Quasi-real-time range monitoring by in-beam PET: a case for 15O

A fast and reliable range monitoring method is required to take full advantage of the high linear energy transfer provided by therapeutic ion beams like carbon and oxygen while minimizing damage to healthy tissue due to range uncertainties. Quasi-real-time range monitoring using in-beam positron emission tomography (PET) with therapeutic beams of positron-emitters of carbon and oxygen is a promising approach. The number of implanted ions and the time required for an unambiguous range verification are decisive factors for choosing a candidate isotope. An experimental study was performed at the FRS fragment-separator of GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany, to investigate the evolution of positron annihilation activity profiles during the implantation of [Formula: see text]O and [Formula: see text]O ion beams in a PMMA phantom. The positron activity profile was imaged by a dual-panel version of a Siemens Biograph mCT PET scanner. Results from a similar experiment using ion beams of carbon positron-emitters [Formula: see text]C and [Formula: see text]C performed at the same experimental setup were used for comparison. Owing to their shorter half-lives, the number of implanted ions required for a precise positron annihilation activity peak determination is lower for [Formula: see text]C compared to [Formula: see text]C and likewise for [Formula: see text]O compared to [Formula: see text]O, but their lower production cross-sections make it difficult to produce them at therapeutically relevant intensities. With a similar production cross-section and a 10 times shorter half-life than [Formula: see text]C, [Formula: see text]O provides a faster conclusive positron annihilation activity peak position determination for a lower number of implanted ions compared to [Formula: see text]C. A figure of merit formulation was developed for the quantitative comparison of therapy-relevant positron-emitting beams in the context of quasi-real-time beam monitoring. In conclusion, this study demonstrates that among the positron emitters of carbon and oxygen, [Formula: see text]O is the most feasible candidate for quasi-real-time range monitoring by in-beam PET that can be produced at therapeutically relevant intensities. Additionally, this study demonstrated that the in-flight production and separation method can produce beams of therapeutic quality, in terms of purity, energy, and energy spread.

Production and separation of positron emitters for hadron therapy at FRS-Cave M

The FRagment Separator FRS at GSI is a versatile spectrometer and separator for experiments with relativistic in-flight separated short-lived exotic beams. One branch of the FRS is connected to the target hall where the bio-medical cave (Cave M) is located. Recently a joint activity between the experimental groups of the FRS and the biophysics at the GSI and Department of physics at LMU was started to perform biomedical experiments relevant for hadron therapy with positron emitting carbon and oxygen beams. This paper presents the new ion-optical mode and commissioning results of the FRS-Cave M branch where positron emitting ¹⁵O-ions were provided to the medical cave for the first time. An overall conversion efficiency of 2.9±0.2×10^{-4 15}O fragments per primary ¹⁶O ion accelerated in the synchrotron SIS18 was reached.

Precision of the PET activity range during irradiation with10C,11C, and12C beams

Objective. Beams of stable ions have been a well-established tool for radiotherapy for many decades. In the case of ion beam therapy with stable¹²C ions, the positron emitters^10,11C are produced via projectile and target fragmentation, and their decays enable visualization of the beam via positron emission tomography (PET). However, the PET activity peak matches the Bragg peak only roughly and PET counting statistics is low. These issues can be mitigated by using a short-lived positron emitter as a therapeutic beam.Approach.An experiment studying the precision of the measurement of ranges of positron-emitting carbon isotopes by means of PET has been performed at the FRS fragment-separator facility of GSI Helmholtzzentrum für Schwerionenforschung GmbH, Germany. The PET scanner used in the experiment is a dual-panel version of a Siemens Biograph mCT PET scanner.Main results.High-quality in-beam PET images and activity distributions have been measured from the in-flight produced positron emitting isotopes¹¹C and¹⁰C implanted into homogeneous PMMA phantoms. Taking advantage of the high statistics obtained in this experiment, we investigated the time evolution of the uncertainty of the range determined by means of PET during the course of irradiation, and show that the uncertainty improves with the inverse square root of the number of PET counts. The uncertainty is thus fully determined by the PET counting statistics. During the delivery of 1.6 × 10⁷ions in 4 spills for a total duration of 19.2 s, the PET activity range uncertainty for¹⁰C,¹¹C and¹²C is 0.04 mm, 0.7 mm and 1.3 mm, respectively. The gain in precision related to the PET counting statistics is thus much larger when going from¹¹C to¹⁰C than when going from¹²C to¹¹C. The much better precision for¹⁰C is due to its much shorter half-life, which, contrary to the case of¹¹C, also enables to include the in-spill data in the image formation.Significance. Our results can be used to estimate the contribution from PET counting statistics to the precision of range determination in a particular carbon therapy situation, taking into account the irradiation scenario, the required dose and the PET scanner characteristics.

Rapid assembly of heterocycle grafted macrocycles via tandem one-pot double 1,3-dipolar cycloaddition reaction

Synthesis of triazole linked macrocycles grafted with glycospiroheterocycle was accomplished by stereo- and regioselective tandem double 1,3-dipolar cycloaddition (1,3-DC) reaction.

Automated laboratory based X-ray beamline with multi-capillary sample chamber

An automated laboratory based X-ray beamline with a multi-capillary sample chamber capable of undertaking small angle X-ray scattering measurements on a maximum of 104 samples at a time as a function of temperature between 5 and 85 °C has been developed. The modular format of the system enables the user to simultaneously equilibrate samples at eight different temperatures with an accuracy of ±0.005 °C. This system couples a rotating anode generator and 2D optoelectronic detector with Franks X-ray optics, leading to typical exposure times of less than 5 min for lyotropic liquid crystalline samples. Beamline control including sample exchange and data acquisition has been fully automated via a custom designed LabVIEW framework.

{1'-Phenyl-1',2',5',6',7',7a'-hexa-hydro-spiro-[indeno-[1,2-b]quinoxaline-11,3'-pyrrolizin]-2'-yl}(p-tol-yl)methanone

In the title compound, C(35)H(29)N(3)O, the quinoxaline and indene systems are essentially planar, with maximum deviations of 0.047 (2) and 0.032 (2) Å for C atoms, respectively. The quinoxaline system forms a dihedral angle of 4.75 (3)° with the indene system. The pyrrolizine system is folded. The substituted five-membered ring adopts an envelope conformation. In the other five-membered ring, one C atom is disordered with a site-occupancy ratio of 0.676 (12):0.324 (12). In the crystal, mol-ecules are linked via C-H⋯O hydrogen bonds involving the bifurcated carbonyl O atom.

3'-(4-Chloro-benzo-yl)-4'-(4-chloro-phen-yl)-1'-methyl-spiro-[indoline-3,2'-pyrrolidin]-2-one

In the title compound, C₂₅H₂₀Cl₂N₂O₂, the pyrrolidine ring adopts an envelope conformation and the best plane through the five ring atoms makes a dihedral angle of 87.03 (8)° with the indoline ring. Mol­ecules are connected by pairs of N—H⋯O hydrogen bonds into centrosymmetric dimers with an R₂²(8) graph-set ring motif. C—H⋯O hydrogen bonds stabilize the crystal structure.

4,9-Dioxa-1,3(1,2)-dibenzena-2(4,5)-1,3-oxazolidinacyclononaphane

The oxazole ring in the title compound, C₂₀H₂₃NO₃, adopts an envelope conformation while the 12-membered ring is in a chair conformation. The dihedral angle between the benzene rings is 37.8 (1)°. The crystal structure displays inter­molecular C—H⋯O hydrogen bonding.

Factors Affecting Metal/Polymer Interface Durability in Microelectronics Packaging: Chemistry and Water Uptake

Durability of metal/polymer interfaces is essential for the long-term reliability of high performance microelectronics packages. Such interfaces undergo stresses during production and in service. In this work, we report on the durability of interfaces formed between reactive metals and polyimides (PI) that have been subjected to stresses simulating both types of environment. The P1 surfaces were treated by Ar RF plasmas prior to metal deposition, and durability was determined by measuring the 90 degree peel strength as a function of environmental exposure. The durability of Cr and Ti/PMDA-ODA interfaces through processing stresses (i.e., large thermal excursions) depends on the PI surface modification and the metal reactivity. For both, we observed interfacial degradation due to oxidation of the metal–the cause is water absorbed by the polyimide. These studies, coupled with water transport measurements, suggest that the physical structure of the interface is the dominant factor. To determine the durability under service environmental stresses (e.g., temperature/humidity), we correlated peel strengths with interfacial chemistry and water uptake. In this case, Ar and O2 plasmas were used. For Ta/BPDA-PDA, the durability depends on the type of plasma treatment. Ar-treated specimens maintain strength through 500 hours T/H stressing whereas those treated by O2 plasma alone fail at 165 hours. The differences here can be explained by the interfacial chemistry–Ta/Ar-etched surfaces form a stable TaG-like structure whereas the Ta/O2-etched surfaces form a metastable, sub-oxide structure that transforms to Ta2O5 during stressing. Ta/PMDA-ODA interfaces fail readily under these conditions due to the increased water uptake of the PI.

Corn steep liquor as a nutrition adjunct for the production of Aspergillus niger lipase and hydrolysis of oils thereof

Corn steep liquor (CSL) has been used as a nutrition adjunct for the production of an extracellular lipase from Aspergillus niger, which has immense importance as an additive in laundry detergent formulations. A five-level four-factorial central composite design was chosen to determine the optimal medium components with four critical variables, namely, CSL, NH4H2PO4, Na2HPO4, and sesame oil, that were found to be influential for lipase production by the classical one-factor-at-a-time method. The model suggested that all of the factors chosen had a significant impact on lipase production, and the optimum values of the influential parameters were CSL, 2.0%, w/v; NH4H2PO4, 0.05%, w/v; Na2HPO4, 0.75%, w/v; and sesame oil, 2.0%, w/v, with an activity of 26.7 U/mL at 48 h and 30 degrees C, which was 2.16-fold higher than the initial activity (12 U/mL) obtained by the conventional one-factor-at-a-time method. Furthermore, the enzyme has good potential for the hydrolysis of vegetable oils and fish oils, and a hydrolytic ratio of 88.73% was obtained with palm oil at 48 h. The utilization of CSL and sesame oil for lipase production from A. niger makes the process green, because both are renewable substrates and economically viable at an industrial scale.

2,4,8-Trioxa-2-aza-1,3,6(1,2)-tri-benzena-2(2,3)-bicyclo-[3.3.0]octa-na-cyclo-octa-phane

The crystal structure of the title compound, C₂₆H₂₅NO₃, was determined as part of an investigation of host–guest and electron donor–acceptor complexes. The oxazole and the pyrrole rings both adopt envelope conformations. The dihedral angle between the two benzene rings directly linked to the oxazole ring is 49.5 (1)°. The crystal structure is stabilized by a C—H⋯π inter­action.

Liquid crystal alignment on carbonaceous surfaces with orientational order

We used near-edge x-ray absorption fine structure (NEXAFS) spectroscopy to link the orientational bond order at three carbonaceous surfaces-rubbed polyimide, ion beam-irradiated polyimide, and ion beam-irradiated diamondlike carbon films-with the direction of liquid crystal (LC) alignment on these surfaces. We show that, in general, LC alignment can be created on any carbonaceous substrate by inducing orientational order at its surface. Our results form the scientific basis for LC alignment layers consisting of amorphous carbon films in which orientational order near the surface is induced by a directional low-energy ion beam.

Atomic-beam alignment of inorganic materials for liquid-crystal displays

The technique used to align liquid crystals-rubbing the surface of a substrate on which a liquid crystal is subsequently deposited-has been perfected by the multibillion-dollar liquid-crystal display industry. However, it is widely recognized that a non-contact alignment technique would be highly desirable for future generations of large, high-resolution liquid-crystal displays. A number of alternative alignment techniques have been reported, but none of these have so far been implemented in large-scale manufacturing. Here, we report a non-contact alignment process, which uses low-energy ion beams impinging at a glancing angle on amorphous inorganic films, such as diamond-like carbon. Using this approach, we have produced both laptop and desktop displays in pilot-line manufacturing, and found that displays of higher quality and reliability could be made at a lower cost than the rubbing technique. The mechanism of alignment is explained by adopting a random network model of atomic arrangement in the inorganic films. Order is induced by exposure to an ion beam because unfavourably oriented rings of atoms are selectively destroyed. The planes of the remaining rings are predominantly parallel to the direction of the ion beam.

Low-voltage organic transistors on plastic comprising high-dielectric constant gate insulators

The gate bias dependence of the field-effect mobility in pentacene-based insulated gate field-effect transistors (IGFETs) was interpreted on the basis of the interaction of charge carriers with localized trap levels in the band gap. This understanding was used to design and fabricate IGFETs with mobility of more than 0.3 square centimeter per volt per second and current modulation of 10(5), with the use of amorphous metal oxide gate insulators. These values were obtained at operating voltage ranges as low as 5 volts, which are much smaller than previously reported results. An all-room-temperature fabrication process sequence was used, which enabled the demonstration of high-performance organic IGFETs on transparent plastic substrates, at low operating voltages for organic devices.

Prospects and problems of intermittent irrigation for control of vector breeding in rice fields in southern India

The impact of water management on the abundance and interaction of aquatic stages of mosquitoes and some important groups of their predators was studied in a 22.3-ha plot of rice in southern India. Many pools persisted even in a year when intermittent irrigation (II) was properly implemented (fields being re-irrigated as soon as they were dry) and these acted as microrefuges for the immature stages of mosquitoes and for their predators. Although the abundance of all predators, particularly of Notonectidae, was reduced by II in this year, increased predation efficiency in the confined spaces of the persistent pools resulted in a 75%-88% reduction in the abundance of mosquito pupae, as measured by two independent sampling methods. In another year there was insufficient irrigation water for proper II and re-irrigation took place whenever water was available rather than when it was required, frequently resulting in only partial drying. This reduced predator populations without enhancing their efficiency, and so mosquito abundance was slightly higher than in conventionally irrigated fields. The implications for vector control are discussed.