Bright-field Optical Microscopy Research Articles

Single-Cell Sensitive Colorimetric pH Detection Based on Microscope Ratiometric Grayscale.

Rapid and accurate identification of the intracellular pH is critical in the field of biomedicine. In this work, we effectively identified and quantified the intracellular pH and its distribution at the single-cell level using an image sensor based on an ordinary bright-field optical microscope that divided the cell staining images into their red (R) and blue (B) channels. The grayscale of the R and B channels was subjected to a ratiometric operation to generate ratiometric grayscale cell images of the microscope. A standard curve of pH against ratiometric grayscale curve was then obtained by incubating HeLa cells at pH 6.00-7.60 in a high concentration K+ ion buffer solution containing nigericin for obtaining certain intracellular pH values. A good correlation was evidenced between pH and the ratiometric grayscale of the R and B channels in the pH range of 6.00-7.60. Subsequently, the intracellular pH value of the A549 cells under the experimental conditions was measured to be 7.22 ± 0.01 by the method. Furthermore, the changes in the intracellular pH of HeLa cells stimulated with hydrogen peroxide were sensitively monitored, which demonstrated the applicability of the method. Due to its ease of use, the developed colorimetric microscopy pH detection and monitoring method provide prospects for pH-related single-cell studies.

Magnetic Separation of Micro Beads and Cells on a Paper-Based Lateral Flow System

Paper based lateral flow systems are widely used biosensor platforms to detect biomolecules in a liquid sample. Proteins, bacteria, oligonucleotides, and nanoparticles were investigated in the literature. In this work we designed a magnetic platform including dual magnets and tested the flow of micron size immunomagnetic particles alone and when loaded with cells on two different types of papers. The prewetting conditions of the paper and the applied external magnetic field are the two dominant factors affecting the particle and cell transport in paper. The images recorded with a cell phone, or with a bright field optical microscope were analyzed to measure the flow of particles and cells. The effect of prewetting conditions and magnetic force were measured, and it was shown that in the worst case, minimum 90% of the introduced cells reached to the edge of the paper. The paper based magnetophoretic lateral flow systems can be used for cell assays.

Phase behavior of gas condensate in fractured-vuggy porous media based on microfluidic technology and real-time computed tomography scanning

With the development of gas-condensate reservoirs, the phase behavior of gas condensate undergoes continuous changes. The phase behavior of gas condensate in PVT cylinders is different from that in fractured-vuggy gas-condensate reservoirs because multiscale pore structures can affect the phase behavior. By vuggy, we mean the formation of a reservoir contains cavity structures. To elucidate the influence of fractured-vuggy porous media on phase behavior of gas condensate, a microfluidic chip and a fractured-vuggy carbonate sample were prepared for pressure depletion experiments. The phase behavior of gas condensate in the chip during depressurization was observed via brightfield optical microscopy. The real-time computed tomography scanning was used to analyze pore structure of the sample and to obtain the phase behavior of gas condensate under different pressures. The results showed that the dew point pressure of the gas condensate was increased from 12.0 MPa in PVT cylinders to 14.8 MPa in nanochannels of the chip. The condensate liquid appeared in micropores at 14.4 MPa. The change of the average radius, coordination number, and tortuosity of condensate liquid ganglia were calculated and analyzed using pore network models. The shape factor and the Euler number were used to classify the condensate liquid into four types including clustered, branched, membranous, and droplets ganglia. The condensate liquid was generally distributed as clustered ganglia. This study provided evidence of the effect of fractured-vuggy porous media on phase behavior of gas condensate and clarified that the phase behavior of gas condensate varies in multi-scale pores.

Hydrogen Diffusion in Nickel Superalloys: Electrochemical Permeation Study and Computational AI Predictive Modeling.

Ni-based superalloys are materials utilized in high-performance services that demand excellent corrosion resistance and mechanical properties. Its usages can include fuel storage, gas turbines, petrochemistry, and nuclear reactor components, among others. On the other hand, hydrogen (H), in contact with metallic materials, can cause a phenomenon known as hydrogen embrittlement (HE), and its study related to the superalloys is fundamental. This is related to the analysis of the solubility, diffusivity, and permeability of H and its interaction with the bulk, second-phase particles, grain boundaries, precipitates, and dislocation networks. The aim of this work was mainly to study the effect of chromium (Cr) content on H diffusivity in Ni-based superalloys; additionally, the development of predictive models using artificial intelligence. For this purpose, the permeability test was employed based on the double cell experiment proposed by Devanathan-Stachurski, obtaining the effective diffusion coefficient (Deff), steady-state flux (Jss), and the trap density (NT) for the commercial and experimentally designed and manufactured Ni-based superalloys. The material was characterized with energy-dispersed X-ray spectroscopy (EDS), atomic absorption, CHNS/O chemical analysis, X-ray diffraction (XRD), brightfield optical microscopy (OM), and scanning electron microscopy (SEM). On the other hand, predictive models were developed employing artificial neural networks (ANNs) using experimental results as a database. Furthermore, the relative importance of the main parameters related to the H diffusion was calculated. The Deff, Jss, and NT achieved showed relatively higher values considering those reported for Ni alloys and were found in the following orders of magnitude: [1 × 10-8, 1 × 10-11 m2/s], [1 × 10-5, 9 × 10-7 mol/cm2s], and [7 × 1025 traps/m3], respectively. Regarding the predictive models, linear correlation coefficients of 0.96 and 0.80 were reached, corresponding to the Deff and Jss. Due to the results obtained, it was suitable to dismiss the effect of Cr in solid solution on the H diffusion. Finally, the predictive models developed can be considered for the estimation of Deff and Jss as functions of the characterized features.

A-135 Improving Cell Count Turnaround Times With the GloCyte® Automated Cell Counter for CSF: A Retrospective Study at MercyOne Des Moines Medical Center

Abstract Background Accurate, STAT cerebrospinal fluid (CSF) cell counts are critical in the diagnosis of meningitis, malignancy, demyelinating disease, and hemorrhage. Due to historical limitations with the linearity of automated analyzers, CSF cell counts have traditionally been performed manually with a hemocytometer and the aid of a brightfield optical microscope. Manual cell counting is time-consuming, subjective due to reliance on human interpretation, and requires a high degree of skill. This poses significant challenges for clinical laboratories of all sizes facing unprecedented med tech shortages. The purpose of this study was to evaluate the impact of implementing the GloCyte Automated Cell Counter for CSF, an FDA-cleared device with linearity down to 0 cells/µL, on result turnaround times. Methods Result turnaround time data for CSF specimens processed in the hematology lab at MercyOne Des Moines Medical Center, a 600-bed hospital in Des Moines, Iowa, was analyzed in a retrospective study of two cell counting methods- (1) manual cell counting using a Neubauer-Improved hemocytometer and (2) GloCyte, a benchtop cell counting device that uses fluorescence technology and highly specific reagents to automate RBC and TNC cell counts in less than 5 min. Turnaround times for 227 CSF specimens counted manually during an approximately six-month period prior to the implementation of GloCyte (January 2, 2017 to June 29, 2017) were compared to those for 133 specimens analyzed on GloCyte over a similar duration (January 4, 2021 to June 30, 2021). In this study, turnaround times were defined as the time between specimen arrival in the lab and result verification. Correlation between the methods was previously established in the MercyOne Des Moines Medical Center laboratory. Results The data demonstrated a significant, 16–30-minute improvement in turnaround times with GloCyte compared to the manual hemocytometer method. Median turnaround times, analyzed to adjust for add-ons that resulted in longer turnaround times pre- and post-GloCyte implementation, were 1:38h for specimens counted manually vs 1:08 h for specimens analyzed on GloCyte. The average turnaround time for the 227 CSF specimens counted manually was 2:03 h compared to 1:46 h for the 133 samples analyzed on GloCyte. The MercyOne Des Moines Medical Center laboratory processed 456 CSF cell counts in 2022, equating to a reduction in turnaround time of 122–228 h annually with the implementation of GloCyte. Conclusion This study demonstrates that GloCyte can be implemented to significantly improve turnaround times for CSF cell counts. The MercyOne Des Moines Medical Center laboratory realized several benefits from the reduction in turnaround times- GloCyte has (1) freed up significant tech time for other tasks, (2) standardized CSF cell counting to mitigate tech to tech variability, (3) increased lab staff satisfaction and decreased stress levels, and (3) increased physician satisfaction. For MercyOne Des Moines Medical Center’s sister site, MercyOne West Des Moines Medical Center, a 146-bed hospital that infrequently performs CSF cell counts, GloCyte has provided peace of mind in performing cell counts accurately with techs of all skill levels.

Experimental stability investigation of different water-in-jojoba biodiesel emulsions

Investigating the stability of water in biodiesel emulsion fuels during storage and engine operation is crucial to consider for marketing processes. This study examines the stability of water-in-Jojoba biodiesel (WJBD) emulsion that is stabilized using three commercially available surfactants, Span-80 (HLB 4.3), Tween-80 (HLB 15), Triton X-100 (HLB 13.5). The investigation involves varying the composition of the emulsions by adjusting factors such as the hydrophile lipophile balance (HLB), surfactant concentration, water concentration, mixing speed, and mixing duration, and study their effects through a bottle test. Stable emulsions are studied by bright field optical microscopy, constant shear test, and thermal loop rheology test. The research reveals that Tween-80 (HLB 15) and Span-80 (HLB 4.3) effectively yield emulsions with high relative stability. Specifically, at 5 (v%) water concentration, emulsions prepared with Tween-80 (HLB 15) demonstrate the formation of water droplets as small as 3.88 µm. Additionally, emulsions at various water concentrations are thoroughly studied. Over time, phase separation is studied by microscopic images and showed minimal coalescence after the first day for the emulsions that showed promising stability in the bottle test. To further assess the stability, the stable emulsions undergo continuous shear test, wherein a consistent pattern of stable viscosity is observed as time passed. Moreover, the thermal loop test showed minimal change in the relative microstructure of the emulsion, where the difference in the storage modulus and the loss modulus didn’t exceed 15 % and 5 %, respectively. Understanding the change in microstructure, droplet sizes, and how the emulsions behave under certain shear stresses is critical for practical applications of this fuel. Through comprehending the factors that influence the emulsion stability, this study contributes valuable insights for the successful storage and engine operation of the WJBD.

Surfactant-Mediated Structural Modulations to Planar, Amphiphilic Multilamellar Stacks.

The hydrophobic effect, a ubiquitous process in biology, is a primary thermodynamic driver of amphiphilic self-assembly. It leads to the formation of unique morphologies including two highly important classes of lamellar and micellar mesophases. The interactions between these two types of structures and their involved components have garnered significant interest because of their importance in key biochemical technologies related to the isolation, purification, and reconstitution of membrane proteins. This work investigates the structural organization of mixtures of the lamellar-forming phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and two zwitterionic micelle-forming surfactants, being n-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (Zwittergent 3-12 or DDAPS) and 1-oleoyl-2-hydroxy-sn-glycero-3-phosphocholine (O-Lyso-PC), when assembled by water vapor hydration with X-ray diffraction measurements, brightfield optical microscopy, wide-field fluorescence microscopy, and atomic force microscopy. The results reveal that multilamellar mesophases of these mixtures can be assembled across a wide range of POPC to surfactant (POPC:surfactant) concentration ratios, including ratios far surpassing the classical detergent-saturation limit of POPC bilayers without significant morphological disruptions to the lamellar motif. The mixed mesophases generally decreased in lamellar spacing (D) and headgroup-to-headgroup distance (Dhh) with a higher concentration of the doped surfactant, but trends in water layer thickness (Dw) between each bilayer in the stack are highly variable. Further structural characteristics including mesophase topography, bilayer thickness, and lamellar rupture force were revealed by atomic force microscopy (AFM), exhibiting homogeneous multilamellar stacks with no significant physical differences with changes in the surfactant concentration within the mesophases. Taken together, the outcomes present the assembly of unanticipated and highly unique mixed mesophases with varied structural trends from the involved surfactant and lipidic components. Modulations in their structural properties can be attributed to the surfactant's chemical specificity in relation to POPC, such as the headgroup hydration and the hydrophobic chain tail mismatch. Taken together, our results illustrate how specific chemical complexities of surfactant-lipid interactions can alter the morphologies of mixed mesophases and thereby alter the kinetic pathways by which surfactants dissolve lipid mesophases in bulk aqueous solutions.

Effect of a Change in the CaCl2/Pectin Mass Ratio on the Particle Size, Rheology and Physical Stability of Lemon Essential Oil/W Emulgels

A three-step (rotor-stator-microfluidization-rotor stator) protocol was used to prepare 15% lemon essential oil in water emulgels using a mixture of Tween 80 and Span 20 surfactants as low molecular mass emulsifiers and 0.4% low-methoxyl citrus peel pectin as a gelling agent. Ca2+ was used as a gel-promoting agent. Different CaCl2/pectin mass ratio values from 0.3 to 0.7 were used. Emulgels showed a microstructure consisting of oil droplets embedded in a sheared gel matrix, as demonstrated by bright field optical microscopy. Laser diffraction tests showed multimodal particle size distributions due to the coexistence of oil droplets and gel-like particles. Multiple light scattering tests revealed that the physical stability of emulgels was longer as the CaCl2/pectin mass ratio decreased and that different destabilization mechanisms took place. Thus, incipient syneresis became more important with increasing CaCl2 concentration, but a parallel creaming mechanism was detected for CaCl2/pectin mass ratio values above 0.5. Dynamic viscoelastic and steady shear flow properties of the emulgels with the lowest and highest CaCl2/pectin mass ratio values were compared as a function of aging time. The lowest ratio yielded an emulgel with enhanced connectivity among fluid units as indicated by its wider linear viscoelastic region, higher storage modulus, loss modulus and viscosity values, and more shear thinning properties than those of the emulgel formulated with the highest CaCl2/pectin mass ratio. The evolution of the dynamic viscoelastic properties with aging time was consistent with the information provided by monitoring scans of backscattering as a function of sample height.

Destabilization of Pickering emulsions by interfacial transport of mutually soluble solute

HypothesisPickering emulsions (PEs) once formed are highly stable because of very high desorption energies (∼107 kBT) associated with particles adsorbed to the interfaces. The destabilization of PEs is required in many instances for recovery of valuable chemicals, products and active compounds. We propose to exploit interfacial instabilities develop by the addition of different types of solutes to PEs as a route to engineer their destabilization. ExperimentsPEs stabilized by (i) spherical particles, (ii) non-spherical particles, (iii) oppositely charged particle–particle mixtures, and (iv) oppositely charged particle-polyelectrolyte mixtures are formulated. Different types of solutes are added to these highly stable PEs and the macroscopic as well as microscopic changes induced in the PEs is recorded by visual observation and bright field optical microscopy. FindingsOur results point to a simple yet robust method to induce destabilization of PEs by transiently perturbing the oil–water interface by transport of a mutually soluble solute across the interface. The generality of the method is demonstrated for different kind of solutes and stabilizers including particles of different sizes (nm to µm), shapes (sphere, spheroids, spherocylinders) and types (polystyrene, metal oxides). The method works for both oil-in-water (o/w) and water-in-oil (w/o) PEs with different kinds of non-polar solvents as oil-phase. However, the method fails when the solute is insoluble in one of the phases of PEs. The study opens up a new approach to destabilization of particle stabilized emulsions.

Simple Staining of Cells on a Chip.

Simple staining of cells is a widely used method in basic medical diagnostics, education, and research laboratories. The stains are low-cost, but the extensive consumption results in excessive toxic waste generation. Thus, to decrease the amount of toxic waste resulting from the cell staining procedure is a need. In this study, we developed a magnetically driven and compartmentalized passive microfluidic chip to perform simple staining of human eukaryotic cells, K562 cells, and lymphocyte cells derived from patients. We demonstrated simple staining on cells with trypan blue, methylene blue, crystal violet, and safranin for high, medium, and low cell densities. The stained cells were imaged using a bright field optical microscope and a cell phone to count cells on the focal plane. The staining improved the color signal of the cell by 25-135-pixel intensity changes for the microscopic images. The validity of the protocol was determined using Jurkat and MDA-MB-231 cell lines as negative controls. In order to demonstrate the practicality of the system, lymphocyte cells derived from human blood samples were stained with trypan blue. The color intensity changes in the first and last compartments were analyzed to evaluate the performance of the chip. The developed method is ultra-low cost, significantly reduces the waste generated, and can be integrated with mobile imaging devices in terms of portability. By combining microfabrication technology with cell staining, this study reported a novel contribution to the field of microfluidic biosensors. In the future, we expect to demonstrate the detection of pathogens using this method.

Microplastic-Free Microcapsules to Encapsulate Health-Promoting Limonene Oil.

Fast-moving consumer goods (FMCG) industry has long included many appealing essential oils in products to meet consumers' needs. Among all, the demand for limonene (LM) has recently surged due to its broad-spectrum health benefits, with applications in cosmetic, detergent, and food products. However, LM is extremely volatile, hence has often been encapsulated for a longer shelf-life. To date, mostly non-biodegradable synthetic polymers have been exploited to fabricate the microcapsule shells, and the resulting microcapsules contribute to the accumulation of microplastic in the environment. So far, information on LM-entrapping microcapsules with a natural microplastic-free shell and their mechanism of formation is limited, and there is lack of an in-depth characterisation of their mechanical and adhesive properties, which are crucial for understanding their potential performance at end-use applications. The present research aims towards developing safe microcapsules with a core of LM fabricated via complex coacervation (CC) using gum Arabic (GA) and fungally sourced chitosan (fCh) as shell precursors. The encapsulation efficiency (EE) for LM was quantified by gas chromatography (GC) separation method. The morphology of microcapsules was investigated via bright-field optical microscopy and scanning electron microscopy, and their mechanical properties were characterised using a micromanipulation technique. Moreover, the adhesive properties of the resulting microcapsules were studied via a bespoke microfluidic device fitted with a polyethylene-terephthalate (PET) substrate and operating at increasingly hydrodynamic shear stress (HSS). Spherical core-shell microcapsules (EE ~45%) with a mean size of 38 ± 2 μm and a relatively smooth surface were obtained. Their mean rupture force and nominal rupture stress were 0.9 ± 0.1 mN and 2.1 ± 0.2 MPa, respectively, which are comparable to those of other microcapsules with synthetic shells, e.g., urea- and melamine-formaldehyde. It was also found that the fCh-GA complexed shell provided promising adhesive properties onto PET films, leading to a microcapsule retention of ~85% and ~60% at low (≤50 mPa) and high shear stress (0.9 Pa), respectively. Interestingly, these values are similar to the adhesion data available in literature for microplastic-based microcapsules, such as melamine-formaldehyde (50-90%). Overall, these findings suggest that microplastics-free microcapsules with a core of oil have been successfully fabricated, and can offer a potential for more sustainable, consumer- and environmentally friendly applications in FMCGs.

Picosecond infrared laser driven sample delivery for simultaneous liquid-phase and gas-phase electron diffraction studies.

Here, we report on a new approach based on laser driven molecular beams that provides simultaneously nanoscale liquid droplets and gas-phase sample delivery for femtosecond electron diffraction studies. The method relies on Picosecond InfraRed Laser (PIRL) excitation of vibrational modes to strongly drive phase transitions under energy confinement by a mechanism referred to as Desorption by Impulsive Vibrational Excitation (DIVE). This approach is demonstrated using glycerol as the medium with selective excitation of the OH stretch region for energy deposition. The resulting plume was imaged with both an ultrafast electron gun and a pulsed bright-field optical microscope to characterize the sample source simultaneously under the same conditions with time synchronization equivalent to sub-micrometer spatial resolution in imaging the plume dynamics. The ablation front gives the expected isolated gas phase, whereas the trailing edge of the plume is found to consist of nanoscale liquid droplets to thin films depending on the excitation conditions. Thus, it is possible by adjusting the timing to go continuously from probing gas phase to solution phase dynamics in a single experiment with 100% hit rates and very low sample consumption (<100 nl per diffraction image). This approach will be particularly interesting for biomolecules that are susceptible to denaturation in turbulent flow, whereas PIRL–DIVE has been shown to inject molecules as large as proteins into the gas phase fully intact. This method opens the door as a general approach to atomically resolving solution phase chemistry as well as conformational dynamics of large molecular systems and allow separation of the solvent coordinate on the dynamics of interest.

Comparison of microscopic techniques to study the diversity of the bitumen microstructure

Bitumen characterisation and differentiation usually involve a combination of mechanical and chemical analyses. However, these methods provide limited information on the diversity caused by the binders’ origin or processing method. Thus, the question arises whether the bitumen microstructure can be used to identify these issues. In this study, microscopic methods, including brightfield, darkfield and fluorescence optical inverse microscopy (OIM), as well as confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM), were used to investigate the bitumen surface. Five different binders varying in their origin and production method were selected. The results show that CLSM, AFM and OIM darkfield can adequately capture a specific surface microstructure known as the bee structure, whereas brightfield in the OIM and optical CLSM show the surrounding peri phase, which exhibits a strong fluorescence. All visbroken binders show bee structures surrounded by a pronounced peri phase. On the other hand, one of the straight distilled binders does not show any microstructure, while the second straight distilled binder displays smaller bee structures surrounded by a small peri phase. Results from the image processing evaluation reveal that the area covered by bee structures is in the range of 2.4 – 4.3% for those binders that developed a surface microstructure. These results indicate a good accordance between the three microscopic techniques selected. However, a clear differentiation between the binders is difficult to obtain. Nonetheless, this work shows how these techniques can be used to their maximum capabilities regarding the obtained microstructural information and may help solve future questions regarding ageing, modification or rejuvenation.

A laser-based phase plate for cryo-electron microscopy

Transmission electron microscopy of vitrified biological macromolecules and cells (cryo-EM), which is becoming a preferred method in the area of high-resolution structural biology, is limited by low signal-to-noise ratio. This is because the samples only weakly modulate the phase, and not the amplitude of the transmitted electron beam. In addition, defocusing the images provides an incomplete conversion of this phase modulation to detectable intensity modulation. Phase plates have long been used to address a similar problem that exists in bright-field optical microscopy of unstained samples, but such devices have been difficult to realize in electron microscopy without causing unwanted wave-front aberrations or resolution loss due to charging or scattering.

Vibrational imaging for label-free cancer diagnosis and classification

The first key step in the detection and classification of most cancers is the microscopic assessment of thin tissue slices, the so-called “histopathology”. This procedure is still nowadays, similarly to 150 years ago, performed by staining the tissue with two or more dyes able to bind to specific biological structures, followed by visual inspection by the histopathologist under the bright-field optical microscope. This approach involves long manual procedures which can be accompanied by human errors, subjectivity, and lack of reproducibility. Vibrational microscopies are capable of directly providing chemical and biomolecular information on tissues, identifying them through their fingerprint vibrational spectra without the need of staining and, thus, constitute powerful tools for label-free and objective tumour identification. The two most established techniques, spontaneous Raman microscopy and infrared absorption microscopy, suffer, respectively, from long acquisition times and low spatial resolution. These limitations can be overcome by novel and more technically demanding approaches such coherent Raman scattering and photothermal infrared microscopy. Here we present an extended overview of the major advances in the field of vibrational imaging for cancer diagnosis. We start from a detailed description of the different technologies and then present examples of their applications to tissue imaging for cancer assessment. We critically compare the presented approaches, discussing the steps required to bring these powerful technologies from bench to bedside.

Binding of lambda carrageenan to bovine serum albumin and non-equilibrium effects of complexation

Binding of lambda carrageenan (lCG) to bovine serum albumin (BSA) and the effect of the formation path, namely mixing (M) at specific pH versus titration (T) from a neutral mixture, on complexation have been studied using turbidimetry, phase analysis, dynamic light scattering, confocal laser scanning and bright-field optical microscopy, circular dichroism and fluorescence measurements. The sizes and shape of the complex particles formed under T-conditions differ significantly from those obtained under M-conditions, and at maximal complexation T-complexes contain significantly less lCG as compared to M-complexes. At a pH below pIBSA phase analysis reveals two domains of q corresponding to an approximately constant lCG/BSA weight ratio in the complex phase q* (domain I), and a decreasing q* (domain II). Binding stoichiometries at pH 4.2 and 4.7 are 1:77 and 1:119 mole lCG/mole BSA. The yield of BSA in the complex phase is higher than 98% at pH 4.2 and 4.7, and the complexes form and are stable in the presence of 1.0M–1.5M NaCl. The interaction did not lead to protein denaturation or significant changes in the tertiary and secondary structure and illustrates an enhancement of the hydrophobicity of the protein within the complex particles. At pH 5.2 (pH on the wrong side of PIBSA) up to 37.6% BSA was bound to lCG, and the weight ratio of lCG/BSA in the complex particles (q*) was weakly dependent on q in the complete q range studied. The molecular origin of the unusually strong interaction between lCG and BSA is discussed.

Morphological Characteristics of the Sperm of the Peregrine Falcon (Falco peregrinus) during the Reproductive Season.

The morphological characteristics of different sperm cells (normal, abnormal, and immature) in the peregrine falcon during the reproductive season were analysed. We also classified the main sperm defects found in semen. Semen samples were collected from mature peregrine falcons via cloacal massage and stained with Diff-Quik stain. The percentages of normal, abnormal, and immature sperm cells were determined by bright-field optical microscopy. The number of normal spermatozoa were greater at the initial stage and subsequently decreased during the middle and later stages of the reproductive season (p < 0.01). In contrast, the percentage of abnormal spermatozoa increased significantly in the middle and end stages of the reproductive season (p < 0.05), whereas the proportion of immature spermatozoa remained stable during the study. Head defects represented the greatest proportion of morphological abnormalities, followed by the defects in the tail and midpiece regions. A small percentage of multiple defects and cytoplasmic droplets were also observed in the falcon spermatozoa. The findings of this study might be important for the development of future conservation protocols for falcon sperm.

An Optically Reconfigurable Förster Resonance Energy Transfer Process for Broadband Switchable Organic Single-Mode Microlasers

An Optically Reconfigurable Förster Resonance Energy Transfer Process for Broadband Switchable Organic Single-Mode Microlasers

Flaw Identification in Additively Manufactured Parts Using X-ray Computed Tomography and Destructive Serial Sectioning

In additive manufacturing (AM), internal flaws that form during processing can have a detrimental impact on the resulting fatigue behavior of the component. Nondestructive x-ray computed tomography (XCT) has been routinely used to inspect AM components. This technique, however, is limited by what is resolvable as well as the automated procedures available to analyze the data. In this study, we compared XCT scans and automated flaw recognition analysis of the corresponding data to results obtained from an automated mechanical polishing-based serial sectioning system. Although internal porosity and surface roughness were easily observed by serial sectioning with bright-field optical microscopy, the same level of information could not be obtained from the XCT data. For the acquisition parameters used, XCT had only a 15.7% detection rate compared to that of serial sectioning. The results point to the need to recognize the limitations of XCT and for supplementary XCT scan quality metrics in addition to the voxel size.

Temperature-dependent Pattern Formation in Drying Aqueous Droplets of Lysozyme

Drying colloidal droplets have a wide range of applications from medical diagnostics to coatings for industries. This paper explores the effects of the substrate temperature (ranging from $25$ to $55 ^{\circ}$C) and various initial concentrations ($\phi$) of $1$ to $20$ wt% of lysozyme in an aqueous solution on its drying and final dried film state using bright-field optical microscopy. The $\phi$ is divided into three regimes, ultra-concentrated ($20$ $<$ $\phi$ $\leq$ $17$ wt%), concentrated ($17$ $<$ $\phi$ $\leq$ $9$ wt%) and diluted ($9$ $<$ $\phi$ $\leq$ $1$ wt%). Increasing $\phi$ in these regimes finds that this movement in the later non-linear region slows down as the front carries and deposits protein molecules until the supply in solution is exhausted. In the ultra-concentrated regime, the fluid front moves linearly throughout the drying process. The deposition of protein onto the surface by the fluid front creates the coffee-ring and increases with increasing $\phi$. A dimple is observed in a central mound-structure, which grows with increasing $\phi$. As the temperature increases the drying rate increases, reducing the time for convective flow and the deposition of material at the fluid front. Interestingly, at (T, $\phi$) = ($55 ^{\circ}$C, $20$ wt%), the droplet forms the thickest film with suppressed ring formation. The dimple diminishes in the ultra-concentrated regime, whereas it changes to an expanded spot in some samples of the diluted and concentrated regimes with elevated temperatures. Both initial concentration and substrate temperature lead to surface tension and temperature gradients across the droplet, affecting the morphological patterns. This study provides insights into protein-protein and protein-substrate interactions driven by temperature and concentration for biomedical and biosensing applications.