Microstructure and mechanical properties of Mg-Gd-Y-Zr alloy cast by metal mould and lost foam casting

The microstructure and mechanical properties of Mg-10.1Gd-3.74Y-0.25Zr （mass fraction, %） alloy （GW104 alloy） cast by metal mould casting （MMC） and lost foam casting （LFC） were evaluated, respectively. It is revealed that different forming modes do not influence the phase composition of as-cast alloy. In the as-cast specimens, the microstructures are similar and composed of α-Mg solid solution, eutectic compound of α-Mg＋Mg 24 （Gd, Y） 5 and cuboid-shaped Mg 5 （Gd, Y） phase; whereas the average grain size of the alloy produced by metal mould casting is smaller than that by lost foam casting. The eutectic compound of the alloy is completely dissolved after solution treatment at 525 ℃for 6 h, while the Mg 5 （Gd, Y） phase still exists after solution treatment. After peak-ageing, the lost foam cast alloy exhibits the maximum ultimate tensile strength of 285 MPa, and metal mould cast specimen 325 MPa at room temperature, while the tensile yield strengths of them are comparable. It can be concluded that GW104 alloy cast by lost foam casting possesses similar microstructure and evidently lower mechanical strength compared with metal mould cast alloy, due to slow solidification rate and proneness to form shrinkage porosities during lost foam casting process.

Influence of casting module on corrosion behavior of Mg-11Gd-3Y alloy

The influences of two kinds of casting modules of metal casting （MC） and expandable pattern casting （EPC） on the corrosion behavior of Mg-11Gd-3Y alloy were studied by electrochemical measurements, scanning electron microscopy （SEM） observation, X-ray diffractometry （XRD） and X-ray photoelectron spectroscopy （XPS） analysis. It is found that the quantity of the Mg 24 （Gd, Y） 5 phase in MC is more than that in EPC due to the cooling rate. There is more alloying element dissolved in the matrix compared with MC. For EPC, the galvanic corrosion effect between the matrix and the Mg 24 （Gd, Y） 5 phase decreases and the corrosion resistance increases compared with the MC. The chief corrosion mode for Mg-11Gd-3Y alloy is pitting corrosion because most of the alloying elements are transformed into intermetallic phases. The average corrosion rate of the MC alloy in the immersion test is five times higher than that of EPC alloy and yttrium is present in the product film, which will provide increased protection for Mg-11Gd-3Y alloy. The electrochemical measurements and immersion test show that the EPC process increases the corrosion resistance compared with the MC Mg-11Gd-3Y alloy.

INVESTIGATION OF FOAM-METAL INTERFACE BEHAVIORS DURING MOLD FILLING OF MAGNESIUM ALLOY LFC PROCESS

The visual observation of the mold filling and the standard analysis-of-variance （ANOVA） for the velocity of the filling metal are conducted to study foam-metal interface behaviors during the mold filling of the lost foam casting （LFC） process of the magnesium alloy. Results show that the foam primarily melts into liquid products instead of gasifying at the pouring temperature of the magnesium alloy. Without the vacuum, the metal fills smoothly with a slightly convex metal front, and the velocity of the filling metal is low and continually decreases as the foam is displaced. The mold filling is governed by the removal of foam decomposition products at the foam-metal interface. However, when the vacuum is applied, the mold filling is controlled by the foam decomposition rate at the foam-metal interface. A pronounced irregular and concave metal front is formed. The velocity of the metal front varies tremendously during the mold filling process and is ruleless. The metal velocity increases rapidly, and the vacuum shows a strong interaction effect with the pouring temperature on the metal velocity. As the vacuum continues to increase, the pouring temperature becomes the most significant factor for the mold filling, while both the vacuum effect and the interaction effect between the vacuum and the pouring temperature on the metal velocity are substantially reduced. Based on experimental results, a model for the foam thermal degradation and the removal of decomposition products occurred at the foam-metal interface is presented during the mold filling of the magnesium alloy LFC process under the vacuum.

Construction and expression of GFP conjugated MIM-I-BAR

To achieve a visible inverse Bin-amphiphysin-Rvs （I-BAR）domain recombinant of missing in metastasis （MIM） protein,the green fluorescent protein （GFP）encoding gene was cloned at the terminal of MIM-I-BAR as a probe.The DNA was successfully constructed on a 6xHis-tagged prokaryotic expression plasmid.The non-GFP labeled MIM-I-BAR encoding plasmid was also constructed as a control. Being successfully transformed into BL21 （DE3 ）cells,the GFP-conjugated MIM-I-BAR （MIM-I-BAR-GFP ） exhibits strong visible fluorescence,and the expression product can be easily detected by visual inspection, a fluorescence microscope, Western blot or ultraviolet and visible spectrophotometer. Moreover, examination of expression efficiency under various culture conditions revealed that the MIM-I-BAR-GFP gene has a high protein yield at 10 ℃,but not at the culture temperature of 37 ℃.This property is much different from that of the non-fluorescent MIM-I-BAR gene. This optimal expression condition is also proved to be feasible for protein production in midi-scale. The fluorescent recombinant MIM-I-BAR-GFP protein can serve as a useful tool in scientific research, biomedical application and pharmaceutical development.

Missing Via Mechanism and Solutions

Missing via has been a defect in semiconductor manufacturing,especially of foundries. Its solution can be rather attractive in yield improvement for relatively mature technology since each percentage point improvement will mean significant profit margin enhancement. However, the root cause for the missing via defect is not easy to determine since many factors,such as, defocus, material re-deposition, and inadequate development,can lead to missing via defects. Therefore, knowing the exact cause for each defect type is the key. In this paper, we will present the analysis methodology used in our company. In the experiments,we have observed three types of missing vias. The first type consists of large areas, usually circular,of missing patterns,which are primarily located near the wafer edge. The second type consists of isolated sites with single partially opened vias or completely unopened vias. The third type consists of relatively small circular areas,within which the entire via pattern is missing. We have first tried the optimization of the developing recipe and found that the first type of missing via can be largely removed through the tuning of the rinse process, which improves the cleaning efficiency of the developing residue. However, this method does not remove missing via of the second and third type. We found that the second type of missing via is related to local defocus caused by topographical distribution. To resolve the third type of missing via defects, we have performed extensive experiments with different types of developer nozzles and different types of photomasks,and the result is that we have not found any distinct dependence of the defect density on either the nozzle or the mask types. Moreover, we have also studied the defect density from three resists with different resolution capability and found a correlation between the defect density and the resist resolution. It seems that,in general, lower resolution resists also have lower defect density. The results will be presented in the paper.

A Low Noise,High Linearity CMOS Receiver for 802.11b WLAN Applications

A 2.4GHz monolithic CMOS receiver with direct-conversion architecture is presented. This quadrature receiver is designed for 802.11b wireless LAN applications at the maximum data rate of 11Mbps as a low-cost solution. Five key blocks,i, e., a low noise amplifier （LNA）, a down-conversion mixer, a variable gain amplifier, a low pass filter, and a DC- offset cancellation circuit,are designed based on system design and low noise high linearity considerations. The necessary auxiliary circuits are also included. Fabricated in SMIC 0.18μm 1p6m RF CMOS process, the receiver＇s performance is measured as：4. 1 dB noise figure, - 7.5dBm input third order intercept point （IIP3） for LNA ＆ mixer at high gain setting, - 14dBm IIP3 for the whole receiver,53dBc @30MHz offset of adjacent channel power rejection,and less than 5mV out- put DC-offset. The receiver consumes 44mA under a 1.8V power supply with I,Q two paths.

Effect of pattern coating thickness on characteristics of lost foam Al-Si-Cu alloy casting

An experimental study on lost foam casting of an Al-Si-Cu alloy was conducted. The main objective was to study the effect of pattern coating thickness on casting imperfection and porosity percentage as well as eutectic silicon spacing of the alloy. The results showed that increasing slurry viscosity and flask dipping time influenced the casting integrity and microstructural characteristics. It was found that thinner pattern coating produced improved mould filling, refined microstructure and higher quality castings containing less porosity.

Evaluation of significant manufacturing parameters in lost foam casting of thin-wall Al-Si-Cu alloy using full factorial design of experiment

Controlling process parameters of lost foam casting （LFC） enables this process to produce defect-free complex shape castings. An experimental investigation on lost foam casting of an A1-Si-Cu cast alloy was carried out. The effects of pouting temperature, slurry viscosity, vibration time and sand size on surface finish, shrinkage porosity and eutectic silicon spacing of thin-wall casting were investigated. A full two-level factorial design of experimental technique was used to identify the significant manufacturing factors affecting the properties of casting. Pouring temperature was found as the most significant factor affecting A1-Si-Cu lost foam casting quality. It was shown that flask vibration time interacted with pouring temperature influenced euteetic silicon spacing and porosity percentage significantly. The results also revealed that the surface quality of the samples cast in fine sand moulds at higher pouring temperatures was almost unchanged, while those cast in coarse sand moulds possessed lower surface qualities. Furthermore, variation in slurry viscosity showed no significant effect on the evaluated properties compared to other parameters.

Vanishing bile duct syndrome in Hodgkin's lymphoma: A case report and literature review

Vanishing bile duct syndrome (VBDS) has been described in different pathologic conditions including infection, ischemia, adverse drug reactions, autoimmune diseases, allograft rejection, and humoral factors associated with malignancy. It is an acquired condition characterized by progressive destruction and loss of the intra-hepatic bile ducts leading to cholestasis. Prognosis is variable and partially dependent upon the etiology of bile duct injury. Irreversible bile duct loss leads to significant ductopenia, biliary cirrhosis, liver failure, and death. If biliary epithelial regeneration occurs, clinical recovery may occur over a period of months to years. VBDS has been described in a number of cases of patients with Hodgkin’s lymphoma (HL) where it is thought to be a paraneoplastic phenomenon. This case describes a 25-year-old man found on liver biopsy to have VBDS. Given poor response to medical treatment, the patient underwent transplant evaluation at that time and was found to have classical stage IIB HL. Early recognition of this underlying cause or association of VBDS, including laboratory screening, and physical exam for lymphadenopathy are paramount to identifying potential underlying VBDS-associated malignancy. Here we review the literature of HL-associated VBDS and report a case of diagnosed HL with biopsy proven VBDS.

EVIDENCE FOR ABRUPT CLIMATIC CHANGES ON NORTHWESTERN MARGIN OF EAST ASIAN MONSOON REGION DURING LAST DEGLACIATION

Based on investigations of the Zhongwei Nanshan aeolian section situated in the southeastern margin of Tengger Desert, carbon-14 and TL (thermoluminescence) dating results and paleoclimatic proxies such as magnetic susceptibility and grain size, we inferred that the northwestern margin of East Asian monsoon region experienced abrupt climatic changes during the last deglaciation. Six oscillation events were identified: Oldest Dryas, Bolling, Older Dryas, Allerod, Intra-Allerod Cold Period (IACP) and Younger Dryas (YD). The summer monsoon was weaker during Oldest Dryas and Younger Dryas when the winter monsoon was stronger. However, during the B/A (Bolling/Allerod) period, the summer monsoon strengthened, reflected by magnetic susceptibility, when the winter monsoon also became strong, which is different from the paleoclimatic pattern established in the East Asian monsoon region. Furthermore, the summer monsoon was nearly in phase with the climate changes inferred from the oxygen isotopic records of Greenland ice cores. It could be speculated that the variations of the sea ice cover in the high latitudes of the North Hemisphere affected the high pressure of Asian continent and the changes of the winter monsoon inland. On the other hand, the sea ice cover variations might have indirectly caused the occurrence of ENSO events that has tightly been related to the summer monsoon in northwest margin of East Asian monsoon region.

Treatment strategies in obstructed defecation and fecal incontinence

Obstructed defecation （OD） and fecal incontinence （FI） are challenging clinical problems, which are commonly encountered in the practice of colorectal surgeons and gastroenterologists. These disorders sodally and psychologically distress patients and greatly impair their quality of life. The underlying anatomical and pathophysiological changes are complex, often incompletely understood and cannot always be determined. As a consequence, many medical, surgical, and behavioral approaches have been described, with no panacea. Over the past decade, advances in an understanding of these disorders together with rational and similar methods of evaluation in anorectal physiology laboratories （ARP）, radiology studies, and new surgical techniques have led to promising results. In this brief review, we discuss treatment strategies and recent updates on clinical and therapeutic aspects of obstructed defecation and fecal incontinence.

Mg alloy surface alloying layer fabricated through evaporative pattern casting technology

The influencing factors of surface alloying layer by evaporative pattern casting technology were investigated.A certain thickness alloying layer was formed on the surface of Mg-alloy matrix when the pouring temperature was 780°C with different vacuum degree and alloying powder size.The surface layer microstructure,micro area composition of the new phase formed on the matrix and the composition characteristics on the surface layer were examined by SEM and element scanning.The results show that the content of aluminum increases greatly on the surface layer.The micro-hardness of alloyed layer has a more obvious increase compared with that of the matrix.The size of alloying element and the vacuum degree are the key factors influencing the alloying layer,with the increase of element powder size from 0.074 to 0.15 mm and vacuum degree from 0.04 to 0.06 MPa,the surface alloying effect becomes better.

A Convergence Theorem for Set-valued Eventual Supermartingle

it In this paper, the properties of set-valued Eventual Supermartingle are discussed. The main result is that suppose {Fn, n ≥ 1） Lfc^1（X） be set-valued Eventual Supermartingle, ifsupE（d（0,Fτ）） 〈 ∞, then Fn →KF and SF^1≠φ, here T is the sets of all T bounded stopping times.

Measurement of the Waveguide Near-field Optical Spot

The characteristic of near-field spots is analyzed.The size of the near field and the heat response time of the hybrid record medium to overcome super paramagnetic effect are calculated based on the heat transfer theory. A novel measuring method for the diameter of near-field recording spot is also presented. Since the grain of the recording media is tiny enough,near-field optical lithography can be accomplished with the aid of atomic force microscope (AFM).The diameter of near-field recording spot can be obtained by specifically designed computer.So the relationship between the near-field recording spot diameter and the probe size of near-field recording system, the near field recording distance coupling between head and disc can be got.

CLINICAL COMPARISON OF THE SELECTIVE SEROTONIN_3 ANTAGONISTS RAMOSETRON AND GRANISETRON IN TREATING ACUTE CHEMOTHERAPY-INDUCED EMESIS,NAUSEA AND ANOREXIA

Feng Fengyi , Zhang Pin , He Youjian 1, Li Yuhong1 , Zhou Meizhen2 , Chen Gang2 and Li Lin2 The Cancer Hospital of the CAMS & PUMC, Beijing 1000211 The Cancer Hospital of Sun Yat Sen University of Medical Sciences, Guangzhou 5100602Beijing Hospital of the Ministry of Health, Beijing 100730

Timedelay based all-frequency correction method for discrete spectrum

Many spectrum correction methods have been developed, but their performance degrades significantly when they are applied to the correction of low frequency component （ LFC ）. It owns to that the model underlying the conventional approaches neglects the interference of the negative frequency in the real signal. A new approach for the correction of the LFC is proposed, which suits all kinds of symmetrical windows. It divides a signal into three sections and makes use of the first spectrum line of each section. Then this approach is modified so that it is also applicable to the correction of the high frequency component. Thus a timedelay-based all-frequency correction method is proposed. The simulation results show that this method is simple and feasible. By this method, the accurate frequency, amplitude and phase of the spectral line can be obtained whether it is close to or far from OHz.

Inactivation of digestive proteases: Another aspect of gut bacteria that should be taken into more consideration

TO THE EDITOR Protein has been one of the main components of our diet, and a large amount of digestive proteases is released into the gut for their digestion. However, these proteases can digest not only the proteins we eat, but also the structural proteins built in our body. To protect against this damage, our body has taken a variety of measures. For instance, these digestive proteases are stored and secreted in the form of zymogen and only activated in gut lumen. These luminal digestive proteases are further prevented from direct contact with epithelial cells by the mucus layer that is incessantly secreted by the goblet cells in gut mucosa. In addition, large quantities of protease inhibitors are produced in the body to inactivate the digestive proteases that have entered the body. Despite these measures, the protection seems still weak and can be easily compromised. For instance,

Design of a New Type of Distribution Valve for Hydraulic Breaker and Analysis of Energy Consumption

Energy consumed by distribution valves causes an energy loss for the output energy of hydraulic breakers, which has a significant influence on its efficiency. A new type of distribution valve used for hydraulic breakers, de- signed to reduce energy consumption, is analyzed on the basis of the operating principle and energy loss of the current distribution valve. The new distribution valve adopts a cone valve and the optimization technique of unequal open de- gree for the valve port. Theoretical calculations and analyses have proven that the new distribution valve can reduce en- ergy loss by 9.0127J, or energy consumption by 31%, during an impact cycle and the efficiency of the hydraulic breaker can be raised by 4.5%. It has the following characteristics: little leakage, little pressure loss and low energy consump- tion.

Prevalence of functional dyspepsia and its subgroups in patients with eating disorders

AIM:To study the prevalence of functional dyspepsia(FD)(Rome Ⅲ criteria) across eating disorders(ED),obese patients,constitutional thinner and healthy volunteers.METHODS:Twenty patients affected by anorexia nervosa,6 affected by bulimia nervosa,10 affected by ED not otherwise specified according to diagnostic and statistical manual of mental disorders,4th edition,nine constitutional thinner subjects and,thirtytwo obese patients were recruited from an outpatients clinic devoted to eating behavior disorders.Twentytwo healthy volunteers matched for age and gender were enrolled as healthy controls.All participants underwent a careful clinical examination.Demographic and anthropometric characteristics were obtained from a structured questionnaires.The presence of FD and,its subgroups,epigastric pain syndrome and postprandial distress syndrome(PDS) were diagnosed according to Rome Ⅲ criteria.The intensity-frequency score of broader dyspeptic symptoms such as early satiety,epigastric fullness,epigastric pain,epigastric burning,epigastric pressure,belching,nausea and vomiting were studied by a standardized questionnaire(0-6).Analysis of variance and post-hoc Sheffè tests were used for comparisons.RESULTS:90% of patients affected by anorexia nervosa,83.3% of patients affected by bulimia nervosa,90% of patients affected by ED not otherwise specified,55.6% of constitutionally thin subjects and 18.2% healthy volunteers met the Postprandial Distress Syndrome Criteria(χ 2,P < 0.001).Only one bulimic patient met the epigastric pain syndrome diagnosis.Postprandial fullness intensity-frequency score was significantly higher in anorexia nervosa,bulimia nervosa and ED not otherwise specified groups compared to the score calculated in the constitutional thinner group(4.15 ± 2.08 vs 1.44 ± 2.35,P = 0.003;5.00 ± 2.45vs 1.44 ± 2.35,P = 0.003;4.10 ± 2.23vs 1.44 ± 2.35,P = 0.002,respectively),the obese group(4.15 ± 2.08vs 0.00 ± 0.00,P < 0.001;5.00 ± 2.45vs 0.00 ± 0.00,P < 0.001;4.10 ± 2.23 vs 0.00 ± 0.00,P < 0.001,respectively) and healthy volunteers(4.15 ± 2.08 vs 0.36 ± 0.79,P < 0.001;5.00 ± 2.45 vs 0.36 ± 0.79,P < 0.001;4.10 ± 2.23 vs 0.36 ± 0.79,P < 0.001,respectively).Early satiety intensity-frequency score was prominent in anorectic patients compared to bulimic patients(3.85 ± 2.23 vs 1.17 ± 1.83,P = 0.015),obese patients(3.85 ± 2.23 vs 0.00 ± 0.00,P < 0.001) and healthy volunteers(3.85 ± 2.23 vs 0.05 ± 0.21,P < 0.001).Nausea and epigastric pressure were increased in bulimic and ED not otherwise specified patients.Specifically,nausea intensity-frequencyscore was significantly higher in bulimia nervosa and ED not otherwise specified patients compared to anorectic patients(3.17 ± 2.56 vs 0.89 ± 1.66,P = 0.04;2.70 ± 2.91 vs 0.89 ± 1.66,P = 0.05,respectively),constitutional thinner subjects(3.17 ± 2.56 vs 0.00 ± 0.00,P = 0.004;2.70 ± 2.91 vs 0.00 ± 0.00,P = 0.005,respectively),obese patients(3.17 ± 2.56 vs 0.00 ± 0.00,P < 0.001;3.17 ± 2.56 vs 0.00 ± 0.00,P < 0.001 respectively) and,healthy volunteers(3.17 ± 2.56 vs 0.17 ± 0.71,P = 0.002;3.17 ± 2.56 vs 0.17 ± 0.71,P = 0.001,respectively).Epigastric pressure intensityfrequency score was significantly higher in bulimic and ED not otherwise specified patients compared to constitutional thin subjects(4.67 ± 2.42 vs 1.22 ± 1.72,P = 0.03;4.20 ± 2.21 vs 1.22 ± 1.72,P = 0.03,respectively),obese patients(4.67 ± 2.42 vs 0.75 ± 1.32,P = 0.001;4.20 ± 2.21vs 0.75 ± 1.32,P < 0.001,respectively) and,healthy volunteers(4.67 ± 2.42 vs 0.67 ± 1.46,P = 0.001;4.20 ± 2.21vs 0.67 ± 1.46,P = 0.001,respectively).Vomiting was referred in 100% of bulimia nervosa patients,in 20% of ED not otherwise specified patients,in 15% of anorexia nervosa patients,in 22% of constitutional thinner subjects,and,in 5.6% healthy volunteers(χ 2,P < 0.001).CONCLUSION:PDS is common in eating disorders.Is it mandatory in outpatient gastroenterological clinics to investigate eating disorders in patients with PDS?

Does recombinant human erythropoietin accelerate correction of post-ulcer-bleeding anaemia?A pilot study

AIM:Anaemia caused by acute upper gastrointestinal bleeding is treated with blood transfusion or iron,but patients usually face a two-month recovery period from post- haemorrhage anaemia.This prospective,randomised,open, pilot study was designed to investigate whether recombinant human erythropoietin(Epoetin)therapy accelerate haematocrit increase in the post-bleeding recovery period. METHODS:We studied hospitalised patients admitted because of acute ulcer bleeding or haemorrhagic gastritis, who had a haematocrit of 27-33% and did not receive blood transfusions.One day after the endoscopic confirmation of cessation of bleeding,they were randomised either to erythropoietin(20 000 IU Epoetin alfa subcutaneously,on days 0,4 and 6)plus iron(100 mg im,on days 1-6,(G_1)or iron only(G_2).Haematocdt was measured on days 0,6,14, 30,45,and 60,respectively. RESULTS:One patient from G_1 and two from G_2 were lost to follow-up.Therefore,14 and 13 patients from G_1 and G_2 respectively were analysed.Demographic characteristics,serum iron,ferritin,total iron binding capacity,reticulocytes,and haernatoait were not significantly different at entry to the study. Median reticulocyte counts were significantly different between groups on day six(G_1:4.0,3.0-6.4 vs G_2:3.5,2.1-4.4%, P=0.03)and median haematocrit on day fourteen [G_1:35.9, 30.7-41.0 vs G_2:32.5,29.5-37.0%(median,range),P=0.04]. CONCLUSION:Erythropoietin administration significantly accelerates correction of anemia after acute ulcer bleeding. The haematocrit gain is equivalent to one unit of transfused blood two weeks after the bleeding episode.