Potential environmental and human health menace of spent graphite in lithium-ion batteries.

The growing demand for lithium-ion batteries for portable electronics and electric vehicles results in a booming lithium battery market, leading to a concomitant increase in spent graphite. This research investigated the potential impacts of spent graphite on environmental and human health using standardized toxicity extraction and Life Cycle Impact Assessment models. The spent graphite samples were classified as hazardous waste due to the average nickel content of 337.14 mg/L according to Chinese regulations. Besides, cadmium and fluorine were the other elements that exceeded the regulations threshold. Easily ignored aluminum and heavy metal cobalt are other harmful elements according to the results of Life Cycle Impact Assessments. All the metallic harmful elements mainly exist in a transferable state. Thermogravimetry infrared spectrometry coupled with mass spectrometry was employed to recognize the emitted gases and explore gas emission behavior. Inorganic gases of CO, H2S, SO2, SO3, oxynitride, HCl, and fluoride-containing gases were detected. Sulfur-containing gases released from spent graphite were contributed by the residual sulfuric acid after leaching. The correlation between the evolution of emitted gases and the heating schedule was established simultaneously. The research comprehensively illustrates the pollution of spent graphite and provides assistance for the design of green recycling schemes for spent graphite.

Amino-functionalized Cu metal-organic framework nanosheets as fluorescent probes for detecting TNP.

Here, we report a simple and benign method to successfully fabricate amino-functionalized Cu metal-organic framework (NH2-Cu-MOF) nanosheets. After synthesizing Cu2O nanocubes, they were mixed with organic ligand 2-aminoterephthalic acid (NH2BDC) solution at room temperature for 4 hours to form NH2-Cu-MOF nanosheets. Interestingly, the prepared NH2-Cu-MOF nanosheets have ultra-thin thickness, directional growth characteristics and excellent crystallinity. Moreover, such nanosheets showed high-intensity and high-stability fluorescence emission under excitation. As TNP in water can quench the fluorescence emission of the fluorescent probe, the NH2-Cu-MOF nanosheet fluorescent probe was established for detecting TNP in water with high sensitivity and selectivity, which is very useful for assessing the environmental quality and safety of water bodies. Finally, the probe was used to detect TNP in actual samples with good recovery rate.

Tetracycline antibiotics and NH4+ detection by Zn-organic framework fluorescent probe.

A fluorescent probe based on single metal-organic framework material without additional fluorophores and active sites can significantly improve the stability of the probe for detection, and has very important application value in environmental analysis and detection. In this paper, a simple and rapid fluorescence detection method was established with Zn-MOF, which realized the highly sensitive detection of tetracycline antibiotics and NH4+ in water. The prepared Zn-MOF has abundant pores and can exist stably in water. When tetracycline antibiotics are present in Zn-MOF aqueous solution, based on the unique coordination ability between Zn and N, tetracycline antibiotics rich in N will be adsorbed into the pore canals of MOF, and aggregation-induced luminescence will occur. The original non-fluorescent Zn-MOF will immediately produce yellow fluorescence, realizing the detection of tetracycline antibiotics in water, with the limit of detection reaching 0.017 µM in a linear range of 0.02-13 µM. Zn-MOF is further used for the detection of tetracycline antibiotics in actual samples of milk and honey. Oxytetracycline (OTC) with the best fluorescence response of tetracycline antibiotics was coated on Zn-MOF to synthesize OTC@Zn-MOF fluorescent probe. NH4+ will replace the original ligand of Zn-MOF, which will disintegrate MOF and release OTC, resulting in a fluorescence decrease. Therefore, NH4+ can be detected with low limit of detection (0.038 µM) in a linear range of 0 to 3 mM. The probe is expected to be able to detect ammonia in the environment.

N-doped MoS2-nanoflowers as peroxidase-like nanozymes for total antioxidant capacity assay.

Total Antioxidant Capacity (TAC) Assay plays an important role in evaluating the quality of antioxidant food and monitoring the oxidative stress level of human body. It is mainly achieved by measuring the contents of antioxidants such as AA, L-Cys and GSH, while TAC can be detected by using peroxidase-like activity of artificial nanoenzyme materials. In this work, the N-Doped, defect-rich N-MoS2NFs nano-materials were used to build the nano enzyme, which has strong stability and high peroxidase-like activity. H2O2 was detected because it can be catalyzed to generate the intermediate ·OH and make TMB appears blue. However, when H2O2, AA, L-Cys and GSH coexist in solution, due to the oxidation resistance of AA, L-Cys and GSH, they can competitively react with ·OH in solution or reduce TMB in oxidation state (oxTMB), which reduces the characteristic absorption of oxTMB, indirectly achieves the purpose of detecting AA, L-Cys and GSH, and finally realizes the determination of TAC, even in actual serum and saliva samples. At the same time, the N-MoS2 NFs/NH2-MIL-53(Al)+OPD system is further constructed. Based on the fluorescence resonance energy transfer (FRET) between NH2-MIL-53(Al) and oxidized OPD (oxOPD), the purpose of detecting TAC by fluorescence method was realized.

Detection of hydrogen peroxide and glucose with a novel fluorescent probe by the enzymatic reaction of amino functionalized MOF nanosheets.

Amino-functionalized two-dimensional (2D) MOFs have great potential in biosensors due to their excellent water solubility, high fluorescence, large specific surface area, good adsorption properties and good ability to enrich the target analytes. Fluorescence detection of hydrogen peroxide and glucose mostly relies on monitoring the single fluorescence intensity changes in a single excitation wavelength. Here, a ratiometric fluorescence sensor based on NH2-MIL-53(Al) nanosheets to sensitively detect H2O2 and glucose through enzymatic reactions was developed. o-Phenylenediamine (OPD) was oxidized by H2O2 in the presence of horseradish peroxidase (HRP). Then, the oxidation product could be self-assembled on NH2-MIL-53(Al) nanosheets by hydrogen bonding and π-π stacking. The orbital interaction or the fluorescence resonance energy transfer (FRET) between the nanosheets and the oxidation product could effectively quench the fluorescence of the nanosheets at 433 nm. At the same time, the oxidation product provided a new emission peak at 564 nm. The fluorescence ratio signal changes generated by this oxidation process were used to stably and sensitively detect H2O2 and glucose. Structural and mechanistic analysis was carried out by calculation methods such as AICD and ORCA to explore the π electron structure characteristics, the hole/electron orbitals and the quenching phenomenon. The detection limit was 26.9 nM for H2O2 and 0.041 µM for glucose. The detection of glucose in human serum has a satisfactory recovery of 97.4-102.8%. It is clear that the sensor has a good application prospect in real sample analysis.

Ratio fluorescence detection of tetracycline by a Eu3+/NH2-MIL-53(Al) composite.

Tetracycline detection has been a great concern because of its overuse and difficulty in degrading. Here, a detection method with ratio fluorescence was developed by synthesizing Eu3+ doped nanocomposites with NH2-MIL-53(Al) nanosheets. After adding tetracycline, the fluorescence intensity at 616 nm characteristic emission peak of Eu3+ was sensitized by the antenna effect generated from coordinating Eu3+ with tetracycline, but the fluorescence of NH2-MIL-53(Al) at 433 nm was quenched by the fluorescence resonance energy transfer between the Eu3+-tetracycline composition and NH2-MIL-53(Al). Therefore, the efficient detection of tetracycline was achieved based on this change of ratio fluorescence signal. The experimental results show that Eu3+/NH2-MIL-53(Al) has excellent selectivity, a wider linear range and a lower detection limit for detecting tetracycline. This method can afford favorable ideas for developing advanced chemical and biological sensors.

Changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery.

PURPOSE: To evaluate changes in cerebral hemodynamics after carotid stenting of symptomatic carotid artery in the patients who underwent ischemic stroke caused by carotid artery stenosis. METHODS: Twenty patients with unilateral symptomatic carotid artery stenosis received brain computer tomography perfusion (CTP) scan a week before and a week after carotid artery stenting. Three absolute values including mean transit time (MTT), cerebral blood volume (CBV), and cerebral blood flow (CBF) were acquired and analyzed by use of the post-processing software. Six vascular territories such as ACA territory, MCA territory, PCA territory, basal ganglia, watershed between ACA and MCA territory (frontal watershed), watershed between MCA and PCA territory (posterior watershed) were chosen for comparison. Relative parameter values were defined as rCBF (relative CBF), rCBV (relative CBV), rMTT (relative MTT) through comparing absolute values in symptomatic hemispheres to absolute values in asymptomatic hemispheres. The relative perfusion parameter values before treatment were compared with post-treatment values. These analyses were performed by using the paired t test. RESULTS: The mean rMTT decreased significantly in ACA territory, MCA territory and two watershed after treatment, while the mean rCBF increased significantly in those areas after treatment. But the mean rCBV had no significant changes in all six vascular territories. In PCA territory, all the parameters had no significant changes. CONCLUSION: Carotid artery stenting yields satisfactory cerebral perfusion in ACA territory, MCA territory, basal ganglia and two watersheds.

Evaluation of multislice computed tomographic perfusion imaging and computed tomographic angiography on traumatic cerebral infarction.

OBJECTIVE: To evaluate the application value of multislice computed tomographic perfusion imaging (MSCTPI) and multislice computed tomographic angiography (MSCTA) on traumatic cerebral infarction. METHODS: MSCTA was performed on 10 patients who were initially diagnosed as traumatic cerebral infarction by normal conventional computed tomography (NCCT), among whom, 3 patients were examined by MSCTPI simultaneously. Reconstructed images of the intracranial artery were made with techniques of maximum intensity projection (MIP) and volume rendering (VR) from MSCTA scanning data. Then the graph of function of four parameters, regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), mean transit time (MTT), and time to peak (TTP), acquired by the perfusing analysis software was obtained. RESULTS: Among the 10 patients with traumatic cerebral infarction, 6 showed complex type on NCCT, which depicted abnormality on MSCTA, and 4 showed simple type on NCCT, which had negative results on MSCTA. Among the 4 patients with abnormal great vessels, 2 suffered from stenosis or occlusion of the middle cerebral artery, 1 from spasm of the anterior cerebral artery, and 1 from spasm of the vertebral-basal artery. The image of MSCTPI of 1 patient with massive cerebral infarction on the right cerebral hemisphere confirmed by CT was smaller than those of the other patients, which showed occlusion of the ipsilateral middle cerebral artery on MSCTA. Among the 6 patients whose MSCTA showed no abnormality, 4 showed simple infarction and 2 showed complex infarction. The infarction focus of 5 patients occurred in the basal ganglia and 1 in the splenium of corpus callosum. Among the 2 cases of small cerebral infarction volume on NCCT, one was normal, the other showed hypoperfusion on MSCTPI and was normal on MSCTA. CONCLUSION: The combination of MSCTPI and MSCTA is very useful for evaluating the change of intracranial artery in ischemic regions and assessing the cerebral hemodynamic information of traumatic cerebral infarction.

Identification and classification in le fort type fractures by using 2D and 3D computed tomography.

OBJECTIVE: To evaluate the usefulness of two- dimensional (2D) and three-dimensional (3D) computed tomography (CT) in the identification and classification of Le Fort type fractures. METHODS: Sixty-two patients with different types of Le Fort fractures underwent CT scanning and 3D-CT reconstruction. The data were analyzed by multiplanar reconstruction (MPR), surface shaded display (SSD) and volume rendering (VR) respectively. RESULTS: The patients with Le Fort I, Le Fort II fracture and Le Fort III fracture accounted for 16.1%, 14.5% and 12.9% respectively. The compound fractures were the most common type and accounted for 56.5% (n=35, 18 cases with Le Fort I+II fracture, 10 cases with Le Fort II+III fracture and 7 cases with Le Fort I+ II+III fracture). Fifty-five cases coexisted with other fractures in maxillofacial region. 2D-CT could be used to define the tiny fractures and the deep-structure fractures more accurately compared with 3D-CT, but the real impression of Le Fort type fractures could not be correctly evaluated on 2D-CT. 3D-CT could clearly demonstrate the whole shape of Le Fort type fractures and identify the classification of Le Fort fractures. CONCLUSIONS: 3D-CT is the best imaging method for the diagnosis of Le Fort type fractures and can provide valuable information of space relationship, especially for the design of treatment plan before operation.