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  • Articles  (1,257)
  • 550 - Earth sciences  (1,255)
  • Lipids
  • 2005-2009  (1,257)
  • 2006  (1,257)
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  • Articles  (1,257)
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  • 2005-2009  (1,257)
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  • 1
    Publication Date: 2021-05-19
    Description: The boutargue is the salty and dried ovary of the mullet (Mugil cephalus) from Nouakchott (Mauritania) and Tunis (Tunisia). In order to know the nutritional quality of the boutargue, we have used an analytic analysis and dosages of lipids and their fat acids. For this study, we used two different methods of extraction of the lipids: method of Folch modified by Bligh and Dyer and the method of Soxhlet. These experiences show that the boutargue of mullet is rich in lipids, 30.9% in Nouakchott (Atlantic Ocean) and 27,4% in Tunis (Mediterranean Sea). The boutargue is with good nutritional quality. Indeed, each gram of boutargue contains 28,1 mg of fatty acids in Nouakchott and 19,7 mg in Tunisia. Theses fatty acids are subdivide in 3 essential groups: - Fatty acid saturated 17,9% in Atlantic Ocean and 2,8% in Mediterranean Sea. - Fatty acid monounsaturated 39, 4% in Atlantic Ocean and 41,4% in Mediterranean Sea. - Fatty acids polyunsaturated 28, 8% in Atlantic Ocean and 39 % in Mediterranean Sea. The quantity of lipids in Atlantic Ocean boutargue is superior to Mediterranean Sea boutargue but the quality of lipids in Mediterranean Sea boutargue is superior to Atlantic Ocean boutargue
    Description: تمثل البطارخ بيض سمك البوري (Mugil cephalus) المملحة و المجففة لمنطقتي نواكشوط (موريتانيا) و تونس (تونس). لمعرفة الجوانب البيوكيميائية و الغذائية لهذه البطارخ، قمنا بدراسة تحليلية كمية و كيفية للدهنيات. فاستخدمنا طريقتين مختلفتين لاستخلاص الدهون، هما طريقة فولش المعدلة من طرف بليغر ودير و طريقة سوكسلي. تبين أن البطارخ غنية بالدهنيات30,9 % بمنطقة نواكشوط (المحيط الأطلسي) و27,4 % بمنطقة تونس (البحر الأبيض المتوسط). يحتوي كل غرام من بطارخ منطقة نواكشوط على 28,1 ملغ من الأحماض الدهنية بينما لا تتعدى هذه النسبة 19,7 ملغ من الأحماض الدهنية ببطارخ منطقة تونس. تنقسم هذه الأحماض الى ثلاث مجموعات أساسية مختلفة كما وكيفا وهي: - الأحماض الدهنية المشبعة تصل إلى17,9 % ببطارخ المحيط الأطلسي بينما لا تتجاوز2,8 % ببطارخ البحر الأبيض المتوسط. - الأحماض الدهنية أحادية عدم التشبع بنسبة تصل إلى %39,4 ببطارخ المحيط الأطلسي بينما ترتفع هذه النسبة إلى 41,4 % ببطارخ البحر الأبيض المتوسط. - الأحماض الدهنية متعددة عدم التشبع بنسبة تصل إلى 28,8 % ببطارخ المحيط الأطلسي بينما ترتفع هذه النسبة إلى39 %.ببطارخ البحر الأبيض المتوسط. لقد بينت هذه الدراسة أن بطارخ المحيط الأطلسي﴿ نواكشوط- موريتانيا﴾، توجد بها نسبة من الدهنيات أكثر من نظيرتها بالبحر الأبيض المتوسط ﴿تونس- تونس﴾، بينما تمتاز هذه الأخيرة ﴿بطارخ البحر الأبيض المتوسط﴾ بجودة أكثر لدهنياتها بالمقارنة مع الأولى ﴿ بطارخ المحيط الأطلسي﴾.
    Description: La boutargue est constituée par les ovaires salés et séchés des mulets à grosse tête (Mugil cephalus) de la région de Nouakchott (Mauritanie) et de la région de Tunis (Tunisie). Pour savoir la quantité et la qualité de lipides dans cette boutargue nous avons effectué des études analytiques et des dosages des lipides et des acides gras de ceux-ci. Nous avons procédé par deux méthodes d’extraction des lipides : la méthode de Folch modifiée par Bligh et Dyer et la méthode de Soxhlet . Ces expériences ont révélé que la boutargue est très riche en lipides : 30,9% dans la région de Nouakchott (Océan Atlantique) et 27,4% dans la région de Tunis (Mer Méditerranéenne) qu’il est de bonne qualité nutritionnelle et que chaque gramme de boutargue contient 28,1 mg des acides gras dans la région de Nouakchott et 19,7 mg dans la région de Tunis. Ils sont subdivisés en 3 groupes essentiels : - acides gras saturés 17,9% dans l’Océan Atlantique et 2,8% dans la Mer Méditerranéenne. - acides gras mono insaturés 39,4 % dans l’Océan Atlantique et 41,4% dans la Mer Méditerranée. - acides gras polyinsaturés 28,8% dans l’Océan Atlantique et 39 % dans la Mer Méditerranée. La quantité lipidique de la boutargue atlantique est supérieure à celle de la Méditerranée et la qualité de la boutargue Méditerrané est meilleure que celle de l’Atlantique.
    Description: Published
    Keywords: Boutargue ; Mauritania ; Tunisia ; Mugil cephalus ; Lipides ; Acides gras ; Mulet ; Fatty acids ; Nutritive value ; Lipids ; Comparative studies ; Fatty acids ; Lipids ; Nutritive value ; Dried fish
    Repository Name: AquaDocs
    Type: Journal Contribution , Refereed , Article
    Format: 270212 bytes
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  • 2
    Publication Date: 2022-05-26
    Description: A procedure is described for the collection of remote marine aerosol samples by high-volume filtration, cascade impaction, dry fallout collection and rain. Samples were analyzed quantitatively for five classes of naturally occurring lipids (n-alkanes, wax esters, fatty alcohols, sterols, and fatty acids) and polycyclic aromatic hydrocarbons (PAHs). Air samples (4,000-10,000 m3) were collected on glass fiber filters under automatic control. Rain samples of 1-5 L were collected on an event basis. Filters and rain samples were extracted with methylene chloride. The extracts were fractionated into discrete chemical classes by silca-gel absorption chromatography. The fractions were derivatized if necessary and analyzed by HRGC and HRGC/MS. A second fiter extraction was required for fatty acid salt analysis. Internal standards were used to quantify recoveries and concentrations. Mean recoveries relative to the internal standards were 96.5% for C12-C36 n-alkanes, 96.4% for C12-C30 n-fatty acids, 92.5% for C12-C30 n-fatty alcohols and 93.3% for cholesterol. Typical blanks and concentrations for remote marine aerosol and rain samples are described and compared with other methods used in coastal marine, rural and suburban sampling locations.
    Description: Prepared for the National Science Foundation under Grants OCE 77-12914 and OCE 81-11947 as part of the Sea-Air Exchange (SEAREX) Program.
    Keywords: Lipids ; Aerosols ; Marine
    Repository Name: Woods Hole Open Access Server
    Type: Technical Report
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  • 3
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
    Type: info:eu-repo/semantics/article
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  • 4
    Publication Date: 2020-02-12
    Description: An important question in geophysics is whether earthquakes (EQs) can be anticipated prior to their occurrence. Pre-seismic electromagnetic (EM) emissions provide a promising window through which the dynamics of EQ preparation can be investigated. However, the existence of precursory features in pre-seismic EM emissions is still debatable: in principle, it is difficult to prove associations between events separated in time, such as EQs and their EM precursors. The scope of this paper is the investigation of the pre-seismic EM activity in terms of complexity. A basic reason for our interest in complexity is the striking similarity in behavior close to irreversible phase transitions among systems that are otherwise quite different in nature. Interestingly, theoretical studies (Hopfield, 1994; Herz and Hopfield 1995; Rundle et al., 1995; Corral et al., 1997) suggest that the EQ dynamics at the final stage and neural seizure dynamics should have many similar features and can be analyzed within similar mathematical frameworks. Motivated by this hypothesis, we evaluate the capability of linear and non-linear techniques to extract common features from brain electrical activities and pre-seismic EM emissions predictive of epileptic seizures and EQs respectively. The results suggest that a unified theory may exist for the ways in which firing neurons and opening cracks organize themselves to produce a large crisis, while the preparation of an epileptic shock or a large EQ can be studied in terms of “Intermittent Criticality”.
    Keywords: 550 - Earth sciences
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  • 5
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
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  • 6
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    In:  Berichte der Deutschen Mineralogischen Gesellschaft : Beihefte zum European Journal of Mineralogy ; 18, 1
    Publication Date: 2020-02-12
    Description: Numerous factors control the topographic evolution of mountain belts. Crustal thickening, rock uplift rate, and denudational forcing doubtlessly interact, but the feedback mechanisms amongst these are disputed, because they operate over entirely different time scales. Cosmogenically-derived denudation rates cover time-scales of 10(3) to 10(5) years, providing a denudational tool that allows us to shed light on interactions between long-term topography-forming processes and short-term factors destroying topography. Prerequisites for the application of this method in presently uplifting and fast-eroding mountain belts like the Central Alps are an investigation of appropriate watershed sizes for systematic sampling. Denudation rates in Maggia tributaries of various sizes reveal that the trunk stream yields statistically the same denudation rate (0.85 ± 0.14 mm/yr) as the tributaries (0.74 ± 0.14 mm/yr). Therefore, sampling of large watersheds is a feasible approach. Denudation rates of watersheds from the Central Alps are amongst the highest ever measured in similar complex settings, ranging in mean from 0.27 ± 0.05 mm/yr for the Alpine foreland to 1.42 ± 0.4 mm/yr for the high crystalline Central Alps. The measured cosmogenic denudation rates are in good agreement with post-LGM lake infill rates; they are significantly higher than recent denudation rates from river loads. We attribute this discrepancy to differences in methodology and integration time scale. We will show that denudation is high in areas of high altitude and high relief. Furthermore, our data shows that denudation rates are low in areas of low rock uplift, and are high in areas of high rock uplift, respectively. It appears that rock uplift and denudation are intimately linked. It follows that either crustal thickening is generating rock uplift; the mountain belt reacts with erosional unloading. Alternatively, high precipitation and glaciers, most pronounced at high altitude, result in high denudation rates at these sites. Topography then would respond by increasing rock uplift.
    Keywords: 550 - Earth sciences
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  • 7
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    In:  GIS.business : das Magazin für Geoinformation
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
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  • 8
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    In:  Backbone of the Americas - Patagonia to Alaska (Mendoza, Argentina 2006)
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
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  • 9
    Publication Date: 2020-02-12
    Description: The Aral Sea Basin is a critical area for studying the influence of climate and anthropogenic impact on the development of hydrographic conditions in an endorheic basin. We present organic-walled dinoflagellate cyst analyses with a sampling resolution of 15 to 20 years from a core retrieved at Chernyshov Bay in the NW Large Aral Sea (Kazakhstan). Cysts are present throughout, but species richness is low (seven taxa). The dominant morphotypes are Lingulodinium machaerophorum with varied process length and Impagidinium caspienense, a species recently described from the Caspian Sea. Subordinate species are Caspidinium rugosum, Romanodinium areolatum, Spiniferites cruciformis, cysts of Pentapharsodinium dalei, and round brownish protoperidiniacean cysts. The chlorococcalean algae Botryococcus and Pediastrum are taken to represent freshwater inflow into the Aral Sea. The data are used to reconstruct salinity as expressed in lake level changes during the past 2000 years. We quantify and date for the first time prominent salinity variations from the northern part of the Large Aral Sea. During high lake levels, I. caspienense, representing brackish conditions with salinities of about 10–15 g kg− 1 or less, prevails. Assemblages dominated by L. machaerophorum document lake lowstands during approximately 0–425 AD (or 100? BC–425 AD), 920–1230 AD, 1500 AD, 1600–1650 AD, 1800 AD and since the 1960s. Because salinity in the Aral Sea is mostly controlled by meltwater discharges from the Syr Darya and Amu Darya rivers, we interpret changes in salinity levels as a proxy for temperature fluctuations in the Tien Shan Mountains that control snow melt. Significant erosion of marine Palaeogene and Neogene deposits in the hinterland, evidenced between 1230 AD and 1400 AD, is regarded as sheet-wash from shore. This is controlled by the low pressure system that develops over the Eastern Mediterranean and brings moist air to the Middle East and Central Asia during late spring and summer. We propose that the recorded environmental changes are related primarily to climate, but perhaps to a lesser extent by human-controlled irrigation activities. Our results documenting climate change in western Central Asia are fairly consistent with reports elsewhere from Central Asia.
    Keywords: 550 - Earth sciences
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  • 10
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    In:  Berichte der Deutschen Mineralogischen Gesellschaft : Beihefte zum European Journal of Mineralogy ; 18, 1
    Publication Date: 2020-02-12
    Keywords: 550 - Earth sciences
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