Targeted improvement of narrow micropores in porous carbon for enhancing trace benzene vapor removal: Revealing the adsorption mechanism via experimental and molecular simulation.

Porous carbon materials are highly desirable for removing benzene due to their low energy for capture and regeneration. Research has demonstrated that narrow microporous volume is crucial for effective adsorption of benzene at ultra-low concentration. Unfortunately, achieving directional increase in the narrow microporous volume in porous carbon remains a challenge. Here, nitrogen-doped hydrothermal carbon was prepared using urea-assisted hydrothermal method, and then porous carbon (PUC800) was prepared by KOH activation. The resulting material had 180 % higher pore volume and 179 % higher surface area compared to non-nitrogen activation methods. Then, using mechanochemical (mechanical compaction and KOH activation) approach to produce PUC800-3T, which had a 30 % increase in pore volume and a 33 % increase in surface area compared to PUC800. PUC800-3T showed benzene adsorption capacity of 4.2 mmol g-1 at 1 Pa and 5.8 mmol g-1 at 5 Pa. Experimental and molecular simulation indicate that the benzene adsorption at 1 and 5 Pa is determined by pore volume of less than 0.8 and 0.9 nm, respectively. Density functional theory calculations provided insight into the CH⋯X (X = N/O) interactions drive benzene adsorption on the carbon framework. This work provides valuable theoretical and experimental support for designing, preparing, and applying adsorbents for trace removal of benzene vapor.

Enhanced ability of toluene oxidation by controlling inversion degree of spinel composed of only Co, Mn.

Exploring the single relationship between the inversion degree of spinel and its catalytic performance is a great challenge, but has important significance for further structural design and application. A series of CoMn inverse spinels were prepared and the general formula [Formula: see text] was deduced through X-ray diffraction refinement to find a decreased inversion degree x as calcination temperature rose. Catalytic oxidation of toluene showed that higher inversion degree (S-300 with x ≈ 0.95) can reach larger conversion rate (90 % at about 250 °C for 400 ppm toluene) with greater reaction stability (140 h). Density Functional Theory (DFT) calculations on density of states indicated its metallic nature, and found that the strength of O-p and Transition metal-d orbitals at Fermi energy is positively correlated to the inversion degree, meaning stronger electron migration ability. Along with the adsorption calculation analysis that lattice oxygen species are proved to work dominantly (S-300 with lowest adsorption energy but highest performance), this work uncovered a theoretical insight into inverse spinel oxide, to provide the possibility of elevated oxidation ability through structural control.

Revealing the Adsorption Mechanisms of Methanol on Lithium-Doped Porous Carbon through Experimental and Theoretical Calculations.

Previous reports have shown that it is difficult to improve the methanol adsorption performance of nitrogen and oxygen groups due to their low polarity. Here, we first prepared porous carbon with a high specific surface area and large pore volume using benzimidazole as a carbon precursor and KOH as an activating agent. Then, we improved the surface polarity of the porous carbon by doping with Lithium (Li) to enhance the methanol adsorption performance. The results showed that the methanol adsorption capacity of Li-doped porous carbon reached 35.4 mmol g-1, which increased by 57% compared to undoped porous carbon. Molecular simulation results showed that Li doping not only improved the methanol adsorption performance at low pressure, but also at relatively high pressure. This is mainly because Li-modified porous carbon has higher surface polarity than nitrogen and oxygen-modified surfaces, which can generate stronger electrostatic interactions. Furthermore, through density functional theory (DFT) calculations, we determined the adsorption energy, adsorption distance, and charge transfer between Li atom and methanol. Our results demonstrate that Li doping enhances the adsorption energy, reduces the adsorption distance, and increases the charge transfer in porous carbon. The mechanism of methanol adsorption by Li groups was revealed through experimental and theoretical calculations, providing a theoretical basis for the design and preparation of methanol adsorbents.

Experimental and theoretical calculations insight into acetone adsorption by porous carbon at different pressures: Effects of pore structure and oxygen groups.

The influence of different pore size and oxygen groups for porous carbons on acetone adsorption at different pressure was studied by using experimental data and theoretical calculation, and the results were applied to prepare carbon-based adsorbents with superior adsorption capacity. First, we successfully prepared five types of porous carbons with different gradient pore structure but similar oxygen contents (4.9 ± 0.25 at.%). We found that the acetone uptake at different pressure depends on the different pore sizes. Besides, we demonstrate how to accurately decompose the acetone adsorption isotherm into multiple sub-isotherms based on different pore sizes. Based on the isotherm decomposition method, the acetone adsorption at 18 kPa is mainly in the form of pore-filling adsorption in the pore size range of 0.6-2.0 nm. When the pore size is greater than 2 nm, the acetone uptake mainly depends on the surface area. Second, porous carbons with different oxygen content, similar surface area and pore structure were prepared to study the influence of oxygen groups on acetone adsorption. The results show that the acetone adsorption capacity is determined by the pore structure at relatively high pressure, and the oxygen groups only slightly increase the adsorption capacity. However, the oxygen groups can provide more active sites, thereby enhancing acetone adsorption at low pressure.

Blood transthyretin for predicting immunoglobulin A vasculitis nephritis outcome in children.

BACKGROUND: IgA vasculitis is characterized by inflammation of the blood vessels, which can result in microvascular destruction and consequently renal damage. Transthyretin is a newly discovered angiogenesis regulator in promoting microvascular regeneration. This indicates that transthyretin may act as a potential predictor of IgAV as well as IgAVN. METHODS: This retrospective study included 125 patients newly diagnosed as IgAV with demographic and laboratory parameters. Of these, 78 patients had demonstrated internal organ damage and 47 patients with only skin and joint injury. Of 78 patients with organ impairment, 27 were diagnosed of renal involvement. Then we evaluated the relationship between NLR, total protein, albumin, globulin, transthyretin, B lymphocyte counts and the severity of IgAV. RESULTS: For patients with internal organ or renal involvement, the level of transthyretin were lower than non-internal organ damage group (p < 0.001 for both group). Remarkably, the NLR was only higher in patients with internal organ damage group (p = 0.019). Logistic regression analysis showed that NLR and transthyretin both were risk factors for internal organ involvement (OR = 1.768, 0.973 separately), and only transthyretin is the independent risk for renal involvement (OR = 0.981, p < 0.05). The ROC analysis showed an AUC of 0.626 for NLR, 0.815 for transthyretin in predicting organ damage, 0.755 for transthyretin in patients with renal involvement (p < 0.05, to all parameters). CONCLUSIONS: Transthyretin is a better predictor in predicting internal organ or renal involvement than NLR, and low plasma transthyretin concentration can increase the risk of renal involvement in IgAV patients.

Let-7b regulates the adriamycin resistance of chronic myelogenous leukemia by targeting AURKB in K562/ADM cells.

Chronic myeloid leukemia (CML) is a malignant hematological disease, and drug resistance is often related to poor prognosis. MicroRNAs (miRNA) play a pivotal role in transcriptional regulation, cell development, and chemotherapy resistance. Here, we describe the effect of let-7b on resistant leukemia cells and examine the relevance of let-7b as a biomarker for adriamycin resistance. Results showed that let-7b was downregulated in K562/ADM (KA) cells, and the downregulation of let-7b in K562 and KA cells increased ADM resistance. The inhibition of let-7b subsequently induced the upregulation of AURKB. Finally, results proved that the Pi3k/Akt/Erk pathway was related to AURKB-activated resistance. Our research indicated that the underexpression of let-7b and overexpression of AURKB contributed to the resistance of CML, and its function is partly regulated by the Pi3k/Akt/Erk pathway. Thus, our further understand of its inhibitory effect may promise a new therapeutic strategy to overcome chemotherapeutic resistance in CML.

Insights into the Adsorption of VOCs on a Cobalt-Adeninate Metal-Organic Framework (Bio-MOF-11).

With increasingly severe air pollution brought by volatile organic compounds (VOCs), the search for efficient adsorbents toward VOC removal is of great significance. Herein, an adenine-based metal-organic framework, namely, bio-MOF-11 [Co2(ad)2(CH3CO2)2·0.3EtOH·0.6H2O, ad = adeninate], was synthesized via a facile method, and its VOC adsorption was reported for the first time. This novel bio-MOF-11 was investigated by employing four common VOCs (i.e., methanol, acetone, benzene, and toluene) as adsorbates. The saturated adsorption capacity of these targeted VOCs on bio-MOF-11 was estimated to be 0.73-3.57 mmol/g, following the order: toluene < benzene < acetone < methanol. Furthermore, with the adsorption temperature increasing from 288 to 308 K, the saturated adsorption capacity was reduced by 7.3-35.6%. It is worth noting that acetone adsorption is most sensitive to temperature ascribed to its low boiling point and strong polar nature. Meanwhile, owing to the molecular sieve effect, the adsorption capacity appears negatively correlated to the size of VOC molecules. Besides, the abundant exposed nitrogen atoms and amino groups in bio-MOF-11 cavities facilitate the adsorption of polar VOC molecules. This work promotes the fundamental understanding and practical application of bio-MOF for adsorptive removal of VOCs.

Catalytic performance of potassium in lignocellulosic biomass pyrolysis based on an optimized three-parallel distributed activation energy model.

The pyrolysis kinetics of extractive tobacco stem and pretreated samples with different KCl impregnation ratios were investigated by the thermogravimetric experiment and an optimized three-parallel distributed activation energy model (DAEM). The significant fitting deviation for the cellulose pyrolysis and the unrealistic partial fitting curve for the hemicellulose pyrolysis were mitigated during the optimization process by applying the Avrami-Erofeev-DAEM and reducing the latent interferences. The optimized parameters with good fitting qualities (about 2%) were obtained. Furthermore, based on the experimental results (changes in reaction intensity and temperature), model calculations (differences in reaction order, activation energy, volatiles fraction, etc.), and the maximum residual error analysis (with a high catalytic reaction rate) regarding different KCl-to-biomass ratios, it was found that KCl kinetically promoted the hemicellulose pyrolysis, which can be utilized as the theoretical support for the industrial application.

Highly Nitrogen-Doped Porous Carbon Derived from Zeolitic Imidazolate Framework-8 for CO2 Capture.

Setting the trap: A nitrogen-doped porous carbon, with a nitrogen content of up to 25.52 % and specific surface area of 948 m2 g-1 , exhibits a superior CO2 uptake of 3.7 mmol g-1 at 25 °C and 1 bar. Experimental and theoretical results indicate that the nitrogen-containing functional groups enhance CO2 uptake through electrostatic, Lewis acid-base, and hydrogen-bonding interactions.

TRIB2 knockdown as a regulator of chemotherapy resistance and proliferation via the ERK/STAT3 signaling pathway in human chronic myelogenous leukemia K562/ADM cells.

Acquired resistance to chemotherapy plays a critical role in human drug treatment failure in many tumor types. Multidrug resistance (MDR) to Adriamycin (ADM) also limits the efficacy of therapy in human chronic myelogenous leukemia (CML). The overexpression of drug efflux transporters is one mechanism uderlying MDR. In particular, the consistent activation of MDR1 and MDR­associated protein 1 (MRP1) is involved in drug resistance. In the present study, ADM­resistant human CML K562/ADM cells were stably transfected with a Tribbles homolog 2 (TRIB2)­targeted vector. A CCK­8 assay showed that the half maximal inhibitory concentration (IC50) of ADM and the cell proliferation were lower in the transfected cells compared with that in the parental K562/ADM cells. The mRNA and protein expression levels of MDR1 and MRP1 were determined by reverse transcription­polymerase chain reaction (RT­PCR), RT­quantitative PCR and western blot analysis. The results showed that the expression of MDR1 and MRP1 was significantly reduced in K562/ADM cells transfected with pGPU6/GFP/Neo­TRIB2. Due to the downregulation of MDR1 and MRP1, the intracellular accumulation of ADM was increased in the transfected cells compared with that in the parental K562/ADM cells. Therefore, the sensitivity of the K562/ADM cells to ADM was enhanced and proliferation was inhibited. Our research revealed that protein expression of the ERK signaling pathway was inhibited by downregulating TRIB2, indicating that the ERK pathway was involved in cell drug resistance and proliferation. Furthermore, we used the ERK­specific blocker U0126 to demonstrate this phenomenon. In summary, our research suggested that knockdown of TRIB2 could slow cell growth and reverse resistance, implying that TRIB2 is a potential therapy target for resistant human CML.

Nitrogen-Containing Functional Groups-Facilitated Acetone Adsorption by ZIF-8-Derived Porous Carbon.

Nitrogen-doped porous carbon (ZC) is prepared by modification with ammonia for increasing the specific surface area and surface polarity after carbonization of zeolite imidazole framework-8 (ZIF-8). The structure and properties of these ZCs were characterized by Transmission electron microscopy, X-ray diffraction, N2 sorption, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Through static adsorption tests of these carbons, the sample obtained at 600 °C was selected as an excellent adsorbent, which exhibited an excellent acetone capacity of 417.2 mg g-1 (25 °C) with a very large surface area and high-level nitrogen doping (13.55%). The microporosity, surface area and N-containing groups of the materials, pyrrolic-N, pyridinic-N, and oxidized-N groups in particular, were found to be the determining factors for acetone adsorption by means of molecular simulation with density functional theory. These findings indicate that N-doped microporous carbon materials are potential promising adsorbents for acetone.

Activated carbons modified by magnesium oxide as highly efficient sorbents for acetone.

Porous activated carbon modified with MgO was synthesized by an evaporation-induced self-assembly (EISA) method for its application to acetone capture. The textural and chemical characteristics of five modified activated carbon composites (AC-MgO) were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nitrogen adsorption isotherm measurements. The adsorption behaviors of samples for acetone were investigated and correlated to their physical and chemical properties. Density functional theory was also employed to calculate the charge transfer, the equilibrium distance, and the adsorption energy of acetone adsorbed on a carbon surface functionalized with crystalline MgO. An AC-MgO-10% sample with balanced surface area, microporosity and MgO content exhibited the highest acetone adsorption capacity (432.7 mg g-1). The results indicate that an appropriate MgO content on AC can effectively improve the adsorption capacity of acetone ascribed to strong chemisorption between MgO nanoparticles and acetone molecules.

[Serum resistin concentration and insulin resistance in obese children].

OBJECTIVE: Obesity is an important risk factor of insulin resistance and type 2 diabetes. Adipocyte is a cell that can actively secrete a series of factors to regulate the pathway responsible for energy balance. Resistin is one of these factors. The purpose of this study was to investigate possible correlation between resistin and certain parameters, including body parameters and other parameters of glucose metabolism and roles of resistin in hyperinsulinemia or insulin resistance in obese children. METHODS: The serum resistin concentration was measured in 34 obese children (18 boys, 16 girls; age 8.9-15.9 years) and 31 normal subjects (16 boys, 15 girls; age 7.8-14.5 years) by using ELISA. Anthropometric parameters, fasting glucose and insulin were measured in all subjects. Insulin resistance was assayed by homeostasis model assessment ratio (HOMA-R). Beta cell function was determined by using homeostasis model assessment beta cell (HOMA-beta). Correlation analysis was performed between resistin and other parameters. RESULTS: (1) The serum resistin concentration (common logarithmic transformation) was 3.1 +/- 0.5 in obese subjects and 2.7 +/- 0.8 in normal subjects. (P < 0.05). (2) The serum resistin concentration was not significantly correlated with sex, age, systolic and diastolic blood pressures, but was positively correlated with BMI, percent body fat (BF%), waist-hip ratio (WHR) (r = 0.299, r = 0.304, r = 0.322, P < 0.01); and positively correlated with fasting glucose, insulin, HOMA-R (r = 0.299, r = 0.303, r = 0.324, P < 0.05), but not significantly correlated with HOMA-beta. (3) Multiple linear regression analysis showed that only HOMA-R was the factor that significantly influenced resistin, R(2) = 0.105, the standard partial coefficient was 0.279 (P < 0.01). CONCLUSIONS: The serum resistin concentration in obese children were higher than that in normal children. The serum resistin concentration significantly correlated with the degree of obesity and the distribution of fat. Resistin is probably related to occurrence of hyperinsulinemia and/or insulin resistance in obese children.