Objective Io evaluate changes in morphology of the cesarean scar and uterus between one and two years after cesarean section using high-resolution,three dimensional T2-weighted sampling perfection with application opt...Objective Io evaluate changes in morphology of the cesarean scar and uterus between one and two years after cesarean section using high-resolution,three dimensional T2-weighted sampling perfection with application optimized contrast using diflerent flip angle evolutions Magnetic Resonance Imaging(3DT2w SPACE MRI).Methods This prospective study was performed to investigate morphological changes in the cesarean scars and uterus from one to two years after cesarean section using high-resolution,3D T2w SPACE MRI.The healthy volunteers having no childbearing history were recruited as the controls.All data were measured by two experienced radiologists.All data with normal distribution between the one-year and two-year groups were compared using a paired-sample t test or independent t test.Results Finally,46 women took a pelvic MR examination one year after cesarean section,and a subset of 15 completed the same examination again after two years of cesarean section.Both the uterine length and the anterior wall thickness after two years of cesarean section(5.75±0.46 and 1.45±0.35 cm)were significantly greater than those measured at one year(5.33±0.59 and 1.25±0.27 cm)(t=-2.363 and-2.175,P=0.033 and 0.048).No significant difference was shown in myometrial thickness two years after cesarean section(1.45±0.35 cm)with respect to the control group(1.58±0.21 cm,P=0.170).Nine women who underwent MRI twice were considered to have scar diverticula one year after cesarean section,and still had diverticula two years after cesarean section.The thickness,height,and width of the uterine scar showed no significant change from one to two years(all P>0.05).Conclusions 3D T2w SPACE MRI provides overall morphologic details and shows dynamic changes in the scar and the uterus between one and two years after cesarean section.Scar morphology after cesarean section reached relatively stable one year after cesarean section,and uterine morphology was closer to normal two years after cesarean section.展开更多
Discoveries in Charles Darwin’s laboratory led to modern herbicides. Darwin discovered the internal mechanism that directed plants to grow toward sunlight and sources of water. Scientists in Europe and America later ...Discoveries in Charles Darwin’s laboratory led to modern herbicides. Darwin discovered the internal mechanism that directed plants to grow toward sunlight and sources of water. Scientists in Europe and America later called this mechanism a plant’s hormone response system. Administrators and scientists, including Dr. Ezra J. Kraus, the Head of the Botany Department at the University of Chicago and a plant physiologist, suggested on the eve of WWII that weed killers had significant military value as chemical weapons. Dr. Kraus obtained access to a synthetic chemical, 2,4-D, and found that when the chemical was absorbed through the leaves of plants, it destroyed a plant’s hormones. After exposure, the plant experienced rapid and uncontrolled growth, and then the leaves shriveled, died and fell off. Dr. Kraus obtained funding for his Department of Botany research program from Department of Defense (DOD) during World War II (WWII). Camp Detrick (Biological Weapons Laboratory) scientists later obtained samples of newly created 2,4,5-T which contained unknown amounts of the by-product dioxin TCDD. In the 1950s and 1960s, Fort Detrick military scientists formulated the herbicide Agent Orange, which was a 50 - 50 mixture of 2,4-D and 2,4,5-T. These dual purpose herbicides were used by DOD and USDA. American and European farmers in the 1940s used 2,4-D and 2,4,5-T to eliminate weeds from pastureland and cropland. After WWII, synthetic herbicides (and pesticides) development continued in tandem with production of synthetic fertilizers and breeding of high-yield plant varieties. These new agricultural products were then shipped worldwide to increase crop yields, as part of the Green Revolution. This new system of agricultural technologies was intended to eliminate global starvation and increase food security by increasing field and farm crop yields. In contrast, the goal of military use of herbicides, as chemical weapons, was to defoliate jungle forests and destroy food crops as a strategy to win battles and wars. The primary objective of this research study is to describe how agricultural herbicides became tactical chemical weapons. A current assessment will address the environmental impacts of military and environmental chemical weapons on the United States and Vietnam ecosystems and need for additional dioxin TCDD hotspot clean-up efforts.展开更多
Let D be an integral domain, ψ（D） （resp., t-ψ（D）） be the set of all valuation （resp., t-valuation） ideals of D, and w-P（D） be the set of primary w-ideals of D. Let D[X] be the polynomial ring over 19, c（f...Let D be an integral domain, ψ（D） （resp., t-ψ（D）） be the set of all valuation （resp., t-valuation） ideals of D, and w-P（D） be the set of primary w-ideals of D. Let D[X] be the polynomial ring over 19, c（f） be the ideal of D generated by the coefficients of f ∈ D[X], and Nv = {f∈ D[X] ｜ c（f）v = D}. In this paper, we study integral domains D in which w-P（D） t-ψ（D）, t-ψ（D） w-P（D）, or t-ψ（D） = w-P（D）. We also study the relationship between t-ψ（D） and ψ（D[X]Nv）, and characterize when t-ψ（A ＋ XB[X]） w-P（A ＋ XB[X]） holds for a proper extension A c B of integral domains.展开更多
文摘Objective Io evaluate changes in morphology of the cesarean scar and uterus between one and two years after cesarean section using high-resolution,three dimensional T2-weighted sampling perfection with application optimized contrast using diflerent flip angle evolutions Magnetic Resonance Imaging(3DT2w SPACE MRI).Methods This prospective study was performed to investigate morphological changes in the cesarean scars and uterus from one to two years after cesarean section using high-resolution,3D T2w SPACE MRI.The healthy volunteers having no childbearing history were recruited as the controls.All data were measured by two experienced radiologists.All data with normal distribution between the one-year and two-year groups were compared using a paired-sample t test or independent t test.Results Finally,46 women took a pelvic MR examination one year after cesarean section,and a subset of 15 completed the same examination again after two years of cesarean section.Both the uterine length and the anterior wall thickness after two years of cesarean section(5.75±0.46 and 1.45±0.35 cm)were significantly greater than those measured at one year(5.33±0.59 and 1.25±0.27 cm)(t=-2.363 and-2.175,P=0.033 and 0.048).No significant difference was shown in myometrial thickness two years after cesarean section(1.45±0.35 cm)with respect to the control group(1.58±0.21 cm,P=0.170).Nine women who underwent MRI twice were considered to have scar diverticula one year after cesarean section,and still had diverticula two years after cesarean section.The thickness,height,and width of the uterine scar showed no significant change from one to two years(all P>0.05).Conclusions 3D T2w SPACE MRI provides overall morphologic details and shows dynamic changes in the scar and the uterus between one and two years after cesarean section.Scar morphology after cesarean section reached relatively stable one year after cesarean section,and uterine morphology was closer to normal two years after cesarean section.
文摘Discoveries in Charles Darwin’s laboratory led to modern herbicides. Darwin discovered the internal mechanism that directed plants to grow toward sunlight and sources of water. Scientists in Europe and America later called this mechanism a plant’s hormone response system. Administrators and scientists, including Dr. Ezra J. Kraus, the Head of the Botany Department at the University of Chicago and a plant physiologist, suggested on the eve of WWII that weed killers had significant military value as chemical weapons. Dr. Kraus obtained access to a synthetic chemical, 2,4-D, and found that when the chemical was absorbed through the leaves of plants, it destroyed a plant’s hormones. After exposure, the plant experienced rapid and uncontrolled growth, and then the leaves shriveled, died and fell off. Dr. Kraus obtained funding for his Department of Botany research program from Department of Defense (DOD) during World War II (WWII). Camp Detrick (Biological Weapons Laboratory) scientists later obtained samples of newly created 2,4,5-T which contained unknown amounts of the by-product dioxin TCDD. In the 1950s and 1960s, Fort Detrick military scientists formulated the herbicide Agent Orange, which was a 50 - 50 mixture of 2,4-D and 2,4,5-T. These dual purpose herbicides were used by DOD and USDA. American and European farmers in the 1940s used 2,4-D and 2,4,5-T to eliminate weeds from pastureland and cropland. After WWII, synthetic herbicides (and pesticides) development continued in tandem with production of synthetic fertilizers and breeding of high-yield plant varieties. These new agricultural products were then shipped worldwide to increase crop yields, as part of the Green Revolution. This new system of agricultural technologies was intended to eliminate global starvation and increase food security by increasing field and farm crop yields. In contrast, the goal of military use of herbicides, as chemical weapons, was to defoliate jungle forests and destroy food crops as a strategy to win battles and wars. The primary objective of this research study is to describe how agricultural herbicides became tactical chemical weapons. A current assessment will address the environmental impacts of military and environmental chemical weapons on the United States and Vietnam ecosystems and need for additional dioxin TCDD hotspot clean-up efforts.
文摘Let D be an integral domain, ψ（D） （resp., t-ψ（D）） be the set of all valuation （resp., t-valuation） ideals of D, and w-P（D） be the set of primary w-ideals of D. Let D[X] be the polynomial ring over 19, c（f） be the ideal of D generated by the coefficients of f ∈ D[X], and Nv = {f∈ D[X] ｜ c（f）v = D}. In this paper, we study integral domains D in which w-P（D） t-ψ（D）, t-ψ（D） w-P（D）, or t-ψ（D） = w-P（D）. We also study the relationship between t-ψ（D） and ψ（D[X]Nv）, and characterize when t-ψ（A ＋ XB[X]） w-P（A ＋ XB[X]） holds for a proper extension A c B of integral domains.
文摘将经过多级破碎分选所得的废线路板粉末过60目筛,以2 mol/L HCl溶液、超纯水洗涤,并用丙酮脱水。将预处理后的滤渣、滤纸填入萃取池,或者用新滤纸包裹后置于索氏提取管内,添加5μL内标物,分别用加速溶剂萃取法(ASE)或索氏提取(SE)法进行萃取,依次采用多层硅胶柱和活性炭柱对萃取提取物进行净化、洗脱,得到二噁英测试样品。用同位素稀释-高分辨气相色谱-质谱联用仪分析样品中二噁英的含量。考察两种提取方法及不同氯代数对15种^(13)C-2,3,7,8-PCDD/Fs回收率的影响,比较两种方法的准确度和精密度。结果表明,ASE和SE对15种^(13)C-2,3,7,8-PCDD/Fs的回收率分别为54.3%~113.0%和28.3%~77.7%,实测废线路板中二噁英毒性当量(Toxic equivalent quangtity,TEQ)分别为0.075 ng TEQ/kg和0.266 ng TEQ/kg。在方法精密度允许范围内,ASE相对具有简单快速、溶剂用量少和准确的优势。
