Thermal expansion and pressure effect in MnWO4

MnWO4 has attracted attention because of its ferroelectric property induced by frustrated helical spin order. Strong spin-lattice interaction is necessary to explain ferroelectricity associated with this type of magnetic order.We have conducted thermal expansion measurements along the a, b, c axes revealing the existence of strong anisotropic lattice anomalies at T1=7.8 K, the temperature of the magnetic lock-in transition into a commensurate low-temperature (reentrant paraelectric) phase. The effect of hydrostatic pressure up to 1.8 GPa on the FE phase is investigated by measuring the dielectric constant and the FE polarization. The low- temperature commensurate and paraelectric phase is stabilized and the stability range of the ferroelectric phase is diminished under pressure.Comment: 2 pages, 3 figures. SCES conference proceedings, houston, TX, 2007. to be published in Physica

Magnetic Phase Diagrams of Multiferroic Hexagonal RMnO3 (R=Er, Yb, Tm, and Ho)

The magnetic phase diagrams of RMnO3 (R = Er, Yb, Tm, Ho) are investigated up to 14 Tesla via magnetic and dielectric measurements. The stability range of the AFM order below the Neel temperature of the studied RMnO3 extends to far higher magnetic fields than previously assumed. Magnetic irreversibility indicating the presence of a spontaneous magnetic moment is found near 50 K for R=Er, Yb, and Tm. At very low temperatures and low magnetic fields the phase boundary defined by the ordering of the rare earth moments is resolved. The sizable dielectric anomalies observed along all phase boundaries are evidence for strong spin-lattice coupling in the hexagonal RMnO3. In HoMnO3 the strong magnetoelastic distortions are investigated in more detail via magnetostriction experiments up to 14 Tesla. The results are discussed based on existing data on magnetic symmetries and the interactions between the Mn-spins, the rare earth moments, and the lattice.Comment: 23 pages, 16 figures, to be published in JMR's Aug. focus issue on multiferroic

CORRELATING WRITER’S BLOCK AND ESL LEARNERS’ WRITING QUALITY

Despite the importance of writing in the language learners’ development, there are difficulties faced by English as a Second Language (ESL) learners that stem from various factors. One of them is the presence of writer’s block that could affect writing quality. Therefore, this study aims to describe writer’s block, along with a statistically-laden analysis of the possible correlation between the blocking experiences of 55 Filipino ESL learners and the levels of easability and readability of the essays they had written.  This research employed a descriptive-correlational design using The Questionnaire in Identifying Writer’s Block (QIWB) to gauge the extent of occurrence of writer’s block and the Coh-Metrix Common Core Text Easability and Readability Assessor (hereafter Coh-Metrix T.E.R.A.), an online computational tool, to measure the levels of easability and readability of the essays. The result shows that the learners generally experienced writer’s block, and their essays collectively showed high levels of easability on the basis of narrativity, referential cohesion, and deep cohesion. However, the essays were low in syntactic simplicity and word concreteness, while the level of readability computed exceeded that of the reading ability of 10th-grade learners. Test of correlation revealed that there exists negligible relationship between writer’s block and the overall easability and readability levels of the essays, though a significant but a weak relationship was documented between lateness and word concreteness and with premature editing and deep cohesion, respectively

Effect of dietary citric acid and microbial phytase on the growth performance of broiler chickens

Feed additives are one of the most essential parts of broiler production. Feed additives such as citric acid and microbial phytase are usually used separately despite the theory that they can work together. In this study, 320 broiler birds were reared and then fed four different treatments. 10 birds were reared per pen and there were 8 replications per treatment. The birds were reared using normal broiler management and health management protocols. The growth parameters and mortalities were recorded after each growth period. Production cost and the market price during the duration of the experiment were used to assess profitability. Out of all the treatments, the combination of the citric acid and microbial phytase gave the highest body weight, weight gain, second-lowest feed intake, best feed conversion ratio, and the highest profitability. Results indicated that there is a synergistic interaction with the combination of 3% citric acid and 500 U/kg microbial phytases. The concurrent supplementation produced a significant increase in the growth parameters and profitability

Benefits of Green Seaweed as Protein Source for Broiler: A Review

Poultry production contributes significantly to the agricultural economy. Nutrition is one important factor in having competent poultry production. Currently, there is a lot of research about natural alternatives or feed additives that are low in cost and can help increase the overall performance and improve poultry health conditions without any adverse effects. Macroalgae such as green seaweeds can meet these parameters. It is easily available and is considered a rich source of proteins, polysaccharides, carbohydrates, vitamins, minerals, pigments, and antioxidants. Most often, seaweeds are used as feed additives for broiler chickens as they can induce a beneficial impact on production parameters (body weight (BW), average daily gain (ADG), feed consumption (FC), and feed conversion ratio (FCR) and meat quality. However, there are several challenges in using green seaweed as a protein alternative for broiler chickens such as its toxic and antinutritional components, as well as varying available supply due to seasonal effects, diseases, location, and environmental pollution. Furthermore, the main objective of this review is to evaluate the different research conducted on green seaweed as a potential protein source in broilers

Strong spin-lattice coupling in multiferroic HoMnO3_{3}: Thermal expansion anomalies and pressure effect

Evidence for a strong spin-lattice coupling in multiferroic HoMnO_3 is derived from thermal expansion measurements along a- and c-axis. The magnetoelastic effect results in sizable anomalies of the thermal expansivities at the antiferromagnetic (T_N) and the spin rotation (T_{SR}) transition temperatures as well as in a negative c-axis expansivity below room temperature. The coupling between magnetic orders and dielectric properties below T_N is explained by the lattice strain induced by the magnetoelastic effect. At T_{SR} various physical quantities show discontinuities that are thermodynamically consistent with a first order phase transition

Low temperature dielectric anomalies in HoMnO_3: The complex phase diagram

The dielectric constant of multiferroic hexagonal HoMnO_3 exhibits an unprecedented diversity of anomalies at low temperatures (1.8 K< T <10 K) and under external magnetic fields related to magnetic phase transitions in the coupled system of Ho moments, Mn spins, and ferroelectric polarization. The derived phase diagram is far more complex than previously assumed including reentrant phases, phase transitions with distinct thermal and field hysteresis, as well as several multicritical points. Magnetoelastic interactions introduce lattice anomalies at the magnetic phase transitions. The re-evaluation of the T-H phase diagram of HoMnO_3 is demanded.Comment: 12 pages, 3 figure

Pressure-Temperature Phase Diagram of Multiferroic Ni3V2O8Ni_3V_2O_8

The pressure-temperature phase diagram of multiferroic $Ni_3V_2O_8$ is investigated for hydrostatic pressures up to 2 GPa. The stability range of the ferroelectric phase associated with the incommensurate helical spin order is reduced by pressure and ferroelectricity is completely suppressed at the critical pressure of 1.64 GPa at 6.2 K. Thermal expansion measurements at ambient pressure show strong step-like anomalies of the lattice parameters associated with the lock-in transition into the commensurate paraelectric phase. The expansion anomalies are highly anisotropic, the related volume change is consistent with the high-pressure phase diagram