Tip Aperture Research Articles

Optimizing Infusate Flow Patterns for Minimizing Vein Wall Trauma: An Exploratory Study with a Modified off-Axis Catheter Tip Opening.

Modifying the PIVC tip to direct infusates toward areas of highest hemodilution may reduce vein wall damage. This study compared flow patterns between a traditional PIVC with a central opening and one with an off-axis aperture. This was an exploratory observational analysis conducted at a tertiary care emergency department (ED) comparing flow patterns of two intravenous catheters: PIVC 1 (2.95 cm 20 gauge [Autoguard, Becton Dickinson]) and PIVC 2 (3.68 cm 20 gauge [Osprey, SkyDance Vascular]). Adult ED patients with PIVCs placed via traditional palpation/visualization method and with ultrasound capturing the flushing were eligible participants. Ultrasounds were reviewed to determine vein, catheter, and flow characteristics. The primary outcome was angle of the infusate leaving the catheter. Secondary outcomes included direction of catheter tip against vein wall, distance away from vein wall, vasospasm, and laminar/turbulent flow. Data from December 2023 included 28 catheters (10 PIVC 1, 18 PIVC 2). The average patient age was 53.7 years; 53.6% were female. Vein diameter/depth were similar: 0.35 cm/0.41 cm for PIVC 1 and 0.37 cm/0.47 cm for PIVC 2. The catheter tip pointed posteriorly towards the vein wall in 60% of PIVC 1 vs 11.1% in PIVC 2 (P=0.018). The angle of infusate flow away from the vein wall was 0.20° (SD 0.63) for PIVC 1 and 7.61° (SD 5.71) for PIVC 2 (P<0.001). Flow at 0° occurred in 90% of PIVC 1 vs 16.7% in PIVC 2 (P<0.001). In this exploratory investigation, a peripheral vascular access device with an off-axis tip aperture of demonstrated a sharper infusate flow angle away from the vein wall compared to a traditional central opening device. This redirection may reduce vein wall trauma and complications, though further research is needed to pair clinical outcomes with this technology.

Selective Initiation of Corrosion Pits in Stainless Steel Using Scanning Electrochemical Cell Microscopy.

Scanning electrochemical cell microscopy is a useful technique for determining variations in corrosion behavior across a surface. However, the numerous options for experimental parameters and little understanding of their effect on the corroding system render comparisons of results between studies difficult. Herein, we explore changes in corrosion behavior of two martensitic stainless steels, a cast CA6NM and a wrought S41500, as a result of the chosen experimental parameters, including scan rate, approach potential, surface oil immersion, and tip aperture diameter. The study demonstrates that these experimental parameters can be controlled to probe oxide passivation kinetics and single pitting events by changing the surface state and cathodic currents. We measured the pitting and repassivation kinetics of a single pit and determined the compositional change of the Al2O3 inclusion site initiation point. Hundreds of data points were measured within 17 h of experimental time on the stainless steel samples, allowing statistical averages of corrosion and pitting values. This work will open new avenues for fine-tuning various corrosion aspects at the microscale, thereby contributing to a deeper understanding of the corrosion processes and mechanisms of diverse materials.

Fracture ellipticity as a measure of chemical reaction-controlled fracture growth

Fracture ellipticity as a measure of chemical reaction-controlled fracture growth

Single Stage Nasal Reconstruction for Solitary Neurofibroma Isolated in the Columella.

Neurofibromas are benign peripheral nerve sheath tumors that can originate from several elements of peripheral nerves, including axons, Schwann cells, endoneurial fibroblasts, and perineurial cells. The occurrence of a solitary neurofibroma in the external nose, especially that isolated in the nasal columella, is extremely rare. To the best of our knowledge, only 4 cases of solitary neurofibromas in the external nose have been reported in the English literature: on the nasal dorsum, tip, and pyriform aperture, all originating from the trigeminal nerve. We report the first case of a solitary neurofibroma isolated in the nasal columella, which we found in an otherwise healthy 42-year-old man. We completely resected this tumor with a negative resection margin and performed reconstruction with a bilateral spreader graft and caudal septal extension graft using autologous septal cartilage. The postoperative course was successful in both cosmetic and functional results, with no sensory changes at the 1-year follow-up. Surgical treatment for this lesion was challenging due to the cosmetically obvious location and high rate of recurrence. A review of the literature highlights the clinical and histological characteristics, differential diagnosis, and management of solitary neurofibroma of the external nose.

Mechanism of near-field optical nanopatterning on noble metal nano-films by a nanosecond laser irradiating a cantilevered scanning near-field optical microscopy probe.

To overcome the diffraction limit, a laser irradiating cantilevered scanning near-field optical microscopy (SNOM) probe has been used in near-field optical nanopatterning. In this paper, the mechanism of nanopatterning on noble metal nano-films by this technique is investigated by the finite element method. It is proposed that the main mechanism of this phenomenon is the melt and reshaping of the nano-film under the SNOM tip. The melt is caused by the surface plasmon polariton-assisted enhancement and restriction within the SNOM tip aperture. The impacts of the gap g between the tip and substrate and the polarization of the laser are further analyzed.

Fabrication of nanostructure on Au nano-film by nanosecond laser coupled with cantilevered scanning near-field optical microscopy probe

Diffraction limit has been the constraint of the nanostructure fabrication. Because the scanning near-field optical microscopy (SNOM) can work in the evanescent near-field region, its application in nano-processing has received extensive attention from researchers globally. In this paper, we combined nanosecond laser with cantilevered SNOM probe. Utilizing the high precision of the confinement and enhancement effect of probe tip and the high instantaneous energy of the laser, we realized nanostructure fabrication and in situ detection on Au nano-film. Feature sizes down to 47 nm full width at half maximum were fabricated. We investigated the laser propagation through the SNOM tip aperture and the light field intensity distribution on the surface of substrate theoretically. The calculation results demonstrate that the laser is highly restricted within the SNOM aperture and enhanced on the exit plane at the rim of aperture. After the transmission, the light field intensity distribution on the surface of the Au nano-film was enhanced due to the localized surface plasmon resonance. The thermal distribution on the surface of Au nano-film indicates that the peak of the temperature distribution appeared at the surface right underneath the center of the aperture. It is proved that the simulation results are consistent with the experimental results.

Mechanism of nanostructure processing on Au and Ag nano-film by a nanosecond laser illuminating cantilevered scanning near-field optical microscopy tip.

Nanostructure processing by a laser illuminating cantilevered scanning near-field optical microscopy (SNOM) tip is a novel technology that has received extensive attention from researchers. In this paper, theoretical investigations of the mechanism for nanostructure fabrication on Au and Ag nano-film by this technology are realized by the finite element method. The light field intensity and temperature distribution on Au and Ag surfaces at the near-field of the SNOM tip apex after illumination is simulated. The results reveal that the laser is restricted and enhanced within the SNOM tip aperture during illumination. Locally excited surface plasmon polaritons, which induce near-field enhancement on the Au and Ag nano-film at the vicinity of the aperture, are significant for nanostructure fabrication. The impacts of several parameters such as aperture width w, gap between the apex and substrate g, and the initial electric field intensity |E0| of the laser on the temperature of the Au and Ag substrate surfaces during fabrication are deeply studied. It reveals that the surface temperature depends on both the enhancement of the light field intensity and the transmitted laser. The enhancement is dominant in affecting temperature when the gap is small, while the transmittance becomes the main factor influencing the surface temperature with the increase of the gap.

Near-field launching and mapping unidirectional surface plasmon polaritons using an automated dual-tip scanning near-field optical microscope

The spatial distribution of electromagnetic fields emitted from the aperture tip of a scanning near-field optical microscope (SNOM), which is called the emission pattern, depends on the geometry of the apex and the material composition of the tip’s coating. In previous works, experimental measurements of the emission pattern from the aperture tip were performed mostly in the far field. Moreover, the corresponding theoretical models were also developed based on these far-field measurements. Here, we have used the automated dual-tip SNOM to systematically characterize the emission from the aperture tip in the near field. In this regard, we have considered three different pairs of excitation and detection tips with distinct geometries. The emission patterns of the excitation tips were mapped using detection tips. Unidirectional surface plasmon polaritons (SPPs) at the surface of a gold platelet were launched by an excitation tip and measured in the near field by the detection tip. The experimental results were numerically reproduced by means of the Bethe–Bouwkamp model. This work puts into evidence the applicability of the automated dual-tip SNOM as the only available characterization technique to measure the emission from aperture tips in the near field. The reported asymmetric SPP radiation patterns can find applications in photonic integrated circuits or in biological and chemical sensing.

Near-field interference map due to a dipolar emission near the edge of a monocrystalline gold platelet

Point source excitation and point detection in the near-field provides new perspective to study the near-field optical phenomena of plasmonic nanostructures. Using the automated dual-tip scanning near-field optical microscope (SNOM), we have measured the optical near-field response of a dipolar emission near the edge of a monocrystalline gold platelet. The image dipole method was used to analytically calculate the interference pattern due to surface plasmon polaritons excited at the position of aperture tip and those reflected from edges of the gold platelet. The near-field enhancement was observed on the edges of the gold platelet. Our results verify that automated dual-tip SNOM is an intriguing technique for quantum plasmonic studies where deterministic coupling of quantum emitters and the detection of the near-field enhancement are of great interest.

Reconsidering lateral vocalisation: Evidence from perception and production of Australian English /l/.

Lateral vocalisation is assumed to arise from changes in coronal articulation but is typically characterised perceptually without linking the vocalised percept to a coronal articulation. Therefore, we examined how listeners' perception of coda /l/ as vocalised relates to coronal closure. Perceptual stimuli were acquired by recording laterals produced by six speakers of Australian English using electromagnetic articulography (EMA). Tongue tip closure was monitored for each lateral in the EMA data. Increased incidence of incomplete coronal closure was found in coda /l/ relative to onset /l/. Having verified that the dataset included /l/ tokens produced with incomplete coronal closure-a primary articulatory cue of vocalised /l/-we conducted a perception study in which four highly experienced auditors rated each coda /l/ token from vocalised (3) to non-vocalised (0). An ordinal mixed model showed that increased tongue tip (TT) aperture and delay correlated with vocalised percept, but auditors ratings were characterised by a lack of inter-rater reliability. While the correlation between increased TT aperture, delay, and vocalised percept shows that there is some reliability in auditory classification, variation between auditors suggests that listeners may be sensitive to different sets of cues associated with lateral vocalisation that are not yet entirely understood.

The arrest and recession dynamics of a deflating hydraulic fracture in a permeable elastic medium in a state of plane strain

We investigate the deflation dynamics of a fluid-driven fracture in a permeable elastic medium in a state of plane strain after fluid injection has ceased. Depending on the leak-off characteristics of the porous medium and the volume of injected fluid retained in the fracture at the time of shut-in, the fracture may start to recede almost immediately or continue to propagate till it arrests when the stress intensity factor drops below the fracture toughness. While occupying the arrest footprint, the fracture continues to deflate while the stress intensity factor decreases due to fluid loss to the porous medium. When the stress intensity factor drops to zero, the fracture starts the process of recession, which continues until it finally collapses. To establish a rigorous numerical scheme to explore the deflation dynamics of plane strain hydraulic fractures, we use recently established vertex and multiscale tip asymptotes for arrested and receding hydraulic fractures (Peirce and Detournay, 2022), including the r-vertex linear tip aperture asymptote wˆ∼xˆ for a receding hydraulic fracture and the stationary g-vertex asymptote wˆ∼xˆ3/4. Numerical experiments demonstrate that the multiscale asymptotes are required in order to achieve solutions that remain smooth through the arrest–recession transition point. In contrast, numerical solutions, obtained by only using vertex solutions to model the arrest and recession, exhibit jump discontinuities through this transition point. However, once the transients from these jump discontinuities have decayed the numerical schemes that use vertex and multiscale asymptotes yield almost identical solutions. A scaling analysis shows the existence of asymptotic power law behaviour for various quantities, such as the arrest time, in terms of two new dimensionless parameters. Finally, numerical solutions explore the dependence on the two dimensionless parameters of the arrest time, the duration of the arrest period, and the duration of the recession phase and confirm their asymptotic power law behaviours.

Micromachining of polymers using atmospheric pressure inductively coupled helium plasma localized by a scanning nanopipette probe microscope

We developed a local irradiation system for atmospheric pressure inductively coupled plasma (ICP) using a quartz capillary nozzle (nanopipette) with a sub-micrometer diameter tip aperture for fine processing of material surface. Using this system, a polymethyl methacrylate (PMMA) film coated on a glass substrate was etched at the micrometer scale. Fine etching was achieved by the ICP localized by the nanopipette precisely placed near the surface, using the positioning capability of a homemade scanning probe microscope. The locally etched surface of the PMMA film was confirmed by imaging immediately after the etching process by scanning the nanopipette. For quantitative evaluation, the topographical image of the same location of the surface was then acquired using an atomic force microscope. The etching rate of the ICP was 20 times higher than that of the low-frequency atmospheric pressure plasma jet. The depth of the etched holes increased with increasing applied power and irradiation time and decreasing irradiation distance. In addition, line groove patterning with sub-micrometer width was successfully achieved. The proposed system is expected to be used in various applications such as processing and repairing of microdevices.

Hydrodynamic impulse enhancement of a vortex ring interacting with an axisymmetric co-axial aperture

Abstract

Carbon tip aperture cantilevers: Fabrication & features in near-field magneto-optical imaging

Improving the ways of magnetic structure investigation with the lowest possible resolution is important in the study and practical implementation of fundamental magnetism. Here we discuss one of the most modern magneto-optical method of domain structure (DS) imaging, scanning near-field magneto-optical microscopy (SNMOM), and propose the new technology based on focused ion beam (FIB) treatment to produce aperture cantilevers with carbon hollow pyramid tip (ACCT). Estimated ACCT light transmission coefficients show better results compare to commonly used aperture silicon cantilevers. By measuring the polarization characteristics of aperture with diameter from 83 to 263 nm, we illustrate the possibility of ACCT to maintain a liner polarization of transmitted light. Testing of ACCT in atomic-force and SNMOM modes shows that ACCT are the effective tool in near-field imaging. Features of morphology and DS of Bi-substituted iron garnet (Bi: IG) films synthesized and used as the test objects, including DS peculiarities of 100 nm-size, is revealed.

Compensation of physiological motion enables high-yield whole-cell recording in vivo

BackgroundWhole-cell patch-clamp recording in vivo is the gold-standard method for measuring subthreshold electrophysiology from single cells during behavioural tasks, sensory stimulations, and optogenetic manipulation. However, these recordings require a tight, gigaohm resistance, seal between a glass pipette electrode's aperture and a cell's membrane. These seals are difficult to form, especially in vivo, in part because of a strong dependence on the distance between the pipette aperture and cell membrane. New MethodWe elucidate and utilize this dependency to develop an autonomous method for placement and synchronization of pipette's tip aperture to the membrane of a nearby, moving neuron, which enables high-yield seal formation and subsequent recordings deep in the brain of the living mouse. ResultsThis synchronization procedure nearly doubles the reported gigaseal yield in the thalamus (>3 mm below the pial surface) from 26 % (n = 17/64) to 48 % (n = 32/66). Whole-cell recording yield improved from 10 % (n = 9/88) to 24 % (n = 18/76) when motion compensation was used during the gigaseal formation. As an example of its application, we utilized this system to investigate the role of the sensory environment and ventral posterior medial region (VPM) projection synchrony on intracellular dynamics in the barrel cortex. Comparison with Existing Method(s)Current methods of in vivo whole-cell patch clamping do not synchronize the position of the pipette to motion of the cell. ConclusionsThis method results in substantially greater subcortical whole-cell recording yield than previously reported and thus makes pan-brain whole-cell electrophysiology practical in the living mouse brain.

Quantification and targeted detection of ciprofloxacin in dosage form and human urine by direct injection nano-electrospray ionization multi-stage mass spectrometry

A rapid, selective and sensitive direct infusion nano-electrospray ionization multi-stage mass spectrometry (DI-nano-ESI-MS3) method has been developed and validated for ciprofloxacin identification and quantification. An aliquot of 4 µl containing ciprofloxacin sample solution along with an internal standard (IS), in this case tamoxifen, was loaded into a nanospray (NS) capillary. The NS capillary was then fitted off-line into the ion source where the distance between NS capillary tip and MS aperture was set to 5 mm. The instrument was operated to acquire a two-minute run by applying a voltage of 1000 V (positive-ion detection mode). Ciprofloxacin quantification relied on the ratio of its parent peak (m/z 332) to the IS peak (m/z 372), while identification relied on MS3 of the parent peak and its fragments with m/z values of 314, 288, 268 and 245, respectively. Due to the observed ion suppression effect exerted by the IS over the analyte ion signal at lower concentration levels (< 500 ng/ml ciprofloxacin), the calibration curve was split into two sections. As a result, linearity correlation between the ratios of the analyte to the IS and the corresponding concentrations over the ranges 5–500 and 500–4000 ng/ml respectively was observed. The applicability of the developed method was confirmed by analyzing ciprofloxacin in a pharmaceutical dosage form as well as detection of the analyte in random human clinical urine samples after oral administration of the drug.

Scanning Near-Field Fluorescence Microscopy Applied to ESEM

A scanning near-field fluorescence microscopy for in situ test is demonstrated in this letter. The scanning near-field fluorescence microscopy can be applied to commercial environmental scanning electron microscopy (ESEM) without changing the ESEM performance. The designed scanning near-field fluorescence microscopy combines the advantage of the ESEM and scanning near-field optical microscopy (SNOM). The CdSe/ZnS quantum dot samples are prepared to verify system performance. The system offers fluorescence image and topography image simultaneously with a high depth and high resolution, thus permitting further ingredient and functional research. The topography image spatial resolution and the fluorescence image spatial resolution are below 130 nm and 115 nm, respectively, with a tip aperture of ~100 nm. The image range reaches $300\,\,\times \,\,300\,\,\mu \text{m}$ by virtue of the micromanipulators and image stitching technology.

Vortex ring impingement on a wall with a coaxial aperture

An investigation of the interaction of a vortex ring colliding with a coaxially aligned aperture, which extends the classical problem of a vortex ring impacting a solid wall, examines the behaviors of near-wall vortices in the proximity of a structural discontinuity (aperture tip).

One-Shot Measurement of the Three-Dimensional Electromagnetic Field Scattered by a Subwavelength Aperture Tip Coupled to the Environment

Near-field scanning optical microscopy (NSOM) achieves subwavelength resolution by bringing a nanosized probe close to the surface of the sample. This extends the spectrum of spatial frequencies that can be detected with respect to a diffraction limited microscope. The interaction of the probe with the sample is expected to affect its radiation to the far field in a way that is often hard to predict. Here we address this question by proposing a general method based on full-field off-axis digital holography microscopy which enables to study in detail the far-field radiation from a NSOM probe as a function of its environment. A first application is demonstrated by performing a three-dimensional (3D) tomographic reconstruction of light scattered from the subwavelength aperture tip of a NSOM, in free space or coupled to transparent and plasmonic media. A single holographic image recorded in one shot in the far field contains information on both the amplitude and the phase of the scattered light. This is suffi...

Near-Field Plasmonic Probe with Super Resolution and High Throughput and Signal-to-Noise Ratio

Near-field scanning optical microscopy (NSOM) enables observation of light-matter interaction with a spatial resolution far below the diffraction limit without the need for a vacuum environment. However, modern NSOM techniques remain subject to a few fundamental restrictions. For example, concerning the aperture tip (a-tip), the throughput is extremely low, and the lateral resolution is poor; both are limited by the aperture size. Meanwhile, with regard to the scattering tip (s-tip), the signal-to-noise ratio (SNR) appears to be almost zero; consequently, one cannot directly use the measured data. In this work, we present a plasmonic tip (p-tip) developed by tailoring subwavelength annuli so as to couple internal radial illumination to surface plasmon polaritons (SPPs), resulting in an ultrastrong, superfocused spot. Our p-tip supports both a radial symmetric SPP excitation and a Fabry-Pérot resonance, and experimental results indicate an optical resolution of 10 nm, a topographic resolution of 10 nm, a throughput of 3.28%, and an outstanding SNR of up to 18.2 (nearly free of background). The demonstrated p-tip outperforms state-of-the-art NSOM tips and can be readily employed in near-field optics, nanolithography, tip-enhanced Raman spectroscopy, and other applications.