A Localized High-Concentration Water/Organic Hybrid Electrolyte for 2.5 V Li4Ti5O12/LiMn2O4 Batteries

The "solvent-in-salt" electrolytes for an aqueous system, including "water-in-salt" electrolytes and "bisolvent-in-salt" electrolytes, have shown significantly improved electrochemical stability toward low-voltage anodes and high-voltage cathodes. However, the heavy use of salt raises concerns of high cost, high viscosity, inferior wettability, and poor low-temperature performance. Herein, a "localized bisolvent-in-salt electrolyte" is proposed by introducing 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) as the diluent to the high-concentration water/sulfolane hybrid (BSiS-SL) electrolytes, forming a ternary solvent-based electrolyte, Li(H₂O)_0.9SL_1.3·TTE_1.3 (HS-TTE). The introduction of TTE dilutes the compact ionic clusters, while the original primary Li⁺ solvation structure remains, and in the meantime, boosts the formation of a robust solid electrolyte interphase. As a result, a wide electrochemically stable window of 4.4 V is achieved. In comparison with the bisolvent BSiS-SL system, the trisolvent HS-TTE electrolyte exhibits a low salt concentration of 2.1 mol kg^-1, resulting in drastically reduced viscosity, superb separator wettability, and largely improved low-temperature performance. The constructed 2.5 V Li₄Ti₅O₁₂/LiMn₂O₄ cell shows an excellent capacity retention of 80.7% after 800 cycles, and the cell can even work at -30 °C. With these extraordinary advantages, the fundamental designing strategy of the HS-TTE electrolyte developed in this work can promote the practical applications of solvent-in-salt electrolytes.

A High-Performance Lithium Metal Battery with Ion-Selective Nanofluidic Transport in a Conjugated Microporous Polymer Protective Layer

Lithium metal is the "holy grail" of anodes, capable of unlocking the full potential of cathodes in next-generation batteries. However, the use of pure lithium anodes faces several challenges in terms of safety, cycle life, and rate capability. Herein, a solution-processable conjugated microporous thermosetting polymer (CMP) is developed. The CMP can be further converted into a large-scale membrane with nanofluidic channels (5-6 Å). These channels can serve as facile and selective Li-ion diffusion pathways on the surfaces of lithium anodes, thereby ensuring stable lithium stripping/plating even at high areal current densities. CMP-modified lithium anodes (CMP-Li) exhibit cycle stability of 2550 h at an areal current density of 20 mA cm^-2 . Furthermore, CMP is readily amenable to solution-processing and spray coating, rendering it highly applicable to continuous roll-to-roll lithium metal treatment processes. Pouch cells with CMP-Li as the anode and LiNi_0.8 Co_0.1 Mn_0.1 O₂ (NCM811) as the cathode exhibits a stable energy density of 400 Wh kg^-1 .

Inducing rapid polysulfide transformation through enhanced interfacial electronic interaction for lithium-sulfur batteries

Sluggish dynamics of polysulfide (LiPS) conversion leads to reduced utilization of active sulfur and rapid capacity decay. Introducing catalysts into lithium-sulfur battery systems is a feasible and imperative strategy to tackle this problem. Previous research studies have mainly been focused on selecting new catalysts and design functional structures to improve performance, and ignoring the interaction between catalysts and their carriers. Herein, by simply fabricating a high-efficiency ZnS quantum dot@graphene nanosheet catalyst (ZnS QD@rGO), we utilized enhanced interfacial electronic interaction to accelerate polysulfide conversion for high energy density Li-S batteries. With the smaller size of ZnS, the interfacial electronic interaction becomes more enhanced, which was evidenced by DFT calculations and XPS experiments. After mixing with sulfur, the electrodes achieved a high capacity of 857.8 mA h g^-1 at 1 C and a retention of 91.2% after 300 cycles. Also, a sulfur cathode with a high actual capacity of ∼4.0 mA h cm^-2 could be obtained, with no obvious capacity decay within 100 cycles. We believe that this strategy represents a new perspective on designing efficient high-load electrodes for Li-S batteries.

Single-Atom Coated Separator for Robust Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are strong contenders among lithium batteries due to superior capacity and energy density, but the polysulfide shuttling effect limits the cycle life and reduces energy efficiency due to a voltage gap between charge and discharge. Here, we demonstrate that graphene foam impregnated with single-atom catalysts (SACs) can be coated on a commercial polypropylene separator to catalyze polysulfide conversion, leading to a reduced voltage gap and a much improved cycle life. Also, among Fe/Co/Ni SACs, Fe SACs may be a better option to be used in Li-S systems. By deploying SACs in the battery separator, cycling stability improves hugely, especially considering relatively high sulfur loading and ultralow SAC contents. Even at a metal loading of ∼2 μg in the whole cell, an Fe SAC-modified separator delivers superior Li-S battery performance even at high sulfur loading (891.6 mAh g^-1, 83.7% retention after 750 cycles at 0.5C). Our work further enriches and expands the application of SACs catalyzing polysulfide blocking and conversion and improving round trip efficiencies in batteries, without side effects such as electrolyte and electrode decomposition.

Neamine induces neuroprotection after acute ischemic stroke in type one diabetic rats

INTRODUCTION

Angiogenin is a member of the ribonuclease superfamily and promotes degradation of the basement membrane and the extracellular matrix. After stroke in type one diabetes (T1DM) rats, Angiogenin is significantly increased and the Angiogenin is inversely correlated with functional outcome. Neamine, an aminoglycoside antibiotic, blocks nuclear translocation of Angiogenin, thereby abolishing the biological activity of Angiogenin. In this study, we therefore investigated the effect and underlying protective mechanisms of Neamine treatment of stroke in T1DM.

METHODS

T1DM was induced in male Wistar rats by streptozotocin (60mg/kg, ip), and T1DM rats were subjected to embolic middle cerebral artery occlusion (MCAo). Neamine (10mg/kg ip) was administered at 2, 24 and 48h after the induction of embolic MCAo. A battery of functional outcome tests was performed. Blood-brain barrier (BBB) leakage, and lesion volume were evaluated and immunostaining, and Western blot were performed.

RESULTS

Neamine treatment of stroke in T1DM rats significantly decreased BBB leakage and lesion volume as well as improved functional outcome compared to T1DM-control. Neamine also significantly decreased apoptosis and cleaved caspase-3 in the ischemic brain. Using immunostaining, we found that Neamine treatment significantly decreased nuclear Angiogenin, nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) activity, advanced glycation endproducts receptor (RAGE) number, the positive area of toll-like receptor 4 (TLR4) and increased Angeopoietin-1 expression compared to T1DM-MCAo control rats. Western blot results are consistent with the immunostaining.

CONCLUSION

Neamine treatment of stroke is neuroprotective in T1DM rats. Inhibition of neuroinflammatory factor expression and decrease of BBB leakage may contribute to Neamine-induced neuroprotective effects after stroke in T1DM rats.

Combination treatment of stroke with sub-therapeutic doses of Simvastatin and human umbilical cord blood cells enhances vascular remodeling and improves functional outcome

Human umbilical cord blood cells (HUCBCs) have been employed as a restorative treatment for experimental stroke. In this study, we investigated whether transplantation of sub-therapeutic doses of HUCBCs and Simvastatin enhances cerebral vascular remodeling after stroke. Adult male Wistar rats (n=34) were subjected to transient middle cerebral artery occlusion (MCAo) and treated with: phosphate-buffered solution (PBS, gavaged daily for 7 days); Simvastatin (0.5mg/kg, gavaged daily for 7 days); HUCBCs (1×10(6), injected once via tail vein); and combination Simvasatin with HUCBCs, starting at 24h after MCAo. There was no significant difference between Simvastatin- or HUCBC-monotherapy and MCAo-alone group. Combination treatment 24h post-stroke significantly increased the perimeter of von Willebrand factor (vWF)-positive vessels, the diameter and density of alpha smooth muscle actin (αSMA)-positive arteries, and the percentage of 5-bromodeoxyuridine (BrdU)-positive endothelial cells (ECs) in the ischemic boundary zone (IBZ) compared with MCAo-alone or HUCBC-monotherapy 14 days after MCAo (p<0.05, n=8/group); Combination treatment significantly increased the densities of vWF-vessels and αSMA-arteries as well as the densities of BrdU-ECs and BrdU-positive smooth muscle cells (SMCs) in vascular walls in the IBZ compared with Simvastatin-monotherapy. Moreover, the increased BrdU-ECs and BrdU-SMCs were significantly correlated with neurological functional outcome 14 days after MCAo. Combination treatment also significantly increased the expression of Angiopoietin-1 (Ang1), Tie2 and Occludin in the IBZ (p<0.05, n=8/group). The in vitro experiments showed that combination treatment and Ang1 significantly increased capillary-like tube formation and arterial cell migration; anti-Ang1 significantly reduced combination treatment-induced tube-formation and artery cell migration (p<0.05, n=6/group). These findings indicated that a combination of sub-therapeutic doses of Simvastatin and HUCBCs treatment of stroke increases Ang1/Tie2 and Occludin expression in the ischemic brain, amplifies endogenous angiogenesis and arteriogenesis, and enhances vascular remodeling which in concert may contribute to functional outcome after stroke.

A cone beam filtered backprojection (CB-FBP) reconstruction algorithm for a circle-plus-two-arc orbit

The circle-plus-arc orbit possesses advantages over other "circle-plus" orbits for the application of x-ray cone beam (CB) volume CT in image-guided interventional procedures requiring intraoperative imaging, in which movement of the patient table is to be avoided. A CB circle-plus-two-arc orbit satisfying the data sufficiency condition and a filtered backprojection (FBP) algorithm to reconstruct longitudinally unbounded objects is presented here. In the circle suborbit, the algorithm employs Feldkamp's formula and another FBP implementation. In the arc suborbits, an FBP solution is obtained originating from Grangeat's formula, and the reconstruction computation is significantly reduced using a window function to exclude redundancy in Radon domain. The performance of the algorithm has been thoroughly evaluated through computer-simulated phantoms and preliminarily evaluated through experimental data, revealing that the algorithm can regionally reconstruct longitudinally unbounded objects exactly and efficiently, is insensitive to the variation of the angle sampling interval along the arc suborbits, and is robust over practical x-ray quantum noise. The algorithm's merits include: only 1D filtering is implemented even in a 3D reconstruction, only separable 2D interpolation is required to accomplish the CB backprojection, and the algorithm structure is appropriate for parallel computation.

Cone beam volume CT image artifacts caused by defective cells in x-ray flat panel imagers and the artifact removal using a wavelet-analysis-based algorithm

The application of x-ray flat panel imagers (FPIs) in cone beam volume CT (CBVCT) has attracted increasing attention. However, due to a deficient semiconductor array manufacturing process, defective cells unavoidably exist in x-ray FPIs. These defective cells cause their corresponding image pixels in a projection image to behave abnormally in signal gray level, and result in severe streak and ring artifacts in a CBVCT image reconstructed from the projection images. Since a three-dimensional (3-D) back-projection is involved in CBVCT, the formation of the streak and ring artifacts is different from that in the two-dimensional (2-D) fan beam CT. In this paper, a geometric analysis of the abnormality propagation in the 3D back-projection is presented, and the morphology of the streak and ring artifacts caused by the abnormality propagation is investigated through both computer simulation and phantom studies. In order to calibrate those artifacts, a 2D wavelet-analysis-based statistical approach to correct the abnormal pixels is proposed. The approach consists of three steps: (1) the location-invariant defective cells in an x-ray FPI are recognized by applying 2-D wavelet analysis on flat-field images, and a comprehensive defective cell template is acquired; (2) based upon the template, the abnormal signal gray level of the projection image pixels corresponding to the location-invariant defective cells is replaced with the interpolation of that of their normal neighbor pixels; (3) that corresponding to the isolated location-variant defective cells are corrected using a narrow-windowed median filter. The CBVCT images of a CT low-contrast phantom are employed to evaluate this proposed approach, showing that the streak and ring artifacts can be reliably eliminated. The novelty and merit of the approach are the incorporation of the wavelet analysis whose intrinsic multi-resolution analysis and localizability make the recognition algorithm robust under variable x-ray exposure levels between 30% and 70% of the dynamic range of an x-ray FPI.

Flat panel detector-based cone-beam volume CT angiography imaging: system evaluation

Preliminary evaluation of recently developed large-area flat panel detectors (FPDs) indicates that FPDs have some potential advantages: compactness, absence of geometric distortion and veiling glare with the benefits of high resolution, high detective quantum efficiency (DQE), high frame rate and high dynamic range, small image lag (< 1%), and excellent linearity (approximately 1%). The advantages of the new FPD make it a promising candidate for cone-beam volume computed tomography (CT) angiography (CBVCTA) imaging. The purpose of this study is to characterize a prototype FPD-based imaging system for CBVCTA applications. A prototype FPD-based CBVCTA imaging system has been designed and constructed around a modified GE 8800 CT scanner. This system is evaluated for a CBVCTA imaging task in the head and neck using four phantoms and a frozen rat. The system is first characterized in terms of linearity and dynamic range of the detector. Then, the optimal selection of kVps for CBVCTA is determined and the effect of image lag and scatter on the image quality of the CBVCTA system is evaluated. Next, low-contrast resolution and high-contrast spatial resolution are measured. Finally, the example reconstruction images of a frozen rat are presented. The results indicate that the FPD-based CBVCT can achieve 2.75-lp/mm spatial resolution at 0% modulation transfer function (MTF) and provide more than enough low-contrast resolution for intravenous CBVCTA imaging in the head and neck with clinically acceptable entrance exposure level. The results also suggest that to use an FPD for large cone-angle applications, such as body angiography, further investigations are required.

MR volumetric analysis of the human basal ganglia: normative data

RATIONALE AND OBJECTIVES

The authors undertook this study to identify a precise, semiautomated, reproducible magnetic resonance (MR) imaging technique for measuring the basal ganglia, to establish normative volumetric data, and to verify the presence of previously reported asymmetries.

MATERIALS AND METHODS

Twenty-eight healthy adults underwent cranial MR examination. The volumes of the various components of the basal ganglia were measured by means of a combination of thresholding and manual tracing techniques performed with specialized software. The validity of these measurements was assessed by fashioning, imaging, and measuring a practical basal ganglia phantom. Measurement accuracy was also established by means of inter- and intrarater reliability indexes. Normalized volumes were statistically analyzed with analysis of variance and paired t tests.

RESULTS

The absolute values of the various components of the basal ganglia varied widely even though the volumes were normalized to differences in intracranial volume. The right caudate nucleus volume was significantly (P < .000001) larger than the left in both men and women and in both right-handed and non-right-handed subjects. This asymmetry led to an increase in the overall volume of the basal ganglia on the right.

CONCLUSION

The authors have defined a precise, reproducible technique for measuring various components of the basal ganglia and have established normative data. The basal ganglia, similar to other brain structures, exhibit hemispheric lateralization.

A cone-beam reconstruction algorithm for circle-plus-arc data-acquisition geometry

In cone-beam computerized tomography (CT), projections acquired with the focal spot constrained on a planar orbit cannot provide a complete set of data to reconstruct the object function exactly. There are severe distortions in the reconstructed noncentral transverse planes when the cone angle is large. In this work, a new method is proposed which can obtain a complete set of data by acquiring cone-beam projections along a circle-plus-arc orbit. A reconstruction algorithm using this circle-plus-arc orbit is developed, based on the Radon transform and Grangeat's formula. This algorithm first transforms the cone-beam projection data of an object to the first derivative of the three-dimensional (3-D) Radon transform, using Grangeat's formula, and then reconstructs the object using the inverse Radon transform. In order to reduce interpolation errors, new rebinning equations have been derived accurately, which allows one-dimensional (1-D) interpolation to be used in the rebinning process instead of 3-D interpolation. A noise-free Defrise phantom and a Poisson noise-added Shepp-Logan phantom were simulated and reconstructed for algorithm validation. The results from the computer simulation indicate that the new cone-beam data-acquisition scheme can provide a complete set of projection data and the image reconstruction algorithm can achieve exact reconstruction. Potentially, the algorithm can be applied in practice for both a standard CT gantry-based volume tomographic imaging system and a C-arm-based cone-beam tomographic imaging system, with little mechanical modification required.

Image intensifier-based computed tomography volume scanner for angiography

RATIONALE AND OBJECTIVES

A prototype volume computed tomography (CT) system for use in angiography was designed, constructed, and tested. The system consisted of a fixed X-ray tube, a conventional image intensifier (II) coupled to a charge-coupled device camera, and a computer-controlled turntable on which phantoms were placed. We wanted to predict, through phantom studies, the imaging performance of an II-based volume CT for direct three-dimensional (3D) reconstruction of vascular structures.

METHODS

To explore the imaging performance of the system for reconstructing a vascular structure, two sets of projection images of a vascular phantom, acquired over 250 projection angles with two different-sized IIs, were digitized and used for a direct 3D conebeam reconstruction. The signal-to-noise ratio (SNR) of each reconstructed image was measured. From these measurements, image quality was accessed as a function of the number of reconstructions averaged and the different orientations. The spatial resolution limits of the system were measured from the 3D reconstructed images of a specially designed resolution phantom for different orientations and locations.

RESULTS

The measured SNRs of all direct 3D reconstruction images were reasonably good, and back-ground noise levels measured from 3D reconstruction images were almost 30 Hounsfield units. The measured spatial resolution of the system was 0.5 line pairs per millimeter. However, spatial resolution was reduced around the edge of the II to nearly half that measured in the central area of the field of view.

CONCLUSION

An II-based volume CT scanner can produce direct 3D reconstructions of vascular structures with good image quality for intraarterial angiography.

Computer simulation of image intensifier-based computed tomography detector: vascular application

This present study reports the results of a computer simulation whose aim was to predict the low-contrast imaging performance of which a conventional x-ray image intensifier with charge coupled device (CCD) camera would be capable if incorporated into a computed tomography (CT) volume imager. A vascular imaging task was modeled in our simulation. The effects of detector noise, x-ray exposure levels, analog-to-digital conversion (ADC) precision and residual levels of detected x-ray scatter were considered. The results of this simulation indicate that the low-contrast imaging performance of an image intensifier-based CT system was most limited by the CCD detector readout noise. Given this limitation the detection of greater than about 100,000 detected photons/pixel/projection gave marginal improvement in low-contrast resolution. At these exposures 12 bit ADC precision resulted in little additional image noise. The effects of detecting scattered x rays are twofold; decreasing the signal-to-noise ratio associated with our modeled artery and introducing a cupping artifact. Based on the results from the simulation, it appears that an image intensifier-based CT system is a feasible concept from a noise viewpoint, if the anticipated imaging task is intravenous angiography.

Reconstruction of blood vessels from x-ray subtraction projections: limited angle geometry

Several algorithms have been investigated for reconstructing blood vessels from a limited number of x-ray subtraction projections, distributed over a limited range of angles. Both computer simulations and an in vivo animal study were carried out. The best reconstruction performance was achieved using an algorithm that folded in two pieces of a priori knowledge of the vascular density distributions: (1) the object is dilute, consisting mainly of a void; and (2) the density distribution in the reconstructions is most likely to be non-negative. Both the signal-to-noise ratio (SNR) and the signal to out-of-focus blur were quantitated. Compared to tomosynthetic reconstruction (backprojection), the amount of residual blur from out-of-focus planes was significantly reduced with only a small penalty in diminished SNR. The combined effect resulted in significant qualitative image improvement for real arterial distributions as demonstrated in a canine arterial imaging example.

Radioimmunoassay of the anticonvulsant agent clonazepam

A simple and specific radioimmunoassay was developed for the determination of the anticonvulsant agent clonazepam directly in plasma without extraction. Antibodies to clonazepam were produced in rabbits after immunization with an immunogen prepared by covalently linking the 3-hemisuccinyloxy derivative of clonazepam to bovine serum albumin. When employing 3H-clonazepam as the tracer, the radioimmunoassay has a limit of sensitivity of 5 ng/ml using a 0.1-ml sample of plasma. The antibodies exhibited a high degree of specificity for clonazepam; no cross-reactivity was observed with its 7-amino and 7-acetylamino metabolites nor with a number of other widely prescribed anticonvulsant agents that might be administered in conjuction with clonazepam. Satisfactory agreement was obtained for the plasma levels of clonazepam in humans when samples were assayed by the radioimmunoassay and an established electron-capture GC technique. By virtue ot its simplicity, the radioimmunoassay offers a distinct advantage to the clinician for monitoring plasma clonazepam levels and the compliance of patients undergoing anticonvulsant therapy with the drug.