scholarly journals Maltese chert: An archaeological perspective on raw material and lithic technology in the central Mediterranean

2021 ◽  
Author(s):  
Huw Groucutt
Keyword(s):  
Lithic Technology ◽  
Raw Material ◽  
Archaeological Record ◽  
Distribution Characteristics ◽  
Central Mediterranean ◽  
The West ◽  
High Quality ◽  
High Frequencies ◽  
Maltese Islands ◽  
Megalithic Temples

The Maltese islands are renowned for their prehistoric archaeological record, particularly thefamous megalithic ‘temples’ and associated ceramics and artwork. The temples were built bya society lacking metal technology, who relied on stone and organic materials. Knapped stonetool (lithic) technology, to produce sharp edged tools for tasks like cutting, hide working, andwood shaping involved the use of both imported obsidian and high-quality chert – offeringinsights into themes of exchange and connectivity – and local chert. The local chert hasgenerally been described as low-quality, yet relatively little research has been conducted on its distribution, characteristics, and use. In this paper I report a survey of chert sources, identifying a wider distribution of chert outcrops along the west coast of Malta than previously discussed. Some general macroscopic properties are outlined, while there are also aspects of variability in the chert sources. Knapping experiments were then conducted on samples of chert collected, allowing clarification of its characteristics. These observations are used to offer some insightsinto lithic technology in Neolithic and Temple Period Malta, such as the hypothesis that the high frequencies of multidirectional flake production and subsequent ‘scraper retouch’ reflect adaptations to the characteristics of local chert.

Gravels and Travels: A Comment on Andrefsky's “Cascade Phase Lithic Technology”

1997 ◽  
Vol 18 (1) ◽  
pp. 67-81 ◽  
Author(s):  
Kenneth C. Reid
Keyword(s):  
Lithic Technology ◽  
Field Studies ◽  
Raw Material ◽  
Snake River ◽  
Long Distance ◽  
High Quality ◽  
The Holocene ◽  
Lithic Assemblages

The presence of chert in mid-Holocene lithic assemblages along the Snake River has been attributed to long distance mobility, with the material introduced in bifacial form to the canyons from upland quarries. Geological field studies, however, show that chert, argillite, and quartzite are common in terrace and alluvial gravels along the lower Snake River. These lithologies probably provided a major source of high quality raw material for populations wintering near the river throughout the Holocene.

TECHNOLOGICAL ASPECTS OF HIGH QUALITY RAW MATERIAL OBTAINING FOR PECTIN PRODUCTION

1970 ◽  
pp. 47-50
Author(s):  
I. A. Ilina ◽  
I. A. Machneva ◽  
E. S. Bakun
Keyword(s):  
Raw Materials ◽  
Thermal Characteristics ◽  
Environmental Safety ◽  
Raw Material ◽  
High Quality ◽  
Temperature Conductivity ◽  
Drying Temperature ◽  
Plant Raw Materials ◽  
Gel Forming Ability

  The article is devoted to the study of the chemical composition, physical and thermal-pfysical characteristics of damp apple pomaces and the identifying patterns of influence of drying temperature the functional composition and gel-forming ability of pectin. The research is aimed at obtaining initial data for the subsequent calculation of the main technological, hydro-mechanical, thermal, structural and economic characteristics of devices for drying the plant raw materials, ensuring the environmental safety and high quality of pectin-containing raw materials, the reducing heat and energy costs. As a result of the study of the thermal characteristics of apple pomaces, the critical points (temperature conductivity – 16.5 x 10-8 m2/s, thermal conductivity – 0.28 W/m K, heat capacity – 1627 j/(kg K)) at a humidity of 56 % are determined, which characterizing the transition from the extraction of weakly bound moisture to the extraction of moisture with strong bonds (colloidal, adsorption). It was found that the pomaces obtained from apples of late ripening have a higher content of solids (21-23 %), soluble pectin and protopectin (2.5-4.5 %). Dried pomaces obtained from apple varieties of late ripening contain up to 25 % pectin, which allow us to recommend them as a source of raw materials for the production of pectin. The optimum modes of preliminary washing of raw materials are offered, allowing to the remove the ballast substances as much as possible. It is established that when the drying temperature increases, the destructive processes are catalyzed: the strength of the pectin jelly and the uronide component and the degree of pectin esterification are reduced. The optimum drying temperature of damp apple pomaces is 80 0C, at which the quality of pectin extracted from the dried raw materials is maintained as much as possible. It is shown that the most effective for the pectin production is a fraction with a particle size of 3-5 mm, which allow us to extract up to 71 % of pectin from raw materials.

scholarly journals Air–Sea Interaction in the Central Mediterranean Sea: Assessment of Reanalysis and Satellite Observations

2021 ◽  
Vol 13 (11) ◽  
pp. 2188
Author(s):  
Salvatore Marullo ◽  
Jaime Pitarch ◽  
Marco Bellacicco ◽  
Alcide Giorgio di Sarra ◽  
Daniela Meloni ◽  
...  
Keyword(s):  
Heat Flux ◽  
Mediterranean Sea ◽  
Seasonal Cycle ◽  
Heat Fluxes ◽  
Meteorological Variables ◽  
Central Mediterranean ◽  
High Quality ◽  
Central Mediterranean Sea ◽  
In Situ Observations

Air–sea heat fluxes are essential climate variables, required for understanding air–sea interactions, local, regional and global climate, the hydrological cycle and atmospheric and oceanic circulation. In situ measurements of fluxes over the ocean are sparse and model reanalysis and satellite data can provide estimates at different scales. The accuracy of such estimates is therefore essential to obtain a reliable description of the occurring phenomena and changes. In this work, air–sea radiative fluxes derived from the SEVIRI sensor onboard the MSG satellite and from ERA5 reanalysis have been compared to direct high quality measurements performed over a complete annual cycle at the ENEA oceanographic observatory, near the island of Lampedusa in the Central Mediterranean Sea. Our analysis reveals that satellite derived products overestimate in situ direct observations of the downwelling short-wave (bias of 6.1 W/m2) and longwave (bias of 6.6 W/m2) irradiances. ERA5 reanalysis data show a negligible positive bias (+1.0 W/m2) for the shortwave irradiance and a large negative bias (−17 W/m2) for the longwave irradiance with respect to in situ observations. ERA5 meteorological variables, which are needed to calculate the air–sea heat flux using bulk formulae, have been compared with in situ measurements made at the oceanographic observatory. The two meteorological datasets show a very good agreement, with some underestimate of the wind speed by ERA5 for high wind conditions. We investigated the impact of different determinations of heat fluxes on the near surface sea temperature (1 m depth), as determined by calculations with a one-dimensional numerical model, the General Ocean Turbulence Model (GOTM). The sensitivity of the model to the different forcing was measured in terms of differences with respect to in situ temperature measurements made during the period under investigation. All simulations reproduced the true seasonal cycle and all high frequency variabilities. The best results on the overall seasonal cycle were obtained when using meteorological variables in the bulk formulae formulations used by the model itself. The derived overall annual net heat flux values were between +1.6 and 40.4 W/m2, depending on the used dataset. The large variability obtained with different datasets suggests that current determinations of the heat flux components and, in particular, of the longwave irradiance, need to be improved. The ENEA oceanographic observatory provides a complete, long-term, high resolution time series of high quality in situ observations. In the future, more similar sites worldwide will be needed for model and satellite validations and to improve the determination of the air–sea exchange and the understanding of related processes.

Dependency in Africa: Stages of African Political Economy

1983 ◽  
Vol 9 (2) ◽  
pp. 229-247 ◽  
Author(s):  
Amechi Okolo
Keyword(s):  
Political Economy ◽  
International System ◽  
Raw Material ◽  
The West ◽  
Cheap Labour ◽  
History Of ◽  
The Common ◽  
First Contact ◽  
The Impact ◽  
The Relationship

This paper traces the history of the relationship between Africa and the West since their first contact brought about by the outward thrust of the West, under the impetus of rising capitalism, in search of cheap labour and cheap raw material for its industries and expanding markets for its industrial products, both of which could be better ensured through domination and exploitation. The paper identifies five successive stages that African political economy has passed through under the impact of this relationship, each phase qualitatively different from the other but all having the common characteristic of domination-dependence syndrome, and each phase having been dictated by the dynamics of capitalism in different eras and by the dominant forces in the changing international system. Its finding is that the way to the latest stage, the dependency phase, was paved by the progressive proletarianization of the African peoples and the maintenance of an international peonage system. It ends by indicating the direction in which Africa can make a beginning to break out of dependency and achieve liberation.

Ball-Milling Graphite Used for Synthesis of Biocompatible Blue Luminescent Graphene Quantum Dots

2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Zhou J ◽  
◽  
Dong Y ◽  
Ma Y ◽  
Zhang T ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Ball Milling ◽  
Graphene Quantum Dots ◽  
Raw Material ◽  
Hydroxyl Groups ◽  
High Quality ◽  
Widespread Application ◽  
Force Microscopy ◽  
Atomic Force ◽  
Transmission Electron

Graphene Quantum Dots (GQDs) have been prepared by oxidationhydrothermal reaction, using ball-milling graphite as the starting materials. The prepared GQDs are endowed with excellent luminescence properties, with the optimum emission of 320nm. Blue photoluminescent emitted from the GQDs under ultraviolet light. The GQDs are ~3nm in width and 0.5~2 nm in thickness, revealed by high-resolution transmission electron microscopy and atomic force microscopy. In addition, Fourier transform infrared spectrum evidences the existence of carbonyl and hydroxyl groups, meaning GQDs can be dispersed in water easily and used in cellar imaging, and blue area inside L929 cells were clearly observed under the fluorescence microscope. Both low price of raw material and simple prepared method contribute to the high quality GQDs widespread application in future.

Comprehensive Utilization of Pyrite with High Content of Asrenic

2012 ◽  
Vol 524-527 ◽  
pp. 965-968 ◽  
Author(s):  
Dan Liu ◽  
Shu Ming Wen ◽  
Yong Jun Xian ◽  
Hai Ying Shen ◽  
Shao Jun Bai ◽  
...  
Keyword(s):  
Sulfuric Acid ◽  
Steel Industry ◽  
Raw Material ◽  
High Quality ◽  
Comprehensive Utilization ◽  
Roasting Temperature ◽  
Chinese Steel Industry ◽  
Iron Bearing

A technology of “arsenic removing- sulfuric acid producing- residuals for ironmaking” is proposed for comprehensive utilization of pyrite with high content of arsenic. The effect of roasting temperature and time on arsenic removing was investigated. The arsenic removed residuals obtained under the optimal arsenic removed conditions, was used to be proceeded for sulphur volatilization test. The results demonstrate that final residuals with 63.53% of Fe can be used for steel industry. This technology can be used to fully utilize sulphur and produce high quality concentrate as iron-bearing feed for steel industry, which will help to reduce the pollution of arsenic and extend raw material sourcing for Chinese steel industry.

Understanding the Islamic State—A Review Essay

2016 ◽  
Vol 40 (4) ◽  
pp. 127-165 ◽  
Author(s):  
Daniel Byman
Keyword(s):  
Review Essay ◽  
Military Force ◽  
Islamic State ◽  
The West ◽  
High Quality ◽  
Terrorist Threat ◽  
Security Forces ◽  
Large Numbers ◽  
Raison D’État ◽  
Foreign Fighters

This article reviews several recent books on the Islamic State in order to understand its goals, motivations, strategy, and vulnerabilities. It argues that the Islamic State's ideology is powerful but also highly instrumental, offering the group legitimacy and recruiting appeal. Raison d'etat often dominates its decisionmaking. The Islamic State's strength is largely a consequence of the policies and weaknesses of its state adversaries. In addition, the group has many weaknesses of its own, notably its brutality, reliance on foreign fighters, and investment in a state as well as its tendency to seek out new enemies. The threat the Islamic State poses is most severe at the local and regional levels. The danger of terrorism to the West is real but mitigated by the Islamic State's continued prioritization of the Muslim world and the heightened focus of Western security forces on the terrorist threat. A high-quality military force could easily defeat Islamic State fighters, but there is no desire to deploy large numbers of Western ground troops, and local forces have repeatedly shown many weaknesses. In the end, containing the Islamic State and making modest rollback efforts may be the best local outcomes.

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