371 research outputs found
Immobilized biocatalytic process to prepare enantiopure pregabalin intermediate using engineered hydantoinase
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The Advantage of PET and CT Integration in Examination of Lung Tumors
Purpose. To evaluate the diagnosis value of integrated positron emission tomography and computed tomography (PET/CT) with lung masses, this study emphasized the correlation between tumor size and maximum standardized uptake value (SUVmax) in selected regions of interest (ROI) of lung masses.
Material and Methods. A retrospective analysis was performed on 85 patients with solid pulmonary lesions, all verified by pathology. The morphology, edge (speculated margins and lobule), size, density of pulmonary masses, and on-chest CT images were reviewed. The SUVmax in ROI of pulmonary masses was calculated. Results. Among the 85 patients with lung masses, 59 patients presented with pulmonary malignant neoplasm and 26 patients with benign lesions. The sensitivity, specificity, and accuracy were 89.8%, 61.5%, 81.2%, respectively, for PET measurement only, 88.1%, 65.4%, 81.2% for CT only, and 96.6%, 80.8%, 91.8% for PET/CT. The size of pulmonary malignant neoplasm in the 59 patients was apparently correlated with the ROI's SUVmax (r=0.617, P<.001). However, the size of pulmonary benign mass in the 26 patients was not correlated with the SUVmax. Conclusion. PET/CT is of greater value in characterization of lung masses than PET and CT performed separately. The examination of lung tumor can be further specified by the correlation between the size of pulmonary malignant neoplasm and the ROI's SUVmax
Targeting immune co-stimulatory effects of PD-L1 and PD-L2 might represent an effective therapeutic strategy in stroke
Stroke outcome is worsened by the infiltration of inflammatory immune cells into ischemic brains. Our recent study demonstrated that PD-L1- and to a lesser extent PD-L2-deficient mice had smaller brain infarcts and fewer brain-infiltrating cells vs. wild-type (WT) mice, suggesting a pathogenic role for PD-ligands in experimental stroke. We sought to ascertain PD-L1 and PD-L2-expressing cell types that affect T-cell activation, post-stroke in the context of other known co-stimulatory molecules. Thus, cells from male WT and PD-L-deficient mice undergoing 60 min of middle cerebral artery occlusion (MCAO) followed by 96 h of reperfusion were treated with neutralizing antibodies to study co-stimulatory and co-inhibitory interactions between CD80, cytotoxic T-lymphocyte antigen-4 (CTLA-4), PD-1, and PD-Ls that regulate CD8(+) and CD4(+) T-cell activation. We found that antibody neutralization of PD-1 and CTLA-4 signaling post-MCAO resulted in higher proliferation in WT CD8(+) and CD4(+) T-cells, confirming an inhibitory role of PD-1 and CTLA-4 on T-cell activation. Also, CD80/CD28 interactions played a prominent regulatory role for the CD8(+) T-cells and the PD-1/PD-L2 interactions were dominant in controlling the CD4(+) T-cell responses in WT mice after stroke. A suppressive phenotype in PD-L1-deficient mice was attributed to CD80/CTLA-4 and PD-1/PD-L2 interactions. PD-L2 was crucial in modulating CD4(+) T-cell responses, whereas PD-L1 regulated both CD8(+) and CD4(+) T-cells. To establish the contribution of PD-L1 and PD-L2 on regulatory B-cells (Bregs), infarct volumes were evaluated in male PD-L1- and PD-L2-deficient mice receiving IL-10(+) B-cells 4h post-MCAO. PD-L2- but not PD-L1-deficient recipients of IL-10(+) B-cells had markedly reduced infarct volumes, indicating a regulatory role of PD-L2 on Bregs. These results imply that PD-L1 and PD-L2 differentially control induction of T- and Breg-cell responses after MCAO, thus suggesting that selective targeting of PD-L1 and PD-L2 might represent a valuable therapeutic strategy in stroke
Ultra-low threshold continuous-wave quantum dot mini-BIC lasers
Highly compact lasers with ultra-low threshold and single-mode continuous
wave (CW) operation have been a long sought-after component for photonic
integrated circuits (PICs). Photonic bound states in the continuum (BICs), due
to their excellent ability of trapping light and enhancing light-matter
interaction, have been investigated in lasing configurations combining various
BIC cavities and optical gain materials. However, the realization of BIC laser
with a highly compact size and an ultra-low CW threshold has remained elusive.
We demonstrate room temperature CW BIC lasers in the 1310 nm O-band wavelength
range, by fabricating a miniaturized BIC cavity in an InAs/GaAs epitaxial
quantum dot (QD) gain membrane. By enabling effective trapping of both light
and carriers in all three dimensions, ultra-low threshold of 12 {\mu}W (0.052
kW/cm^2) is achieved. Single-mode lasing is also realized in cavities as small
as only 5*5 unit-cells (~2.5*2.5 {\mu}m^2 cavity size) with a mode volume of
1.16({\lambda}/n)^3. With its advantages in terms of a small footprint,
ultralow power consumption, robustness of fabrication and adaptability for
integration, the mini-BIC lasers offer a perspective light source for future
PICs aimed at high-capacity optical communications, sensing and quantum
information
Single-Mode, High Repetition Rate, Compact Ho:YLF Laser for Space-Borne Lidar Applications
A single transverse/longitudinal mode, compact Q-switched Ho:YLF laser has been designed and demonstrated for space-borne lidar applications. The pulse energy is between 34-40 mJ for 100-200 Hz operation. The corresponding peak power is >1 MW
Sensitive Infrared Signal Detection by Upconversion Technique
We demonstrated upconversion assisted detection of a 2.05-micron signal by sum frequency generation to generate a 700-nm light using a bulk periodically poled lithium niobate crystal. The achieved 94% intrinsic upconversion efficiency and 22.58% overall detection efficiency at a pW level of 2.05 micron pave the path to detect extremely weak infrared (IR) signals for remote sensing applications
Ubiquitous short-range order in multi-principal element alloys
Recent research in multi-principal element alloys (MPEAs) has increasingly
focused on the exploration and exploitation of short-range order (SRO) to
enhance material performance. However, the understanding of SRO formation and
the precise tuning of it within MPEAs remains poorly understood, limiting the
comprehension of its impact on material properties and impeding the advancement
of SRO engineering. Here, leveraging advanced additive manufacturing techniques
that produce samples with a wide range of cooling rates (up to 10^7 K/s) and an
improved quantitative electron microscopy method, we characterize SRO in three
CoCrNi-based MPEAs to unravel the role of processing route and thermal history
on SRO. Surprisingly, irrespective of the processing and thermal treatment
applied, all samples exhibit similar levels of SRO, suggesting that prevalent
SRO may form during the solidification process. Atomistic simulations of
solidification verify that local chemical ordering arises in the liquid-solid
interface (solidification front) even under the extreme cooling rate of 10^11
K/s. This phenomenon stems from the swift atomic diffusion in the supercooled
liquid, which matches or even surpasses the rate of solidification. Therefore,
SRO is an inherent characteristic of most MPEAs, insensitive to variations in
cooling rates and annealing treatments typically available in experiments.
Integrating thermal treatment with other strategies, such as mechanical
deformation and irradiation, might be more effective approaches for harnessing
SRO to achieve controlled material properties.Comment: 27 pages, 5 figure
SHIELD : An Evaluation Benchmark for Face Spoofing and Forgery Detection with Multimodal Large Language Models
Multimodal large language models (MLLMs) have demonstrated remarkable
problem-solving capabilities in various vision fields (e.g., generic object
recognition and grounding) based on strong visual semantic representation and
language reasoning ability. However, whether MLLMs are sensitive to subtle
visual spoof/forged clues and how they perform in the domain of face attack
detection (e.g., face spoofing and forgery detection) is still unexplored. In
this paper, we introduce a new benchmark, namely SHIELD, to evaluate the
ability of MLLMs on face spoofing and forgery detection. Specifically, we
design true/false and multiple-choice questions to evaluate multimodal face
data in these two face security tasks. For the face anti-spoofing task, we
evaluate three different modalities (i.e., RGB, infrared, depth) under four
types of presentation attacks (i.e., print attack, replay attack, rigid mask,
paper mask). For the face forgery detection task, we evaluate GAN-based and
diffusion-based data with both visual and acoustic modalities. Each question is
subjected to both zero-shot and few-shot tests under standard and chain of
thought (COT) settings. The results indicate that MLLMs hold substantial
potential in the face security domain, offering advantages over traditional
specific models in terms of interpretability, multimodal flexible reasoning,
and joint face spoof and forgery detection. Additionally, we develop a novel
Multi-Attribute Chain of Thought (MA-COT) paradigm for describing and judging
various task-specific and task-irrelevant attributes of face images, which
provides rich task-related knowledge for subtle spoof/forged clue mining.
Extensive experiments in separate face anti-spoofing, separate face forgery
detection, and joint detection tasks demonstrate the effectiveness of the
proposed MA-COT. The project is available at
https//github.com/laiyingxin2/SHIEL
Advances in High Energy Solid-State 2-micron Laser Transmitter Development for Ground and Airborne Wind and CO2 Measurements
Sustained research efforts at NASA Langley Research Center (LaRC) during last fifteen years have resulted in a significant advancement in 2-micron diode-pumped, solid-state laser transmitter for wind and carbon dioxide measurement from ground, air and space-borne platform. Solid-state 2-micron laser is a key subsystem for a coherent Doppler lidar that measures the horizontal and vertical wind velocities with high precision and resolution. The same laser, after a few modifications, can also be used in a Differential Absorption Lidar (DIAL) system for measuring atmospheric CO2 concentration profiles. Researchers at NASA Langley Research Center have developed a compact, flight capable, high energy, injection seeded, 2-micron laser transmitter for ground and airborne wind and carbon dioxide measurements. It is capable of producing 250 mJ at 10 Hz by an oscillator and one amplifier. This compact laser transmitter was integrated into a mobile trailer based coherent Doppler wind and CO2 DIAL system and was deployed during field measurement campaigns. This paper will give an overview of 2-micron solid-state laser technology development and discuss results from recent ground-based field measurements
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