Some diophantine quadruples in the ring Z[√-2]

A complex diophantine quadruple with the property D,$(z)$, where $z in$ Z$[sqrt {-2}]$, is a subset of Z$[sqrt {-2}]$ of four elements such that the product of its any two distinct elements increased by $z$ is a perfect square in Z$[sqrt{-2}]$. In the present paper we prove that if $b$ is an odd integer, then there does not exist a diophantine quadruple with the property D$(a + bsqrt{-2})$. For $z=a+bsqrt{-2}$, where $b$ is even, we prove that there exist at least two distinct complex diophantine quadruples if $a$ and $b$ satisfy some congruence conditions

The Impact of Cultural Intelligence of Tourist Guides on Tourist Satisfaction: A Study of Local Tourist Guides in Petra City, Jordan

This paper focuses on investigating the influence of tourist guides' Cultural Intelligence (CI) on their perceived performance and to examine the relationship between this performance and tourists' satisfaction. The study adopted the deductive approach by carrying out a survey using self-administrated questionnaires that were distributed to 382 inbound tourists in Petra city-Jordan, who were selected conveniently. 290 questionnaires were collected with an achieved response rate of 76.1%. Collected data were analyzed using statistical techniques including standard multiple regression and Pearson correlation. Findings showed that CI has a positive effect on local tourist guides' performance, which in turn has a significant positive correlation with the level of tourist satisfaction. Based on these findings, official training programs that include CI courses was recommended for local tourist guides in Petra city

Observation of rogue waves in a 980nm-laser diode subject to filtered optical feedback

International audienceIn this work, rogue waves are observed in a 980 nm laser diode subject to filtered optical feedback via an fibre Bragg grating. A rogue-wave map is established for the first time experimentally as functions of optical feedback ratio and laser current. Rogue waves in our laser system are identified as a part of low frequency fluctuation jump-ups

COMPARATIVE TOXICITY STUDY OF CHLOROQUINE AND HYDROXYCHLOROQUINE ON ADULT ALBINO RATS

Expanded use of Chloroquine and hydroxychloroquine drugs for non-malarial disease entities has resulted in prolonged duration of therapy and higher daily dosages leading to cumulative doses greater than those used in antimalarial therapy. The aim of the study is to evaluate and compare the toxic effects of chloroquine and hydroxychloroquine on different organs of albino rats. The study was conducted on 60 normal albino rats divided into 3 groups, the 1st group is the control group that received only distilled water, the 2nd and the 3rd group were given a single daily oral doses equivalent to 1/10th of LD50 chloroquine and hydroxychloroquine respectively. Assessment of liver and kidney functions, and histopathological changes in liver, kidney, and heart in different groups was done. The chloroquine treated group showed significant elevation of serum glutamic pyruvic transaminase (SGPT), serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase (ALP), total bilirubin (TB), serum creatinine-urea (Cr-U), Creatine Kinase-MB, C-reactive protein and Malonic dialdehyde levels as compared to control and hydroxychloroquine treated group. The histopathological evaluation showed marked hydropic degeneragtion, vascular congestion, interstitial hemorrhage, and necrosis in the liver, kidney and heart of chloroquine treated group, while hydroxychloroquine treated group showed mild congestion and slight cellular degeneration. Thus, hydroxychloroquine is less toxic and physicians should prescribe it better than chloroquine. Chloroquine if prescribed for therapeutic uses should be taken for short periods

COMPARATIVE TOXICITY STUDY OF CHLOROQUINE AND HYDROXYCHLOROQUINE ON ADULT ALBINO RATS

Expanded use of Chloroquine and hydroxychloroquine drugs for non-malarial disease entities has resulted in prolonged duration of therapy and higher daily dosages leading to cumulative doses greater than those used in antimalarial therapy. The aim of the study is to evaluate and compare the toxic effects of chloroquine and hydroxychloroquine on different organs of albino rats. The study was conducted on 60 normal albino rats divided into 3 groups, the 1st group is the control group that received only distilled water, the 2nd and the 3rd group were given a single daily oral doses equivalent to 1/10th of LD50 chloroquine and hydroxychloroquine respectively. Assessment of liver and kidney functions, and histopathological changes in liver, kidney, and heart in different groups was done. The chloroquine treated group showed significant elevation of serum glutamic pyruvic transaminase (SGPT), serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase (ALP), total bilirubin (TB), serum creatinine-urea (Cr-U), Creatine Kinase-MB, C-reactive protein and Malonic dialdehyde levels as compared to control and hydroxychloroquine treated group. The histopathological evaluation showed marked hydropic degeneragtion, vascular congestion, interstitial hemorrhage, and necrosis in the liver, kidney and heart of chloroquine treated group, while hydroxychloroquine treated group showed mild congestion and slight cellular degeneration. Thus, hydroxychloroquine is less toxic and physicians should prescribe it better than chloroquine. Chloroquine if prescribed for therapeutic uses should be taken for short periods

Barium bioaccumulation by bacterial biofilms and implications for Ba cycling and use of Ba proxies

Supplementary Information accompanies this paper at https://doi.org/10.1038/s41467- 018-04069-z.Data availability. The datasets generated during the current study are available from the corresponding author.Ba proxies have been broadly used to reconstruct past oceanic export production. However, the precise mechanisms underlying barite precipitation in undersaturated seawater are not known. The link between bacterial production and particulate Ba in the ocean suggests that bacteria may play a role. Here we show that under experimental conditions marine bacterial biofilms, particularly extracellular polymeric substances (EPS), are capable of bioaccumulating Ba, providing adequate conditions for barite precipitation. An amorphous P-rich phase is formed at the initial stages of Ba bioaccumulation, which evolves into barite crystals. This supports that in high productivity regions where large amounts of organic matter are subjected to bacterial degradation, the abundant EPS would serve to bind the necessary Ba and form nucleation sites leading to barite precipitation. This also provides new insights into barite precipitation and opens an exciting field to explore the role of EPS in mineral precipitation in the ocean.This study was supported by the European Regional Development Fund (ERDF) cofinanced grant CGL2015-66830-R (MINECO Secretaría de Estado de Investigación, Desarrollo e Innovación, Spain), Research Groups BIO 103 and RNM-179 (Junta de Andalucía), and the University of Granada (Unidad Científica de Excelencia UCEPP2016-05)

Optimal Design of Thermal Membrane Distillation Systems for the Treatment of Shale Gas Flowback Water

Shale gas production is associated with the significant consumption of fresh water and discharge of wastewater. The flowback wastewater is tied to the hydraulic fracturing technology used for completing and stimulating the horizontal wells in the very tight formations characterizing the shale formation. Treatment and reuse of these large volumes of wastewater can lead to substantial savings in fresh water usage and reduction of the negative environmental impact thereby enhancing sustainability of the shale gas industry. Such treatment requires selective and cost-effective technology.Thermal membrane distillation (TMD) is an emerging technology that offers several advatanges such as high selectivity in separating water from inorganic solutes and modular nature that can accommodate a wide range of flows. It can also utilize low-level heats that are typically available from shale-gas production and processing.The objective of this work is to develop an optimization approach for the design of TMD systems to treat flowback water. A multi-period formulation is developed to account for the time-based variation in the flowrate and concentration of the flowback water. Modeling equations are used to relate design and operating variables to performance and cost. The optimization formulation also accounts for the period-based changes in the required design and operating variables and reconciles them over the selected periods. Other constraints include quality of the permeate and water-recovery ratio. The optimization formulation and design approach are applied to a case study for the treatment of flowback water for the Marcellus Shale Play. For 75% water recovery, the cost of the permeate is about $2.6/m3. As higher recoveries are sought, the cost per m3 of permeate increases due to capital productivity factors in dealing with the decreasing amount of flowback water over time. The results are reported using a Pareto chart that trades off recovery objectives with cost of treated water

Using Artificial Intelligence for Optimizing Natural Frequency of Recycled Concrete for Mechanical Machine Foundation

This paper investigates the mechanical properties of two different types of recycled concrete, which use wood and rubber, relative to those characteristics of pure concrete, in terms of maximum load and natural frequencies. This paper contributes to the state of the art in this area in a number of ways. Firstly, the paper provides furtherance to the progressively growing literature in the field of recycled concrete and mechanical properties of materials. Secondly, the paper investigates the mechanical properties of two different types of recycled concrete by means of investigating the natural frequency of the samples, which is a new contribution. Lastly, the results from predicting the natural frequencies of concrete using fuzzy logic have been effectively assessed and compared with the analytical results. Results from the study show that the pure concrete samples produced maximum natural frequency, then concrete samples with wood, and lastly, concrete samples with rubber. The tolerance between the lab test results and fuzzy logic is approximately 5%. These results could have significant implications for furthering recycled concrete research and for designing machine foundations. Evidence of the applicability of fuzzy logic as a predictive and analysis tool for the mechanical properties of recycled concrete are discussed

Upconversion nanoparticles as intracellular pH messengers

Abstract: Upconversion nanoparticles (UCNPs) should be particularly well suited for measurement inside cells because they can be imaged down to submicrometer dimensions in near real time using fluorescence microscopy, and they overcome problems, such as photobleaching, autofluorescence, and deep tissue penetration, that are commonly encountered in cellular imaging applications. In this study, the performance of an UCNP modified with a pH-sensitive dye (pHAb) is studied. The dye (emission wavelength 580 nm) was attached in a polyethylene imine (PEI) coating on the UCNP and excited via the 540-nm UCNP emission under 980-nm excitation. The UC resonance energy transfer efficiencies at different pHs ranged from 25 to 30% and a Förster distance of 2.56 nm was predicted from these results. Human neuroblastoma SH-SY5Y cells, equilibrated with nigericin H+/K+ ionophore to equalize the intra- and extracellular pH‚ showed uptake of the UCNP-pHAb conjugate particles and, taking the ratio of the intensity collected from the pHAb emission channel (565–630 nm) to that from the UCNP red emission channel (640–680 nm), produced a sigmoidal pH response curve with an apparent pKa for the UCNP-pHAb of ~ 5.1. The UCNP-pHAb were shown to colocalize with LysoBrite dye, a lysosome marker. Drug inhibitors such as chlorpromazine (CPZ) and nystatin (NYS) that interfere with clathrin-mediated endocytosis and caveolae-mediated endocytosis, respectively, were investigated to elucidate the mechanism of nanoparticle uptake into the cell. This preliminary study suggests that pH indicator–modified UCNPs such as UCNP-pHAb can report pH in SH-SY5Y cells and that the incorporation of the nanoparticles into the cell occurs via clathrin-mediated endocytosis. Graphical abstrac