Pengaruh PH, Kecepatan Putar dan Asam Asetat terhadap Karakteristik CO2 Corrosion Baja ASME SA516 Grade 70

Fenomena korosi merupakan sesuatu yang pasti terjadi pada setiap logam. Laju korosi dari suatu material dipengaruhi oleh beberapa faktor diantaranya yaitu nilai pH lingkungan dan karakteristik aliran fluida yang kontak langsung dengan logam. Pada oil and gas industry, baja ASME SA 516 grade 70 sering digunakan sebagai material flowline dan banyak terjadi CO2 Corrosion. Penelitian ini bertujuan untuk melakukan studi laju korosi material baja ASME SA 516 grade 70 yang mengandung CO2. Penelitian dilakukan dengan metoda weight loss menggunakan alat Rotating Cylinder Electrode (RCE) selama 10 hari dan metode Polarization selama 1 jam. Selain itu digunakan pula XRD dan SEM guna mendukung data-data analisa. Pada penelitian ini digunakan media elektrolit NaCl 3,5% dengan kandungan CH3COOH sebesar 0 ppm dan 1500 ppm dengan variasi kecepatan putaran yaitu 0 RPM, 150 RPM, 300 RPM, dan 450 RPM pada pH 5 dan 6. Pada pengujian polarization, didapatkan hasil laju korosi tertinggi sebesar 9.9323 mm/y pada larutan CH3COOH 1500 ppm pH 5 dan kecepatan putar 450 RPM, sedangkan data dari pengujian weight loss sebesar 4.8795 mm/y. Hasil pengamatan SEM menunjukkan adanya perbedaan morfologi pada permukaan spesimen karena pengaruh kecepatan putaran. Kecepatan putaran mengakibatkan tergerusnya produk korosi oleh aliran. Pada pengujian XRD dengan menggunakan spesimen pH 5 dengan kandungan 0 ppm dan 1500 ppm 0 RPM ditemukan FeCO3, Fe(OH)3 dan senyawa FeOOH sebagai produk korosi

A vacuum-air permeability test for in-situ assessment of cover concrete

The transport properties of fluids in the cover layer are the main indicator of the durability of reinforced concrete structures. Many laboratory tests exist for measuring these properties. However, there are relatively few tests that can be used on site. In this paper, the development of a new nondestructive rapid test capable of measuring the air permeability of in situ concrete is described. The new method measures the movement of gas between different holes drilled into the concrete and gives results for the permeability of the concrete and for the volume of concrete that has been tested. A pressure measuring method was developed to measure the pressure inside the concrete by using a piezoresistive pressure transducer and a data logger. Four different techniques were investigated and one preparation technique is recommended for in situ use

Effects of sublattice symmetry and frustration on ionic transport in garnet solid electrolytes

We use rigorous group-theoretic techniques and molecular dynamics to investigate the connection between structural symmetry and ionic conductivity in the garnet family of solid Li-ion electrolytes. We identify new ordered phases and order-disorder phase transitions that are relevant for conductivity optimization. Ionic transport in this materials family is controlled by the frustration of the Li sublattice caused by incommensurability with the host structure at non-integer Li concentrations, while ordered phases explain regions of sharply lower conductivity. Disorder is therefore predicted to be optimal for ionic transport in this and other conductor families with strong Li interaction.Comment: 6 pages, 4 figures, and supplementary informatio

Back to the future : the Arab uprisings and state (re)formation in the Arab world

This article contributes to debates that aim to go beyond the “democratization” and “post-democratization” paradigms to understand change and continuity in Arab politics. In tune with calls to focus on the actualities of political dynamics, the article shows that the literatures on State Formation and Contentious Politics provide useful theoretical tools to understand change/continuity in Arab politics. It does so by examining the impact of the latest Arab uprisings on state formation trajectories in Iraq and Syria. The uprisings have aggravated a process of regime erosion – which originated in post-colonial state-building attempts – by mobilizing sectarian and ethnic identities and exposing the counties to geo-political rivalries and intervention, giving rise to trans-border movements, such as ISIS. The resulting state fragmentation has obstructed democratic transition in Syria and constrained its consolidation in Iraq.PostprintPeer reviewe

Hormonal control of gubernaculum development during testis descent: gubernaculum outgrowth in vitro requires both insulin-like factor and androgen

The gubernaculum connects the gonad to the inguinoscrotal region and is involved in testis descent. It rapidly develops in the male fetus, whereas development in the female fetus is lacking. Possible factors involved in gubernaculum development are androgens, anti-Mullerian hormone (AMH), and insulin-like factor (Insl3). Sexual dimorphism in gubernaculum development correlated with the mitotic activity of cells in the gubernacular bulbs from male and female fetuses. Androgen receptor expression was restricted to the mesenchymal core of the gubernacular bulb, whereas skeletal muscle was detected in its outer layer. In an organ culture system devised to further study gubernaculum development in vitro, morphology of gubernacular explants grown in the presence of testes was comparable with that of gubernacula developed in vivo. Testicular tissue or medium containing R1881, a synthetic androgen, had a growth stimulatory effect on gubernacular explants compared with ovarian tissue or basal medium only. Moreover, Amh-/-, Amh+/-, and Insl3+/- testes stimulated the growth of gubernacular explants to the same extent as control testes. Insl3-/- testes, however, did not produce such an activity. This study reveals an essential role for both androgen and Insl3 in the gubernaculum outgrowth during transabdominal testis descent

Profile of Nasopharyngeal Carcinoma in Dr. Cipto Mangunkusumo National Hospital, 2010

Nasopharyngeal carcinoma (NPC) is the most common head and neck Malignancy in Indonesia. NPCpresents numerous challenges from non-specific signs and symptoms until lack of awareness from generalpractitioners (GP), which lead to late or missed diagnosis. Early diagnosis and prevention are proposedas the best solutions for this problem. In order to do that, we need a complete and well-managed patients’data. This study aims to reveal the demographic, clinical and histopathologic characteristics of NPC inIndonesia. A cross-sectional study was conducted by collecting medical records of all NPC patients in 2010from Otorhinolaryngology Department of Dr. Cipto Mangunkusumo National Hospital. The extracted datawere then analyzed to describe the problem of NPC in Indonesia. Out of 167 patients, 68.3% of the patientsare male and most of them are Sundanese and Javanese. Palpable lump in the neck is the most commoncomplaint in presentation (58.1%), followed by nasal congestion (49.1%). Salted fish consumption was themost prevalent risk factor (29.9%). Based on the histopathologic findings, 75.4% of the cases were classifiedas WHO-3 and around half of the patients (51%) were in stage IV upon diagnosis. Studying demographic andclinical characteristics of NPC patients is the first step to overcome problems caused by NPC in Indonesia

Influence of Silica Fume, Fly Ash, Super Pozz, and High Slag Cement on Water Permeability and Strength of Concrete

In this study, effects of mineral admixtures on the water permeability and compressive strength of concretes containing silica fume (SF) and fly ash (FA), super pozz (SP) were experimentally investigated. Permeability of concrete was determined through DIN 1048 (Part 5). The research variables included cement type, ordinary Portland cement (OPC) or high slag cement (HSC), and mineral admixtures content were used as a partial cement replacement. They were incorporated into concrete at the levels of 5%, 10%, and15% for silica fume and 10%, 20%, 30% for fly ash, or super pozz by weight of cement. Water- cement ratio of 0.40 was used and tests were carried out at 28 days. From the tests, the lowest measured water permeability was for the 10% super pozz and 10% silica fume or 20% fly ash mixes. Although the highest compressive strengths of concretes determined was 10% silica fume mix for ordinary Portland cement and were reduced as the increase in the replacement ratios for other mineral admixtures than ordinary Portland cement concrete.The main objective of this research was to study the water permeability and compressive strength of concrete containing silica fume, fly ash, and super pozz and high slag cement to achieve the best concrete mixture have lowest permeability. The results were compared to the control concrete ordinary Portland cement concrete without admixtures. The optimum cement replacement by FA, SP and SF in this experiment is 10% SP. The knowledge on the strength and permeability of concrete containing silica fume and fly ash, super pozz and high slag cement could be beneficial on the utilization of these waste materials in concrete work, especially on the topic of durability

Outcomes and risk score for distal pancreatectomy with celiac axis resection (DP-CAR) : an international multicenter analysis

Background: Distal pancreatectomy with celiac axis resection (DP-CAR) is a treatment option for selected patients with pancreatic cancer involving the celiac axis. A recent multicenter European study reported a 90-day mortality rate of 16%, highlighting the importance of patient selection. The authors constructed a risk score to predict 90-day mortality and assessed oncologic outcomes. Methods: This multicenter retrospective cohort study investigated patients undergoing DP-CAR at 20 European centers from 12 countries (model design 2000-2016) and three very-high-volume international centers in the United States and Japan (model validation 2004-2017). The area under receiver operator curve (AUC) and calibration plots were used for validation of the 90-day mortality risk model. Secondary outcomes included resection margin status, adjuvant therapy, and survival. Results: For 191 DP-CAR patients, the 90-day mortality rate was 5.5% (95 confidence interval [CI], 2.2-11%) at 5 high-volume (1 DP-CAR/year) and 18% (95 CI, 9-30%) at 18 low-volume DP-CAR centers (P=0.015). A risk score with age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) score, multivisceral resection, open versus minimally invasive surgery, and low- versus high-volume center performed well in both the design and validation cohorts (AUC, 0.79 vs 0.74; P=0.642). For 174 patients with pancreatic ductal adenocarcinoma, the R0 resection rate was 60%, neoadjuvant and adjuvant therapies were applied for respectively 69% and 67% of the patients, and the median overall survival period was 19months (95 CI, 15-25months). Conclusions: When performed for selected patients at high-volume centers, DP-CAR is associated with acceptable 90-day mortality and overall survival. The authors propose a 90-day mortality risk score to improve patient selection and outcomes, with DP-CAR volume as the dominant predictor