Magnetic excitations in quantum rare earth pyrochlores

Rare-earth pyrochlores are materials with chemical formula A₂B₂O₇, where A is the rare-earth ion and B is a transition metal. At low temperature, these systems host various magnetic states such as spin ice, spin liquid state, ferromagnetic ordering, all in-all out, and anti-ferromagnetic ordering. For each rare-earth ion with total angular momentum J, the 2J + 1 fold degeneracy splits into singlets and doublets due to the crystal electric field. However, the crystal electric field ground state for most of the magnetic ions is a doublet that comes into three different varieties, labeled as ┌₃, ┌₄, ┌₅,₆. This work focuses only on systems in which the ground state doublet is well-separated from the first excited state so that we end up with effective two=state systems, referred to as quantum rare-earth pyrochlores. The low temperature excitations of interacting spins have a wave nature and are referred to as spin waves or magnons, where the energy of these waves is quantized. To study these magnons, we apply the Holstein-Primakoff transformation on the effective spin Hamiltonian to construct a bosonic Hamiltonian that describes magnons. In this study, we limit ourselves to the linear spin-wave approximation in which we diagonalize the magnonic Hamiltonian analytically and numerically for various systems of interest. In particular, we study magnons in Nd₂Zr₂O₇ which orders in an all in-all out state near 0.285 K, in Er₂Ti₂O₇ with a antiferromagnetic state below 1.2 K, and finally the Yb₂Ti₂O₇ which orders ferromagnetically near 0.2 K

Response of Sweet Pepper Capsicum Annulus L. (Qurtuba Cultivar) To Spraying With Two Types of Potassium Fertilizer Cultivated In Plastic House

نفذت تجربة حقلية في البيت البلاستيكي غير المدفأ في الكلية التقنية المسيب للموسم الخريفي 2016 لدراسة مدى استجابة نبات الفلفل الحلو Capsicum annuum L. صنف قرطبة للرش الورقي بنوعين من الاسمدة البوتاسية الورقية التجارية في تربة رملية مزيجة لدراسة تأثير اربعة مستويات من سماد البوتاسيوم والعناصر الصغرى (صفر، 4، 6، 8 مل.لتر-1) واربعة مستويات من سماد البوتاسيوم والكبريت KTS (صفر، 2، 4، 6 مل.لتر-1) وتداخلهما على بعض مؤشرات النمو الخضري والزهري والحاصل ونوعيته، صممت التجربة وفق تصميم القطاعات تامة التعشية RCBD  وقورنت المتوسطات باختبار اقل فرق معنوي LSD وبمستوى معنوية 5%. اشارت النتائج الى تفوق معاملة الرش بسماد البوتاسيوم والعناصر الصغرى بمستوى (8 مل.لتر-1) معنويا في زيادة متوسطات طول النبات وعدد الافرع المثمرة والمساحة الورقية للنبات والوزن الجاف للمجموع الخضري وعدد الازهار في النبات ونسبة العقد ومحتوى الاوراق من الكلوروفيل والنتروجين والفسفور والبوتاسيوم وعدد الثمار ووزن الثمرة والحاصل المبكر والكلي ومحتوى فيتامين C ونسبة المواد الصلبة الذائبة الكلية وبنسب زيادة بلغت 19.47، 29.54، 16.68، 30.01، 11.26، 24.09، 38.16، 24.36، 16.67، 34.00، 21.87، 20.27، 50.46، 45.96، 39.33، و70.85% بالتتابع قياسا بمعاملة المقارنة، وهو نفس سلوك معاملة الرش بسماد البوتاسيوم والكبريت اذ تفوقت المعاملة (4  مل.لتر-1) في جميع الصفات اعلاه اذ بلغت نسب الزيادة 31.72، 53.53، 49.88، 15.82، 14.84، 24.54، 19.79، 36.73، 21.05، 47.55، 24.53، 19.07، 49.43، 48.01، 30.29 و36.56% بالتتابع قياسا بمعاملة المقارنة. اما معاملات التداخل فقد اظهرت تفوق معاملة الرش بخليط من (8 مل. لتر-1 + 4 مل. لتر-1) واعطائها اعلى القيم لجميع الصفات اعلاه وبلغت 109.5 سم، 6.4 فرع، 25.3 دسم2، 132.7 غم، 62.7 زهرة، 43.9%، 65.11 spad، 2.22%، 0.75%، 2.55%، 34.6 ثمرة، 108.3 غم، 0.790 كغم. نبات-1، 3.747 كغم. نبات-1، 69.2 ملغم.100مل-1، و10.4% بالتتابع.Field experiment was conducted in the non-heated plastic house at Al-Mussaib Technical College in the autumn season 2016 to study the Response of sweet pepper Capsicum annuum L. (Qurtuba cultivar) to foliar spraying with two types of foliar commercial Potassium fertilizers in loamy sand soil. To study the effect of four levels of potassium fertilizer and micronutrients (0, 4, 6, 8 ml.L-1), four levels of potassium fertilizer and Sulfur KTS (0, 2, 4, 6 ml.L-1) and their interaction on some vegetative and flowering growth indicators, yield and its components. The experiment was designed according to the Randomized Complete Block Design (RCBD) and the averages were compared with the least significant difference (LSD), with a significant level of 5%. The result indicated to the excelling of the spraying treatment with potassium and micronutrient (8 ml.L-1) by giving it a significant level in increasing the averages of plant height, number of branches, leaf area, dry weight for total  vegetative, number of flowers in plant, percentage of fruit set, the leaves content of (chlorophyll, nitrogen, Phosphorus and potassium), early and total yield, the content of vitamin C, and percentage of Total Soluble Solids, with an increasing percentage of (19.47, 29.54, 16.68, 30.01, 11.26, 24.09, 38.16, 24.36, 16.67, 34.00, 21.87, 20.27, 50.46, 45.96, 39.33, 70.85%), respectively, compared to control treatment.  Which is the same behavior as spraying treatment with potassium fertilizer and sulfur, where treatment (4 ml.L-1) was excelled in all the above traits, where the percentages of increasing were (31.72, 53.53, 49.88, 15.82, 14.84, 24.54, 19.79, 36.73, 21.05, 47.55, 24.53, 19.07, 49.43, 48.01, 30.29, 36.56%), respectively, compared to the control treatment. As for interaction treatments, it has showed excelling the spraying treatment with a mixture of (8 ml. L-1 + 4 ml. L-1) by giving it the highest values for all the above traits amounted of (109.5 cm, 6.4 branches, 25.3 dm2, 132.7 g, 62.7 flower, 43.9% 2.22%, 0.75%, 2.55%, 34.6 fruits, 108.3 g, 0.790 kg. plant-1, 3.747 kg. plant-1, 69.2 mg.100 ml-1, 10.4%), respectively

Photocatalytic degradation efficiency of azo dye in aqueous phase using different photo catalysts

The new azo dye [4-(4-hydroxy-2-methylnaphthyl)diazenyl]benzoic acid was synthesized by the reaction of 2-methyl-1-naphthol with p-amino benzoic acid. The photcatalytic degradation of azo dye has been investigated by using zinc oxide and cadmium sulfide. This degradation was carried out by the irradiation of aqueous suspended solutions containing different concentrations of this dye using 0.11 g/100 mL of metal oxide (semiconductors) ZnO and CdS. A mercury lamp 125 W in a Pyrex photoreaction cell of 100 mL at room temperature was used as an irradiation source. The effect of the catalyst on the photocatalytic degradation of the prepared dye was studied via several experiments at different conditions, where they involve the effect of the catalyst mass and the effect of the dye concentrations. The irradiated solutions were studied using UV-Vis spectrophotometer. It has been the performance of photocatalytic system that using ZnO was observed to be better than cadmium sulfide system for degrade the azo compound from its aqueous solution.                     KEY WORDS: Photocatalytic, Degradation, Semiconductors, Zinc oxide; Cadmium sulphide, Azo dye   Bull. Chem. Soc. Ethiop. 2020, 34(3), 463-469. DOI: https://dx.doi.org/10.4314/bcse.v34i3.

EFFECT OF AUTOLOGOUS PLATELET-RICH PLASMA ON DISTRACTION OSTEOGENESIS IN THE MANDIBLE OF RABBITS: A MORPHOLOGIC AND MORPHOMETRIC APPROACH

Distraction osteogenesis of the jaws is a common surgical practice in the treatment of pediatric craniofacial deformities. Autologous platelet rich plasma (PRP) has been used to increase the healing potential of bones in humans during distraction osteogenesis. This article aims to study the morphometric and morphologic parameters resulting from the effect of PRP on bone healing after mandibular distraction in rabbits. Right mandibular distraction was performed in 12 rabbits divided equally into 2 groups. PRP and physiological saline were injected, according to a defined protocol, in the callus following distraction of the experimental and control groups respectively. The rabbits were sacrificed after a consolidation period of 45 days and the mandibles were surgically removed. Bone mineral density, radiographic analysis, mechanical properties and histological features of the lengthened bones were assessed using radiographic examination, dual X-ray absorptiometry, biomechanical testing and histology. Results showed that the regenerate bone density, the amount of trabeculation in addition to the bone mineral density and mineral content, as measured by absorptiometry, were better with PRP but not significantly different between groups. Two radiographs revealed a more consistent healing in the experimental mandibles compared with erratic outcomes in corresponding controls. Two of the latter could not be subjected to any mechanical testing because the mandibular parts, connected with fibrous tissue, were separated. Consequently, the biomechanical test depicted greater maximal loads in the experimental group. The histological studies exhibited more ossification and less connective tissue fibers in the experimental group. PRP accelerated healing of mandibles in rabbits following distraction and improved their biomechanical properties. These findings have significant clinical implications on reducing the period of consolidation of the mandibles which may not be immobilized like other bones for long period tim

Inland valley rice production systems and malaria infection and disease in the forest region of western Côte d'Ivoire

Background: This study aimed to determine the epidemiological impact of rice cultivation in inland valleys on malaria in the forest region of western Côte d'Ivoire. The importance of malaria was compared in terms of prevalence and parasite density of infections and also in terms of clinical malaria incidence between three agro-ecosystems: (i) uncultivated inland valleys, (R0), (ii) inland valleys with one annual rice cultivation in the rainy season, (R1) and (iii) developed inland valleys with two annual rice cultivation cycles, (R2). Methods: Between May 1998 and March 1999, seven villages of each agro-ecosystem (R0, R1 and R2) were randomly selected among villages pooled by farming system. In these 21 villages, a total of 1,900 people of all age groups were randomly selected and clinically monitored during one year. Clinical and parasitological information was obtained by active case detection of malaria episodes carried out during eight periods of five consecutive days scheduled at six weekly intervals and by cross-sectional surveys. Results: Plasmodium falciparum was the principal parasite observed in the three agro-ecosystems. A level of holoendemicity of malaria was observed in the three agro-ecosystems with more than 75% of children less than 12 months old infected. Geometric mean parasite density in asymptomatic persons varied between 180 and 206 P. falciparum asexual forms per μL of blood and was associated with season and with age, but not with farming system. The mean annual malaria incidence rate reached 0.7 (95% IC 0.5-0.9) malaria episodes per person in R0, 0.7 (95% IC 0.6-0.9) in R1 and 0.6 (95% IC 0.5-0.7) in R2. The burden of malaria was the highest among children under two years of age, with at least four attacks by person-year. Then malaria incidence decreased by half in the two to four-year age group. From the age of five years, the incidence was lower than one attack by person-year. Malaria incidence varied with season with more cases in the rainy season than in the dry season but not with farming system. Conclusion: In the forest area of western Côte d'Ivoire, inland valley rice cultivation was not significantly associated with malaria burden

A model reference-based adaptive PSS4B stabilizer for the multi-machines power system

Two-inputs adaptive IEEE multi-bands power system stabilizer (PSS4B) was developed for oscillations damping control in power systems. Two supplementary loops based on model reference (MR) adaptive control were added to the typical PSS4B design. The MR has the same loops’ parameters of the typical PSS4B, and hence, avoiding a complex tuning process. The proposed PSS has a self-tuning gain reduction block to avoid any negative impact due to the high gains value during the disturbance time. The proposed PSS was applied on the four-machine benchmark power system. To evaluate the robustness of the proposed PSS, it was tested in comparison with the Delta W PSS, one-input multi-bands PSS4B (1iMB) and two-inputs multi-bands PSS4B (2iMB) stabilizers. The integration of the proposed PSS was demonstrating using different study cases. These cases consider the small-signal stability (SSS), large-signal stability (LSS) and the coordination test for the local and inter-area excited power modes. The proposed PSS demonstrated robust and superior responses in all cases

RUNX1/ETO blocks selectin-mediated adhesion via epigenetic silencing of PSGL-1

RUNX1/ETO (RE),the t(8;21)-derived leukemic transcription factor associated with acute myeloid leukemia (AML) development, deregulates genes involved in differentiation, self-renewal and proliferation. In addition, these cells show differences in cellular adhesion behavior whose molecular basis is not well understood. Here, we demonstrate that RE epigenetically silences the gene encoding P-Selectin Glycoprotein Ligand-1 (PSGL-1) and downregulates PSGL-1 expression in human CD34+ and murine lin-hematopoietic progenitor cells. Levels of PSGL-1 inversely and dose-dependently correlate with RE oncogene levels. However, a DNA-binding defective mutant fails to downregulate PSGL-1. We show by ChIP experiments that the PSGL-1 promoter is a direct target of RE and binding is accompanied by high levels of the repressive chromatin mark histone H3K27me3. In t(8;21)+ Kasumi-1 cells, PSGL-1 expression is completely restored at both the mRNA and cell surface protein levels following RE downregulation with short hairpin RNA (shRNA) or RE inhibition with tetramerization-blocking peptides, and at the promoter H3K27me3 is replaced by the activating chromatin mark H3K9ac as well as by RNA polymerase II. Upregulation of PSGL-1 restores the binding of cells to P- and E-selectin and re-establishes myeloid-specific cellular adhesion while it fails to bind to lymphocyte-specific L-selectin. Overall, our data suggest that the RE oncoprotein epigenetically represses PSGL-1 via binding to its promoter region and thus affects the adhesive behavior of t(8;21)+ AML cells

New Psychoactive Substances in the Homeless Population: A Cross-Sectional Study in the United Kingdom

The last few years have seen the emergence of new psychoactive substance among the homeless population, specifically synthetic cannabinoid receptor agonists. The purpose of this study is to investigate the knowledge and experiences of new psychoactive substances amongst users from the homeless population. An explanatory research design was applied using a semi-structured questionnaire with the focus on gaining insights on the prevalence, motivations and effects. Participants were recruited through convenience sampling from support organisations and charities UK-wide. Descriptive statistics and logistic regression were applied to analyse the data obtained from participant surveys. A total of 105 participants met the inclusion criteria and were in the age range of 18 to 64 years old. Almost 70% consumed new psychoactive substance products, which “Spice” was the most prevalent substance. Homeless users had consumed new psychoactive substance to escape reality and to self-treat themselves and stopped consumption due to the adverse effects. Adverse events were reported from the majority of the participants and led to more than 20% of the participants requiring medical treatment following hospitalisation. Findings from this study can contribute to the development of guidelines and policies that specifically address the needs of the homeless population who use new psychoactive substances

Authentication of Antibiotics Using Portable Near-Infrared Spectroscopy and Multivariate Data Analysis

Counterfeit medicines represent a global public health threat warranting the development of accurate, rapid, and nondestructive methods for their identification. Portable near-infrared (NIR) spectroscopy offers this advantage. This work sheds light on the potential of combining NIR spectroscopy with principal component analysis (PCA) and soft independent modelling of class analogy (SIMCA) for authenticating branded and generic antibiotics. A total of 23 antibiotics were measured “nondestructively” using a portable NIR spectrometer. The antibiotics corresponded to six different active pharmaceutical ingredients being: amoxicillin trihydrate and clavulanic acid, azithromycin dihydrate, ciprofloxacin hydrochloride, doxycycline hydrochloride, and ofloxacin. NIR spectra were exported into Matlab R2018b where data analysis was applied. The results showed that the NIR spectra of the medicines showed characteristic features that corresponded to the main excipient(s). When combined with PCA, NIR spectroscopy could distinguish between branded and generic medicines and could classify medicines according to their manufacturing sources. The PCA scores showed the distinct clusters corresponding to each group of antibiotics, whereas the loadings indicated which spectral features were significant. SIMCA provided more accurate classification over PCA for all antibiotics except ciprofloxacin which products shared many overlapping excipients. In summary, the findings of the study demonstrated the feasibility of portable NIR as an initial method for screening antibiotics

Control of a population of battery energy storage systems for frequency response

The control of multiple battery energy storage systems (BESSs) to provide frequency response will be a challenge in future smart grids. This paper proposes a hierarchical control of BESSs with two decision layers: the aggregator layer and the BESS control layer. The aggregator layer receives the states of charge (SoC) of BESSs and sends a command signal to enable/disable the BESS control layer. The BESS controller was developed to enable the BESSs to respond from the highest to lowest SoC when the frequency drops, and from lowest to highest when it rises. Hence, the BESS’s response is prioritised to reduce the impact on the power system and end-users during the service. The BESS controller works independently when a failure occurs in the communication with the aggregator. The dynamic behaviour of the population of the controllable BESSs was modelled based on a Markov chain. The model demonstrates the value of aggregation of BESSs for providing frequency response and evaluates the effective capacity of the service. The model was demonstrated on the 14-machine South-East Australian power system with a 14.5 GW load. 254 MW of responsive capacity of aggregated batteries was effective in reducing the system frequency deviation below 0.2 Hz following a sequence of disturbances