Exploration of Coincidence Detection of Cascade Photons to Enhance Preclinical Multi-Radionuclide SPECT Imaging

We proposed a technique of coincidence detection of cascade photons (CDCP) to enhance preclinical SPECT imaging of therapeutic radionuclides emitting cascade photons, such as Lu-177, Ac-225, Ra-223, and In-111. We have carried out experimental studies to evaluate the proposed CDCP-SPECT imaging of low-activity radionuclides using a prototype coincidence detection system constructed with large-volume cadmium zinc telluride (CZT) imaging spectrometers and a pinhole collimator. With In-111 in experimental studies, the CDCP technique allows us to improve the signal-to-contamination in the projection (Projection-SCR) by ~53 times and reduce ~98% of the normalized contamination. Compared to traditional scatter correction, which achieves a Projection-SCR of 1.00, our CDCP method boosts it to 15.91, showing enhanced efficacy in reducing down-scattered contamination, especially at lower activities. The reconstructed images of a line source demonstrated the dramatic enhancement of the image quality with CDCP-SPECT compared to conventional and triple-energy-window-corrected SPECT data acquisition. We also introduced artificial energy blurring and Monte Carlo simulation to quantify the impact of detector performance, especially its energy resolution and timing resolution, on the enhancement through the CDCP technique. We have further demonstrated the benefits of the CDCP technique with simulation studies, which shows the potential of improving the signal-to-contamination ratio by 300 times with Ac-225, which emits cascade photons with a decay constant of ~0.1 ns. These results have demonstrated the potential of CDCP-enhanced SPECT for imaging a super-low level of therapeutic radionuclides in small animals.

Exploring the design and performance of a tellurium optical sensor utilizing a plasticizer-free polymer inclusion membrane

A highly responsive, discerning, and uncomplicated technique has been devised for immobilizing reagents onto a plasticizer-free optical sensor membrane, employing polymer inclusion membranes (PIMs). This procedural strategy relies on a physical immobilization approach, specifically encapsulation, resulting in the creation of an optical sensing membrane. The responsive PIM is composed of poly(vinyl chloride) (PVC) as the fundamental polymer, Aliquat 336 as an extractant, and 4-(4 -chlorobenzylideneimino)-3-methyl-5-mercapto-1,2,4-triazole (CBIMMT) as the reagent. The optimized sensor demonstrates a linear range of 6.00-156 ng/mL for Te(IV), along with detection and quantification limits of 1.75 and 5.60 ng/mL, respectively. The sensor response time is 3.0 min, confirming its reproducibility. Effective regeneration of the sensor is achieved using a 0.2 mol/L HCl solution. The sensor membrane's selectivity is evaluated against various interfering ions, underscoring minimal interference. The sensor membrane efficacy is demonstrated through successful applications in quantifying Te(IV) levels, including natural water, chalcogenides, milk, vegetables, and soil samples.

Kidney dynamic SPECT acquisition on a CZT swiveling-detector ring camera: an in vivo pilot study

BACKGROUND

Large field of view CZT SPECT cameras with a ring geometry are available for some years now. Thanks to their good sensitivity and high temporal resolution, general dynamic SPECT imaging may be performed more easily, without resorting to dedicated systems. To evaluate the dynamic SPECT imaging by such cameras, we have performed an in vivo pilot study to analyze the kidney function of a pig and compare the results to standard dynamic planar imaging by a conventional gamma camera.

METHODS

A 7-week-old (12 kg) female Landrace pig was injected with [99mTc]Tc-MAG3 and a 30 min dynamic SPECT acquisition of the kidneys was performed on a CZT ring camera. A fast SPECT/CT was acquired with the same camera immediately after the dynamic SPECT, without moving the pig, and used for attenuation correction and drawing regions of interest. The next day the same pig underwent a dynamic planar imaging of the kidneys by a conventional 2-head gamma camera. The dynamic SPECT acquisition was reconstructed using a MLEM algorithm with up to 20 iterations, with and without attenuation correction. Time-activity curves of the total counts of each kidney were extracted from 2D and 3D dynamic images. An adapted 2-compartment model was derived to fit the data points and extract physiological parameters. Comparison of these parameters was performed between the different reconstructions and acquisitions.

RESULTS

Time-activity curves were nicely fitted with the 2-compartment model taking into account the anesthesia and bladder filling. Kidney physiological parameters were found in agreement with literature values. Good agreement of these parameters was obtained for the right kidney between dynamic SPECT and planar imaging. Regional analysis of the kidneys can be performed in the case of the dynamic SPECT imaging and provided good agreement with the whole kidney results.

CONCLUSIONS

Dynamic SPECT imaging is feasible with CZT swiveling-detector ring cameras and provides results in agreement with dynamic planar imaging by conventional gamma cameras. Regional analysis of organs uptake and clearance becomes possible. Further studies are required regarding the optimization of acquisition and reconstruction parameters to improve image quality and enable absolute quantification.

Aspiration of thrombus for intermediate-risk subacute pulmonary embolism

Pulmonary embolism is the most common cardiovascular disease after myocardial infarction and stroke. Konstantinides (Eur Heart J 41(4):543-603, 2020) Current guidelines categorize patients with PE as being at low, intermediate, and high risk of early death, with the intermediate-risk group experiencing the greatest uncertainty regarding treatment recommendations. Rapid reduction of the thrombus load by thrombolysis significantly reduces symptoms and decreases mortality, but is accompanied by a high risk of bleeding. Meyer (N Engl J Med 370(15):1402-11, 2014) Mechanical thrombectomy (CDTE) have been proven safe and efficient, yet current ESC guidelines suggest the utilization of catheter interventions only for hypotensive patients with high bleeding risk, failed systemic thrombolysis, and cardiogenic shock or if a patient does not respond to conservative therapy Konstantinides (Eur Heart J 41(4):543-603, 2020). Here, we report a case of an intermediate-risk patient with pulmonary embolism who underwent thrombus aspiration and showed significant improvement in symptoms after treatment.

Molecularly imprinted ratiometric fluorescence sensor for visual detection of 17β-estradiol in milk: A generalized strategy toward imprinted ratiometric fluorescence construction

17β-Estradiol (E2) is the typical endocrine disruptor of steroidal estrogens and is widely used in animal husbandry and dairy processing. In the environment, even lower concentrations of E2 can cause endocrine dysfunction in organisms. Herein, we have developed a novel molecularly imprinted ratiometric fluorescent sensor based on SiO2-coated CdTe quantum dots (CdTe@SiO2) and 7-hydroxycoumarin with a post-imprint mixing strategy. The sensor selectively detected E2 in aqueous environments due to its two fluorescent signals with a self-correction function. The sensor has been successfully used for spiking a wide range of real water and milk samples. The results showed that the sensor exhibited good linearity over the concentration range 0.011-50 μg/L, obtaining satisfactory recoveries of 92.4-110.6% with precisions (RSD) < 2.5%. Moreover, this sensor obtained an ultra-low detection limit of 3.3 ng/L and a higher imprinting factor of 13.66. By using estriol (E3), as a supporting model, it was confirmed that a simple and economical ratiometric fluorescent construction strategy was provided for other hydrophobic substances.

Calibration of medical gamma cameras for estimation of internal contamination from137Cs

Calibration of 22 gamma camera units was performed at 15 hospitals in southern and western Sweden to estimate137Cs contamination in humans in a supine static geometry, with a new developed calibration protocol and phantom. The minimum detectable activities (MDAs) and the estimated committed effective doses (CEDs) were calculated for each calibration. Generic calibration factors were calculated for five predetermined groups based on the detector type and manufacturer. Group 1 and 2 included NaI-based gamma cameras from General Electrics (GEs) with a crystal thickness of 5/8'' and 3/8'' respectively. Group 3 and 4 included NaI-based gamma cameras from Siemens Healthineers with a crystal thickness of 3/8'', with a similar energy window as the GE NaI-based cameras and a dual window respectively. Group 5 included semiconductor-based gamma cameras from GE with a CdZnTe (CZT) detector. The generic calibration factors were 60.0 cps kBq-1, 52.3 cps kBq-1, 50.3 cps kBq-1, 53.2 cps kBq-1and 48.4 cps kBq-1for group 1, 2, 3, 4, and 5 respectively. The MDAs ranged between 169 and 1130 Bq for all groups, with measurement times of 1-10 min, corresponding to a CED of 4.77-77.6μSv. A dead time analysis was performed for group 1 and suggested a dead time of 3.17μs for137Cs measurements. The dead time analysis showed that a maximum count rate of 232 kcps could be measured in the calibration geometry, corresponding to a CED of 108-263 mSv. It has been shown that semiconductor-based gamma cameras with CZT detectors are feasible for estimating137Cs contamination. The generic calibration factors derived in this study can be used for gamma cameras of the same models in other hospitals, for measurements in the same measurement geometry. This will increase the measurement capability for estimating internal137Cs contamination in the recovery phase following radiological or nuclear events.

Edge-illumination spectral phase-contrast tomography

Following the rapid, but independent, diffusion of x-ray spectral and phase-contrast systems, this work demonstrates the first combination of spectral and phase-contrast computed tomography (CT) obtained by using the edge-illumination technique and a CdTe small-pixel (62μm) spectral detector. A theoretical model is introduced, starting from a standard attenuation-based spectral decomposition and leading to spectral phase-contrast material decomposition. Each step of the model is followed by quantification of accuracy and sensitivity on experimental data of a test phantom containing different solutions with known concentrations. An example of a micro CT application (20μm voxel size) on an iodine-perfusedex vivomurine model is reported. The work demonstrates that spectral-phase contrast combines the advantages of spectral imaging, i.e. high-Zmaterial discrimination capability, and phase-contrast imaging, i.e. soft tissue sensitivity, yielding simultaneously mass density maps of water, calcium, and iodine with an accuracy of 1.1%, 3.5%, and 1.9% (root mean square errors), respectively. Results also show a 9-fold increase in the signal-to-noise ratio of the water channel when compared to standard spectral decomposition. The application to the murine model revealed the potential of the technique in the simultaneous 3D visualization of soft tissue, bone, and vasculature. While being implemented by using a broad spectrum (pink beam) at a synchrotron radiation facility (Elettra, Trieste, Italy), the proposed experimental setup can be readily translated to compact laboratory systems including conventional x-ray tubes.

Feasibility of myocardial blood flow quantification to detect flow-limited coronary artery disease with a one-day rest/stress continuous rapid imaging protocol on cardiac-dedicated cadmium zinc telluride single photon emission computed tomography

BACKGROUND

It is clinically needed to explore a more efficient imaging protocol for single photon emission computed tomography (SPECT) myocardial blood flow (MBF) quantitation derived from cadmium zinc telluride (CZT) SPECT camera for the routine clinical utilization.

METHODS

One hundred and twenty patients with matched clinical characteristics and angiographic findings who completed one-day rest/stress SPECT imaging with either the intermittently sequential imaging (ISI) protocol (two dynamic and two electrocardiography (ECG)-gated scans) or the continuous rapid imaging (CRI) protocol (two dynamic/ECG-gated scans) were included. MBF quantitation adopted residual activity correction (RAC) to correct for rest residual activity (RRA) in the stress dynamic SPECT scan for the detection of flow-limited coronary artery disease.

RESULTS

The CRI protocol reduced about 6.2 times shorter than the ISI protocol (25.5 min vs 157.6 min), but slightly higher than the RRA (26.7% ± 3.6% vs 22.3% ± 4.9%). With RAC, both protocols demonstrated close stress MBF (2.18 ± 1.13 vs 2.05 ± 1.10, P > 0.05) and myocardial flow reserve (MFR) (2.42 ± 1.05 vs 2.48 ± 1.11, P > 0.05) to deliver comparable diagnostic performance (sensitivity = 82.1%-92.3%, specificity = 81.2%-91.2%). Myocardial perfusion and left ventricular function overall showed no significant difference (all P > 0.26).

CONCLUSION

One-day rest/stress SPECT with the CRI protocol and rest RAC is feasible to warrant the diagnostic performance of MBF quantitation with a shortened examination time and enhanced patient comfort. Further evaluation on the impact of extracardiac activity to regional MBF and perfusion pattern is required. Additional evaluation is needed in a patient population that is typical of those referred for SPECT MPI, including those with known or suspected coronary microvascular disease.

Monte-Carlo study of contrast-enhanced spectral mammography with cadmium telluride photon-counting x-ray detectors

BACKGROUND

Contrast-enhanced spectral mammography (CESM) with photon-counting x-ray detectors (PCDs) can be used to improve the classification of breast cancers as benign or malignant. Commercially-available PCD-based mammography systems use silicon-based PCDs. Cadmium-telluride (CdTe) PCDs may provide a practical advantage over silicon-based PCDs because they can be implemented as large-area detectors that are more easily adaptable to existing mammography systems.

PURPOSE

The purpose of this work is to optimize CESM implemented with CdTe PCDs and to investigate the influence of the number of energy bins, electronic noise level, pixel size, and anode material on image quality.

METHODS

We developed a Monte Carlo model of the energy-bin-dependent modulation transfer functions (MTFs) and noise power spectra, including spatioenergetic noise correlations. We validated model predictions using a CdTe PCD with analog charge summing for charge-sharing suppression. Using the ideal-observer detectability, we optimized CESM for the task of detecting a 7-mm-diameter iodine nodule embedded in a breast with 50% glandularity. We optimized the tube voltage, beam filtration, and the location of energy thresholds for 50 and 100- μ $\mu$ m pixels, tungsten and molybdenum anodes, and two electronic noise levels. One of the electronic noise levels was that of the experimental system; the other was half that of the experimental system. Optimization was performed for CdTe PCDs with two or three energy bins. We also estimated the impact of anatomic noise due to background parenchymal enhancement and computed the minimum detectable iodine area density in the presence of quantum and anatomic noise.

RESULTS

Model predictions of the MTFs and noise power spectra agreed well with experiment. For optimized systems, adding a third energy bin increased quantum noise levels and reduced detectability by ∼55% compared to two-bin approaches that simply suppress contrast between fibroglandular and adipose tissue. Decreasing the electronic noise standard deviation from 3.4 to 1.7 keV increased iodine detectability by ∼5% and ∼30% for two-bin imaging and three-bin imaging, respectively. After optimizing for tube voltage, beam filtration, and the location of energy thresholds, there was ∼a 3% difference in iodine detectability between molybdenum and tungsten anodes for two-bin imaging, but for three-bin imaging, molybdenum anodes provided up to 14% increase in detectability relative to tungsten anodes. Anatomic noise decreased iodine detectability by 15% to 40%, with greater impact for lower electronic noise settings and larger pixel sizes.

CONCLUSIONS

For CESM implemented with CdTe PCDs, (1) quantitatively-accurate three-material decompositions using three energy bins are associated with substantial increases in quantum noise relative to two-energy-bin approaches that simply suppress contrast between fibroglandular and adipose tissues; (2) tungsten and molybdenum anodes can provide nearly equal iodine detectability for two-bin imaging, but molybdenum provides a modest detectability advantage for three-bin imaging provided that all other technique parameters are optimized; (3) reducing pixel sizes from 100 to 50  μ $\mu$ m can reduce detectability by up to 20% due to charge sharing; (4) anatomic noise due to background parenchymal enhancement is estimated to have a substantial impact on lesion visibility, reducing detectability by approximately 30%.

Ultra-fast whole-body bone tomoscintigraphies achieved with a high-sensitivity 360° CZT camera and a dedicated deep-learning noise reduction algorithm

This study aimed to determine whether the whole-body bone Single Photon Emission Computed Tomography (SPECT) recording times of around 10 min, routinely provided by a high-sensitivity 360° cadmium and zinc telluride (CZT) camera, can be further reduced by a deep-learning noise reduction (DLNR) algorithm.

METHODS

DLNR was applied on whole-body images recorded after the injection of 545 ± 33 MBq of [99mTc]Tc-HDP in 19 patients (14 with bone metastasis) and reconstructed with 100%, 90%, 80%, 70%, 60%, 50%, 40%, and 30% of the original SPECT recording times.

RESULTS

Irrespective of recording time, DLNR enhanced the contrast-to-noise ratios and slightly decreased the standardized uptake values of bone lesions. Except in one markedly obese patient, the quality of DLNR processed images remained good-to-excellent down to 60% of the recording time, corresponding to around 6 min SPECT-recording.

CONCLUSION

Ultra-fast SPECT recordings of 6 min can be achieved when DLNR is applied on whole-body bone 360° CZT-SPECT.

Occupational exposure to organotin substances: Development of a liquid chromatographic separation method for 11 organotin compounds in workplace air samples via HPLC-ICP-MS

Organotin compounds (OTCs) are widely regulated but rank among the most used organometallic compounds in various industrial sectors. They are significantly more toxic than inorganic tin compounds. At workplaces, OTCs can be released as vapors or dust particles and can be absorbed by inhalation or skin contact. Occupational exposure thus represents a great risk for the absorption of OTCs for employees. Methods for OTCs speciation in workplace air monitoring currently do not exist. This study describes the development of a separation method for eleven in Germany regulated OTCs via HPLC-ICP-MS. The method allows a near baseline separation of MMT, MBT, MOT, MPhT, DMT, DBT, DPhT, TMT, TBT, TPhT and TTMT within 22 min on a C18 column and a ternary solvent and flow rate gradient using methanol, acetonitrile, and ultrapure water + 6% (v/v) acetic acid + 0.17% (m/v) α-tropolone. Ten analytes show linearity in the working range of 10 - 100 µg OTCs/L with R² > 0.999. Due to its high volatility the analyte TTMT showed a quadratic relationship between concentration and signal intensity with R² = 0.9998. The determination of the instrumental limits resulted in detection limits between 0.14 and 0.57 µg Sn/L and limits of quantification between 0.49 and 1.97 µg Sn/L. Over the course of this study thermal instability and cross reactivity of OTC in solution became apparent. Formation of two reaction products in mixed OTCs solutions have been observed. These effects will further be examined within development of appropriate sampling and sample preparation for workplace air to provide a suitable method for the determination of OTCs at workplaces according to normative references.

Sulfur vacancy defects mediated CdZnTeS@BC heterojunction: Artificial intelligence-assisted self-enhanced electrochemiluminescence molecularly imprinted sensing of CTC

Environmental pollution caused by tetracycline antibiotics is a major concern of global public health. Here, a novel and portable molecularly imprinted electrochemiluminescence (MIECL) sensor based on smartphones for highly sensitive detection of chlortetracycline (CTC) has been successfully established. The high-performance ECL emitter of biomass carbon (BC) encapsulated CdZnTeS (CdZnTeS@BC) was successfully synthesized by hydrothermal. The enhanced ECL performance was ascribed to the introduction of the BC and increased the overall electrical conductivity of the nanoemitter, as well as increased the number of sulfur vacancies and doping on the surface of the emitter based on density functional theory calculations. An aniline-CTC molecular imprinted polymer was synthesized on the surface of the CdZnTeS@BC modified electrode by in-situ electropolymerization. The decrease in MIECL signal was attributed to the increase in impedance effect. The MIECL nanoplatform enabled a wide linear relationship in the range of 0.05-100 μmol/L with a detection limit of 0.029 μmol/L for spectrometer sensors. Interestingly, the light emitted during the MIECL reaction can be captured by a smartphone. Thus, machine learning was used to screen the photos that were taken, and color analysis was carried out on the screened photos by self-developed software, thus achieving a portable, convenient, and intelligent sensing mode. Finally, the sensor obtains satisfactory results in the detection of actual samples, with no significant differences from those of liquid chromatography.

Smartphone-assisted colorimetric dual-mode sensing system based on europium-doped metal-organic frameworks for rapid on-site visual detection of Fe3+ and doxycycline

Exploring a rapid, sensitive, low-cost, in-situ intelligent monitoring multi-target fluorescence detection platform is important for food safety and environmental monitoring. A dual-mode ratiometric fluorescence sensing system integrated with a smartphone based on a luminescent metal-organic framework (NH2-MIL-53) and CdTe/Eu was developed for visual, in-situ analysis of Fe3+ and doxycycline (DOX) in this paper. Interestingly, with increasing Fe3+ concentration, the fluorescence sensing system exhibits dual-emission with CdTe QDs at 540 nM as the response signal and NH2-MIL-53 at 438 nm as the reference signal, resulting in a significant color shift of fluorescence color from blue-green to blue, with a linear range of 5--1550 nM and a detection limit of 1.08 nM. In the presence of DOX, the blue fluorescence of NH2-MIL-53 and the green fluorescence of CdTe QDs were quenched respectively by the internal filtering effect and the photoelectron transfer effect. While DOX enhances the red fluorescence of Eu3+ by the antenna effect, forming a triple-emission fluorescence sensor. The visual color of this fluorescent sensor shifted from blue green to grey to pink-white to pink to fuchsia to red as the DOX concentration increased with a detection limit of 0.11 nM. Furthermore, the developed intelligent sensing platform achieved real-time in-situ detection of Fe3+ and DOX with detection limit of 1.47 nM and 6.43 nM, respectively. The platform was applied to detection actual samples with satisfactory results, which proved a promising application for real-time on-site food safety monitoring and human health monitoring.

Antibacterial Activity of CdTe/ZnS Quantum Dot-β Lactum Antibiotic Conjugates

β-Lactum antibiotics are broad class of antibiotics which kills bacteria by inhibiting the formation of peptidoglycan that constitutes the bacterial cell wall. The resistance that develops in bacteria for antibiotics led the scientific world to think about the future aspects for modifying the way through which antibiotics are acted on the bacteria and become lethal for them. In this consequence, the potential of latest marketed antibiotics e.g. Amoxiciline (I), ceftazidim (II) have been evaluated after being conjugated with quantum dots. The surface of quantum dots has been conjugated with antibiotics by carbodiimide coupling with the help of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) as conjugating agent between antibiotic and functionalized quantum dots. The antibacterial properties of QD-conjugated antibiotics have been determined by disc diffusion assay. The potency of QD-conjugated antibiotics has been estimated by determining their MIC50 for the selected strain of Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Minimum inhibitory concentration study, minimum bactericidal concentration and growth pattern analysis revealed that QD-antibiotic conjugates showed slightly more prospective than pure native antibiotics against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria.

Highly sensitive quantitative detection of glycans on exosomes in renal disease serums using fluorescence signal amplification strategies

Exosomal glycoproteins play a significant role in many physiological and pathological processes. However, the detection of exosome surface glycans is currently challenged by the complexity of biological samples or the sensitivity of the methods. Herein, we prepared a novel fluorescent probe of biotin-functionalized nanocrystals (denoted as CdTe@cys-biotin) and applied it for the first time for the detection of the expression of exosomal surface glycans using a fluorescence amplification strategy. First, the dual affinity of TiO2 and CD63 aptamers of Fe3O4@TiO2-CD63 was utilized to rapidly and efficiently capture exosomes within 25 min. In this design, interference from other vesicles and soluble impurities can be avoided due to the dual recognition strategy. The chemical oxidation of NaIO4 oxidized the hydroxyl sites of exosomal surface glycans to aldehydes, which were then labeled with aniline-catalyzed biotin hydrazide. Using the high affinity between streptavidin and biotin, streptavidin-FITC and probes were successively anchored to the glycans on the exosomes. The fluorescent probe achieved the dual function of specific recognition and fluorescent labeling by modifying biotin on the surface of nanocrystals. This method showed excellent specificity and sensitivity for exosomes at concentrations ranging from 3.30 × 102 to 3.30 × 106 particles/mL, with a detection limit of 121.48 particles/mL. The fluorescent probe not only quantified exosomal surface glycans but also distinguished with high accuracy between serum exosomes from normal individuals and patients with kidney disease. In general, this method provides a powerful platform for sensitive detection of exosomes in cancer diagnosis.

Unlocking the key role of bentonite fungal isolates in tellurium and selenium bioremediation and biorecovery: Implications in the safety of radioactive waste disposal

Research on eco-friendly bioremediation strategies for mitigating the environmental impact of toxic metals has gained attention in the last years. Among all promising solutions, bentonite clays, to be used as artificial barriers to isolate radioactive wastes within the deep geological repository (DGR) concept, have emerged as effective reservoir of microorganisms with remarkable bioremediation potential. The present study aims to investigate the impact of bentonite fungi in the speciation and mobility of selenium (Se) and tellurium (Te), as natural analogues 79Se and 132Te present in radioactive waste, to screen for those strains with bioremediation potential within the context of DGR. For this purpose, a multidisciplinary approach combining microbiology, biochemistry, and microscopy was performed. Notably, Aspergillus sp. 3A demonstrated a high tolerance to Te(IV) and Se(IV), as evidenced by minimal inhibitory concentrations of >16 and >32 mM, respectively, along with high tolerance indexes. The high metalloid tolerance of Aspergillus sp. 3A is mediated by its capability to reduce these mobile and toxic elements to their elemental less soluble forms [Te(0) and Se(0)], forming nanostructures of various morphologies. Advanced electron microscopy techniques revealed intracellular Te(0) manifesting as amorphous needle-like nanoparticles and extracellular Te(0) forming substantial microspheres and irregular accumulations, characterized by a trigonal crystalline phase. Similarly, Se(0) exhibited a diverse array of morphologies, including hexagonal, irregular, and needle-shaped structures, accompanied by a monoclinic crystalline phase. The formation of less mobile Te(0) and Se(0) nanostructures through novel and environmentally friendly processes by Aspergillus sp. 3A suggests it would be an excellent candidate for bioremediation in contaminated environments, such as the vicinity of deep geological repositories. It moreover holds immense potential for the recovery and synthesis of Te and Se nanostructures for use in numerous biotechnological and biomedical applications.

Energy spectrum measurement of scattered X-rays during IVR procedure

With the increase of the number of interventional radiology (IVR) procedures, the occupational exposure of operators and medical staff has attracted keen attention. The energy of scattered radiation in medical clinical sites is important for estimating the biological effects of occupational exposure. Recent years have seen many reports on the dose of scattered radiation by IVR, but few on the energy spectrum. In this study, the energy spectrum of scattered X-rays was measured by using a cadmium telluride (CdTe) semiconductor detector during IVR on several neurosurgical and cardiovascular cases. The cumulated spectra in each case were compared. The spectra showed little changes among neurosurgical cases and relatively large changes among cardiovascular cases. This was assumed to be due to the change of X-ray tube voltage and tube angle was larger in cardiovascular cases. The resulting energy spectra will be essential for the assessment of detailed biological effects of occupational exposure.

Bacterially synthesized superfine tellurium nanoneedles as an antibacterial and solar-thermal still for efficient purification of polluted water

Bacterial biosynthesis of nanomaterials has several advantages (e.g., reduced energy inputs, lower cost, negligible environmental pollution) compared with traditional approaches. Various nanomaterials have been produced by bacteria. However, reports on using the bacterial biosynthesis of nanomaterials for applications with solar-thermal agents are scarce due to their narrow optical absorption. Herein, for the first time, we proposed a bacterial biosynthesis of broad-absorbing tellurium nanoneedles and demonstrated their effectiveness for solar-thermal evaporation and antibacterial applications. By simple biosynthesis within bacteria (Shewanella oneidensis MR-1), tellurium nanoneedles achieved a superfine configuration with a length-to-diameter ratio of nearly 20 and broad-spectrum absorbance. After integrating tellurium nanoneedles into a porous polyvinyl-alcohol scaffold, a solar-thermal still named TSAS-3 realized a high evaporation rate of 2.25 kg m-2 h-1 and solar-thermal conversion efficiency of 81% upon 1-Sun illumination. Based on these unique properties, the scaffold displayed good performances in seawater desalination, multiple wastewater treatment, and antibacterial applications. This work provides a simple and feasible strategy for the use of microbial-synthesized nanomaterials in solar-driven water purification and antibacterial applications.

Simple dual-readout immunosensor based on phosphate-triggered and potassium permanganate for visual detection of fenitrothion

Multicolor-based visual immunosensor is a promising tool for rapid analysis without the use of bulky instruments. Herein, an anti-fenitrothion nanobody-alkaline phosphatase fusion protein (VHHjd8-ALP) was employed to develop a multicolor visual immunosensor (MVIS) and a ratiometric fluorescence MVIS (RFMVIS, respectively). After one-step competitive immunoassay, the VHHjd8-ALP bound to microplate catalyzed phenyl phosphate disodium salt (ArP) into phenol. Under high alkaline condition (pH 12), the phenol reduced KMnO4 to intermediate (K2MnO4) and further to MnO2 in alkaline condition (pH 12), accompanied by a visible color transition of purple-green-yellow, which can be used for semiquantitative visual analysis or qualitative detection by measuring RGB value. RFMVIS was proposed on the basis of MVIS to further improve sensitivity. The CdTe quantum dot and fluorescein were used as signal probes to develop the fluorescent immunosensor. The CdTe dots with red emission (644 nm) was quenched by oxidation of KMnO4, whereas the fluorescein with green emission (520 nm) remained constant, accompanied by a fluorescent color transition of green-yellow-red. By measuring the ratio of the fluorescence intensity (I644/I520), the ratiometric fluorescence immunosensor was developed for qualitative analysis. The two visual immunosensors were sensitive and simple, and they showed good accuracy and practicability in the recovery test, thus are ideal tools for rapid screening.

A simulation of a high-resolution cadmium zinc telluride positron emission tomography system

BACKGROUND

A CZT (cadmium zinc telluride) PET (positron emission tomography) system is being developed at Stanford University. CZT has the promise of outperforming scintillator-based systems in energy and spatial resolution but has relatively poor coincidence timing resolution.

PURPOSE

To supplement GATE (GEANT 4 Application for Emission Tomography) simulations with charge transport and electronics modeling for a high-resolution CZT PET system.

METHODS

A conventional GATE simulation was supplemented with electron-hole transport modeling and experimentally measured single detector energy resolution to improve the system-level understanding of a CZT high-resolution PET system in development at Stanford University. The modeling used GATE hits data and applied charge transport in the crystal and RC-CR processing of the simulated signals to model the electronics, including leading-edge discriminators and peak pick-off. Depth correction was also performed on the simulation data. Experimentally acquired data were used to determine energy resolution parameters and were compared to simulation data.

RESULTS

The distributions of the coincidence timing, anode energy, and cathode energy are consistent with experimental data. Numerically, the simulation achieved 153 ns FWHM coincidence time resolution (CTR), which is of the same order of magnitude as the raw 210 ns CTR previously found experimentally. Further, the anode energy resolution was found to be 5.9% FWHM (full width at half maximum) at 511 keV in the simulation, which is between the experimental value found for a single crystal of 3% and the value found for the dual-panel setup of 8.02%, after depth correction.

CONCLUSIONS

Developing this advanced simulation improves upon the limitations of GATE for modeling semiconductor PET systems and provides a means for deeper analysis of the coincidence timing resolution and other complementary electron-hole dependent system parameters.

In situ, synthesis of chitosan fabricated tellurium nanoparticles for improved antimicrobial and anticancer applications

The emergence of antibiotic resistance has had a severe impact on human health and economic burdens, drawing attention to the development of novel antimicrobial therapies. Polymer-metal composites have shown evidence of therapeutic applications by exerting antimicrobial effects and delivering these antimicrobials with biocompatibility. Therefore, this study prepared and characterized chitosan (CS)-fabricated tellurium nanoparticles (Te NPs) for enhanced antimicrobial, antioxidant, and cytotoxicity applications. The CS-Te NPs were spherical, polydisperse, and distributed within the CS matrix with an average size of 37.48 ± 14.56 nm, as confirmed by TEM analysis. CS-Te NPs exhibited positive zeta potential in neutral (pH 7.0: 7.90 ± 1.86 mV) and acidic environment. XRD analysis confirmed the crystalline nature of CS-Te NPs, and these nanoparticles exhibited good thermal and less porosity. A higher release of Te ions occurred from CS-Te NPs at an acidic pH. Further, CS-Te NPs displayed stronger antibacterial and antibiofilm activity against E. coli and S. enterica. Furthermore, CS-Te NPs exhibited significant free radical scavenging activity against ABTS and DPPH free radicals. Moreover, these nanoparticles demonstrated cytotoxicity against cancerous cells (A549 and PC3 cells) when compared to normal cells (NIH3T3 cells). Therefore, this study suggests that CS-Te NPs could serve as a substantial therapeutic agent.

Simultaneous detection of AFB1 and aflD gene by "Y" shaped aptamer fluorescent biosensor based on double quantum dots

The developed method for simultaneous detection of aflatoxin B1 (AFB1) and aflD genes can effectively monitor from the source and reduce the safety problems and economic losses caused by the production of aflatoxin, which can be of great significance for food safety regulations. In this paper, we constructed a sensitive and convenient fluorescent biosensor to detect AFB1 and aflD genes simultaneously based on fluorescence resonance energy transfer (FRET) between quantum dots (QDs) and a black hole quenching agent. A stable "Y" shaped aptasensor was employed as the detection platform and a double quantum dot labeled DNA fragment was utilized to be the sensing element in this work. When the targets of AFB1 and aflD genes were presented in the solution, the aptamer in the "Y" shaped probe is specifically recognized by the target. At this time, both Si-carbon quantum dots (Si-CDs) and CdTe QDs are far away from the BHQ1 and BHQ3 to recover the fluorescence. The linear range of the prepared fluorescence simultaneous detection method was as wide as 0.5-500 ng·mL-1 with detection lines of 0.64 ng·mL-1 for AFB1 and 0.5-500 nM with detection lines of 0.75 nM for aflD genes (3σ/k). This fabricated fluorescent biosensor was further validated in real rice flour and corn flour samples, which also achieved good results. The recoveries were calculated by comparing the known and found amounts of AFB1 which ranged from 88.4 to approximately 115.32% in the rice flour samples and 90.7 ~ 102.58% in the corn flour samples. The recoveries of aflD genes ranged from 84.32 to approximately 109.3% in the rice flour samples and 89.48 ~ 100.99% in the corn flour samples. Therefore, the proposed biosensor can significantly improve food safety and quality control through a simple, fast, and sensitive agricultural product monitoring and detection system.

Green synthesis of tellurium-doped SnO2 nanoparticles with sulfurized g-C3 N4 : Insights into methylene blue photodegradation and antibacterial capability

The construction of SnO2 nanoparticles (NPs), specifically Te-doped SnO2 NPs, using a simple and economical co-precipitation technique has been thoroughly described in this work. NH3 served as the reducing agent in this procedure, whilst polyethylene glycol served as the capping agent. The primary goals of our work were to investigate the physicochemical properties of the synthesized SnO2 NPs and assess their potential use as antibacterial agents and photocatalysts. Scanning electron microscopy-energy dispersive X-ray, ultraviolet light, Fourier transform infrared spectroscopy, X-ray diffraction (XRD), and other analytical techniques were used to thoroughly analyze the NPs. Based on the full width at half maximum of the most noticeable peaks in the XRD spectrum, the Debye-Scherrer equation was used to calculate the crystallite sizes, which indicated the presence of a single tetragonal SnO2 phase. Particularly noteworthy was the exceptional photocatalytic activity of graphene-assisted Te-doped SnO2 NPs, achieving an impressive decomposition efficiency of up to 98% in the photo-oxidation of methylene blue. Furthermore, our investigation delved into the antibacterial attributes of the synthesized SnO2 NPs against Escherichia coli and Staphylococcus aureus, demonstrating inhibitory effects on both bacteria strains. This suggests potential applications for these NPs in various environmental and medical contexts.

Doxorubicin-loaded PEG-CdTe QDs conjugated with anti-CXCR4 mAbs: a novel delivery system for extramedullary multiple myeloma treatment

Extramedullary multiple myeloma (EMM) is defined as the presence of plasma cells outside the bone marrow of multiple myeloma patients, and its prognosis is poor. High-dose chemotherapy with autologous stem cell transplantation, as a good option on early lines of therapy, has retained the survival benefit of youny EMM patients, but is intolerant for the majority of old patients because of drug cytotoxicity. To essentially address the intolerance above, we designed a CXCR4-PEG-CdTe-DOX (where CXCR4: chemokine receptor 4; PEG-CdTe: polyethylene glycol-modified cadmium telluride; DOX:doxorubicin) nanoplatform. First, CXCR4 is highly expressed in extramedullary plasma cells. Second, PEG-CdTe a drug carrier that controls drug release, can reduce adverse reactions, prolong drug (e.g, DOX) circulation time in the body, and form a targeting carrier after connecting antibodies. In vitro experiments showed CXCR4-PEG-CdTe-DOX facilitated intracellular drug accumulation through active CXCR4 targeting and released DOX into the microenvironment in a pH-controlled manner, enhancing the therapeutic efficacy and apoptosis rate of myeloma cells (U266). Therefore, targeted chemotherapy mediated by CXCR4-PEG-CdTe-DOX is a promising option for EMM treatment.

A novel multi-dimensional coal and gangue X-ray sorting algorithm based on CdZnTe photon counting detectors

BACKGROUND

The gangue content in coal seriously affects the calorific value produced by its combustion. In practical applications, gangue in coal needs to be completely separated. The pseudo-dual-energy X-ray method does not have high sorting accuracy.

OBJECTIVE

This study aims to propose a novel multi-dimensional coal and gangue X-ray sorting algorithm based on CdZnTe photon counting detectors to solve the problem of coal and gangue sorting by X-ray.

METHODS

This complete algorithm includes five steps: (1) Preferred energy bins, (2) transmittance sorting, (3) one-dimensional R-value sorting, (4) two-dimensional R-value sorting, and (5) three-dimensional R-value sorting. The output range of each step is determined by prior information from 65 groups of coal and gangue. An additional 110 groups of coal and gangue are employed experimentally to validate the algorithm's accuracy.

RESULTS

Compared with the 60% sorting accuracy of the Pseudo-dual-energy method, the new algorithm reached a sorting accuracy of 99%.

CONCLUSIONS

Study results demonstrate the superiority of this novel algorithm and its feasibility in practical applications. This novel algorithm can guide other two-substance X-ray sorting applications based on photon counting detectors.

First clinical experience of a ring-configured cadmium zinc telluride camera: A comparative study versus conventional gamma camera systems

BACKGROUND

A novel semiconductor cadmium zinc telluride (CZT) gamma camera system using a block sequential regularized expectation maximization (BSREM) reconstruction algorithm is now clinically available. Here we investigate how a multi-purpose ring-configurated CZT system can be safely applied in clinics and describe the initial optimization process.

METHOD

Seventy-six patients (bone-, cardiac- and lung scan) were scanned on a conventional gamma camera (planar and/or single-photon emission computed tomography [SPECT]/SPECT-CT) used in clinical routine and on the ring-configurated CZT camera Starguide (GE Healthcare). These data were used to validate and optimize the Starguide system for routine clinical use.

RESULTS

Comparable image quality for the Starguide system, to that of the conventional gamma camera, was achieved for bone scan (4 min/bed position [BP] using a relative difference prior [RDP] with gamma 2 and beta 0.4, along with 10 iterations and 10 subsets), cardiac scan (8 min [stress] and 3 min 20 s [rest] using median root prior [MRP] with beta 0.07 non attenuation corrected and 0.008 attenuation corrected and 50 interations and 10 subsets for both stress and rest) and lung scan (10 min [vent] and 5 min [perf] using RDP with gamma 0.5 and beta 0.03 [vent] and 0.02 [perf] and 20 interations and 10 subsets for both vent and perf).

CONCLUSIONS

It was possible to transition from a conventional gamma camera to the Starguide system as part of the clinical routine, with acceptable image quality. Images from the Starguide system were deemed to be at least as good as those from a conventional gamma camera.

Diagnostic performance of a novel deep learning attenuation correction software for MPI using a cardio dedicated CZT camera. Experience in the clinical practice

PURPOSE

To evaluate the diagnostic performance of a novel deep learning attenuation correction software (DLACS) for myocardial perfusion imaging (MPI) using a cadmium-zinc-telluride (CZT) cardio dedicated camera with invasive coronary angiography (ICA) correlation for the diagnosis of coronary artery disease (CAD) in a high-risk population.

METHODS

Retrospective study of 300 patients (196 males [65%], mean age 68 years) from September 2014 to October 2019 undergoing MPI, followed by ICA and evaluated by means of quantitative angiography software, within six months after the MPI. The mean pre-test probability score for coronary disease according to the European Society of Cardiology criteria was 37% for the whole cohort. The MPI was performed in a dedicated CZT cardio camera (D-SPECT Spectrum Dynamics) with a two-day protocol, according to the European Association of Nuclear Medicine guidelines. MPI was retrospectively evaluated with and without the DLACS.

RESULTS

The overall diagnostic accuracy of MPI without DLACS to identify patients with any obstructive CAD at ICA was 87%, sensitivity 94%, specificity 57%, Positive Predictive Value 91% and Negative Predictive Value 64%. Using DLACS the overall diagnostic accuracy was 90%, sensitivity 91%, specificity 86%, Positive Predictive Value 97% and Negative Predictive Value 66%.

CONCLUSION

Use of the novel DLACS enhances performance of the MPI using the CZT D-SPECT camera and achieves improved results, especially avoiding artefacts and reducing the number of false positive results.

Empirical optimization of energy bin weights for compressing measurements with realistic photon counting x-ray detectors

BACKGROUND

Photon counting detectors (PCDs) provide higher spatial resolution, improved contrast-to-noise ratio (CNR), and energy discriminating capabilities. However, the greatly increased amount of projection data in photon counting computed tomography (PCCT) systems becomes challenging to transmit through the slip ring, process, and store.

PURPOSE

This study proposes and evaluates an empirical optimization algorithm to obtain optimal energy weights for energy bin data compression. This algorithm is universally applicable to spectral imaging tasks including 2 and 3 material decomposition (MD) tasks and virtual monoenergetic images (VMIs). This method is simple to implement while preserving spectral information for the full range of object thicknesses and is applicable to different PCDs, for example, silicon detectors and CdTe detectors.

METHODS

We used realistic detector energy response models to simulate the spectral response of different PCDs and an empirical calibration method to fit a semi-empirical forward model for each PCD. We numerically optimized the optimal energy weights by minimizing the average relative Cramér-Rao lower bound (CRLB) due to the energy-weighted bin compression, for MD and VMI tasks over a range of material area densityρ A , m ${\rho }_{A,m}$ (0-40 g/cm2 water, 0-2.16 g/cm2 calcium). We used Monte Carlo simulation of a step wedge phantom and an anthropomorphic head phantom to evaluate the performance of this energy bin compression method in the projection domain and image domain, respectively.

RESULTS

The results show that for 2 MD, the energy bin compression method can reduce PCCT data size by 75% and 60%, with an average variance penalty of less than 17% and 3% for silicon and CdTe detectors, respectively. For 3 MD tasks with a K-edge material (iodine), this method can reduce the data size by 62.5% and 40% with an average variance penalty of less than 12% and 13% for silicon and CdTe detectors, respectively.

CONCLUSIONS

We proposed an energy bin compression method that is broadly applicable to different PCCT systems and object sizes, with high data compression ratio and little loss of spectral information.

Toward establishing a qualifying autoclitic repertoire in children with autism spectrum disorder

Autoclitics are secondary verbal operants that are controlled by a feature of the conditions that occasion or evoke a primary verbal operant such as a tact or mand. Qualifying autoclitics extend, negate, or assert a speaker's primary verbal response and modify the intensity or direction of the listener's behavior. Howard and Rice (1988) established autoclitics that indicated weak stimulus control (e.g., "like a [primary tact]") with four neurotypical preschool children. However, generalization to newly acquired tacts was limited. In Experiment 1, we addressed similar behavior as in Howard and Rice but with autistic children while using simultaneous teaching procedures, and we observed generalization across sets and with newly acquired tacts. In Experiment 2, we evaluated the effects of multiple-exemplar training on generalization of autoclitics across sets of naturalistic stimuli. Across participants, gradual increases in the frequency of autoclitics occurred with untaught stimuli after teaching with one or more sets.

Photoelectrochemical Enzyme Biosensor for Malate Using Quantum Dots on Indium Tin Oxide/Plastics as a Sensing Surface

A photoelectrochemical biosensor for malate was developed using an indium tin oxide (ITO) layer deposited on a poly(ethylene terephthalate) plastic sheet as a transparent electrode material for the immobilization of malate dehydrogenase together with CdTe quantum dots. Different approaches were compared for the construction of the bioactive layer; the highest response was achieved by depositing malate dehydrogenase together with CdTe nanoparticles and covering it with a Nafion/water (1:1) mixture. The amperometric signal of this biosensor was recorded during irradiation with a near-UV LED in the flow-through mode. The limit of detection was 0.28 mmol/L, which is adequate for analyzing malic acid levels in drinks such as white wines and fruit juices. The results confirm that the cheap ITO layer deposited on the plastic sheet after cutting into rectangular electrodes allows for the economic production of photoelectrochemical (bio)sensors. The combination of NAD+-dependent malate dehydrogenase with quantum dots was also compatible with such an ITO surface.

Experimental study on Compton camera for boron neutron capture therapy applications

Boron neutron capture therapy (BNCT) is a high-dose-intensive radiation therapy that has gained popularity due to advancements in accelerator neutron sources. To determine the dose for BNCT, it is necessary to know the difficult-to-determine boron concentration and neutron fluence. To estimate this dose, we propose a method of measuring the prompt γ-rays (PGs) from the boron neutron capture reaction (BNCR) using a Compton camera. We performed a fundamental experiment to verify basic imaging performance and the ability to discern the PGs from 511 keV annihilation γ-rays. A Si/CdTe Compton camera was used to image the BNCR and showed an energy peak of 478 keV PGs, separate from the annihilation γ-ray peak. The Compton camera could visualize the boron target with low neutron intensity and high boron concentration. This study experimentally confirms the ability of Si/CdTe Compton cameras to image BNCRs.

The ratiometric fluorescent sensor based on the mixture of CdTe quantum dots and graphene quantum dots for quantitative analysis of silver in drinks

Silver nanoparticles can be used in antibacterial packaging or disinfection. Research has shown that sugary fluid induces the leaching of silver nanoparticles into water, which may be harmful to humans. Single wavelength fluorescence analysis has been used for quantitative analysis of silver nanoparticles but suffers from low specificity and poor anti-interference ability. In this paper, a ratiometric fluorescence sensor system (GCS) was used for the detection of Ag+, which realized both visual detection and quantitative analysis of silver in drinks. The color changes of GCS with different concentrations of Ag+ are distinguishable and easy to analyze. There is also a good linear relationship between the concentrations of Ag+ and varieties of F424 nm/F570 nm, and the lowest detection limit reached 0.2266 nmol/L. This GCS shows good selectivity and recovery and could be used for the detection of Ag+ in drink samples.

Surface-enhanced fluorescence for lipopolysaccharide analysis based on shell-isolated nanoparticle

Lipopolysaccharide (LPS) as the component of cell membrane on gram-negative bacteria played a central role on inflammatory inducer to stimulate a multi-system host response. Herein, a surface-enhanced fluorescent (SEF) sensor was developed for LPS analysis based on shell-isolated nanoparticles (SHINs). The fluorescent signal of CdTe quantum dots (QDs) was amplified by silica shell-coated Au nanoparticles (Au NPs). The 3D finite-difference time-domain (3D-FDTD) simulation revealed that this enhancement was due to local electric field amplification. This method has a linear detection range of 0.1-20 μg/mL and a detection limit of 64 ng/mL for LPS. Furthermore, the developed method was successfully applied for LPS analysis in milk and human serum sample. The results indicated that the as-prepared sensor has significant potential for selective detection of LPS in biomedical diagnosis and food safety.

FF-1

Tellurium (Te) is a rare element within the chalcogen group, and its biogeochemical cycle has been studied extensively. Tellurite (Te(IV)) is the most soluble Te species and is highly toxic to organisms. Chemical or biological Te(IV) reduction to elemental tellurium (Te0) is generally considered an effective detoxification route for Te(IV)-containing wastewater. This study unveils a previously unnoticed Te0 oxidation process mediated by the manganese-oxidizing bacterium Bacillus sp. FF-1. This bacterium, which exhibits both Mn(II)-oxidizing and Te(IV)-reducing abilities, can produce manganese oxides (BioMnOx) and Te0 (BioTe0) when exposed to Mn(II) and Te(IV), respectively. When 5 mM Mn(II) was added after incubating 0.1 mM or 1 mM Te(IV) with strain FF-1 for 16 h, BioTe0 was certainly re-oxidized to Te(IV) by BioMnOx. Chemogenic and exogenous biogenic Te0 can also be oxidized by BioMnOx, although at different rates. This study highlights a new transformation process of tellurium species mediated by manganese-oxidizing bacteria, revealing that the environmental fate and ecological risks of Te0 need to be re-evaluated.

Accurate and efficient rapid acquisition early post-injection stress-first CZT SPECT myocardial perfusion imaging with tetrofosmin and attenuation correction

INTRODUCTION

Myocardial perfusion imaging (MPI) protocols have not changed significantly despite advances in instrumentation and software. We compared an early post-injection, stress-first SPECT protocol to standard delayed imaging.

METHODS

95 patients referred for SPECT MPI were imaged upright and supine on a Spectrum Dynamics D-SPECT CZT system with CT attenuation correction. Patients received injection of 99mTc tetrofosmin at peak of regadenoson stress and were imaged. Early post-stress (mean 17 ± 2 minutes) and Standard 1-h delay (mean 61 ± 13 min). Three blinded readers evaluated images for overall interpretation, perceived need for rest imaging, image quality, and reader confidence. Laboratory efficiency was also evaluated.

RESULTS

Blinded readers had the same response for the need for rest in 77.9% of studies. Studies also had the same interpretation in 89.5% of studies. Reader confidence was high (86.0% (Early) and 90.3% (Standard p = 0.52. Image quality was good or excellent in 87.4% Early vs 96.8% Standard (p = 0.09). Time between patient check-in and end of stress imaging was 104 ± (Standard) to 60 ± 18 minutes (Early) (p < 0.001).

CONCLUSION

Early post-injection stress-only imaging using CZT SPECT/CT appears promising with Tc-99m tetrofosmin with similar image quality, reader confidence, diagnosis, and need for a rest scan.

Nanomaterials-based aptasensors: An efficient detection tool for heavy-metal and metalloid ions in environmental and biological samples

In light of potential risks of heavy metal exposure, diverse aptasensors have been developed through the combination of aptamers with nanomaterials for the timely and efficient detection of metals in environmental and biological matrices. Aptamer-based sensors can benefit from multiple merits such as heightened sensitivity, facile production, uncomplicated operation, exceptional specificity, enhanced stability, low immunogenicity, and cost-effectiveness. This review highlights the detection capabilities of nanomaterial-based aptasensors for heavy-metal and metalloid ions based on their performance in terms of the basic quality assurance parameters (e.g., limit of detection, linear dynamic range, and response time). Out of covered studies, dendrimer/CdTe@CdS QDs-based ECL aptasensor was found as the most sensitive option with an LOD of 2.0 aM (atto-molar: 10-18 M) detection for Hg2+. The existing challenges in the nanomaterial-based aptasensors and their scientific solutions are also discussed.

Synthesis and performance study of PAM-g-PAA/PHEA and its application in purifying tellurium aerosol

In this study, grafted polymers (PAM-g-PAA/PHEA) with different grafting rates are prepared by solution method grafting polymer with polyacrylamide as the main chain, acrylic acid (AA) and 2-hydroxyethyl acrylate (HEA) as the modified monomers. Evidence of graft polymerization of AA and HEA on polyacrylamide side chains is obtained by FT-IR and 1HNMR. Scanning electron microscopy and thermogravimetric characterization further confirm the synthesis of grafted polymers. The properties of the grafting polymer are evaluated using grafting rate, viscosity, and surface tension measurements. The performance of polymer aqueous solution as an aerosol fixative for capturing and removing tellurium aerosol as a simulated polonium aerosol is examined. According to the results, grafting two monomers, acrylic acid, and 2-hydroxyethyl acrylate, effectively improve the cross-sectional structure of the polymer, increase the thermal stability of the polymer, and reduced the surface tension of the aqueous polymer solution to 42.47 mN/m. In addition, aerosol settling and fixation experiments showed that PAM-g-PAA/PHEA had a trapping and scavenging effect on tellurium aerosols with an immobilization rate of 94.86%, which revealed the immobilization mechanism of the immobilizer with tellurium aerosols.

Signal Modulation of Organic Photoelectrochemical Transistor by a Z-Scheme Photocathodic Gate: An Innovative Dual Amplification Strategy for Sensitive Aptasensing Application

Pursuing a more efficient signal amplification strategy is highly demanded for improving the performance of the promising cathodic photoelectrochemical (PEC) sensors. In this work, we present an extremely effective dual signal amplification strategy by the integration of a Z-scheme nanohybrids-based photocathode with the effective signal modulation of an organic photoelectrochemical transistor (OPECT) device. Specifically, photocathodic gate material of CdTe-BiOBr nanohybrids with a Z-scheme electron-transfer route was designed and synthesized for preliminary improvement of the activity of the photogate; afterward, signal modulation of the OPECT system by the photocathodic gate of CdTe-BiOBr was then accomplished for further signal amplification by 2 orders of magnitude. As a result, the output PEC signal of CdTe-BiOBr was enhanced by 17.5-fold as compared to BiOBr, and the channel current (IDS) of the OPECT device was 117-fold magnified than its gate current (IG) response. Exemplified by tetracycline (TC) as a model target and aptamer as the specific recognition element, a versatile cathodic aptasensing platform was constructed based on the proposed OPECT device. The introduced OPECT aptasensor merits advantages, including a good linear range (1.0 × 10-12 to 1.0 × 10-6 M), a low limit of detection (4.2 × 10-13 M), and superior sensitivity than the traditional PEC methods for TC detection, which represents a universal protocol for developing the innovative photocathodic OPECT sensing platform toward accurate analysis.

Dual-radionuclide in vivo imaging of micro-metastasis and lymph tract with submillimetre resolution

Multi-radionuclide in vivo imaging with submillimetre resolution can be a potent tool for biomedical research. While high-resolution radionuclide imaging faces challenges in sensitivity, multi-radionuclide imaging encounters difficulty due to radiation contamination, stemming from crosstalk between radionuclides and Compton scattering. Addressing these challenges simultaneously is imperative for multi-radionuclide high-resolution imaging. To tackle this, we developed a high-spatial-resolution and high-energy-resolution small animal single-photon emission computed tomography (SPECT) scanner, named CdTe-DSD SPECT-I. We first assessed the feasibility of multi-tracer SPECT imaging of submillimetre targets. Using the CdTe-DSD SPECT-I, we performed SPECT imaging of submillimetre zeolite spheres absorbed with 125I- and subsequently imaged 125I-accumulated spheroids of 200-400 µm in size within an hour, achieving clear and quantitative images. Furthermore, dual-radionuclide phantom imaging revealed a distinct image of the submillimetre sphere absorbed with 125I- immersed in a 99mTc-pertechnetate solution, and provided a fair quantification of each radionuclide. Lastly, in vivo imaging was conducted on a cancer-bearing mouse with lymph node micro-metastasis using dual-tracers. The results displayed dual-tracer images of lymph tract by 99mTc-phytic acid and the submillimetre metastatic lesion by 125I-, shown to align with the immunofluorescence image.

Photocatalytic degradation of tetracycline antibiotics by RGO-CdTe composite with enhanced apparent quantum efficiency

RGO-CdTe composite was synthesized using a straightforward, easy-to-realize, one-pot solvothermal technique. The synthesized composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Brunauer-Emmett-Teller method (BET), Raman spectra, UV-Vis absorption, and photoluminescence measurement. The RGO-CdTe composite exhibited 83.6% photocatalytic degradation efficiency for the aqueous tetracycline (TC) antibiotic solution and the apparent quantum yield (AQY) for the same was as high as 22.29% which is 2.63 times higher than that of CdTe. The scavenger investigation demonstrated that although hole acts as the leading active species, despite that, superoxide and hydroxyl radicals have also played crucial roles. The initial pH-dependent photocatalytic performance was measured. The zeta potential of the composite at different pH values was evaluated to establish the photocatalytic performance of the RGO-CdTe towards TC degradation at different pH. The recycling experiment depicts that only a 10% degradation performance declines after 5 times recycle use of the RGO-CdTe photocatalyst. An efficient photocurrent generation in RGO-CdTe thin film device has also been observed. Our study establishes as-synthesized composite of RGO-CdTe as a highly potential, and stable photocatalyst for the degradation of antibiotics from the polluted aqueous environment with a very good photoinduced charge generation efficiency in its solid phase.

Exploration of the pulse pileup effects in a clinical CdTe-based photon-counting computed tomography

BACKGROUND

High tube current generates a high flux of x-rays to photon counting detectors (PCDs) that can potentially result in the piling up of pulses formed by concurrent photons, which can cause count loss and energy resolution degradation.

PURPOSE

To evaluate the performance of clinical photon-counting CT (PCCT) systems in high flux, potentially influenced by pulse pileup effects, in terms of task-generic image quality metrics.

METHODS

A clinical phantom was scanned on a commercial PCCT scanner (NAEOTOM Alpha, Siemens) at 120 kV under fourteen different tube current levels (40-1000 mA) with a rotation time of 0.25 s and a pitch of 1. The dose levels corresponded to CTDIvol (32 cm phantom) of 0.79-19.8 mGy. CT sinograms were reconstructed using QIR-off mode (noniterative reconstruction algorithm), Br44 kernel, and a voxel size of0.4102 × 0.4102 × 3 mm 3 $0.4102 \times 0.4102 \times 3{\mathrm{\ mm}}^3$ . imQuest, an open-source MATLAB-based software package was used to calculate noise power spectrum (NPS), task transfer function (TTF), contrast-to-noise ratio (CNR), and CT number according to AAPM Task Group 233 metrology.

RESULTS

The 50% cut-off frequency of TTF (f50 ) remained mostly constant across all higher tube currents for all inserts, namely polyethylene, bone, air, and acrylic. Using the lowest two data points (40 and 80 mA), the expected relationship between noise magnitude and tube current was determined to be noise∝ $ \propto \ $ mA-0.47 . The measured noise magnitude were up to 11.1% higher than the expected value at the highest tube current. The average frequency of NPS (fav ) decreased from 0.32 to 0.29 mm-1 as tube current increased from 40 to 1000 mA. No considerable effects were observed in CT number measurement of any insert; however, CT numbers for air and bone changed almost monotonically as tube current increased. Absolute CNR increased monotonically for all inserts; however, the difference between measured and expected CNRs were approximately -6% to 12% across all tube currents.

CONCLUSIONS

Increasing tube currents did not affect the spatial resolution, but slightly affected the CT number and noise measurements of the clinical PCCT system. However, the effects were only considerable at clinically irrelevant tube currents used on a small 20-cm phantom. In general clinical practices, automatic exposure control techniques are used to decrease the variation of flux on the detector, which alleviates the chances of detector saturation due to high count rates. The observed effects could be due to pulse pileup, signal-dependent filtration of the system, or nonlinearities in the reconstruction algorithm. In conclusion, either the deadtime of the detector used in the photon-counting CT system is shorter such that count losses due to pulse pileup are negligible, or pulse pileup has inconsiderable effects on the image quality of clinical photon-counting CT systems in routine clinical practice due to possible corrections applied on the system.

A dual-mode method for detection of miRNA based on the photoluminescence and resonance light scattering

MicroRNAs (miRNAs) hold potential as useful biomarkers for early diagnosis and evaluation of diverse cancers, but their low abundance and short length make the detection of miRNAs face low sensitivity and accuracy. Herein, a photoluminescence (PL)-resonance light scattering (RLS) dual-mode method was developed for the sensitive and accurate detection of miRNA-141 using CdTe quantum dots (QDs) and Au nanoparticles. The presence of miRNA-141 induced PL quenching and RLS increasing. The limit of detection (LOD) was as low as 3.7 fM, and the miRNA-141 was detected linearly in a range from 10 fM to 10 nM. The dual signals generated no mutual interference and were detected using the same spectrophotometer, allowing for mutual validation to ensure the accuracy and reliability of the detection results. This study proposes valuable references for constructing dual-mode detection methods.

Artificial photosynthetic cells with biotic-abiotic hybrid energy modules for customized CO2 conversion

Programmable artificial photosynthetic cell is the ultimate goal for mimicking natural photosynthesis, offering tunable product selectivity via reductase selection toward device integration. However, this concept is limited by the capacity of regenerating the multiple cofactors that hold the key to various reductases. Here, we report the design of artificial photosynthetic cells using biotic-abiotic thylakoid-CdTe as hybrid energy modules. The rational integration of thylakoid with CdTe quantum dots substantially enhances the regeneration of bioactive NADPH, NADH and ATP cofactors without external supplements by promoting proton-coupled electron transfer. Particularly, this approach turns thylakoid highly active for NADH regeneration, providing a more versatile platform for programming artificial photosynthetic cells. Such artificial photosynthetic cells can be programmed by coupling with diverse reductases, such as formate dehydrogenase and remodeled nitrogenase for highly selective production of formate or methane, respectively. This work opens an avenue for customizing artificial photosynthetic cells toward multifarious demands for CO2 conversion.

Multifunctional light-controllable nanozyme enabled bimodal fluorometric/colorimetric sensing of mercury ions at ambient pH

Nanomaterials with enzyme-like catalytic features (nanozymes) find wide use in analytical sensing. Apart from catalytic characteristics, some other interesting functions coexist in the materials. How to combine these properties to design multifunctional nanozymes for new sensing strategy development is challenging. Besides, in nanozymes it is still a challenge to conveniently control the catalytic process, which also hinders their further applications in advanced biochemical analysis. To remove the above barriers, here we design a light-controllable multifunctional nanozyme, namely manganese-inserted cadmium telluride (Mn-CdTe) particles, that integrates oxidase-like activity with luminescence together, to achieve the fluorometric/colorimetric dual-mode detection of toxic mercury ions (Hg2+) at ambient pH. The Mn-CdTe exhibits a light-triggered oxidase-mimicking catalytic behavior to induce chromogenic reactions, thus enabling one to start or stop the catalytic progress easily via applying or withdrawing light irradiation. Meanwhile, the quantum dot material can exhibit bright photoluminescence, which provides the fluorometric channel to sense targets. When Hg2+ is introduced, it rapidly leans toward Mn-CdTe through electrostatic interaction and Te-Hg bonding and induces the aggregation of the latter. As a result, the luminescence of Mn-CdTe is dynamically quenched, and the masking of active sites in aggregated Mn-CdTe leads to the decrease of light-initiated oxidase-mimetic activity. According to this principle, a new fluorometric/colorimetric bimodal method was established for Hg2+ determination with excellent performance. A 3D-printed portable platform combining paper-based test strips and an App-equipped smartphone was further fabricated, making it possible to achieve in-field sensing of the analyte in various matrices.

A dual-model immobilization-free photoelectrochemical/visual colorimetric bioanalysis based on microemulsion self-assemblies mediated multifunctional signal amplification strategy

Herein, a novel silver ion-loaded gold microemulsion assemblies (Au/Ag+ MAs) mediated multifunctional signal amplification strategy was proposed to construct a sensitive immobilization-free photoelectrochemical (PEC)/colorimetric biosensor for carcinoembryonic antigen (CEA) detection. Through the sandwiched reaction among CEA, the CEA aptamer (DNA1) loaded on the Au nanoparticles (NPs) functionalized iron oxide (Fe3O4) nanospheres and another CEA aptamer (DNA2) immobilized on Au/Ag+ MAs, a complex is formed and acquired by magnetic separation. Then, Au/Ag+ MAs of the complex are disassembled into Au NPs and Ag+ ions driven by an acetone response, and the obtained demulsification solution is transferred to the cadmium sulfide/cadmium telluride (CdS/CdTe) photoactive composites modified electrode. Based on the multiple inhibition functions (blocking effect of oleylamine; energy transfer effect of Au NPs; and electron snatching effect of Ag+), the photocurrent of the electrode decreases obviously, resulting in the ultrasensitive detection of CEA (a detection limit of 16 fg mL-1). Interestingly, the ion-exchange reactions between CdS/CdTe composites and Ag+ ions generate silver sulfide/silver telluride (Ag2S/Ag2Te) composites, and a color change of composites can be distinguished directly, leading to a quick visual detection of CEA. Compared with the traditional single-modal assay for CEA, such dual-modal PEC/colorimetric assay is a more accurate and reliable due to different mechanisms and independent signal conversion. This work will offer a new perspective for the applications of various self-assemblies in PEC bioanalysis.

On the origin of diffuse intensities in fcc electron diffraction patterns

Interpreting diffuse intensities in electron diffraction patterns can be challenging in samples with high atomic-level complexity, as often is the case with multi-principal element alloys. For example, diffuse intensities in electron diffraction patterns from simple face-centred cubic (fcc) and related alloys have been attributed to short-range order1, medium-range order2 or a variety of different {111} planar defects, including thin twins3, thin hexagonal close-packed layers4, relrod spiking5 and incomplete ABC stacking6. Here we demonstrate that many of these diffuse intensities, including [Formula: see text]{422} and [Formula: see text]{311} in ⟨111⟩ and ⟨112⟩ selected area diffraction patterns, respectively, are due to reflections from higher-order Laue zones. We show similar features along many different zone axes in a wide range of simple fcc materials, including CdTe, pure Ni and pure Al. Using electron diffraction theory, we explain these intensities and show that our calculated intensities of projected higher-order Laue zone reflections as a function of deviation from their Bragg conditions match well with the observed intensities, proving that these intensities are universal in these fcc materials. Finally, we provide a framework for determining the nature and location of diffuse intensities that could indicate the presence of short-range order or medium-range order.