Thallium-bromide (TlBr) is currently under investigation for use as an alternative room-temperature semiconductor gamma-ray spectrometer. Performance of better than 1% full-width at half maximum at ...662 keV can be achieved when TlBr detectors are cooled to −20 °C. The theoretical limit of energy resolution is determined by the ionization energy in semiconductor detectors, and accurately measuring it is important for determining the best possible performance. One method to determine the ionization energy of semiconductor detectors compares pulse heights obtained from the semiconductor to pulse heights from a silicon detector. Due to their higher trapping, the charge collection efficiency (CCE) of TlBr is significantly lower than it is in silicon, therefore a correction to the ionization energy must be made. In this paper, we present the theory and measurement for accurately determining the CCE using the Shockley-Ramo theorem and apply it to measurement of ionization energy in pixelated TlBr detectors. The ionization energy of two TlBr detectors is measured and found to be 4.83(8) and 5.49(10) eV for the two samples at room temperature and −20 °C, respectively.
Georges Perec, novelist, filmmaker and essayist, was one of the
most inventive and original writers of the twentieth century. A
fascinating aspect of his work is its intrinsically geographical
...nature. With major projects on space and place, Perec's writing
speaks to a variety of geographical, urban and architectural
concerns, both in a substantive way, including a focus on cities,
streets, homes and apartments, and in a methodological way,
experimenting with methods of urban exploration and observation,
classification, enumeration and taxonomy.
Georges Perec's Geographies is the first book
to offer a rounded picture of Perec's geographical interests.
Divided into two parts, Part I, Perec's Geographies, explores the
geographies within Perec's work in film, literature and radio, from
descriptions of streets to the spaces of his texts, while Part II,
Perecquian Geographies, explores geographies in a range of material
and metaphorical forms, including photographic essays, soundscapes,
theatre, dance and writing, created by those directly inspired by
Perec.
Georges Perec's Geographies extends the body of Perec
criticism beyond Literary and French Studies to disciplines
including Geography, Urban Studies, Planning and Architecture to
offer a complete and systematic examination of Georges Perec's
geographies. The diversity of readings and approaches will be of
interest not only to Perec readers and fans but to students and
researchers across these subjects.
Halide perovskite semiconductors are poised to revitalize the field of ionizing radiation detection as they have done to solar photovoltaics. We show that all-inorganic perovskite CsPbBr3 devices ...resolve 137Cs 662-keV γ-rays with 1.4% energy resolution, as well as other X- and γ-rays with energies ranging from tens of keV to over 1 MeV in ambipolar sensing and unipolar hole-only sensing modes with crystal volumes of 6.65 mm3 and 297 mm3, respectively. We report the scale-up of CsPbBr3 ingots to up to 1.5 inches in diameter with an excellent hole mobility–lifetime product of 8 × 10−3 cm2 V−1 and a long hole lifetime of up to 296 μs. CsPbBr3 detectors demonstrate a wide temperature region from ~2 °C to ~70 °C for stable operation. Detectors protected with suitable encapsulants show a uniform response for over 18 months. Consequently, we identify perovskite CsPbBr3 semiconductor as an exceptional candidate for new-generation high-energy γ-ray detection.Energy resolution of high-energy photon detectors is desired for applications ranging from biomedical imaging to homeland security. In this work, perovskite-based γ-ray detection with 1.4% energy resolution is demonstrated.
Thallium bromide (TlBr) is an attractive material for room-temperature semiconductor radiation detection due to its high atomic number and density. Performance of better than 1% full-width at half ...maximum at 662 keV has been measured on <inline-formula> <tex-math notation="LaTeX">\sim 5 \times 5 \times 5 </tex-math></inline-formula> mm 3 pixelated TlBr detectors. Though most TlBr detectors show expected performance, a few detectors have high-energy tails on their photopeaks which are caused by nonflat tails on anode waveforms. The properties of these anode tails are studied and the generation of extra electrons by the movement of holes is proposed to explain the observations. The detector is operated in reverse bias (with holes drifting toward the pixelated electrode) to help confirm these observations and a mechanism for correcting preamplifier decay from long collection time digital waveforms is developed and used in the analysis.
Electrode pixelation of CdZnTe gamma-ray spectrometers has historically led to extraordinary energy resolutions for room-temperature operation and has enabled solid-state single-crystal Compton ...imaging. In this work, pixelated alternative room-temperature semiconductors, especially TlBr, were tested as gamma-ray spectrometers, and digital processing techniques were developed to improve their performance.Pixel ambipolar (electron and hole) sensitivity was observed in TlBr, CdZnTeSe, and CsPbBr3. The effects on traditional depth-reconstruction techniques were studied, and a technique to extract near-pixel position from the pixel waveform shape caused by ambipolar signals was devised. The new technique was implemented on TlBr spectrometers and used to perform an additional energy calibration, improving energy resolutions. This new technique may be used to probe charge transport properties on small length scales, and the improvement in resolution increases the viability of new ambipolar-sensitive spectrometers.Several anomalies such as transient leakage currents, transient bulk electron lifetimes, and transient cathode-localized Auger recombination were observed in TlBr. Some of these anomalies necessitated an increase in trigger thresholds, raising the fraction of single-pixel events experiencing incomplete charge collection. Methods to identify and remove these events were developed accounting for ambipolar signals and applied to TlBr spectrometers, improving photofractions. These methods can be applied to other ambipolar-sensitive spectrometers, increasing their viability.The additional energy calibration and the methods of reducing incomplete charge collection were applied to the best recent 11×11-pixel (22×22×5 mm3) TlBr detector, which improved from 4% uncalibrated to between 1.4% and 2.1% FWHM at 662 keV, dependent on the fraction of the active volume used, and improved the photofraction from 15% to 30%.
Thallium-bromide (TlBr) is a viable alternative to CZT for room-temperature gamma ray spectroscopy because of its high atomic number, high density, and wide band-gap. Sub-1% FWHM energy resolution at ...662 keV has been achieved on 5 mm thick pixelated devices, however, these results are mostly limited to stable operation at -20°C. During room-temperature operation, the devices degrade and fail, a phenomenon known as polarization. Polarization is likely caused by bulk-to-contact interactions facilitated by ionic conduction. In 2008, Hitomi et al. found that room-temperature lifetime could be extended by applying Tl electrodes. In this work we verify stable room-temperature performance of a 4.1 mm thick pixelated TlBr detector with Tl electrodes. Energy resolution, mobility-lifetime product, and resistivity are characterized and presented. Resolutions of 1.6% and 1.2% FWHM are achieved for all depths and cathode-side events only, respectively. A very high electron mobility-lifetime product is calculated: 3.1±0.2 ·10-2 cm2/V.
Path Forward for Biofuels and Biomaterials Ragauskas, A.J; Williams, C.K; Davison, B.H ...
Science (American Association for the Advancement of Science),
01/2006, Letnik:
311, Številka:
5760
Journal Article
Recenzirano
Biomass represents an abundant carbon-neutral renewable resource for the production of bioenergy and biomaterials, and its enhanced use would address several societal needs. Advances in genetics, ...biotechnology, process chemistry, and engineering are leading to a new manufacturing concept for converting renewable biomass to valuable fuels and products, generally referred to as the biorefinery. The integration of agroenergy crops and biorefinery manufacturing technologies offers the potential for the development of sustainable biopower and biomaterials that will lead to a new manufacturing paradigm.
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Background: Older adults with acute myeloid leukemia (AML) have identified home time (HT) as a critical outcome influencing their treatment selection. However, few studies have characterized HT ...in this disease setting. Methods: We conducted a retrospective, observational study of adults age ≥60 diagnosed with AML from 2015 to 2020 at University of North Carolina Health. First-line therapy was classified by intensity: low (hypomethylating agent HMA), intermediate (HMA+Venetoclax), and high (anthracycline-based). The primary outcome was cumulative HT days from time of diagnosis. A day was defined as HT if an individual was not hospitalized and did not utilize emergency department services or ambulatory oncology clinics. Secondary outcomes were proportion of days at home (PDH) and overall survival (OS). Covariates included demographics and disease risk by ELN 2017 criteria. HT was evaluated via summary statistics with comparisons among treatment groups made via linear (for HT / PDH) or Cox proportional hazard (for OS) regression models adjusted for age & ELN risk. PDH was further adjusted for log of follow up time. Median OS was calculated via the Kaplan-Meier method. Results: 197 individuals were identified. Mean age was 71 (range 60-95), 79% were white, and 59% male. 38% received high-intensity therapy, 33% received low, and 29% intermediate. Mean age was lower in the high-intensity group (66 vs 74 in low, 75 in intermediate; Kruskal-Wallis p < 0.0001). Mean HT was 284 days, and median survival was 10.3 months (95% CI 8.4-12.7). Mean HT was greater in the high-intensity group at 409 days (CI 310-508) vs. 243 (158-328) in low and 169 (121-216) in the intermediate group (Table). The high-intensity group had greater median OS at 19.9 months vs. 8.8 (low) or 7.7 (intermediate) but a lower mean adjusted PDH (high: 0.60 vs. low: 0.73 vs. intermediate: 0.75; p < 0.0001). In adjusted models, these differences remained statistically significant. Mean HT, median OS, and mean adjusted PDH did not differ significantly between the low & intermediate groups. Conclusions: Older adults with AML spend a tremendous amount of time - roughly 40% of days - engaged in oncology care. Although receiving high-intensity therapy was associated with longer OS, increases in HT were more modest, indicating that much of the survival gains were spent engaged in care. Shared treatment decision-making should incorporate patient preferences for securing HT versus attempting to prolong survival.Table: see text
Abstract only
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Background: AML is a disease of older adults (median age 67 years). Although standard AML treatment is intravenous (IV) chemotherapy, availability of oral anti-cancer medications ...has increased , providing benefits and risks to patients. Patients prefer their convenience, absence of IV infusions, potential for fewer clinic visits, and increased subjective feeling of control over their disease. Poor adherence can increase toxicity risk and compromise treatment effectiveness. We aim to identify barriers to adherence to oral medications in patients with AML and proposed solutions for improvements. Methods: Following IRB approval, patients with AML and their caregivers were recruited to participate in focus groups. An experienced moderator conducted the groups using an interview guide developed by AML experts. Participants received gift cards for their participation. Sessions were digitally recorded, transcribed verbatim, and analyzed for thematic content using Dedoose qualitative software. Results: 11 patients (5 <65 years; 6 >65 years) and 4 caregivers participated in sessions lasting 60-75 minutes. Three central themes emerged: medication adherence challenges, managing an oral adherence plan, and strategies to improve oral adherence. Adherence challenges: number and size of pills, different directions, cost, availability, and side effects. An adherence plan was recommended: written schedules, take medications around meals, and use of pillboxes and alarms. Main sources of information: health care team and bottle directions. Recommendations for providing adherence assistance included better instructions, assistance with scheduling, making pills smaller, and consistency in packaging. Conclusions: Patients are an important source of insight into barriers and solutions to oral medication adherence. These responses were used to develop a survey to be administered to 100 patients with AML. Results will inform development of an intervention to improve oral medication adherence in the AML population.
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