Search Results (3,531)

This conceptual article introduces knowledge-centric recruitment (KCR) as a distinct dynamic capability that reframes recruitment and post-hire socialization as strategic knowledge-development activities. (1) Background: Unlike conventional vacancy-driven approaches, KCR is a proactive process through which firms deliberately access and import external organizational capabilities embodied in senior professionals—termed knowledge-hires—from rival organizations. These knowledge-hires embody tacit, socio-cognitive building blocks of capabilities developed through involvement in their prior employers’ routines and practices. (2) Methods: This article develops a micro-foundational model of KCR comprising four interrelated processes: external capability scanning and prioritization, identification of target capabilities and knowledge-hires, evaluation through the novel lens of contextual capability fit, and expectations of adaptation during onboarding. (3) Results: Contextual capability fit integrates complementary and supplementary quality with knowledge distance to enable firms to forecast both the strategic value of inbound capabilities and the hire’s expected socialization difficulty. (4) Conclusions: The primary theoretical contribution lies in advancing the learning-by-hiring literature by shifting the focus from passive knowledge diffusion to deliberate, calculative capability acquisition. By integrating insights from the knowledge-based view, person–organization fit, absorptive capacity, and strategic recruitment, the KCR model offers a coherent micro-foundational framework for transforming employee mobility into a source of sustained competitive advantage. Full article

The uniformity of local photoelectric properties in infrared detectors is critical for detection sensitivity. However, micro-nano-scale surface abnormalities introduced during mercury cadmium telluride (HgCdTe) fabrication systematically degrade in-plane photoelectric response consistency. To overcome the optical diffraction limits of standard far-field metrology, we utilized a cryogenic scattering-type scanning near-field optical microscopy (Cryo-SNOM) system to achieve the first super-resolution, in situ imaging of local near-field photocurrent in HgCdTe photoconductive detectors at 10 K. Device-level measurements reveal that sub-wavelength surface protrusions (~tens of nanometers high) act as strong recombination centers, suppressing local photocurrent and causing a consistent 10~20% relative signal attenuation compared to planar regions. Power and bias-dependent testing indicate these defects function as unsaturated linear recombination states. Increasing bias voltage amplifies the coupling between the external field and the defect’s built-in field, broadening the local depletion region and driving a non-linear escalation in the attenuation ratio. This study establishes quantitative engineering tolerances for morphological deviations at the nanoscale, providing critical criteria for the chip integration, structural optimization, and precision manufacturing of high-performance infrared sensing arrays. Full article

The effects of Ti/Nb microalloying-induced MC-type carbide precipitation and tempered microstructure evolution on the dry-sliding wear behavior of low-carbon martensitic wear-resistant steels were systematically investigated. Three experimental steels with different microalloying strategies (0.04Ti, 0.1Ti, and 0.04Ti/Nb) were subjected to quenching and subsequent tempering. Microstructural features, carbide characteristics, and mechanical properties were characterized using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), tensile testing, and impact testing, while wear performance was evaluated by pin-on-disk tests under dry-sliding conditions. The results indicate that wear resistance is governed by the combined effects of tempered martensite stability and MC-type carbide precipitation. Low-temperature tempering effectively reduces the wear mass loss of Ti-containing steels by enhancing their resistance to abrasive shear deformation while maintaining sufficient toughness. In contrast, the Nb-containing steel exhibits a stage-dependent wear response associated with the formation and destabilization of oxide-derived third-body debris during sliding. (Nb,Ti)C precipitates act as microscale load-bearing units, contributing to strength enhancement and subsurface damage suppression, but their influence on wear behavior strongly depends on tempering temperature. The dominant wear mechanism is abrasive micro-cutting, accompanied by fatigue-induced spalling and oxidation-assisted damage at later stages. These results demonstrate that wear performance cannot be correlated with hardness alone, but instead requires the coordinated optimization of carbide precipitation and tempered microstructural stability. This work provides microstructural guidance for the design of microalloyed martensitic wear-resistant steels. Full article

Modern scanning microscopes and robotic scanning systems increasingly use visual recognition and machine learning technologies to extract complex data from acquired images. This study examined sensor data fusion in optical imaging to detect and control the deviation of the position of the tool during various micro-manipulations for biologic and microscale engineering. The sensor data fusion study was performed using a scanning micro-robotic system with an integrated optical microscope and a vision sensor providing an image of the object’s bottom. The bottom vision sensor is a typical complementary metal–oxide–semiconductor sensor that is used to observe micrometer-sized semi-transparent objects. The challenge for sensor fusion in such a study is not only data fusion, but also the trajectory deviation inherent in directing the manipulator in the X and Y directions according to the selected trajectory. The data fusion method was applied to estimate deviations from the given trajectory of the scanning microscope. The unique novelty of this work is that an additional vision sensor is used to increase the accuracy of positioning determination of a scanning micro-robotic system, placed under the semi-transparent object, using the fusion of the obtained data, thus additionally controlling the objective deviations. By testing several known data fusion methods, a unique solution was achieved. The proposed sensor fusion method achieved a positioning accuracy of less than 0.5 μm at speeds up to 5 mm/s. Experimental results demonstrate that the system maintains high stability. This quantitative performance proves the system’s suitability for high-precision biological micro-manipulation, where mechanical drift was previously a limiting factor. Full article

This study evaluated the influence of scan rate (4.23 mm/s [S10] and 6.35 mm/s [S15]) on the localized corrosion and tribocorrosion behavior of a laser engineered net shaping (LENS)-produced stainless steel 316L (SS316L) in a phosphate-buffered saline (PBS) solution. Electrochemical impedance spectroscopy (EIS) was performed by applying an AC signal from 10⁵ to 10⁻² Hz and cyclic potentiodynamic polarization (CPP) was performed by sweeping from −150 mV to +1.5 V (vs. open circuit potential) and back to characterize passivation and pitting susceptibility. Potentiostatic tribocorrosion tests were conducted using a reciprocating tribometer integrated with a potentiostat to probe material response in passive and cathodic regimes. S15 exhibited manufacturing-related defects that served as preferential pit initiation sites, with pits in both S10 and S15 showing evidence of cell-interior dissolution. Electrochemical results indicated that the charge transfer resistance was reduced by 66% for S15 and that the repassivation potential decreased by 35% compared to S10. Under tribocorrosion, material degradation was dominated by mechanical wear for both samples. However, sliding significantly accelerated electrochemical dissolution in S15, with the corrosion rate affected by wear (V_c-w) increasing by 46.8%. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) of wear scars revealed plastic deformation, abrasive grooves, and bio-tribofilm formation composed primarily of phosphates. Micro-pits associated with processing defects were observed exclusively in S15. Overall, lower scan rate processing (S10) produced a more defect-resistant microstructure with improved resistance to localized corrosion and tribocorrosion in PBS. Full article

Nano-SiO₂-reinforced epoxy resin gel mortar (NERM) serves as an essential material for repairing and strengthening defective structures in civil engineering. This study developed a hybrid fiber-reinforced NERM (HF-NERM) by incorporating PVA–steel fiber, aiming to achieve superior mechanical properties, toughness, and bonding performance. This study systematically investigates the workability, mechanical properties, toughness, and bonding characteristics of HF-NERM, as well as their enhancement mechanisms characterized using scanning electron microscopy (SEM). Experimental results indicate that the slump of HF-NERM decreased significantly with increasing hybrid fiber content, and the regression coefficient of PVA fiber on slump was −86.7, while that of steel fiber was −4.5. The addition of hybrid fibers generally enhanced the mechanical properties. The optimal combination was 0.9% PVA fiber and 1.2% steel fiber, at which the flexural strength reached 11.56 MPa with an increase of 32.57%, splitting tensile strength reached 4.42 MPa with an increase of 20.1%, and interfacial bonding strength was improved by 9.8%. With the exception of splitting tensile strength, most mechanical properties initially increased and then decreased with increasing hybrid fiber content, indicating an optimal dosage. The hybrid fibers also enhanced the flexural toughness of HF-NERM; the toughness indices I₅, I₁₀ and I₂₀ were increased by 20.99%, 24.12% and 65.83%, respectively, and the residual strength factors R_5,10 and R_10,20 were increased by 26.8% and 160.8%. The hybrid fibers also enhanced the flexural toughness of HF-NERM. Mechanistically, PVA fibers primarily contributed to preventing the development of micro-cracks, while steel fibers were the main contributors to resisting macro-cracks. SEM observations demonstrated that the failure modes of PVA fibers involved synergistic mechanisms, while those of steel fibers were relatively singular. Related enhancement mechanisms were discussed based on the experimental results. Finally, the results demonstrate that NERM could be effectively strengthened by adding an appropriate content of hybrid fibers. This study’s novelty lies in quantifying the individual and synergistic effects of PVA–steel fibers in the NERM system, establishing optimal dosage parameters, and revealing matrix–fiber interaction mechanisms specific to epoxy-based composites. The findings provide a reliable material design basis for high-performance repair mortars and offer practical guidance for extending the service life of aging civil engineering structures. Full article

Inspired by the key hole concept in micro-surgery, we developed a “magnetic key hole concept” for basic studies of localized characteristics of soft magnetic laminations (electric steel, Fe-based amorphous ribbon) under exactly defined conditions of induction B(t). A material sample of 50 cm length and 10 cm width is magnetized in a novel multi-frequency SST that allows for exact sinus up to 10 kHz. A priori, the tester offers global results for permeability µ_G, power function p_G(t) and total loss P_G, as averaged over the entire sample material. But beyond that, a so-called Experimental Window (EW) offers additional information on local characteristics, as determined in a small central “key hole” region of defined magnetization. Here, a scanning adapter is mounted to study localized crystallographic features of the grain structure, as well as inhomogeneities, like failures, structure modifications, or specific technological treatment. Out of several types of sensor units a linear motor drive takes up a specific one within little manual effort. Already-developed sensor concepts concern the local tangential field, permeability, power, loss, and local widths of main domains and spike domains. The paper discusses several examples of analyses. Full article

This study aimed to assess how various remineralizing agents affect the demineralized enamel calcium/phosphorus ions (Ca/P) ratio and micro-tensile bond strength (μTBS) of orthodontic adhesive modified by Sepiolite nanoparticles (Sep-NPs). In addition, rheological properties and degree of conversion (DC) of the adhesive were investigated. One hundred and forty-four human premolars underwent a cariogenic challenge to induce artificial demineralization. Based on the remineralizing agents used, the samples were divided into four categories: silver diamine fluoride (SDF), rosmarinic acid (RMA), ROCS Medical Mineral Gel System (ROCS MMG), and control. The Ca/P ratio was evaluated using energy-dispersive X-rays. Thirty samples were divided into two subgroups: unmodified adhesive and 1% Sep-infiltrated adhesive. Brackets were bonded, and the μTBS was evaluated. Scanning electron microscopy was used to evaluate the resin–bracket interface. The modified and unmodified adhesives were subjected to DC and rheological testing. The Ca/P ion ratio was highest in the ROCS-MMG group and lowest in the no-remineralization group. Group 3B (ROCS MMG + SepNPs-Orthodontic adhesive) samples displayed the highest bond strength. The lowest μTBS was observed in Group 4A (no remineralization + orthodontic adhesive). ROCS MMG conferred the greatest improvement in µTBS and Ca/P ratio before bracket bonding, followed by SDF, whereas RMA did not enhance bonding outcomes. Sep-NP incorporation at 1% improved µTBS but compromised DC and rheological properties, necessitating concentration optimization before clinical application. Full article

Background: Finite element analysis (FEA) has become an important tool in restorative dentistry for investigating stress distribution in teeth and dental restorations. However, the accuracy of such analyses strongly depends on the anatomical fidelity of the underlying tooth models, which is often limited in simplified geometries. The objective of this study was to develop an anatomically accurate three-dimensional tooth model based on micro-computed tomography (micro-CT) data and to evaluate the biomechanical behaviour of sound and composite-restored teeth under clinically relevant loading conditions. Methods: A human tooth was scanned using high-resolution micro-CT imaging. Enamel, dentin, and pulp were segmented and reconstructed into three-dimensional geometries, which were further refined using computer-aided design (CAD) tools. The resulting models were imported into a finite element environment for mechanical simulation. Static loading conditions were applied to both sound and composite-restored tooth models, including a vertical load of 200 N and an oblique load of 200 N applied at a 45° angle to the tooth crown. Von Mises stress distributions were evaluated to characterize stress concentration patterns. Results: Finite element simulations revealed maximum von Mises stresses of approximately 140 MPa, predominantly localized in the coronal regions of the tooth. Oblique loading produced increased and more asymmetric stress concentrations than vertical loading, particularly in the anterior and posterior crown regions. While overall stress distributions were comparable between sound and composite-restored teeth, locally increased stress levels were observed in restored models under oblique loading. Conclusions: Anatomically accurate, micro-CT-based finite element tooth models provide a robust framework for biomechanical analysis in restorative dentistry. The presented workflow enables detailed evaluation of stress distribution in composite-restored teeth and may contribute to improved understanding and optimization of restorative materials and treatment strategies. Full article

Ageing radically alters the physicochemical properties of microplastics, significantly increasing their affinity for environmental pollutants. However, the slow nature of natural degradation necessitates the development of efficient laboratory protocols. This study establishes an accelerated ageing methodology that reflects natural dynamics by comparing Polyethene terephthalate microplastics (PET MPs) exposed to sunlight (3 months) with those exposed to laboratory UV-C radiation (varying lamp numbers and 24–336 h). scanning electron microscopy (SEM) imaging confirmed progressive surface degradation, including increased roughness, micro-cavities, and erosion. Photo-oxidation was evidenced by an increase in the carbonyl index (CI) from 7.43 ± 0.30 to 8.97 ± 0.35 (UV-aged) and 11.45 ± 0.45 (sun-aged). Furthermore, crystallinity significantly decreased from 59.5% to 54.4% and 16.6%, respectively, while the point of zero charge (pH_PZC) shifted from near neutral (6.5–7.0) to below 2.0. Notably, high-intensity, short-term UV-C exposure accelerated surface functionalization, enhancing cadmium adsorption capacity (q_e = 1.9 mg/g). The laboratory protocol provides rapid reactivation on the surface, serving as a proxy for prolonged sunlight exposure. Consequently, these findings offer a framework for assessing heavy metal uptake and the broader environmental implications of microplastics in aquatic environments. This understanding supports pollutant evaluation and sustainable water management for aquatic ecosystem protection. Full article

A compact millimeter-wave radar system operating at 33 GHz is presented for integration on small unmanned aerial systems (UAS) and for ground-based counter-UAS reconnaissance. The design is specifically motivated by civil-sector agricultural applications, where large-payload crop-dusting and precision-spraying drones operating under FAA 14 CFR Part 137 require lightweight sense-and-avoid radar that conforms aerodynamically to existing aircraft or ground vehicles. The system is based on a 36-element hemispherical conformal phased array of crossed half-wave dipole radiators that generate right-hand circular polarization (RHCP) on transmit and selectively receives left-hand circular polarization (LHCP) echoes from targets, providing passive first-stage suppression of co-polarized rain and ground clutter. A Linearly Constrained Minimum Variance (LCMV) digital beamformer, applied to per-element analog-to-digital converter (ADC) outputs, delivers closed-form beam weights that enforce a distortionless response at each scan direction while globally minimizing sidelobe power. The formulation resolves the main-beam drift caused by the ill-conditioned re-scaling step in iterative Chebyshev tapering, achieving sidelobe levels below $-20$ dB with main-beam peaks within $0.1$° of their commanded angles across all evaluated positions. Mutual coupling between array elements is modeled analytically using the induced-EMF method, yielding a $36\times 36$ impedance matrix whose off-diagonal entries are at most 8.2% of the element self-impedance at the minimum inter-element separation of 2.70 $\lambda$. A closed-form decoupling matrix is applied to the receive manifold prior to LCMV weight computation. Seven simultaneous independent receive beams covering $0$°–$60$° elevation are formed from a single data snapshot. A Scaled Conjugate Gradient neural network classifier, trained on radar-equation-scaled micro-Doppler features following Swerling I–IV radar cross-section (RCS) fluctuation statistics, achieves overall classification accuracy above 85% across five target classes. The five classes comprise two bird-signature classes (SW-I and SW-II), two UAV-signature classes (SW-III and SW-IV), and a clutter class. The design is entirely simulation-based; experimental validation using a sub-array prototype is identified as the primary direction for future work. Full article

Differential enrichment of shale oil hydrocarbon fractions exerts a fundamental control on the spatial distribution of “sweet spots” and the efficiency of unconventional resource recovery. This study investigates the continental shales of the Upper Es4 Member in the Dongying Sag, Bohai Bay Basin, through an integrated analytical framework combining Laser Scanning Confocal Microscopy (LSCM), Scanning Electron Microscopy (SEM), and high-pressure mercury intrusion. By moving beyond qualitative observations, we characterize the micro-scale partitioning of light and heavy fractions and establish a deterministic hierarchy of controlling factors. Our results indicate the following. (1) Mineral composition functions as a “primary geochemical filter,” where carbonate minerals exhibit a preferential adsorption affinity for light fractions (≤ C₁₈), while clay minerals facilitate the selective retention of heavy components (> C₁₈). (2) Pore–throat architecture acts as a “secondary mobility modulator.” A statistically significant linear correlation (R² = 0.72, p < 0.05) was identified between mean pore diameter and the light-to-heavy fluorescence ratio, suggesting that interconnected macropores in carbonate laminae provide low-resistance conduits for light oil accumulation, whereas isolated mesopores in argillaceous matrices promote heavy-component sequestration. (3) Thermal maturity (Ro) drives a progressive shift in the light-to-heavy ratio, enhancing oil fluidity and regulating the transition from adsorption-dominated to migration-dominated enrichment. This study clarifies the lithofacies-dependent coupling mechanisms between mineral diagenesis and pore-scale fractionation, providing a semi-quantitative conceptual model for shale oil sweet-spot prediction in complex lacustrine basins. Full article

The ambient stability of ambient-processed lead-free perovskite absorbers remains a critical challenge toward scalable, eco-friendly photovoltaics. Herein, we systematically investigate the time-dependent structural and morphological evolution of drop-cast ambient-processed Cs₃Sb₂I₉ thin films, being a potential non-toxic and stable solar absorber candidate (energy bandgap ~2 eV) for solar cells, stored under uncontrolled ambient condition (~60% Relative humidity) for 28 days. Sequential X-ray diffraction (XRD) and surface morphology analyses using scanning electron microscope (SEM) reveal that the films preserve their trigonal P$\overline{3}$m1 phase throughout aging, confirming phase stability. Moderate moisture exposure may induce partial recrystallization and subtle structural reorganization, possibly including minor c-axis realignment, leading to reduced lattice strain and improved crystallite coherence. Even after prolonged aging, no secondary phases or micro-cracks are detected, underscoring the slow degradation kinetics and robust Sb–I bonding that stabilize the layered [Sb₂I₉]³⁻ dimers. The late-stage increase in diffraction intensity and partial recovery of crystallographic parameters could indicate transient structural reorganization, potentially associated with moisture-mediated reordering within an overall degradation pathway. These observations suggest some degree of morphological persistence and structural tolerance of Cs₃Sb₂I₉ under ambient conditions, rather than complete stability. This behavior offers useful insights into ambient processing and the long-term reliability of lead-free perovskite photovoltaics. Full article

Broadband antireflective surface technology constitutes a crucial technique in optoelectronic devices, playing a key role in reducing optical losses. Ultrafast laser processing provides a flexible route for fabricating micro-nano structures on metallic surfaces because it enables efficient fabrication, high spatial resolution, and minimal chemical consumption. This study uses a variable-angle scanning strategy to texture the copper surface, produce a series of antireflection arrayed micro-nano structures, and study the spectral reflectance characteristics of the copper surface. The results exhibit that 90° orthogonal scanning favors the formation of an arrayed microcone structure, which shows lower reflectance than the non-orthogonal scanning strategies in the 200–1300 nm band, with a minimum reflectance of 0.94%. The 60° and 45° cross-scanning based on the non-orthogonal strategy favors the formation of microcavity structures, and shows low reflectance in the 1300–2500 nm band, with the maximum reflectance remaining below 5%. Laser-induced periodic surface structures (LIPSS) are observed on the structures fabricated by all strategies. This work demonstrates that the scanning angle itself can be used to switch the dominant surface morphology and thereby tailor the spectral antireflection response, and lies in establishing a clear processing–structure–spectral response relationship for copper surfaces, which provides a designable route for wavelength-selective optical absorption in photothermal conversion, infrared detection, and sensing applications. Full article

A non-contact laser polishing method for additively manufactured polymer components with complex three-dimensional geometries is presented, employing a 6-axis robotic system. Robot-guided sample orientation, a quasi-top-hat scanning strategy, and closed-loop temperature control are combined to address curved geometries. On Selective Laser Sintering (SLS)-manufactured Polyamide 12 (PA12) tensile samples with three build orientations and two thicknesses, laser polishing yields up to a 15% increase in tensile strength (Rm) and a 50% increase in elongation at break (A). For 45°-built 5 mm samples, Rm increases from 31.53 MPa to 36.33 MPa and A from 6.52% to 9.8%, approaching the tensile strength reported for optimally oriented SLS-printed PA12 Smooth samples of the same grade. For convex–concave PA12 demonstrators, areal roughness (Sa) on convex surfaces is reduced from 33.6 µm to 2.7 µm (approximately 92%) and the high-pass-filtered micro-roughness (Sa_HP) on concave surfaces by 98.2% to 0.15 µm. For Fused Deposition Modeling (FDM)-printed Polyaryletherketone (PAEK) samples, Sa is reduced from 28.35 µm to 4.1 µm and Sa_HP from 15.98 µm to 0.23 µm (98.6%), despite the high melting temperature and anisotropic raster topography. These results demonstrate that robotic laser polishing constitutes a viable post-processing approach for functionally demanding polymer applications. Full article