Hierarchically structured materials, inspired by sophisticated structures found in nature, are finding increasing applications in a variety of fields. Here, we describe the fabrication of wrinkled gold nanoparticle films, which leverage the structural tunability of gold nanoparticles to program the wavelength and amplitude of gold wrinkles. We have carefully examined the structural evolution and tuning of these wrinkled surfaces through varying nanoparticle parameters (diameter, number of layers, density) and substrate parameters (number of axes constrained during wrinkling) through scanning electron microscopy and cross-sectional transmission electron microscopy. It is found that nanoparticle layers of sufficient density are required to obtain periodical wrinkled structures. It was also found that tuning the nanoparticle diameter and number of layers can be used to program the wrinkle wavelength and amplitude by changing the film thickness and mechanical properties. This dual degree of tunability, not previously seen with continuous films, allows us to develop one of the smallest wrinkles developed to date with tunability in the sub-100 nm regime. The effect of the induced structural tunability on the enhancement of the intensity of the 4-mercaptopyridine Raman spectra is also studied through the application of these devices as substrates for surface-enhanced Raman spectroscopy (SERS), where wrinkling proves to be an effective method for enhancing the SERS signal in cases where there is an inherently low density of gold nanoparticles.
Three-dimensional electrodes that are controllable over multiple lengthscales are very important for use in bioanalytical systems that integrate solid-phase devices with solution-phase samples. Here we present a fabrication method based on all-solution-processing and thin film wrinkling using smart polymers that is ideal for rapid prototyping of tunable three-dimensional electrodes and is extendable to large volume manufacturing. Although all-solution-processing is an attractive alternative to vapor-based techniques for low-cost manufacturing of electrodes, it often results in films suffering from low conductivity and poor substrate adhesion. These limitations are addressed here by using a smart polymer to create a conformal layer of overlapping wrinkles on the substrate to shorten the current path and embed the conductor onto the polymer layer. The structural evolution of these wrinkled electrodes, deposited by electroless deposition onto a nanoparticle seed layer, is studied at varying deposition times to understand its effects on structural parameters such as porosity, wrinkle wavelength and height. Furthermore, the effect of structural parameters on functional properties such as electro-active surface area and surface-enhanced Raman scattering is investigated. It is found that wrinkling of electroless-deposited thin films can be used to reduce sheet resistance, increase surface area, and enhance the surface-enhanced Raman scattering signal.
Objective: The objective of this study is to determine the characteristics and frequency of intraoperative safety threats and resilience supports using a human factors measurement tool. Background: Human factors analysis can provide insight into how system elements contribute to intraoperative adverse events. Empiric evidence on safety threats and resilience in surgical practice is lacking. Methods: A cross-sectional study of 24 patients undergoing elective laparoscopic general surgery at a single center in the Netherlands from May to November, 2017 was conducted. Video, audio, and patient physiologic data from all included procedures were obtained through a multichannel synchronized recording device. Trained analysts reviewed the recordings and coded safety threats and resilience supports. The codes were categorized into 1 of 6 categories (person, task, tools and technology, physical environment, organization, and external environment). Results: A median of 14 safety threats [interquartile range (IQR) 11-16] and 12 resilience supports (IQR 11-16) were identified per case. Most safety threat codes (median 9, IQR 7-12) and resilience support codes (median 10, IQR 7-12) were classified in the person category. The organization category contained a median of 2 (IQR 1-2) safety threat codes and 2 (IQR 2-3) resilience support codes per case. The tools and technology category contributed a small number of safety threats (median 1 per case, IQR 0-1), but rarely provided resilience support. Conclusions: Through a detailed human factors analysis of elective laparoscopic general surgery cases, this study provided a quantitative analysis of the existing safety threats and resilience supports in a modern endoscopic operating room.
Fully-integrated electro-fluidic systems with micro-/nano-scale features have a wide range of applications in lab-on-a-chip systems used for biosensing, biological sample processing, and environmental monitoring. Rapid prototyping of application-specific electro-fluidic systems is envisioned to facilitate the testing, validation, and market translation of several lab-on-a-chip systems. Towards this goal, we developed a rapid prototyping process for creating wrinkled micro-/nano-textured electrodes on shrink memory polymers, fabricating microfluidics using molds patterned by a craft-cutter, and bonding electrical and fluidic circuitries using a PDMS partial curing method optimized for creating void-free bonds at the side walls and surfaces of tall (>5 μm) micro-/nano-textured wrinkled electrodes. The resulting electro-fluidic devices, featuring closely spaced high topography electrodes for electrochemical analysis, can withstand flow-rates and burst pressures larger than 25 mL min(-1) and 125 kPa, respectively. In addition, the fully-integrated electrochemical flow-cell developed here demonstrates excellent electrochemical behaviour, with negligible scan to scan variation for over 100 cyclic voltammetry scans, and expected redox signatures measured under various voltage scan rates and fluidic flow rates.
Introduction: The Revised Organ Injury Scale (OIS) of the American Association for Surgery of Trauma (AAST) is the most widely accepted classification of splenic trauma. The objective of this study was to evaluate inter-rater agreement for CT grading of blunt splenic injuries. Methods: CT scans in adult patients with splenic injuries at a level 1 trauma centre were independently graded by 5 fellowship trained abdominal radiologists using the AAST OIS for splenic injuries – 2018 revision. The inter-rater agreement for AAST CT injury score, as well as low-grade (IIII) versus high-grade (IV-V) splenic injury was assessed. Disagreement in two key clinical scenarios (no injury versus injury, and high versus low grade) were qualitatively reviewed to identify possible sources of disagreement. Results: A total of 610 examinations were included. The inter-rater absolute agreement was low (Fleiss kappa statistic 0.38, P < 0.001), but improved when comparing agreement between low and high grade injuries (Fleiss kappa statistic of 0.77, P < .001). There were 34 cases (5.6%) of minimum two-rater disagreement about no injury vs injury (AAST grade ≥ I). There were 46 cases (7.5%) of minimum two-rater disagreement of low grade (AAST grade I-III) versus high grade (AAST grade IV-V) injuries. Likely sources of disagreement were interpretation of clefts versus lacerations, peri-splenic fluid versus subcapsular hematoma, application of adding multiple low grade injuries to higher grade injuries, and identification of subtle vascular injuries. Conclusion: There is low absolute agreement in grading of splenic injuries using the existing AAST OIS for splenic injuries.
Aims and Background The spleen is the most frequently injured solid organ after blunt trauma and a trial non-operative management (NOM) has become the standard of care in hemodynamically stable patients. It remains uncertain which patients are at increased risk of non-operative management failure (NOMF) at initial presentation. We explored whether clinical variables including the contemporary rotational thromboelastography (ROTEM) parameters are predictive of NOMF. Materials and Methods Data for all adult patients with a blunt splenic injury was collected retrospectively at St. Michael’s Hospital in Toronto, Canada between 2005 and 2021. Those who underwent a splenectomy within 4 hours of presentation were classified as direct operative management (OM), while those who had a splenectomy after 4 hours of observation were classified as NOM failure. Vital signs on arrival and injury characteristics were collected. Logistic regression was used to identify predictors of OM and predictors of NOM failure. Results Seven hundred and seventeen patients were identified with splenic injury during our study period. The median Injury Severity Score (ISS) was 27 (IQR 17–36), and 19% ( n = 134) had a shock index of 1 or more. One hundred and eleven (15.5%) underwent direct operative management. A shock index above 1 and increasing spleen injury severity were strong predictors of patients undergoing direct OM. The remaining 606 patients underwent NOM of which 59% ( n = 357) of these were admitted to the ICU. NOM failure occurred in 7.4% ( n = 45) with a median time to NOM failure of 23 (IQR 8–72) hours. The American Association for the Surgery of Trauma (AAST) spleen injury severity was the major factor significantly associated with NOM failure. Conclusions The only major predictor of NOMF available on arrival is increased spleen injury grade. Other clinical variables such as age, vital signs on arrival, and bloodwork were not significantly able to predict NOM failure. Additional investigation is required to identify novel predictors of NOM failure.
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