Crystallization of polyethylene terephthalate in injection moulding : experiments, modelling and numerical simulation.

Crystallization of polyethylene terephthalate in injection moulding : experiments, modelling and numerical simulation.

In-beam Positron Emission Tomography (PET) is a system for monitoring high precision radiation therapy which is in the most cases applied to the tumors near organs at risk. High quality and fast availability of in-beam PET images are, therefore, extremely important for successful verification of the dose delivery. Two main problems make an in-beam PET monitoring a challenging task. Firstly, in-beam PET measurements result in a very low counting statistics. Secondly, an integration of the PET scanner into the treatment facility requires significant reduction of the sensitive surface of the scanner and leads to a dual-head form resulting in imaging artifacts. The aim of this work is to bring the imaging process by means of in-beam PET to optimum quality and time scale. The following topics are under consideration: - analysis of image quality for in-beam PET; - image reconstruction; - solutions for building, testing, and integration of a PET monitoring system into the dedicated treatment facility.

Thesis (M. Arch.)--University of Hong Kong, 1997. / Includes special report study entitled: Vertical garden in urban context. Includes bibliographical references.

Background: Gliomas are neuroepithelial tumours classified by cell type and grade. In adults, low-grade gliomas are comprised mainly of astrocytomas and oligodendrogliomas grade II. The aim was to non-invasively characterise suspected low-grade gliomas through use of 11C-methionine-PET and physiological MRI in order to facilitate treatment decisions. Materials and methods: Patients with suspected low-grade glioma were prospectively and consecutively included after referral to the Neurosurgical Department, Uppsala University Hospital, between February 2010 and February 2014. All patients underwent morphological MRI, perfusion MRI, diffusion MRI and 11C-methionine PET. The institutional review board approved the study, and written informed consent was obtained prior to participation from each patient. Results: 11C-methionine PET hot spot regions corresponded spatially with regions of maximum relative cerebral blood volume in dynamic susceptibility contrast (DSC) perfusion MRI. The skewness of the transfer constantin dynamic contrast-enhanced (DCE) perfusion MRI, and the standard deviation of relative cerebral blood flow in DSC perfusion MRI could most efficiently discriminate between glioma grades II and III. In diffusion MRI, tumour fractional anisotropy differed between suspected low-grade gliomas of different neuropathological types. Quantitative diffusion tensor tractography was applicable for the evaluation of tract segment infiltration. Conclusion: PET and physiological MRI are able to characterise low-grade gliomas and are promising tools for guiding therapy and clinical decisions before neuropathological diagnosis has been obtained.

Šiame darbe nuodugniai ištirtos gamybinių polietilentereftalato (PET) atliekų susidarymo vietos, priežastys bei jų savybės. Pasiūlyti skirtingi cheminio perdirbimo būdai ir sąlygos kiekvienai gamybinių PET atliekų rūšiai. Vykdant gamybinių PET atliekų glikolizę etilenglikoliu, pasiekta didesnė negu 85 % bis(2-hidroksietilen)tereftalatо išeiga. Peresterinant gamybines PET atliekas dietilenglikoliu (DEG) ir naudojant funkcinius priedus glicerolį (GL) ir/arba adipo rūgštį (ADR), susintetinta serija aromatinių poliesterpoliolių (APP), besiskiriančių savo klampa ir kitomis savybėmis. Pirmą kartą nuodugniai ištirta ir matematiškai aprašyta peresterinimo reakcijos mišinyje esančių funkcinių priedų įtaka APP klampai. APP, susintetinti peresterinant gamybines PET atliekas DEG ir turintys ADR ir/arba GL fragmentų, yra mažai linkę kristalintis ir stabilūs saugant juos kambario temperatūroje. APP klampa mažai priklauso nuo metaloorganinio katalizatoriaus cheminės sudėties ir jo koncentracijos. Naudojant PET peresterinimo metu gautus APP ir diizocianato perteklių, susintetintos poliuretano-poliizocianurato (PU-PIR) putos. Putos, gautos iš APP, kuriuose yra GL ir/arba ADR fragmentų, pasižymi geromis fizikomechaninėmis savybėmis ir dideliu terminiu stabilumu, joms degant išsiskiria mažesnis šilumos ir dūmų kiekis. Atliekant degumo bandymus nustatyta, kad PU-PIR putos atitinka reikalavimus, taikomus Е klasės statybinėms konstrukcijoms ir elementams. / In this study, the generation points, reasons and properties of industrial PET waste were examined in detail. Different chemical recycling ways were suggested for each kind of industrial PET waste. Under glycolysis of industrial PET waste by ethylene glycol, the yield of the main product bis(2-hidroxyethylene) terephthalate was higher than 85 %. Several series of aromatic polyester polyols (APP) were synthesized by transesterification of industrial PET waste using diethyleneglycol (DEG) in the presence of functional additives glycerol (GL) or/and adipic acid (ADA). The effect of functional additives on transesterification process and viscosity of APP was thoroughly studied and mathematically described for the first time. APP synthesized by transesterification of industrial PET waste using DEG in the presence of ADA and/or GL fragments, had lower crystallinity and were much more stable during storage at room temperature. Viscosity of APP slightly depended on the catalyst type and its concentration. Polyurethane-polyisocyanurate (PU-PIR) foams were produced under the reaction of APP and an excess of diisocyanate. PU-PIR foams based on PET-waste-derived APP containing fragments of GL or/and ADA were characterized by excellent physical-mechanical properties, high thermal stability, low heat release and smoke production. The burning test confirmed that PU-PIR foams satisfied the requirements for class E of construction products and building elements.

In this study, the generation points, reasons and properties of industrial PET waste were examined in detail. Different chemical recycling ways were suggested for each kind of industrial PET waste. Under glycolysis of industrial PET waste by ethylene glycol, the yield of the main product bis(2-hidroxyethylene) terephthalate was higher than 85 %. Several series of aromatic polyester polyols (APP) were synthesized by transesterification of industrial PET waste using diethyleneglycol (DEG) in the presence of functional additives glycerol (GL) or/and adipic acid (ADA). The effect of functional additives on transesterification process and viscosity of APP was thoroughly studied and mathematically described for the first time. APP synthesized by transesterification of industrial PET waste using DEG in the presence of ADA and/or GL fragments, had lower crystallinity and were much more stable during storage at room temperature. Viscosity of APP slightly depended on the catalyst type and its concentration. Polyurethane-polyisocyanurate (PU-PIR) foams were produced under the reaction of APP and an excess of diisocyanate. PU-PIR foams based on PET-waste-derived APP containing fragments of GL or/and ADA were characterized by excellent physical-mechanical properties, high thermal stability, low heat release and smoke production. The burning test confirmed that PU-PIR foams satisfied the requirements for class E of construction products and building elements. / Šiame darbe nuodugniai ištirtos gamybinių polietilentereftalato (PET) atliekų susidarymo vietos, priežastys bei jų savybės. Pasiūlyti skirtingi cheminio perdirbimo būdai ir sąlygos kiekvienai gamybinių PET atliekų rūšiai. Vykdant gamybinių PET atliekų glikolizę etilenglikoliu, pasiekta didesnė negu 85 % bis(2-hidroksietilen)tereftalatо išeiga. Peresterinant gamybines PET atliekas dietilenglikoliu (DEG) ir naudojant funkcinius priedus glicerolį (GL) ir/arba adipo rūgštį (ADR), susintetinta serija aromatinių poliesterpoliolių (APP), besiskiriančių savo klampa ir kitomis savybėmis. Pirmą kartą nuodugniai ištirta ir matematiškai aprašyta peresterinimo reakcijos mišinyje esančių funkcinių priedų įtaka APP klampai. APP, susintetinti peresterinant gamybines PET atliekas DEG ir turintys ADR ir/arba GL fragmentų, yra mažai linkę kristalintis ir stabilūs saugant juos kambario temperatūroje. APP klampa mažai priklauso nuo metaloorganinio katalizatoriaus cheminės sudėties ir jo koncentracijos. Naudojant PET peresterinimo metu gautus APP ir diizocianato perteklių, susintetintos poliuretano-poliizocianurato (PU-PIR) putos. Putos, gautos iš APP, kuriuose yra GL ir/arba ADR fragmentų, pasižymi geromis fizikomechaninėmis savybėmis ir dideliu terminiu stabilumu, joms degant išsiskiria mažesnis šilumos ir dūmų kiekis. Atliekant degumo bandymus nustatyta, kad PU-PIR putos atitinka reikalavimus, taikomus Е klasės statybinėms konstrukcijoms ir elementams.

Introduction 76Br is of interest for in vivo PET imaging applications. Its relatively long half-life (16.1 h) allows use not only on small molecules but also proteins which have slow excretion as carrier molecules. Irradiation using a low energy proton beam (~ 20 MeV) on an enriched Cu276Se target, followed by dry distillation with thermal chromatography, is one of the best methods to obtain sufficient amounts of 76Br for clinical applications1,2. However, the thermal chromatography is plagued by poor reproducibility and appears unsuitable for automation of its production, leading us to remove the thermal chroma-tography from the dry distillation. In this investigation we employed H2O solution to collect 76Br and optimized the distillation condition using a small amount of 77Br (57.0 h). We also produced large amount of 76Br under the optimized conditions to evaluate the dry distillation method. Material and Methods Target preparation and dry distillation were conducted based on the methods described in previous reports1,2. To produce 77Br, Cu2natSe target was irradiated with 20 MeV proton beams (5 µA) accelerated by AVF cyclotron in the Japan Atomic Energy Agency. The following two systems were used in the dry distillation optimization studies; (1) an initial system was composed of two furnaces, a main and an auxiliary furnace. Temperature of each furnace was set at 1050 °C (main) and 200 °C (auxiliary) respectively; (2) the second system was made of one large furnace composed of heating and cooling area. Temperature of the heating area was varied from 1050 to 1120 °C. In both systems PTFE tubing, leading to a H2O solution (15 mL), was inserted into the apparatus. The irradiated target was heated under streaming Ar gas (30 mL/min.). An enriched Cu276Se target (76Se enrichment: 99.67%) was used for 76Br production. Radioactivity was measured on a high-purity germanium (HPGe) detector coupled to a multichannel analyzer. TLC analyses were conducted on Al2O3 plates (Merck) using 7:1 acetone:H2O as the eluting solvent. Results and Conclusion Low efficiency (33 %) of 77Br recovery was ob-served in the initial system. Distribution of radioactivity inside the apparatus showed that 35 % was trapped in the PTFE tube and the quartz tube. The recovery yield was increased up to 54 % when the auxiliary furnace was turned off, indicating that the temperature gradient inside the quartz tube is suitable to carry 77Br effectively to the H2O trap. We initially used a quartz boat to place the irradiated target in the furnace, but found that using a reusable tungsten backing was better. However, we found that recovery yield was dramatically reduced to 18 %. The studies where the temperature was varied showed that releasing efficiency was increased up to 100 % at the temperature of 1120 °C. Good recovery yield (~ 77 %) was achieved after optimizing the temperature gradient (FIG. 1b). Using the optimized setup, 76Br production runs (n = 6) have been conducted, allowing us to recover up to 39.8 MBq/µAh (EOB) of 76Br. High specific activity (~4400 GBq/µmol) was obtained in the final solution. TLC analysis showed that chemical form obtained was bromide. We concluded that the dry distillation using H2O trap is capable of providing enough high purity 76Br for clinical applications.

Introduction The worldwide use of PET has proven beyond dispute the importance for both routine diagnosis and physiological, oncological and pharmacological research. In many ways the present success of PET relies on the mature technology of PET compact medical cyclotrons. As long time developers of new targets, isotopes and com-pounds, we have been inclined to look for new block-buster applications, high power targets and sustainable ways of embracing the GMP and regional distribution, but recent pioneering development [1] around very small cyclotrons and “embedded synthesis and qc” has pointed out an old, but important nuclear physics lesson now halfway forgotten: that many PET isotopes can be made in high yields with proton energies far below 10 MeV [2]. This has opened a new interest in small cyclotrons and their targets. We have been testing the first GE Healthcare Prototype for a 7.8 MeV negative ion, internal ion source cyclotron with 3 production targets mounted on a short beamline. Here we present the first experimental yields of some of the important PET radionuclides. Materials and methods The prototype cyclotron (FIG. 1) has been in-stalled and tested without self-shield in designated experimental area in order to establish the neutron field around accelerator and targets in order to qualify design calculations for a future integrated shield. The cyclotron energy is fixed by the radial position of the extraction foil, while the azimuth determines which of the 3 targets are being irradiated. The beam energy at front of target foil was determined on several occasions: 7.8 ± 0.1 MeV by a 2 copper-foil sandwich method (adopted from [3]). The available beam inside the cyclotron at extractor position is > 50 μA, and 35 μA are easily and long term reliably extracted (> 90 %) on to any of the 3 target positions. The prototype is capable of delivering more than 40 μA to target, but target current was limited to 35 μA under present unshielded conditions. Results 18F We have tested the prototype gridded (> 80 % transmission) niobium body target with 10μm Havar foil using 95 % 18O water and 35 μA on target + grid with yields given in TABLE 1. The observed yields corrected for stopping in foil, grid loss and water enrichment are 75 % of theoretical. One Fastlab FDG run using 2 h irradiation yielded 16 GBq FDG EOS, confirming the “usual” 18F activity. Results 11C Using gridded target and a 10μm foil with 99% N2 + 1 % O2 at 10 bar followed by trapping into ascarite gave EOB activity as shown in TABLE 2. Results 13N We know that the 16O(p,alpha)13N cross section is a very steep function of energy around 7.8 MeV. In the hope of using the simple water target route to 13N NH3 we have measured the 13N yields (corrected for 18F contribution). It is still unclear if these yields can be improved to make useful single doses of ammonia. Results for other isotopes We have used solid targets to make 45Ti, 64Cu, 68Ga and 89Zr. The development of these solid targets is still in progress, but especially the 68Ga yield looks promising (3 GBq EOB after 1 h on natural Zn will give > 15 GBq on enriched 68Zn).

Introduction Two current major research topics in nuclear medicine are in the development of long-lived positron-emitting nuclides for imaging tracers with long biological half-lives and in theranostics, imaging nuclides which have a chemically analogous therapy isotope. As shown in TABLE 1, the radioisotopes of arsenic (As) are well suited for both of these tasks with several imaging and therapy isotopes of a variety of biologically relevant half-lives accessible through the use of small medical cyclotrons. The five naturally abundant isotopes of germanium are both a boon and challenge for the medical nuclear chemist. They are beneficial in that they facilitate a wide array of producible radioarsenic isotopes. They are a challenge as monoisotopic radioarsenic production requires isotopically-enriched targets that are expensive and of limited availability. This makes it highly desirable that the germanium target material is reclaimed from arsenic isolation chemistry. One major factor which has limited the development of radioarsenic has been difficulties in its incorporation into biologically relevant targeting vectors. Previous studies have labeled antibodies and polymers through covalent bonding of arsenite (As(III)) with the sulfydryl group1,2,3. Recent work in our group has shown the facile synthesis and utility of superparamagnetic iron oxide nanoparticle- (SPION-)bound radioarsenic as a dual modality positron emission tomography (PET)/magnetic resonance imaging (MRI) agent4. Presently, we have built upon previous studies producing, isolating, and labeling untargeted SPION with radioarsenic4,5. We have incorp-rated the use of isotopically-enriched 72GeO2 for the production of radioisotopically pure 72As. The bulk of the 72GeO2 target material was re-claimed from the arsenic isolation chemical procedure for reuse in future irradiations. The 72As was used for ongoing development toward the synthesis of targeted, As-SPION-based, dual-modality PET/MRI agents. Material and Methods Targets of ~100 mg of isotopically-enriched 72GeO2 (96.6% 72Ge, 2.86% 73Ge, 0.35% 70Ge, 0.2% 74Ge, 0.01% 76Ge, Isoflex USA) were pressed into a niobium beam stop at 225 MPa, covered with a 25 µm HAVAR containment foil, attached to a water-cooling target port, and irradiated with 3 µA of 16.1 MeV protons for 2–3 hours using a GE PETtrace cyclotron. After irradiation, the target and beam stop were assembled into a PTFE dissolution apparatus, where the 72GeO2 target material was dissolved with the addition of 2 mL of 4 M NaOH and subsequent stirring. After dissolution was completed, the clear, colorless solution was transferred to a fritted glass column and the bulk 72GeO2 was reprecipitated by neutralizing the solution with the addition of 630 µL [HCl]conc, filtered, and rinsed with 1 mL [HCl]conc. To the combined 72As-containing filtrates, 100 µL 30% H2O2 was added to ensure that 72As was in the nonvolatile As(V) oxidation state. The ~3 mL solution was then evaporated at 115 ˚C while the vessel was purged with argon, followed by a second addition of 100 µL H2O2 after the volume was reduced to 1 mL. When the filtrate volume was ~0.3 mL, the vessel was removed from heat, allowed to cool with argon flow, and the arsenic reconstituted in 1 mL [HCl]conc and loaded onto a 1.5 mL bed volume Bio-Rad AG 1×8, 200–400 mesh anion exchange column preconditioned with 10 M HCl. The radioarsenic was eluted in 10 M HCl in the next ~10 mL, with 90% of the activity eluting in a 4 mL fraction. The column was then eluted with 5 mL 1 M HCl. The 72As-rich 10 M HCl fraction was reduced to As(III) with the addition of ~100 mg CuCl, and heating to 60 ˚C for 1 hour. The resulting AsCl3 was then extracted twice into 4 mL cyclohexane, which were combined and back extracted into 500 µL of water as As(OH)3. This solution of 72As in H2O was then used directly to label SPION and for subsequent experiments conjugating 72As-SPION with TRC105, an angiogenesis-marking monoclonal antibody (MAb) targeting endoglin/CD105. Several methods were initially attempted involving directly conjugating the surface-modified SPION to the MAb through a polyethylene glycol (PEG) linker. More recent studies have investigated the radioarsenic labeling of SPION encapsulated in hollow mesoporous silica nanoparticles (SPION@HMSN) and its subsequent conjugation to TRC105. Results and Conclusion Irradiation of pressed, isotopically-enriched 72GeO2 resulted in a production yield for 72As of 17 ± 2 mCi/(µA·hr·g) and for 71As of 0.37 ± 0.04 mCi/(µA·hr·g), which are 64 % and 33 %, of those predicted from literature6, respectively. However, these production yields are in agreement with those scaled from observed production yields using analagous natGeO2 targets. The end-of-bombardment 72As radionuclidic purity can be improved by minimizing the 72Ge(p,2n)71As reaction by degrading the beam energy. A 125 µm Nb containment foil would degrade impinging protons to 14.1 MeV and is predicted to reduce 71As yield by a factor of three, while only reducing 72As yield by 1 %6, improving end-of-bombardment radionuclidic purity from 98 % to greater than 99 %. Overall decay-corrected radiochemical yield of the 72As isolation procedure from 72GeO2 were 51 ± 2 % (n = 3) in agreement with those observed with natGeO2 57 ± 7 % (n = 14). The beam current was limited to 3 µA as higher cur-rents 4–5 µA exhibited inconsistent dissolution and reprecipitation steps, resulting in an overall yield of 44 ± 21 % (n = 6). Dissolution time also played an important role in overall yield with at least one hour necessary to minimize losses in these first two steps. The separation procedure effectively removed all radiochemical contaminants and resulted in 72As(OH)3 isolated in a small volume, pH~4.5 water solution. Over the course of minutes to hours after back extraction, rapid auto-oxidation to 72AsO4H3 was observed. The bulk 72GeO2 target material, which was reclaimed from the isolation procedure, is being collected for future use. The synthesis of a targeted PET/MRI agent based on the functionalization of 72As-SPION has proved to be a difficult task. Experiments conjugating 72As-SPION to TRC105 through a PEG linker were unsuccessful, despite the investigation of a variety bioconjugation procedures. Current work is investigating the use of SPION@HMSN, which have a similar affinity for 72As as unencapsulated SPION. This new class of 72As-labeled SPION@HMSN has a hollow cavity for potential anti-cancer drug loading, as well as the mesoporous silica surface, which may facilitate the efficient conjugation of TRC105 using a well-developed bioconjugation technique. In summary, radioarsenic holds potential in the field of diagnostic and therapeutic nuclear medicine. However, this potential remains locked behind challenges related to its production and useful in vivo targeting. The present work strives to address several of these challenges through the use of enriched 72GeO2 target material, a chemical isolation procedure that reclaims the bulk of the target material, and the investigation of new targeted nanoparticle-based PET/MRI agents.