Fast Scanning Research Articles

Organic compounds as temperature calibrants for fast scanning calorimetry

Organic compounds can be used as temperature calibrants in fast scanning calorimetry. Their advantages include ease of surface cleaning of the calorimetric chip and good thermal contact with the chip surface. Among several compounds tested, benzoic acid was identified as a convenient and reliable calibrant for temperatures below approximately 130 °C. However, organic calibrants often exhibit unusual heating rate dependencies of the onset temperatures of melting. This phenomenon can be semi-quantitatively explained by considering different heat flows within the sensor. Notably, the thermal resistance between the heater and thermopile, often overlooked, introduces an additional time constant that can sometimes result in a negative apparent thermal lag. In addition, the onset temperatures are influenced by factors such as sample position, thickness, surface wetting, and spreading. These factors limit the accuracy of transition temperature determinations to approximately ±1 K below 130 °C and ±5 K up to 220 °C.

Ultra-fast Digital DPC Yielding High Spatio-temporal Resolution for Low-Dose Phase Characterization.

In the scanning transmission electron microscope, both phase imaging of beam-sensitive materials and characterization of a material's functional properties using in situ experiments are becoming more widely available. As the practicable scan speed of 4D-STEM detectors improves, so too does the temporal resolution achievable for both differential phase contrast (DPC) and ptychography. However, the read-out burden of pixelated detectors, and the size of the gigabyte to terabyte sized data sets, remain a challenge for both temporal resolution and their practical adoption. In this work, we combine ultra-fast scan coils and detector signal digitization to show that a high-fidelity DPC phase reconstruction can be achieved from an annular segmented detector. Unlike conventional analog data phase reconstructions from digitized DPC-segment images yield reliable data, even at the fastest scan speeds. Finally, dose fractionation by fast scanning and multi-framing allows for postprocess binning of frame streams to balance signal-to-noise ratio and temporal resolution for low-dose phase imaging for in situ experiments.

Clinical performance of deep learning-enhanced ultrafast whole-body scintigraphy in patients with suspected malignancy

BackgroundTo evaluate the clinical performance of two deep learning methods, one utilizing real clinical pairs and the other utilizing simulated datasets, in enhancing image quality for two-dimensional (2D) fast whole-body scintigraphy (WBS).MethodsA total of 83 patients with suspected bone metastasis were retrospectively enrolled. All patients underwent single-photon emission computed tomography (SPECT) WBS at speeds of 20 cm/min (1x), 40 cm/min (2x), and 60 cm/min (3x). Two deep learning models were developed to generate high-quality images from real and simulated fast scans, designated 2x-real and 3x-real (images from real fast data) and 2x-simu and 3x-simu (images from simulated fast data), respectively. A 5-point Likert scale was used to evaluate the image quality of each acquisition. Accuracy, sensitivity, specificity, and the area under the curve (AUC) were used to evaluate diagnostic efficacy. Learned perceptual image patch similarity (LPIPS) and the Fréchet inception distance (FID) were used to assess image quality. Additionally, the count-level consistency of WBS was compared between the two models.ResultsSubjective assessments revealed that the 1x images had the highest general image quality (Likert score: 4.40 ± 0.45). The 2x-real, 2x-simu and 3x-real, 3x-simu images demonstrated significantly better quality than the 2x and 3x images (Likert scores: 3.46 ± 0.47, 3.79 ± 0.55 vs. 2.92 ± 0.41, P < 0.0001; 2.69 ± 0.40, 2.61 ± 0.41 vs. 1.36 ± 0.51, P < 0.0001), respectively. Notably, the quality of the 2x-real images was inferior to that of the 2x-simu images (Likert scores: 3.46 ± 0.47 vs. 3.79 ± 0.55, P = 0.001). The diagnostic efficacy for the 2x-real and 2x-simu images was indistinguishable from that of the 1x images (accuracy: 81.2%, 80.7% vs. 84.3%; sensitivity: 77.27%, 77.27% vs. 87.18%; specificity: 87.18%, 84.63% vs. 87.18%. All P > 0.05), whereas the diagnostic efficacy for the 3x-real and 3x-simu was better than that for the 3x images (accuracy: 65.1%, 66.35% vs. 59.0%; sensitivity: 63.64%, 63.64% vs. 64.71%; specificity: 66.67%, 69.23% vs. 55.1%. All P < 0.05). Objectively, both the real and simulated models achieved significantly enhanced image quality from the accelerated scans in the 2x and 3x groups (FID: 0.15 ± 0.18, 0.18 ± 0.18 vs. 0.47 ± 0.34; 0.19 ± 0.23, 0.20 ± 0.22 vs. 0.98 ± 0.59. LPIPS: 0.17 ± 0.05, 0.16 ± 0.04 vs. 0.19 ± 0.05; 0.18 ± 0.05, 0.19 ± 0.05 vs. 0.23 ± 0.04. All P < 0.05). The count-level consistency with the 1x images was excellent for all four sets of model-generated images (P < 0.0001).ConclusionsUltrafast 2x speed (real and simulated) images achieved comparable diagnostic value to that of standardly acquired images, but the simulation algorithm does not necessarily reflect real data.

Combining Enhanced Resolving Power with Duty Cycle Improvements on a Multi-Reflecting Time-of-Flight Mass Spectrometer.

The combination of enhanced resolving power and improved duty cycle on a multireflecting time-of-flight mass spectrometer is described. Resolving power increases are achieved by extending the effective ion path length from 47 m to greater than 200 m. Path length increases are achieved through containment of ions within the analyzer for up to N = 5 passes using a pulsed deflection electrode. Resolving power was shown to increase from 220,000 to 402,000 (fwhm) at m/z 785 for N = 1 and N = 4 analyzer passes, respectively. Due to the timing of the pulsed deflection electrode, the approach is particularly suited to high resolution analysis over a targeted m/z range. Duty cycle enhancements are achieved for ions of the targeted m/z range via accumulation prior to orthogonal acceleration, providing signal improvements of 2 orders of magnitude. Achieving such high resolving powers at fast scan rates (30 Hz) can yield additional information such as fine isotope structure; when combined with ppb mass measurement accuracy, high confidence in analyte identification can be achieved. The technique is applied for N = 2 analyzer passes, demonstrating fine isotope structure for a typical UHPLC metabolite identification experiment at a 10 Hz acquisition rate. Additionally, mass spectrometry imaging data is acquired using DESI, demonstrating the improved image clarity achieved at >300,000 (fwhm).

Frontiers in artificial intelligence-directed light-sheet microscopy for uncovering biological phenomena and multi-organ imaging.

Light-sheet fluorescence microscopy (LSFM) introduces fast scanning of biological phenomena with deep photon penetration and minimal phototoxicity. This advancement represents a significant shift in 3-D imaging of large-scale biological tissues and 4-D (space + time) imaging of small live animals. The large data associated with LSFM requires efficient imaging acquisition and analysis with the use of artificial intelligence (AI)/machine learning (ML) algorithms. To this end, AI/ML-directed LSFM is an emerging area for multi-organ imaging and tumor diagnostics. This review will present the development of LSFM and highlight various LSFM configurations and designs for multi-scale imaging. Optical clearance techniques will be compared for effective reduction in light scattering and optimal deep-tissue imaging. This review will further depict a diverse range of research and translational applications, from small live organisms to multi-organ imaging to tumor diagnosis. In addition, this review will address AI/ML-directed imaging reconstruction, including the application of convolutional neural networks (CNNs) and generative adversarial networks (GANs). In summary, the advancements of LSFM have enabled effective and efficient post-imaging reconstruction and data analyses, underscoring LSFM's contribution to advancing fundamental and translational research.

Do We Need a Relaparotomy to Remove the Perihepatic Packs Used to Control Bleeding? Case Series

Introduction: Liver injuries, often resulting from trauma, present a significant challenge in surgical management. Perihepatic packing has emerged as a critical technique in controlling bleeding and stabilising patients with severe liver injuries. This study aims to evaluate the outcomes of perihepatic packing and removing packs without relaparotomy in a cohort of eleven patients treated over two years.Methods: We conducted a retrospective study of 11 patients with liver injuries identified at laparotomy at General Hospital Kuliyapitiya from May 2020 to June 2022. Excluded were patients who managed without packing. Data were collected from operating theatre records and medical charts, including age, sex, injury mechanism, vital signs, FAST scan results, intraoperative findings, estimated blood loss, blood transfused in the first 24 hours, associated injuries, liver complications, time to pack removal, and incidence of rebleeding.Perihepatic packing has been used for persistent hepatic haemorrhage post-suturing, unsaturable injuries, and hemodynamically unstable patients. Packs have been brought outside the abdomen through a separate incision and sutured to each other if multiple packs were used. A G28 intercostal tube has placed for drainage. Packs have been removed between 48 and 72 hours. The drain has kept for more than 48 hours post-removal to monitor rebleeding. In cases of uncontrollable haemorrhage during pack removal, plans included reopening and repacking if necessary.Results: The study included eleven patients aged 24 to 74 years, with three female patients. The causes of liver injuries were identified as follows: road traffic accidents (63.6%), assault (18.2%), stab injuries (9.1%), and falls from height (9.1%). Pre-operative ultrasound correctly identified liver injuries in 54.6% of patients. Intraoperative findings showed right liver lobe involvement in 63.6% of cases, bilobar involvement in 27.3%, and left lobe involvement in 9.1%. Additionally, 63.6% of patients had other organ injuries. The timing of pack removal was within 48 hours for seven patients (63.6%) and within 48-72 hours for the remaining patients. Drains were removed on the fifth day in 54.50% of patients and on the sixth day in the rest. There were no cases of rebleeding and post of complications were able to be managed conservatively. There was one death with sepsis and multi organ disfunction.Conclusion: Perihepatic packing is a valuable technique in the management of liver injuries, demonstrating high efficacy in controlling haemorrhage and low complication rates. Removal of the pack through the pre-placed incision avoids the relaparotomy and thereby reduces the second trauma to the patient. Further studies with larger cohorts are recommended to validate these findings.

Thermal and Thermomechanical Analysis of Amorphous Metals: A Compact Review

Metallic glasses are amorphous metals that are supercooled to a frozen, glassy state and lack long-range order, in contrast to conventional metal structures. The lack of a well-ordered structure largely contributes to the unique properties exhibited by these materials. However, their synthesis and processability are defined and thereby constrained by a plethora of thermal and mechanical parameters. Therefore, their broader utilization in the scientific field and particularly in the related industry is somewhat hindered by the limitations related to preparing them in higher amounts. This may be overcome by changing the approach of metal glass formation to a bottom-up approach by utilizing solid-state plasma techniques, such as spark plasma ablation. Another important aspect of amorphous metals, inherently related to their non-equilibrium metastable nature, is the necessity to understand their thermal transformations, which requires unconventional thermal analysis methods. Therefore, this minute review aims to highlight the most important conceptual parameters behind configuring and performing conventional and advanced thermal analysis techniques. The importance of calorimetry methods (differential and fast scanning calorimetry) for the determination of key thermal properties (critical cooling rate, glass-forming ability, heat capacity, relaxation, and rejuvenation) is underscored. Moreover, the contributions of thermomechanical analysis and in situ temperature-dependent structural analysis are also mentioned. Namely, all of the mentioned temperature-dependent mechanical and structural analyses may give rise to the discovery of new glass systems with low critical cooling rates.

Who Says You can't go FAST at Night? Use of a Novel Ultrasound-Capable Night Vision Device for Prehospital Medical Personnel to Identify Noncompressible Truncal Hemorrhage.

Early detection of abdominal hemorrhage via ultrasound has life-saving implications for military and civilian trauma. However, strict adherence to light discipline may prohibit the use of ultrasound devices in the deployed setting. Additionally, current night vision devices remain noncompatible with ultrasound technology. This study sought to assess an innovative night vision device with ultrasound capable picture-in-picture display via a intraabdominal hemorrhage model to identify noncompressible truncal hemorrhage in blackout conditions. 8 post mortem fetal porcine specimens were used and divided into 2 groups: intrabdominal hemorrhage (n = 4) vs no hemorrhage (n = 4). Intrabdominal hemorrhage was modeled via direct injection of 200mL of normal saline into the peritoneal cavity. Under blackout conditions, 5 participants performed a focused assessment with sonography for trauma (FAST) exam on each model using the prototype ultrasound-capable night vision device. Of the 40 FAST exams performed, 95% (N = 38) resulted in the correct identification of intraabdominal hemorrhage. Of the incorrectly identified exams, both were false positives resulting in a 100% sensitivity, 90% specificity, 91% positive predictive value, and a 100% negative predictive value. All participants noted the novel device was easy to use and provided superior visualization for performing FAST exams under blackout conditions. The ultrasound-enabled night vision prototype demonstrated promising results in identifying noncompressible truncal hemorrhage while maintaining strict light discipline in blackout conditions. Further research efforts should be directed at assessing the ability of providers to perform procedures in blackout conditions using the ultrasound-enabled prototype night vision device.

Development of an Aptamer-Modified Wearable Biosensor for Early Detection of Traumatic Brain Injuries

Traumatic brain injuries (TBI) can significantly alter brain function and present as a critical, potentially life-threatening condition necessitating prompt identification and ongoing monitoring. Categorized as mild, moderate, or severe, TBIs often manifest challenging post-injury symptoms. Despite scientific advancements, the methodologies for TBI identification, evaluation, and monitoring have remained largely unchanged for the past 50 years. To address this, our proposal focuses on creating an electrochemical biosensor for the early detection of glial fibrillary acidic protein (GFAP), a crucial biomarker associated with TBI. Our approach involves employing the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technique to develop a highly specific aptamer for GFAP detection. The biosensor will utilize aptamer-modified electrodes with a carbon-based substrate to enable continuous real-time detection of the target. By detecting GFAP, our biosensor aims to mitigate risks associated with injury-related damage, exposure to ionizing radiation, and healthcare expenses. Moreover, our proposed strategy seeks to advance our comprehension of GFAP release and its role in early TBIs, potentially paving the way for future in vivo studies. To enhance the biosensor's long-term stability, our design centers on a carbon-based nanomaterial substrate. Carbon-based nanomaterials have gained prominence in biosensor applications due to their diverse properties, including conductivity, chemical stability, mechanical strength, surface-to-volume ratio, biocompatibility, functionalization, and biodegradability. Our biosensor's advancement will employ electrochemical impedance spectroscopy (EIS), fast scan cyclic voltammetry (FSCV), and square wave voltammetry (SWV) for electrochemical testing. Electrochemistry offers numerous advantages over light-based detection methods, allowing for enhanced electrode surface modification to improve selectivity and flexibility. This adaptability positions our biosensor as an ideal candidate for wearable applications in field settings, capable of detecting a broad spectrum of molecules beyond oxidation or reduction reactions. The successful realization of these objectives will result in a GFAP-detecting biosensor. Our proposed experiments aim to bridge existing gaps by developing a novel device for non-invasively measuring biomarkers released through sweat, thereby contributing to innovative diagnostic approaches. Figure 1

All-Diamond Boron-Doped Microelectrodes for Neurochemical Sensing with Fast-Scan Cyclic Voltammetry.

Neurochemical sensing with implantable devices has gained remarkable attention over the last few decades. A promising area of this research is the progress of novel electrodes as electrochemical tools for neurotransmitter detection in the brain. The boron-doped diamond (BDD) electrode is one such candidate that previously has been reported for its excellent electrochemical properties, including a wide working potential, superior chemical inertness and mechanical stability, good biocompatibility and resistance to fouling. Meanwhile, limited research has been conducted on the BDD as a microelectrode for neurochemical detection. Our team has developed a freestanding, all diamond microelectrode consisting of a boron-doped polycrystalline diamond core, encapsulated in an insulating polycrystalline diamond shell, with a cleaved planar tip for electrochemical sensing. This all-diamond electrode is advantageous due to its - (1) batch fabrication using wafer technology that eliminates traditional hand fabrication errors and inconsistencies, (2) absence of metal-based wires, or foundations, to improve biocompatibility and flexibility, and (3) sp 3 carbon surface with resistance to biofouling, i.e. adsorption of proteins or unwanted molecules at the electrode surface in a biological environment that impedes overall electrode performance. Here, we provide findings on further in vitro testing and development of the freestanding boron-doped diamond microelectrode (BDDME) for neurotransmitter detection using fast scan cyclic voltammetry (FSCV). In this report, we elaborate on - 1) an updated fabrication scheme and work flow to generate all diamond BDDMEs, 2) slow scan cyclic voltammetry measurements of reference and target analytes to understand basic electrochemical behavior of the electrode, and 3) FSCV characterization of common neurotransmitters, and overall favorability of serotonin (5-HT) detection. The BDDME showed a 2-fold increased FSCV response for 5-HT in comparison to dopamine (DA), with a limit of detection of 0.16 µM for 5-HT and 0.26 µM for DA. These results are intended to expand on the development of the next generation BDDME and guide future in vivo experiments, adding to the growing body of literature on implantable devices for neurochemical sensing.

Morphology analysis of PEEK 450G using scanning electron microscopy directly on fast scanning calorimetry chips

To explore the morphology of polyetheretherketone (PEEK), this study employed fast scanning calorimetry (FSC) and scanning electron microscopy (SEM). The objective was to observe the PEEK microstructure under various thermal profiles replicating the additive manufacturing material extrusion process. Samples were observed using SEM directly from the FSC chips, allowing high-accuracy evaluation of the microstructure relative to the thermal profiles. This approach allowed for the evaluation of the microstructure with high accuracy concerning the thermal profiles to which the samples were previously exposed. Each sample was coated with a 10 nm layer of gold–palladium (20–80% ratio), and no etching was necessary to observe the micro features of the microstructure. The approach enabled successful observation and quantification of PEEK microstructure, linking substrate temperature and temperature peaks to microstructural outcomes. Notably, temperature peaks during the process enhanced the formation of well-developed, thick lamellae due to increased chain mobility. Additionally, embryos formed post-remelting of the substrate structure were observed.

Vaporization thermodynamics of normal alkyl azides

Two n-alkyl azides, n-tetradecyl- and n-octadecyl azides, were synthesized and characterized by differential scanning calorimetry and fast scanning calorimetry. Based on the experiments performed, the enthalpies and temperatures of solid-solid transitions and fusion, condensed phase heat capacities, vapor pressures above the liquids, and vaporization enthalpies were obtained, and temperature limits of stability were determined. Combining the newly obtained and existing literature data on the vaporization characteristics of n-alkyl azides, the linear dependences of the vaporization enthalpy and the natural logarithm of vapor pressure on the chain length were derived at 298.15 K and the p-T properties of unstudied members of homologous series were predicted.

Localization and segmentation of atomic columns in supported nanoparticles for fast scanning transmission electron microscopy

To accurately capture the dynamic behavior of small nanoparticles in scanning transmission electron microscopy, high-quality data and advanced data processing is needed. The fast scan rate required to observe structural dynamics inherently leads to very noisy data where machine learning tools are essential for unbiased analysis. In this study, we develop a workflow based on two U-Net architectures to automatically localize and classify atomic columns at particle-support interfaces. The model is trained on non-physical image simulations, achieves sub-pixel localization precision, high classification accuracy, and generalizes well to experimental data. We test our model on both in situ and ex situ experimental time series recorded at 5 frames per second of small Pt nanoparticles supported on CeO2(111). The processed movies show sub-second dynamics of the nanoparticles and reveal site-specific movement patterns of individual atomic columns.

Combining fast scanning chip calorimetry and nanoindentation: Young's modulus and hardness of poly (l-lactic acid) containing α′- and α-crystals

Fast scanning chip calorimetry (FSC) allows subjecting polymer melts to well-defined vitrification, crystal nucleation, and crystal growth pathways and, therefore, precise control of morphologies, from fully amorphous glassy states to semicrystalline structures containing perfect crystals. Due to the required use of nanogram-sized samples, needed to achieve high cooling rates, their mechanical properties, in order to establish structure-property relations, are difficult to assess. In this work, indentation modulus and indentation hardness of FSC samples are successfully determined on example of semicrystalline poly (ʟ-lactic acid) (PLLA) containing spherulitically grown disorder α′- or rather perfect α-crystals, with the correctness of the applied preparation and analyses routes confirmed by nanoindentation measurements on milligram-sized samples prepared through hotstage microscopy, and by applying both static single-step and quasi-continuous stiffness measurements. Modulus and hardness data are consistent with prior analyses of bulk samples, confirming that semicrystalline PLLA containing α-crystals exhibits around 10–20 % higher values of these properties compared to PLLA containing α′-crystals, related to the different molecular-chain packing in the crystal lattice. This work demonstrates that combination of FSC and nanoindentation techniques is an effective tool for determining mechanical properties of samples solidified at specific thermal pathways which otherwise cannot be realized.

Research on the application and prospect of RFID technology

As Radio Frequency Identification (RFID) has the advantages of fast scanning speed, small size, large data storage, high security, and other technologies, it is widely used in various fields to upgrade working efficiency. Meanwhile, as one of the research topics of the Internet of Things (IoT), Radio Frequency Identification also provides the possibility for the development and application scope of IoT. Based on the application principle of Radio Frequency Identification technology, this paper discusses the application of Radio Frequency Identification in the two fields of intelligent libraries and intelligent logistics through literature review and theoretical analysis. Through the analysis of the current situation of RFID application in the library management and logistics industry, this paper discusses the advantages and shortcomings of radio frequency identification technology, and according to the existing problems the future direction of development of the corresponding improvement proposals to promote the further improvement of the application of radio frequency identification technology.

Factors influencing the use of Point Of Care Ultrasound (POCUS) on adult patients by Accident and Emergency Department (A&amp;amp;E) Doctors in Tertiary Care Hospitals in Colombo District, Sri Lanka; a Descriptive Cross-Sectional Study

Introduction:Point of care ultrasound (PoCUS) is an essential component of A&amp;E setting all over the world. It is used for diagnosis and assisting bedside procedures. Usage of PoCUS has been shown to improve quality of patient care. There are no formal studies in Sri Lankan A&amp;E setting to assess level of its usage and the barriers of using it. This study aimed to assess these aspects among ED doctors in three tertiary care hospitals in Colombo district.Methodology:This descriptive study was conducted by self-administered questionnaires distributed among 72 ED doctors working in the above setting. Questionnaire consisted of questions related to sociodemographics, types of PoCUS performed, barriers to PoCUS use etc. Ability to perform PoCUS was assessed by Likert grading from 1 to 5 based on operator’s own opinion. Statistical analysis was done using SPSS.Results: All the tertiary care emergency services had access to an ultrasound machine. PoCUS has been used for a wide variety of bedside scans and therapeutic procedures. Majority has been used to detect free fluid in peritoneal cavity (66.6%) and FAST scans (65.3%). Post graduate doctors (PG) were more confident in configuring PoCUS machine for procedures than non PG doctors (82.8% vs 5.4%). Ability to perform PoCUS was associated with post graduate exposure, &gt;1 year of experience using it and doing &gt;300 procedures in last 3 months (p=0.001). Main barriers identified for PoCUS usage were lack of training and lack of quality ultrasound machine.Discussion: Though PoCUS is mainly performed by PG doctors, important scans such as FAST, intra peritoneal free fluid assessment are done by non-PG doctors too. Compared to similar international studies, less number of latter doctors were capable of doing PoCUS in Sri Lanka. Empowering these doctors with PoCUS skills will improve the sustainably of this service in emergency care setup as they work in units for longer duration. A study where candidates’ skills are assessed by a third party would have provided more accurate reflection of PoCUS usage.Conclusion: Embracing updated technology and further improvement and availability of PoCUS training among ED doctors will enhance sustainable emergency patient care in Sri Lanka.

Coagulation depth estimation using a line scanner for depth-resolved laser speckle contrast imaging.

Partial-thickness burn wounds extend partially through the dermis, leaving many pain receptors intact and making the injuries very painful. Due to the painfulness, quick assessment of the burn depth is important to not delay surgery of the wound if needed. Laser speckle imaging (LSI) of skin blood flow can be helpful in finding severe coagulation zones with impaired blood flow. However, LSI measurements are typically too superficial to properly reach the full depth of the adult dermis and cannot resolve the flow in depth. Diffuse correlation spectroscopy (DCS) uses varying source-detector separations to allow differentiation of flow depths but requires time-consuming 2D scanning to form an image of the burn area. We here present a prototype for a hybrid DCS and LSI technique called speckle contrast diffuse correlation spectroscopy (scDCS) with the novel approach of using a laser line as a source and using the speckle contrast of averaged images to obtain an estimate of static scattering in the tissue. This will allow for fast non-contact 1D scanning to perform 3D tomographic imaging, making quantitative estimates of the depth and area of the coagulation zone from burn wounds. Simulations and experimental results from a volumetric flow phantom and a gelatin wedge phantom show promise to determine coagulation depth. The aim is to develop a method that, in the future, could provide more quantitative estimates of coagulation depth in partial thickness burn wounds to better estimate when surgery is needed.

Focal plane imaging system based on CMOS terahertz detector

Abstract Terahertz technology has shown remarkable potential for application in the field of imaging since it offers several particular advantages such as great penetration capabilities, non-ionization and high instantaneous bandwidth. This paper presents a focal plane imging system based on CMOS terathertz detector for forward-looking detection. The focal plane imaging system has several advantages, including fast scanning, simple composition, low cost, and easy integration of a CMOS detector. It is composed of a terahertz radiation source, a Polytetrafluoroethylene (PTFE) lens and a broadband CMOS detector. The detector was fabricated in a 65 nm CMOS process. The operating frequency range of the detector covers 75 GHz to 1000 GHz. Measurement results have shown that the focal plane imaging system is capable of stably imaging at frequencies of 100 GHz and 220 GHz. To address the issue of missing information in measurement images, the morphological closing algorithm is employed to process the original image, successfully filling in the missing information and improving image quality.

The glass transition temperature of anhydrous amorphous calcium carbonate

Abstract Amorphous calcium carbonate (ACC) is the least stable polymorph of calcium carbonates. It has been identified to play an important role in nature (e.g., biomineralization and speleothem formation), where it acts as a precursor for the transformation to more stable polymorphs such as calcite. Furthermore, the use of ACC in technical applications requires a robust understanding of the material’s properties. We present the first study that reveals the existence of a glass transition for synthetic and anhydrous ACC. The glass transition occurs at 339 °C. Such measurements are impossible with conventional differential scanning calorimetry (DSC) due to the high tendency of ACC to crystallize. Fast scanning DSC with heating rates of 500 °C/s and higher, however, can be used to separate the endothermic glass transition signature from the exothermic crystallization event since crystallization is shifted to higher temperatures. This allows the detection and quantification of the glass transition for ACC. These observations indicate that ACC is a structural glass and are especially significant because the synthesis of ACC, precipitation from a solution followed by lyophilization, contrasts with the more conventional and well-known route of glass formation–the rapid cooling of a melt. Moreover, we prove that a structural glass can be produced from a simple single-component carbonate system.

Laser Machining at High ∼PW/cm2 Intensity and High Throughput

Laser machining by ultra-short (sub-ps) pulses at high intensity offers high precision, high throughput in terms of area or volume per unit time, and flexibility to adapt processing protocols to different materials on the same workpiece. Here, we consider the challenge of optimization for high throughput: how to use the maximum available laser power and larger focal spots for larger ablation volumes by implementing a fast scan. This implies the use of high-intensity pulses approaching ∼PW/cm2 at the threshold where tunneling ionization starts to contribute to overall ionization. A custom laser micromachining setup was developed and built to enable high speed, large-area processing, and easy system reconfiguration for different tasks. The main components include the laser, stages, scanners, control system, and software. Machining of metals such as Cu, Al, or stainless steel and fused silica surfaces at high fluence and high exposure doses at high scan speeds up to 3 m/s were tested for the fluence scaling of ablation volume, which was found to be linear. The largest material removal rate was 10 mm3/min for Cu and 20 mm3/min for Al at the maximum power 80 W (25 J/cm2 per pulse). Modified surfaces are color-classified for their appearance, which is dependent on surface roughness and chemical modification. Such color-coding can be used as a feedback parameter for industrial process control.