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Fatemeh Tara,1 Asieh Maleki,2 Nayereh Taheri,2 Somayeh Moein Darbari21Nursing and Midwifery Care Research Center, Mashhad University of Medical Sciences, Mashhad, Iran; 2Department of Obstetrics and Gynecology, Mashhad University of Medical Sciences, Mashhad, IranAbstract: One of the most common causes of fetal anemia is red cell alloimmunization. The standard treatment in fetuses with anemia is intrauterine transfusion (IUT); but this approach may have adverse effects, or sometimes it is not available or even possible. Therefore, immune modulating approaches such as therapeutic plasma exchange (TPE) and the use of intravenous immunoglobulin should be implemented to avoid or delay IUT. We report here the successful management of a case of D alloimmunization in pregnancy solely with TPE, without the need for IUT. The patient was a 33-year-old G4, L2, and D1, who had a history of alloimmunization in her previous pregnancy. TPE was initiated at 17 weeks gestation and was repeated weekly. Altogether, 20 times of plasma exchange were performed and a normal fetus was delivered at week 37.Keywords: alloimmunization, therapeutic plasma exchange, hemolytic disease of the newborn

We present the design and numerical investigation of a reconfigurable and miniature locally resonant surface acoustic wave demultiplexer based on a ZnO pillar phononic crystal, for the first time. Hollow cylinder line defects are used as waveguides, due to their good structural controllability over the local resonant waveguiding frequency and bandwidth. Two local resonant surface acoustic waveguides are designed and simulated as the output channels of the demultiplexer, and the shear-horizontal wave transmission spectra are calculated for each channel individually. The designed radio frequency demultiplexing output channels support frequencies of 4.14 GHz and 4.28 GHz, with respective bandwidths of 40 MHz and 60 MHz, while their spatial separation is just about 800 nm. In order to achieve a reconfigurable output characteristic, the effect of acoustoelectric interaction in piezoelectric semiconductors is numerically simulated in this study. The acoustoelectric interaction causes an additional stiffness in ZnO that can be released by adding extra charge carriers, i.e., increasing conductivity, thus changing the effective elasticity of the ZnO structures and the guiding frequencies of the output channels. Two output frequencies show red shifts of about 100 MHz and 150 MHz by extremely increasing the conductivity of ZnO structures from 0.01 S/m to 100 S/m. [ABSTRACT FROM AUTHOR]

Here, the response of localized surface plasmon resonance (LSPR) gas sensor has been investigated, which consists of Ag nanoparticles on glass. Output characteristic of the proposed LSPR gas sensor are investigated by exposure of different concentrations of N2 to the structure (0-250 ppm). Ag nanoparticles are synthesized chemical method, which has been optimized in order to achieve the best detection sensitivity in the output behaviour of the sensor. It is shown that the best output response is achieved for Ag nanoparticles with the diameter of about 30 nm and LSPR peak at wavelength of about 415 nm. Physical adsorption of N2 molecules on Ag nanoparticles increases the refractive index of the enclosing environment, and leads to a red-shift in the wavelength of localized surface plasmons. It is illustrated here that the shift of the LSPR spectrum is sensitive to the concentration of exposed nitrogen, with a sensitivity of about 0.56 nm versus gas concentration variation of about 100 ppm. Our experimental investigations are in agreement with the simulation results, relating to the similar structure. [ABSTRACT FROM AUTHOR]

In this paper, we investigate the curvature effects on the electronic band structure and dielectric function of singlewalled silicon nanotubes and carbon nanotubes, based on tightbinding method. The curvature nature of nanotubes causes radius-dependent s-p-orbital hybridization which leads to optimization of tight-binding model for each radii. First, the effects of orbitals overlap and the structural optimization on the electronic band structure of small radius nanotubes are investigated. Second, the imaginary part of dielectric function of nanotubes, which is related to optical absorption coefficient, is obtained by calculating the interband optical matrix elements using gradient approximation. It is shown that the s-p-tightbinding model optimization due to the curvature effects, introduces small changes to the optical transition energies obtained by simple p-band tight-binding model. The results show that the curvature effects are more important in small radius tubes. [ABSTRACT FROM AUTHOR]

The formation of high sensitivity–wide dynamic range field emission pressure sensors based on carbon nanotubes (CNTs) is reported. In this work, CNTs are grown inside an array of micromachined holes in order to ensure a high sensitivity and a wide dynamic range by allowing anode–cathode proximity while preventing anode–cathode direct contact simultaneously. External pressure is applied to a Si-based flexible anode, which results in consequent variations in emission current, due to electric field changes. Microcavities in this structure have been formed by a Si deep vertical etching process, while the CNTs have been grown by direct current plasma-enhanced chemical vapour deposition. Also, it is demonstrated that a similar fabrication process can be applied to implement a device with an electrically controllable emission current. A high sensitivity of 1.5–13.7 µA kPa−1 (with Vanode/cathode < 100 V) within a dynamic range from around 0.1 to 1 GPa, is measured in this experiment. [ABSTRACT FROM AUTHOR]

Introduction: Primary spinal glioblastoma (GBM) are very rare tumors of the spinal cord, with dismal prognosis and their exact management is controversial. We attempt to formulate treatment guidelines for these extremely rare tumors based on our institutional experience and a comprehensive review of the literature., Materials and Methods: In this retrospective study from 2008 to 2020, all the patients diagnosed with primary spinal GBM who underwent surgery at our institution were included. Clinical data were retrieved from case files, outpatient records and telephonic follow-up. Data on postoperative chemoradiation was noted in all the patients. The final diagnosis of spinal GBM was confirmed as per the histopathology reports. Patients who could not be followed up and those with prior history of cranial GBM were excluded from the study., Results: Nine patients were followed up and a median survival of 11 months was noted. Chemotherapy with TMZ and radiotherapy to the whole craniospinal axis significantly improved survival in these patients. The extent of surgical resection was not shown to be significant. Intracranial metastasis was the leading cause of mortality in such patients. Three patients developed documented intracranial metastasis during the course of the disease., Conclusions: Low threshold must be kept in mind in diagnosing patients with high-grade spinal cord intramedullary tumors in view of the rapidly progressing nature of the disease. In case of positive histopathological diagnosis of spinal GBM, the whole craniospinal axis should be imaged and any cranial metastasis which was originally missed during initial workup could be given appropriate radiotherapy.

The ever-increasing demand for high-speed data communication has fueled the development of ultra-fast electro-optic modulators. Our proposed equalizer configuration in lithium niobate on insulator electro-optic (LNOI-EO) modulators offers a novel approach to the bandwidth-voltage trade-off. Using 3D simulations, we achieved an ultra-high bandwidth of 300 GHz, delivering more than three times enhancement compared to the conventional modulators with the same base modulator length and half-wave voltage of 4.4 V. The device design incorporates a crossing segment to ensure distortion-free modulated signals and a dual-layered electrode design to minimize interference. These modulators have excellent potential for future photonic integrated circuits, marking a new era of superior bandwidth-voltage trade-offs.

Lead halide perovskites have emerged as platforms for exciton-polaritonic studies at room temperature, thanks to their excellent photoluminescence efficiency and synthetic versatility. In this work, we find proof of strong exciton-photon coupling in cavities formed by the layered crystals themselves, a phenomenon known as the self-hybridization effect. We use multilayers of high-quality Ruddlesden-Popper perovskites in their 2D crystalline form, benefiting from their quantum-well excitonic resonances and the strong Fabry-Pérot cavity modes resulting from the total internal reflection at their smooth surfaces. Optical spectroscopy reveals bending of the cavity modes typical for exciton-polariton formation, and absorption and photoluminescence spectroscopy shows splitting of the excitonic resonance and thickness-dependent peak positions. Strikingly, local optical excitation with energy below the excitonic resonance of the flakes in photoluminescence measurements unveils the coupling of light to in-plane polaritonic modes with directed propagation. These exciton-polaritons exhibit high coupling efficiencies and extremely low loss propagation mechanisms, which are confirmed by finite difference time domain simulations. Thus, we prove that mesoscopic 2D Ruddlesden-Popper perovskite flakes represent an effective but simple system to study the rich physics of exciton-polaritons at room temperature., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)

Here, we achieved pinhole-free 2D Ruddlesden-Popper Perovskite (RPP) BA 2 PbI 4 layers with close packed crystalline grains with dimension of about 30 × 30 µm 2 , which have been demonstrated to be favorable for optoelectronic applications, such as fast response RPP-based metal/semiconductor/metal photodetectors. We explored affecting parameters in hot casting of BA 2 PbI 4 layers, and proved that oxygen plasma treatment prior to hot casting plays a significant role to achieve high quality close packed polycrystalline RPP layers at lower hot cast temperatures. Moreover, we demonstrate that crystal growth of 2D BA 2 PbI 4 can be dominantly controlled by the rate of solvent evaporation through substrate temperature or rotational speed, while molarity of the prepared RPP/DMF precursor is the dominant factor that determines the RPP layer thickness, and can affect the spectral response of the realized photodetector. Benefiting from the high light absorption and inherent chemical stability of 2D RPP layers, we achieved high responsivity and stability, and fast response photodetection from perovskite active layer. We achieved a fast photoresponse with rise and fall times of 189 µs and 300 µs, and the maximum responsivity of 119 mA/W and detectivity of 2.15 × 10 8 Jones in response to illumination wavelength of 450 nm. The presented polycrystalline RPP-based photodetector benefits from a simple and low-cost fabrication process, suitable for large area production on glass substrate, a good stability and responsivity, and a promising fast photoresponse, even around that of exfoliated single crystal RPP-based counterparts. However, it is well known that exfoliation methods suffer from poor repeatability and scalability, which make them incompatible with mass production and large area applications., (© 2023. The Author(s).)

Here, we numerically prove that light with linear polarization can be coupled to surface plasmon polaritons at an elliptical hole perforated in a gold layer to generate plasmonic vortex (PV). Benefiting from the smooth variation of the minor to major ellipse axes, a gradual variation in the phase profile of the generated PV is achieved. Regarding this, three types of independent arrays of elliptical holes are presented, which can produce uniform and high quality PVs with different topological charges at the center of the arrays. The first array can produce PV with topological charges of + 1 and - 1, depending on the polarization orientation of the incident light. In the second one, the topological charge of the PV can be switched between 0 and + 2, by switching the polarization direction of the incident light. In the third array, a robust PV with topological charge of + 1 is generated independent of possible tolerances in the polarization orientation. In order to use the generated PVs for plasmonic tweezing application, there are side fringes around the central vortex of the arrays that should be eliminated. To produce a single vortex, we propose metal-insulator-metal (MIM) structures, screening excessive fringes and allowing the central PVs to leak out. It is also demonstrated by simulation that target particles, such as gold and polystyrene spheres of subwavelength dimensions, can be efficiently manipulated by our MIM designs, suitable for different applications including local mixing, and applying switchable torque or force to target particles to explore their complete elastic characteristics., (© 2023. The Author(s).)

Craniopagus conjoined twins are extremely rare, reported 1 in 2.5 million live births. To date, 62 separation attempts in 69 well-documented cases of craniopagus twins have been made. Of these, 34 were performed in a single-stage approach, and 28 were attempted in a multistage approach. One or both twins died of massive intraoperative blood loss and cardiac arrest in 14 cases. We report our surgical experience with conjoined craniopagus twins (JB) with type III total vertical joining and shared circumferential/circular sinus with left-sided dominance. A brief review of the literature is also provided. In our twins, the meticulous preoperative study and planning by the multidisciplinary team consisting of 125-member, first-staged surgical separation consisted of creation of venous conduit to bypass part of shared circumferential sinus and partial hemispheric disconnection. Six weeks later, twin J manifested acute cardiac overload because of one-way fistula development from blocked venous bypass graft necessitating emergency final separation surgery. Unique perioperative issues were abnormal anatomy, hemodynamic sequelae from one-way fistula development after venous bypass graft thrombosis, cardiac arrest after massive venous air embolism requiring prolonged cardiopulmonary resuscitation, and return of spontaneous circulation at 15 minutes immediately after separation. This is the first Indian craniopagus separation surgery in a complex total vertical craniopagus twin reported by a single-center multidisciplinary team. Both twins could be sent home, but one remained severely handicapped. Adequate perioperative planning and multidisciplinary team approach are vital in craniopagus twin separation surgeries., (Copyright © Congress of Neurological Surgeons 2022. All rights reserved.)

Surface plasmons in graphene have mainly been affected by intrinsic optical phonons due to the vibrations of the carbon atoms and surface polar optical phonons (S-POPs) of the underlying dielectric surface. This plasmon hybridization dramatically changes the features of the plasmonic devices. However, a complete theoretical model for the graphene impedance to consider the optical phonons effects is yet remained to be developed. Here, we show how to derive a model for graphene impedance to include such impacts on graphene surface plasmons. Earlier models suffer from two limitations-i.e., the inability to show (i) the transformation of a single pure plasmonic mode into multiple hybrid plasmon-phonon excitations and (ii) the damping effect for energies beyond that of the intrinsic optical phonons due to the phonon emission. Our new model overcomes these two limitations. Then, we calculate the extinction spectra for a one-dimensional periodic array of graphene ribbons obtained through the impedance boundary condition method, addressing these obstacles. These spectra are directly related to graphene impedance, modeled using the dielectric function we developed in our earlier work. The extinction spectra show the presented model overcoming the limitations, firmly fitting the experimental data reported by others. Furthermore, we introduce our developed model for graphene to the CST Studio software to verify the accuracy of our extinction relation and impedance model. This study can be a step forward correctly predicting the behavior of graphene-based plasmonic devices., (© 2022. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

The presence of species other than the target biomolecules in the fluidic analyte used in the refractive index biosensor based on the surface plasmon resonances (SPRs) can lead to measurement ambiguity. Using graphene-based acousto-plasmonic biosensors, we propose two methods to eliminate any possible ambiguity in interpreting the measured results. First, we take advantage of the dynamic tunability of graphene SPRs in the acousto-plasmonic biosensor with a surface acoustic wave (SAW) induced uniform grating, performing measurements at different applied voltages. Second, a single measurement employing a similar biosensor but with SAW-induced dual-segment gratings. The numerical results show the capability of both methods in decoupling the effect of the target analyte from the other species in the fluid, enabling interpreting the measurement results with no ambiguity. We also report the results of our numerical investigation on the effect of measuring parameters like the target layer effective refractive index and thickness, and the fluid effective refractive index, in addition to the controlling parameters of the proposed acousto-plasmonic biosensor, including graphene Fermi energy and electrical signaling on the sensing characteristics. Both types of proposed biosensors show promising features for developing the next generation lab-on-a-chip biosensors with minimal cross-sensitivities to non-target biomolecules.

In this report, a graphene-based plasmonic lens is designed for far-field position-tunable trapping of dielectric particles at a wavelength of 1550 nm, in which target particles can be floated at a variable z-position, using a variable gate voltage applied to the graphene ribbons. Preventing proximity of the trapped particle and the metallic lens structure, we can diminish general thermal issues in plasmonic tweezers, while realizing higher degrees of freedom in studying target characteristics of the particles by achieving position-tunable 3D trapping. These advantageous aspects are impossible in conventional plasmonic tweezers, because of the highly evanescent nature of the plasmonic field at the metal interface. The proposed structure is comprised of two concentric circular slit-sets (S 1 , S 2 ), each capable of sending a directive beam, which can lead to a constructive interference, and forming a subwavelength focal spot in the far-field. Taking advantage of the epsilon-near-zero (ENZ) behavior of graphene, each of the radiating slit-sets can be switched ON/OFF, with a radiation switching ratio of about 49, by applying a small electric pulse of 80 meV to change the Fermi energy of the corresponding graphene ribbon from 0.535 eV to 0.615 eV. Hence, inverting the radiation state of the designed lens, from (S 1 :ON, S 2 :OFF) to (S 1 :OFF, S 2 :ON), we can change the z-position of the focal trapping site from 5000 nm to 9800 nm. This configuration can be proposed as a new generation of long-range, electrostatically tunable 3D plasmonic tweezing, without the need for any external bulky optomechanical equipment.

In this report, we propose the closed pack array of gold discs on glass, as a dual mode plasmonic tweezers that benefits from two trapping modes. The first trapping mode is based on leaky surface plasmon mode (LSPM) on the gold discs with a longer penetration depth in the water and a longer spatial trapping range, so that target nanoparticles with a radius of 100 nm can be attracted toward the gold surface from a vertical distance of about 2 µm. This trapping mode can help to overcome the inherent short range trapping challenge in the plasmonic tweezers. The second trapping mode is based on the dimer surface plasmonic mode (DSPM) in the nano-slits between the neighboring gold discs, leading to isolated and strong trapping sites for nanoparticles smaller than 34 nm. The proposed plasmonic tweezers can be excited in both LSPM and DSPM modes by switching the incident wavelength, resulting in promising and complementary functionalities. In the proposed plasmonic tweezers, we can attract the target particles towards the gold surface by LSPM gradient force, and trap them within a wide half width half maximum (HWHM) that allows studying the interactions between the trapped particles, due to their spatial proximity. Then, by switching to the DSPM trapping mode, we can rearrange the particles in a periodic pattern of isolated and stiff traps. The proposed plasmonic structure and the presented study opens a new insight for realizing efficient, dual-mode tweezers with complementary characteristics, suitable for manipulation of nanoparticles. Our thermal simulations demonstrate that the thermal-induced forces does not interefe with the proposed plasmonic tweezing., (© 2021. The Author(s).)

Taking advantage of highly confined evanescent fields to overcome the free-space diffraction limit, we show plasmonic tweezers enable efficient trapping and manipulation of nanometric particles by low optical powers. In typical plasmonic tweezers, trapping/releasing particles is carried out by turning the laser power on and off, which cannot be achieved quickly and repeatedly during the experiment. We introduce hybrid gold-graphene plasmonic tweezers in which the trap stiffness is varied electrostatically by applying suitable voltages to a graphene layer. We show how the graphene layer absorbs the plasmonic field around the gold nanostructures in particular chemical potentials, allowing us to modulate the plasmonic force components and the trapping potential. We show graphene monolayer (bilayer) with excellent thermal properties enables more efficient heat transfer throughout the plasmonic tweezers, reducing the magnitude of thermophoretic force by about 23 (36) times. This thermophoresis suppression eliminates the risk of photothermal damage to the target sample. Our proposed plasmonic tweezers open up possibilities to develop tunable plasmonic tweezers with high-speed and versatile force-switching functionality and more efficient thermal performance.