A computational study of order-disorder phenomena in Mg2TiO4 spinel (qandilite)

We have used a combination of classical and quantum-mechanical atomistic calculations, together with Monte Carlo simulations, to study order-disorder phenomena in the spinel mineral qandilite, Mg2TiO4. Using an interatomic potential model akin to those previously used for 2-3 spinels yielded a general increase in energy E as a function of inversion parameter x, and thus incorrectly predicted a normal-spinel ground state, whereas the E(x) behavior as modeled by density-functional theory exhibited a maximum at an intermediate degree of inversion and correctly predicted an inverse-spinel ground state. We therefore used the quantum-mechanical simulations to derive pair interaction parameters (for nearest-neighbor tetrahedral-tetrahedral, octahedral-octahedral, and tetrahedral-octahedral interactions) and chemical potential to use in Monte Carlo simulations of order-disorder in qandilite. The simulated cation distributions compared favorably with those obtained experimentally, although the long-range ordering transition to the tetragonal P4122 phase was not observed when using only nearest-neighbor interactions. However, this transition could be observed following the addition of two extra parameters to the model. The simulations were used to calculate the effect of short- and long-range cation order on the configurational entropy of qandilite as a function of temperature. The calculated entropy of the high-temperature cubic phase was in very good agreement with the experimental value recently determined, supporting the suggestion that there is considerable short-range order in qandilite

Fatigue life under non-Gaussian random loading from various models

Fatigue test results on the 10HNAP steel under constant amplitude and random loading with non-Gaussian probability distribution function, zero mean value and wide-band frequency spectrum have been used to compare the life time estimation of the models proposed by Bannantine, Fatemi–Socie, Socie, Wang–Brown, Morel and Łagoda–Macha. Except the Morel proposal which accumulates damage step by step with a proper ethodology, all the other models use a cycle counting method. The rainflow algorithm is used to extract cycles from random histories of damage parameters in time domain. In the last model, where a strain energy density parameter is employed, additionally spectral method is evaluated for fatigue life calculation in the frequency domain. The best and very similar results of fatigue life assessment have been obtained using the models proposed by Socie and by Łagoda–Macha, both in time and frequency domains for the last one.With the support of the Commission of the European Communities under the FP5, GROWTH Programme, contract No. G1MA-CT-2002-04058 (CESTI)

On the rehydration of organic layered double hydroxides to form low-ordered carbon/LDH nanocomposites

Low-ordered carbon/layered double hydroxide (LDH) nanocomposites were prepared by rehydration of the oxides produced by calcination of an organic LDH. While the memory effect is a widely recognized effect on oxides produced by inorganic LDH, it is unprecedented from the calcination/rehydration of organic ones. Different temperatures (400, 600, and 1100 °C) were tested on the basis of thermogravimetric data. Water, instead of a carbonate solution, was used for the rehydration, with CO2 available from water itself and/or air to induce a slower process with an easier and better intercalation of the carbonaceous species. The samples were characterized by X-ray powder diffraction (XRPD), infrared in reflection mode (IR), and Raman spectroscopies and scanning electron microscopy (SEM). XRPD indicated the presence of carbonate LDH, and of residuals of unreacted oxides. IR confirmed that the prevailing anion is carbonate, coming from the water used for the rehydration and/or air. Raman data indicated the presence of low-ordered carbonaceous species moieties and SEM and XRPD the absence of separated bulky graphitic sheets, suggesting an intimate mixing of the low ordered carbonaceous phase with reconstructed LDH. Organic LDH gave better memory effect after calcination at 400 °C. Conversely, the carbonaceous species are observed after rehydration of the sample calcined at 600 °C with a reduced memory effect, demonstrating the interference of the carbonaceous phase with LDH reconstruction and the bonding with LDH layers to form a low-ordered carbon/LDH nanocomposite

Minimally invasive management of vital teeth requiring root canal therapy

The present study aimed to investigate the possible use of a non-instrumentation technique including blue light irradiation for root canal cleaning. Extracted human single rooted teeth were selected. Nine different groups included distilled water, NaOCl, intra-canal heated NaOCl, and NaOCl + EDTA irrigation after either instrumentation or non-instrumentation, and a laser application group following non-instrumentation technique. The chemical assessment of the root canal dentine was evaluated using EDS and FT-IR. Surface microstructural analyses were performed by using SEM. The antimicrobial efficacy of different preparation techniques was evaluated using microbial tests. Laser application didn’t change the Ca/P, carbonate/phosphate and amide I/phosphate ratios of the root canal dentin the root canal dentin preserved its original form after light application. The instrumentation decreased the carbonate/phosphate and amide I/phosphate ratios of the root canal dentin regardless of the irrigation solution or technique (p < 0.05). According to the microbiological tests, the light application could not provide antibacterial efficacy as much as NaOCl irrigation. The NaOCl irrigation both in the non-instrumentation and instrumentation groups significantly reduced the number of bacteria (p < 0,05). Minimally invasive root canal preparation techniques where the root canal is not instrumented and is disinfected by laser irradiation followed by obturation with a hydraulic cement sealer may be an attractive treatment option for management of vital teeth needing root canal therapy and does not have any detrimental effects on the chemical structure of dentin

ANALISA KAPASITAS DAN TINGKAT PELAYANAN PADA RUAS JALAN WOLTER MONGINSIDI KOTA MANADO

Melihat kondisi kota Manado saat ini, jika ditinjau dari segi sarana dan prasarana transportasi sudah mulai berbanding terbalik. Dimana kebutuhan akan jalan tidak sebanding dengan banyaknya jumlah kendaraan yang ada. Sehingga hal ini akan menimbulkan dampak negatif terhadap pergerakan lalu-lintas, misalnya terjadi peningkatan volume lalu-lintas pada ruas-ruas jalan tertentu yang mengakibatkan terjadinya kemacetan panjang terutama pada jam-jam sibuk. Akibatnya, jarak yang sebenarnya singkat akan ditempuh dalam waktu yang cukup lama.Studi yang dilakukan pada penelitian ini bersifat riset yang dilakukan pada ruas jalan Wolter Monginsidi kota Manado dengan tujuan untuk menghitung kapasitas dan tingkat pelayanan, yaitu dengan cara melakukan survey selama 4 hari (dimulai dari jam 7.00 pagi sampai dengan jam 19.00 malam) yang mana dari survey ini didapatkan data volume lalu-lintas, kecepatan kendaraan serta data geometrik jalan. Dalam pengolahan data dilakukan dengan metode Manual Kapasitas Jalan Indonesia (MKJI) 1997 dimana derajat kejenuhan (DS) sebagai indikator perilaku lalu-lintas pada ruas jalan Wolter Monginsidi Kota Manado.Dari hasil pengolahan data survey didapatkan nilai kapasitas pada ruas jalan ini yaitu sebesar 2934.36 smp/jam dan tingkat pelayan pada LOS E yang artinya bahwa volume lalu-lintas pada ruas jalan Wolter Monginsidi Kota Manado saat ini mendekati/berada pada kapasitas arus tidak stabil, kecepatan kendaraan terkadang terhenti. Kata kunci : analisa kapasitas, kecepatan, tingkat pelayana

Genome Biol.

With genome analysis expanding from the study of genes to the study of gene regulation, 'regulatory genomics' utilizes sequence information, evolution and functional genomics measurements to unravel how regulatory information is encoded in the genome

Elastomer and resin replicas for sem observation of metallic materials

The replica technique is often used to study damage evolution at the surface of specimens or industrial components and understand the physicial phenomena responsible for fatigue crack initiation before failure. Replicas are usually made from acetate cellulose film. This paper presents an alternative technique generally used by archaeologists to study lithic use-wear and bone modification. A mold is made from a dental elastomer (silicon based impression material) and a positive replica is made by casting epoxy resin in the mold. Comparative SEM analysis of damaged metallic specimens and their resin replicas show that this technique provides a good resolution and preserves details up to 0.5 micrometer. This easy and low cost method allows a systematic study of micro-crack growth

Exploiting bluetooth vulnerabilities in e-health IoT devices

Internet of Things (IoT) is an interconnected network of heterogeneous things through the Internet. The current and next generation of e-health systems are dependent on IoT devices such as wireless medical sensors. One of the most important applications of IoT devices in the medical field is the usage of these smart devices for emergency healthcare. In the current interconnected world, Bluetooth Technology plays a vital role in communication due to its less resource consumption which suits the IoT architecture and design. However Bluetooth technology does not come without security flaws. In this article, we explore various security threats in Bluetooth communication for e-Health systems and present some examples of the attacks that have been performed on e-Health systems by exploiting the identified vulnerabilities - 2019 Association for Computing Machinery.This publication was made possible by NPRP grant NPRP10-0125-170250 from the Qatar National Research Fund (a member of Qatar Foundation). The statements made herein are solely the responsibility of the authors.Scopu