PET Track Research Articles

Single-Cell PET Imaging and Tracking.

Positron emission tomography (PET) is one of the most sensitive whole-body molecular imaging techniques available in the clinic, able to detect picomolar levels of probe. As such, it was recently demonstrated that PET could also be used to track single radiolabeled cells in small animals. In this protocol, we present detailed procedures for radiolabeling cells using mesoporous silica nanoparticles (MSNs) and for tracking these cells in real time using in vivo PET. This includes static imaging of single cells as well as dynamic tracking of moving cells directly from the list-mode data. The protocol provides detailed instructions and examples for each step.

Enabling secure lightweight mobile Narrowband Internet of Things (NB-IoT) applications using blockchain

Narrowband Internet of Things (NB-IoT) is a low bandwidth 3GPP communication standard transmitting small quantities of data over long distances at random intervals. However, as NB-IoT cannot support seamless handover between base stations, its applications are limited to stationary devices, which may result in the potential risk of fake base station connections in an attempt to maintain connectivity across cells. Considering characteristics such as low power consumption and high connection density, researchers envision using NB-IoT in mobile applications such as public-bike sharing, pet tracking etc. Connecting NB-IoT devices using decentralised architecture such as blockchain ensures seamless communication in mobile applications and eliminates bottlenecks due to multiple data requests observed in centralised networks. In this paper, we develop a hybrid blockchain framework facilitating mutual authentication between base stations to enhance user privacy and prevent fake base station connections and certificate transfers. Zero-knowledge proof used as the consensus algorithm enhances user privacy and message confidentiality. IoT devices are designed to store the hashes of their approved transactions as a linear hash chain instead of the complete merkle tree to minimise hash verification complexity. Additionally, base station memory is partitioned dynamically to enhance scalability and memory utilisation efficiency. We prototype our framework on Remix IDE in Ethereum and implement it on Raspberry Pi 4. The security of the proposed framework is formally verified using Scyther. Further, we show that our approach achieves 80.50% lower computational power, 74.73% lower execution time and 50% lower memory, respectively, in comparison with existing schemes making our proposed scheme lightweight.

The First-in-Human Whole-Body Dynamic Pharmacokinetics Study of Aptamer.

Serving as targeting ligands, aptamers have shown promise in precision medicine. However, the lack of knowledge of the biosafety and metabolism patterns in the human body largely impeded aptamers' clinical translation. To bridge this gap, here we report the first-in-human pharmacokinetics study of protein tyrosine kinase 7 targeted SGC8 aptamer via invivo PET tracking of gallium-68 (68Ga) radiolabeled aptamers. The specificity and binding affinity of a radiolabeled aptamer, named 68Ga[Ga]-NOTA-SGC8, were maintained as proven invitro. Further preclinical biosafety and biodistribution evaluation confirmed that aptamers have no biotoxicity, potential mutation risks, or genotoxicity at high dosage (40 mg/kg). Based on this result, a first-in-human clinical trial was approved and carried out to evaluate the circulation and metabolism profiles, as well as biosafety, of the radiolabeled SGC8 aptamer in the human body. Taking advantage of the cutting-edge total-body PET, the aptamers' distribution pattern in the human body was acquired in a dynamic fashion. This study revealed that radiolabeled aptamers are harmless to normal organs and most of them are accumulated in the kidney and cleared from the bladder via urine, which agrees with preclinical studies. Meanwhile, a physiologically based pharmacokinetic model of aptamer was developed, which could potentially predict therapeutic responses and plan personalized treatment strategies. This research studied the biosafety and dynamic pharmacokinetics of aptamers in the human body for the first time, as well as demonstrated the capability of novel molecular imaging fashion in drug development.

Localization Algorithm for 3D Sensor Networks: A Recursive Data Fusion Approach.

Location-based applications for security and assisted living, such as human location tracking, pet tracking and others, have increased considerably in the last few years, enabled by the fast growth of sensor networks. Sensor location information is essential for several network protocols and applications such as routing and energy harvesting, among others. Therefore, there is a need for developing new alternative localization algorithms suitable for rough, changing environments. In this paper, we formulate the Recursive Localization (RL) algorithm, based on the recursive coordinate data fusion using at least three anchor nodes (ANs), combined with a multiplane location estimation, suitable for 3D ad hoc environments. The novelty of the proposed algorithm is the recursive fusion technique to obtain a reliable location estimation of a node by combining noisy information from several nodes. The feasibility of the RL algorithm under several network environments was examined through analytic formulation and simulation processes. The proposed algorithm improved the location accuracy for all the scenarios analyzed. Comparing with other 3D range-based positioning algorithms, we observe that the proposed RL algorithm presents several advantages, such as a smaller number of required ANs and a better position accuracy for the worst cases analyzed. On the other hand, compared to other 3D range-free positioning algorithms, we can see an improvement by around 15.6% in terms of positioning accuracy.

Thermo-activation spectroscopy of track-etched membranes based on polyethylene terephthalate films irradiated by swift Xe ions

In this work, thermally stimulated spectroscopy methods are applied to PET films to analyse the electret state. The thermally stimulated discharge currents, or thermally stimulated depolarization of track-etched like membrane samples obtained at different technological stages of their manufacture, have been investigated. The analysis of thermally stimulated depolarization currents indicates a significant change in the spectra of energy states of the electric charge accumulated during PET films' polarization after irradiation with accelerated swift Xe ions, ultraviolet treatment, and alkaline etching of the latent tracks. The Eyring method was used to calculate the parameters of the relaxation processes occurring in irradiated PET, such as the activation energy and the effective frequency factor. The significant change in the spectra of energy states of the electric charge accumulated during polarization in PET films due to ion-track processes indicates the possibility of creating an electret state in irradiated PET films and track membranes.

Geofencing technology implementation for pet tracker using Arduino based on Android

The risk of losing pets, especially pets without a leash, usually occurs because animals get lost or stolen by irresponsible people. Owners can look for themselves to the nearest environment, ask people around, to make announcement posters at strategic places. Searching in this way takes a lot of time and effort and the pets you are looking for are not necessarily found immediately. So we need an application and an animal tracking device in order to find out the location of the animal’s whereabouts, one of which is by using a tracking device that utilizes the Global Positioning System (GPS). This study aims to implement geofencing technology for pet tracking using Android-based Arduino. The application development stage includes analysis, system design, implementation, and testing. This program is implemented using U-Blox Neo 6M to track location with GPS network, SIM800L is used to send coordinate point data to trackers using GPRS network, and Arduino pro mini to manage input and output processes from the system. The test results show the tools and applications can run well. The android based pet tracker that is made can receive notification when a pet goes out of a predefined geofence limit.

Design, implementation, and evaluation of a shared LoRa network application architecture

This research proposes an internet of things application architecture based on the essence of 'sharing and reciprocity' - a shared LoRa network application architecture. To prove the feasibility of this architecture, we designed and implemented a pet tracking system which consists of the LoRa tracking motes, the fixed and portable shared LoRa gateways, a service mobile app, and the back-end service, exploiting technologies such as LoRa, Global Positioning System, Bluetooth Low Energy, Arduino UNO microcontroller, mobile app, and RESTful API. Moreover, this research evaluates the performance of the shared LoRa network and the electricity consumption of the LoRa tracking mote as well as the portable shared LoRa gateway. We confirm that the portable shared LoRa gateways do improve the overall network performance, and the users do not need to worry about the battery life of the devices in everyday life situations.

Design, implementation, and evaluation of a shared LoRa network application architecture

This research proposes an internet of things application architecture based on the essence of 'sharing and reciprocity' - a shared LoRa network application architecture. To prove the feasibility of this architecture, we designed and implemented a pet tracking system which consists of the LoRa tracking motes, the fixed and portable shared LoRa gateways, a service mobile app, and the back-end service, exploiting technologies such as LoRa, Global Positioning System, Bluetooth Low Energy, Arduino UNO microcontroller, mobile app, and RESTful API. Moreover, this research evaluates the performance of the shared LoRa network and the electricity consumption of the LoRa tracking mote as well as the portable shared LoRa gateway. We confirm that the portable shared LoRa gateways do improve the overall network performance, and the users do not need to worry about the battery life of the devices in everyday life situations.

Structure and Magnetic Properties of Layered Nanowires of 3d-Metals, Fabricated by the Matrix Synthesis Method

Based on PET track etched membranes, arrays of layer nanowires 100 nm in diameter, consisting of alternating Ni/Cu and Co/Cu layers are grown by the matrix synthesis method. Galvanic deposition processes are studied and conditions for fabricating layer nanowires with different thicknesses for magnetic (Ni or Co) and nonmagnetic (Cu) layer components are determined. An electron microscopic study is performed to verify conditions for fabricating layer nanowires and to correct geometrical sizes of alternating layers. Magnetization curves of produced arrays of layer nanowires are measured by vibration magnetometry methods at room temperature for two extreme orientations of a scanning magnetic field, i.e., parallel and perpendicular ones with respect to the nanowire growth axis. It is shown that the magnetic anisotropy of the nanowire array is controlled not only by the chemical composition, but also the thickness and alternation period of magnetic metal layers in nanowires. The dependence of the magnetostatic energy and demagnetizing field in the synthesized layer nanowires on the magnetic metal filling factor is numerically evaluated; the results are in qualitative agreement with experimental observations.

Noninvasive PET Imaging and Tracking of Engineered Human Muscle Precursor Cells for Skeletal Muscle Tissue Engineering.

Transplantation of human muscle precursor cells (hMPCs) is envisioned for the treatment of various muscle diseases. However, a feasible noninvasive tool to monitor cell survival, migration, and integration into the host tissue is still missing. In this study, we designed an adenoviral delivery system to genetically modify hMPCs to express a signaling-deficient form of human dopamine D2 receptor (hD2R). The gene expression levels of the receptor were evaluated by reverse transcriptase polymerase chain reaction, and infection efficiency was evaluated by fluorescent microscopy. The viability, proliferation, and differentiation capacity of the transduced cells, as well as their myogenic phenotype, were determined by flow cytometry analysis and fluorescent microscopy. (18)F-fallypride and (18)F-fluoromisonidazole, two well-established PET radioligands, were assessed for their potential to image engineered hMPCs in a mouse model and their uptakes were evaluated at different time points after cell inoculation in vivo. Biodistribution studies, autoradiography, and PET experiments were performed to determine the extent of signal specificity. To address feasibility for tracking hMPCs in an in vivo model, the safety of the adenoviral gene delivery was evaluated. Finally, the harvested tissues were histologically examined to determine whether survival of the transplanted cells was sustained at different time points. Adenoviral gene delivery was shown to be safe, with no detrimental effects on the primary human cells. The viability, proliferation, and differentiation capacity of the transduced cells were confirmed, and flow cytometry analysis and fluorescent microscopy showed that their myogenic phenotype was sustained. (18)F-fallypride and (18)F-fluoromisonidazole were successfully synthesized. Specific binding of (18)F-fallypride to hD2R hMPCs was demonstrated in vitro and in vivo. Furthermore, the (18)F-fluoromisonidazole signal was high at the early stages. Finally, sustained survival of the transplanted cells at different time points was confirmed histologically, with formation of muscle tissue at the site of injection. Our proposed use of a signaling-deficient hD2R as a potent reporter for in vivo hMPC PET tracking by (18)F-fallypride is a significant step toward potential noninvasive tracking of hD2R hMPCs and bioengineered muscle tissues in the clinic.

Experimental Study of Sliding Friction for PET Track Membranes

The article is presented results of a study of the process for a dry friction metal-polymer couple on scheme disc-finger. Track membrane from polyethylene terephthalate was a research material. Membrane had pores with 0.4 and 0.8 μm diameters. The effect of the sliding velocity for membranes with pores of 0.8 microns was determined. Research was shown that increasing pore’s diameter caused a reduction of the friction coefficient and downturn its magnitude vibrations. The study showed that track membrane have adequate resistance to wear and can be successfully used in surgical procedures in the layers of the cornea.

Dielectric and optical properties of a poly(ethylene terephthalate) membrane in the temperature interval 150–400 K

ABSTRACTIn this study, the dielectric and optical properties of poly(ethylene terephthalate) (PET) membranes were examined. The dielectric measurements were carried out in the temperature interval 150–400 K and in the frequency range 20 Hz–60 kHz. We analyzed in detail the temperature dependences of the dielectric permittivity and dielectric loss (tan δ) at various test frequencies. The relaxation tan δ peak, which appeared in the temperature range 150–300 K, was identified as the secondary β relaxation. The increase in tan δ at temperatures higher than 300 K could be explained as approaching the α relaxation. Optical measurements were performed in the UV–visible region from 200 to 400 nm at various temperatures between 150 and 400 K. The values of the direct and indirect band gaps were calculated at various temperatures. These values were lower for higher temperatures. An absorption peak was observed at a wavelength around of 285 nm at temperatures lower than 300 K. Such insight into the dielectric and optical responses of PET track membranes in a wide temperature range is particularly important when this material is used as a matrix for the semiconductor structure in the development of optoelectronic or microfluid devices. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42834.

Microbe–mineral interactions: The impact of surface attachment on mineral weathering and element selectivity by microorganisms

One of the major gaps within the field of biogeochemistry is the lack of a detailed and deep understanding of the mechanism behind the microbial inducement of mineral dissolution. The association of microorganisms with the mineral surfaces is an important issue for understanding processes like mineral weathering, biomineralization, bioremediation and biofouling. The present study aims to investigate the performance of attached and unattached soil fungal and bacterial species in biotite weathering and in the selectivity of elements from biotite. Sterilized microplate devices were filled with biotite (>2mm) followed by an iron limited liquid growth medium and were inoculated separately with six different microbial species isolated from podzol soil: Erwinia amylovora, Pseudomonas stutzeri, Pseudomonas mendocina, Streptomyces pilosus, Neurospora crassa and Penicillium melinii. The experiment was designed in two set-ups: 1) attached form, in which the microorganisms were inoculated directly to the biotite surface, and 2) unattached form, in which 0.4μm PET track etched devices were used to separate the microbial cells from the biotite surface.Our findings indicate that the surface attached microorganisms led to a greater dissolution of elements from biotite than the unattached microorganisms that was evidenced by 1) higher dissolution of Fe, Al and Si, 2) greater decrease in pH of the liquid growth medium, and 3) relatively higher production of siderophores. Furthermore, there was no significant difference in the capability of element selectivity between the attached and unattached microbial forms. The biotite dissolution was promoted initially by complexation processes and later by acidification processes for most of the attached and unattached microorganisms. Thus, we conclude that despite the mineral dissolution induced by microbial attachment on the mineral surface, the element composition of the biotite and nutritional need of the microorganisms were the main factors affecting the element selectivity.

Calculation of bulk etch rate’s semi-empirical equation for polymer track membranes in stationary and dynamic modes

One of the most urgent and extremely social problems in environmental safeties area in Kazakhstan is providing the population of all regions of the country with quality drinking water. Development of filter elements based on nuclear track-etch membranes may be considered as one of best solutions this problem. The values of bulk etch rate and activation energy were calculated in view the effect of temperature, alkaline solution concentration as well as stirring effect. The semi-empirical equation of the bulk etch rate for PET track membranes was calculated. As a result of theoretical and experimental studies a semi-empirical equation of the bulk etch rate V B =3.4∙10 12 ∙C 2.07 ∙exp(-0.825/kT) for 12 microns PET film, irradiated by ions 84 Kr 15+ (energy of 1.75 MeV/nucleon) at the heavy ion accelerator DC-60 in Astana branch of the INP NNC RK, was obtained.

Electrokinetic study of etching latent tracks of accelerated heavy ions in poly(ethylene terephthalate) and polyimide

The etching of latent tracks and pore formation in track membranes are studied. It is shown that the incorporation of K+ and Ba2+ ions into alkaline solutions accelerates the etching of poly(ethylene terephthalate) (PET) and latent tracks in it. The etching is accelerated due to a decrease in the negative surface charge of PET surface and the pores in track membranes. Isoelectric points are determined for PET and polyimide track membranes and it is established that they depend on pore diameter. As the pore diameter is enlarged from 30 to 70 nm, the magnitude of the negative surface charge rises seemingly due to the increase in the concentration of carboxyl groups on the pore surface. It is assumed that this effect is due to either a high mobility of carboxyl groups in a gel, which is formed on pore walls as a result of etching latent tracks, or a displacement of the slipping plane caused by a decrease in the thickness of the gel layer.

Influence of pore size and pore shape on thermo‐sensitive properties of poly[(ethylene terephthalate)‐graft‐(N‐isopropylacrylamide)] track membranes

AbstractBACKGROUND: The main aim of this work was to prepare poly[(ethylene terephthalate)‐graft‐(N‐isopropylacrylamide)] (PET‐graft‐NIPAAm) track membranes with various pore shapes and pore sizes, and to investigate the influence of pore shape and pore size on the thermo‐sensitive properties of the membranes. The PET‐graft‐NIPAAm track membranes were prepared using UV illumination, chemical etching and γ‐irradiation polymerization. Their thermo‐sensitive properties were investigated using conductimetry.RESULTS: PET track membranes with four kinds of pore shapes and sizes were prepared using chemical etching by changing the UV illumination time. After γ‐irradiation, NIPAAm was grafted into the etched PET track membranes both inside the pores and on the membranes. Conductimetric measurements showed that only membranes with appropriate pore shape and pore size had thermo‐sensitive properties. When the grafting ratio was 5 wt%, membranes with both small double cone‐shaped pores and with very large cylinder‐shaped pores showed no thermo‐sensitive properties.CONCLUSION: Along with the grafting ratio, the pore shape and pore size also have an influence on the thermo‐sensitive properties of PET‐graft‐NIPAAm track membranes. Copyright © 2009 Society of Chemical Industry

Modified track membranes with antibacterial properties

Microbiological contamination of polymeric membranes in the process of their exploitation is an essential problem of membrane technology. It results in the increase of manufacturing costs, destruction of membranes, operating life reduction and secondary contamination of water by the metabolism products of microorganisms. For the purpose of reduction of membrane biofouling and biodegradation investigation of adsorption of the guanidine containing oligomers on the surface of PET track membranes was conducted and their influence on the selectivity and antibacterial properties of the membranes was investigated. It was established that modified membranes have substantially higher resistance to biofouling.

Improvement of performances of PET track membranes by plasma treatment

Oxygen plasma grafting (I), allylamine and acrylic acid plasma grafting (II) and plasma polymerization (III) on poly(ethylene terephthalate) porous membranes led to water contact angle and surface energy in the range of 10–35° and 35–45 mN m −1 respectively. Treatment III gave a nonconsistent deposited layer that blocked the pores (0.2 μm) . Treatments I and II increased the water flow without affecting the rejection percentage of different molecular weight dextranes. Pore size, flow, adsorption of Rhodamine B were determined for the treated membranes. Best results were obtained using oxygen plasma pretreatment followed by 3 min of a vapour acrylic acid flow.

Track method for personal dosimetry for a nuclear-powered fleet

This work presents the development results of a high-sensitivity personal neutron track dosimeter for nuclear-powered ice-breakers. The dosimeter consists of a uranium-235 target and PET track detector in cadmium filters. Dose per track value of the dosimeter is 0.012 mrem fission −1 with scattering of 15%, affording a minimum measurable dose of 0.1 mrem. The main characteristics of this dosimeter are compared with the TLD-albedo ALNOR dosimeter.

Measurement of low neutron-fluences using electrochemically etched PC and pet track detectors

Systematic investigations have been carried out to study different properties of electrochemically etched (ECE) polycarbonate (PC) and polyethylene-terephthalate (PET) foils. The dependence of the density of background discharge spots on surface-thickness removal, electrical field strength and frequency of voltage is given. The effect of these parameters on the neutron sensitivity of polycarbonate and polyethylene-terephthalate foils irradiated at right angles to 14.7 MeV, 241Am-Be and 252Cf neutrons is also studied. With knowledge of the background and sensitivity data, the etching and electrical parameters are optimized for low neutron-fluence measurements.