Small Caliber Research Articles

Thrombogenicity Assessment of Perfusable Tissue-Engineered Constructs: A Systematic Review.

Vascular surgery is facing a critical demand for novel vascular grafts that are biocompatible and thromboresistant. This urgency is particularly applicable to bypass operations involving small caliber vessels. In the realm of tissue engineering, the development of fully vascularized organs is promising as a solution to organ shortage for transplantation. To achieve this, it is essential to (re)construct a biocompatible and nonthrombogenic vascular network within these organs. In this systematic review, we identify, classify, and discuss basic principles and methods used to perform in vitro/ex vivo dynamic thrombogenicity testing of perfusable tissue-engineered organs and tissues. We conducted a preregistered systematic review of studies published in the last 23 years according to PRISMA-P Guidelines. This comprised a systematic data extraction, in-depth analysis, and risk of bias assessment of 116 included studies. We identified shaking (n = 28), flow loop (n = 17), ex vivo (arteriovenous shunt, n = 33), and dynamic in vitro models (n = 38) as the main approaches for thrombogenicity assessment. This comprehensive review reveals a prevalent lack of standardization and provides a valuable guide in the design of standardized experimental setups.

Metalens-based hybrid probe near-infrared endoscope objective

Rapid large-area deep tissue imaging at long working distances is important for clinical diagnosis. A near-infrared metalens-based hybrid probe con-focal micro-endoscope (pCM) objective with a large field of view of 500 μm, a long working distance of 300 μm, and a small caliber of 2.2 mm was designed, which is compatible with conventional endoscopes to produce cell-resolution images of deep tissues. The performance of the metalens-based hybrid objective optical system was analyzed. Results show that the metalens-based hybrid pCM significantly improves the imaging quality of such optical systems under the premise of meeting the design accuracy requirements, which provides a new solution and an effective realization for the design of such optical systems.

Clinical and Radiographic Outcomes of Small Caliber Intramedullary Nails for Tibial Shaft Fractures.

Tibial shaft fractures, frequently treated with intramedullary nailing (IMN), are high-risk fractures of nonunion. The effect of intramedullary nail diameter on fracture union reduction remains an area of investigation, with many surgeons anecdotally preferring to place at least a 10-mm tibial nail. We hypothesized that small-caliber nails (SCNs) (diameter ≤9 mm) are safe to use and have no difference in complication rates compared with large-caliber nails (LCNs) (≥10 mm). A retrospective study was conducted on patients with tibial shaft fractures undergoing reamed IMN at a level 1 trauma center between 2018 and 2022. Patient and injury characteristics, intramedullary nail diameter, surgical details, and postoperative complication rates were recorded. Nail and intramedullary canal width at the isthmus on coronal radiographs determined the nail-canal ratio. Radiographic coronal and sagittal displacement, angulations between fracture segments, and coronal plane tibial mechanical axis were evaluated on latest radiographs. Among 113 patients, 68 received SCN while 45 received LCN. No difference was observed in the nail-canal ratio between the SCN and LCN groups, indicating that smaller nails were used for smaller canals. No significant demographic differences were noted between groups. LCNs were more prevalent in (AO Foundation/Orthopaedic Trauma Association classification) AO/OTA 42C (P = 0.03) and Gustilo-Anderson type III fractures (P = 0.05). The LCN group had higher rates of revision surgery (20% vs. 5.9%, P = 0.03) and wound dehiscence (8.9% vs. 0%, P = 0.02). Gustilo-Anderson IIIA fractures were independently associated with poorer outcomes overall. Radiographic parameters were comparable between groups. Small-diameter and large-diameter reamed intramedullary nails can be effective in treating tibial shaft fractures. Nail-canal ratios and alignment were similar between the two groups, suggesting that surgeons should not feel obligated to ream to a 10-mm nail in a smaller patient with a well-reduced fracture.

Distribution-free uncertainty quantification for inverse problems: Application to weak lensing mass mapping

In inverse problems, the aim of distribution-free uncertainty quantification (UQ) is to obtain error bars in the reconstruction with coverage guarantees that are independent of any prior assumptions about the data distribution. This allows for a better understanding of how intermediate errors introduced during the process affect subsequent stages and ultimately influence the final reconstruction. In the context of mass mapping, uncertainties could lead to errors that affect how the underlying mass distribution is understood or that propagate to cosmological parameter estimation, thereby impacting the precision and reliability of cosmological models. Current surveys, such as Euclid or Rubin will provide new weak lensing datasets of very high quality. Accurately quantifying uncertainties in mass maps is therefore critical to fully exploit their scientific potential and to perform reliable cosmological parameter inference. In this paper, we extend the conformalized quantile regression (CQR) algorithm, initially proposed for scalar regression, to inverse problems. We compared our approach with another distribution-free approach based on risk-controlling prediction sets (RCPS). Both methods are based on a calibration dataset, and they offer finite-sample coverage guarantees that are independent of the data distribution. Furthermore, they are applicable to any mass mapping method, including black box predictors. In our experiments, we applied UQ to three mass-mapping methods: the Kaiser-Squires inversion, iterative Wiener filtering, and the MCALens algorithm. Our experiments reveal that RCPS tends to produce overconservative confidence bounds with small calibration sets, whereas CQR is designed to avoid this issue. Although the expected miscoverage rate is guaranteed to stay below a user-prescribed threshold regardless of the mass mapping method, selecting an appropriate reconstruction algorithm remains crucial for obtaining accurate estimates, especially around peak-like structures, which are particularly important for inferring cosmological parameters. Additionally, the choice of mass mapping method influences the size of the error bars.

Research on electrolytic plasma polishing process for internal flow channel of superalloys alloy additive manufacturing parts

To solve the problem of poor surface quality of internal channel parts in additive manufacturing, the internal electrode electrolyte plasma polishing technology was used to improve the surface quality of the workpiece. The influence of different process parameters on the surface roughness of the internal channel was studied by orthogonal test. The experimental results show that for small caliber channels, polishing is more suitable for low voltage conditions. Under the conditions of polishing voltage 40 V, electrolyte temperature 80°C, moving speed of cathode wire 3 mm/min, and peristaltic pump speed 100 rpm, the roughness of the GH3536 inner channel sample is reduced from 15.1 to 2.793 μm. The order of influence of each factor is as follows: firstly voltage, secondly electrolyte temperature, then cathode wire traveling speed, and finally peristaltic pump speed. The roughness of GH4169 was reduced from 6.724 to 0.47 μm by polishing experiment. The results of the internal surface performance test show that the spherical powder on the surface of the workpiece disappears after polishing through the internal flow channel, the electrolyte component residue is not detected on the surface of the internal flow channel, and the corrosion resistance is significantly improved.

Evaluation of normalization methods applied to Short-Wavelength Infrared (SWIR) spectroscopy mineral databases from multiple instruments and for vectoring analysis exploration

Over the past decade, short-wave infrared (SWIR) spectroscopy has made significant advances in detecting geochemical variations in minerals like white mica, alunite, and chlorite for exploring hydrothermal ore deposits. These variations provide valuable clues, indicating changes in temperature, pH, and fluid oxidation state towards the mineralized center. However, small calibration differences among devices challenge data integration. This study evaluates the 2200 nm Al-OH absorption feature in four white mica SWIR spectroscopy databases collected by TerraSpec™ and OreXpress™ from samples at the Grasshopper porphyry prospect. It evaluates three normalization methodologies: rescaling, mean normalization, and Z-score, yielding p-values for successful data merging of up to 0.75. Findings suggest effective normalization methods across devices, reducing biases from uncalibrated spectrometers. This research offers a methodology to correct SWIR database biases, facilitating accurate data integration across instruments for vectoring analysis.

Design of a small gas flow calibration facility by piston prover method

Design of a small gas flow calibration facility by piston prover method

Remote Sensing Estimation of Shallow and Deep Aquifer Response to Precipitation‐Based Recharge Through Downscaling

AbstractThe Gnangara groundwater system is a highly productive water resource in southwestern Australia. However, it is considered one of the most vulnerable groundwater systems to climate change, due to consistent declines in precipitation and recharge, and regional climate models project further declines into the future. This study introduces a new framework underpinned by machine learning techniques to provide reliable estimates of precipitation‐based recharge over the whole Perth Basin (including the Gnangara system). By combining estimates of baseflow, groundwater evaporation, and extraction, groundwater recharge was estimated over the Perth (testing site) and Gnangara (calibration site) systems using downscaled Groundwater Storage Anomalies (GWSA) from the Gravity Recovery and Climate Experiment (GRACE) mission. The random forest regression (RFR) model was used to downscale the spatial resolution of GRACE to 0.05° (approx. 5 km), providing estimable signals over the relatively small calibration site (∼2,200 km2) in order to discern any meaningful signals from the original GRACE resolution. Our study reveals that downscaled signals from GRACE can be used to provide precipitation‐based recharge estimates for groundwater systems accurately. However, the growing impacts of climate change, which has led to sporadic precipitation patterns over Western Australia, can limit the efficiency of satellite remote sensing methods in estimating recharge, especially in deep and complex aquifers.

High‐Q LNA With a VCO for Small Calibration Frequency Errors

ABSTRACTA high‐quality (Q) low‐noise amplifier (LNA) combined with a voltage‐controlled oscillator (VCO) is presented for small frequency errors in self‐calibration. The proposed new double capacitive‐cross‐coupled structure controls negative impedance and thus, changes the working mode between the LNA and VCO with a small variation of parasitic capacitance, which results in a small calibration frequency error. High‐Q and low‐noise performances were theoretically analyzed and confirmed by simulation and measurement. The measured LNA operated from 2.2 to 2.44 GHz with a Q‐factor of 34 while the frequency offset was less than 0.9%. A power gain of 27 dB, noise figure of 2.1 dB, and input third‐order intercept point (IIP3) of −17 dBm were obtained while the power dissipations of the LNA and VCO modes were 10.2 and 4.7 mW from a 1.5‐V supply, respectively.

Optimization of Temperature Measurement Method for High-Pressure Gas Flow Standard Facility Based on Sonic Nozzle Array

To improve the accuracy of the wind tunnel test, relying on the high-pressure gas source of the China Aerodynamic Research and Development Center, a secondary flow standard facility based on a sonic nozzle array was developed, with a pressure range of (1~6) MPa and a flow range of (0.12~5.55) kg/s. Currently, most facilities use the average temperature measured by the temperature array to represent the upstream temperature of the sonic nozzle array. However, the small flow calibration test results showed that the maximum temperature difference upstream of the standard sonic nozzle array was 1.97 K, and the temperature field upstream of the sonic nozzle array showed non-uniformity, so the above method cannot accurately obtain the upstream temperature. To solve this problem, each nozzle used in the standard sonic nozzle array was accurately measured by temperature sensors. The uncertainty of the facility and the discharge coefficient of the calibrated nozzle between the two methods were compared. The results showed that compared with the discharge coefficient obtained using the temperature sensor array of 0.9902, the accurate measurement of 0.9904 was closer to the National Institute of Metrology, China (NIM) traceable result of 0.9907, and the relative uncertainty of the facility was reduced from 0.124% (k = 2) to 0.120% (k = 2).

Ridgecrest Aftershock Stress Drops from P- and S-Wave Spectral Decomposition

ABSTRACT Seismic moment and stress drop are crucial for understanding earthquake rupture processes, but their estimates often have large uncertainties for small earthquakes. Stress drop is typically inferred from an earthquake’s source spectrum based on theoretical models, but poorly constrained path corrections and other modeling assumptions limit the accuracy of stress-drop estimates. Here, we compute stress drops using both P and S waves for the 2019 Ridgecrest earthquake sequence, compare their estimates, and evaluate the associated uncertainties. We use spectral decomposition and apply the analysis to both types of waves for the same set of earthquakes, adjusting some S-wave parameter choices to obtain overall consistency with our P-wave results. Our approach fixes the corner frequency of small calibration earthquakes to reduce scatter in the estimated source parameters of the larger earthquakes. We find that assuming a lower high-frequency fall-off rate for S waves yields more consistent absolute stress-drop estimates between P and S waves. Our stress-drop estimates appear to increase slightly with magnitude for earthquakes with magnitudes >∼3.4. Furthermore, we find that the stress-drop estimates using both types of data exhibit coherent spatial variations. Earthquakes near the Coso geothermal field tend to have lower stress drops, and earthquakes near the M 7.1 hypocenter have higher stress-drop estimates. This spatial pattern is consistently observed in both the P- and S-wave results. We find no strong correlation between our stress-drop estimates and the M 7.1 Ridgecrest earthquake slip distribution, suggesting a heterogeneous stress environment for the Ridgecrest fault system.

Biliary Complications after Liver Transplant: Imaging Review and Minimally Invasive Management

AbstractWith the advent of living donor liver transplant, the waiting list mortality of patients needing liver transplant has decreased. However, increased morbidity is observed, including higher rates of biliary complications (BCs). Strictures and postoperative leaks constitute the majority of the BCs. Various factors such as multiple biliary ducts anastomosis and small caliber ducts in the bile ducts increase the risk of biliary strictures. The lack of biliary dilation in the graft livers after liver transplant makes the recognition of biliary complications challenging and the diagnosis relies on abnormal liver function tests. Magnetic resonance cholangiopancreaticography provides a valuable means to assess the biliary anatomy prior to interventions by showing the level of stricture. While endoscopic retrograde cholangiopancreatography is considered the first modality to treat biliary strictures, those patients with proximal strictures and those with complex biliary anatomy with acute angulations between the donor and the recipient show poor response to endoscopic interventions. In such patients, percutaneous biliary interventions have success rates between 70 and 90%. Novel percutaneous biliary intervention techniques such as cholangioscopy-assisted laser incision and magnetic compression anastomosis are used to navigate difficult biliary strictures. Recently, biodegradable stents have been used to treat recalcitrant biliary strictures. In this review, we present the imaging features of common biliary complications following liver transplant and percutaneous biliary interventions in managing these complications.

An organotypic atlas of human vascular cells

The human vascular system, comprising endothelial cells (ECs) and mural cells, covers a vast surface area in the body, providing a critical interface between blood and tissue environments. Functional differences exist across specific vascular beds, but their molecular determinants across tissues remain largely unknown. In this study, we integrated single-cell transcriptomics data from 19 human organs and tissues and defined 42 vascular cell states from approximately 67,000 cells (62 donors), including angiotypic transitional signatures along the arterial endothelial axis from large to small caliber vessels. We also characterized organotypic populations, including splenic littoral and blood–brain barrier ECs, thus clarifying the molecular profiles of these important cell states. Interrogating endothelial–mural cell molecular crosstalk revealed angiotypic and organotypic communication pathways related to Notch, Wnt, retinoic acid, prostaglandin and cell adhesion signaling. Transcription factor network analysis revealed differential regulation of downstream target genes in tissue-specific modules, such as those of FOXF1 across multiple lung vascular subpopulations. Additionally, we make mechanistic inferences of vascular drug targets within different vascular beds. This open-access resource enhances our understanding of angiodiversity and organotypic molecular signatures in human vascular cells, and has therapeutic implications for vascular diseases across tissues.

Static and dynamic cell culture of small caliber bilayer vascular grafts electrospun from polycaprolactone

Developing a suitable vascular graft to replace damaged small-caliber vessels and promote tissue regeneration is a critical challenge. This study focuses on bilayer polycaprolactone (PCL) grafts, fabricated by electrospinning, with both randomly distributed and radially oriented fibers. The analysis covers surface morphology, fiber diameter, pore size, cellular behavior, and biodegradability. Human umbilical vein endothelial cells (HUVECs) show an impressive viability of 142.2% after 7 days, while umbilical artery smooth muscle cells (UASMCs) exhibit 112.6%. Fluorescent microscopy indicates a higher viability of HUVECs over UASMCs. On the other hand, less than 10% of HUVECs and less than 5% of UASMCs undergo cell death within 7 days. Biodegradation analysis over 12 months shows a significant weight loss of 65–70% for both types of fiber arrangements. A custom-designed bioreactor enables dynamic cell culture, revealing comparable activity to static cultures. In the dynamic cell culture environment, HUVECs maintain high viability and display robust proliferation at both the 4th and 7th days, supporting the results observed in static cell cultures. These findings underscore the significant potential of bilayer PCL grafts in advancing the field of blood vessels, offering promising avenues for the development of functional vascular replacements with enhanced regenerative capabilities.

Sequential Scan-Based Single-Dimension Multi-Voxel System Matrix Calibration for Open-Sided Magnetic Particle Imaging.

Open-sided magnetic particle imaging (OS-MPI) has garnered significant interest due to its potential for interventional applications. However, the system matrix calibration in OS-MPI using sequential scans is a time-consuming task and susceptible to the low signal-to-noise ratio (SNR) resulting from the small calibration sample size. These challenges have hindered the practical implementation of system matrix-based reconstruction for sequentially scanned OS-MPI. To address these issues, we propose a novel calibration method, named sequen- tial scan-based single-dimension multi-voxel calibration (SS-SDMVC), to efficiently obtain a high-SNR system matrix. This method was implemented in a cylindrical field of view (FOV), where a bar calibration sample parallel to the field-free line (FFL) was shifted along a fixed radial direction. A standard image reconstruction process was also introduced to verify the feasibility of SS-SDMVC. Through simulations, we analyzed the effects of noise levels and scanner imperfections on the SS-SDMVC-based reconstruction and demonstrated its robustness. In experiments, we compared the imaging performance of SS-SDMVC and the sequential scan-based traditional cubic-FOV SMC. The results showed that SS-SDMVC reduced the number of measurements by a factor of 210.94 and achieved higher reconstruction quality. Therefore, SS-SDMVC is expected to improve the reconstruction quality of human- scale or high-gradient FFL MPI scanners.

Effects of Ethanol Locks on Burst Pressure for Small Caliber Nonpower Injectable Peripherally Inserted Central Catheters.

Effects of Ethanol Locks on Burst Pressure for Small Caliber Nonpower Injectable Peripherally Inserted Central Catheters.

The Vecta 46 intermediate catheter for mechanical thrombectomy of distal medium vessel occlusions: A single-center experience.

With emerging evidence supporting the clinical efficacy and safety of mechanical thrombectomy (MT) for distal medium vessel occlusions (DMVOs), MT devices specifically designed to navigate through smaller caliber and more delicate tortuous distal cerebrovasculature are required. This study describes our single-center experience using the AXS Vecta 46 intermediate catheter for first-line thromboaspiration of DMVOs. We identified all patients who underwent MT using the Vecta 46 for first-line thromboaspiration for primary or secondary DMVOs. We collected baseline clinical data, angiographic and clinical outcomes, as well as procedural complications. The primary outcome in question was the rate of successful recanalization, which was defined as a modified Thrombolysis in Cerebral Infarction score of ≥2b. We identified 43 patients who underwent MT using the Vecta 46 catheter for thromboaspiration of 54 DMVOs. Intervened vessels included the M2 (23/54), M3 (19/54), and M4 (6/54) branches of the middle cerebral artery, A2 (1/54), A3 (1/54), and A4 (1/54) branches of the anterior cerebral artery, and P1 (1/54), P2 (1/54), and P4 (1/54) branches of the posterior cerebral artery. The median number of passes for primary DMVOs was 2 (IQR: 1-3) and 1 (IQR: 1-1.25) for secondary DMVOs. The rate of successful recanalization was 100% (18/18) for primary DMVOs and 80.6% (29/36) for secondary DMVOs. First-pass effect (FPE) was noted in 55.6% (30/54) of all primary and secondary DMVO cases. Improved short-term clinical outcomes were observed in both the primary (National Institute of Health Stroke Scale [NIHSS] shift: -5 [IQR: -14.25 to -0.25]) and secondary (NIHSS shift: -5 [IQR: -10 to -2]) DMVO groups. A total of six patients died during their hospitalization, though none were deemed procedural-related. Our study demonstrates the safety and efficacy of the Vecta 46 intermediate catheter for thromboaspiration of both primary and secondary DMVOs, achieving high rates of successful recanalization and FPE.

Postdissection Abdominal Aorto-Iliac Aneurysm Open Repair: A Surgical Technique Description and Systematic Review of the Literature

Postdissection abdominal aortic aneurysms (pDAAA) may develop in up to 7% of patients affected by aortic dissection. However, there is no consensus on the optimal management. Different endovascular and open surgical techniques have been reported. This case series describes the open surgical technique employed at a tertiary vascular surgery center to manage this complex pathology to allow future treatment of the visceral aorta if needed. A systematic review of the relevant literature on surgical and endovascular management of pDAAA was conducted. Consecutive patients surgically treated at a single center for pDAAA metachronous to a Stanford type A or type B aortic dissection from January 2018 to March 2023 were retrospectively retrieved. The surgical technique we employed entails the use of large-diameter bifurcated grafts (≥9mm branches) with longer main body, fenestration of the septum at renal arteries ostia and landing on a common femoral artery in case of small caliber iliac arteries (<8mm) to provide a suitable landing zone and access route for future endovascular thoracoabdominal repair in case of subsequent aneurysmal degeneration. The primary outcome was 30-day mortality. Secondary outcomes were major complications, late mortality, aortic-related mortality, and aortic-related reinterventions. Then, a systematic review of the literature until March 2023 was conducted. Five patients were included, all males with a mean age of 61years. The 30-day mortality was 0. One patient suffered from postoperative acute kidney injury and acute distress respiratory syndrome, and another one underwent repeat laparotomy for abdominal seroma. The mean follow-up was 44months with no aortic-related reinterventions to date. One patient died from nonaortic-related causes 9months after surgery. Open repair of pDAAA appears to be an effective treatment in selected patients, with low mortality rates, and technical choices should consider future endovascular treatment of the thoracoabdominal aorta.

An evaluation of source-blending impact on the calibration of SKA EoR experiments

ABSTRACT Twenty-one-centimetre signals from the Epoch of Reionization (EoR) are expected to be detected in the low-frequency radio window by the next-generation interferometers, particularly the Square Kilometre Array (SKA). However, precision data analysis pipelines are required to minimize the systematics within an infinitesimal error budget. Consequently, there is a growing need to characterize the sources of errors in EoR analysis. In this study, we identify one such error origin, namely source blending, which is introduced by the overlap of objects in the densely populated observing sky under SKA1-Low’s unprecedented sensitivity and resolution, and evaluate its two-fold impact in both the spatial and frequency domains using a novel hybrid evaluation (HEVAL) pipeline combining end-to-end simulation with an analytic method to mimic EoR analysis pipelines. Sky models corrupted by source blending induce small but severe frequency-dependent calibration errors when coupled with astronomical foregrounds, impeding EoR parameter inference with strong additive residuals in the two-dimensional power spectrum space. We report that additive residuals from poor calibration against sky models with blending ratios of 5 and 0.5 per cent significantly contaminate the EoR window. In contrast, the sky model with a 0.05 per cent blending ratio leaves little residual imprint within the EoR window, therefore identifying a blending tolerance at approximately 0.05 per cent. Given that the SKA observing sky is estimated to suffer from an extended level of blending, strategies involving de-blending, frequency-dependent error mitigation, or a combination of both, are required to effectively attenuate the calibration impact of source-blending defects.

Numerical Analysis of Small Caliber Spinning Projectile with Variety Boattail Configurations

Range extension has received great interest in the field of artillery and spinning projectiles. Reducing base drag is an effective way for rang extension, because it is a major component in transonic and supersonic Mach numbers. Boattailing is considered as one of the most implemented techniques to reduce base drag. This work uses variety of passive drag reduction techniques over M33 .50cal projectile. Multiple design variations on projectile boattail are considered. This includes varying boattail angle, use of riblets, and use of arced boattail. Computations are conducted using computational fluid dynamics by solving RANS equations. Simulations are performed over Mach numbers from 0.6 to 2.5. The aim of the simulations is to calculate most affecting aerodynamic forces and moments which include drag force, lift force, Magnus force, Magnus moment, overturning moment, and spin damping moment. Then these coefficients are compared for all design variations. Results are validated by comparing with experimental and numerical results from the literature. Furthermore, a mesh independence study is done for verification. It was found that every configuration has good performance at a certain speed range with regard to zero yaw drag and significant yaw drag reduction for riblets boattail for low supersonic speeds.