878 resultados para Augusto, Emperador de Roma, 63 a.C.-14 d.C.
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Considerada a melhor bibliografia de autores brasileiros do período colonial até o século XIX. Apresenta a biografia de cada autor e as obras por ele produzidas. A introdução narra os primórdios da tipografia no Brasil e o nascedouro das primeiras sociedades literárias no país. A obra tornou-se famosa e muito respeitada. Recebeu crítica quanto a ordem de entrada dos autores pelo prenome, costume de época. O autor colaborou em O Ateneu, O Mosaico, Anais Brasileiros de Medicina e Revista do IHGB.
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Peter Edwards writes on rural aquaculture: Myanmar revisited. Harvesting, traditional preservation and marketing of fishes of Chalan Beel, Bangladesh, by Galib, S.M. and Samad, M.A. Role of community in production and supply of larger, quality fingerlings, by Radheyshyam, De, H.K. and Saha, G.S. Can rice-fish farming provide food security in Bangladesh? by Ahmed, N. and Luong-Van, J. Nutritional and food security for rural poor through multi-commodity production from a lake of eastern Uttar Pradesh, by Singh, S.K. Emerging boost in Sri Lankan reservoir fish production: a case of adoption of past research findings, by Amarasinghe, U.S., Weerakoon, D.E.M., Athukorala, D.A. Farming the freshwater prawn Macrobrachium malcolmsonii, by Radheyshyam Breeding and seed production of butter catfish, Ompok pabda (Siluridae) at Kalyani Centre of CIFA, India, by Chakrabarti, P.P., Chakrabarty, N.M. and Mondal, S.C. Asia-Pacific Marine Finfish Aquaculture Magazine Use of fish in animal feeds: a fresh perspective National strategies for aquatic animal health management, by Mohan, C.V. NACA Newsletter.
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Executive Summary: The western National Coastal Assessment (NCA-West) program of EPA, in conjunction with the NOAA National Ocean Service (NOS), conducted an assessment of the status of ecological condition of soft sediment habitats and overlying waters along the western U.S. continental shelf, between the target depths of 30 and 120 m, during June 2003. NCA-West and NOAA/NOS partnered with the West Coast states (Washington (WA), Oregon (OR), and California (CA)), and the Southern California Coastal Water Research Project (SCCWRP) Bight ’03 program to conduct the survey. A total of 257 stations were sampled from Cape Flattery, WA to the Mexican border using standard methods and indicators applied in previous coastal NCA projects. A key study feature was the incorporation of a stratified-random sampling design with stations stratified by state and National Marine Sanctuary (NMS) status. Each of the three states was represented by at least 50 random stations. There also were a total of 84 random stations located within NOAA’s five NMSs along the West Coast including the Olympic Coast NMS (OCNMS), Cordell Bank NMS (CBNMS), Gulf of Farallones NMS (GFNMS), Monterey Bay NMS (MBNMS), and Channel Islands NMS (CINMS). Collection of flatfish via hook-and-line for fish-tissue contaminant analysis was successful at 50 EMAP/NCA-West stations. Through a collaboration developed with the FRAM Division of the Northwest Fisheries Science Center, fish from an additional 63 stations in the same region and depth range were also analyzed for fish-tissue contaminants. Bottom depth throughout the region ranged from 28 m to 125 m for most stations. Two slightly deeper stations from the Southern California Bight (SCB) (131, 134 m) were included in the data set. About 44% of the survey area had sediments composed of sands (< 20% silt-clay), about 47% was composed of intermediate muddy sands (20-80% silt-clay), and about 9% was composed of muds (> 80% silt-clay). The majority of the survey area (97%) had relatively low percent total organic carbon (TOC) levels of < 2%, while a small portion (< 1%) had high TOC levels (> 5%), in a range potentially harmful to benthic fauna. Salinity of surface waters for 92% of the survey area were > 31 psu, with most stations < 31 psu associated with the Columbia River plume. Bottom salinities ranged only between 31.6 and 34.4 psu. There was virtually no difference in mean bottom salinities among states or between NMS and non-NMS stations. Temperatures of surface water (range 8.5 -19.9 °C) and bottom water (range 5.8 -14.7 °C) averaged several degrees higher in CA in comparison to WA and OR. The Δσt index of watercolumn stratification indicated that about 31% of the survey area had strong vertical stratification of the water column. The index was greatest for waters off WA and lowest for CA waters. Only about 2.6 % of the survey area had surface dissolved oxygen (DO) concentrations ≤ 4.8 mg/L, and there were no values below the lower threshold (2.3 mg/L) considered harmful to the survival and growth of marine animals. Surface DO concentrations were higher in WA and OR waters than in CA, and higher in the OC NMS than in the CA sanctuaries. An estimated 94.3% of the area had bottom-water DO concentrations ≤ 4.8 mg/L and 6.6% had concentrations ≤ 2.3 mg/L. The high prevalence of DO from 2.3 to 4.8 mg/L (85% of survey area) is believed to be associated with the upwelling of naturally low DO water across the West Coast shelf. Mean TSS and transmissivity in surface waters (excluding OR due to sample problems) were slightly higher and lower, respectively, for stations in WA than for those in CA. There was little difference in mean TSS or transmissivity between NMS and non-NMS locations. Mean transmissivity in bottom waters, though higher in comparison to surface waters, showed little difference among geographic regions or between NMS and non-NMS locations. Concentrations of nitrate + nitrite, ammonium, total dissolved inorganic nitrogen (DIN) and orthophosphate (P) in surface waters tended to be highest in CA compared to WA and OR, and higher in the CA NMS stations compared to CA non-sanctuary stations. Measurements of silicate in surface waters were limited to WA and CA (exclusive of the SCB) and showed that concentrations were similar between the two states and approximately twice as high in CA sanctuaries compared to OCNMS or nonsanctuary locations in either state. The elevated nutrient concentrations observed at CA NMS stations are consistent with the presence of strong upwelling at these sites at the time of sampling. Approximately 93% of the area had DIN/P values ≤ 16, indicative of nitrogen limitation. Mean DIN/P ratios were similar among the three states, although the mean for the OCNMS was less than half that of the CA sanctuaries or nonsanctuary locations. Concentrations of chlorophyll a in surface waters ranged from 0 to 28 μg L-1, with 50% of the area having values < 3.9 μg L-1 and 10% having values > 14.5 μg L-1. The mean concentration of chlorophyll a for CA was less than half that of WA and OR locations, and concentrations were lowest in non-sanctuary sites in CA and highest at the OCNMS. Shelf sediments throughout the survey area were relatively uncontaminated with the exception of a group of stations within the SCB. Overall, about 99% of the total survey area was rated in good condition (<5 chemicals measured above corresponding effect range low (ERL) concentrations). Only the pesticides 4,4′-DDE and total DDT exceeded corresponding effect range-median (ERM) values, all at stations in CA near Los Angeles. Ten other contaminants including seven metals (As, Cd, Cr, Cu, Hg, Ag, Zn), 2-methylnaphthalene, low molecular weight PAHs, and total PCBs exceeded corresponding ERLs. The most prevalent in terms of area were chromium (31%), arsenic (8%), 2-methylnaphthalene (6%), cadmium (5%), and mercury (4%). The chromium contamination may be related to natural background sources common to the region. The 2-methylnaphthalene exceedances were conspicuously grouped around the CINMS. The mercury exceedances were all at non-sanctuary sites in CA, particularly in the Los Angeles area. Concentrations of cadmium in fish tissues exceeded the lower end of EPA’s non-cancer, human-health-risk range at nine of 50 EMAP/NCA-West and nine of 60 FRAM groundfish-survey stations, including a total of seven NMS stations in CA and two in the OCNMS. The human-health guidelines for all other contaminants were only exceeded for total PCBs at one station located in WA near the mouth of the Columbia River. Benthic species richness was relatively high in these offshore assemblages, ranging from 19 to 190 taxa per 0.1-m2 grab and averaging 79 taxa/grab. The high species richness was reflected over large areas of the shelf and was nearly three times greater than levels observed in estuarine samples along the West Coast (e.g NCA-West estuarine mean of 26 taxa/grab). Mean species richness was highest off CA (94 taxa/grab) and lower in OR and WA (55 and 56 taxa/grab, respectively). Mean species richness was very similar between sanctuary vs. non-sanctuary stations for both the CA and OR/WA regions. Mean diversity index H′ was highest in CA (5.36) and lowest in WA (4.27). There were no major differences in mean H′ between sanctuary vs. nonsanctuary stations for both the CA and OR/WA regions. A total of 1,482 taxa (1,108 to species) and 99,135 individuals were identified region-wide. Polychaetes, crustaceans and molluscs were the dominant taxa, both by percent abundance (59%, 17%, 12% respectively) and percent species (44%, 25%, 17%, respectively). There were no major differences in the percent composition of benthic communities among states or between NMSs and corresponding non-sanctuary sites. Densities averaged 3,788 m-2, about 30% of the average density for West Coast estuaries. Mean density of benthic fauna in the present offshore survey, averaged by state, was highest in CA (4,351 m-2) and lowest in OR (2,310 m-2). Mean densities were slightly higher at NMS stations vs. non-sanctuary stations for both the CA and OR/WA regions. The 10 most abundant taxa were the polychaetes Mediomastus spp., Magelona longicornis, Spiophanes berkeleyorum, Spiophanes bombyx, Spiophanes duplex, and Prionospio jubata; the bivalve Axinopsida serricata, the ophiuroid Amphiodia urtica, the decapod Pinnixa occidentalis, and the ostracod Euphilomedes carcharodonta. Mediomastus spp. and A. serricata were the two most abundant taxa overall. Although many of these taxa have broad geographic distributions throughout the region, the same species were not ranked among the 10 most abundant taxa consistently across states. The closest similarities among states were between OR and WA. At least half of the 10 most abundant taxa in NMSs were also dominant in corresponding nonsanctuary waters. Many of the abundant benthic species have wide latitudinal distributions along the West Coast shelf, with some species ranging from southern CA into the Gulf of Alaska or even the Aleutians. Of the 39 taxa on the list of 50 most abundant taxa that could be identified to species level, 85% have been reported at least once from estuaries of CA, OR, or WA exclusive of Puget Sound. Such broad latitudinal and estuarine distributions are suggestive of wide habitat tolerances. Thirteen (1.2%) of the 1,108 identified species are nonindigenous, with another 121 species classified as cryptogenic (of uncertain origin), and 208 species unclassified with respect to potential invasiveness. Despite uncertainties of classification, the number and densities of nonindigenous species appear to be much lower on the shelf than in the estuarine ecosystems of the Pacific Coast. Spionid polychaetes and the ampharetid polychaete Anobothrus gracilis were a major component of the nonindigenous species collected on the shelf. NOAA’s five NMSs along the West Coast of the U.S. appeared to be in good ecological condition, based on the measured indicators, with no evidence of major anthropogenic impacts or unusual environmental qualities compared to nearby nonsanctuary waters. Benthic communities in sanctuaries resembled those in corresponding non-sanctuary waters, with similarly high levels of species richness and diversity and low incidence of nonindigenous species. Most oceanographic features were also similar between sanctuary and non-sanctuary locations. Exceptions (e.g., higher concentrations of some nutrients in sanctuaries along the CA coast) appeared to be attributable to natural upwelling events in the area at the time of sampling. In addition, sediments within the sanctuaries were relatively uncontaminated, with none of the samples having any measured chemical in excess of ERM values. The ERL value for chromium was exceeded in sediments at the OCNMS, but at a much lower percentage of stations (four of 30) compared to WA and OR non-sanctuary areas (31 of 70 stations). ERL values were exceeded for arsenic, cadmium, chromium, 2- methylnaphthalene, low molecular weight PAHs, total DDT, and 4,4′-DDE at multiple sites within the CINMS. However, cases where total DDT, 4,4′-DDE, and chromium exceeded the ERL values were notably less prevalent at CINMS than in non-sanctuary waters of CA. In contrast, 2-methylnaphthalene above the ERL was much more prevalent in sediments at the CINMS compared to non-sanctuary waters off the coast of CA. While there are natural background sources of PAHs from oil seeps throughout the SCB, this does not explain the higher incidence of 2-methylnaphthalene contamination around CINMS. Two stations in CINMS also had levels of TOC (> 5%) potentially harmful to benthic fauna, though none of these sites exhibited symptoms of impaired benthic condition. This study showed no major evidence of extensive biological impacts linked to measured stressors. There were only two stations, both in CA, where low numbers of benthic species, diversity, or total faunal abundance co-occurred with high sediment contamination or low DO in bottom water. Such general lack of concordance suggests that these offshore waters are currently in good condition, with the lower-end values of the various biological attributes representing parts of a normal reference range controlled by natural factors. Results of multiple linear regression, performed using full model procedures to test for effects of combined abiotic environmental factors, suggested that latitude and depth had significant influences on benthic variables regionwide. Latitude had a significant inverse influence on all three of the above benthic variables, i.e. with values increasing as latitude decreased (p< 0.01), while depth had a significant direct influence on diversity (p < 0.001) and inverse effect on density (p <0.01). None of these variables varied significantly in relation to sediment % fines (at p< 0.1), although in general there was a tendency for muddier sediments (higher % fines) to have lower species richness and diversity and higher densities than coarser sediments. Alternatively, it is possible that for some of these sites the lower values of benthic variables reflect symptoms of disturbance induced by other unmeasured stressors. The indicators in this study included measures of stressors (e.g., chemical contaminants, eutrophication) that are often associated with adverse biological impacts in shallower estuarine and inland ecosystems. However, there may be other sources of humaninduced stress in these offshore systems (e.g., bottom trawling) that pose greater risks to ambient living resources and which have not been captured. Future monitoring efforts in these offshore areas should include indicators of such alternative sources of disturbance. (137pp.) (PDF contains 167 pages)
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O Codigo Brasiliense reúne as primeiras leis promulgadas em solo brasileiro, desde o ano de 1808 até 1822, abrangendo todo o Período Joanino. Essas leis fazem parte dos primeiros impressos produzidos pela Impressão Regia, possuindo, portanto, a característica de incunábulos brasileiros. Segundo pesquisa da John Carter Brown Library, existem várias versões tipograficamente diferentes, não encadernadas, impressas possivelmente em Lisboa. As diferenças podem ser detectadas, particularmente, pela capital ornamentada E, cuja variante digitalizada encontra-se no site daquela instituição. É muito raro encontrar em um mesmo acervo os 3 volumes que compõem o Código e, mais ainda, encontrar exemplares completos. É obra importantíssima para a memória brasileira.
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As negociações entre Portugal e Holanda a respeito da devolução dos territórios portugueses ocupados se desenvolveram ao longo de um decênio. As propostas iniciais de Portugal referiam-se aos territórios ocupados pelos holandeses na África e no Maranhão. Estão no raríssimo folheto.
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der="0" alt="" hspace="8" width="102" height="144" align="left" />MicrosoftVisualC十十6.0作为Microsoft Visual Studio的重要组成部分,包含了迄今为止功能最为强大的基于Windows的应用框架,在同类产品中处于领先地位。VisualC十十6.0是Microsoft迄今为止最全面、最完善的程序开发工具,为了适应各种编程风格,该软件提供了各种各样的辅助工具,在发挥编程能力和提高灵活性方面达到了空前的水平。与以往VisualC十十的各种版本相比较,VisualC十十6.0在编程环境、程序语言技术等方面做了许多改进,从而使VisualC十十更加适合专业程序员快速进行应用程序的开发。
本书内容丰富、图文并茂,是一本适合各种读者学习VisualC十十6.0的优秀参考书。
目 录
第一章 VisualC十十6.0简介及安装
1.1VisualC十十6.0新特性
1.2viSualC十十6.0开发环境简介
1.3如何学习使用VisualC十十6.0
1.4VisualC十十6.0的安装
第二章 走进C十十的世界
2.1类和对象的简介
2.2继承和多态性――一个具体的例子
2.3内嵌对象
2.4在栈中申请对象
2.5全程对象的申请
2.6对象之间的相互关系――指针数据成员
2.7this指针的使用
2.8对指针的引用
2.9友元类和友元函数
2.10静态类成员
2.11重载运算符
2.12从代码中分离出类定义
2.13匈牙利表示法
第三章 VisualC十十6.0的编程环境
3.1VisualC十十6.0主窗口
3.2VisualC十十6.0工具栏
3.3VisualC十十6.0菜单栏
3.4项目与项目工作区
3.5资源与资源编辑器
第四章 编一个最简单的VC十十程序
4.1什么是AppWizard?
4.2迎接你的第一个AppWizard程序
4.3“Iamaprogrammer.”在哪儿?
第五章 程序框架入门
5.1一个简化过的程序框架
5.2WinMain():第一个动作
5.3登记窗口类
5.4创建一个窗口
5.5显示窗口
5.6显示出那条消息
5.7窗口类与窗口对象
第六章 消息循环
6.1在消息循环中兜圈子
6.2对事件做出响应:WindowFun()
6.3响应不同的消息
6.4现在你还跟得上吗?
6.5设备界面进行交互
第七章 精通程序框架
7.1WinMain()函数在哪儿?
7.2应用程序框架和源文件
7.3工具条、状态条和打印等选项
7.4程序的控制流程
第八章 使用classWizard编程
8.1使用ClassWizard添加消息处理函数
8.2classWizard功能介绍
8.3传送鼠标消息
8.4保存鼠标绘图的信息
第九章 视图与文档
9.1Document-View模式
9.2从视图中分离出文档
9.3保存文档
9.4再访MyProg2.cpp
第十章 对象连接与嵌入(OLE)及其自动化
10.1公共对象模式(COM)
10.2类厂(classfactory)
10.3OLE自动化
10.4IDispatch接口
第十一章 动态连接库(DLLs)
11.1为什么使用DLL
11.2传统的DLL
11.3MFC库DLL
11.4MyProg4A――编写自己的类库扩展DLL
11.5MyProg4B――使用MFC库扩展DLL
11.6资源访问
第十二章 图形设备接口
12.1设备环境类
12.2GDI对象
12.3Windows的颜色映射
12.4映射方式
12.5字体
12.6MyProg3例程序
12.7MyProg3B程序
12.8MyPr0g3C例程序――使用CScrollView
第十三章 对话框
13.1在状态条上显示对话控件的帮助信息
13.2利用Fi1eOpen通用对话框打开多个文件
13.3定制通用文件对话框
13.4扩展和缩减一个对话框
13.5显示一个模式或无模式对话框
13.6编写定制的DDX/DDV例程
第十四章 剖析工具Spy十+
14.1窗体
14.2消息
14.3进程与线程
第十五章 代码调试
15.1TRACE
15.2调试框架
15.3自我诊断
15.4调试代码的作用
15.5用Dump()显示对象的信息
15.6检查内存
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(PDF contains 63 pages.)
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The synthesis of a GSK 2(nd) generation inhibitor of the hepatitis C virus, by enantioselective 1,3-dipolar cycloaddition between a leucine derived iminoester and tert-butyl acrylate, was studied. The comparison between silver(I) and gold(I) catalysts in this reaction was established by working with chiral phosphoramidites or with chiral BINAP. The best reaction conditions were used for the total synthesis of the hepatitis C virus inhibitor by a four step procedure affording this product in 99% ee and in 63% overall yield. The origin of the enantioselectivity of the chiral gold(I) catalyst was justified according to DFT calculations, the stabilizing coulombic interaction between the nitrogen atom of the thiazole moiety and one of the gold atoms being crucial.
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Sustainable aquaculture GLOBALG.A.P. standard in Thai shrimp farms: Mission (im)possible? p.4 Leepaisomboon, T., Chuchird, N., Limsuwan, C., Steenbruggen, E.R., and Mungkung, R. The Victorian trout industry & the bushfires p.6 Mosig, J. Small-scale aquaculture in the Ayeyarwady Delta, Myanmar p.10 Edwards, P. The history, status, and future prospects of monosex tilapia culture in Thailand p.18 Belton, B., Turongruang, D., Bhujel, R. and Little, D.C. Mangroves of Nakhon Si Thammarat Province in southern Thailand: Species diversity, community structure and current status p.20 By Amarasinghe, M.D., Dulyapurk, V., Taparhudee, W., Yoonpundh, R. and Jumnongsong, S. Research and farming techniques Induced breeding of pacu (Piaractus brachypomus) in captivity with pituitary extract p.23 Chattarjee, N.R. and Mazumdar, B. Aquatic animal health Fumonisins - mycotoxins of increasing importance in fish! p. 24 Griessler, K. and Encarnação, P. Genetics and biodiversity Microsatellite DNA markers, a fisheries perspective. Part 1: The nature of microsatellites p.27 Sekar, M., Suresh, E., Kumar, N.S., Nayak, S.K., Balakrishna, C. Asia-Pacific Marine Finfi sh Aquaculture Magazine Formulated feed for tiger grouper grow-out p.30 Rachmansyah, Usman, Palinggi, N.N. and Williams, K. NACA Newsletter 36
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Sustainable aquaculture Contrasting community management and revenue sharing practices of culture-based fisheries in Lao PDR Saphakdy, B., Phomsouvanh, A., Davy, B., Nguyen, T.T.T. and De Silva, S.S.; Floodplain aquaculture in Begumgonj: New horizon for rural livelihoods in Bangladesh Hossain, M. S.; Promoting small-scale inland aquaculture in Papua New Guinea Edwards, P.; Group approach to shrimp farming: The key to sustainability Kumaran, M.; Research and farming techniques Native catfish culture - a technology package for fish farmers Haniffa, M. A.; An assessment on the influence of salinity in the growth of black clam (Villorita cyprinoides) in cages in Cochin estuary with a special emphasis on the impact of Thennermukkom Salinity Barrier Arun, A. U.; Aquatic animal health EUS in Asia and Africa: Stimulus for regional initiatives!!! Mohan, C.V. Marine Finfish Aquaculture Network Offshore opportunities for artisanal aquaculture Stock, C.; Grouper aquaculture in Brazil Sanches, E.G. and Von Seckendorff, R.W. NACA Newsletter
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Sex ratio and fecundity variations of Chrysichthys nigrodigitatus and Chrysichthys walkeri from Asejire Lake (Nigeria) were examined. The Logarithm transformation of weight (W) against standard length (SL) gave a straight-line graph represented by the following equations: 1) C. nigrodigitatus LogW =-0.66 + 2.13 Log SL; = 0.854; (P < 0.001) n = 209; 2) C. walkeri LogW = -1.23 + 2.63 Log SL; = 0.759; (P < 0.001) n = 237. Males were generally more than females in both species. The ratio of males:females was higher in C. nigrodigitatus (1:0.18) than in C. walkeri (1:0.8). C. walkeri attained sexual maturity at a smaller size of 20.0 g (12.0 cm Standard Length) compared with C. nigrodigitatus maturity size of 45.0 g (14.0 cm Standard Length). Relative fecundity was not dependent on body weight and standard length for C. walkeri but it was significant at P < 0.05 and P < 0.01 respectively for C. nigrodigitatus
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Redox-active ruthenium complexes have been covalently attached to the surface of a series of natural, semisynthetic and recombinant cytochromes c. The protein derivatives were characterized by a variety of spectroscopic techniques. Distant Fe^(2+) - Ru^(3+) electronic couplings were extracted from intramolecular electron-transfer rates in Ru(bpy)_2(im)HisX (where X= 33, 39, 62, and 72) derivatives of cyt c. The couplings increase according to 62 (0.0060) < 72 (0.057) < 33 (0.097) < 39 (0.11 cm^(-1)); however, this order is incongruent with histidine to heme edge-edge distances [62 (14.8) > 39 (12.3) > 33 (11.1) > =72 (8.4 Å)]. These results suggest the chemical nature of the intervening medium needs to be considered for a more precise evaluation of couplings. The rates (and couplings) correlate with the lengths of a-tunneling pathways comprised of covalent bonds, hydrogen bonds and through-space jumps from the histidines to the heme group. Space jumps greatly decrease couplings: one from Pro71 to Met80 extends the σ-tunneling length of the His72 pathway by roughly 10 covalent bond units. Experimental couplings also correlate well with those calculated using extended Hiickel theory to evaluate the contribution of the intervening protein medium.
Two horse heart cyt c variants incorporating the unnatural amino acids (S)-2- amino-3-(2,2'-bipyrid-6-yl)-propanoic acid (6Bpa) and (S)-2-amino-3-(2,2'-bipyrid-4-yl)propanoic acid ( 4Bpa) at position 72 have been prepared using semisynthetic protocols. Negligible perturbation of the protein structure results from this introduction of unnatural amino acids. Redox-active Ru(2,2'-bipyridine)_2^(2+) binds to 4Bpa72 cyt c but not to the 6Bpa protein. Enhanced ET rates were observed in the Ru(bpy)_2^(2+)-modified 4Bpa72 cyt c relative to the analogous His72 derivative. The rapid (< 60 nanosecond) photogeneration of ferrous Ru-modified 4Bpa72 cyt c in the conformationally altered alkaline state demonstrates that laser-induced ET can be employed to study submicrosecond protein-folding events.
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Semisynthesis of horse heart cytochrome c and site-directed mutagenesis of Saccharomyces cerevisiae (S. c.) iso-1-cytochrome c have been utilized to substitute Ala for the cytochrome c heme axial ligand Met80 to yield ligand-binding proteins (horse heart Ala80cyt c and S.c. Ala80cyt c) with spectroscopic properties remarkably similar to those of myoglobin. Both species of Fe(II)Ala80cyt c form exceptionally stable dioxygen complexes with autoxidation rates 10-30x smaller and O2 binding constants ~ 3x greater than those of myoglobin. The resistance of O2-Fe(II)Ala80cyt c to autoxidation is attributed in part to protection of the heme site from solvent as exhibited by the exceptionally slow rate of CO binding to the heme as well as the low quantum yield of CO photodissociation.
UV/vis, EPR, and paramagnetic NMR spectroscopy indicate that at pH 7 the Fe(III)Ala80cyt c heme is low-spin with axial His-OH- coordination and that below pH ~6.5, Fe(III)Ala80cyt cis high-spin with His-H2O heme ligation. Significant differences in the pH dependence of the 1H NMR spectra of S.c. Fe(III)Ala80cyt c compared to wild-type demonstrate that the axial ligands influence the conformational energetics of cytochrome c.
1H NMR spectroscopy has been utilized to determine the solution structure of the cyanide derivative of S.c. Fe(III)Ala80cyt c. 82% of the resonances in the 1H NMR spectrum of S.c. CN-Fe(III)Ala80cyt c have been assigned through 1D and 2D experiments. The RMSD values after restrained energy minimization of the family of 17 structures obtained from distance geometry calculations are 0.68 ± 0.11 Å for the backbone and 1.32 ± 0.14 Å for all heavy atoms. The solution structure indicates that a tyrosine in the "distal" pocket of CN-Fe(III)Ala80cyt c forms a hydrogen bond with the Fe(III)-CN unit, suggesting that it may play a role analogous to that of the distal histidine in myoglobin in stabilizing the dioxygen adduct.
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The Chesapeake and Delaware Canal is a man-made waterway connecting the upper Chesapeake Bay with the Delaware Bay. It started in 1829 as a private barge canal with locks, two at the Delaware end, and one at the Chesapeake end. For the most part, natural tidal and non-tidal waterways were connected by short dredged sections to form the original canal. In 1927, the C and D Canal was converted to a sea-level canal, with a controlling depth of 14 feet, and a width of 150 feet. In 1938 the canal was deepened to 27 feet, with a channel width of 250 feet. Channel side slopes were dredged at 2.5:1, thus making the total width of the waterway at least 385 feet in those segments representing new cuts or having shore spoil area dykes rising above sea level. In 1954 Congress authorized a further enlargement of the Canal to a depth of 35 feet and a channel width of 450 feet. (pdf contains 27 pages)
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Utilization of the heavy isotope of nitrogen as a tracer has found numerous applications in soil biology. It allows better definition of different stages of the nitrogen cycle, in particular the immobilization-mineralization cycle. In this work, the authors report the results of calculations of natural isotope ratios of nitrogen in samples of water, soil and vegetation prevailing in Dombes and discuss the possibilities of errors and coefficients of fractionation.