树木死亡与生镜关联的原因分析

现如今全球气候问题越来越严峻,高温、干旱、地震等极端天气频发,相较于森林生态系统自然死亡更新,异常的气候因素导致生态环境的变化对树木的生长发育带来了严重影响,直接或间接导致了树木的死亡。研究环境因子对树木死亡的影响,对掌握森林群落结构、林分更新、森林可持续经营等提供了重要参考。通过样地调查法,调查树木的物种、衰老、分布、死亡、生镜等情况,分析得出树木死亡物种、径级、空间分布、与周围环境条件的关系及规律。

两栖动物面临的威胁及保护对策探讨

两栖动物作为生态系统中重要的类群,20世纪70年代开始在许多地区数量迅速减少,进入90年代,全球范围内两栖动物种群则明显呈衰退趋势。这一现象与人类活动造成环境改变相关。生境破碎化和丧失、农药的使用和重金属离子造成的环境污染、气候变化、工程建设以及其他一些原因对两栖动物造成了影响,针对这些影响因素提出了保护栖息地、减少和控制污染、加强科学研究、减少捕杀、防止外来物种入侵等保护两栖动物的一些建议。

泰山黑革蟹蛛初步观察

黑革蟹蛛是游猎于侧柏树干上的一种蜘蛛,能捕食侧柏树上多种害虫,如侧柏松毛虫,侧柏毒蛾,柏大蚜等。在泰山一年一代。

西藏的羚牛

经过1983——1985年西藏全区自然保护区区划和1987—1991年西藏自治区珍稀野生动物考察。笔者对西藏羚牛的两个亚种的基本情况做了进一步的研究,并参考近年国内外资料,已知西藏羚牛主要分布于西藏东南部的横断山脉伯舒拉岭以西、喜马拉雅山脉东部。采用样方轰赶调查法推算,西藏地区羚牛种群数量为4523±754头。目前,西藏的羚牛受到西藏地区各级政府的重视,并采取了有效的保护措施,但资源浪费和乱捕滥猎仍时有发生。

AFM Observation of GaN Grown on Different Substrates at Low Temperatures

Aim To study the relationship between the substrate temperature and the morphology and properties of GaN. Methods\ Applying the hydride chemical vapor deposition method, GaN films were deposited on different kinds of substrates, including sapphire, Si(111),Si(100),GaAs and GaP(111) both on the P face and the Ga face. The growth was performed at low temperatures of below 700℃. XRD, Hall measurement, cathodoluminescence (CL) and atomic force microscopy (AFM) were used to characterise the film properties. Results\ It was found that the temperature and the nature of substrate materials influence the layer morphology. Conclusion\ The analysis shows that no apparent relationship exists between the optical properties and layer morphology.

Synthesis and Characterization of GaN Nanorods by Ammoniating Ga_2O_3 /Co Films Deposited on Si(111) Substrates

GaN nanorods are successfully synthesized on Si（111） substrates with magnetron sputtering through ammoniating Ga2O3/Co films at 950℃. X-ray diffraction, scanning electron microscopy, high-resolution transmission electron microscopy,and Fourier-transform infrared spectroscopy are used to characterize the samples. The results demonstrate that the nanorods are single-crystal GaN with a hexagonal wurtzite structure and possess relatively smooth surfaces. The growth mechanism of GaN nanorods is also discussed.

Evidence of Ultrastructure and Physiology of F-actin as Component of Plasmodesmata

The characters and ultrastructure of the intercellular connection were revealed in the outer epidermis of the garlic clove sheath by means of fluorescent probe TRITC_Phalloidin (TRITC_Ph) labeling combined with confocal laser scanning microscopy (CLSM), immuno_gold labeling and transmission electron microscopy. These results show that transcellular channel is a complex of rod_like cytoplasm channel and grouped plasmodesmata (PDs) in pit. The former remains a portion of the cell protoplast. The diameter of PD is normally 60-70 nm. The PDs are the real intercellular symplasmic connections of the cells. The transcellular fibers labeled with the TRITC_Ph obviously become narrow in the primary pit fields, which is the same as the characters observed under the electron microscope. The bright fluorescent spot in the primary wall reflects the grouped PDs in pit, and hence the presence of F_actin in the PDs can be confirmed. In immuno_gold labeling experiment, a lot of gold particles were massively distributed in the rod_like cytoplasm channel and grouped PDs. The result provides effective support that these fluorescent filaments possibly are the existing form of F_actin.

In vitro activity of moxifloxacin and piperacillin/sulbactam against pathogens of acute cholangitis

AIM：To analyze the in vitro activity of moxifloxacin and piperacillin/sulbactam against pathogens isolated from patients with acute cholangitis. METHODS： In this prospective study a total of 65 patients with acute cholangitis due to biliary stone obstruction （n = 7）, benign biliary stricture （n = 16）, and malignant biliary stricture （n = 42） were investigated with regard to spectrum of bacterial infection and antibiotic resistance. Pathogens were isolated from bile cultures in all study patients. In 22 febrile patients, blood cultures were also obtained. In vitro activity of moxifloxacin and piperacillin/ sulbactam was determined by agar diffusion. RESULTS： Thirty-one out of 65 patients had positive bile and/or blood cultures. In 31 patients, 63 isolates with 17 different species were identified. The predominant strains were Enterococcus species （26/63）, Ecoli （13/63） and Klebsiella species （8/63）. A comparable in vitro activity of moxifloxacin and piperacillin/sulbactam was observed for E.coli and Klebsiella species. In contrast, Enterococcus species had higher resistances towards moxifloxacin. Overall bacteria showed antibiotic resistances in vitro of 34.9% for piperacillin/sulbactam and 36.5% for moxifioxacin.CONCLUSION： Enterococcus species, E.co/i and Klebsiella species were the most common bacteria isolated from bile and/or blood from patients with acute cholangitis. Overall, a mixed infection with several species was observed, and bacteria showed a comparable in vitro activity for piperacillin/sulbactam and moxifloxacin.

RESEARCH ON MEMBRANE BIOREACTOR TREATING DOMESTIC WASTEWATER AND RELATED MECHANISMS

Experiments on treatment of domestic wastewater by membrane bioreactors were carried out.The results showed that this process could produce good quality effluent with low COD,turbidity and total count of bacteria.With intermittent operation and continuous aeration,the membrane flux was kept steady.The mechanisms of removing COD through membrane,the structure of membrane and filtration resistance were also discussed.

Single Layer Growth of Strained Epitaxy at Low Temperature

Contacting mode atomic force microscopy (AFM) is used to measure the In 0.35 Ga 0.65 As/GaAs epilayer grown at low temperature (460℃).Unlike the normal layer by layer growth (FvdM mode) or self organized islands growth (SK mode),samples grown under 460℃ are found to be large islands with atomic thick terraces.AFM measurements reveale near one monolayer high steps.This kind of growth is good between FvdM and SK growth modes and can be used to understand the evolution of strained epitaxy from FvdM to SK mode.

Pedunculated Brunner's gland hamartoma of the duodenum causing upper gastrointestinal hemorrhage

A case of pedunculated Brunner＇s gland hamartoma （BGH） of the duodenum causing upper gastrointestinal （GI） hemorrhage is reported. The patient was a 47-year-old man who visited our hospital for further evaluation of tarry stools and shortness of breath. Endoscopic examination of the upper digestive tract revealed a large peduncular polyp with bleeding, about 30 mm in diameter, arising from the wall of the second portion of the duodenum. GI bleeding occurred from the base of the stalk of the polyp. Endoscopic polypectomy was performed. Histological examination of the specimen revealed that the main body of the polyp contained several Iobules of mature Brunner＇s gland with areas of cystic dilatation. The surface epithelium consisted of normal duodenal mucosa with areas of focal ulceration. This polyp was diagnosed as a BGH. The symptom of tarry stools resolved after endoscopic resection. Our case shows that treatment is necessary for duodenal BGH if GI bleeding occurs.

Extrathyroidal Implantation of Thyroid Hyperplastic/neoplastic Cells after Endoscopic Thyroid Surgery

Objective To report a case of the implantation of thyroid hyperplastic or neoplastic tissue after endoscopic thyroidectomy and discuss this complication in aspects of prevalence, pathogenesis, protection, and therapies. Methods A systematic search of literature from the PubMed database was conducted for identifying eligible studies on implantation of thyroid hyperplastic or neoplastic cells after endoscopic thyroid surgery. Results Overall, 5 reported cases on patients suffering from endoscopic thyroid surgery with implantation of thyroid hyperplastic or neoplastic cells were included in the systematic review. Conclusions Unskilled surgeons, rough intraoperative surgical treatment, scarification or rupture of tumor, contamination of instruments, chimney effect, aerosolization of tumor cells may be associated with the implantation after endoscopic thyroidectomy. To minimize the risk of such complication, we should be more meticulous and strict the endoscopic surgery indications.

Endoscopic naso-pancreatic drainage for the treatment of pancreatic fistula occurring after LDLT

Pancreatic fistula is a quite rare complication in patients who undergo living donor liver transplantation(LDLT).However,in the cases that show pancreatic fistula,the limited volume of the graft and the resultant inadequate liver function may complicate the management of the fistula.As a result,the pancreatic fistula may result in the death of the patient.We present 2 cases in whichendoscopic treatment was effective against pancreatic fistulas that developed after LDLT.In case 1,a 61-yearold woman underwent LDLT for primary biliary cirrhosis.Because of a portal venous thrombus caused by a splenorenal shunt,the patient underwent portal vein reconstruction,and a splenorenal shunt was ligated on postoperative day(POD)7.The main pancreatic duct was injured during the manipulation to achieve hemostasis,thereby necessitating open drainage.However,discharge of pancreatic fluid continued even after POD 300.Endoscopic naso-pancreatic drainage(ENPD)was performed,and this procedure resulted in a remarkable decrease in drain output.The refractory pancreatic fistula healed on day 40 after ENPD.In case 2,a 58-year-old man underwent LDLT for cirrhosis caused by the hepatitis C virus.When the portal vein was exposed during thrombectomy,the pancreatic head was injured,which led to the formation of a pancreatic fistula.Conservative therapy was ineffective;therefore,ENPD was performed.The pancreatic fistula healed on day 38 after ENPD.The findings in these 2 cases show that endoscopic drainage of the main pancreatic duct is a less invasive and effective treatment for pancreatic fistulas that develop after LDLT.

Patient and physician perception of natural orifice transluminal endoscopic appendectomy

AIM:To investigate perception of natural orifice transluminal endoscopic surgery(NOTES)as a potential technique for appendectomy.METHODS:One hundred patients undergoing endoscopy and 100 physicians were given a questionnaire describing in detail the techniques of NOTES and laparoscopic appendectomy.They were asked about the reasons for their preference,choice of orifice,and extent of complication risk they were willing to accept.RESULTS:Fifty patients(50%)and only 21 physicians(21%)preferred NOTES(P<0.001).Patients had previously heard of NOTES less frequently(7%vs73%,P<0.001)and had undergone endoscopy more frequently(88%vs 36%,P<0.001)than physicians.Absence of hernia was the most common reason for NOTES preference in physicians(80%vs 44%,P= 0.003),whereas reduced pain was the most common reason in patients(66%vs 52%).Physicians were more likely to refuse NOTES as a novel and unsure technique(P<0.001)and having an increased risk of infection(P<0.001).The preferred access site in both groups was colon followed by stomach,with vagina being rarely preferred.In multivariable modeling,those with high-school education[odds ratio(OR):2.68,95% confidence interval(CI):1.23-5.83]and prior colonoscopy(OR:2.10,95%CI:1.05-4.19)were more likely to prefer NOTES over laparoscopic appendectomy.There was a steep decline in NOTES preference with increased rate of procedural complications.Male patients were more likely to consent to their wives vaginal NOTES appendectomy than male physicians(P=0.02).CONCLUSION:The preference of NOTES for appendectomy was greater in patients than physicians and was related to reduced pain and absence of hernia rather than lack of scarring.

Appendiceal mass:Is interval appendicectomy “something of the past” ?

The need for interval appendicectomy (I.A) after successful conservative management of appendiceal mass has recently been questioned.Furthermore,emergency appendicectomy for appendiceal mass is increasingly performed with equal success and safety to that performed in non-mass forming acute appendicitis.There is an increasing volume of evidence-although mostly retrospective-that if traditional conservative management is adopted,there is no need for routine I.A except for a small number of patients who continue to develop recurrent symptoms.On the other hand,the routine adoption of emergency laparoscopic appendicectomy (LA) in patients presenting with appendiceal mass obviates the need for a second admission and an operation for I.A with a considerable complication rate.It also abolishes misdiagnoses and deals promptly with any unexpected ileo-cecal pathology.Moreover,it may prove to be more cost-effective than conservative treatment even without I.A due to a much shorter hospital stay and a shorter period of intravenous antibiotic administration.If emergency LA is to become the standard of care for appendiceal mass,I.A will certainly become 'something' of the past.

Non-parasitic splenic cysts: A report of three cases

Primary splenic cyst is a relatively rare disease, and the majority of cases are classified as epithelial cysts. Three cases with nonparasitic splenic cysts are presented: two epithelial and one pseudocyst. All cases had an atypical symptomatology, consisted mainly of fullness in the left upper abdomen and a palpable mass. Preoperative diagnosis was established with ultrasonography and computerized tomography. Two cases with large cysts located in the splenic hilum were treated with open complete splenectomy. The most recent case, a pseudocyst, was managed laparoscopically with partial cystectomy. All cases did not have any problems or recurrence during follow-up. Laparoscopic partial cystectomy is an acceptable procedure for the treatment of splenic cysts, because it cures the disease preserving the splenic tissue. Complete splenectomy is reserved for cases in which cyst excision cannot be done otherwise.

Biomechanical change of lumbar unilateral graded facetectomy and strategies of its microsurgical reconstruction:report of 23 cases

Objective： To evaluate the lumbar stability and the primary clinical results of unilateral facetectomy, transforaminal lumbar interbody fusion （TLIF） and unilateral pedicle screw fixation by X-Tube system. Methods： Five human lumbar cadaveric functional spine units（FSU） were obtained and graded facetectomy by 0, 1/4, 1/2, 3/4 and 4/4 were performed respectively on the left articular process of them. The stability of these 5 models was evaluated at flexion, extension, lateral bending and axial rotation. After a serial of biomechanical researches, 23 patients from June 2004 to March 2006 in our department underwent unilateral facetectomy, transforaminal lumbar interbody fusion （posterior lumbar interbody fusion） and unilateral pedicle screw instrumentation by X-Tube system. After general anaesthesia, with the guide of fluoroscopy and using X-Tube system, procedures of unilateral endoscopic facetectomy, spinal nerve root decompression, autologus spongy bone transplantation, one cage oblique insertion and unilateral pedicle screw instrumentation were performed. Results： There was no significant difference in flexion, extension, lateral bending and axial rotation of lumbar motion range after unilateral graded facetectomy. The stability of left/right axial direction was greatly affected when the range of graded facetectomy exceed 1/2. According to the Nakai criteria, for the 23 patients, the clinical result was excellent in 15 （65.2%）, good in 6 （26.1%） and fair in 2 （8.7%）. The fusion rate was 95.6% in excellent and good cases. Although partial absorption of bone grafts was observed in 1 case which might indicate a unsuccessful fusion, there was no loosing and replacement of instrument and no clinical symptoms occurred. Conclusion： The lumbar stability will be affected significantly when the range of graded facetectomy exceeds 1/2. Procedures of unilateral facetectomy, transforaminal lumbar interbody fusion and unilateral pedicle screw fixation is an optional strategy for microsurgical reconstruction, though the indications of the procedure should be carefully restricted.

Differences in characteristics of colorectal neoplasm between young and elderly Thais

AIM: To analyze the differences of clinical characteristics of colorectal neoplasm including polyps between the elderly and young Thai patients.METHODS: Colonoscopy database from December 2000 to October 2004 was retrospectively analyzed. There were 1822 eligible patients who underwent colonoscopy (with a mean age of 56.6 years). Patients were classified into two groups: the older age group (aged ≥ 60 years; n = 989) and the younger age group (aged < 60 years; n = 833). Data were recorded on age, colonoscopic indications, tumor location, colonoscopic findings and their related histological findings. RESULTS: Colorectal malignancy related lesions were more often found in the older age group (21%) than in the younger age group (12%). Left-sided lesions were detected more commonly than right-sided in both age groups in approximately two-thirds of all cases. Hematochezia showed greater association with left-sided lesions in the elderly. No relationship was found between age and neoplasm staging and severity.CONCLUSION: The chance of detecting colorectal neoplasm by colonoscopy was higher in the elderly than in the young Thais. However, both groups had the lesions predominantly located in the left side.

Obsevation for Epidermal Ultrastructure of Nostoc sphaeroides Kutzing under Scanning Electron Microscope

[Objective]The experiment aimed to explore a new way for observing surface structure of Nostoc sphaeroides Kutzing. [Method] The scanning electron microscope was used to observe the epidermal ultrastructure of wild and cultured Nostoc sphaeroides Kutzing. [ Result] The epidermis of wild and cultured Nostoc sphaeroides Kutzing showed mixture structure of fibril colloid which was reticular arranged. The difference between wild and cultured Nostoc sphaeroides Kutzing was that the outer epidermis of cultured Nostoc sphaeroides Kutzing had trichome distribution but the wild Nostoc sphaeroides Kutzing did not has such distribution. The obsevation results of under smaller than 10 μm by scanning electron microscope was touched thick and showed many folds and distortions. [ Conclusion] The scanning electron microscope was an effective way to study development of Nostoc sphaeroides Kutzing colony and it was worth popularizing.

Usefulness of biodegradable stents constructed of poly-l-lactic acid monofilaments in patients with benign esophageal stenosis

AIM： To report 13 patients with benign esophagea stenosis treated with the biodegradable stent. METHODS： We developed a Ultraflex-type stent by knitting poly-/-lactic acid rnonofilaments. RESULTS： Two cases were esophageal stenosis caused by drinking of caustic liquid, 4 cases were due to surgical resection of esophageal cancers, and 7 cases were patients with esophageal cancer who received the preventive placement of biodegradable stents for postendoscopic mucosal dissection （ESD） stenosis. The preventive placement was performed within 2 to 3 d after ESD. In 10 of the 13 cases, spontaneous migration of the stents occurred between 10 to 21 d after placement. In these cases, the migrated stents were excreted with the feces, and no obstructive complications were experienced. In 3 cases, the stents remained at the proper location on d 21 after placement. No symptoms of re-stenosis were observed within the follow-up period of 7 mo to 2 years. Further treatment with balloon dilatation or replacement of the biodegradable stent was not required. CONCLUSION： Biodegradable stents were useful for the treatment of benign esophageal stenosis, particularly for the prevention of post-ESD stenosis.