Enhancing sensitivity of pH-weighted MRI with combination of amide and guanidyl CEST

Jin, Tao,Wang, Ping,Hitchens, T. Kevin,Kim, Seong-Gi Elsevier 2017 NeuroImage Vol.157 No.-

<P><B>Abstract</B></P> <P>Amide-proton-transfer weighted (APTw) MRI has emerged as a non-invasive pH-weighted imaging technique for studies of several diseases such as ischemic stroke. However, its pH-sensitivity is relatively low, limiting its capability to detect small pH changes. In this work, computer simulations, protamine phantom experiments, and in vivo gas challenge and experimental stroke in rats showed that, with judicious selection of the saturation pulse power, the amide-CEST at 3.6ppm and guanidyl-CEST signals at 2.0ppm changed in opposite directions with decreased pH. Thus, the difference between amide-CEST and guanidyl-CEST can enhance the pH measurement sensitivity, and is dubbed as pH<SUB>enh</SUB>. Acidification induced a negative contrast in APTw, but a positive contrast in pH<SUB>enh</SUB>. In vivo experiments showed that pH<SUB>enh</SUB> can detect hypercapnia-induced acidosis with about 3-times higher sensitivity than APTw. Also, pH<SUB>enh</SUB> slightly reduced gray and white matter contrast compared to APTw. In stroke animals, the CEST contrast between the ipsilateral ischemic core and contralateral normal tissue was −1.85 ± 0.42% for APTw and 3.04 ± 0.61% (n = 5) for pH<SUB>enh</SUB>, and the contrast to noise was 2.9 times higher for pH<SUB>enh</SUB> than APTw. Our results suggest that pH<SUB>enh</SUB> can be a useful tool for non-invasive pH-weighted imaging.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The pH<SUB>enh</SUB> MRI combines the amide- and guanidyl-CEST effects to enhance the pH-sensitivity. </LI> <LI> With B<SUB>1</SUB>-tuning, acidosis induce a negative and a positive contrast for the amide- and guanidyl-CEST signal, respectively. </LI> <LI> In pH<SUB>enh</SUB>, the RF powers are also adjusted to match the direct water saturation at amide and guanidyl frequencies. </LI> <LI> Phantom and in vivo studies confirm a higher pH-sensitivity for pH<SUB>enh</SUB> over APT-weighted MRI. </LI> </UL> </P>

Chemical exchange-sensitive spin-lock MRI of glucose analog 3-O-methyl-d-glucose in normal and ischemic brain

Jin, Tao,Mehrens, Hunter,Wang, Ping,Kim, Seong-Gi SAGE Publications 2018 Journal of cerebral blood flow and metabolism Vol.38 No.5

<P> Glucose transport is important for understanding brain glucose metabolism. We studied glucose transport with a presumably non-toxic and non-metabolizable glucose analog, 3-O-methyl-d-glucose, using a chemical exchange-sensitive spin-lock MRI technique at 9.4 Tesla. 3-O-methyl-d-glucose showed comparable chemical exchange properties with d-glucose and 2-deoxy-d-glucose in phantoms, and higher and lower chemical exchange-sensitive spin-lock sensitivity than Glc and 2-deoxy-d-glucose in in vivo experiments, respectively. The changes of the spin-lattice relaxation rate in the rotating frame (Δ R1ρ) in normal rat brain peaked at ∼15 min after the intravenous injection of 1 g/kg 3-O-methyl-d-glucose and almost maintained a plateau for >1 h. Doses up to 4 g/kg 3-O-methyl-d-glucose were linearly correlated with Δ R1ρ. In rats with focal ischemic stroke, chemical exchange-sensitive spin-lock with 3-O-methyl-d-glucose injection at 1 h after stroke onset showed reduced Δ R1ρ in the ischemic core but higher Δ R1ρ in the peri-core region compared to normal tissue, which progressed into the ischemic core at 3 h after stroke onset. This suggests that the hyper-chemical exchange-sensitive spin-lock region observed at 1 h is the ischemic penumbra at-risk of infarct. In summary, 3-O-methyl-d-glucose-chemical exchange-sensitive spin-lock can be a sensitive MRI technique to probe the glucose transport in normal and ischemic brains. </P>

Synthesis of g-C3N4/CQDs composite and its photocatalytic degradation property for Rhodamine B

Jin Tao,Liu Chengbao,Chen Feng,Qian Junchao,Qiu Yongbin,Meng Xianrong,Chen Zhigang 한국탄소학회 2022 Carbon Letters Vol.32 No.6

To solve the problem of water pollution, researchers have proposed a photocatalytic degradation technology, in which the key factor is the development of efficient photocatalytic materials. Graphitic carbon nitride (g-C3N4), an n-type semiconductor, has been widely studied due to its suitable band gap (2.7 eV), low cost, easy preparation, non-toxicity, and high photostability. However, the pure-phase g-C3N4 still has defects such as low specific surface area, insufficient visible light absorption, low charge mobility, few active sites for interfacial reaction, and easy recombination of photogenerated electron–hole pairs, which leads to the lower photocatalytic activity of g-C3N4. Aiming at the problems mentioned above, this paper focus on the synthesis of g-C3N4-based composites with high photocatalytic activity via lemon juice induction method. Thiourea and lemon juice were selected as precursors, and carbon quantum dots (CQDs) as electron mediators were introduced anchoring on the surface of g-C3N4 to build g-C3N4/CQDs with compact interface. The results showed that small-sized CQDs are uniformly distributed on the surface of g-C3N4, and the g-C3N4/CQDs composite has a 2D0D structure, which reduces the recombination of photogenerated electron–hole pairs. The photocatalytic degradation efficiency of 4% g-C3N4/CQDs for RhB reaches the highest data of 90.9%, and the photocatalytic degradation rate is 0.016 min−1, which is about 2.3 times that of g-C3N4. After four cycles of photocatalytic reaction, the photocatalytic degradation efficiency of the material remained at 81.7%. Therefore, the g-C3N4/CQDs synthesized via lemon juice induction has a more stable microstructure, and the charge separation efficiency is greatly improved, which is suitable for practical photocatalytic environmental protection.

Mapping brain glucose uptake with chemical exchange-sensitive spin-lock magnetic resonance imaging

Jin, Tao,Mehrens, Hunter,Hendrich, Kristy S,Kim, Seong-Gi Nature Publishing Group 2014 Journal of cerebral blood flow and metabolism Vol.34 No.8

<P>Uptake of administered D-glucose (Glc) or 2-deoxy-D-glucose (2DG) has been indirectly mapped through the chemical exchange (CE) between glucose hydroxyl and water protons using CE-dependent saturation transfer (glucoCEST) magnetic resonance imaging (MRI). We propose an alternative technique—on-resonance CE-sensitive <I>spin-lock</I> (CESL) MRI—to enhance responses to glucose changes. Phantom data and simulations suggest higher sensitivity for this ‘glucoCESL' technique (versus glucoCEST) in the intermediate CE regime relevant to glucose. Simulations of CESL signals also show insensitivity to <I>B</I><SUB>0</SUB>-fluctuations. Several findings are apparent from <I>in vivo</I> glucoCESL studies of rat brain at 9.4 Tesla with intravenous injections. First, dose-dependent responses are nearly linearly for 0.25-, 0.5-, and 1-g/kg Glc administration (obtained with 12-second temporal resolution), with changes robustly detected for all doses. Second, responses at a matched dose of 1 g/kg are much larger and persist for a longer duration for 2DG versus Glc administration, and are minimal for mannitol as an osmolality control. And third, with similar increases in steady-state blood glucose levels, glucoCESL responses are ∼2.2 times higher for 2DG versus Glc, consistent with their different metabolic properties. Overall, we show that glucoCESL MRI could be a highly sensitive and quantifiable tool for glucose transport and metabolism studies.</P>

Hydrothermal fabrication of robustly superhydrophobic cotton fibers for efficient separation of oil/water mixtures and oil-in-water emulsions

Jintao Wang,Fenlan Han,Bo Liang,Guihong Geng 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.54 No.-

In this study, superhydrophobic and superoleophilic cotton fibers are fabricated by simple one-step hydrothermal route followed by modification with silane. The obtained fibers show selective sorption ability to the oils from water, high sorption capacities, excellent recyclability, and quick sorption rate. The fibers also exhibit outstanding superhydrophobic stability under a variety of corrosive solutions and hot water, which enables it application for the separation of the oils from harsh water environments. Moreover, the superhydrophobic fibers in conjunction with a tube (valid tube area: 0.5 cm2) that connected to a vacuum system (vacuum pressure: 0.03 MPa) is capable of collecting up to 200 times its self-weight in gasoline within 20 s. The coated fibers can also selectively harvest oils from oil/water mixtures under extreme turbulent condition. More importantly, the coated fibers can separate micronsized oil droplets from oil-in-water emulsions with a high separation efficiency (transparency for solvent oils: >91%) that is beyond what can be obtained by most traditional separation methods. All these performances make the as-prepared cotton fibers ideally suited for the oil-spill cleanups and water purification.

Three-dimensional flow simulation of transient power interruption process of a prototype pump-turbine at pump mode

Jintao Liu,Shuhong Liu,Yuekun Sun,Lei Jiao,Yulin Wu,Leqin Wang 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

The transient power failure process of a prototype pump-turbine was studied numerically by three-dimensional (3-D) simulations. Fluid coupling and dynamic mesh (DM) method were used to calculate the rotational speed of the runner. Simulations were performed based on turbulence model. Specific transient characteristics, such as the flow rate, head, rotational speed, were analyzed. The pumpturbine had a minimum head and a maximum axial force when the flow rate was 0 during the transient process. Pressure fluctuations increased when the pump-turbine ran at pump braking mode. Reverse flow in the casing as well as stall phenomenon in the runner had a great effect on the change of head. Pressure in the runner was greatly reduced when the pump-turbine ran at pump braking mode. The computational method could be used to interpret the abnormal phenomenon by the analysis of flow mechanism during a transient process.

Analysis of Ocular Blood Flow Autoregulation in Human by Using an ARX Model

Jintao Yu,Zhiping Yang,Lin Wang,Fang Feng 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.9

Phase Switching Mechanism for WiFi-based Long Distance Networks in Industrial Real-Time Applications

( Jintao Wang ),( Xi Jin ),( Peng Zeng ),( Zhaowei Wang ),( Ming Wan ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.1

High-quality industrial control is critical to ensuring production quality, reducing production costs, improving management levels and stabilizing equipment and long-term operations. WiFi-based Long Distance (WiLD) networks have been used as remote industrial control networks. Real-time performance is essential to industrial control. However, the original mechanism of WiLD networks does not minimize end-to-end delay and restricts improvement of real-time performance. In this paper, we propose two algorithms to obtain the transmitting/receiving phase cycle length for each node such that real time constraints can be satisfied and phase switching overhead can be minimized. The first algorithm is based on the branch and bound method, which identifies an optimal solution. The second is a fast heuristic algorithm. The experimental results show that the execution time of the algorithm based on branch and bound is less than that of the heuristic algorithm when the network is complex and that the performance of the heuristic algorithm is close to the optimal solution.

Weld Seam Recognition Based On CCD Image Processing

Jintao Yu,Xian Li,Mingli Ding,Shicheng Dong,Junling Li 보안공학연구지원센터 2015 International Journal of Signal Processing, Image Vol.8 No.6

Weld seam recognition is the key technique in visual tracking research. Based on the weld image features, the image preprocessing and the linear feature extraction method of the weld seam recognition are designed. The extended adaptive median filtering method and modified Otsu adaptive threshold selection method for image segmentation are used in the image pre-processing process, to remove the noise and compress the image data. Through comparing with several other edge operators, the Roberts operator is chosen to achieve the goal of detecting the welding edge. Finally, the weld seam information is extracted through Hough transform and a satisfied result can be acquired. The study provides a theoretical support for the following designing of the weld tracking system.

Experimental Study of Seismic Evaluation for Cabinets in Nuclear Power Plants based on Vibration Tests

Jintao Cui,Ki Young Koo,Sung Gook Cho,Dookie Kim 대한토목학회 2009 대한토목학회 학술대회 Vol.2009 No.10