General Modified Friedmann Equations in Rainbow Flat Universe, by Thermodynamics

We investigate the derivation of Friedmann equations in Rainbow gravity following Jacobson thermodynamic approach. We do not restrict the rainbow functions to be constant as is customarily used, and show that the first law of thermodynamics with a corresponding `classical' proportionality between entropy and surface area, supplemented eventually by a `quantum' logarithmic correction, are not in general sufficient to obtain the equations in flat FRW metrics.Comment: 7 pages, to appear in EPJ

Reinforced concrete two-span continuous deep beams

Ye

Cooperative Access in Cognitive Radio Networks: Stable Throughput and Delay Tradeoffs

In this paper, we study and analyze fundamental throughput-delay tradeoffs in cooperative multiple access for cognitive radio systems. We focus on the class of randomized cooperative policies, whereby the secondary user (SU) serves either the queue of its own data or the queue of the primary user (PU) relayed data with certain service probabilities. The proposed policy opens room for trading the PU delay for enhanced SU delay. Towards this objective, stability conditions for the queues involved in the system are derived. Furthermore, a moment generating function approach is employed to derive closed-form expressions for the average delay encountered by the packets of both users. Results reveal that cooperation expands the stable throughput region of the system and significantly reduces the delay at both users. Moreover, we quantify the gain obtained in terms of the SU delay under the proposed policy, over conventional relaying that gives strict priority to the relay queue.Comment: accepted for publication in IEEE 12th Intl. Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Wireless Networks (WiOpt), 201

Influence of novel techniques on solubility, mechanical properties and permeability via hot melt extrusion technology

Hot melt extrusion (HME) was evaluated as a continuous processing technology for the manufacture of solid dispersions. The aim of the current research project was to study the effect of pressurized carbon dioxide (P-CO2) on the physico-mechanical properties of three different grades of cellulose polymers, Klucel™ ELF, EF and LF hydroxypropylcellulose (HPC) resulting from hot melt extrusion techniques, and to assess the plasticization effect of P-CO2 on the tested polymers. The physico-mechanical properties as well as the tablet characteristics of the extrudates with and without injection of P-CO2 and with non-extruded polymers were examined. P-CO2 acted as plasticizer for Klucel™ LF, EF and ELF and allofor a reduction in processing temperature during the extrusion process by 20°C as compared to the processing temperature without injecting P-CO2. Furthermore, the CO2 served as a pore former and produced foam-like structure extrudates. This morphological change resulted in an increase in bulk and tap density as well as surface area and porosity. Additionally, the hardness of the tablets of the polymers with P-CO2 was increased compared to polymer processed without P-CO2 and the non-extruded polymer. Moreover, the % friability of the tablets improved using P-CO2 processed polymer. Thus good binding properties and compressibility of the extrudates were positively influenced utilizing P-CO2 processing. The interest to incorporate a model was increased to investigate the effect of pressurized carbon dioxide (P-CO2) on the physico-mechanical properties as well as the drug release behavior. Ketoprofen (KTP), used as a model drug, was incorporated with hydroxypropylcellulose (HPC) (Klucel™ ELF, EF and LF) as a polymeric carrier to produce KTP amorphous solid dispersion using HME technique. Thermal gravimetric analysis (TGA) was used to evaluate and confirm the formulations thermal stability. Differential Scanning Calorimetery (DSC) was performed to evaluate the physical state of KTP in the extrudates. The microscopic morphology of the extrudates was changed to a foam-like structure due to expansion of the CO2 at the extrusion die. The foamy extrudates demonstrated enhanced KTP release compared to the extrudates processed without P-CO2 due to the increase in porosity and surface area of those extrudates. The moisture content of the extrudates processed with P-CO2 was slightly increased and this played a significant role in increasing KTP tablet hardness and decreasing percent friability. A concern with HME is the limitation of the drug loading due to drug-polymer miscibility. In order to solve this issue, we investigated the effect of foam like structure produced by pre P-CO2 on the drug loading and the dissolution profile of carbamazepine (CBZ) and low molecular weight hydroxypropylcellulose (HPC) matrices using HME technique. The resulted extrudates with P-CO2 injection exhibited higher surface area and porosity compared to the extrudates processed without P-CO2. Moreover, the CBZ release profile of the 20-50% drug load formulations processed with P-CO2 injection shoalmost complete drug release within 2 hours. In contrast, the drug release profiles of 20%, 30%, 40% and 50% CBZ/ Klucel™ ELF formulations processed without P-CO2 injection exhibited 90%, 86%, 80% and 73% CBZ drug release, respectively. In conclusion, HME processing assisted with P-CO2 increased the drug loading capability of CBZ in KlucelTM ELF polymeric matrix as well as optimized CBZ drug- release profiles. Drug permeability and dissolution rate are considered as key to predict the drug bioavailability. HME was used as an approach to improve solubility and permeability of the psychoactive natural product piperine. Piperine 10–40% w/w formulated in Eudragit® EPO/ Kollidon® VA 64 or Soluplus® formulation was used in this study to investigate the efficiency of various polymers to enhance the solubility and permeability of piperine via HME technique to ultimately increase its systemic absorption of the compound. Scanning electron microscopy (SEM) images shoabsence of crystals in 10% w/w piperine/Soluplus® indicating that piperine was dispersed in the Soluplus® polymer carrier in its amorphous form. However, crystals were evident in all other formulations with different ratios. Solubility of 10% and 20% piperine/Soluplus® was increased more than 160 and 45 folds in water, respectively. Furthermore, permeability studies using non- everted rat intestinal sac model demonstrated the enhancement in piperine absorption of the 10% w/w piperine/Soluplus® extrudates up to 158.9 ?g/5mL compared to 1.4 ?g/5mL in the case of pure piperine within 20 minutes

Shrinkage of natural plaster materials for straw bale buildings affected by reinforcement fibers and drying

This study was carried out to determine the shrinkage percentage of natural plaster materials consisted of soil, sand and different fibers.  Straw was used as a reinforcement fiber for plaster and three types of fibers.  The plaster materials were put under drying temperatures of 30℃, 50℃ and 70℃.  The results revealed that the highest shrinkage was for plaster reinforced by wood shavings fibers, while the lowest shrinkage was for plaster reinforced by barley straw fibers for treatments A, B and C.  Also, the plaster without reinforcement fibers had a lot of cracks and problems that destroyed plaster.  The reinforcement fiber had a greater effect on the drying shrinkage than sand.  The study indicates that drying the plaster at 30℃ with a lot of straw can decrease the shrinkage and cracks.Keywords: shrinkage percentage, drying temperature, earth plaster, sand, straw, straw bale buildings Citation: Ashour, T., and A. Derbala.  Shrinkage of natural plaster materials for straw bale buildings affected by reinforcement fibers and drying.  Agric Eng Int: CIGR Journal, 2010, 12(1): 55-62

Modified ACI Drop-Weight Impact Test for Concrete.

yesACI Committee 544’s repeated drop-weight impact test for concrete is often criticized for large variations within the results. This paper identifies the sources of these large variations and accordingly suggests modifications to the ACI test. The proposed modifications were evaluated and compared to the current ACI test by conducting impact resistance tests on 40 specimens from two batches of polypropylene fiber-reinforced concrete (PPFRC). The results obtained from both methods were statistically analyzed and compared. The variations in the results were investigated within the same batch and between different batches of concrete. The impact resistance of PPFRC specimens tested with the current ACI test exhibited large coefficients of variation (COV) of 58.6% and 50.2% for the first-crack and the ultimate impact resistance, respectively. The corresponding COV for PPFRC specimens tested according to the modified technique were 39.4% and 35.2%, indicating that the reliability of the results was significantly improved. It has been shown that, using the current ACI test, the minimum number of replications needed per each concrete mixture to obtain an error below 10% was 41 compared to 20 specimens for the modified test. Although such a large number of specimens is not good enough for practical and economical reasons, the reduction presents a good step on the development of a standard impact test

The single nucleotide polymorphism rs2305957 G/A is not associated with recurrent pregnancy loss

Background: This study was conducted in order to investigate the association between the single nucleotide polymorphism (SNP) rs2305957 G/A and recurrent pregnancy loss (RPL) in a group of Palestinian women residing in Gaza strip.Methods: A retrospective case-control study was carried out during the period (May to August, 2015). A total of 380 females, 190 RPL patients and 190 control women without previous history of RPL, aged 20–35 years were included in the study. The SNP was analyzed by tetra-primer amplification refractory mutation system PCR (T-ARMS-PCR).Results: No statistically significant difference existed between RPL cases and controls in terms of the allelic and genotypic distribution of rs2305957 G/A.Conclusions: SNP rs2305957 G/A does not represent a risk factor for RPL in the investigated population