Tip End Research Articles

Bottom, Top, or in Between: Combining Plasmonic Nanohole Arrays and Hydrogel Microgels for Optical Fiber Sensor Applications

AbstractAttractive label‐free plasmonic optical fiber sensors can be developed by cleverly choosing the arrangement of plasmonic nanostructures and other building blocks. Here, the final response depends very much on the alignment and position (stacking) of the individual elements. In this work, three different types of fiber optic sensing geometries fabricated by simple layer‐by‐layer stacking are presented, consisting of stimulus‐sensitive poly‐N‐isopropylacrylamide (polyNIPAM) microgel arrays and plasmonic nanohole arrays (NHAs), namely NHA/polyNIPAM, polyNIPAM/NHA, polyNIPAM/NHA/polyNIPAM. Their optical response to a representative stimulus, namely temperature, is investigated. NHA/polyNIPAM monitors the volume phase transition of polyNIPAM microgels through changes in the spectral position and the amplitude of the reflection minimum of plasmonic NHA. In contrast, polyNIPAM/NHA shows a more complex response to the swelling and collapse of polyNIPAM microgels in their reflectance spectra. The most pronounced changes in optical response are observed by monitoring the amplitude of the reflectance minimum of this sensor during heating/cooling cycles. Finally, the triple stack of polyNIPAM/NHA/polyNIPAM at the end of a optical fiber tip combines the advantages of the NHA/polyNIPAM, polyNIPAM/NHA double stacks for optical sensing. The unique layer‐by‐layer stacking of microgel and nanostructure is customizable and can be easily adopted for other applications.

A disposable envelope for video-assisted intubating stylet during tracheal intubation in COVID-19 pandemic.

DEAR EDITOR, Tracheal intubation of patients with coronavirus disease-19 (COVID-19) is a potentially aerosol-generating procedure that requires a careful and efficient approach to ensure the safety of both patients and healthcare providers.1 Many guidelines recommend the use of video-assisted intubating devices (VAIDs) to increase the operator’s distance from the patient’s airway and the chance of first-pass success.2 When donned with personal protective equipment (PPE), the first-pass success rate and intubation time with VAIDs are not affected when compared with a direct laryngoscope.3 A VAID is usually a video laryngoscope or video intubating stylet. It mainly composes of four parts: monitor, main body, handle and its cable, and a blade or stylet. Compared with the traditional direct laryngoscope, VAIDs can be expensive to use and maintain with concerns for cost-effectiveness, quality, and environmental impact from the disposable blades or stylets. Moreover, the nondisposable parts of the equipment such as the handle, cable, and main body can be potential sources of cross-contamination if strict decontamination is not followed.4 An innovative and economic approach is to cover the entire VAID device with a disposable envelope, including the optic stylet, handle, and monitor during airway management. We explored this concept using a video optic intubating stylet (disposcope endoscope). An elastic, flexible heat-shrunk tube was designed and manufactured, which the optic style can be inserted easily without any lubricant. The end tip of the heat-shrunk tube consists of a transparent acrylic lens that does not block or in any way compromise the light and camera of the optic stylet. The handle is then covered by a disposable plastic drape. This setup ensures the video optic stylet is fully shielded during airway management or tracheal intubation. The demonstration is provided by supplementary appendix (https://youtu.be/XBh1W5Rki8k). After each procedure, the heat-shrunk tube and the plastic handle drape can be removed and disposed of. The heat-shrunk tube is very thin (thickness in 1.5 mm). After its fitting over the optic stylet, it still allows the loading of endotracheal tube equal to or larger than 5.5 ID in size. A pediatric optic stylet with a matching heat-shrunk tube is also developed, and it can be loaded with an endotracheal tube equal to or larger than 3 ID in size. The COVID-19 pandemic is not likely going to disappear and can potentially become a seasonal or endemic foe. Furthermore, infected asymptomatic and mildly symptomatic still confer a high risk of transmission. Routine and emergent airway management thus poses the risk of potential exposure and infection to healthcare workers during the procedure and postoperative decontamination.5 An affordable and practical disposable barrier method to the video-assisted airway device to protect the operators and reduce the associated cost.

Design and analysis of front spar wing-tip segment for a small transport aircraft

Structural safety is an important aspect of the design of airframes. The spar is one of the critical structural elements of the airframe. The wing is subjected to bending due to shear loads caused by aerodynamic pressure, it undergoes compression and tension. This paper deals with the design of a segment of the front spar spanning from wing mid-section to the tip end on strength of materials approach. The load on the spar segment will be considered from a global wing stress analysis. Typical elliptical load distribution on the transport aircraft is considered. The wing is a statically indeterminate structure, the cross-section of a typical wing section is assumed and the maximum bending moment load case I s considered for wing stress analysis. The spar tip segment will be designed so it does not suffer any permanent deformation under the design limit load. Global finite element stress analysis will be carried out to check the validation of the design. Usually, a thumb rule assumption is made that spar takes a definite percentage of load but in this paper, the load acting on the spar is just not a mere assumption but a different approach called the ‘W/I method’. The spar tip segment is designed based on the load magnitude and distribution using the strength of materials approach.

Strategies for extended lifetime of implantable intraperitoneal insulin catheters

Implantable insulin infusion systems using the intra-peritoneal route have dramatically changed the management of diabetes paving the way toward the realization of the potential “holy grail” of a fully implantable artificial pancreas. However, the wear duration of delivery catheters is compromised by the foreign body-mediated immune response. Both occlusion material present at the distal catheter tip end and fibrotic encapsulation surrounding the catheters influence the controlled and precise delivery of insulin, which eventually leads to the need for surgical intervention. The novel part of the current work is the investigation of the roles of implant physical properties (catheter size and tip configuration), as well as local inflammation control (through utilization of an anti-inflammatory agent) on the host fibrotic response using a previously developed animal model. The cellular and molecular response, the medication delivery efficacy as well as the ability to flush the catheters were examined and further compared among the different mitigation strategies. Reduction in catheter size as well as tuning the tip configuration from a cone shape to a round shape showed delayed host recognition and delayed propagation of the fibrotic response. However, the round shaped tips had an increased occurrence of lumen occlusion as a result of flow change. It became apparent that changing the physical properties of the catheters was not a long-term solution to catheter obstructions caused by the foreign body reaction. In comparison, control of the local inflammatory response through the use of an anti-inflammatory agent demonstrated a promising strategy for maintenance of catheter functionality without any type of obstructions. These finding will have a large impact toward the development of long-term use catheters for continuous intraperitoneal insulin infusion.

The role of direct peritoneal resuscitation in the treatment of hemorrhagic shock after trauma and in emergency acute care surgery: a systematic review.

Direct peritoneal resuscitation (DPR) has been used to help preserve microcirculation by reversing vasoconstriction and hypoperfusion associated with the pathophysiological process of shock, which can occur despite appropriate intravenous resuscitation. This approach depends on infusing a hyperosmolar solution intraperitoneally via a percutaneous catheter with the tip ending near the pelvis or the root of the mesentery. The abdomen is usually left open with a negative pressure abdominal dressing to continuously evacuate the infused dialysate. Hypertonicity of the solution triggers visceral vasodilation to help maintain blood flow, even during shock, and is also associated with reduced local inflammatory cytokines and other mediators, preservation of endothelial cell function, and mitigation of organ edema and necrosis. It also has a direct effect on liver perfusion and edema, more rapidly corrects electrolyte abnormalities compared to intravenous resuscitation alone, and may requireless intravenous fluid to stabilize blood pressure, all of which shortens the time required to close patients' abdomen. An online query using the search term "direct peritoneal resuscitation" was carried out in PubMed, MEDLINE and SciELO, limited to publications indexed from January 2014 to June 2020. Of the 20 articles returned, full text was able to be obtained for 19. A manual review of included articles' references was resulted in the addition of 1 article, for a total of 20 included articles. The 20 articles were comprised of 15 animal studies, 4 clinical studies,and 1 expert opinion. The benefits include both local and possibly systemic effects on perfusion, hypoxia, acidosis, and inflammation, and are associated with improved outcomes and reduced complications. DPR shows promise in patients with hemorrhagic shock, septic shock, and other conditions resulting in an open abdomen after damage control laparotomy.

High-resolution alternating magnetic force microscopy using an amorphous FeB-based tip driven by an inverse magnetostrictive effect: Imaging of the high-density magnetic recording media

The improved spatial resolution of the alternating magnetic force microscopy (A-MFM) technique developed in this work is demonstrated using a tip coated with a very thin magnetostrictive Fe-B-based amorphous film. Its magnetization can be periodically reversed using an applied alternating current magnetic field, which leads to alternating mechanical stress at the tip end, thus affecting localized magnetization reversal via an inverse magnetostrictive effect. Spatial resolution improvement is achieved via effective reversible magnetization volume at the sharpened tip end, which promotes a decrease in the total magnetic volume and maintains sufficient sensitivity at a lower coating thickness. A-MFM uses frequency modulation induced by an off-resonant alternating magnetic force between the tip and the sample. Therefore, a magnetic force can be selectively detected near the sample surface, independent of non-magnetic interactions. Due to their smooth surfaces without crystalline grain boundaries, large magnetization, and large magnetostriction compared with those of other magnetic materials, Fe-based amorphous films are suitable for tip coating applications. A 500-kfci perpendicular magnetic recording medium (PMR) was imaged using a 6-nm thick amorphous Fe-B coated tip to produce highly resolved images with minimal detection of the wavelength of the magnetic field of less than 10 nm. Also, 1600-kfci PMR imaging was successfully achieved, with the images showing individual ∼ 15-nm bits.

Contribution of Awns to Seed Yield and Seed Shattering in Siberian Wildrye Grown under Irrigated and Rainfed Environments

The seed yield of grass species is greatly dependent on inflorescence morphological traits, starting with spikelets per inflorescence and seeds per spikelet, to kernel size, and then to awns. Previous studies have attempted to estimate the contribution of these traits on the harvested yield of major cereal crops, but little information can be accessed on the influence of awns on seed yield of forage grass species. Siberian wildrye (Elymus sibiricus L.) is a widely important perennial forage grass used to increase forage production in arid and semi-arid grasslands. The grass has long inflorescences with long awns developed at the tip end of the lemmas in the florets. In order to evaluate the effect of awns on Siberian wildrye seed production, awn excision analyses from 10 accessions were performed at flowering stage under irrigated and rainfed regimes. Overall, awn excision reduced thousand-seed weight and seed size under both irrigated and rainfed regimes, which decreased final seed yield per plant. De-awned plants produced significantly more seeds per inflorescence, but spikelets per inflorescence was not influenced by awn excision in either condition. Moreover, histological analyses showed a high degradation of the abscission layer in the awned plants than de-awned ones, and awn excision evidently improved average seed breaking tensile strength (BTS), and thus decreased the degree of seed shattering. In conclusion, the observed significant impact of awn excision on different yield-related traits mirrored the impact of awns on the performance of Siberian wildrye under diverse growing conditions. These results provide useful information for plant breeders, seed producers, and researchers to efficiently improve seed production in Siberian wildrye.

Investigation of Valve Tip End Wear Mechanism of a Four-Cylinder Automotive Engine Under High-Speed Application

This work investigates the causes of wear occurring at the engine valve tip end after 400 hours of engine operation. Fatigue wear was observed on the valve tip at the product development stage of the engine, which is going to be used in an automotive vehicle. Valves were assembled on a gasoline/CNG fuel-based four-cylinder IC engine. In this engine, tip end wear was prominent during high-speed testing conditions as compared to other types of engine tests. The chemical composition of worn surfaces was verified by spectroscopy. The microstructures, grain sizes and surface roughness were determined by optical microscopy and surface roughness tester. To evaluate the wear mechanism, valve tip end worn surfaces were analyzed using Scanning electron microscopy. The SEM analysis indicates the initiation of micropits and subsequent propagation of the fatigue wear during engine operating conditions. The residual stresses were measured at valve tip end surfaces and subsurfaces using X-ray diffraction techniques. Several investigations employing multiple techniques were carried out to identify the root cause of failure while comparing results against those of untested valves. Parameters that can affect valve tip end properties were identified in the study and countermeasures provided, and that lead to successful completion of the testing with the same operating condition.

Antenna Enhanced Infrared Photoinduced Force Imaging in Aqueous Environment with Super-Resolution and Hypersensitivity

Tip enhanced IR spectra and imaging have been widely used in cutting-edge studies for the in-depth understanding of the composition, structure and function of interfaces at the nanoscale. However, molecular monolayer sensitivity has only been demonstrated on solid/gas interfaces. In aqueous environment, the reduced sensitivity due to strong damping of the cantilever oscillation and background IR absorption extremely limits the practical applications of tip enhanced IR nanospectroscopy. Here, we demonstrate hypersensitive nanoscale IR spectra and imaging in aqueous environment with the combination of photoinduced force (PiF) microscopy and resonant antennas. The highly confined electromagnetic field inbetween the tip end and antenna extremely amplifies the photoinduced force to the detectable level, while the excitation via plasmon internal reflection mode minimizes the environmental absorption. A polydimethylsiloxane (PDMS) layer (~1-2 nm thickness) functionalized on the AFM tip has been successfully identified in water with antennas of different sizes. Sampling volume of ~604 chemical bonds from PDMS was demonstrated with sub-10 nm spatial resolution confirmed by electric (E) field distribution mapping on antennas, which strongly suggests the desired requirements for interfacial spectroscopy. This platform demonstrates for the first time the application of photoinduced force microscopy in aqueous environments, providing a brand-new configuration to achieve highly enhanced nanoscale IR signals, which is extremely promising for future research of interfaces and nanosystems in aqueous environments.

Reliability Analysis of Revetments near Canti Pier, South Lampung

Canti pier is located in Southern Lampung and faces the Sunda strait water areas. Locals use this pier sailing to Sebesi island, and tourists need it as the closest starting point from the mainland to explore Krakatoa’s natural reserve. As a volcano tsunami occurred last December of 2018, Canti was one of the affected locations. Previous study shows measured wave height of 3-7 m in Way Muli and Kahai beach, located around 10 km from Canti. Field observation clearly shows the damaged concrete structure of the T-shaped Canti pier’s end tip due to the tsunami. This research focuses on analyzing the reliability of the north and south revetments of the Canti pier that still exists using statistic and probability methods. Van der Meer’s rock stability formula is adopted as the basis of determining the Limit State Function (LSF). For the reliability method, the FORM (First Order Reliability Method) is applied and produces the probability of failure of the revetment’s system during particular designed service times. The result shows that the northern revetment is relatively more robust than the southern revetment as its probability of failure is slightly lower. The expected failure probabilities are acceptable during regular operation for both revetments (less than 15%). If there is a stormy condition, the chance of collapse south revetment is relatively higher. One could also foresee the total collapse of revetments if tsunami waves attack. This condition also describes the 2018 tsunami wave height in Canti is much lower than in Way Muli since this area is sheltered by some islands, such as Sebuku and Sebesi. To conclude, considering the normal wave condition, the revetment’s structures are still reliable. However, if extreme waves occur, the revetments’ reliability is noticeably low or even unreliable (tsunami waves).

Anal Extrusion of Ventriculoperitoneal Shunt: A Case Report and Review of Literature

Ventriculoperitoneal (VP) Shunt is a commonly performed surgical procedure and offers a good result in the treatment of hydrocephalus. In general, 25% of the complication rate of this surgical procedure is abdominal complications. Anal extrusion of a peritoneal catheter is a rare complication ranging from 0.1 to 0.7% of all shunt surgeries. This study presents a rare case of anal extrusion of ventriculoperitoneal shunt in a 1-year-old female child who was asymptomatic. The physical examination revealed swelling and redness along the shunt tract on the retro auricular region, soft abdomen, and no catheter was observed in the anal. This study found several contributing factors affecting the complications in the anal extrusion of a peritoneal catheter, that are thin bowel wall in children and sharp tip and stiff end of VP shunt. The shunt should be disconnected from the abdominal wall, and the lower end should be removed through the rectum by colonoscopy or sigmoidoscopy/proctoscopy or by applying gentle traction on the protruding tube. This study concludes that due to potentially life-threatening consequences and case rarity, thorough anamnesis, physical examination, and objective investigation are needed to determine the appropriate management for anal extrusion of ventriculoperitoneal shunt.Â

Turkic burial accompanied by horses from the Upper Irtysh River region

The second half of the 1st millennium AD is associated with the development and formation of the culture of ancient Turkic peoples, who repeatedly developed several large ethnopolitical associations in the steppe zone of Central Asia. Political and cultural influences of the Turkic state formations were perceived not only by the seden-tary population of the states that existed in the territory of East and Central Asia, but also by further north peoples who lived in the steppe and taiga zones. Under the Turkic influence, or with their direct participation, the Kimako-Kipchak proto-state association began taking shape in the Upper Irtysh River region in the 7th century AD. The initial stage of this process, features of the funeral rite, and characteristic elements of the material culture of the population living in the region are almost unknown due to insufficient exploration of the monuments of the devel-opmental stage of this polyethnic formation. The paper describes the materials of the barrow cemetery of Menov-noye XII, located in the territory of the Upper Irtysh River, 2.1 km southeast of the village of Menovnoye, Tavrichesky district, East Kazakhstan Province. Under the barrow mound, there was a fence with outbuildings containing burials of a man, two horses, and two dogs. The central burial was robbed. The sacrificial pit, located north of the main grave, contained the burial of two horses, laid on their stomachs with their legs tucked under their bodies and with their heads oriented to the east. The buried person was accompanied by two dogs: one was laid across the ceiling of the grave, while the other was buried in a separate pit in an additional annex. The grave goods found with the deceased represented by astragali, a bronze ring, and a fragment of an iron arrowhead. The horse harness included stirrups and iron bits. The bridle belts were adorned with bronze items: bells, triplet plaques, bronze onlays, and belt tip ends. Bronze buckles with iron tongues, which were tucked into clips, were used to adjust the tension of the headband straps. The funeral rite features and analysis of the materials collected during the study of the memorial complex make it possible to associate the burials of the 3rd barrow of the Menov-noye XII with the Early Kimak antiquities within the framework of the Turkic era and to date them to the second half of the 7th — 8th century AD.

Multidisciplinary cooperative mode led by infusion nurse specialists used to ensure the nursing quality of peripherally inserted central catheters in China: A 5-year retrospective study.

To analyze the effect of multidisciplinary cooperation mode (MCM) led by infusion nurse specialists (INSs) on peripherally inserted central catheters (PICC) catheterization and indwelling nursing quality. Participants' demographic information, catheter types, catheterization approaches, puncture site, tip position, professional title of nurses, success rate of catheterization, consultation rate, detection rate of complications and outcome improvement rate of 6576 outpatients and hospitalized patients with PICC were analyzed retrospectively by a software named "questionnaire stars," in a large tertiary general hospital in Shanghai, from January 2015 to December 2019. SPSS 26.0 for Windows was used for data collection and description, Chi-square test were used for statistical analysis of enumeration data, and p < 0.05 was statistically significant. According to the catheter types' data, the use rate of three-way valve catheters decreased from 79.9% to 14.5%, while the use rate of three-way valve solo catheters increased from 12.7% to 51.6%, and the use rate of power injectable and open-ended catheters increased from 7.4% to 33.9%. According to the data of PICC catheterization method, conventional technology decreased significantly from 16.8% to 1.1%, modified Seldinger technique (MST) increased gradually from 26.1% to 51.3%, while ultrasound guided modified Seldinger technique (US and MST) decreased slightly from 57.2% to 47.6%. 7.5% catheter tip ends were malpositioned while nine indwelled PICCs were traced to have tip end malposition. The consultation rate was significantly higher than that before applying MCM led by INSs (x2 = 151.713, p < 0.05). After applying MCM led by INSs, the detection rate of complications was significantly higher than before (x2 = 5.499, p < 0.05), the rate of successful insertion at one time was significantly higher than before (x2 = 187.589, p < 0.05). After the application of INSs-led MCM, progresses have been achieved. The nursing quality of patients' PICC was significantly improved than before.

Epicutaneous Allergen Administration with Microneedles as a Novel Method of Immunotherapy for House Dust Mite (HDM) Allergic Rhinitis.

Epicutaneous immunotherapy (EPIT) is being studied as a method for treating allergic rhinitis because of skin immunology, user convenience and enhanced patient compliance. However, the use of EPIT is limited because of the very low skin permeability of the allergen. In this study, the limitations of EPIT were overcome by using sophisticated delivery with microneedles. The immunological efficacy of this method was studied in a murine model of house dust mite (HDM) allergic rhinitis. The length of the microneedles was 400μm, and the coating formulation containing HDM was locally distributed near the end of the microneedle tips. The change of distribution of FITC-dextran in porcine skin in vitro was observed over time using a confocal microscope. The effect of immunotherapy in the allergic rhinitis model, sensitized by HDM-coated microneedles (HDM MNs), was observed according to the amount of HDM applied. The microneedles delivered the coating formulation with precision into the porcine skin layer, and the coated formulation on the microneedles was all dissolved in the porcine skin in vitro within 20min of administration and then gradually diffused into the skin layer. When HDM MNs were administered to mice, a 0.1-μg dose of HDM provided the most effective immunization, and improved efficacy was shown between 0.1- and 0.5- μg doses of HDM. Effective immunotherapy can be achieved by precision delivery of the allergen into the skin layer, and microneedles can provide effective immunological therapy by delivering the appropriate amount of allergen.

Metal particle induced spacer surface charging phenomena in direct current gas-insulated transmission lines

The interpretation of the surface charge pattern of spacers in gas-insulated transmission lines (GIL) is a research topic with great importance, which requires a comprehensive understanding of charge behaviors at physical interfaces. Here, we report a surface charging phenomenon of spacers in the presence of metal particles inside the direct current (DC) GIL. The charging of spherical metal particles on the spacer surface appears as dotted discontinuously distributed charge spots, which are due to the charge injection from the induced charge of the metal particle and gas ionization over the metal particle surface. Concentrically distributed bipolar charge patterns are seen to build up, which are due to the surface trapping of charges from gas ionization at the end tip of the acicular metal particle. The lateral type of ionization obeys the law of dielectric barrier discharge of the needle-plate electrode in an intense DC electric field, which may bring significant influence on the safety of the spacer. The study in this letter provides direct evidence demonstrating the surface charge patterns of spacers in the presence of metal particles, which serves as an important basis for the design of DC GIL.

Plasmonic gold nanojets fabricated by a femtosecond laser irradiation.

Gold nanojets with various morphologies, from nanopillar to nanotip with up to 800 nm height, and finally to nanotip with droplet, are fabricated on gold thin film by a femtosecond laser irradiation. The near-field localized surface plasmon resonance (LSPR) and photothermal effects of gold nanojets are studied through finite element electromagnetic (EM) analysis, supporting in nanojets design for potential applications of high-resolution imaging, nanomanipulation and sensing. For an individual nanotip, the confined electron oscillations in LSPR lead to an intense local EM field up to three orders of magnitude stronger than the incident field strength at the end of gold tip, where the vertical resolution for the field enhancement was improved down to nanoscale due to the small size of the sharp gold tip (5-nm-radius). At specific wavelength, nanopillar can serve as an effective light-to-heat converter and its heating can be fine-tuned by external irradiation, and its dimension. The long-range periodic nanojet arrays (periods from 1.5 µm to 2.5 µm) with different geometry were printed using several pulse energy levels. By confining more light into the tip (two orders of magnitude stronger than single tip), nanotip array shows more pronounced potential to serve as a refractometric sensor due to their high sensitivity and reproducibility. These results promote fs laser printing as a high-precision tool for nanoarchitecture in optical imaging, nanomanipulation and sensing application.

Microhardness homogeneity of RBCs light-cured with a multiple-peak LED and surface characterization after wear.

This in vitro study evaluated the effect of the beam homogeneity of a multiple-peak light-curing unit on the surface microhardness and the effect of toothbrushing wear on the microhardness, surface roughness, roughness profile, volume loss, and gloss retention of incremental and bulk-fill resin-based composites (RBCs). A LED light-curing unit (VALO) with four LEDs at the tip end (405, 445, 465A, and 465B nm emission peak) was used according to each manufacturer-recommended time to obtain disks (n=10) of six RBCs: Estelite Sigma Quick, Charisma Classic, Tetric EvoCeram Bulk Fill, Filtek Z250, Filtek Supreme Ultra, and Filtek Bulk Fill. Microhardness values were obtained according to each LED positioning of the light-curing unit on the top surface of the RBCs and were analyzed before and after toothbrushing regarding microhardness, surface roughness, roughness profile, volume loss, and gloss retention. Microhardness was considered homogeneous on the top surface regardless of the type of RBC or wavelength tested (p>0.05). Overall, toothbrushing did not reduce the microhardness of the RBCs but influenced the gloss values for most RBCs (p<0.001). Charisma Classic presented the greatest surface roughness and roughness profile after toothbrushing (p<0.05). Volume loss did not differ among RBCs (p>0.05). In conclusion, different wavelengths of the LED did not affect the top surface microhardness, regardless of the RBCs tested; and bulk-fill composites presented similar surface changes (microhardness, surface roughness, roughness profile, volume loss, and gloss retention) when compared to conventional composites after toothbrushing.

A novel design of bioinspired retinal vascular network based microchannel for LOC applications

Microchannels are identified as important components that transfer liquids within a minute area for microfluidic applications. Pressure controlling is an efficient and most accurate way to introduce a certain velocity of equipment. In this study, we described the simulation analysis for microfluidic channels with three inlets and one outlet and went on to optimize it to two inlets and one outlet with appropriate velocity profiles and pressure profiles. The grooves in the microchannel draw inspiration from the vascular network of the retina which is a dynamically interconnected structure composed of three planar vascular layers with bends and grooves at its tip ends. Different fluids enter the inlets and are supposed to get mixed as much as possible before leaving the outlet. The geometry needs to be modified to increase the mixing of the two fluids within 0.05 sec. A passive approach to induce mixing of the biological samples is facilitated by increasing the distances. The fluids travel longer distances for mixing because of diffusive and inertial forces for which the volumetric fluids travel long before mixing takes place. The channel length is increased by introducing groove along the center of each channel to increase the length for the mixing.

Direct imaging of fluorescence enhancement in the gap between two gold nanodisks

We present an analysis of the optical coupling between two gold nanodisks by near-field fluorescence microscopy. This is achieved by simultaneously scanning and measuring the light emitted by a single Er3+/Yb3+ doped nanocrystal glued at the end of an atomic force microscope tip. The excitation of the nanocrystal was performed at λ = 975 nm via upconversion, and fluorescence was detected in the visible part of the spectrum at λ = 550 nm. For an isolated nanodisk, the near-field presents a two-lobe pattern oriented along the direction of the incident polarization. For two nanodisks with a sizable separation distance (385 nm) illuminated with the polarization along the interparticle axis, we observe a negative effect of the coupling with a slight decrease in fluorescence in the gap. For smaller gap values (195, 95, and 55 nm), a strong increase in fluorescence is observed as well as a reduced spatial localization of the field as the distance decreases. Finally, when the disks touch each other (0 nm), the dipolar–dipolar interaction between them disappears and no fluorescence enhancement occurs. A new plasmon mode is created at another wavelength. Our experimental results are in good agreement with numerical simulations of the near-field intensity distribution at the excitation wavelength on the surface of the structures. Combining fluorescence mapping and far-field scattering spectroscopy should be of strong interest to develop bio-chemical sensors based on field enhancement effects.

Localization of Major Ephedra Alkaloids in Whole Aerial Parts of Ephedrae Herba Using Direct Analysis in Real Time-Time of Flight-Mass Spectrometry.

Mass spectrometry-based molecular imaging has been utilized to map the spatial distribution of target metabolites in various matrixes. Among the diverse mass spectrometry techniques, matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) is the most popular for molecular imaging due to its powerful spatial resolution. This unparalleled high resolution, however, can paradoxically act as a bottleneck when the bio-imaging of large areas, such as a whole plant, is required. To address this issue and provide a more versatile tool for large scale bio-imaging, direct analysis in real-time-time of flight-mass spectrometry (DART-TOF-MS), an ambient ionization MS, was applied to whole plant bio-imaging of a medicinal plant, Ephedrae Herba. The whole aerial part of the plant was cut into 10–20 cm long pieces, and each part was further cut longitudinally to compare the contents of major ephedra alkaloids between the outer surface and inner part of the stem. Using optimized DART-TOF-MS conditions, molecular imaging of major ephedra alkaloids of the whole aerial part of a single plant was successfully achieved. The concentration of alkaloids analyzed in this study was found to be higher on the inner section than the outer surface of stems. Moreover, side branches, which are used in traditional medicine, represented a far higher concentration of alkaloids than the main stem. In terms of the spatial metabolic distribution, the contents of alkaloids gradually decreased towards the end of branch tips. In this study, a fast and simple macro-scale MS imaging of the whole plant was successfully developed using DART-TOF-MS. This application on the localization of secondary metabolites in whole plants can provide an area of new research using ambient ionization mass spectroscopy and an unprecedented macro-scale view of the biosynthesis and distribution of active components in medicinal plants.