Sufficient Hardness Research Articles

The role of local chemical hardness and van der Waals interactions in the anionic polymerization of alkyl cyanoacrylates

The polymers are stabilized appreciably by intra-chain dispersion forces. Localization of negative charge imparts sufficient local hardness for polymerization to continue independently of chain length.

Thickness optimization of auricular silicone scaffold based on finite element analysis

An optimized thickness of a transplantable auricular silicone scaffold was researched. The original image data were acquired from CT scans, and reverse modeling technology was used to build a digital 3D model of an auricle. The transplant process was simulated in ANSYS Workbench by finite element analysis (FEA), solid scaffolds were manufactured based on the FEA results, and the transplantable artificial auricle was finally obtained with an optimized thickness, as well as sufficient intensity and hardness. This paper provides a reference for clinical transplant surgery.

An attempt to produce blast furnace coke from Victorian brown coal

This paper describes attempts to produce blast furnace coke from Victorian brown coals. The attempted method involves combining a coal-derived binder with the original brown coal or its commercial products, briquettes. Briquetting of these mixtures gave composites that were then carbonized to form coke-like materials. Products were characterized by bulk density, helium density, compressive strength, reactivity, surface area, scanning electron microscopy and X-ray diffraction analysis. It was found that the products have sufficient compressive hardness to be used as coke but are still too reactive to be used in a blast furnace.

Shell hardening of unalloyed steel cylinders by high speed quenching

AbstractKobasko et al. have primarily shown that rapid water quenching can create compressive residual stresses near the surface and thereby a significant increase in the fatigue-limit (Intensive Quenching). Such processes result in an increase in hardness. Depending on steel grade, dimensions of the component and quenching intensity through hardening or only shell hardening will result. In this work, shell hardening processes were investigated in a more detailed manner for cylinders made of two different unalloyed steels. The goal of the work was discovering the general requirements to reach, on the one hand, a sufficient surface hardness paired with a non-through hardened hardening profile. On the other hand, compressive residual stresses in the near surface area should be as high as possible to achieve huge lifetime cycles for the heat treated work pieces. The experiments were carried out with a device that was especially developed for high speed quenching. As a quenching medium only tap water or water...

DEVELOPMENT OF HINGWASTAK CHURNA GRANULES AND TABLETS BY DRY GRANULATION TECHNIQUE FOR IMPROVING PATIENT COMPLIANCE

Ayurvedic formulary of India specifies the dose of Hingwastak churna to be 3-6 grams per day. It is difficult to swallow churna for patients. The objective of the present study was to develop Hingwastak churna granules and tablets with addition of organoleptic additives to improve the patient compliance. Granules and tablet formulations were developed by dry granulation (slugging) technique using different binders and other excipients. The granules were evaluated for angle of repose, tapped densities, compressibility index, organoleptic studies and stability study. The tablets were evaluated for weight uniformity, thickness, hardness, friability and disintegration time. Among the binding agents used 10% Avicel, CaCO3 and starch produced better granules with sufficient hardness and good flow properties. All the volunteers concurrently accepted the taste of Hingwastak churna granule formulation. Suitable formulation strategy can overcome the existing problem of Hingwastak churna.

Stress development and film formation in multiphase composite latexes

Designed appropriately, multiphase soft-core/hard-shell latex particles can achieve film formation without the addition of a coalescing aid, while preserving sufficient film hardness. Achieving optimal performance in these materials requires an understanding of how particle morphology affects film formation and stress development in the film. In this study, soft-core/hard-shell latex particles with different shell ratios, core and shell glass transition temperatures (T gs), and particle sizes (63–177 nm) were synthesized using a two-stage emulsion polymerization. The film formation behavior of the composite particles was investigated with cryogenic scanning electron microscopy, atomic force microscopy, and measurements of the minimum film formation temperature (MFFT). Results show that film formation was enhanced for particles with thinner hard shells, smaller particle size, and a smaller difference in T g between the core and shell polymers. For example, the MFFT decreased and the particle deformation increased for particles with thinner shells and smaller particle sizes. Stress development during drying was characterized using a cantilever beam bending technique. A walled cantilever design was used to monitor stress development without the complication of a lateral drying front. The film formation behavior and stress development correlated well with practical paint properties like scrub resistance and gloss.

Examination of the Electrolytic Polishing Metal Probe for the Cell Trap by an Electric Field

Generally, the metal probe for NSOM (Near field scanning optical microscopy) or STM (Scanning Tunneling Microscope) was made with gold or tungsten. However, they were not suitable for the cell trap in our research for the reasons of cost, hardness, etc. In our research, these problems were solved by choosing brass as a material of a probe. Since the probe production by electrolytic polishing can change the shape of the top, tip angle, and taper length etc, we can propose a probe suitable for a cell trap. Therefore, in this examination, we propose the brass probe by electrolytic polishing with low cost and sufficient hardness for cell trap.

Floating gastroretentive drug delivery systems: Comparison of experimental and simulated dissolution profiles and floatation behavior

IntroductionGastroretentive drug delivery systems (GRDDS) play an important role in the delivery of drug substances to the upper part of the gastrointestinal tract; they offer a possibility to overcome the limited gastric residence time of conventional dosage forms. AimsThe aim of the study was to understand drug-release and floatation mechanisms of a floating GRDDS based on functionalized calcium carbonate (FCC). The inherently low apparent density of the excipient (approx. 0.6g/cm3) enabled a mechanism of floatation. The higher specific surface of FCC (approx. 70m2) allowed sufficient hardness of resulting compacts. The floating mechanism of GRDDS was simulated in silico under simulated acidic and neutral conditions, and the results were compared to those obtained in vitro. MethodsUnited States Pharmacopeia (USP) dissolution methods are of limited usefulness for evaluating floating behavior and drug release of floating dosage forms. Therefore, we developed a custom-built stomach model to simultaneously analyze floating characteristics and drug release. In silico dissolution and floatation profiles of the FCC-based tablet were simulated using a three-dimensional cellular automata-based model. ResultsIn simulated gastric fluid, the FCC-based tablets showed instant floatation. The compacts stayed afloat during the measurement in 0.1N HCl and eroded completely while releasing the model drug substance. When water was used as dissolution medium, the tablets had no floating lag time and sank down during the measurement, resulting in a change of release kinetics. ConclusionsFloating dosage forms based on FCC appear promising. It was possible to manufacture floating tablets featuring a density of less than unity and sufficient hardness for further processing. In silico dissolution simulation offered a possibility to understand floating behavior and drug-release mechanism.

Properties of welded joints of metal structures after hardening deformation-heat treatment

The influence of deformation-heat treatment of welded joints from separate heating and using welding heat on the structure and properties of low-carbon steels for metal structures is considered in the paper. Some results of our research in this field are given. The main purpose of the research is to study the influence of the temperature gradient during welding and chemical composition of the structure formation in the basic and the weld metal, the possibilities of using welding heat for hardening welded joints of metal structures. Using technology for deformation-heat hardening of welded metal structures using welding heat will allow to reduce energy and labor expenditures, their manufacturing duration and increase the working efficiency on average by 1.2 times. The positive influence of deformation on forming an equilibrium structure in both the welded seam, and the heat-affected zone depending on the chemical composition of the weld metal is shown in the paper. The effect of carbon equivalent on the mechanical properties of welded joints is demonstrated. The research results can be used in manufacturing butt-welded joints of different designs, in particular pipelines at construction sites and plants. Using the obtained results will allow to improve the toughness of metal structures while maintaining sufficient hardness.

Novel Pullulan–Eudragit® S100 blend microparticles for oral delivery of risedronate: Formulation, in vitro evaluation and tableting of blend microparticles

Polymer blends have been considered a promising strategy to tailor drug release. In order to achieve gastroresistance and controlled release, Pullulan, a polysaccharide, and Eudragit® S100, an enteric polymer were selected to prepare microparticles for oral delivery of risedronate, an antiresorptive drug associated with GI tract injuries. Blend microparticles were prepared by spray-drying technique at 3 Pullulan and Eudragit® S100 ratios (MP2:1, MP1:1 and MP1:2) and were characterized in terms of yield, particle size, encapsulation efficiency, morphology, moisture content, flowability and in vitro drug release profiles. Microparticles presented yields between 31 and 42%, encapsulation efficiencies close to 100%, moisture contents lower than 11%, particle size ranging from 2.9 to 4.8μm and narrow distribution. In the gastric medium, MP1:2 showed the best gastroresistance profile. In the intestinal fluid, all samples were able to prolong drug release. MP1:2 was compressed into tablets with or without polyvinylpyrrolidone. Both tableted microparticles could be obtained with acceptable average weights, drug content close to 100%, sufficient hardness and low friability. In vitro studies showed that tablets maintained the gastroresistance observed for microparticles and were also able to prolong risedronate release. In conclusion, Pullulan/Eudragit® S100 microparticles are promising alternatives for the oral delivery of risedronate in the future.

Formulation optimization of hot-melt extruded abuse deterrent pellet dosage form utilizing design of experiments

The objective of this study was to develop techniques for an abuse-deterrent (AD) platform utilizing the hot-melt extrusion (HME) process. Formulation optimization was accomplished by utilizing Box-Behnken design of experiments to determine the effect of the three formulation factors: PolyOx WSR301, Benecel K15M and Carbopol 71G; each of which was studied at three levels on tamper-resistant (TR) attributes of the produced melt extruded pellets. A response surface methodology was utilized to identify the optimized formulation. Lidocaine hydrochloride was used as a model drug, and suitable formulation ingredients were employed as carrier matrices and processing aids. All of the formulations were evaluated for the TR attributes, such as particle size post-milling, gelling and percentage of drug extraction in water and alcohol. All of the design of experiments formulations demonstrated sufficient hardness and elasticity, and could not be reduced into fine particles (<150 μm), which is a desirable feature to prevent snorting. In addition, all of the formulations exhibited good gelling tendency in water with minimal extraction of drug in the aqueous medium. Moreover, Benecel K15M, in combination with PolyOx WSR301, could be utilized to produce pellets with TR potential. HME has been demonstrated to be a viable technique with a potential to develop novel AD formulations.

Casting made simple using modified sprue design: an in vitro study.

Success in dental casting restorations for fixed partial dentures (FPDs) depends on the castability. Castability is described as the ability of an alloy to faithfully reproduce sharp detail and fine margins of a wax pattern. The goal of a prosthodontist is to provide the patient with restorations that fit precisely. Regardless of the alloy used for casting, the casting technique should yield a casted alloy, which should possess sufficient mass, surface hardness and minimal porosity after casting. Twenty patterns for casting were made from three-dimensional printed resin pattern simulating a 3 unit FPD and casted using modified sprue technique. Later test samples were cemented sequentially on stainless steel model using pressure indicating paste and evaluated for vertical marginal gap in eight predetermined reference areas. Marginal gap were measured in microns using Video Measuring System (VMS2010F-CIP Corporation, Korea). A portion of the axial wall of the cast abutments depicting premolar and molar were sectioned and embedded in acrylic resin and tested for micro hardness using Reichert Polyvar 2 Met Microhardness tester (Reichert, Austria) and porosity using Quantimet Image Analyzer (Quantimet Corporation London, England). The results obtained for marginal gap, micro hardness, and porosity of all test samples were tabulated, descriptive statistics were calculated and the values were found to be within the clinically acceptable range. The new sprue technique can be an alternative and convenient method for casting which would minimize metal wasting and less time consuming. However, further studies with same technique on various parameters are to be conducted for its broad acceptance.

Effect of Heat Treatment Process of Sintered M3/2 High Speed Steel Parts

Dry machining is one of the ways to achieve a reduction of cooling lubricants, as well as reduced environmental pollution and lower health risk to workers. This leads to higher mechanical and thermal loading on cutting edges. The adaptation of cutting tools to the requirements of dry machining includes the optimisation of manufacturing technologies, the development of cutting materials of sufficient toughness and high hot hardness, the design of tool geometries as well as the coating of tools [.

Formulation and In Vitro Evaluation of Ofloxacin Tablets using Natural Gums as Binders.

Natural gums are economical, easily available, and useful as tablet binders. In the present investigation, an attempt was made to formulate Ofloxacin tablets using three natural binders, namely Acacia arabica, Hibiscus esculentus, and xanthan gum. Such six batches of Ofloxacin tablets were prepared by using different types and amounts of the natural binders by the wet granulation method. The tablets were analyzed for their hardness, friability, and weight variation, and in vitro release was performed in a phosphate buffer at pH 6.8. The prepared tablets were also evaluated for their various release kinetics and similarity factors f2. The physical properties of the tablets containing the natural binders showed sufficient hardness, desirable disintegration time, and low friability. Their better percentage of drug release was observed as compared to the marketed formulation showing more than 85% drug release within 45 minutes. The in vitro release data was well-fitted into zero-order and the values of release exponent ‘n’ were between 0.303 and 0.514. The high similarity factor f2 of 64.50 was achieved with the best batch in comparison to the marketed tablets. The results obtained indicated that the gum Acacia arabica performed as well as gelatin compared to the other binders for the Ofloxacin tablet formulation.

Evaluation and Diffusion Assessment for Surface Hardening Processes

The ability of heat is to change or modify the physical and mechanical characteristics of metals is an important aspect of manufacturing. The heat treatment processes is generally adapted to the processing of carbon steels in the production field. The content of carbon in mild steel is less than 0.3% and it requires sufficient hardness on surface of a component. Because of the lack of carbon, the metals to be processed under the carburizing Process. The carburizing process is diffuses carbon in to the surface of heat treated components in an atmosphere controlled furnace. The purpose of carburizing is to increases the surface carbon content, on the surface region or case depth/layer. Fick’s law describes the instantaneous flow of diffusing atoms in the case layer. This case depth is controlled by the diffusion of carbon atoms through the surface layers of the work piece and achieves maximum hardness during subsequent quench hardening in the surface hardening. The major types of surface hardening processes are: carburizing, carbonitriding and induction hardening. The objective is to improve the surface properties of a component, mainly in the hardness on the surface. These surface/case hardening operations are quite important also to static and dynamic strength with wear and seizure properties. In this article focused to an evaluation of surface hardening and the effects of diffusion layer formation during the heat treatment process are to be studied and analyzed.

FORMULATION AND EVALUATION OF SUSTAINED RELEASE TABLET OF DILTIAZEM HYDROCHLORIDE BY MELT GRANULATION TECHNOLOGY

The objective behind present study was to formulate and evaluate sustained release tablet of Diltiazem hydrochloride by using different polymers by melt granulation technology and to study the effect of various con centrations of polymers on release rate from tablet. T ablets were prepared using bees wax, carnauba wax, paraffin wa x as release ratardent polymers . The drug and excipient compatibility study was done by FTIR method using KBr pellet method . The granules pr epared by melt granulation technique evaluated for charac terization such as bulk density , tapped density, hausners ratio, angle of repose , cars index all granules shows good flow property. The tablet of Diltiazem HCL evaluated for characterizati on such as hardness, friability , weight variation and content uniformity all tablets shows sufficient hardness and friability shows that tablets are having sufficient strength . All results were satisfactory. The in vitro drug release studies for the prepared formulat ion were conducted for a period of 12 h using an EDT 08LX dissolution tester USP Type - II apparatus (rotating paddle) set at 100 rpm and a temperature of 37 ± 0.5°C formulation was placed in the 900 ml of the medium. For first 2 h tablet was placed in 1.2 pH acidic medium which was replaced with 7.4 pH phosp hate buffer for remaining 10 h . From the dissolution study and comparative graph it was concluded that increase in concentration of wax shows decrease in drug release from tablet. Batch F3 shows 99.84 % drug release at 12 h . In vitro release data of optimized formulations (Batch F3) was fitted to various kinetic models like zero order, first o rder, Higuchi, korsmeyer - peppas and pass Higuchi model as it has highest r 2

Risedronate-loaded Eudragit S100 microparticles formulated into tablets

Risedronate, an anti-osteoporotic drug, is associated with low patient compliance due to the upper gastrointestinal side-effects and stringent dosing regimes. This study aimed to prepare and characterize risedronate-loaded Eudragit® S100 microparticles and develop a final dosage form by the compression of microparticles using direct tableting excipients. Microparticles were prepared by spray-drying and presented yield of 54%, encapsulation efficiency higher than 90%, mean diameter of 3.3 µm, moisture content around 8% and exhibited spherical shape and poor flowability. At pH 1.2, 23% of risedronate was released from microparticles in 120 min, while at pH 6.8 the drug took 90 min to reach 99.5%. Microparticles were compressed into tablets using microcrystalline cellulose, magnesium stearate, colloidal silicon dioxide and 2 polyvinylpyrrolidone concentrations (5% and 15%). Tablets presented low variations in weight, thickness and drug content. Besides, the formulations showed sufficient hardness, low friability and disintegrated in less than 15 min. In acid medium, no more than 16% of the drug was released in 120 min, while in intestinal medium the formulations prolonged the risedronate release for 240 min. Finally, the developed tableted microparticles can be considered a promising dosage form for oral risedronate administration.

MOUTH DISSOLVING TABLETS: A REVIEW

Conventional dosage forms like tablets and capsules are now days facing the problems like dysphagia, resulting in the high incidence of non compliance and making the therapy ineffective. To obviate the problems associated with conventional dosage forms, mouth dissolving tablets have been developed having good hardness, dose uniformity, easy administration and serves as the first choice of dosage form for paediatrics, geriatrics and travelling patients. The MDTs were developed with an aim of having sufficient hardness, integrity and faster disintegration without water. Fast dissolving Tablets are disintegrating and/or dissolve rapidly in the saliva without the need for water. Some tablets are designed to dissolve in saliva remarkably fast, within a few seconds, and are true fast-dissolving tablets. Others contain agents to enhance the rate of tablet disintegration in the oral cavity, and are more appropriately termed fast-disintegrating tablets, as they may take up to a minute to completely disintegrate. This tablet format is designed to allow administration of an oral solid dose form in the absence of water or fluid intake. Such tablets readily dissolve or disintegrate in the saliva generally within &lt;60 seconds. Keywords: Mouth dissolving tablet, Disintegration, Patented technologies, Marketed MDTs Â

Development of orally disintegrating tablets of Perphenazine/hydroxypropyl-β-cyclodextrin inclusion complex

The aim of the present work was to prepare perphenazine (PPZ) orally disintegrating tablets (ODTs) based on the use of hydroxypropyl-β-cyclodextrin (HP-β-CD) forming inclusion complex with PPZ to improve the solubility and dissolution of this practically insoluble drug. Phase solubility studies were performed to evaluate the complexation of PPZ with HP-β-CD in three aqueous systems. The inclusion complex prepared by evaporation method was characterized by different physicochemical techniques, including the dissolution studies. The prepared complex was incorporated into ODTs containing different fillers and disintegrants. The ODTs prepared by direct compression were evaluated for drug content, hardness, porosity, friability, in vitro disintegration time (DT), wetting time (WT) and dissolution profiles. The solubility and dissolution rate were substantially improved compared with that of PPZ. Differential scanning calorimetry (DSC), X-ray powder diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) analyses suggested that PPZ could form true inclusion complex with HP-β-CD. The optimized formulation F6 exhibited short DT (15.5 ± 1.9 s) and WT (34.2 ± 2.3 s), sufficient hardness (30.4 ± 1.6 N/mm) and rapid drug dissolution. The developed tablet formulation could be a promising drug delivery system with improvements in PPZ bioavailability and patient compliance.

Contribution of the Physicochemical Properties of Active Pharmaceutical Ingredients to Tablet Properties Identified by Ensemble Artificial Neural Networks and Kohonen's Self-Organizing Maps

The aim of this study was to create a tablet database for use in designing tablet formulations. We focused on the contribution of active pharmaceutical ingredients (APIs) to tablet properties such as hardness and disintegration time (DT). Before we investigated the effects of the APIs, we optimized the tablet base formulation (placebo tablet) according to an expanded simplex search. The optimal placebo tablet showed sufficient hardness and rapid disintegration. We then tested 14 kinds of compounds as the model APIs. The APIs were characterized in terms of their physicochemical properties using Kohonen's self-organizing maps. We also prepared model tablets by incorporating the APIs into the optimal placebo tablet, and then examined the tablet properties, including tensile strength and DT. On the basis of the experimental data, an ensemble artificial neural network incorporating general regression analysis was conducted. A reliable model of the correlation between the physicochemical properties of the APIs and the tablet properties was thus constructed. From the correlation model, we clarified the detailed contributions of each physicochemical property to the tablet attributes.