采用计算机辅助设计进行管/孔的布置

本文介绍了采用基于VisualLisp的二次开发 ,进行化工过程设备的主要部件设计 (板式塔塔盘孔和/或浮阀、换热器管板布管 )

文丘里管与孔板组合降解苯酚废水研究

利用水力空化技术,处理模拟废水苯酚,以文丘里管与不同的孔板组合作为空化装置。研究运行时间、入口压力、孔口排布方式及空化数对苯酚降解率的影响,并对苯酚降解的中间产物进行紫外-可见吸收光谱分析,初步判断降解过程中形成的产物性质。研究结果表明,随着时间的延长,苯酚的降解率先增大后趋于稳定,60 min时达到最大降解率;存在最佳入口压力,为0.4 MPa;孔口排布方式对苯酚降解率有较大影响。紫外-可见吸收光谱分析表明,苯酚降解过程的产物可能为酮类或醛类、苯二酚以及脂肪酸类物质。

Soil structure characters of different soil and water conservation plantations in typical black soil region

A study was conducted to determine the characters of soil structure in different water and soil conservation forests in Keshan County,northwest of Heilongjiang Province,China.The soil bulk density,the ratio of non-capillary porosity and capillary porosity（NCP/CP）,and the generalized soil structure index（GSSI） were measured for Fraxinus mandshurica,Larix gmelini,Pinus sylvestris var.mongolica,and Picea koraiensis plantations as well as the abandoned land（as control） adjacent to the forests in typical black soil region.Results show that at soil depth of 0–30cm,the soil bulk density of F.mandshurica forest and L.gmelini forest was lower than that of P.sylvestris var.mongolica forest and P.koraiensis forest,with the relative decrease of 8.04%–11.01%.The soil bulk density of L.gmelini forest was significantly different from that of the P.sylvestris var.mongolica forest and P.koraiensis forest.The NCP/CP values of the four types of plantations were all higher（59.75%–128.82% relatively） than that of abandoned land（p〈0.05）,indicating that the soil aeration and permeability under forest were enhanced,especially under L.gmelini forest.GSSI values of the four types of forests were also relatively higher（2.98%–4.36%） than abandoned land（p〈0.05）,indicating that those soil and water conservation forests,especially the F.mandshurica forest and P.koraiensis forest,can promote soil condition to approximate ideal soil structure.The result of this study can provide theoretical basis for scientifically evaluating the effects of vegetation restoration on soil quality in typical black soil region.

Pool boiling performance of porous surface tubes under vacuum conditions

Two types of tube bundles are designed,which are,respectively,composed of six tubes arranged in the boiling chamber.The nucleate pool boiling performance of smooth tube bundles and sintered porous surface tube bundles with deionized water as a medium are experimentally studied at atmospheric and sub-atmospheric pressures,respectively.The experimental results indicate that the boiling heat transfer coefficients of the two types of tube bundles increase with the increase in pressure under vacuum conditions as they behave under ordinary pressure.As the pressure varies from 10 to 100 kPa,it also can be seen that the heat transfer coefficient of the sintered porous surface tube is increased by 0.2 to 4 times compared with the smooth one under the same operating parameters.In addition,the experimental data show that a definite bundle effect exists in both sintered porous surface tubes and smooth tubes under vacuum conditions.

Wear mechanism and serious wear position of casing pipe in vertical backfill drill-hole

Vertical backfill drill-hole is usually a key project in an underground mine with backfill method and can be easily damaged by impact of backfill slurry.Observation of the damaged vertical backfill drill-holes in Jinchuan Nonferrous Metal Corporation（JNMC）,Gansu Province,China,given by a digital drill-hole video camera,indicated that there usually exist serious wear zones in casing pipe in vertical backfill drill-hole（CVBH）.It was suggested that serious wear position of CVBH should be located at an interface between air and solid-liquid mixture within CVBH.Backfill slurry falls freely and impacts the wall of CVBH near the interface with great momentum and energy coming from high speed free fall of backfill slurry.The depth of serious wear position of CVBH,i.e.,free fall height of backfill slurry in CVBH,can be estimated by the height of vertical backfill drill-hole,the length of horizontal pipeline,the density of slurry and the hydraulic gradient of pipeline system.A case study indicated that the estimation equation of serious damage depth of CVBH was of enough accuracy and was helpful for daily maintenance and management of vertical backfill drill-hole.

Design and fabrication of sintered wick for miniature cylindrical heat pipe

Miniature cylindrical metal powder sintered wick heat pipe （sintered heat pipe） is an ideal component with super-high thermal efficiency for high heat flux electronics cooling. The sintering process for sintered wick is important for its quality. The sintering process was optimally designed based on the equation of the heat transfer limit of sintered heat pipe. Four-step sintering process was proposed to fabricate sintered wick. The sintering parameters including sintering temperature, sintering time, sintering atmosphere and sintering position were discussed. The experimental results showed that the proper sintering temperature was 950 ℃ for Cu powder of 159μm and 900 ℃ for Cu powders of 81 and 38 μm, respectively, while the wick thickness was 0.45 mm and sintering time was 3 h. The optimized sintering time was 3 h for 0.45 and 0.6 mm wick thickness and 1 h for 0.75 mm wick thickness, respectively, when copper powder diameter was 159μm and sintering temperature was 950 ℃. Redox reduction reaction between H2 and CuO during sintering could produce segmentation cracks in Cu powders as a second structure. Sintering at vertical position can effectively avoid the generation of gap between wick and the inner wall of pipe.

Optimized DISA system parameters of a thin-wall malleable iron pipe casting by numerical simulation

The filling and solidification of a malleable iron pipe casting manufactured by DISA casting mold line with different design parameters were calculated by using software MAGMASOFT. Then the shrinkage porosity was predicted by thermal criterion. Based on the simulation results, the influences of the runner ratio and feeder position on the porosity were discussed. The results show that synchronization of injection can be significantly influenced by the size of downsprue section, and an de-sign structure of DISA gating system was used to solve the problem of flow imbalance in the filling procegs. At the same time, the riser was designed on the hotspot for feeding shrinkage. At last, the optimizated gating system and feeding system were ac-complished to eliminate shrinkage porosity.

Fabrication and photodegradation properties of TiO_2 nanotubes on porous Ti by anodization

Both Ti foil and porous Ti were anodized in 0.5%HF and in ethylene glycol electrolyte containing 0.5%NH4F(mass fraction) separately. The results show that TiO2 nanotubes can be formed on Ti foil by both processes, whereas TiO2 nanotubes can be formed on porous Ti only in the second process. The overhigh current density led to the failure of the formation nanotubes on porous Ti in 0.5%HF electrolyte. TiO2 nanotubes were characterized by SEM and XRD. TiO2 nanotubes on porous Ti were thinner than those on Ti foil. Anatase was formed when TiO2 nanotubes were annealed at 400 °C and fully turned into rutile at 700 °C. To obtain good photodegradation, the optimal heat treatment temperature of TiO2 nanotubes was 450 °C. The porosity of the substrates influenced photodegradation properties. TiO2 nanotubes on porous Ti with 60% porosity had the best photodegradation.

Stomatal Opening Induced by Acetylcholine Is Associated with Cytoskeletal Components

Acetylcholine (Ach) is a key component of animal cholinergic system. Recent experiments demonstrated that Ach, choline acetyltransferase, acetylcholinesterase and Ach receptors are present in all parts of plants and have many functions, including inducing stomatal movement. The authors' previous work has evidenced that microtubules and microfilaments are involved in regulating both stomatal closing and opening. The present investigation is to determine whether stomatal opening induced by Ach is associated with microtubules and microfilaments. The results showed that Ach could induce stomatal opening of Vicia faba L. with or without addition of KCl in the dark. Ach also stimulated protoplast swelling in a K +_free solution in the dark. However, the induction was partially suppressed when the strips and protoplasts were pretreated with either cytochalasin B, an inhibitor of F_actin polymerization, or oryzalin, an inhibitor of plant microtubule polymerization. Thus, our data suggest for the first time that stomatal opening induced by Ach is associated with the dynamics of microtubules and microfilaments.

Preparation of BCEC-Astrocyte Co-culturing Membrane Plate Insert

To prepare a hand-made micropore membrane culture plate insert forco-culture. Methods The plate insert was made using plastic centrifuge tube and micropore membrane.After seeding brain capillary endothelial cells (BCECs) on it (under the effect ofastrocyte-conditioned medium), the plate insert was assessed by analysis of trans-endothelialelectrical resistance (TEER). Results The plate insert has a stability of at least 15 d underculture condition. TEER increased significantly under co-culture condition from (66.1 +- 13.3)Ωcm^2 to (182.2 +- 6.7) Ωcm^2. Conclusion This micropore membrane culture plate insert can beeasily made, on which BCEC culture can be successfully performed. Moreover, it is adjustable andrecyclable. It follows that the plate insert is a useful tool for co-culture and the relatedresearch fields.

Cervical cellulitis and mediastinitis following esophageal perforation:A case report

Chicken bone is one of the most frequent foreign bodies (FB) associated with upper esophageal perforation. Upper digestive tract penetrating FB may lead to life threatening complications and requires prompt management. We present the case of a 52-year-old man who sustained an upper esophageal perforation associated with cervical cellulitis and mediastinitis. Following CT-scan evidence of FB penetrating the esophagus, the impacted FB was successfully extracted under rigid esophagoscopy. Direct suture was required to close the esophageal perforation. Cervical and mediastinal drainage were made immediately. Naso- gastric tube decompression, broad-spectrum intravenous antibiotics, and parenteral hyperalimentation were administered for 10 d postoperatively. An esophagogram at d 10 revealed no leak at the repair site, and oral alimentation was successfully reinstituted. Conclusion: Rigid endoscope management of FB esophageal penetration is a simple, safe and effective procedure. Primary esophageal repair with drainage of all affected compartments are necessary to avoid life-threatening complications.

Controlled synthesis of one-dimensional Au-Ag porous nanostructures

The fabrication of a new type of one-dimensional Au-Ag porous nanotube（NPT） structure was presented based on a facile combination of nanocrystal growth and surface modification.Ag nanowires with various diameters were firstly served as the chemical plating templates via a polyol-process.Then,one-dimensional（1D） Au-Ag porous nanostructures with tailored structural features could be prepared by controlling the individual steps involved in this process,such as nanowire growth,surface modification,thermal diffusion,and dealloying.Structural characterizations reveal these Au-Ag porous nanotubes,non-porous nanotubes and porous nanowires possess novel nano-architectures with multimodal open porosity and excellent structural continuity and integrity,which make them particularly desirable as novel 1D nanocarriers for biomedical,drug delivery and sensing applications.

Aortoduodenal fistula and aortic aneurysm secondary to biliary stent-induced retroperitoneal perforation

Duodenal perforations caused by biliary prostheses are not uncommon, and they are potentially life threatening and require immediate treatment. We describe an unusual case of aortic aneurysm and rupture which occurred after retroperitoneal aortoduodenal fistula formation as a rare complication caused by biliary metallic stent-related duodenal perforation. To our knowledge, this is the first report describing a lethal complication of a bleeding, aortoduodenal fistula and caused by biliary metallic stent-induced perforation.

Delayed presentation of intrathoracic esophageal perforation after pneumatic dilation for achalasia

Pneumatic dilation(PD)is considered to be a safe and effective first line therapy for achalasia.The major adverse event caused by PD is esophageal perforation but an immediate gastrografin test may not always detect a perforation.It has been reported that delayed management of perforation for more than 24 h is associated with high mortality.Surgery is the treatment of choice within 24 h,but the management of delayed perforation remains controversial.Hereby,we report a delayed presentation of intrathoracic esophageal perforation following PD in a 48-year-old woman who suffered from achalasia.She completely recovered after intensive medical care.A review of the literature is also discussed.

A novel method for enhancing the stability of ZSM-5 zeolites used for catalytic cracking of LPG: Catalyst modification by dealumination and subsequent silicon loading

Composite structures of ZSM‐5 zeolites were prepared by the synthesis of mesopores and mi‐cropores using carbon nanotubes as a template. Dealumination of mesopores was performed selec‐tively using trichloroacetic acid, which could only diffuse into the mesopores and not the mi‐cropores owing to the size of the trichloroacetic acid molecules. Empty spaces are created in the catalyst as a result of removal of the Al atoms from the zeolite structure. If Si atoms fill the empty space, then the structure of the mesopores becomes similar to silicates, which do not have any cata‐lytic properties. Silicon containing solution was used to fill the empty spaces, and in doing so, a unique method was developed, by which silicon atoms can directly replace the extracted Al atoms from the mesopore structure. Therefore, by changing the geometry and properties of the mesopores and micropores, the amount of coke reduced from 14%for HZSM‐5 to 3%for the modified zeolite.

Heat Transfer of Boiling R134a and R142b on a Twisted Tube with Machine Processed Porous Surface

The objective of this work was to investigate nucleate pool boiling heat transfer performance and mechanism of R134a and R142b on a twisted tube with machine processed porous surface （T-MPPS tube） as well as to determine its potential application to flooded refrigerant evaporators. In the experimental range, the boiling heat transfer coefficients of R134a on a T-MPPS tube were 1.8-2.0 times larger than those of R134a on a plain tube. In addition, the developed experimental correlations verified that the predictions of the heat transfer coefficients of boiling R134a and R142bon a T-MPPS tube at the experimental conditions were considerably accurate.

Experimental Investigation of a Single-Stage Four-Valve Pulse Tube Refrigerator

In order to simplify the structure of the cold end of the pulse tube refrigerator (PTR) and have a better utilization of the cold energy of the system, a one-stage four-valve pulse tube refrigerator (FVPTR) with an "L" type pulse tube structure and two orifice valves at the hot end of pulse tube has been constructed. Verification experiments show that the two orifice valve structure performs better than one orifice valve structure. A lowest temperature of 67.5 K was obtained at a frequency of 2.5 Hz under a system average pressure of 1.5 MPa with 200 mesh bronze screens as regenerator material, 80 mesh copper screens as stuffing material of heat exchanger. Due to the difficulty in manufacturing the thin "L" type pulse tube, the wall thickness of the pulse tube in the experiment was relatively difficult for us to reach 0.5 mm as that of the ordinary pulse tube, which resulted in relatively big system loss and affected the minimum temperature of the system to some degree.

MEDIASTINAL CAVERNOUS HEMANGIOMA:REPORT OF ONE CASE

MEDIASTINAL cavernous hemangioma is a kind of primary mediastinal mesenchymal tumor that occurs rarely in any age. It was first reported by Shennon in 1914. In this study we reported a case of mediastinal cavernous hemangioma with abnormal vessel originating from left brachiocephalic vein.

Diagnosis and Treatment of Intracranial Cavernous Hemangioma:a Report of 86 Cases

OBJECTIVE To summarize and analyze the clinical manifestations features of imaging diagnosis,and therapeutic efficacy of surgical treatment for intracranial cavernous hemangioma(CH). METHODS Data from 86 cases with intracranial CH from the Department of Neurosurgery of Tianjin Huanhu Hospital,Tianjin, China,during a period from 2000 to 2007,were retrospectively analyzed,and pertinent literature cited. RESULTS Epilepsy,headache,dizziness,sensory disability and limb-kinetic apraxia were the most commonly seen clinical manifestations of the intracranial CH cases.MRI was one of the preferred ways to diagnose CH.All 86 patients were treated with microsurgery,among which neuronavigator-guided surgery was conducted in 16,a second surgical procedure was performed in 3 due to a postoperative intracranial hematoma,and death occurred in 1.All the other 85 patients had a good prognosis. CONCLUSION MRI was the most sensitive diagnostic means for intracranial CH.Microsurgery was the main method to treat intracranial CH.

ESOPHAGUS-STOMACH-ABDOMINAL WALL DRAINAGE FOR DELAYED INTRATHORACIC ESOHPAGEAL PERFORATION

Objective To design a technique of esophagus-stomach-abdominal wall drainage for the de-layed intrathoracic esophageal perforation and to improve the therapeutic results. Methods Four patients were treated by this simplified technique. There were 1 case of lower intrathoracic esophageal perforation to the left thorax , 1 high and 2 middle perforation to the right. This technique used two plastic tubes (chest tube) in a diameter about 1 .2cm . One tube served as an intercostal drainage tube to drain purulent effusion , the other was inserted abdominally through stomach to the esophagus about 10cm above the esophageal perforation. Results The four patients were treated successfully by the esophagus-stomach-abdominal wall drainage. There was no mortality or severe morbidity or complication. Hospitalizations were shortened. Conclusion This technique is simple, safe and effective. It may provide a more promising alternative method of treatment for delayed esophageal perforation, especially in the critically ill patients. The procedure can also be extended to deal with esophagus-stomach anastomotic leak.