SEGURANÇA MARÍTIMA NA REGIÃO DO INDO-PACÍFICO: UMA PERSPECTIVA GEOESTRATÉGICA DO ESTREITO DE MALACCA

Maritime security has been in recent times emerged as a burning issue in the fields of international relations in general and in the Indo-Pacific region in particular. With topographical tectonics, this area includes numerous “choke points” on maritime routes that are strategically important to world trade, playing an important role in the transportation of oil, gas and cargo products from the Middle East to Australia and East Asia. Therefore, maritime security issues for the lifeline of the world economy are concerned by the countries in the Indo-Pacific region, in which the important role of the sea route through Straits of Malacca is increasingly emphasized. With a geostrategic position connecting the Andaman Sea (Indian Ocean) and the South China Sea (Pacific Ocean), Straits of Malacca is the shortest route between the Middle East and Asia in general and Pacific Rim countries in particular. This is the location that accounts for a quarter of the world’s marine traffic annually. Energy security and trade economy of major powerful countries in the Indo-Pacific region depend heavily on the maritime security of Straits of Malacca route. Through an analysis of the Malacca Strait’s geostrategic location, this paper elucidates the Indo-Pacific region’s importance in maritime security field in the first two decades of the twenty-first century.Com uma posição geoestratégica conectando o Mar de Andaman (Oceano Índico) e o Mar da China Meridional (Oceano Pacífico), o Estreito de Malaca é a rota mais curta entre o Oriente Médio e a Ásia em geral e os países do Pacífico em particular. Este é o local que responde por um quarto do tráfego marítimo mundial anualmente. A segurança energética e a economia comercial dos principais países poderosos da região do Indo-Pacífico dependem fortemente da segurança marítima da rota do Estreito de Malaca. Através de uma análise da localização geoestratégica do Estreito de Malaca, este artigo elucida a importância da região do Indo-Pacífico no campo da segurança marítima nas duas primeiras décadas do século XXI

India-China strategic competition in the Indian Ocean

The XXI is considered by major countries in the Asia-Pacific region as ‘the century of sea and ocean' and is accompanied by fierce competition among the nations to gain interest in the sea regions. On the basis that previously only considered the competition for military objectives, geostrategic bases and traffic channels through the straits, nowadays, countries worldwide have stepped up the competition for economic interests and marine resources. The development of military power and the competitive activities for resources at sea show clear the tendency to use the sea to contain the continent. In that context, the Indian Ocean, as the world's third largest ocean, has an important geographic location and rich and diverse natural resources; the arterial sea route is gradually becoming the center of new world geopolitics and an important area in the strategic competition between two 'Asian giants' - India and China. The competition between these countries in the Indian Ocean is growing and profoundly impacts the region's stability and security. This article focuses on the position and important role of the Indian Ocean in the policies of India and China, the fierce competition between the two countries in nearly two decades of the XXI century

The strategic adjustments of China, India, and the US in the Indo-Pacific geopolitical context

Since the beginning of the XXI century, the Indo-Pacific region has become the "focus" of strategic competition between the world's great powers. This area included many "choke points" on sea routes that are strategically important for the development of international trade, playing an important role in transporting oil, gas, and goods around the world from the Middle East to Australia and East Asia. The article analyzed the geostrategic position of the Indo-Pacific region and the strategic adjustments in foreign affairs of some major powers in this region, specifically the US, China, and India. To achieve this goal, the authors used research methods in international relations to analyze the main issues of the study. In addition to reviewing previous scholarly research and reviews, the authors used a comparative approach to assess the interactions between theory and data. The authors believed that these data are important for accurately assessing the strategic importance of the Indo-Pacific region, and this area was an important trigger for the US, China, and India to make adjustments to its foreign policy. If the US proposed a strategy called "Free and Open Indo-Pacific" (FOIP), India's strategy was called the Indo-Pacific Initiative. China's Indo-Pacific strategy was clearly expressed through the "String of Pearls" strategy and the "Belt and Road Initiative" (BRI). As a result, in the geopolitical context of the Indo-Pacific region, the competition between major powers (the US, China, India...) is also becoming fiercer and more complex. It has a significant impact on other countries in the region

US-China rivalry in Southeast Asia region: a study on the South China Sea case

Southeast Asia is one of the places where fierce rivalry is taking place between the two leading powers in the world today - the US and China. The US-China rivalry in this region takes place in key fields, from politics - diplomacy, economy, security - defense to "soft power", the most prominent of which is the South China Sea issue. This article analyzes the strategic importance of the South China Sea in the policy of the US and China, the competition between the US and China in Southeast Asia in general, and the South China Sea in particular. To achieve this goal, the authors use research methods in international relations to analyze the main issues of the study. In addition to reviewing previous scholarly research and reviews, the authors use a comparative approach to assess the interactions between theory and data. The authors believe the data is important for accurately assessing the strategic competition between the US and China in Southeast Asia and the South China Sea. The rise of China in the early years of the XXI century strongly influenced the adjustment of the US policy in Southeast Asia and the powerful US-China rivalry in this region and the South China Sea. This rivalry is becoming increasingly complicated, and geopolitical conflicts between major powers are possible in the following years

A Murnaghan-Nakayama rule for Grothendieck polynomials of Grassmannian type

We consider the Grothendieck polynomials appearing in the K-theory of Grassmannians, which are analogs of Schur polynomials. This paper aims to establish a version of the Murnaghan-Nakayama rule for Grothendieck polynomials of the Grassmannian type. This rule allows us to express the product of a Grothendieck polynomial with a power sum symmetric polynomial into a linear combination of other Grothendieck polynomials.Comment: 10 pages, 7 figure

Near-threshold fatigue propagation of physically through-thickness short and long cracks in a low alloy steel

International audienceIn this paper, the near-threshold fatigue behavior of physically through-thickness short cracks and of long cracks in a low alloy steel is investigated by experiments in ambient air. Physically through-thickness short fatigue cracks are created by gradually removing the plastic wake of long cracks in compact tension specimens. The crack closure is systematically measured using the compliance variation technique with numerical data acquisition and filtering for accurate detection of the stress intensity factor (SIF) at the crack opening. Based on the experimental results, the nominal threshold SIF range is shown to be dependent on the crack length and the characteristic of the crack wake which is strongly dependent on the loading history. The effective threshold SIF range and the relation between the crack propagation rate and the effective SIF range after the crack closure correction are shown to be independent on crack length and loading history. The shielding effect of the crack closure is shown to be related to the wake length and load history. The effective threshold SIF range and the relationship between the crack growth rate and the effective SIF range appear to be unique for this material in ambient air. These properties can be considered as specific fatigue properties of the couple material/ambient air environment

Fatigue Crack Propagation in Gaseous Hydrogen Environment in Low Alloy Steel

International audienceFatigue crack propagation in low alloyed steel (3.5Ni-1.5Cr-0.5Mo-V) used for turbine generator of nuclear plant is studied under 4 bar hydrogen atmosphere in comparison to ambient air and high vacuum. Tests are conducted on CT specimens and the variation of the fatigue crack growth rate da/dN with respect to the amplitude of the applied stress intensity factor ΔK is explored in a wide range and especially in the near threshold domain. The propagation behaviour under hydrogen atmosphere is shown similar to that obtained in air in the low rate range, i.e. when the maximum of the stress intensity factor Kmax is lower than a critical level of 16 MPam1/2 with higher crack growth rate than in high vacuum. This environment effect is related to the presence of residual water vapour in both gases. For Kmax higher than 16 MPam1/2, much faster growth rates under hydrogen atmosphere in comparison to air and vacuum are observed and related to hydrogen assisted intergranular propagation combining fatigue and sustained loading damage. The results are discussed on the basis of micrographic observations supporting the involved mechanisms

Purification and thrombolytic effects in vivo of recombination Nattokinase on carrageenan-induced tail thrombosis in a rat model

Nattokinase is a serine protease with fibrinolytic activity and has been proven clinical efficacy and safety for human use by the oral route. In this study, conducted purified recombinant nattokinase from Bacillus subtillis DB104 strain and thrombolytic effects of nattokinase have been observed in vivo. The result of the enzyme purification by membrane filtration method for enzyme recovery efficiency is 82.45%. Then the enzyme was purified to Q-Sepharose ion exchange chromatography with a purification factor of 1.82 and at a yield of 66.91%. Enzyme activity was 5,457 FU/mg protein. With the carrageenan-induced tail thrombosis in a rat model, results were significantly reduced by 67.3 to 83.6% at oral doses and injected nattokinase compared with the control group at 48 h. At 72 hours the rate increased to 82-89% in the oral dose and up to 91% in the injected dose nattokinase and comparable to 90% for heparin-positive hepatitis

Polyelectrolyte complex micelles by self-assembly of polypeptide-based triblock copolymer for doxorubicin delivery

AbstractPolyelectrolyte complex micelles were prepared by self-assembly of polypeptide-based triblock copolymer as a new drug carrier for cancer chemotherapy. The triblock copolymer, poly(l-aspartic acid)-b-poly(ethylene glycol)-b-poly(l-aspartic acid) (PLD-b-PEG-b-PLD), spontaneously self-assembled with doxorubicin (DOX) via electrostatic interactions to form spherical micelles with a particle size of 60–80 nm (triblock ionomer complexes micelles, TBIC micelles). These micelles exhibited a high loading capacity of 70% (w/w) at a drug/polymer ratio of 0.5 at pH 7.0. They showed pH-responsive release patterns, with higher release at acidic pH than at physiological pH. Furthermore, DOX-loaded TBIC micelles exerted less cytotoxicity than free DOX in the A-549 human lung cancer cell line. Confocal microscopy in A-549 cells indicated that DOX-loaded TBIC micelles were transported into lysosomes via endocytosis. These micelles possessed favorable pharmacokinetic characteristics and showed sustained DOX release in rats. Overall, these findings indicate that PLD-b-PEG-b-PLD polypeptide micelles are a promising approach for anti-cancer drug delivery