STM Light Emission and I(V) study of single gold nanoantenna

Hight-speed optical nanoemitters are of importance for on-chip optical data processing. A tunnel junctions can be a base for such light emitters, however such structures suffer from low quantum efficiency. One of the ways to improve efficiency of tunneling electron energy to photon generation conversion is the increase of the local density of optical states by using of optical nanoantennas. In this work, we study optoelectronic properties of single gold nanodisc with high spatial resolution. We show nonuniform distribution of electromagnetic near-fields of nanodisk, which is consistent with nanoantenna optical modes. And we demonstrate direct correlation between nanoantenna optical states and features on current-voltage characteristics of tunnel junction between metal tip and nanodisk.

Thermal Evaluation of a Micro-Coaxial Antenna Set to Treat Bone Tumors: Design, Parametric FEM Modeling and Evaluation in Multilayer Phantom and Ex Vivo Porcine Tissue

Bone cancer is rare in adults, the most affected persons by this disease are young people and children. The common treatments for bone cancer are surgery, chemotherapy, and targeted therapies; however, all of them have side-effects that decrease the patient’s quality of life. Thermotherapy is one of the most promising treatments for bone cancer; its main goal is to increase the tumor temperature to kill cancerous cells. Although some micro-coaxial antennas have been used to treat bone tumors, most of them are designed to treat soft tissue. Therefore, the purpose of this work is to analyze the thermal behavior of four micro-coaxial antennas specifically designed to generate thermal ablation in bone tissue to treat bone tumors, at 2.45 GHz. The proposed antennas were the metal-tip monopole (MTM), the choked metal-tip monopole (CMTM), the double slot (DS) and the choked double slot (CDS). The design and optimization of the antennas by using the Finite Element Method (FEM) allow to predict the optimal antenna dimensions and their performance when they are in contact with the affected biological tissues (bone, muscle, and fat). In the FEM model, a maximum power transmission was selected as the main parameter to choose the optimum antenna design, i.e., a Standing Wave Ratio (SWR) value around 1.2–1.5. The four optimized antennas were constructed and experimentally evaluated. The evaluation was carried out in multilayer phantoms (fat, muscle, cortical, and cancellous bone) and ex vivo porcine tissue at different insertion depths of the antennas. To fully evaluate the antennas performance, the standing wave ratio (SWR), power loss, temperature profiles, and thermal distributions were analyzed. In the experimentation, the four antennas were able to reach ablation temperatures (>60 °C) and the highest reached SWR was 1.7; the MTM (power loss around 16%) and the CDS (power loss around 6.4%) antennas presented the lowest SWR values depending on the antenna insertion depth, either in multilayer tissue phantom or in ex vivo tissue. These proposed antennas allow to obtain ablation temperatures with an input power of 5 W after 5 min of treatment; these values are lower than the ones reported in the literature.

Clinical case of extensive subconjunctival rupture of the sclera with a favorable outcome

Aim. To present a clinical case of severe open injury of the eyeball of a con-tusion nature with the presence of intraocular complications and to show that de-spite the significant severity of the injury, good results can be achieved. Material and methods. Patient injured his right eye at home with a metal tip on a rubber band, after which his vision sharply decreased, pain and lacrimation of the right eye appeared. Objectively: vision of the right eye pr. l. certae, intraocular pressure (palpation) - hypotension. No foreign body was found on the survey radi-ograph of the orbits. An ultrasound B-scan revealed hemophthalmus, and subse-quently (after 7 days) retinal detachment appeared. The patient underwent vitrec-tomy, tamponade of the vitreous cavity with silicone oil, endolaser coagulation of the retina. Results. On the 1st day after the operation, the visual acuity increased to 0.4 with correction (shp +8.0). 3 months after discharge from the hospital, the patient had complete safety of the eyeball and stable functional results were achieved, where the visual functions of the injured eye were 0.5 with correction (shp + 8.0). Conclusions. A clinical case of severe open eye injury with extensive sub-conjunctival rupture of the sclera, hemophthalmos and retinal detachment demon-strates that, despite the severity of the injury, with timely provision of high-tech surgical care, there is a real chance of saving the eyeball and get high visual func-tions. Key words: Traumatic vitreous haemorrhage; vitrectomy; subconjunctival rupture of the sclera; retinal detachment.

Central Aortic Cannula Disruption Following Left Atrial Myxoma Excision

Background Central aortic cannulation is used to give oxygenated blood to the patient through a heart-lung machine. Major surgical intraoperative bleeding during cardiac surgery is a dreaded complication, resulting in significant morbidity and mortality. Central Aortic cannula disruption during Cardiopulmonary bypass (CPB) is a rare complication which needs prompt management. Case Presentation We are reporting a case of central aortic cannula disruption during LA myxoma excision in which the Metal tip part of the cannula detached from its body, resulting in massive blood loss. Intraoperative blood salvage technique was used to maintain hemodynamics during surgery.Conclusion Aortic cannula disruption is a rare complication and can be lethal to the patient, if not managed timely. Before cannulation, proper visual inspection of all cannulae by team members is very important to eliminate this type of complication.

Atomic Forces and Tunneling

This chapter presents a unified theory of tunneling phenomenon and covalent bond force, as a result of the similarity between the Bardeen theory of tunneling and the Herring-Landau theory of the covalent bond. Three general theoretical treatments are presented, which show that tunneling conductance is proportional to the square of the covalent bond interaction energy, or equivalently, the square of covalent bond force. The constant of proportionality is related to the electronic properties of the materials. For the case of a metal tip and a metal sample, an explicit equation contains only measurable physical quantities is derived. Several experimental verifications are presented. The equivalence of covalent bond energy and tunneling conductance provides a theoretical explanation of the threshold resistance observed in atom-manipulation experiments, and points to a method of predicting the threshold resistance for atom manipulation. Theory of imaging wavefunctions with AFM is discussed.

Thermic Epidermic Tissue Surgical Generator Using Bipolar Electrode

Hemostasis remains the foremost vital role of cautery, without hemostasis we have the danger of bleeding which results in the worst-case of a retro neural structure intumescence and visual impairment. Hemostasia permits for a safer and a lot of favorable outcomes, besides hemostasia cautery is used for different functions. We use it ordinarily in medicine to induce timely structure for patients with dry eyes, to shut conjunctivas incisions also as a surgical marker. Heat is generated through associate electrical current and flows to a metal tip to coagulate blood vessels to stop bleeding. Electrocautery comes within the monopolar or bipolar style with monopolar electrocautery and is applied through a hand-held active conductor which travels back to the generator through an inactive conductor connected to the patient (the grounding pad). Therefore, the patient is an element of the circuit. The inactive conductor is usually placed on the outsized space of the body to avoid physical heat phenomenon. With bipolar electrocautery, the existing is passed between one extractor tip to the opposite and a restricted quantity of tissue is cauterized in between. The existing is unfolded with monopolar electrocautery in which there's a lot of tissue harm and the tissue recovery takes a longer time.

Understanding the Role of Different Substrate Geometries for Achieving Optimum Tip-Enhanced Raman Scattering Sensitivity

Tip-enhanced Raman spectroscopy (TERS) has experienced tremendous progress over the last two decades. Despite detecting single molecules and achieving sub-nanometer spatial resolution, attaining high TERS sensitivity is still a challenging task due to low reproducibility of tip fabrication, especially regarding very sharp tip apices. Here, we present an approach for achieving strong TERS sensitivity via a systematic study of the near-field enhancement properties in the so-called gap-mode TERS configurations using the combination of finite element method (FEM) simulations and TERS experiments. In the simulation study, a gold tip apex is fixed at 80 nm of diameter, and the substrate consists of 20 nm high gold nanodiscs with diameter varying from 5 nm to 120 nm placed on a flat extended gold substrate. The local electric field distributions are computed in the spectral range from 500 nm to 800 nm with the tip placed both at the center and the edge of the gold nanostructure. The model is then compared with the typical gap-mode TERS configuration, in which a tip of varying diameter from 2 nm to 160 nm is placed in the proximity of a gold thin film. Our simulations show that the tip-nanodisc combined system provides much improved TERS sensitivity compared to the conventional gap-mode TERS configuration. We find that for the same tip diameter, the spatial resolution achieved in the tip-nanodisc model is much better than that observed in the conventional gap-mode TERS, which requires a very sharp metal tip to achieve the same spatial resolution on an extended metal substrate. Finally, TERS experiments are conducted on gold nanodisc arrays using home-built gold tips to validate our simulation results. Our simulations provide a guide for designing and realization of both high-spatial resolution and strong TERS intensity in future TERS experiments.