海藻酸盐微胶囊及纳米Fe3O4的可控制备及应用的研究——介绍一个综合探究实验

介绍一个综合探究实验——制备海藻酸钙微胶囊和纳米Fe3O4,研究其吸附水中有机物和金属离子的效果。本实验与前沿接轨,能充分激发学生的学习兴趣,变被动学习为主动,有利于提升学生的综合探究能力。

Suppression of methane/air explosion by water mist with potassium halide additives driven by CO2

To enhance the explosion suppression effects of water mist, various potassium halide additives were tested in a confined vessel filled with a 10% mixture of methane/air. Air and CO2(0.7 MPa) were used as driver gases. The results revealed that halide additives exhibit considerable suppression effects on explosion overpressure. A30% KI mist decreased the explosion overpressure by 27.46% compared with the suppression by pure water mist under the same conditions. When CO2 is used as the driver gas, it will dissolve in water under high pressure.The synergistic effect of a CO2 solution with an effective additive afforded significant suppression. Under the same conditions, the overpressures suppressed by a mist of 30% KI + 0.7 MPa CO2 solution decreased by 33.53% compared with those suppressed by pure water mist driven by air. The synergistic suppression effect is much better than that of a 0.7 MPa CO2 solution mist or 30% KI mist alone. The multicomponent additives can be considered when suppressing methane/air explosions with pressure-formed water mist.

Effects of Solvent Molecules on the Interlayer Spacing of Graphene Oxide

Graphene oxide （GO） contains numerous functional groups that facilitate the intercalation of polar solvents. The properties and applications of GO are closely related to its interlayer spacing. We report on the changes in the interlayer spacing of GO after the adsorption of water molecules and the polar organic solvents C2H602 （EG）, C3HTNO （DMF）, C5H9NO （NMP）. Experiments were conducted to investigate the variations in the functional groups and structure of GO after solvent adsorp-tion, and they play a vital role in modeling and verifying the results of molecular dynamics simulation. The most stable GO structures are obtained through molecular dynamics simulation. The expansion of the interlayer spacing of GO after the adsorption of monolayer solvent molecules corresponds to the minimum three-dimensional size of the solvent molecules. The spatial arrangement of solvent molecules also contributes to the changes in interlayer spacing. Most adsorbed molecules are oriented parallel to the carbon plane of GO. However, as additional molecules are adsorbed into the interlaminations of GO, the adsorbed molecules are oriented perpendicular to the carbon plane of GO, and a large space forms between two GO interlayers. In addition, the role of large molecules in increasing interlayer spacing becomes more crucial than that of water molecules in the adsorption of binary solvent systems by GO.

Effects of the Imbibition Ability of Extinguishant in Pulverized Coals

The imbibition ability of extinguishant is an important factor influencing the extinguishing effect for smoldering fire in pulverized coals. The coal particle size, bulk compactness, and aqueous solution properties significantly affect the imbibition ability of extinguishment. This work aims to reveal the influence of the properties of pulverized coals and aqueous solution on the imbibition ability of extinguishant for smoldering fire through experiments and capillary theories. The imbibition height and rate were adopted to evaluate the imbibition ability of extinguishment. The results showed that a relatively small bulk compactness and a fine coal particle size negatively influenced the extinguishing process dominantly because of its high surface energy and low wettability. An additive was used to adjust the properties of aqueous solution. The liquid with a larger surface tension, a smaller contact angle, and a lower viscosity induced a better imbibition ability of extinguishment.

Influence of Na^+,K^+,Mg^(2+),Ca^(2+),and Fe^(3+) on filterability and settleability of drilling sludge

Solid–liquid separation is a vital step in drilling sludge disposal, and the filterability and settleability of drilling sludge are the main evaluating indicators for the separation process. The influence of Na^+,K^+,Mg^(2+),Ca^(2+),and Fe^(3+) on drilling sludge filterability and settleability was investigated in our research. The water content,filtration rate, supernatant volume and supernatant turbidity were measured to evaluate the filterability and settleability of drilling sludge. Meanwhile, the zeta potential, specific surface area of sludge flocs, particle size distribution and Fourier-transformed infrared spectra were employed to clarify the influencing mechanism.The experimental results showed that the filterability and settleability of drilling sludge were related to concentration and types of cations. Mg^(2+),Ca^(2+),and Fe^(3+) performed better than Na^+, K^+, and the cations with smaller hydrated radius got superior solid–liquid separation behavior at same valence. Finally, the spectra indicated that no chemical adsorption occurred between inorganic cations and drilling sludge flocs. The variation of surface charge and flocs growth after adding different inorganic cations were the reasons for the changes of the filterability and settleability.

Polybrominated Diphenyl Ethers in Surface Sediment from Songhua River Basin,Northeast of China

Sixty sediment samples were collected from the main Songhua River in three years. Twelve polybrominated diphenyl ether( PBDE) congeners( BDE17,28,47,66,99,100,153,154,138,183,and BDE-209) were detected to state the pollution situation. The results showed that the total concentration of total PBDEs ranges from 0. 424 to 23. 0 ng / g dry weight,with the mean of 3. 02 ng / g,and the total PBDEs concentration is at relative low level compared with those worldwide. The congener profile showed that BDE-209 is the dominant congener that accounts for more than 80. 1% of total PBDEs in sediments,followed by BDE-47 and BDE-99. These profiles are consistent with a high consumption of Deca-BDEs for the brominated flame retardant market in China. The results of spatial and seasonal observations indicated that local sources,temperature variation, and hydrologic conditions are significant factors on PBDEs concentrations. Hazard quotients suggested that PBDEs pose no potential risk to benthic organisms in detected area at present.

“Relay-mode”promoting permeation of water-based fire extinguishing agent in granular materials porous media stacks

Water-based fire extinguishing agent is the main means to deal with smoldering fires.However,due to the hydrophobic properties of the particle surface,the porous medium channel provide resistance and slow down the extinguishing agent flow during the downward permeation process.To promote the liquid permeation process in such porous media,this work studied liquid imbibition process and analyzed the oscillating and attenuating process of liquid level in capillary channel by theoretical,experimental,and numerical methods.An empirical mathematical equation was proposed to describe the oscillating process,and the effects of the capillary diameter and contact angle parameters on the transportation process were analyzed.Based on this,the“relay-mode”was proposed to promote the liquid transportation forward.Finally,the transient simulation results of liquid permeation in coal stacks showed when the liquid flowed through the channel with changed diameter from large to small ones,the transportation distance was several times longer than that through the unidiameter ones.The trend of liquid“relay-mode”in capillaries can be used to promote the permeation in granular materials porous media stacks.The relevant results also provide new thoughts to develop the water-based fire extinguishing agents and then improve the firefighting efficiency of deep-seated fire in porous media stacks.

Migration of Cr_2O_7^(2-) and Butanone in Soil and Groundwater System After the Tianjin Port 8·12 Explosion

After the Tianjin Port 8.12 explosion, an enormous amount of potassium dichromate （K2Cr2O7） and butanone （CH3COCH2CH3） leaked into the coastal soil-groundwater system, which potentially threatened the environment and human health. Determining the transport process of hazards is necessary to establish guidelines for remediating the contaminated area. This work aims to investigate the migration of potassium dichromate and butanone in the coastal soil-groundwater system through a coupling unsaturated-saturated numerical model, incorporating the HYDRUS model into the MODFLOW/ MT3D model. In the unsaturated zone, two-dimensional HYDRUS model was applied, and its recharge flux at the bottom boundary was utilized as the input of MODFLOW/MT3D model in the saturated zone. Results showed that Cr2O^（2-）7 migrated much faster than butanone in the unsaturated zone and reached the water table in about 1 year. In comparison, butanone was unlikely to enter the aquifer even 5 years later with a migration depth of about 2.2 m. Driven by groundwater, the Cr2O^（2-）7 that entered the aquifer migrated about 161 m toward southeast 5 years later. In the saturated zone, the contamination plume covered mainly the southeast area due to the groundwater flow direction.

Summary and Prospect of Treating Ulcerative Colitis by Warming the Kidney and Strengthening the Spleen

The method of warming the kidney and strengthening the spleen is widely used in the treatment of ulcerative colitis (UC) with significant curative effect.This paper reviews the relevant literature in recent years.

Streamlined and on-demand preparation of mRNA products on a universal integrated platform

Vaccines are used to protect human beings from various diseases.mRNA vaccines simplify the development process and reduce the production cost of conventional vaccines,making it possible to respond rapidly to acute and severe diseases,such as coronavirus disease 2019.In this study,a universal integrated platform for the streamlined and ondemand preparation of mRNA products directly from DNA templates was established.Target DNA templates were amplified in vitro by a polymerase chain reaction module and transcribed into mRNA sequences,which were magnetically purified and encapsulated in lipid nanoparticles.As an initial example,enhanced green fluorescent protein(eGFP)was used to test the platform.The expression capacity and efficiency of the products were evaluated by transfecting them into HEK-293T cells.The batch production rate was estimated to be 200–300μg of eGFP mRNA in 8 h.Furthermore,an mRNA vaccine encoding the receptor-binding domain(RBD)of the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)spike protein was produced by this platform.The proposed integrated platform shows advantages for the universal and on-demand preparation of mRNA products,offering the potential to facilitate broad access to mRNA technology and enable the development of mRNA products,including the rapid supply of new mRNA-based vaccines in pandemic situations and personalized mRNA-based therapies for oncology and chronic infectious diseases,such as viral hepatitis and acquired immune deficiency syndrome.

Activation of Pancreatic Acinar FXR Protects against Pancreatitis via Osginl-Mediated Restoration of Efficient Autophagy

Pancreatitis is the leading cause of hospitalization in gastroenterology,and no medications are available for treating this disease in current clinical practice.FxR plays an anti-inflammatory role in diverse inflammatory diseases,while its function in pancreatitis remains unknown.In this study,we initially observed a marked increase of nuclear FXR in pancreatic tissues of human patients ithpancratis eleting theFXRinpancreati acinar cels FXRicnara/a)ledto moreseverepancreatitis in mousemodels of caerulein-induced acute and chronic pancreatitis,while the FXR agonist GW4064 significantly attenuated pancreatitis in caerulein or arginine-induced acute pancreatitis and caerulein-induced chronic pancreatitis.FXR deletion impaired the viability and stress responses of pancreatic exocrine organoids(PEOs)in vitro.Utilizing RNA-seq and ChIP-seq of PEOs,we identified Osginl as a direct target of FxR in the exocrine pancreas,which was also increasingly expressed in human pancreatitis tissues compared to normal pancreatic tissues.Pancreatic knockdown of Osgin1 by AAV-pan abolished the therapeutic effects of FXR activation on pancreatitis,whereas pancreatic overexpression of Osginl effectively alleviated caerulein-induced pancreatitis.Mechanistically,we found that the FXR-OSGINl axis stimulated autophagic flux in the pancreatic tissues and cell lines,which was considered as the intrinsic mechanisms through which FXR-OSGINI protecting against pancreatitis.Our results highlight the protective role of the FXR-OSGIN1 axis in pancreatitis and provided a new target for the treatment of this disease.

Preparation and luminescence properties of orange-red Ba3Y4O9:Sm3+phosphors

A novel orange-red emitting Ba3 Y4 O9：Sm^（3＋） phosphors were prepared by a high temperature solidstate reaction in air. X-ray diffraction（XRD）, photoluminescence spectra, fluorescence decay and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties. The results show that the excitation spectrum includes a series of linear peaks at350, 367, 382, 410, 424, 445, 470 and 495 nm, respectively. Under 410 nm excitation, the emission peaks were located at 574 nm（~4 G（5/2）-~6 H（5/2））, 608 nm（~4 G（5/2）-~6 H（7/2））,659 nm（~4 G（5/2）-~6 H（9/2）） and722 nm（~4 G（5/2）-~6 H（11/2））, respectively. The concentration quenching occurs when x equals 0.08 for Ba3 Y（4-x）O9：xSm^（3＋） phosphor and its mechanism is ascribed to the dipole-dipole interaction. The chromaticity coordinates of Ba3 Y（3.92）O9：0.08 Sm^（3＋） phosphor are in the orange-red region. The temperature-dependent study shows that this phosphor has excellent luminescence thermal-stability.And the luminescence intensity of Ba3 Y（3.92）O9：0.08 Sm^（3＋） phosphor at 473 K only declines by about25.75% of its initial intensity. The experimental data indicate that Ba3 Y4 O9：Sm^（3＋） phosphor may be promising as an orange-red emitting phosphor for white light emitting diodes.

Nanoscale storage encryption: data storage in synthetic DNA using a cryptosystem with a neural network

Dear Editor,Synthetic DNA is emerging as a new data storage medium with high density and durable preservation capability potential(Ceze et al., 2019;Yazdi et al., 2015), thus enhancing the security of data stored in DNA is particularly important(Cherian et al., 2013;El-Zoghabi et al., 2013;Kalsi et al.,2018).

Unexpected activated carbon-catalyzed pyrrolo[1,2-a]quinoxalines synthesis in water

An interesting and recyclable activated carbon/water catalytic system for efficient synthesis of pyrrolo[1,2-a]quinoxaline derivatives was developed. The intramolecular C-N and C-C bond can be easily constructed in water under mild condition. This reaction features a broad substrate scope, a good tolerance to water and air, metal-free, additive-free and redox reagent-free.

Simulating multiphase flow in a two-stage pusher centrifuge using computational fluid dynamics

The design of two-stage pusher centrifuges have developed rapidly, but a good understanding of the theory behind their practice is a long-standing problem. To better understand centrifugal filter processes, the computational fluid dynamics （CFD） software program FLUENT has been used to model the three-dimensional geometry and to simulate multiphase flows based on Euler-Euler, moving mesh, dynamic mesh and porous media models. The simulation tangential velocities were a little smaller than those for rigid-body motion. In the stable flow region, the radial velocities were in good agreement with the theoretical data. Additionally, solid concentration distribution were obtained and also showed good agreement with the experimental data. These results show that this simulation method could be an effective tool to optimize the design of the two-stage pusher centrifuge.

Copper-catalyzed 1,1-difunctionalization of terminal alkynes: a three-component reaction for the construction of vinyl sulfones

A copper-catalyzed 1,1-difunctionalization of terminal alkynes was achieved via a three-component reaction, providing a variety of vinyl sulfones with good yields and excellent chemo-and stereoselectivity. Preliminary mechanistic studies indicated that the reaction probably underwent a Cu-catalyzed formal C–H insertion to produce an allene intermediate, which was then trapped by a sulfonyl anion to give the corresponding product.

Electrochemical synthesis of 3-azido-indolines from amino-azidation of alkenes

An electrochemical amino-azidation of 2-aminostyre ne with sodium azide(NaN3)was developed,which can be carried out smoothly in water under metal-free condition,affording a series of 3-azido indolines with high yields.

Endosulfan in the Chinese environment： monitoring and modeling

This paper reviews the usage and emissions of endosulfan, the newest member of the persistent organic pollutants （POPs）, in China, and its fate and behavior in Chinese environment. Endosulfan usage in China has been estimated to be approximately 25700 t between 1994 and 2004. Concentrations of endosulfan in different environ- mental compartments in China, such as air, soil, water, and biota, but focusing at air and surface soil, have been summarized. Concentrations of total endosulfan in surface soil across China were ranged from below detection limit （BDL） to 19000 pg.g^-1 dry weight （dw）, with geometric mean of 120pg.g^-1dw. The results indicated that endo- sulfan sulfate had highest concentration in Chinese soil, followed by r- and α-endosulfan. Air concentrations of endosulfan in China were ranged 0-340 pg.m3 for a- endosulfan and 0-121 pg. m--3 for β-endosulfan, with high concentrations occurred in the cotton production areas. Gridded usage inventories of endosulfan on a fine gridded system with a 1/4° longitude by 1/6° latitude resolution were compiled, from which, emission to air and residues in soil of endosulfan were calculated in each grid by using a modified simplified gridded pesticide emission and residue model （SGPERM）, an integrated modeling system combining mathematical model, database management system, and geographic information system. Total emissions were around 10800 t from 1994 to 2004. Based on the emission and residue inventories, concentrations of α- and β- endosulfan in Chinese air and agricultural surface soil were also calculated for each grid cell, which are in general consistent with the published monitoring data.