In the present investigation an attempt was made to enhance the solubility and dissolution of poorly soluble drug, isotretinoin, by formulating self-nanoemulsifying drug delivery system (SNEDDS). Liquid SNEDDSs were prepared using Transcutol P as oil, Tween 80 as surfactant, and PEG 400 as cosurfactant. Pseudoternary phase diagrams were constructed to identify the efficient self-nanoemulsification region. The formulation with 40&#x25; oil (Transcutol P) and 60&#x25; surfactant: cosurfactant (Tween 80: PEG 400) ratio of 1&#x2009;:&#x2009;1 was optimized based on evaluation parameters for droplet size analysis, self-emulsification capacity, zeta potential, and in vitro drug release performance. The optimized system contains mean droplet size of 36.60&#x2009;nm and zeta potential (&#x3b6;) &#x2212;26.73&#x2009;mV. The optimized formulation A1 was adsorbed onto Fujicalin to produce solid SNEDDS, which exhibited good flow properties and preserved the self-emulsification properties of liquid SNEDDS. The differential scanning calorimetry, FT-IR studies of solid SNEDDS revealed transformation of isotretinoin into molecularly dissolved state in the liquid SNEDDS. In vitro dissolution profiles showed that dissolution rate of ISN from solid SNEDDS was significantly greater as compared to pure drug.

Hitesh Chavda

Jaimeen Patel

Gordhan Chavada

Shruti Dave

Ankini Patel

Chhagan Patel

Self-Nanoemulsifying Powder of Isotretinoin: Preparation and Characterization

Aggregation state of silver nanoparticles dispersed in an aqueous solution greatly varies with storage and treatment conditions. In this study, silver nanoparticles synthesized in chitosan solution by a chemical reduction method were hydrothermally treated at different temperatures. The variation in the aggregation state of silver nanoparticles in the solution was observed by UV-Vis spectroscopy and field emission transmission electron microscopy. Results indicated that a phase transition occurred while silver nanoparticles were hydrothermally treated for 5 h at 100 and <svg style="vertical-align:-0.20473pt;width:40.950001px;" id="M1" height="13.1875" version="1.1" viewBox="0 0 40.950001 13.1875" width="40.950001" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,12.875)"><path id="x31" d="M384 0h-275v27q67 5 81.5 18.5t14.5 68.5v385q0 38 -7.5 47.5t-40.5 10.5l-48 2v24q85 15 178 52v-521q0 -55 14.5 -68.5t82.5 -18.5v-27z" /></g><g transform="matrix(.017,-0,0,-.017,8.222,12.875)"><path id="x32" d="M412 140l28 -9q0 -2 -35 -131h-373v23q112 112 161 170q59 70 92 127t33 115q0 63 -31 98t-86 35q-75 0 -137 -93l-22 20l57 81q55 59 135 59q69 0 118.5 -46.5t49.5 -122.5q0 -62 -29.5 -114t-102.5 -130l-141 -149h186q42 0 58.5 10.5t38.5 56.5z" /></g><g transform="matrix(.017,-0,0,-.017,16.381,12.875)"><path id="x30" d="M241 635q53 0 94 -28.5t63.5 -76t33.5 -102.5t11 -116q0 -58 -11 -112.5t-34 -103.5t-63.5 -78.5t-94.5 -29.5t-95 28t-64.5 75t-34.5 102.5t-11 118.5q0 58 11.5 112.5t34.5 103t64.5 78t95.5 29.5zM238 602q-32 0 -55.5 -25t-35.5 -68t-17.5 -91t-5.5 -105&#xA;q0 -76 10 -138.5t37 -107.5t69 -45q32 0 55.5 25t35.5 68.5t17.5 91.5t5.5 105t-5.5 105.5t-18 92t-36 68t-56.5 24.5z" /></g>

			<g transform="matrix(.012,-0,0,-.012,24.538,4.712)"><path id="x2218" d="M326 255q0 -56 -41 -96t-99 -40t-99 40t-41 96t41 96t99 40t99 -40t41 -96zM274 255q0 38 -25.5 65t-62.5 27t-62.5 -27t-25.5 -65t25.5 -65t62.5 -27t62.5 27t25.5 65z" /></g>

			<g transform="matrix(.017,-0,0,-.017,29.575,12.875)"><path id="x43" d="M614 175l29 -10q-33 -109 -57 -154q-121 -26 -184 -26q-90 0 -160.5 29t-112.5 77t-63.5 105.5t-21.5 119.5q0 157 108 253t277 96q36 0 71.5 -5t69 -13.5t36.5 -8.5q15 -102 20 -150l-29 -8q-20 79 -66.5 114t-128.5 35q-119 0 -187.5 -86t-68.5 -207&#xA;q0 -140 73.5 -227.5t188.5 -87.5q73 0 119.5 37.5t86.5 116.5z" /></g>

		
	
</svg>; however, they aggregated and completely precipitated at <svg style="vertical-align:-0.20473pt;width:40.950001px;" id="M2" height="13.1875" version="1.1" viewBox="0 0 40.950001 13.1875" width="40.950001" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,12.875)"><use xlink:href="#x31"/></g><g transform="matrix(.017,-0,0,-.017,8.222,12.875)"><path id="x35" d="M153 550l-26 -186q79 31 111 31q90 0 141.5 -51t51.5 -119q0 -93 -89 -166q-85 -69 -173 -71q-32 0 -61.5 11.5t-41.5 23.5q-18 17 -17 34q2 16 22 33q14 9 26 -1q61 -50 124 -50q60 0 93 43.5t33 104.5q0 69 -41.5 110t-121.5 41q-53 0 -102 -20l38 305h286l6 -8&#xA;l-26 -65h-233z" /></g><g transform="matrix(.017,-0,0,-.017,16.381,12.875)"><use xlink:href="#x30"/></g>

			<g transform="matrix(.012,-0,0,-.012,24.538,4.712)"><use xlink:href="#x2218"/></g>

			<g transform="matrix(.017,-0,0,-.017,29.575,12.875)"><use xlink:href="#x43"/></g>

		
	
</svg>. Mesoporous silver powder obtained by hydrothermal treatment at <svg style="vertical-align:-0.20473pt;width:40.950001px;" id="M3" height="13.1875" version="1.1" viewBox="0 0 40.950001 13.1875" width="40.950001" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,12.875)"><use xlink:href="#x31"/></g><g transform="matrix(.017,-0,0,-.017,8.222,12.875)"><use xlink:href="#x35"/></g><g transform="matrix(.017,-0,0,-.017,16.381,12.875)"><use xlink:href="#x30"/></g>

			<g transform="matrix(.012,-0,0,-.012,24.538,4.712)"><use xlink:href="#x2218"/></g>

			<g transform="matrix(.017,-0,0,-.017,29.575,12.875)"><use xlink:href="#x43"/></g>

		
	
</svg> was characterized by using X-ray diffraction technique, BET analyzer, and scanning electron spectroscope.

Dang Viet Quang

Nguyen Hoai Chau

The Effect of Hydrothermal Treatment on Silver Nanoparticles Stabilized by Chitosan and Its Possible Application to Produce Mesoporous Silver Powder

Using silicotetraetilortosilicate (TEOS) mixed with aluminum tri-sec-butoxide (TSBAI) or aluminum cloaures mullite ceramics were created by the sol-gel method. The quantities used of each substance were those that led to obtain stoichiometric mullite (3Al2O3&#x000B7;2SiO2). The experimental methodology used for obtaining mullite consisted in: sol-gel synthesis of precursor materials, isothermal treatment of those materials, and characterization of resulting materials. In order to determine the advance of reactions during mullite formation, isothermal treatments between 300&#xb0;C and 1600&#xb0;C were performed, keeping the samples at each temperature during 4&#x2009;h. From XRD results, it may be said that precursor powders originally amorphous start to crystallize in Al2O3 and SiO2 at 1200&#xb0;C, and the mullite formation starts at 1200&#xb0;C, with being completed at 1600&#xb0;C. The use of TSBAI favors the formation of mullite crystals at lower temperature. From SEM observations a microstructure that presents primary mullite with randomly oriented grains of secondary mullite with acicular shapes and sizes that range between 1.25 and 1.50&#x2009;<svg style="vertical-align:-3.56265pt;width:9.5625px;" id="M1" height="12.175" version="1.1" viewBox="0 0 9.5625 12.175" width="9.5625" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><path id="x1D707" d="M538 96q-38 -45 -84 -76.5t-71 -31.5q-44 0 -15 117q12 49 18 89h-2q-99 -128 -163 -178q-36 -28 -70 -28q-26 0 -44 38h-2q-16 -69 -16 -129q0 -43 11 -75.5t24 -42.5l1 -6q-7 -12 -24.5 -23t-37.5 -11q-40 0 -40 76q0 52 35 202l94 407l78 24l5 -5q-32 -122 -72 -310&#xA;q-7 -33 0 -55t25 -22q36 0 105.5 75t107.5 145l32 146l75 26h10q-50 -197 -78 -347q-7 -38 6 -38q7 0 31 17t47 39z" /></g>

		
	
</svg>m long may be determined.

Lucia T&#xe9;llez Jurado

Rosa Mar&#xed;a Ar&#xe9;valo Hern&#xe1;ndez

Enrique Rocha-Rangel

Sol-Gel Synthesis of Mullite Starting from Different Inorganic Precursors

The deformation characteristics during open-die forging of silicon carbide particulate reinforced aluminium metal matrix composites (SiCp AMC) at cold conditions are investigated. The material was fabricated by liquid stir casting method in which preheated SiC particles were mixed with molten LM6 aluminium casting alloy and casted in the silicon mould. Finally, preforms obtained were machined in required dimensions. Two separate cases of deformation, that is, open-die forging of solid disc and solid rectangular preforms, were considered. Both upper bound theoretical analysis and experimental investigations were performed followed by finite element simulation using DEFORM, considering composite interfacial friction law, barreling of preform vertical sides, and inertia effects, that is, effect of die velocity on various deformation characteristics like effective stress, strain, strain rate, forging load, energy dissipations, and height reduction. Results have been presented graphically and critically investigated to evaluate the concurrence among theoretical, experimental, and finite element based computational findings.

Deep Verma

P. Chandrasekhar

S. Singh

S. Kar

Investigations into Deformation Characteristics during Open-Die Forging of SiCp Reinforced Aluminium Metal Matrix Composites

Structural ceramics are superior to metallic materials in terms of their high-temperature strengths and critical heat proof temperatures. However, compared to metallic materials, ceramics exhibit lower fracture toughness, so they are more sensitive to flaws such as pores and cracks. The shortness considerably decreases the component reliability. To overcome the shortness, in this study, special attention is paid to structural ceramics with self-crack-healing ability. There are several advantages for using a material with self-crack-healing ability. (1) After an efficient machine operation, the materials are able to self-heal the cracks introduced by the machining. (2) The materials are able to self-heal the cracks introduced during service and recover the strength completely at healing temperature. However, ways of organizing the available knowledge to increase the through-life reliability of ceramics components have not been extensively studied. The authors propose a new concept and the corresponding flowchart. This new concept is a promising technique for increasing the through-life reliability of ceramics components with excellent self-crack-healing ability.

Kotoji Ando

Koji Takahashi

Wataru Nakao

Toshio Osada

Kae Iwanaka

New Technology for Increasing Through-Life Reliability of Ceramics Components Using Self-Crack-Healing Ability

Ceramics have been used as bearing and cutting tool components, which are subjected to contact loading during their operation. The presence of surface cracks on these components decreases their contact strength. Thus, the reliability of ceramic components can be increased by improving their contact strength through crack healing. In the present study, the effects of crack healing on the contact strength of a silicon carbide-(SiC-) reinforced silicon nitride (Si3N4) composite subjected to various machining processes were investigated. The contact strength of this composite was evaluated using a sphere indentation test in which acoustic emission was used. The results showed that the contact strength of the composite improved when it was subjected to crack healing in combination with rapping; this was true even when the composite had cracks due to a heavy machining process.

Keita Takahashi

Improvement in Contact Strength of Si3N4/SiC Composite by Crack Healing

Crack healing behavior of SiC ceramics with large crack width has been studied as a function of coating and heat treatment. The SiO2 colloid coating was carried out on two types: hydrostatic pressure coating and roll coating. The crack healing was one hour at 1173&#x2009;K in air. The crack part formed SiO2 oxides until the critical times by a hydrostatic pressure method. The crack does not anymore heal if it exceeds the critical times. The crack part and the base part have many O components and Si components regardless of the times of coating and heat treatment. The combined hydrostatic and rolling coating method did not have nearly an effect on crack-healing for large crack width over 1.4&#x2009;<svg style="vertical-align:-3.56265pt;width:9.5625px;" id="M1" height="12.175" version="1.1" viewBox="0 0 9.5625 12.175" width="9.5625" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns="http://www.w3.org/2000/svg">
	
		
			<g transform="matrix(.017,-0,0,-.017,.062,7.675)"><path id="x1D707" d="M538 96q-38 -45 -84 -76.5t-71 -31.5q-44 0 -15 117q12 49 18 89h-2q-99 -128 -163 -178q-36 -28 -70 -28q-26 0 -44 38h-2q-16 -69 -16 -129q0 -43 11 -75.5t24 -42.5l1 -6q-7 -12 -24.5 -23t-37.5 -11q-40 0 -40 76q0 52 35 202l94 407l78 24l5 -5q-32 -122 -72 -310&#xA;q-7 -33 0 -55t25 -22q36 0 105.5 75t107.5 145l32 146l75 26h10q-50 -197 -78 -347q-7 -38 6 -38q7 0 31 17t47 39z" /></g>

		
	
</svg>m. The study for more effective healing of a large crack width must be carried out in the future.

Ki Woo Nam

Effect of Crack Healing of SiC according to Times of SiO2 Colloid Coating

Al2O3/SiC composite ceramics with high crack-healing ability were subjected to shot peening (SP) using zirconium oxide shots with several peening pressures and shot diameters. Specimens subjected to SP were heat-treated in air to heal the surface cracks induced by SP. The residual stress, the apparent fracture toughness, and the Weibull distribution of the contact strength were investigated, revealing that the combination of SP and crack-healing is effective for increasing the contact strength and decreasing the scatter of the contact strength of Al2O3/SiC.

Tomoya Oki

Hiroki Yamamoto

Improvement of the Contact Strength of Al2O3/SiC by a Combination of Shot Peening and Crack-Healing

Phenomena-based models can be used in a predictive manner, but statistical modelling methods can also yield interesting findings and can serve as a tool for analysing the effects of different variables on the overall phenomenon. In addition, the generation of theoretical models can sometimes be limited due to the unideality of the studied system. Statistical modelling, in this case multiple-linear regression (MLR), was used to describe the effects of temperature and acid concentration on the dissolution of magnetite, Fe3O4 with oxalic acid. Whereas a linear model with an interaction term was sufficient in describing the dissolution of synthetic Fe3O4, a more complex full quadratic model had to be used to describe the dissolution of industrial Fe3O4 in the same conditions.

Riina Salmimies

Mikko Huhtanen

Juha Kallas

Antti H&#xe4;kkinen

The Solubility of Two Magnetite Powders in Oxalic Acid: Applicability of Empirical Modelling

This paper describes the development of a multidimensional population balance model (PBM) which can account for the dynamics of a continuous powder mixing/blending process. The PBM can incorporate the important design and process conditions and determine their effects on the various critical quality attributes (CQAs) accordingly. The important parameters considered in this study are blender dimensions and presence of noise in the inlet streams. The blender dynamics have been captured in terms of composition of the ingredients, (relative standard deviation) RSD, and (residence time distribution) RTD. PBM interacts with discrete element modeling (DEM) via one-way coupling which forms a basic framework for hybrid modeling. The results thus obtained have been compared against a full DEM simulation which is a more fundamental particle-level model that elucidates the dynamics of the mixing process. Results show good qualitative agreement which lends credence to the use of coupled PBM as an effective tool in control and optimization of mixing process due to its relatively fewer computational requirements compared to DEM.

Maitraye Sen

Atul Dubey

Ravendra Singh

Rohit Ramachandran

Mathematical Development and Comparison of a Hybrid PBM-DEM Description of a Continuous Powder Mixing Process

The shear wave velocity dependence on porosity was modelled using percolation theory model for the shear modulus porosity dependence. The obtained model is not a power law dependence (no simple scaling with porosity), but a more complex equation. Control parameters of this equation are shear wave velocity of bulk solid, percolation threshold of the material and the characteristic power law exponent for shear modulus porosity dependence. This model is suitable for all porous materials, mortars and porous rocks filled with liquid or gas. In the case of pores filled with gas the model can be further simplified: The term for the ratio of the gas density to the density of solid material can be omitted in the denominator (the ratio is usually in the range of (10&#x2212;4, 10&#x2212;3) for all solids). This simplified equation was then tested on the experimental data set for porous ZnO filled with air. Due to lack of reasonable data the scientists are encouraged to test the validity of proposed model using their experimental data.

J. Kov&#xe1;&#x10d;ik

&#x160;. Emmer

Correlation between Shear Wave Velocity and Porosity in Porous Solids and Rocks

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Journal of Powder Technology