Effect of phosphorus and heat treatment on microstructure of Al-25%Si alloy

It is known that phosphorus can refine the primary silicon and heat treatment can spheroidize the eutectic silicon. This paper presents an optimal combination of heat treatment processes and P refinement on hypereutectic AI-Si alloy. The optimal P addition amount, and the solution and aging temperatures for AI-25%Si alloy were obtained through the orthogonal experiment, and their modification effects were discussed. The results show that P addition has the greatest modification effect, followed by aging temperature, and the modification effect of solution temperature is the least. The optimized modification parameters are： addition of 0.6% P, solution at 540℃ and aging at 160℃. In addition, the cooling curve, superheating and hardness of the alloy were also analyzed.

Evaluation of modified hemodilution combined therapy in the treatment of acute ischemic stroke in the elderly

BACKGROUND： Thrombolysis therapy is not suitable for the elderly patients with acute ischemic stroke who delayed to be diagnosed for more than 3 hours, but traditional medicine is also not very ideal. OBJECTIVE： To observe the clinical therapeutic effect of modified hemodilution combined therapy applied in elderly patients with acute cerebral thrombosis and analyze the mechanism of this therapeutic method. DESIGN： 1：1 paired grouping according to gender and controlled observation SETTING： Department of Internal Medicine, Chengzhanyuan District, First Hospital Affiliated to Zhejiang University. PARTICIPANTS： Totally 90 elderly patients with acute ischemic stroke who received the treatment in the Cadre Ward and Mental Ward, Department of Internal Medicine, Chengzhanyuan District, First Hospital Affiliated to Zhejiang University from March 1996 to June 2004 were recruited. They all met the diagnosis criteria revised by the Fourth Academic Conference of National Cerebrovascular Diseases in 1995 and were diagnosed as acute ischemic stroke by skull CT. They were informed of therapeutic plan and detected items. According to 1：1 paired principle in gender, 90 enrolled patients were assigned into treated group （n=45） and control group （n=45）. There were 39 male and 6 female in the treatment group, and they were aged （76±6）years, ranging from 71 to 84 years, and hospitalized at the 14^th to 76^th hours after onset. There were 39 male and 6 female in the control group, and they were aged （76±6）years , ranging from 70 to 82 years, and hospitalized at the 16^th to 72^th hours after onset. METHODS： Therapeutic method： Patients of treated group received modified hemodilution combined therapy. 200 mL whole blood of patients was exchanged with 500 mL dextran-40 （including 20 mL danshen parenteral solution and 32 mg heparin） at the beginning of therapy; From the 2^nd day, compound huangqi tea bag （Huangqi mainly, including danshen, honghua, chuanxiong, shishao and a little acetyl salicylic acid） was made, twice a day, 1 bag once. At the same time, the above-mentioned dextran-40 liquid of 500 mL was intravenously injected, once a day, 14 days in total; On the 6^th day after therapy, the above-mentioned aseptic autoblood stored in refrigerator at 4℃ was transfused back into the patients following pre-treatment of high-concentration oxygenation and ultraviolet irradiation by light quantum instrument. Patients of control group were intravenously injected of 0.4 g venoruton（Traditional Chinese medicine compound parenteral solution for promoting blood circulation and removing blood stasis ） and 50 g/L glucose of 500 mL, 75 mg acetosal was taken orally, once a day, 14 days in total. ② Measurement and observation of index： Blood coagulation index, change of platelet aggregation rate and change of hemorrheology of patients in two groups were monitored before and after therapy. The level of blood lipid of patients in two groups was measured with American Beckman automatic biochemistry analyzer. Blood flow rate of middle cerebral artery of resting electrocardiogram were measured with American HP SONOS 2500 sonoscope. Neuro-dysfunction score revised in the national conference （1995） was used to evaluate the recovery of neurological function of the patients in two groups at the 3rd, 5^th, 7^th and 14^th days after therapy. ③Therapeutic effect and adverse effect were observed at the same time. MAIN OUTCOME MEASURES ： ① Changes of coagulation index, blood lipid level and hemorheology; ② Blood flow rate of middle cerebral artery and NDS of patients with acute ischemic stroke in two groups; ③Adverse effect of drug. RESULTS： Totally 90 patients were enrolled in the experiment. One patient from treated group died of hyperosmolar nonketotic diabetic coma of complicated diabetes mellitus. One patient from control group died of severe pulmonary infection. The rest 88 patients entered the stage of result analysis. ① Change of coagulation index and platelet aggregation rate： prothrombin time （PT）, activated partial thromboplastin time （APTT） and thrombin time （TT） of patients after therapy were significantly longer than those before therapy in the treated group and those after therapy in control group [After therapy in treated group： （18.4±1.9）, （41.8±2.1）, （19.7±1.7） s, Before therapy in treated group： （13.4±1.3）, （35.8±1.3）, （12.5±0.9） s, After therapy in control group： （16.9±1.5）, （39.1±1.1）, （11.9±2.1） s, P〈 0.05]：Concentration of fibrinogen （Fbg） after therapy was significantly lower than that before therapy in the treated group and that after therapy in control group[After therapy in treated group： （3.4±0.4） g/L; Before therapy in treated group： （4.3±0.7） g/L; After therapy in control group：（4.0±0.6） g/L; P 〈 0.05]. Platelet aggregation rate decreased from （37.92 ±0.85）% before therapy to （26.42±1.01）% after therapy （P 〈 0.01）. ②Change of blood lipid level： Levels of total cholesterol （TC）, triacylglycerol（TG） and low density lipoprotein cholesterol （LDL-C） of patients after therapy were significantly lower than those before therapy in treated group and those after therapy in control group [After therapy in treated group： （5.2±0.9）, （1.9±0.9）, （2.08±1.1） mmol/L, before therapy in treated group： （5.9±1.2）, （2.8±0.9）, （3.94±0.5） mmol/L, After therapy in control group： （6.0±1.1）, （2.6±0.8）, （3.84±0.9） mmol/L, P 〈 0.05]. ③Change of hemorheology index： Hematocrit of patients of treated group was significantly lower after therapy than before therapy [Before therapy： （43.84±4.55）% ;After therapy： （40.48±4.02）%;P 〈 0.05]. Blood flow rate of middle cerebral artery of patients of treated group was significantly lower before therapy than after therapy [（90±1.2）, （97±2.1） cm/s,P〈 0.01]. ⑤NDS of patients in treated group was significantly lower than of control group 14 days after therapy. The total effective rate after therapy was significantly higher in the treated group than in the control group （93%,78%, P 〈 0.05）. ⑥There was no obvious adverse effect. CONCLUSION： Modified hemodilution combined therapy can improve hemorheology, decrease hematocrit, increase blood flow rate of middle cerebral artery, so as to improve the impaired clinical neurological function of elderly patients with acute cerebral thrombosis through anticoagulation and antiplatelet aggregative activity as well as regulating blood lipid.

Comparisons of Three Recurrent Selection Methods in the Improvement of Maize Populations

The maize population Csyn 4 was improved for three cycles with three recurrent selection methods MS1, MS1-HS, and MHSRRS in northern China. A total of 40 NC Ⅱ testcrosses were made by four testers with Csyn 4 and 10 improved populations, which were evaluated in four environments in the cropping season of 2005. Analysis of variance indicated a significant progress （P〈 0.05） in yield and other chief agronomic traits in the improved populations and testcrosses, demonstrating that the three recurrent selection methods were effective for increasing grain yield of testcrosses and improvement of general combining ability in maize population. The average grain yield increase of population Csyn 4 in MS1, MS1-HS, and MHSRRS recurrent selections was 266.7 kg ha^-1 （5.3%）, 288.0 kg ha^-1 （5.7%）, and 231.3 kg ha^-1 （4.6%） per cycle, while the grain yield of S 1 progeny of population for Csyn 4 was increased by 420.0 kg ha^-1 （10.9%）, 376.0 kg ha^-1 （9.8%）, and 414.7 kg ha^-1 （10.8%） per cycle in MS1, MS1-HS, and MHSRRS recurrent selections, respectively. Linear responses （b） in the MS1, MS1-HS, and MHSRRS recurrent selections were the same as the realized responses of the selection （G） for grain yield increase of Csyn 4 and S1 progeny of the populations. The grain yield of testcrosses increased by 3.3-5.2% on average per cycle. The value of heterosis did not display any differences amongst the different cycles of selections. The GCA for yield component traits of population Csyn 4 was improved significantly by means of three selection methods, whereas the GCA for plant height, ear height, days to silking, and days to pollen did not show significant increase in the recurrent selections. GCA for the number of tassel branches were decreased in the selections, while GCA for the number of plant leaves were increased, but the difference was not significant.

Modified fixation for periprosthetic supracondylar femur fractures:Two case reports and review of the literature

BACKGROUND Periprosthetic supracondylar femoral fractures(PSFs)present a challenge in terms of optimizing fixation in patients with poor bone quality.Surgical treatment and peri-operative management of PSFs in the elderly remain a burden for orthopedic surgeons.Among different treatment options,locking plate(LP)and retrograde intramedullary nail(RIMN)have shown favorable results.However,reduced mobility and protected weight-bearing are often present in the postoperative older population.With a purpose of allowing for early weight-bearing,a modified nail plate combination(NPC)was redesigned for PSF management.CASE SUMMARY In our cases,two elderly osteoporotic female underwent total knee arthroplasty(TKA),and then suffered from low energy trauma onto their knees after falling to the floor.Plain radiographs or computed tomography scans demonstrated oblique or transverse PSFs,both of which occurred at the distal femur above TKA.The modified NPC technique was performed for treatment of PSFs.The patient was made foot flat weight bearing in 1 wk.At 6-mo follow-up,the union was ultimately achieved using modified NPC with satisfactory implant outcomes.CONCLUSION Neither LP nor RIMN alone may provide adequate support to allow for union in circumstances where the patient has severely osteopenic bone.Therefore,developing a modified implant offer an alternative choice for treating PSFs.These two cases revealed that this technique is a viable option for the geriatric osteoporotic PSFs,offering safe,early weight bearing and favorable clinical outcomes.

Effects of soil metal(loid)s pollution on microbial activities and environmental risks in an abandoned chemical smelting site

Abandoned chemical smelting sites containing toxic substances can seriously threaten and pose a risk to the surrounding ecological environment.Soil samples were collected from different depths(0 to 13 m)and analyzed for metal(loid)s content and fractionation,as well as microbial activities.The potential ecological risk indices for the different soil depths(ordered from high to low)were:1 m(D-1)>surface(S-0)>5 m(D-5)>13 m(D-13)>9 m(D-9),ranging between 1840.65-13,089.62,and representing extremely high environmental risks,of which Cd(and probably not arsenic)contributed to the highest environmental risk.A modified combined pollution risk index(MCR)combining total content and mobile proportion of metal(loid)s,and relative toxicities,was used to evaluate the degree of contamination and potential environmental risks.For the near-surface samples(S-0 and D-1 layers),the MCR considered that As,Cd,Pb,Sb,and Zn achieved high and alarming degrees of contamination,whereas Fe,Mn,and Ti were negligible or low to moderate pollution degrees.Combined microcalorimetry and enzymatic activity measurements of contaminated soil samples were used to assess the microbial metabolic activity characteristics.Correlation analysis elucidated the relationship between metal(loid)s exchangeable fraction or content and microbial activity characteristics(p<0.05).The microbial metabolic activity in the D-1 layer was low presumably due to heavy metal stress.Enzyme activity indicators and microcalorimetric growth rate(k)measurements were considered sensitive indicators to reflect the soil microbial activities in abandoned chemical smelting sites.