Use Of Cavity Research Articles

Potential of Oral Cavity Stem Cells for Bone Regeneration: A Scoping Review

Bone loss is a common problem that ranges from small defects to large defects after trauma, surgery, or congenital malformations. The oral cavity is a rich source of mesenchymal stromal cells (MSCs). Researchers have documented their isolation and studied their osteogenic potential. Therefore, the objective of this review was to analyze and compare the potential of MSCs from the oral cavity for use in bone regeneration. Methods: A scoping review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. The databases reviewed were PubMed, SCOPUS, Scientific Electronic Library Online (SciELO), and Web of Science. Studies using stem cells from the oral cavity to promote bone regeneration were included. Results: A total of 726 studies were found, of which 27 were selected. The MSCs used to repair bone defects were (I) dental pulp stem cells of permanent teeth, (II) stem cells derived from inflamed dental pulp, (III) stem cells from exfoliated deciduous teeth, (IV) periodontal ligament stem cells, (V) cultured autogenous periosteal cells, (VI) buccal fat pad-derived cells, and (VII) autologous bone-derived mesenchymal stem cells. Stem cells associate with scaffolds to facilitate insertion into the bone defect and to enhance bone regeneration. The biological risk and morbidity of the MSC-grafted site were minimal. Successful bone formation after MSC grafting has been shown for small defects with stem cells from the periodontal ligament and dental pulp as well as larger defects with stem cells from the periosteum, bone, and buccal fat pad. Conclusions: Stem cells of maxillofacial origin are a promising alternative to treat small and large craniofacial bone defects; however, an additional scaffold complement is required for stem cell delivery.

A New Two-Foci V-Trough Concentrator for Small-Scale Linear Fresnel Reflectors

We present the design of an original secondary cavity for use in Small-Scale Fresnel Reflectors in photovoltaic applications. The cavity is similar to the classical V-trough, but the primary reflector system is configured so that there are two focal points on the aperture. The rays coming from each side of the primary system reach the opposite side of the cavity, producing a non-symmetrical distribution of the irradiance. This modifies the acceptance half-angle and allows us to break the maximum limit for the concentration ratio of ideal symmetric concentrators. Our study is analytic, and we provide formulas for any number of reflections. Numerical simulations with a ray-tracing program based on MATLAB are included. We provide a comparison of optical concentration ratio, height and cost parameter between our system and two classical designs with a single focal point: the V-trough and the Compound Parabolic concentrators. This way, we verify that our design yields better concentration ratios while keeping the ray acceptance rate at one. Our solution proves to be better than both the classical one-focus V-trough and the Compound Parabolic concentrator. Specifically, the proposed solution is significantly better than the classical one-focus V-trough in optical concentration ratio, with an increase between 15.02 and 35.95%. As regards the compound parabolic concentrator, the optical concentration ratio is always slightly better (around 4%). The height of the cavity, however, is notably less in this design (around 54.33%).

Submonolayer and Monolayer Sn Adsorption and Diffusion Behavior on Oxidized Nb(100)

Current efforts to produce brighter beams of charged particles are focused on developing Nb3Sn-coated superconducting radio frequency (SRF) cavities for use in superconducting accelerator facilities. The growth mechanisms driving the formation of Nb3Sn films on preexisting Nb SRF cavities are not, however, fully understood. In order to understand the complex interplay between metallic Sn and the oxidized Nb surface leading to Nb3Sn alloy formation, we have examined how the structural and chemical composition of an oxidized Nb(100) single crystal influences Sn adsorption and diffusion behavior at submonolayer and monolayer Sn coverages. Sn was deposited on an NbO surface and annealed at temperatures relevant to Nb3Sn growth procedures before analysis via in situ scanning tunneling microscopy (STM). Experimental data, along with supporting simulated STM and calculated binding energies obtained using density functional theory, revealed the influence of Sn coverage and annealing temperatures on thermodynamic and kinetically driven diffusion pathways, preferred binding sites, novel Sn adlayer structures, and how the underlying NbO substrate evolves to accommodate Sn diffusion. This newly realized understanding of the interfacial chemical interactions between adsorbed Sn and the Nb surface sites is essential to develop predictive growth models for Nb3Sn films for use in future SRF cavities.

Modelling of semiconductor laser with double external cavities for use in ultrahigh speed photonics

Modelling of semiconductor laser with double external cavities for use in ultrahigh speed photonics

Transient heating in fixed length optical cavities for use as temperature and pressure standards

Optical refractometry techniques enable realization of both pressure and temperature directly from properties of the gas. The NIST refractometer, a fixed length optical cavity (FLOC) has previously been evaluated for operation as pressure standard, and now in this paper, is evaluated for the feasibility of operation as a primary temperature standard as well. The challenge is that during operation, one cavity is filled with gas. Gas dynamics predicts that this will result in heating which in turn will affect the cavity temperature uniformity, impeding the ability to measure the gas temperature with sufficient accuracy to make the standard useful as a primary standard for temperature or pressure. Temperature uniformity across the refractometer must be less than 0.5 mK for measurements of the refractivity to be sufficiently accurate for the FLOC. This paper compares computer modeling to laboratory measurements, enabling us to validate the model to predict thermal behavior and to accurately determine the measurement uncertainty of the technique. The results presented in this paper show that temperature of the glass elements of the refractometer and ‘thermal-shell’ copper chamber are equivalent to within 0.5 mK after an equilibration time of 3000 s (when going from 1 kPa to 100 kPa). This finding enables measurements of the copper chamber to determine the gas temperature to within an uncertainty (k = 1) of 0.5 mK. Additionally, the NIST refractometer is evaluated for feasibility of operation as temperature standard.

Hybrid drying of pulped arabica coffee cherry beans (Coffea arabica L. cv. Catuai) using a hexagonal microwave dryer designed by numerical simulations

AbstractThe consumption of specialty coffees has been increasing significantly in recent years. Their quality is influenced by several factors and the drying method is the most important. In order to reduce drying time and maintain the quality of the coffee, several techniques have been used, among which the microwave‐assisted convective drying stands out. In this work, a hexagonal microwave dryer was developed using numerical simulation techniques; then some parameters were evaluated in drying of special coffee using air at room temperature and microwaves heating, named hybrid drying. The results showed that the simulations reaches good results, being possible its use in the prediction of the electromagnetic fields and dimensioning of hexagonal cavities. In addition, the prototype performed well in the coffee drying, influenced by the coffee mass, temperature and time, reducing the moisture content from 50.4 to 10 g/100 g wet basis in 5 hr. The hybrid drying was advantageous compared with convective or microwave drying processes.Practical applicationsSpecial coffees require long drying times so that there is no loss of product quality. The application of hybrid drying by including microwave heating in the drying equipment reduces the energy cost and the processing time, providing an improvement in the processing of specialty coffees. Through this work, it was possible to verify the scale‐up potential of the microwave cavities by simulation and the hybrid drying of special coffees. The use of numerical simulation techniques for the design and scale‐up of microwave cavities will help researchers and the industry to dimension cavities for use in several scientific areas, further spreading hybrid drying via microwave.

A Tamm plasmon-porous GaN distributed Bragg reflector cavity

This paper reports on design, measurement and optimisation of a Tamm plasmon metal-distributed Bragg reflector (DBR) cavity for use in the green part of the visible spectrum. It uses an optimised silver layer thickness and a porous DBR created using a novel electro-chemical etching technique. This device has applications in low-cost lasers, photodetectors, and photoconductive switches for the visible wavelength range.

The biotechnological studies when developing lozenges with probiotics

Aim. To develop lozenges with probiotic components for the treatment and prevention of ENT diseases and analyze their effectiveness.Materials and methods. The study objects were lozenges based on xylitol and sorbitol of two compositions – based on live probiotic cultures and their metabolites. The following methods of control of the sample efficiency werechosen: determination of the number of viable lactobacilli in the study of their combined use with the drug components and the number of viable bacteria in finished oral probiotics by the Koch method (direct seeding on cups), as well as the method of diffusion into agar with the growth inhibition zone determination.Results and discussion. The studies of the properties of probiotic strains of L. fermentum 90-TC and L plantarum 8P-A3 have shown the prospects for their use in oral probiotics. It has been also proposed to use metabolitesof these strains as active components, which have a rather high antimicrobial potential to opportunistic pathogens that cause infectious ENT diseases. The oral probiotics in the form of lozenges of two compositions – based on live lactobacilli and their metabolites – have shown high efficiency, bacterial survival and antimicrobial properties, respectively.Conclusions. During the complex of the theoretical, technological and biotechnological studies, lozenges with a probiotic of two compositions (based on viable probiotic cultures and their metabolites) have been developed. After further research they can be recommended as a biologically active additive to support the oral microflora, stimulate the own immunity and as a therapeutic and prophylactic agent in infectious diseases of the oral cavity for use in both adults and children.

High-gradient behavior of a dipole-mode rf structure

A normal-conducting, X-band traveling wave structure operating in the dipole mode has been systematically high-gradient tested to gain insight into the maximum possible gradients in these types of structure. Measured structure conditioning, breakdown behavior, and achieved surface fields are reported as well as a postmortem analysis of the breakdown position and a scanning electron microscope analysis of the high-field surfaces. The results of these measurements are then compared to high-gradient results from monopole-mode cavities. Scaled to a breakdown rate of ${10}^{\ensuremath{-}6}$, the cavities were found to operate at a peak electric field of $154\text{ }\text{ }\mathrm{MV}/\mathrm{m}$ and a peak modified Poynting vector ${S}_{c}$ of $5.48\text{ }\text{ }\mathrm{MW}/{\mathrm{mm}}^{2}$. The study provides important input for the further development of dipole-mode cavities for use in the Compact Linear Collider as a crab cavity and dipole-mode cavities for use in x-ray free-electron lasers as well as for studies of the fundamental processes in vacuum arcs. Of particular relevance are the unique field patterns in dipole cavities compared to monopole cavities, where the electric and magnetic fields peak in orthogonal planes, which allow the separation of the role of electric and magnetic fields in breakdown via postmortem damage observation. The azimuthal variation of breakdown crater density is measured and is fitted to sinusoidal functions. The best fit is a power law fit of exponent 6. This is significant, as it shows how breakdown probability varies over a surface area with a varying electric field after conditioning to a given peak field.

Dynamics of bad-cavity-enhanced interaction with cold Sr atoms for laser stabilization

Hybrid systems of cold atoms and optical cavities are promising systems for increasing the stability of laser oscillators used in quantum metrology and atomic clocks. In this paper we map out the atom-cavity dynamics in such a system and demonstrate limitations as well as robustness of the approach. We investigate the phase response of an ensemble of cold strontium-88 atoms inside an optical cavity for use as an error signal in laser frequency stabilization. With this system we realize a regime where the high atomic phase-shift limits the dynamical locking range. The limitation is caused by the cavity transfer function relating input field to output field. However, the cavity dynamics is shown to have only little influence on the prospects for laser stabilization making the system robust towards cavity fluctuations and ideal for the improvement of future narrow linewidth lasers.

Dielectric Loaded High Pressure Gas Filled RF Cavities for Use in Muon Cooling Channels

Dielectric Loaded High Pressure Gas Filled RF Cavities for Use in Muon Cooling Channels

Open microwave cavity for use in a Purcell enhancement cooling scheme.

A microwave cavity is described which can be used to cool lepton plasmas for potential use in synthesis of antihydrogen. The cooling scheme is an incarnation of the Purcell effect: when plasmas are coupled to a microwave cavity, the plasma cooling rate is resonantly enhanced through increased spontaneous emission of cyclotron radiation. The cavity forms a three electrode section of a Penning-Malmberg trap and has a bulged cylindrical geometry with open ends aligned with the magnetic trapping axis. This allows plasmas to be injected and removed from the cavity without the need for moving parts while maintaining high quality factors for resonant modes. The cavity includes unique surface preparations for adjusting the cavity quality factor and achieving anti-static shielding using thin layers of nichrome and colloidal graphite, respectively. Geometric design considerations for a cavity with strong cooling power and low equilibrium plasma temperatures are discussed. Cavities of this weak-bulge design will be applicable to many situations where an open geometry is required.

Atom-Photon Coupling from Nitrogen-vacancy Centres Embedded in Tellurite Microspheres.

We have developed a technique for creating high quality tellurite microspheres with embedded nanodiamonds (NDs) containing nitrogen-vacancy (NV) centres. This hybrid method allows fluorescence of the NVs in the NDs to be directly, rather than evanescently, coupled to the whispering gallery modes of the tellurite microspheres at room temperature. As a demonstration of its sensing potential, shifting of the resonance peaks is also demonstrated by coating a sphere surface with a liquid layer. This new approach is a robust way of creating cavities for use in quantum and sensing applications.

PressurizedH2rf Cavities in Ionizing Beams and Magnetic Fields

A major technological challenge in building a muon cooling channel is operating rf cavities in multitesla external magnetic fields. We report the first proof-of-principle experiment of a high pressure gas-filled rf cavity for use with intense ionizing beams and strong external magnetic fields. rf power consumption by beam-induced plasma is investigated with hydrogen and deuterium gases with pressures between 20 and 100 atm and peak rf gradients between 5 and 50 MV/m. The low pressure case agrees well with an analytical model based on electron and ion mobilities. Varying concentrations of oxygen gas are investigated to remove free electrons from the cavity and reduce the rf power consumption. Measurements of the electron attachment time to oxygen and rate of ion-ion recombination are also made. Additionally, we demonstrate the operation of the gas-filled rf cavity in a solenoidal field of up to 3 T, finding no major magnetic field dependence. All these results indicate that a high pressure gas-filled cavity is a viable technology for muon ionization cooling.

Remote coupling between a probe and a superconducting klystron cavity for use in gravitational wave detectors

In this work the main task was to measure the remote coupling between a probe and some niobium superconducting reentrant cavities for use in parametric transducers of gravitational wave detectors. The cavities were manufactured from RRR300 niobium and cryogenically tested to determine the electromagnetic coupling among other parameters. These cavities were also closed using a RRR300 niobium cover forming a narrow axial gap with the post top. A hole was made at the base opposite the cover in order to the probe reach the cavity. Generally, the critical coupling (β ≈ 1) is achieved with the probe inside the cavity. The mechanical connection of the probe with the transducer and the external circuit introduces an unwanted seismic noise in the transducer. The microstrip antennas have been traditionally employed to make a wireless connection. However, this study has demonstrated coupling factor β ≈ 1 with the probe moved away 4.0 mm from the cavity with a 3.0 mm diameter hole. Couplings with the probe moved away 1.0 mm and 7.0 mm from cavities with 1.5 mm and 3.5 mm diameter holes, respectively, have also been obtained. These results have revealed the influence of the hole diameter with the remote coupling between an electric field probe and the klystron mode of a superconducting reentrant cavity. Due to the practicalities, this effect may replace the microstrip antennas making it possible to implement high sensitivity parametric transducers.

Short-cavity multimode fiber-tip Fabry-Pérot sensors

We make the case for minimizing cavity length of extrinsic Fabry-Pérot (FP) cavities for use in fiber-tip sensors. Doing so mitigates multiple challenges that arise from using multimode fibers: mode averaging, phase uncertainty, amplitude reduction, and spectral modal noise. We explore these effects in detail using modal simulations, and construct pressure sensors based on this principle. We discuss the multimodal effects that we observe in our fiber sensors, and use simple filtering of the spectral signal to more easily measure pressure sensitivity. The concept of short-cavity FP interferometry is important for ensuring high quality and performance of multimode fiber sensors.

Resonant microwave cavity for 8.5–12 GHz optically detected electron spin resonance with simultaneous nuclear magnetic resonance

We present a newly developed microwave resonant cavity for use in optically detected magnetic resonance (ODMR) experiments. The cylindrical quasi-TE(011) mode cavity is designed to fit in a 1 in. magnet bore to allow the sample to be optically accessed and to have an adjustable resonant frequency between 8.5 and 12 GHz. The cavity uses cylinders of high dielectric material, so-called "dielectric resonators," in a double-stacked configuration to determine the resonant frequency. Wires in a pseudo-Helmholtz configuration are incorporated into the cavity to provide frequencies for simultaneous nuclear magnetic resonance (NMR). The system was tested by measuring cavity absorption as microwave frequencies were swept, by performing ODMR on a zinc-doped InP sample, and by performing optically detected NMR on a GaAs sample. The results confirm the suitability of the cavity for ODMR with simultaneous NMR.

Robot-assisted laparoscopic presacral neurectomy: proper technique and outcomes

OBJECTIVE: To report the feasibility, description of technique, and operative outcomes of robot-assisted laparoscopic presacral neurectomy.DESIGN: Prospective case series of 17 patients with central pelvic pain and history of endometriosis who underwent robot-assisted laparoscopic presacral neurectomy from July 2006 to April 2008.MATERIALS AND METHODS: With the patient under general endotracheal anesthesia, a 12 mm intra-umbilical cannula and two 8 mm lateral ports were introduced into the peritoneal cavity for use of the da Vinci® system. The patient was placed in steep Trendelenberg position and tilted to the left. Due to the cephalad position of the interiliac triangle, as well as unique docking of the surgical cart of the da Vinci® system, the lateral ports were placed 1-2 cm above the anterior superior iliac spine for introduction of fenestrated Maryland bipolar Endowrist™ or Endowrist™ Precise™ bipolar on the left side and monopolar Hot Shears™ on the right. An additional 5 mm port was placed suprapubically for introduction of suction-irrigator, grasping forceps and tissue extraction. Triangle of Cotte anatomical landmarks were identified. The posterior peritoneum was incised at the sacral promontory. The interiliac trianle was stripped of aereolar and lymphatic tissue with exposure and excision of the superior hypogastric nervous plexus.RESULTS: Patients mean age, gravidy, and parity were 27.6, 0.5, and 0.2, respectively. Approximate mean duration of the procedure was less than 10 minutes. Mean estimated blood loss for the entire procedure was less than 30cc. Presence of nerve ganglion and fibers was confirmed by pathology in all 17 cases. At the time of analysis, follow-up ranged from 2 to 16 months. No short-term or long-term complications related to the surgical procedure were reported. All patients reported improvement of pelvic pain.CONCLUSIONS: Ergonomics of computer enhanced remote surgery create the intuitive invironment similar to laparotomy. The surgical robot provides wide angle and 3-D vision, supplemented with magnification. Bimanual manipulation of multifunctional devices and downscaled motion is tremorless. With the help of robotic technology, laparoscopic presacral neurectomy is feasible and can help the surgeon to overcome intrinsic limitations of laparoscopy and avoid modifications, which result invariably in suboptimal outcomes, thereby bridging the gap between laparotomy and laparoscopy. OBJECTIVE: To report the feasibility, description of technique, and operative outcomes of robot-assisted laparoscopic presacral neurectomy. DESIGN: Prospective case series of 17 patients with central pelvic pain and history of endometriosis who underwent robot-assisted laparoscopic presacral neurectomy from July 2006 to April 2008. MATERIALS AND METHODS: With the patient under general endotracheal anesthesia, a 12 mm intra-umbilical cannula and two 8 mm lateral ports were introduced into the peritoneal cavity for use of the da Vinci® system. The patient was placed in steep Trendelenberg position and tilted to the left. Due to the cephalad position of the interiliac triangle, as well as unique docking of the surgical cart of the da Vinci® system, the lateral ports were placed 1-2 cm above the anterior superior iliac spine for introduction of fenestrated Maryland bipolar Endowrist™ or Endowrist™ Precise™ bipolar on the left side and monopolar Hot Shears™ on the right. An additional 5 mm port was placed suprapubically for introduction of suction-irrigator, grasping forceps and tissue extraction. Triangle of Cotte anatomical landmarks were identified. The posterior peritoneum was incised at the sacral promontory. The interiliac trianle was stripped of aereolar and lymphatic tissue with exposure and excision of the superior hypogastric nervous plexus. RESULTS: Patients mean age, gravidy, and parity were 27.6, 0.5, and 0.2, respectively. Approximate mean duration of the procedure was less than 10 minutes. Mean estimated blood loss for the entire procedure was less than 30cc. Presence of nerve ganglion and fibers was confirmed by pathology in all 17 cases. At the time of analysis, follow-up ranged from 2 to 16 months. No short-term or long-term complications related to the surgical procedure were reported. All patients reported improvement of pelvic pain. CONCLUSIONS: Ergonomics of computer enhanced remote surgery create the intuitive invironment similar to laparotomy. The surgical robot provides wide angle and 3-D vision, supplemented with magnification. Bimanual manipulation of multifunctional devices and downscaled motion is tremorless. With the help of robotic technology, laparoscopic presacral neurectomy is feasible and can help the surgeon to overcome intrinsic limitations of laparoscopy and avoid modifications, which result invariably in suboptimal outcomes, thereby bridging the gap between laparotomy and laparoscopy.

Processing strategies for niobium sheet used in advanced superconducting particle accelerator cavities

Ultra-high-purity niobium sheet is used to fabricate radio frequency cavities for use in future linear accelerators. The complexity of the shapes requires the electron-beam welding of deep-drawn components, but difficulties with inconsistent formability, springback, and surface roughness have been traced to non-uniform microstructures and texture gradients that are common in commercial niobium sheet. Two approaches under study to overcome these problems are the development of fine-grained favorably textured polycrystalline sheet, and the use of a properly oriented and nearly single-crystal sheet to form pieces of the cavity. Both approaches show promise but need further work.

Nest cavity availability and selection in aspen–conifer groves in a grassland landscape

Cavity-nesting vertebrates, a significant component of forest wildlife communities, are connected ecologically in nest webs arranged in guilds of cavity producers (strong and weak excavators) and cavity consumers. The availability of tree cavities for nesting and roosting is considered critical to maintaining communities of cavity nesters. Using univariate tests and resource selection indices, we examined nesting use of both natural and excavated cavities in small aspen–conifer groves of interior British Columbia in relation to availability of cavity, tree, and habitat features. In a 2-year study, we monitored 197 cavities for use, 8% of which were lost between years. Of those that survived, 26% were occupied in both years, 29% were used in only one year, and 45% were not used in either year. Occupied cavities were larger internally than those not occupied in either year and were more likely to be in trees with only one cavity. In species-level resource selection analyses, tree swallows (Tachycineta bicolor Vieillot), European starlings (Sturnus vulgaris L.), and chickadees (Poecile spp.) used live, heart rot infected trees more than expected from their proportional abundance and used dead trees less than expected, while northern flickers (Colaptes auratus L.), mountain bluebirds (Sialia currucoides Bechstein), and red squirrels (Tamiasciurus hudsonicus Erxleben) used live and dead trees in proportion to their availability. Managed, open landscapes with small mixed or deciduous forest groves can sustain healthy communities of cavity nesters, if there is a range of suitable trees for excavators and open areas for foraging.