettringite appeared after 24 h for most pastes, but were delayed for raw and 220°C-pretreated fibres. In contrast, only the raw fibre specimens reached the required compression strength of 34 MPa after 28 days; hence, they were chosen to produce a CBFB. The boards showed proper thickness swelling (1.4%), but low bending strength (modulus of elasticity = 647.8 MPa; modulus of rupture = 1.9 MPa). Overall, the fibre modifications improved the compatibility with cement, but not the composite's mechanical strength. Açaí-fibre CBFB is a promising building material, but future studies must overcome its poor mechanical performance.

Antibacterial potential of lactic acid bacteria isolated from raw cow milk in Sylhet district, Bangladesh: A molecular approach.

The most prevalent probiotic bacterium employed in the food industry is Lactobacillus because it can produce metabolites with antibacterial capabilities and exhibits hostility towards infections and microorganisms that cause spoilage. This study set out to identify naturally occurring Lactobacillus and plantaricin (pln EF) coding genes in raw cow milk and to assess the antibacterial potency of isolated Lactobacillus isolates. Following enrichment in De Man, Rogosa and Sharpe (MRS) broth, single colonies were isolated, and pure colonies were obtained by streaking on MRS agar. The 16S rRNA gene was amplified using polymerase chain reaction (PCR) to confirm the cultural positivity of all isolates. Additionally, the presence of plantaricin was verified by targeting the pln EF gene through PCR. Out of the 166 raw milk specimens acquired from cows, 153 (91.17%; CI: 86.98-95.76) were identified as positive for Lactobacillus through both culture and biochemical screening. Subsequently, 121 (72.89%; CI: 65.46-79.49) of the isolates were affirmed to harbour Lactobacillus through PCR analysis. Within this subset, 6 isolates (4.96%; CI: 1.84-10.48) were found to possess the plnEF gene. When exposed to Lactobacillus isolates, Salmonella Typhimurium and Salmonella enterica displayed an average maximum zone of inhibition with a diameter measuring 24mm. In contrast, Escherichia coli exhibited an average minimum zone of inhibition, featuring a diameter of 11mm. Additionally, the Lactobacillus isolates demonstrated inhibitory zones against Staphylococcus aureus, Klebsiella pneumoniae and Klebsiella oxytoca, measuring 14, 22 and 19mm, respectively. Lactic acid bacteria, particularly Lactobacilli, are plentiful in cow milk and possess broad-spectrum antibacterial properties.

The controversial case of a coastal Mesolithic tool: A geometric approach to the analysis of the Asturian pick

The Mesolithic period along the coast of the Cantabrian Region (Spain), known as the “Asturian,” is distinguished by the presence of shell middens and a particular lithic tool, the Asturian pick. Despite the tool’s archaeological significance, its technological and functional aspects have not been fully understood, resulting in ambiguous interpretations of its morphological relationships and utilitarian purposes. Our research aims to quantify and analyse the technological processes that have influenced the Asturian pick's form and investigate the selection criteria governing its morphology and choice of raw materials. A novel aspect of our approach is the use of digital methods, including photogrammetry and three-dimensional geometric morphometric analysis. We analysed a sample of Asturian picks, compared against a control group of different elements and raw material specimens. The findings corroborate the homogeneity and standardisation of the Asturian pick's design and unveil regional shape variations that correspond with the distinct raw materials available in each locality.

Rapid detection of major enterotoxin genes and antibiotic resistance of Staphylococcus aureus isolated from raw milk in the Yazd province, Iran.

Raw milk is a nutrient-rich food, but it may harbour harmful bacteria, such as enterotoxigenic Staphylococcus aureus (S. aureus), which can cause staphylococcal food poisoning. Antibiotic resistance of S. aureus in raw milk can increase the risk of such infections, particularly among susceptible individuals. This study aimed to investigate the prevalence of enterotoxin genes a, d, g, i and j and the antibiotic resistance of S. aureus isolated from raw milk samples. During a 6-month sampling period, 60 raw milk specimens were obtained from diverse locations in Yazd province, Iran. Antibiogram profiling was conducted via the disc diffusion method. In addition, staphylococcal enterotoxin (SE) genes a, d, g, i, and j were detected through real-time PCR analysis. Bacteriological assays confirmed the presence of S. aureus in 11 samples (18.3%). All isolates demonstrated 100% resistance to penicillin G but exhibited sensitivity to vancomycin, while resistance to other antibiotics ranged from 36.4% to 45.5%. The prevalence of enterotoxin genes in these strains showed variable distribution, with sea being the predominant SE (45.5%), followed by sed (36.4%), seg (18.2), sej and sei (9.1% each). This study discovered the presence of multiple enterotoxins in S. aureus strains obtained from raw milk samples. These strains also demonstrated resistance to a variety of antibiotics. Since enterotoxigenic S. aureus is known to cause human food poisoning, monitoring food hygiene practices, especially during raw milk production, is critical.

Mechanical behavior of recycled FDM printed parts from PETG in the circular economy

The aim of this paper was to observe the behavior of recycled 3D printed polyethylene terephthalate glycol (PETG) specimens and 3D printed raw specimens. In order to extrude the recycled grains into a filament, a Felfil evo filament extruder was used. The recycled filament was extruded from PETG at a temperature of 195°C and with a speed of 7 rpm according to the manufacturers’ requirements. Subsequently, different colors of the raw filament were printed on tensile specimens using Prusa i3 MK3S Original to compare the results between the recycled filament and the manufactured one. After printing the samples, the tensile tests were performed on the Zwick machine, with a capacity of 5KN. For the determination of the strain state in the test specimens, digital image correlation was used. A good correlation between the results was observed. Digital image correlation helped to better understand of the distribution of true principal strain in the recycled and raw specimens.

A rapid and easy-to-use spinal muscular atrophy screening tool based on primers with high specificity and amplification efficiency for SMN1 combined with single-stranded tag hybridization assay.

Spinal muscular atrophy (SMA) is an intractable neuromuscular disorder primarily caused by homozygous deletions in exon 7 of the SMN1 gene. Early diagnosis and prompt treatment of patients with SMA have a significant impact on prognosis, and several therapies have recently been developed. Current SMA screening tests require a significant turnaround time to identify patients with suspected SMA, due both to the interval between the birth of a newborn and the collection of blood for newborn mass screening and the difficulty in distinguishing between SMN1 and SMN2, a paralog gene that requires testing in specialized laboratories. The aim of this study was therefore to develop a novel SMA screening assay that can be rapidly performed in ordinary hospitals and clinics to overcome these issues. We designed over 100 combinations of forward and reverse primers with 3' ends targeting SMN1-specific sites around exon 7, and evaluated their specificity and amplification efficiency by quantitative PCR to identify the best primer pair. Furthermore, we performed a single-stranded tag hybridization assay after PCR. To evaluate the accuracy and practicality of the newly developed assay, we analyzed saliva specimens from five patients with SMA and two SMA carriers collected in an outpatient clinic and DNA specimens from three patients with SMA and four SMA carriers from a biobank, together with those from healthy individuals. DNA and raw saliva specimens from all patients with SMA demonstrated a biallelic loss of SMN1, whereas those from carriers and healthy individuals did not. The results of 50 independent experiments were consistent for all samples. The assay could be completed within one hour. This simple and convenient new screening tool has the potential to allow patients with SMA to receive disease-modifying therapies within a shorter timeframe.

Incorporating direct molecular diagnostics in management algorithms for nontuberculous mycobacteria: Is it high time?

Nontuberculous mycobacteria (NTM) are a group of acid-fast mycobacteria other than Mycobacterium tuberculosis complex (MTBC) that cause pulmonary disease that is similar to the disease caused by MTBC. International guidelines for the diagnosis of pulmonary NTM disease are rigid and have remained unchanged for nearly 2 decades. In this opinion piece, we provide a new perspective on the traditional criteria by suggesting a diagnostic algorithm that incorporates direct molecular identification of NTM performed on raw sputum specimens (using Sanger or targeted deep sequencing approaches, among others) paired with traditional culture methods. Our approach ensures a more rapid diagnosis of pulmonary NTM disease, thus, facilitating timeous clinical diagnosis, and prompt treatment initiation, where indicated, and leverages recent advances in novel molecular techniques into routine NTM identification practice.

Frequency of Vancomycin and Aminoglycoside Resistance Genes in Enterococcus spp. Isolated from Chicken Raw Meat Samples

Background: Enterococci are main normal microbial flora of both humans and animals and can survive in a diverse range of environments. These bacteria carry out aminoglycoside and vancomycin resistance genes and spread them in environment by many routs such as chicken meat products. The present study was aimed to determine the frequency of aminoglycoside and vancomycin resistant genes in Enterococcus species isolated from chicken meat specimens.
 Methods: A total of 250 chicken raw meat specimens was prepared from slaughterhouses at Zanjan province, cultured at BHI broth and incubated at 37°C for 24h. The positive cultures were sub-cultured in blood agar plates and grown colonies identified using phenotypical and biochemical tests. Antibiotic susceptibility was determined according to the Clinical and Laboratory Standards Institute (CLSI) standards and PCR assays were performed to detect vanA, vanB, aph (2")1c, aph (2")1b, aph (2")1d, ant(3'), aph(3')IIIa, ant(4')1a, ant(6') and aac(6') genes.
 Results: In total, 100 Enterococcus species isolated from 250 specimens and 35% of them belonged to E. faecalis and the others were E. faecium (65%). The prevalence of the vanA, vanB, aph (2")1c, aph (2")1b, aph (2")1d, ant(3'), aph(3')IIIa, ant(4')1a, ant(6') and aac(6') genes among the 100 Enterococcus species was 14%, 12%, 10%, 1%, 2%, 50%, 26%, 9%, 18% and 22%, respectively.
 Conclusion: The current study revealed that the rate of antimicrobial resistance genes to aminoglycosides and vancomycin was worrying and health measurements in meat products industries must be performed to prevent spread of antimicrobial resistance elements among bacteria.

Investigation of mode-I fracture behavior by essential work of fracture during the single-point incremental forming process

A promising technique for manufacturing low-thickness workpieces with complicated geometries is Incremental Sheet Forming (ISF). Due to its dieless process, ISF is a proper candidate for the production of workpieces at low rates or prototypes of the samples. The mechanical properties of the workpieces produced by ISF are a critical factor in determining their potential applications. Pyramid-shaped samples made of cold rolled steel (DC01) were produced using the single point incremental forming (SPIF) process in this study. To examine how the forming process affects mechanical properties, specimens were obtained from both raw and deformed surfaces. Subsequently, the specimens underwent tensile and fracture tests. The fracture toughness of the specimens was assessed using the essential work of fracture (EWF) technique. Through the use of incremental forming process, the tensile tests revealed a considerable improvement in both ultimate and yield tensile strength, with increases of 33.72% and 90.02%, respectively. However, the forming process led to a reduction of 86.64% in formability compared to the raw specimens. Fracture tests performed on the deformed specimens demonstrated a noteworthy reduction of 59.12% in the amount of energy needed for the initiation of crack growth, compared to the raw specimens. Additionally, we examined how the properties of deformed specimens are affected by the initial rolling direction of the sheets in this study. The study revealed that the mechanical properties and fracture characteristics of the material varied significantly along the transverse direction. The study utilized scanning electron microscopy (SEM) to analyze the fracture mechanisms and found that ductile fracture was the dominant mode of failure. The raw specimens demonstrated more ductile fractured surfaces, which corresponded to higher values of essential work of fracture (EWF).

RETRACTED ARTICLE: Helicobacter pylori strains isolated from raw poultry meat: frequency and molecular characteristics

Even though Helicobacter pylori (H. pylori) is a serious pathogen, its origin is unknown. Poultry (Chicken, Turkey, Quebec, Goose, and Ostrich) are consumed as a regular protein source by a large number of people across the world; therefore, sanitary ways of delivering poultry for food are important for global health. As a result, we looked at the distribution of the pathogenicity cagA, vacA, babA2, oipA, and iceA in H. pylori isolates in poultry meat, as well as their antimicrobial resistance. Wilkins Chalgren anaerobic bacterial medium was used to cultivate 320 raw poultry specimens. Disk diffusion and Multiplex-PCR were used to investigate antimicrobial resistance and genotyping patterns, separately. H. pylori was found in 20 of 320 (6.25%) raw poultry samples. The highest incidence of H. pylori was found in chicken raw meat (15%), whereas the fewest was found in Goose and Quebec (0.00%). Resistance to ampicillin (85%), tetracycline (85%), and amoxicillin (75%) were greatest in H. pylori isolates. The percentage of H. pylori isolates with a MAR value of more than 0.2 was 17/20 (85%). The most prevalent genotypes discovered were VacA s1a (75%), m1a (75%), s2 (70%) and m2 (65%), and cagA (60%). The most typically discovered genotype patterns were s1am1a (45%), s2m1a (45%), and s2m2 (30%). BabA2, OipA + , and OipA− genotypes were found in 40%, 30%, and 30% of the population. In summary, the poultry flesh was polluted by H. pylori, with the babA2, vacA, and cagA genotypes being more prevalent. The simultaneous occurrence of vacA, cagA, iceA, oipA, and babA2 genotypes in antibiotic-resistant H. pylori bacteria implies a serious public health concern about raw poultry eating. In the future, researchers should look into H. pylori's resistance to multiple antibacterial drugs in Iran.

Production of B4C Reinforced Composite Materials and Investigation of Their Bending Strength

In this study, AA2024 aluminum alloy was selected as the matrix material, while B4C was selected as the reinforcement material, and particle-reinforced Al-matrix composite materials were produced using the powder metallurgy method. Examinations were made to determine the effects of different reinforcement particle ratios and sintering temperatures on the mechanical properties of the AA2024 matrix composite materials that were produced. The powders were compressed in a metal mold at room temperature and a pressure of 525 MPa under a uniaxial press. The raw specimens that were obtained were sintered for 45 minutes at different temperatures. The produced composite materials were subjected to three-point bending tests and hardness measurements. Optical microscopy analysis was carried out for characterization. The results allowed us to draw a conclusion on how the reinforcement material in the produced specimens affected Al-matrix composite properties. It was determined that the B4C reinforcement added to the matrix increased the hardness values of the composites at all sintering temperatures, the highest bending strength was obtained in the composite with 10% B4C particle reinforcement, and in general, the B4C reinforcement was homogeneously dispersed in the matrix. Increased B4C reinforcement ratios resulted in higher hardness values in the composite materials.

P-042 Sperm Selection Based on Speed Using Rheotaxis in a Parallel Array of Microfluidic Apertures

Abstract Study question Does selecting human spermatozoa using a dynamic microfluidic system impact semen parameters and genomic characteristics? Summary answer Flow rate adjustment in a dynamic microfluidic device selects spermatozoa with superior DNA integrity. It also appears to select a higher proportion of Y-chromosome-bearing spermatozoa. What is known already Mammalian spermatozoa demonstrate rheotactic motion against the flow. This is important in order to overcome the fluid drag force in the female genital tract to reach the oocyte. Sperm processing methods have been developed based on these principles; more recently, static and dynamic microfluidic devices have been tested due to the association between high progressive motility and greater genomic integrity. These devices also appear to have an impact on sperm sex selection. Study design, size, duration Human ejaculates (n = 7) were evaluated and simultaneously processed by density gradient centrifugation (DGC) or a novel microfluidic sperm sorter (MFSS) with an adjustable flow rate inspired by the constriction of the uterotubal junction. Concentration, motility, morphology, and SCF were assessed and compared between raw, DGC-, and MFSS-processed specimens. To identify differences in the SCF and the proportion of X- and Y-spermatozoa, spermatozoa isolated at different flow rates (150, 250, 350, and 450 μl/h) were evaluated. Participants/materials, setting, methods Ejaculates were evaluated by standard semen analysis according to WHO 2021 criteria. Following complete liquefaction, 1 mL of sample was used for DGC, and 0.8 mL of semen was used for the prototype MFSS at 0.2 mL for each flow rate. SCF was assessed by TUNEL assay with a normal threshold of ≤ 15%. Fluorescent in situ hybridization (FISH) was performed using X- and Y-chromosome probes. Main results and the role of chance A total of 7 men (35.4±5 years) had the following semen parameters: volume of 3.3±2 mL, concentration of 76.7±33 x106/mL, 45.5±1% motility, and a normal morphology of 3.2±0%. When comparing the post-processing parameters between the two methods, DGC yielded a concentration of 49.9±25 x106/mL and MFSS yielded a reduced concentration of 4.5±5x106/mL (P<0.0001). DGC yielded 91.1±1% motility and normal morphology of 3.2±0.4%. Albeit at a cost of concentration, MFSS yielded spermatozoa with significantly higher motility (96.3±3%; P<0.0001) and a higher proportion with normal morphology (4.0±0.6%; P<0.0001). Moreover, the SCF of the raw sample was 9.4±2.0%; although the SCF was 8.1±3.6% with DGC, it was 4.5±2% (P<0.001) with MFSS. An analysis was performed within the different flow rates of the MFSS; a 250 μl/h flow rate yielded the highest recovery rate (42.0±6%; P<0.001), highest concentration (5.6±4 x106/mL; P<0.01), highest motility (97.0±2.2%; P<0.05), and a normal morphology rate (4.3±1%). The SCF for this flow rate was <3%. Surprisingly, we noticed that the proportion of Y-chromosome–bearing spermatozoa positively correlated to the flow rate, suggesting that there may be a subtle difference in the kinetics of male and female spermatozoa. Limitations, reasons for caution Although our novel MFSS platform is a promising technique, it is costly and requires specific expertise and training. This is a limited observation and requires integration of clinical outcomes to prove its benefits. Wider implications of the findings A microfluidic device with a controlled flow rate allowed the fine-tuned selection of spermatozoa with superior hydrodynamic and kinetic characteristics and a higher genomic integrity. Once automated, this device may help to select spermatozoa with greater embryo developmental competence and be useful to isolate spermatozoa of the desired sex. Trial registration number N/A

Post-Ultraviolet-Curing Process Effects on Low-Velocity Impact Response of 3D Printed Polylactic Acid Parts

In this study, polylactic acid (PLA) parts produced with the 3D fused deposition modelling (FDM) technique were cured with ultraviolet irradiation (post-UV-curing) after production, and the low-velocity impact behaviour of the parts was experimentally investigated. Accordingly, PLA parts were subjected to post-UV-curing at 15-, 30-, 45-, and 60-minute periods. The impact behaviour of the specimens produced with production parameters of 200 °C printing temperature, 0.2 mm layer thickness, 50 mm/s printing speed, 100% infill rate, and 45° raster angle was compared with the raw specimens after the post-UV-curing process was applied. As a result of the impact tests, peak force, peak displacement, peak energy, and puncture energy values were obtained from the force-displacement graphs. It has been revealed that the post-UV-curing implementation increases the peak force values of PLA specimens and decreases the displacement values compared to the raw specimens. All specimens' impact behaviour improves with the post-UV-curing process; however, a decreasing trend is entered after 30 min.

PENGARUH PERLAKUAN MEDIA PENDINGIN NaCl TERHADAP PELAPISAN PERMUKAAN SURFACE TREATMENT PADA REL KERETA API UIC R54

This study aims to understand and determine how effective the addition of NaCl in the quenching surface treatment media for the UIC R54 railroad. This study applies a method that refers to the theory of surface treatment. First, the surface treatment process is carried out on the surface of the rail specimen. The cooling medium used in the surface treatment process is a mixture of NaCl of 200-800gr NaCl at intervals of 200gr with 1000ml of water. Furthermore, observations of the microstructure and measurement of the hardness value on the surface of the rail specimen were carried out. The average hardness value for raw material specimens is 283.52 BHN. The highest hardness value in specimens that have been surface treated is 346.36 BHN in the treatment of adding 60% NaCl to the quenching medium. In raw material specimens, the phase formed is dominated by ferrite and pearlite. Meanwhile, the phase formed after the surface treatment process is martensite. From these results it can be concluded that a mixture of 60% NaCl with water used as a cooling medium is effective in increasing the hardness value of the rail.

Experimental study on coal seam permeability enhancement and CO2 permeability caused by supercritical CO2

Permeability is one of the most important parameters for characterizing fluid flow and production from reservoirs. In this paper, experimental studies on the percolation, permeability, and adsorption of supercritical CO2 in coal seams were carried out, taking into account the effects of injection pressure and temperature, comparing the changes in longitudinal wave velocity of specimens before and after the tests, and analyzing the permeability effect of supercritical CO2 on raw coal specimens. The test results showed that when the volume stress was 36 MPa, the permeability of supercritical CO2 in coal increased by 93%, on average, compared with that of CO2. The modified D-R model was used to fit the adsorption data, and it was found that the excess adsorption capacity of supercritical CO2 by coal decreased with increased pressure, with a maximum value of approximately 8 MPa. When the temperature increased by 10°C, the adsorption capacity decreased by 8.3%, on average. In the subcritical CO2 state, the trend of excess CO2 adsorption in coal was consistent with that of absolute adsorption, which was 16% higher than that of excess adsorption, on average. After the action of supercritical CO2, the propagation velocity of the longitudinal wave in the sample decreased significantly, indicating that supercritical CO2 can effectively promote the development of pores and fractures in the coal sample, with an obvious anti-reflection effect on the coal seam and the best permeability enhancement effect at 35°C.

Reactivity of raw, pyroprocessed and GGBS-blended alum sludge (AS) waste for sustainable cement production

This paper investigates AS waste to produce a construction binder of low environmental impact. It studies the reactivity of AS so that it can be used instead of traditional (higher impact) binders. Currently, most construction binders are Portland cement (PC) based, hence carrying a major environmental impact. Significant impact can be offset by using wastes as binders. Alum sludge (AS) waste is massively produced in drinking water plants, and its primary component is aluminium hydroxide (Al(OH)3). Both the raw and the calcined AS exhibit pozzolanic activity measured by the Chapelle test. The organic matter in raw AS inhibits pozzolanic reaction and hydrate formation, hence the raw AS specimens display low strength. Calcination removed the organic matter and induced the dehydroxylation of Al tetrahedra thereby increasing the pozzolanic activity of AS. The AS burned at 450 and 600 °C shows excessive reactivity which results in a flash set. However, at 800 °C, some amorphous Al(OH)3 transforms into semi-amorphous γ-Al2O3 avoiding flash set and allowing handling while maintaining significant reactivity that yields substantial strength. At 1000 °C, the conversion of amorphous Al(OH)3 into inert corundum significantly lowers reactivity. Therefore, pyroprocessing AS at 800 °C produces material of high reactivity: abundant calcium aluminate hydrates were evident in the pastes due to pozzolanic reaction and secondary hydration involving CO32− ions. Replacing 50% 800°C-AS with GGBS enhances strength and avoids strength reduction (caused by the conversion of carbonate AFm phases to Si-rich AFm phases, possibly stratlingite). A blend of 800°C-calcined AS and GGBS, in a lime or PC system, renders workable setting times and a high ultimate strength. Calcination is the key parameter affecting AS as binder replacement. When incorporated into lime or PC systems, improper calcination may cause problems such as flash setting and a strength reduction.

Cooking methods effectively alter perfluoroalkyl substances and nutrients in cultured and wild bullfrogs

The ubiquitous distribution of perfluoroalkyl substances (PFASs) poses a threat to the health of aquatic organisms and humans. Bullfrogs are considered a popular aquatic food product in South China, providing high protein and tasty cuisine; however bullfrogs have been shown to contain significant concentrations of PFASs. However, the risk-benefit ratios of PFASs and nutrient contents in cooked bullfrogs are not well understood. PFASs and nutrients were investigated in raw and cooked specimens of cultured and wild bullfrogs in this study. Novel PFASs showed higher detection levels and accumulation in wild bullfrogs than in cultured bullfrogs. Potential factors such as fat and fatty acid ratio affected PFASs accumulation in different tissues and by different cooking methods of bullfrogs. All cooking methods can reduce PFASs in edible tissues while significantly enhancing the nutritive value index (NVI) compared to raw bullfrogs. Steaming was the most effective way to reduce PFASs (rate of reduction was over 66%) and resulted in a lower risk of contributing to arteriosclerosis than other cooking methods assessed by atherogenicity index (AI) values. Cultured bullfrogs instead of wild bullfrogs were recommended for human consumption, and steaming was regarded as a better cooking method in terms of risk-benefit concerns. Overall, this work provides quantitative analysis of cooking methods that alter PFASs and nutrients in bullfrogs.

Production of AA2024-Matrix B4C-SiC- and B4C-Y2O3-Particle-Reinforced Composites by Powder Metallurgy and Investigation of Their Mechanical Properties

In this study, it was aimed to produce Al-matrix composite materials with B4C-SiC and B4C-Y2O3 particle reinforcement using the Powder Metallurgy (PM) method. In the composites in which the reinforcement materials were used at different particle sizes and ratios, AA2024 powders were selected as the matrix material. The powders were homogeneously mixed and compacted at room temperature under a pressure of 525 MPa. The raw specimens were sintered by keeping them at different temperatures for 45 minutes. The composite materials were subjected to wear tests, and their hardness and density values were investigated. In the study, the effects of reinforcement materials added to the matrix at different particle sizes and ratios on wear resistance, hardness, and density at different temperatures were examined.