235 research outputs found

    Polynomial Models to Study and Present Within-Tree Variation of Wood Properties

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    A method is presented for obtaining information on within-tree variation for wood properties. The polynomial models resulting from this study provide a technique for statistical analysis and for plotting within-tree variation patterns of fiber, vessel, and ray percentages as well as ring widths. With this method, it is possible to examine the oblique, horizontal, and vertical variation patterns of different wood properties, both statistically and graphically; hence, statistical inference can conveniently be made on within-tree patterns of variation. This can provide not only information of value in tree improvement work, but also a better understanding of the variability of wood

    Some Structural Changes Observed in the Transformation of Wood into Charcoal1

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    On the basis of measurements of microtomed cubes of white oak and on resultant charcoal, dimensional changes occurring on the conversion of wood into charcoal are: tangential, -25.68%, radial, -15.45%, and longitudinal, -11.43%. Light microscopic examination of charcoal reveals residues of combustion present in cell cavities. Electron microscopic examination indicates that the original fibrillar arrangement of the cell wall has been replaced with a smooth, "amorphous-appearing" wall structure

    Hydration Characteristics of Limestone Filled Cement Pastes

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    The physico-mechanical properties of hardened limestone-filled cement pastes were studied. Five filled-cements were prepared from 0, 5, 10, 15 and 20 wt. % of limestone and OPC. The water of consistency of filled-cement pastes was 0.275, 0.275, 0.275, 0.272, and 0.270, respectively. The pastes are moulded into one inch cubic moulds and left within the moulds at 100% relative humidity for 24 h, then demoulded and cured under tap water for 3, 7, 28, and 90 days. At each hydration time, the combined water, bulk density, total porosity and compressive strength of the hardened filled-cement pastes were determined. Some selected filled-cement pastes were investigated using differential thermal analysis (DTA) and scanning electron microscope (SEM) Techniques. Addition of limestone to Portland cement causes an increase of hydration at early ages inducing a high early strength, but it can reduce the later strength due to the dilution effect. The results indicate that the addition of limestone up to 5 wt. % improves the physico-mechanical properties of ordinary Portland cement which acts as a nucleating agent and accelerates the hydration of filled cement pastes. The addition of 5 wt. % limestone can be used in the production of portland cement according to the international specifications. On the other side, the addition of 10-20 wt. % limestone can be used in the production of blended or mixed cements

    Prevalence of Acute Coronary Syndrome in Patients Suspected for Pulmonary Embolism or Acute Aortic Syndrome: Rationale for the Triple Rule-out Concept.

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    BACKGROUND: The aims of the study were to evaluate the prevalence of acute coronary syndrome (ACS) among patients presenting with atypical chest pain who are evaluated for acute aortic syndrome (AAS) or pulmonary embolism (PE) with computed tomoangiography (CTA) and discuss the rationale for the use of triple rule-out (TRO) protocol for triaging these patients. METHODS: This study is a retrospective analysis of patients presenting with atypical chest pain and evaluated with thoracic (CTA), for suspicion of AAS/PE. Two physicians reviewed patient files for demographic characteristics, initial CT and final clinical diagnosis. Patients were classified according to CTA finding into AAS, PE and other diagnoses and according to final clinical diagnosis into AAS, PE, ACS and other diagnoses. RESULTS: Four hundred and sixty-seven patients were evaluated: 396 (84.8%) patients for clinical suspicion of PE and 71 (15.2%) patients for suspicion of AAS. The prevalence of ACS and AAS was low among the PE patients: 5.5% and 0.5% respectively (P = 0.0001), while the prevalence of ACS and PE was 18.3% and 5.6% among AAS patients (P = 0.14 and P = 0.34 respectively). CONCLUSION: The prevalence of ACS and AAS among patients suspected clinically of having PE is limited while the prevalence of ACS and PE among patients suspected clinically of having AAS is significant. Accordingly patients suspected for PE could be evaluated with dedicated PE CTA while those suspected for AAS should still be triaged using TRO protocol

    Windbreak-Grown Casuarina and Eucalyptus Trees for Unbleached Kraft Pulp

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    A laboratory-scale evaluation was conducted of juvenile windbreak-grown Casuarina and Eucalyptus trees for kraft pulp production. Test results of unscreened pulp yields, pulp chemical analyses, and handsheet physical properties indicated that windbreak-grown materials are suitable for unbleached kraft pulp. Casuarina gave the best pulp yield and had higher tear strength than Eucalyptus, but both species were superior to kraft pulps from agricultural raw materials such as rice straw and Thymelia, which are currently used in Egypt. For both species, the best kraft pulping schedule tested was a 4:1 liquor-to-wood ratio with 20% active alkali with additional conditions constant. Scanning electron micrographs of handsheets helped explain the observed differences in physical properties between the two species. Mixing of Casuarina and Eucalyptus raw material prior to pulping shows promise for unbleached kraft pulp production

    Effect of type of mixing water and sand on the physico–mechanical properties of magnesia cement masonry units

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    AbstractThis study has been conducted to investigate the influences of sand addition and mixing waters with different ratios on the physico-mechanical properties of magnesium oxychloride cement (MOC) masonry units. Three mixtures (M, MI and MII) were prepared to make magnesium oxychloride cement from the sand dunes as a filler material with some different additives. The mixture (M) was prepared by seawater instead of tap water in the mixing process, other mixtures (MI & MII) used drinking water. The physico-mechanical properties were studied in means of determination of bulk density, water absorption and compressive strength of the hardened MOC specimens cured in air at the lab ambient conditions for 3, 7, and 28days. It was recognized that the compressive strengths decreased with the increase of sand dunes content. The specimens of the all cured mixtures fulfilled superior properties compared with the required limits for concrete and limestone masonry units of a heavy density type. Also, it was found that using of the seawater leads to increase the physico-mechanical properties of the MOC specimens and can be used as mixing water in the manufacture of masonry units instead of the traditional drink water after ensuring of the other demanded governing properties

    Clinical audit of neonatal care in Assiut Women's Health Hospital, Egypt

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    Background: The current study aims to auditing the current care of healthy full term newborns in the delivery room and identify the gap between the current practice and ideal practice in Assiut Women's Health Hospital, Egypt.Methods: The current study was a clinical audit carried out in Assiut Woman Health Hospital, in the period from 1 September 2016 to 28 February 2017.The study included all newborns delivered in the delivery word of gestational age after 37 week. We excluded all Preterm babies, those with congenital anomalies, pregnant women with medical disorders and multiple pregnancies. In the present work all data was collected prospectively through direct personal patient contact, direct observation of care givers, patient interactions and attitudes, from the clinical records and then recording the data in special check sheet. All basic criteria of the study participants as age, parity, gestational age at delivery and type of delivery were obtained. The neonatal gender, weight, heart rate and respiratory rate were checked. Audit criteria were selected according to the WHO 2015 and AAP 2010-2015 guidelines.Results: The study included 800 women; the mean age of the women was 26.52±5.70 years. The mean parity was 1.78±1.85. The mean gestational age at delivery was 38.81±0.96 weeks. As regard the type of delivery, 54.1% of women were delivered by cesarean section. Calling neonatologists occurred in 67.9% of deliveries. The mean birth weight was 3.17±0.39 kilograms. Nearly half of them (52%) were males.Conclusions: Application of the guidelines of the neonatal handling is important for optimum care to the neonates. Re-audit the steps of the handling is important to discuss whether practice has improved or not in our tertiary hospital

    Mathematical Description of the Change in Properties of Casuarina Wood Upon Exposure to Gamma Radiation. 1. Changes in the Compressive and Tensile Strength

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    Casuarina cunninghamiana specimens were exposed to gamma-radiation doses ranging from 104 to 108 rad and tested in compression and tension parallel to grain. The percentage values of the irradiated specimens relative to that of the matched control (Y) were determined. The relationship between (Y) and log gamma radiation dose (X) was represented mathematically by the equation: Y = aXbcx. This equation described the change in compressive and tensile strength very well as was detected from the high correlation coefficients. Generally these properties increased slightly at low levels of radiation, reached a maximum, then decreased gradually thereafter. The reduction in tensile strength was more pronounced than in compressive strength.The threshold dose, i.e., the dose beyond which the properties began to decrease, was calculated. This dose ranged from 3.69 x 106 to 3.76 x 106 rad for compressive strength properties and from 1.51 x 106 to 1.70 x 106 rad for tensile strength properties. This indicated that irradiated casuarina wood had a greater resistance to compression than to tension

    EFFECT OF SOME IRRIGATION LEVELS AND FOLIAR-SPRAY APPLICATION WITH SOME CHEMICAL SUBSTANCES ON GROWTH AND YIELD OF SALVIA HISPANICA IN EGYPT

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    This study was carried out in two successive seasons (2014-2015 and 2015-2016) at SEKEM company Farm (Bilbase, Sharkya Governorate) on chia (Salvia hispanica) plant which is  a new crop introduced lately to Egyptian cultivation as  a medicinal plant. The effect of three irrigation levels of different reference evapotranspiration (80, 100 and 120 % ETo) with foliar application of three levels of proline (100, 200 and 300 ppm), salicylic acid (200, 400 and 600 ppm) and putrescine (10, 15 and 20 ppm) in addition to the control treatment (tap water) was investigated on growth and yield of Salvia hispanica cultivated in sandy loam soil with drip irrigation system. The results of the two years experiments indicated that the highest values of plant growth parameters and seeds yield of S. hispanica were obtained from 100 % ETo. While 120 % ETo resulted in the maximum value of roots fresh and dry weights. Foliar-spray application of proline (100 ppm.), salicylic acid (200 ppm) and putrescine (10 ppm) resulted in optimum fresh and dry weights of herbage and roots. Seed yield was higher in plants sprayed with proline (100 ppm) and putrescine (10 ppm), although the differences between them and salicylic acid (200 and 400 ppm) or putrescine (15 ppm) were insignificant in both seasons. This leads us to recommend irrigation of S. hispanica accordingly with 100 % ETo coupled with foliar-spray application of salicylic acid (200 ppm) from the economic point of view

    Analytical expressions for inductances of 3D air core inductors for integrated power supply

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    This work presents analytical expressions for the DC inductance of 3D air core inductors with circular cross section pillars (CCSP) and rectangular cross section pillars (RCSP). We consider the following four types of inductor structures: (1) a toroid with CCSP; (2) a toroid with RCSP; (3) a solenoid with RCSP; and (4) a solenoid with CCSP. For each type, a unique analytical model is developed for obtaining DC inductance. High frequency (1-100 MHz) effects on inductance are also discussed. The inductance values predicted by the proposed analytical models of the first three types of inductor structures are in an acceptable agreement with numerical Finite Element Analysis (FEA) solutions, where the maximum difference is 7.3%. Also, our analytical model for the fourth type inductor reduces the error, when correlated with FEA inductance value, up to 6× compared to previously published models. A comparison of results using proposed analytical expressions with published measured values as well as our measurement data demonstrates error ranging from 0.5 to 16.2%, while conventional formulae show errors of up to 143%. The results of the proposed models could serve as a good initial estimate for power supply on chip (PwrSoC) and power supply in package (PSiP) applications
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