浅谈胶体

高中化学选修教材的《胶体》一节,由于展开不够充分,使不少学生和教师难以把握相关内容,出现了一系列的模糊认识.我们把这些问题搜集起来,并根据我们的理解来谈一谈有关《胶体》的疑难问题.

Failure mechanisms and destruction characteristics of cemented coal gangue backfill under compression effect of non-uniform load

Backfill mining is one of the most important technical means for controlling strata movement and reducing surface subsidence and environmental damage during exploitation of underground coal resources. Ensuring the stability of the backfill bodies is the primary prerequisite for maintaining the safety of the backfilling working face, and the loading characteristics of backfill are closely related to the deformation and subsidence of the roof. Elastic thin plate model was used to explore the non-uniform subsidence law of the roof, and then the non-uniform distribution characteristics of backfill bodies’ load were revealed. Through a self-developed non-uniform loading device combined with acoustic emission (AE) and digital image correlation (DIC) monitoring technology, the synergistic dynamic evolution law of the bearing capacity, apparent crack, and internal fracture of cemented coal gangue backfills (CCGBs) under loads with different degrees of non-uniformity was deeply explored. The results showed that: 1) The uniaxial compressive strength (UCS) of CCGB increased and then decreased with an increase in the degree of non-uniformity of load (DNL). About 40% of DNL was the inflection point of DNL-UCS curve and when DNL exceeded 40%, the strength decreased in a cliff-like manner;2) A positive correlation was observed between the AE ringing count and UCS during the loading process of the specimen, which was manifested by a higher AE ringing count of the high-strength specimen. 3) Shear cracks gradually increased and failure mode of specimens gradually changed from “X” type dominated by tension cracks to inverted “Y” type dominated by shear cracks with an increase in DNL, and the crack opening displacement at the peak stress decreased and then increased. The crack opening displacement at 40% of the DNL was the smallest. This was consistent with the judgment of crack size based on the AE b-value, i. e., it showed the typical characteristics of “small b-value-large crack and large b-value-small crack”. The research results are of significance for preventing the instability and failure of backfill.

介绍新编教科书《胶体与界面化学》

简要介绍了《胶体与界面化学》一书的内容、特点 。

Preparation and characterization of ZrO_2/TiO_2 composite photocatalytic film by micro-arc oxidation

ZrO2/TiO2 composite photocatalytic film was produced on the pure titanium substrate using in-situ Zr（OH）4 colloidal particle by the micro-arc oxidation technique and characterized by scanning electron microscope （SEM）, energy dispersive X-ray （EDX）, X-ray diffraction （XRD） and ultraviolet-visible （UV-Vis） spectrophotometer. The composite film shows a lamellar and porous structure which consists of anatase, futile and ZrO2 phases. The optical absorption edge of film is shifted to longer wavelength when ZrO2 is introduced to TiO2. Furthermore, the photocatalytic reaction rate constants of degradation of rhodamine B solution with ZrO2/TiO2 composite film and pure TiO2 film under ultraviolet irradiation are measured as 0.0442 and 0.0186 h 1, respectively.

Application of face centred cubic TiB powder as conductive filler for electrically conductive adhesives

Face centred cubic（FCC） TiB ceramic powder synthesized by Ti-boronizing method was used as conductive filler to make ceramic electrically conductive adhesives（ECAs） with the polymer matrix.Electrically conductive properties of the ceramic ECAs were studied.The bulk electrical resistivity varied with the powder content of the FCC-TiB in ECAs.The FCC-TiB filled ECAs also showed the percolation behavior that usually occurred for the metal-filled ECAs,the percolation threshold was located at the content of 60%FCC-TiB.A minimum value of 0.1 Ω·cm was obtained at a content of 75%FCC-TiB.In order to check the reliability of mechanical property,tensile test was done to measure the shear strength,and the shear strength dropped with increasing the content of FCC-TiB powders.It is about 12.26 MPa at the content of 70%TiB powders.The Cu filled ECAs were also prepared for comparison.The properties of the oxidation resistance of the two ECAs were evaluated.The results show that the ceramic ECAs have excellent oxidation resistance and better stability compared with the Cu filled ECAs.

Bonding Performance of Wood Treatment by Oxygen and Nitrogen Cold Plasma

In the test, woods were treated by N2, O2 cold plasma with the processing power 300 W, which last for 5 min; subsequently, the treated woods were bonded with MUF to valve the bonding performance, the contact angles of the treated/un- treated wood were tested. The chemical composition on the surface of wood with or without N2 cold plasma treatment was also studied by X-ray photoelectron spec- troscopy （XPS）. The results showed： the contact angles of the surface decreased; the surface free energy increased evidently that treated by N2 or O2 cold plasma; the average bonding performance of wood that treated by cold plasma （whether N2 or O2） increased obviously and more than 50% was proved compared with that un- treated by cold plasma. The XPS analysis showed the atomic ratio O/C has in- creased, and more groups were oxidized or more peroxides were formed on the surface of wood; N element was introduced to the wood surface after nitrogen cold plasma treatment and it was estimated to the group of -NH2.

Effect of Cold Plasma on Binding Strength of Bamboo

[Objective] The paper was to study the effect of cold plasma on binding strength of bamboo. [Method] The bamboos were treated by 4 kinds of cold plasma nitrogen, oxygen, ammonia and argon, and the changes of contact angle and binding strength of bamboos before and after treatment were tested. [Result] Oxygen cold plasma treatment could increase binding strength of bamboo by 25%-30%. The cold plasma treatment was very fast and effective, but the changes of contact angle was not great in this experiment. [Conclusion] Cold plasma treatment could increase the binding strength of bamboo.

Damage failure of cemented backfill and its reasonable match with rock mass

In order to study the failure mechanism of backfill and the reasonable matches between backfill and rock mass, and to achieve the object of safe and efficient mining in metal mine, four types of backfills were tested under uniaxial compression loading, with cement?tailing ratios of 0.250:1, 0.125:1, 0.100:1 and 0.083:1, respectively. With the help of the stress?strain curves, the deformation and failure characteristics of different backfills with differing cement?tailing ratios were analyzed. Based on the experimental results, the damage constitutive equations of cemented backfills with four cement?tailing ratios were proposed on the basis of damage mechanics. Moreover, comparative analysis of constitutive model and experimental results were made to verify the reliability of the damage model. In addition, an energy model using catastrophe theory to obtain the instability criteria of system was established to study the interaction between backfill and rock mass, and then the system instability criterion was deduced. The results show that there are different damage characteristics for different backfills, backfills with lower cement?tailing ratio tend to have a lower damage value when stress reaches peak value, and damage more rapidly and more obviously in failure process after peak value of stress; the stiffness and elastic modulus of rock mass with lower strength are more likely to lead to system instability. The results of this work provide a scientific basis for the rational strength design of backfill mine.

Single Polar Compound Bioelectret Material and Its Influence on the Cell Growth

To explore the influence of compound bioelectret material′s dielectric property on the cell growth,several kinds of compound bioelectret materials of collagen/chitosan were developed Their TSDC(thermally stimulated depolarization current)spectra were analyzed,and the compound bioelectret collagen/chitosan whose t α and I α were 37℃ and 2×10 -9 A respectively at polarized state was selected The cell culture study showed that the compound bioelectret material could promote normal cell growth when singly negatively polarized,and could inhibit cancer cell growth when singly positively polarized It proves that the rational designation of compound bioelectret has a broad application for clinical medicine

Radionuclide Colloid ^(32)P Used for the Treatment of Stage II Lung Cancer by Video Enhanced Minimal Access Muscle Sparing Thoracotomy

Objective: To study the feasibility of radionuclide colloid 32P used for the treatment of stage II lung cancer by video enhanced minimal access muscle sparing thoracotomy (VEMAST). Methods: Video assisted thoracoscopic surgery (VATS) was carried out under general anesthesia. A double lumen endobronchial tube was intubated into trachea. One lung ventilation of the healthy side was done during operation. An incision of 8–10 cm long was made along the 4th or 5th intercostals. The lobectomy could be performed under VATS. Radionuclide colloid 32P was injected locally into the area where surgical cleaning of lymph node around was considered to be unsatisfactory or desection of the tumor was not completed. Results: The operation with VEMAST was successful in 29 patients. A conventional lobectomy by thoracotomy had to be done due to unusual bleeding from the pulmonary artery involved during VEMAST in one case and the procedure was interrupted because the pulmonary artery cloud not be separated from the tumor in another patient. There was no dead case or the patient who had any severe complication or adverse response to the radiant. Conclusion: Radionuclide therapy was performed to the treatment of stage II lung cancer with VEMAST in case that surgical resection was considered not to be satisfactory. Minithoractomy assisted with VATS lobectomy and radionuclide colloid 32P therapy is a safe and e?ective technique for some selected stage II lung cancer.

Study on ternary polymerization of toluene diisocyanate

For the production of reactive polyurethane cross-linkinger and curing agents, 2, 4-diisocyanate toluene （TDI） terpolymer, which possesses the rigid structures of hexatomic ring and three reactive functional groups, was synthesized and characterized by the Fourier transform infrared （FFIR）, the gel permeation chromatography （GPC） and the chemical analysis methods. The reaction conditions were studied and optimized. A tracking research on the polymerization process of TDI was taken by using the GPC. The formation processes of the terpolymer, oligomers and higher-polymers were also dealt with. Results show that the TDI terpolymer can be prepared in the presence of Cat-3 catalyst and at the reaction temperature of （60 ±2）℃. The reaction time is short, its outcomes have narrow molecular weights distribution, namely molecular weights from 530 to 550, Mw/Mn =1.10, and the mass fraction of NCO is （25. 0 ± 0. 5）%. With the reaction time prolonging, however, TDI can be further higher-polymedzed to form higher-polymers. Benzoyl chloride （0. 4%, mass fraction）, as the stabilizing agent, can effectively inhibit the occurrence of higher-polymerization. The obtained TDI terpolymer can be stable for more than half a year.

Establishment of a Collection and Detection Technology of Mycoplasma hyopneumoniae in Aerosol

ObjectiveThis study was to establish a simple method for collecting and detecting Mycoplasma hyopneumoniae （Mhp） in aerosol. MethodBased on the mechanisms of liquid impinger and filtration sampler, a double concentration aerosol sampler was designed for collecting Mhp aerosol. Firstly, the collection was performed in a closed environment full of artificial aerosol of Mhp. Secondly, collection efficiency was detected by real-time PCR. Thereafter, the clinical feasibility of the designed equipment was tested by collecting aerosol samples in different pig herds. In one assay, the samples were collected at different times from one pig house challenged with Mhp. In another assay, the samples was collected from the delivery room, nursery and fattenning house of a MPS outbreak farm as well as a Mhp infection positive pig farm without obvious clinical symptoms. All the aerosol samples were then detected by real-time PCR or nested PCR. ResultThe collection efficiency of the designed bioaerosol sampler was （37.04±6.43） %, Mhp could be detected 7 d after intratracheal challenge with pneumonic lung homogenate suspension. Aerosol samples of 11 pig houses from the two Mhp positive pig farms with or without clinical symptoms all showed a positive result of PCR, the positivity rate was 100%. ConclusionA high sensitive collecting and detecting technology of aerosol was successfully established, which can be applied to clinical detection of Mhp in aerosol.

The Study of Dipivefrin Hydrochloride Ophthalmic Gel

Dipivefrin hydrochloride ophthalmic gel was prepared and the release test and the isolated cornea permeation test of the formulation in vitro were investigated. The release test of the formulation was studied by using permeable membrane. The content and the release amount of Dipivefrin hydrochloride from the gel base were measured by high performance liquid chromatography. The cornea permeation test of the formulation was studied by using isolated rabbit corneas. The formulation release behavior in vitro followed the first-order kinetic equation. The release amount of Dipivefrin hydrochloride raised significantly with less polymer in the formulation. The cornea permeation behavior of the drug in vitro followed the first-order kinetic equation. The eye irritancy of Dipivefrin hydrochloride gel is lower than that of eyedrops.

Liquid drying of BeO gelcast green bodies using ethanol as liquid desiccant

BeO gelcast green bodies were dried by liquid drying method with liquid desiccant ethanol.Effects of ethanol concentration,solids loading and aspect ratio of green body on the moisture and shrinkage of green bodies were studied through measuring mass and dimension.Additionally,liquid drying stress was analyzed and a model of the initial stage drying stress was established.The results show that higher ethanol concentration,lower solids loading and higher aspect ratio of gelcast green bodies increase the drying rate.Increasing the ethanol concentration decreases the shrinkage rate.Liquid drying stress is generated due to a non-uniform drying rate.During the process of liquid drying,the inner drying stress of the green body changes from compressive stress to tensile stress,while the outer drying stress changes from tensile stress to compressive stress.

Preparation of liposomal fluconazole gel and in vitro transdermal delivery

Aim Liposomal fluconazole gel was prepared and its properties were studied. Methods The fluconazole liposomes were prepared by film dispersion method. Their shapes and sizes were observed by transmission electronic microscope and particle size analyzer, respectively. The skin permeation of liposomal gel was studied on rat skin by permeation cell. Results The entrapment efficiency of flueonazole liposomes was 47.68%. The fluconazole liposomes were oval or round in shape, and their average diameter was 250 ± 8 nm. The accumulative skin permeation of liposomal fluconazole gel （25.27%） was lower than that of non-liposomal fluconazole gel （36.72%）, but fluconazole retained in rat skin of liposomal gel （162 ± 15 μg·cm^-2） was higher than that of nonliposomal gel （48 ± 6μg·cm^-2）. Conclusion Liposomal fluconazole gel can significantly increase the deposited amounts of fluconazole in rat skin and it may be beneficial for topical use.

Molecular Cloning and Bioinformatical Analysis of a cDNA Encoding Mitochondrial 50S Ribosomal Protein L21 from Hevea brasiliensis Muell. Arg.

[Objective] ＂Tapping panel dryness （TPD）＂, a syndrome known as tapping incision blocked partly or entirely during latex exploiting, has become the most important factor causing great losses for rubber production. Aiming to elucidate the molecular mechanism of tapping panel dryness occurrence, this study carried out molecular cloning and bioinformatical analysis of a mRPL21 cDNA sequence, a gene associated with TPD. [Method] In a preliminary study, an expressed sequence tag （EST） encoding a deduced protein homologous to mitochondrial 50S ribosomal protein L21 （mRPL21）, which showed to be down-regulated in the latex of TPD-affected rubber trees, was isolated by suppression subtractive hybridization （SSH）. After ESTs assembling and RT-PCR validation, an 853 bp cDNA sequence with an open reading frame （ORF） was cloned, which was named as HbmRPL21 under GenBank accession number of HM230670. [Result] Bioinformatical analysis suggests that HbmRPL21 encodes a deduced polypeptide of 271 amino acids with a theoretical molecular weight （Mw） of 30.52 kDa and isolectric point （pI） of 8.40, and HbmRPL21 is a mitochondrion-targeted protein with a conserved domain of Ribosomal_L21p involving translation. Homology analysis reveals high amino acid sequence identity of mRPL21 from plants, while diversity of that between plant and animal kingdom. [Conclusion] This study laid the basis for further revealing the biological functions of mRPL21 in TPD-affected rubber trees.