Sample Zone Research Articles

Influence of plasma electrolytic oxidation coating on reducing the corrosion rate of dissimilar FSW joint between AA5052 and AZ31 alloys by minimizing effect of different galvanic couple types

This study investigated the different aspects of macro/micro-galvanic corrosion behavior of plasma electrolytic oxidation coating (PEO) applied on a dissimilar joint. In this regard, AA5052 and AZ31 were joined by friction stir welding. Then, the dissimilar joints were simultaneously coated with different electrolyte conductivities and current densities through PEO process. Despite of coated samples, the stir zone (SZ) of uncoated sample was severely corroded due to macro-galvanic couple (AA5052/AZ31) and micro-galvanic couple (intermetallic compound/surrounding matrix). In the optimal coated sample (CD-350), the corrosion current density of SZ compared with uncoated sample dropped from 8.18 × 10−4 to 1.69 × 10−5 A/cm2. The ratio between corrosion current density of SZ and that of uncoupled anode that is demonstrating the severity of galvanic effect; was less than 5 (icorr SZ/iuncoupled anode = 4.17), therefore the various regions were totally compatible due to the effect of PEO coating on reducing different galvanic couple types. The corrosion rates for both heat-affected zone and base metal on each side of the coated samples were nearly identical, indicating the independence of the coating quality and properties from substrate microstructure. The findings revealed that rising electrolyte conductivity and current density led to the growth of coating thickness while the number of microspores decreased and their average diameter increased. Meanwhile, α-Al2O3, γ-Al2O3, and SiO2 amorphous formed on AA5052 side; and MgO, Mg2SiO4, and MgF2 on AZ31 side during coting process.

Scale-dependent behavior of microstructure characteristics of laser powder bed fused TiB2/AlSi10Mg composite

The pre-alloyed TiB2/AlSi10Mg composite, a new high-strength aluminum alloy developed for laser powder bed fusion (LPBF) technology, offers promising applications in lightweight and multi-scaled structures. However, thermal behavior during LPBF is markedly scale-dependent, leading to microstructural variations that significantly affect the load-bearing capacity of multi-scaled structures. Therefore, this study systematically investigates the scale-dependent behavior of microstructure characteristics of this composite. Utilizing a hatching scanning strategy, it was found that the marginal zones of samples are predominantly composed of coarse Al cell and Al grain structures, contrasting with the fine microstructures in the central zones. With increasing structure scale, cell and grain structures in both the marginal and central zones become more refined, with cell sizes reducing by 49 %–72 % (∼3.02 µm → 0.86–1.55 µm). Particularly, the minimum-scaled structures also feature broken eutectic Si particles and nanopores. The essence is primarily due to the low heat dissipation with higher peak temperature and longer duration time at high temperatures in both the small-scale structures and marginal zones. Additionally, smaller structures correlate with reduced microhardness and tensile strength, accompanied by the “softening” of the marginal zones. The strength of the minimum-scaled structure is only half that of the standard sample. Our findings suggest a scale threshold of 2.0 mm for researching scale effect. Encouragingly, incorporating additional contour scanning significantly counteracts the adverse influence of the scale effect. Owing to the combined influence of extended inter-layer time and laser remelting, all samples demonstrate a distinctly refined microstructure. This results in consistently high levels of microhardness and strength, with the “hardening” of the marginal zones. Eventually, the relationship between mechanical properties and microstructure sizes is established. This study provides valuable insights into the innovative designs and engineering applications of multi-scaled structures in LPBF using various materials.

Multiplexed colorimetric assay of antioxidants in wines with paper-based sensors fabricated by pen plotting

This work reports the development of low-cost and rapid multiplexed colorimetric assay of antioxidants (total phenolics, antioxidant capacity, flavonoids and anthocyanins) in wines at daisy-shaped fluidic paper-based analytical devices (PADs). The desired fluidic patterns were formed on paper by pen drawing and colorimetric reagents were immobilized at the 6 peripheral test zones. The sample was added at the central sample zone, migrated to the test zones and reacted with the immobilized reagents producing characteristic colors that were captured and analyzed. The paper-based approach was applied to the analysis of several wine samples and the results were statistically correlated to standard solution-based colorimetric assays, indicating that it could be reliably used for ranking wines according to their antioxidants content. In addition, the paper-based analytical methodology is simple, instrument-free, portable, cost-effective, rapid and environment friendly.

Work environment adversity and non-communicable Disease risk among drivers working for application-based-cab-aggregators in an Indian metropolis

BackgroundBengaluru, a metropolis in Southern India, is one of the largest markets for cab aggregator companies. Drivers working for these companies play a vital role in urban transportation but unlike other drivers, their work pattern is stressful, which could increase their proneness to NCD risk factors. Understanding associations between work environment adversity and NCD risk factors among these drivers will help to plan specific health promotion and NCD prevention programs including provision of basic occupational health services.ObjectivesThe study aims to test for an association between work environment adversity and selected Non-communicable Disease (NCD) risk factors among Application Cab Aggregator drivers in Bengaluru city and to estimate the prevalence of selected NCD risk factors among the ABCA drivers.MethodologyThis cross-sectional study was conducted in Bengaluru city among 340 eligible and consenting ABCA drivers with at least one-year experience. Drivers were recruited through a multi-stage sampling procedure and time-period sampling, from transportation and leisure zones in the city. Data was collected through interviews using specifically developed semi-structured tools to assess work environment adversity and NCD risk factors. Prevalence of NCD risk factors is presented per 100 drivers with 95% confidence intervals. Multivariate Logistic regression analysis was conducted to quantify the strength of the association between work environment adversity categories and NCD risk factors. Ethical clearance was obtained from the NIMHANS Ethics Committee.ResultsNearly 97% of the 340 drivers reported having one or more NCD risk factors. Working more than 5 days a week, more than 7 + hours a day, staying away from family, and working night shifts were closely associated with higher risk for NCD risk factors among ABCA drivers. Drivers with work environment adversity scores between 5 and 10 were associated with higher odds of Physical Inactivity (OR = 3.1), Unhealthy diets (OR = 1.62), and Tobacco Use (OR = 3.06).ConclusionThe study highlights the association between work environment adversity and NCD risk factors and indicates a dire need for NCD prevention programs, basic occupational health services, and social security provisions for ABCA cab drivers.

Scaling of damage mechanism for additively manufactured alloys at very high cycle fatigue

A comparative analysis of fracture mechanisms in high- and very high- cycle fatigue (HCF, VHCF) regimes was carried out based on the results of multifractal analysis of the fracture surfaces of additively manufactured 316L stainless steel samples. In terms of scale invariants, the morphology of fracture surfaces in HCF and VHCF regimes inside and outside the fine granular area is shown. The analysis demonstrated that chaotic patterns of relief formation prevail in the crack initiation zone of VHCF samples. However, there is a self-similar relief with a pronounced correlation in the crack propagation area. The relief of the crack growth areas for HCF and VHCF samples are similar to each other.

A Foldable Thermoplastic Microdevice Integrating Isothermal Amplification and Schiff-Reaction-Based Colorimetric Assay for the Detection of Infectious Pathogens

In this study, we introduce a plastic-based foldable microdevice that integrates loop-mediated isothermal amplification (LAMP) and a colorimetric assay based on the Schiff reaction to detect the genes of infectious bacteria. The device comprises two sides: a sample zone containing amplification chambers and a detection zone for the colorimetric assay. The detection zone contains poly(methyl methacrylate) structures for transferring the colorimetric reagent-soaked glass micro-fiber paper into the sample chambers. Specific genes of Staphylococcus aureus (S. aureus) and Streptococcus pneumoniae (S. pneumoniae), the most common bacterial infection causes, were amplified by LAMP assay. The S. aureus gene was detected up to 10 fg/μL and the S. pneumoniae gene up to 0.1 pg/μL. The amplified target genes were visually identified using a colorimetric assay with Schiff’s reagent, which showed clear color discrimination through a reaction with aldehyde groups derived from the DNA in the amplicons. The introduced method, integrating amplification and detection processes in a single device, is expected to be utilized in point-of-care testing analysis for the simple and rapid detection of infectious pathogens.

On a Spectral Method for β-particle Bound Excitation Collisions in Kilonovae

The interaction of β-particles with the weakly ionized plasma background is an important mechanism for powering the kilonova (KN) transient signal from neutron star mergers. For this purpose, we present an implementation of the approximate fast-particle collision kernel, described by Inokuti following the seminal formulation of Bethe, in a spectral solver of the Vlasov–Maxwell–Boltzmann equation. In particular, we expand the fast-particle plane-wave atomic excitation kernel into coefficients of the Hermite basis, and derive the relevant discrete spectral system. In this fast-particle limit, the approach permits the direct use of atomic data, including optical oscillator strengths, normally applied to photon–matter interaction. The resulting spectral matrix is implemented in the MASS-APP spectral solver framework, in a way that avoids full matrix storage per spatial zone. We numerically verify aspects of the matrix construction, and present a proof-of-principle 3D simulation of a 2D axisymmetric KN ejecta snapshot. Our preliminary numerical results indicate that a reasonable choice of Hermite basis parameters for β-particles in the KN is a bulk velocity parameter u = 0, a thermal velocity parameter α = 0.5c, and a 9 × 9 × 9 mode velocity basis set (Hermite orders of 0–8 in each dimension). For interior-ejecta sample zones, we estimate that the ratio of thermalization from large-angle (≳2.°5) bound excitation scattering to total thermalization is ∼0.002–0.003.

РАЗРАБОТКА МЕТОДА ИДЕНТИФИКАЦИИ И ОПРЕДЕЛЕНИЕ ЭФИРНОГО МАСЛА В ПОБЕГАХ ТУИ ЗАПАДНОЙ (THUJA OCCIDENTALIS)

The purpose of the study is to develop methods for identifying terpenoids and assessing the quantitative content of essential oil in the shoots of western thuja (Thuja occidentalis). The object of the study was samples of thuja occidentalis shoots. The raw materials were used fresh. To carry out qualitative reactions, well-known methods were selected that are most often used in the analysis of essential oil raw materials. Identification of essential oil components was carried out by TLC on Silufol plates. A solution of α-pinene was used as a standard. The quantitative content of essential oil in the raw materials was determined by steam distillation in accordance with the GPM method 1.5.3.00010.15 Determination of the content of essential oil in medicinal plant raw materials and medicinal herbal preparations. The authors proposed qualitative reactions for identifying terpenoids in raw materials, which can be used to form the “Authenticity” section for a new type of raw material - thuja occidentalis shoots. α-pinene was identified by TLC. A quantitative assessment of the essential oil content in raw materials was carried out. Qualitative reactions were experimentally selected to confirm the presence of terpenoids in alcoholic extracts from thuja occidentalis shoots, as well as for unsaturated compounds in essential oil obtained by steam distillation. Using TLC, α-pinene was identified in the analyzed samples. The presence of additional 8 adsorption zones in the essential oil samples was also revealed. Assessment of the quantitative content of essential oil in raw materials, carried out according to method 2 OFS.1.5.3.00010.15 “Determination of the content of essential oil in medicinal plant raw materials and medicinal herbal preparations.” The data obtained during the experiment allows us to recommend the inclusion of an essential oil content of at least 2.84% in the quality indicators of western thuja shoots.

Green synthesis of metal nanoparticles from Codium macroalgae for wastewater pollutants removal by adsorption

AbstractAlgae have adsorption properties and reducing agents due to their rich content. In this study, palladium nanoparticles (Pd NP), platinum nanoparticles (Pt NP), and iron oxide nanoparticles (Fe3O4 NP) were prepared from Codium macroalgae using green synthesis. The structure of the synthesized nanoparticles was elucidated by X‐ray diffractometry, Fourier transforms infrared spectroscopy, Brunauer–Emmett–Teller analysis, transmission electron microscopy, ultraviolet‐visible spectroscopy and scanning electron microscopy‐energy dispersive X‐ray spectrometry and their use as nanoadsorbents for the removal of pollutants from aqueous media was investigated in detail. Naproxen (NPX), an anti‐inflammatory drug, and the dyes methylene blue (MB) and cresol red (CR) were selected as pollutants for this study. Batch adsorption experiments were conducted using both real wastewater obtained from the Organised Industrial Zone of Isparta Province and synthetic water samples prepared with tap water from Burdur Province and pure water. Under optimum adsorption conditions, Pd NP showed significant efficiency in the real wastewater sample, with an adsorption capacity of 37.19 and 50.03 mg g–1 for CR and NPX, respectively, within 150 min. In comparison, Pt NP showed an adsorption capacity of 40.01 mg g–1 for MB within the same timeframe. These findings indicate that while Pd NP showed the highest adsorption capacity for both CR and NPX, Pt NP showed the highest adsorption capacity for MB. The Langmuir model and the pseudo‐second‐order equation were more suitable to describe the adsorption behavior of CR, MB, and NPX. In addition, studies on the desorption and reusability of the nanoadsorbents were carried out under the same optimum experimental conditions.

Expression of Toll-like receptors in oral squamous cell carcinoma.

Almost 380,000 new cases of oral cancer were reported worldwide in 2020. Oral squamous cell carcinoma (OSCC) accounts for 90% of all types of oral cancers. Emerging studies have shown association of Toll-like receptors (TLRs) in carcinogenesis. The present study aimed to investigate the expression levels and tissue localization of TRL1 to TRL10 and NF-κB between OSCC and healthy oral mucosa, as well as effect of Candida colonization in TRL expression in OSCC. Full thickness biopsies and microbial samples from 30 newly diagnosed primary OSCC patients and 26 health controls were collected. The expression of TLR1 to TLR10 and NF-κB was analyzed by immunohistochemistry. Microbial samples were collected from oral mucosa to detect Candida. OSCC epithelium showed lower staining intensity of TRL1, TRL2 TRL5, and TRL8 as compared to healthy controls. Similarly, staining intensity of TRL3, TRL4, TRL7, and TRL8 were significantly decreased in basement membrane (BM) zone. Likewise, OSCC endothelium showed lower staining intensity of TLR4, TLR7 and TLR8. Expression of NF-κB was significantly stronger in normal healthy tissue compared to OSCC sample. Positive correlation was found between the expression of NF-κB, TRL9 and TRL10 in basal layer of the infiltrative zone OSCC samples (P = 0.04 and P = 0.002, respectively). Significant increase in TRL4 was seen in BM zone of sample colonized with Candida (P = 0.01). According to the limited number of samples, our data indicates downregulation of TLRs and NF-κB in OSCC, and upregulation of TLR4 expression with presence of Candida.

The influence of carbon dioxide concentration on carbonation behavior in cement paste

Accelerated carbonation is the main method of simulating carbonation in the laboratory, but there are significant differences in the CO2 concentrations adopted for accelerated carbonation testing among the various standards currently. In this work, X-ray imaging technology was used to study the distribution of the carbonation zone in samples at different CO2 concentrations and used for imaging, which was followed by quantitative analyses of the carbonation profile and the material compositions of the entire carbonation zone in combination with thermogravimetric analysis (TGA) and 29Si nuclear magnetic resonance (29Si NMR) analyses. The results showed that the carbonation profiles of cement paste were similar under 3% and 10% concentration, with the front line of carbonation developing parallel to the soffit of the sample. However, when the concentration was increased to 20%, the carbonation profile at partial carbonation zone could be changed due to shrinkage cracking. In addition, the compositions of the complete carbonation zone under different concentrations were similar, and the development of this zone followed Fick's law.

Experimental study on mechanical properties and evolution of fracture failure of granite considering initial temperature damage and prefabricated fissure length

With the increasing mining depth of deep mineral resources, the influence of high temperature on the fracture failure of surrounding rock with fissures becomes increasingly serious. To investigate the fracture mechanical properties and the evolutionary characteristics of fracture process of fissured rock experiencing initial temperature damage, the three-point bending experiment was conducted on the small sized granite samples with different initial damaging temperatures and prefabricated fissure lengths by applying a μTS mesoscopic testing system. Based on the digital image correlation methods, the evolution of fracture process zone of sample was revealed. Moreover, the macroscopic fracture failure of sample was predicted by the evolution of time-varying acoustic emission b-value. The results show that with the increase of initial damaging temperature and prefabricated fissure length, the peak load of granite sample has a decreasing trend and the fracture characteristics of sample experiencing initial temperature damage gradually transform from brittleness fracture to ductility fracture, resulting in a decrease in the fracture toughness of sample. The crack tip opening displacement, the critical opening displacement and the length of fracture process zone of sample all show an increasing trend. The time interval from the time when time-varying acoustic emission b-value continues to decline to the appearance moment of macroscopic cracks is selected as the warning time of fracture failure of sample, which can conclude that the warning time increases with increasing the initial damaging temperature and prefabricated fissure length, indicating an increase in ductility and a reduction in failure suddenness of sample.

Isolation and characterization of a newly discovered plant growth-promoting endophytic fungal strain from the genus Talaromyces

In the Kandi zone of Punjab, India, root and rhizospheric soil samples were collected from the local vegetation near the Shivalik mountain foothills. Fifteen fungal colonies exhibiting distinct cultural morphology on Potato Dextrose Agar (PDA) plates were selected for plant–microbe interaction studies. Among these, the isolate HNB9 was identified as a nonpathogenic root colonizer. Morphological and molecular analyses confirmed HNB9 as Talaromyces albobiverticillius, characterized by the secretion of a red pigment as a secondary metabolite. Plants colonized with T. albobiverticillius HNB9 exhibited enhanced growth, manifesting in increased shoot and root length compared to untreated controls. This study unveiled the first evidence that a species from the Talaromyces genus, specifically T. albobiverticillius, possesses dual capabilities of root colonization and plant growth promotion. Moreover, HNB9 demonstrated the production of plant growth-regulating compounds like Indole Acetic Acid (IAA) and proficient solubilization of crucial nutrients (Phosphorous, Zinc, and Silica) through plate culture methods. This finding represents a significant contribution to the understanding of root-colonizing fungi with plant growth-promoting attributes, challenging the existing knowledge gap within the Talaromyces genus.

Isotachophoresis with Oscillating Sample Zones to Control the Spatial Overlap of Co-focused Species.

Microfluidic isotachophoresis (ITP) is a powerful technique that can significantly increase the reaction rate of homogeneous chemical reactions by cofocusing reactants in a narrow sample zone. Correspondingly, ITP has been utilized to reduce the reaction time in various bioanalytical assays. However, in conventional ITP, it is hardly possible to control the reaction rate in real time, i.e., speeding up or slowing down a reaction on demand. Here, we experimentally demonstrate a new mode of ITP that allows the spatial overlap of two ITP zones to be precisely controlled over time, which is a crucial first step toward controlling reaction rates. Two nonreactive samples are initially focused and separated by a spacer using a DC electric field. By superimposing an oscillating field component with sufficiently high amplitude on the DC field, the spatial overlap of their concentration profiles is temporarily increased due to electromigration dispersion. The time-average of this overlap can be precisely controlled by varying the frequency and amplitude of the oscillation. We suggest that this scheme can be transferred to chemical reactions between ionic species with sufficiently different electrophoretic mobilities. Tuning the parameters of the oscillatory electric field should allow direct control of the corresponding reaction rate.

Improving the processability and grain structures of additively manufactured Al-Fe-Cu-xZr alloy: Experiment and high-fidelity simulation

Additive manufacturing (AM) offers significant advantages over conventional manufacturing techniques in processing Al alloys, however, high-strength Al alloys produced by AM commonly encounter a few challenges including poor processability and undesirable microstructures with coarse columnar grains and even micro-cracks, leading to poor mechanical properties of the resultant Al alloys. Here, we demonstrate that these issues can be largely resolved by micro-alloying of Zr element in the Al-based alloys. In this study, a series of novel Al-1Fe-0.6Cu-xZr alloys with different content of Zr (x=0.3, 0.6, 0.8, 1.3 at%) are designed and then subjected to laser powder bed fusion (LPBF). It is found that, with increasing Zr content, the processability of Al alloys is significantly improved, as evidenced by the gradual reduction of melt splashing and defects (including pores, balling, necking and discontinuity) during LPBF, which eventually leads to decrease of surface roughness and improvement of processability. High-fidelity simulation reveals that the processability is closely related to the melt velocity gradient (MVG) in melt pools. Increasing Zr content results in a more uniform distribution of MVG and decreased Marangoni convection, which favors the stability of melt pool and good processability. On the other hand, Zr content also plays an important role in microstructure. Although the four LPBF Al alloys all exhibit notably heterogeneous structures with alternate distribution of coarse grain zones (CGZs) and fine grain zones (FGZs) in the whole samples, with increasing Zr content, the coarse columnar grain structure in CGZs is suppressed and transforms to the fine equiaxial grain structure. The occurrence of columnar-to-equiaxed transition (CET) is attributed to the decreased ratio between temperature gradient (G) and solidification rate (R) at the solid-liquid interface with increasing Zr content. In addition, the increase in Zr content also leads to a gradual refinement of the grain size in both CGZs and FGZs due to the increased cooling rate. Beneficial from the good processability and fully refined equiaxial gain structure, nearly full-dense and high-strength Al alloys with 0.8 and 1.3 at% Zr are successfully fabricated, which show a good combination of high strength and ductility. The findings in this work provide a guild for design of novel Al alloys with good processability and advanced mechanical properties for additive manufacturing.

ЭКСПЕРИМЕНТАЛЬНАЯ ОЦЕНКА ИЗНОСОСТОЙКОСТИ ПОЛИМЕРНЫХ МАТЕРИАЛОВ, ПРИМЕНЯЕМЫХ В ПОРШНЕВОМ КОМПРЕССОРНОМ ОБОРУДОВАНИИ

A new method is proposed for assessing the wear resistance of polymer materials according to the “finger — disk” friction scheme. It involves changing the geometry of the friction zone of polymer samples — the “finger” sphere is replaced by a truncated cone. The developed method is tested on samples of polyetheretherketone (PEEK) and polymer composite materials (PCM) based on polytetrafluoroethylene (PTFE, fluoroplast-4), in particular, obtained after laser ablation with the addition of carbon fibers. The relevance lies in simplifying the manufacture of samples, as well as the possibility of quickly changing the geometric parameters of their working part, which expands the scope of the method with respect to the latest polymer materials and composites based on them. The practical significance of the results is confirmed by their use at such enterprises as JSC “Grodno Azot” and JSC “Grodno Mechanical Plant”, which serially produce tribotechnical PCM.

Impact of Hurricanes, Tropical Storms, and Coastal Extratropical Storms on Indoor Air VOC Concentrations

AbstractUnderstanding vapor intrusion (VI) temporal variability is key for the design of sampling strategies intended to assess reasonable maximum exposure of indoor air concentrations of volatile organic compounds (VOCs) as well as risk evaluation and mitigation planning. VI temporal variability has previously been shown to be dependent on the complex interactions of multiple independent variables—meteorological, hydrogeological, and human behavioral. Several meteorological variables, including barometric pressure, wind speed, and rainfall, are linked during tropical and extratropical storm events. High‐frequency meteorological and indoor VOC data from a series of seven tropical storms and four extratropical storms were collected at a single industrial building with multiple heating, ventilation, and air conditioning (HVAC) zones. The storms and sampling zones showed a variety of effects on trichloroethylene (TCE) concentrations in indoor air. In one zone (supply room), increases in TCE concentrations often, but not always, closely coincided with decreasing barometric pressure, sustained wind speeds over 32 km/h (20 mph), and differential pressures indicating subslab to indoor flow. A second zone, in a restroom, did not show a consistent pattern of temporal correlation between meteorological factors and indoor air concentrations. While peak indoor air concentrations may be associated with the passage of cyclonic storms at some sampling locations, this does not appear to be generalizable to all sampling locations. The observed increase in indoor air concentration potentially attributable to these storms is typically less than an order of magnitude and the duration ranges from a day to a week.

Effect of Dispersing In Situ Al-Cu Intermetallic Compounds on Joint Strength in Friction Stir Welding of AA3003-H18 Sheets

In this study, friction stir welding (FSW) was employed to join AA3003-H18 sheets by incorporating in situ Al-Cu intermetallic compounds within the stir zone. The FSW process was carried out under three distinct conditions: (I) without applying powder, (II) by introducing Cu powder, and (III) by incorporating Cu-Al mixed powder (50 vol.% Cu, 50 vol.% Al). The powder was embedded into the gap between two sheets. Subsequently, two-pass FSW, involving both forward and backward movements, was conducted with a rotational speed of 1200 rpm and traverse speed of 100 mm/min across all three experimental conditions. In the second and third conditions, the formation of in situ intermetallic compounds occurred through a solid-state reaction between Cu particles and Al within the stir zone. Examination of the stir zone through optical and electron microscopic studies revealed that the utilization of Cu-Al mixed powder resulted in finer and more uniformly distributed Cu clusters and Al-Cu intermetallics than samples welded with Cu powder alone. Notably, the stir zone of samples incorporating Cu-Al mixed powder exhibited finely dispersed, completely gray Al-Cu intermetallic particles, whereas those with only Cu powder displayed predominantly coarse core-shell particles in the microstructure. The introduction of Cu-Al mixed powder during FSW resulted in a stir zone with an average hardness of 74 HB, showing a 14% increase compared to the cases where Cu powder alone was added (65 HB). Tensile tests, conducted in both transverse and longitudinal directions on the FSWed samples, did not exhibit a consistent trend across the three mentioned conditions. Transverse tensile strength consistently ranged between 107 and 110 MPa, with joint efficiency varying from 52% to 54%. However, the longitudinal tensile strength of the joint with added Cu-Al mixed powder (158 MPa) surpassed those welded with Cu powder alone (134 MPa).

Paper-based electrochemical immunosensor for highly sensitive detection of chicken anemia virus

Chicken anemia virus (CAV) is one of the primary causes of morbidity and mortality in young chickens. Given the importance of timely detection for maintaining livestock quality, there is a pressing need for rapid and field-deployable diagnostic tools. This study introduces a highly sensitive paper-based electrochemical immunosensor (PEI) for the detection of the 60 amino acid N-terminally truncated viral protein 1 (Δ60VP1), a derivative of the CAV capsid (VP1). A custom antibody was produced for precise immunoassay detection, with results obtainable within 30 min using Square Wave Voltammetry (SWV). The underlying mechanism involves an immunocomplex in the sample zone that hinders the electron transfer of redox species, thereby reducing the current signal in proportion to the Δ60VP1 concentration. Under optimal conditions, the detection linearity for Δ60VP1 ranged from 80 to 2500 ng/mL, with a limit of detection (LoD) of 25 ng/mL. This device was then successfully applied to detect VP1 in 29 chicken serum samples, achieving 91.6% sensitivity and 94.1% selectivity. In conclusion, the PEI device presents a promising solution for rapid, sensitive, and disposable detection of chicken pathogens, potentially revolutionizing productivity and quality assurance in chicken farming.

Developing lateral-flow devices for the fast and cheap detection of SARS-cov-2 in wastewater: a potential tool to monitoring local virus outbreaks by wastewater based epidemiology

The SARS-CoV-2 virus generates severe respiratory tract complications such as pneumonia and bronchitis and mild symptoms such as common colds or asymptomatic conditions. The SARS-CoV-2 presence in human feces and in treated/untreated wastewater suggests a transmission way that could generate local outbreaks, in addition to other type of diseases or disorders. Based on the above, in this work it was proposed the assembly of a lateral flow device (LFD) to determine the SARS-CoV-2 presence in wastewater samples. In the LFD a wastewater sample capillary flowed through four membranes: sample zone, conjugate delivery zone, reaction zone and the reactive adsorption zone. The virus amplification was achieved by the novel reverse transcription loop-mediated isothermal amplification (RT-LAMP) at the sampling point. The membranes preconditioning processes and the use of membranes with 5-20 nm porous size increased the capillary flow rate and it was promoted the interaction of the gen of SARS-CoV-2 with the capture agents in the reactive adsorption zone. Additionally, the sensibility of the detection was improved using several methods for the immobilization of the capture agents on the reaction zone membrane. The RT-LAMP method combined with the assembled LFD allowed an efficient SARS-CoV-2 detection at the sampling point in a simple way, cheap and fast compared to conventional and expensive RT-PCR.