Farming and processing factors for improving quality properties of poultry and rabbit meat

Recently, global meat market is facing several dramatic changes due to shifting in diet and life style, consumer demands, and economical considerations. Firstly, there was a tremendous increase in the poultry meat demand. Furthermore, current forecast and projection studies pointed out that the expansion of the poultry market will continue in future. In response to this demand, there was a great success to increase growth rate of meat-type chickens in the last few decades in order to optimize the production of poultry meat. Accordingly, the increase of growth rate induced the appearance of several muscle abnormalities such as pale-soft-exudative (PSE) syndrome and deep-pectoral-myopathy (DPM) and more recently white striping and wooden breast. Currently, there is growing interest in meat industry to understand how much the magnitude of the effect of these abnormalities on different quality traits for raw and processed meat. Therefore, the major part of the research activities during the PhD project was dedicated to evaluate the different implications of recent muscle abnormalities such as white striping and wooden breast on meat quality traits and their incidence under commercial conditions. Generally, our results showed that the incidence of these muscle abnormalities was very high under commercial conditions and had great adverse impact on meat quality traits. Secondly, there is growing market share of convenient, healthy, and functional processed meat products. Accordingly, the remaining part of research activities of the PhD project was dedicated to evaluate the possibility to formulate processed meat products with higher perceived healthy profile such as phosphate free-marinated chicken meat and low sodium-marinated rabbit meat products. Overall all findings showed that sodium bicarbonate can be considered as promising component to replace phosphates in meat products, while potassium chloride under certain conditions was successfully used to produce low marinated rabbit meat products.

Removal of enamel caries with an air abrasion powder

This study compared the efficiency of air abrasion on enamel caries with selective enamel powder (SEP) or with alumina powder and a negative and positive control group. Ninety-three extracted molars with non-cavitated incipient enamel lesions were selected. After embedding the roots in resin, each lesion was sectioned perpendicular to the surface and photographed. Each lesion was classified microscopically as having or not having dentin involvement. The lesions were distributed into four groups with an equal number of enamel caries with or without dentin involvement. Each group was treated differently: Group 1 had SEP abrasion, Group 2 had alumina abrasion, Group 3 had sodium bicarbonate abrasion (negative control) and Group 4 had bur treatment (positive control). The surface was rephotographed after treatment. Superimposition of the photographs identified areas of "correct-excavation," "under-excavation" and "over-excavation." There were no statistical differences between lesions treated with or without dentin involvement for Groups 2 through 4. However, in the SEP group, all measured areas were significantly influenced by dentin involvement. In pairwise comparisons, no statistical differences were found between the alumina and bur groups. The SEP group, however, showed statistically significant differences for each area compared to the alumina group in enamel caries without dentin involvement. SEP performed as well as alumina and bur in lesions with dentin involvement. SEP is different in its ablative properties toward caries with dentin involvement or no dentin involvement. In terms of dental treatment, SEP seems to have a diagnostic potential for enamel lesions before operative intervention in patients with high caries risk.

Influence of different professional prophylactic methods on fluorescence measurements for detection of occlusal caries

This study aimed to evaluate the influence of professional prophylactic methods on the DIAGNOdent 2095, DIAGNOdent 2190 and VistaProof performance in detecting occlusal caries. Assessments were performed in 110 permanent teeth at baseline and after bicarbonate jet or prophylactic paste and rinsing. Performance in terms of sensitivity improved after rinsing of the occlusal surfaces when the prophylactic paste was used. However, the sodium bicarbonate jet did not significantly influence the performance of the fluorescence-based methods. It can be concluded that different professional prophylactic methods can significantly influence the performance of fluorescence-based methods for occlusal caries detection.

Evaluation of Proteferm® as a Nitrogen Supplement for Finishing Steers

Proteferm is a liquid by-product from the production of monosodium glutamate by fermentation that is 40% solids and contains 95% crude protein on a dry basis. Two trials were conducted with yearling steers to study the effects of different levels of Proteferm when added to 90% concentrate diets to replace corn and urea. Feeding Proteferm resulted in a decrease in urine pH, suggesting a metabolic acidosis that was probably caused by a negative cation–anion balance. Correcting the cation–anion imbalance resulted in an increase in feed intake and the performance of steers fed Proteferm as 1.5% of diet dry matter to be similar to the performance of control steers. Addition of sodium bicarbonate to the control diet or to the diet containing 1.5% Proteferm to produce a positive cation–anion balance did not improve performance. The results of these trials indicate that 1.5% Proteferm is the maximum that should be added to high concentrate diets fed to beef cattle without affecting performance or carcass value.

Candidate gene identification following linkage: Search for hypertension susceptibility genes

Following up genetic linkage studies to identify the underlying susceptibility gene(s) for complex disease traits is an arduous yet biologically and clinically important task. Complex traits, such as hypertension, are considered polygenic with many genes influencing risk, each with small effects. Chromosome 2 has been consistently identified as a genomic region with genetic linkage evidence suggesting that one or more loci contribute to blood pressure levels and hypertension status. Using combined positional candidate gene methods, the Family Blood Pressure Program has concentrated efforts in investigating this region of chromosome 2 in an effort to identify underlying candidate hypertension susceptibility gene(s). Initial informatics efforts identified the boundaries of the region and the known genes within it. A total of 82 polymorphic sites in eight positional candidate genes were genotyped in a large hypothesis-generating sample consisting of 1640 African Americans, 1339 whites, and 1616 Mexican Americans. To adjust for multiple comparisons, resampling-based false discovery adjustment was applied, extending traditional resampling methods to sibship samples. Following this adjustment for multiple comparisons, SLC4A5, a sodium bicarbonate transporter, was identified as a primary candidate gene for hypertension. Polymorphisms in SLC4A5 were subsequently genotyped and analyzed for validation in two populations of African Americans (N = 461; N = 778) and two of whites (N = 550; N = 967). Again, SNPs within SLC4A5 were significantly associated with blood pressure levels and hypertension status. While not identifying a single causal DNA sequence variation that is significantly associated with blood pressure levels and hypertension status across all samples, the results further implicate SLC4A5 as a candidate hypertension susceptibility gene, validating previous evidence for one or more genes on chromosome 2 that influence hypertension related phenotypes in the population-at-large. The methodology and results reported provide a case study of one approach for following up the results of genetic linkage analyses to identify genes influencing complex traits. ^

Collection of data on particulate and dissolved soil phosphorus in the Jena Experiment (Main Experiment, time series since 2002)

This data set contains two time series of measurements of dissolved phosphorus (organic, inorganic and total with a biweekly resolution) and dissolved inorganic phosphorus with a seasonal resolution. In addition, data on phosphorus from soil samples measured in 2007 and fractionated by different acid-extrations (Hedley fractions) are provided. All data measured at the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. 1. Dissolved phosphorus in soil solution: Suction plates installed on the field site in 10, 20, 30 and 60 cm depth were used to sample soil pore water. Cumulatively extracted soil solution was collected every two weeks from October 2002 to May 2006. The biweekly samples from 2002, 2003 and 2004 were analyzed for dissolved organic phosphorus (DOP), dissolved inorganic phosphorus (PO4P) and dissolved total phosphorus (TDP) by Continuous Flow Analyzer (CFA SAN ++, SKALAR [Breda, The Netherlands]). 2. Seasonal values of dissolved inorganic phosphorus in soil solution were calculated as volume-weighted mean values of the biweekly measurements (spring = March to May, summer = June to August, fall = September to November, winter = December to February). 3. Phosphorus fractions in soil: Five independent soil samples per plot were taken in a depth of 0-15 cm using a soil corer with an inner diameter of 1 cm. The five samples per plot were combined to one composite sample per plot. A four-step sequential P fractionation (Hedley fractions) was applied and concentrations of P fractions in soil were measured photometrically (molybdenum blue-reactive P) with a Continuous Flow Analyzer (Bran&Luebbe, Germany).

Phosphorus fractions in soil of the Jena Experiment (Main Experiment, year 2007)

This data set contains measurements of phosphorus fractions (Hedley fractions) in soil collected 2007 from the main experiment plots of a large grassland biodiversity experiment (the Jena Experiment; see further details below). In the main experiment, 82 grassland plots of 20 x 20 m were established from a pool of 60 species belonging to four functional groups (grasses, legumes, tall and small herbs). In May 2002, varying numbers of plant species from this species pool were sown into the plots to create a gradient of plant species richness (1, 2, 4, 8, 16 and 60 species) and functional richness (1, 2, 3, 4 functional groups). Plots were maintained by bi-annual weeding and mowing. Soil sampling and analysis: Five independent soil samples per plot were taken in a depth of 0-15 cm using a soil corer with an inner diameter of 1 cm. The five samples per plot were combined to one composite sample per plot. A four-step sequential P fractionation (Hedley fractions) was applied. Sequentially, 20 ml NaHCO3 (adjusted to pH 8.5), 30 ml NaOH, and 35 ml HCl were used as extraction solutions for 0.5 g soil. The last step comprised the combustion (550 °C) of the remaining soil to destroy all organic material followed by shaking with 20 ml H2SO4. Organic P concentrations of the respective fractions were calculated as the difference between total dissolved P and inorganic P. Duplicate phosphate concentrations of P fractions in soil were measured photometrically (molybdenum blue-reactive P) with a Continuous Flow Analyzer (Bran&Luebbe, Germany).

Phototrophic carbon fixation rates measured in water samples from the Porcupine Abyssal Plains during James Cook cruise JC087

Water samples were collected from pre-dawn CTD casts at 5 depths corresponding to 55%, 20%, 7%, 5% and 1% of surface irradiance. 1 litre water samples wrapped with optical filters to replicate light levels. Spiked with 200 µL of 13C labelled sodium bicarbonate. After 24 hourse filtered through ashed 25mm GF/F (Whatman) filters, rinsed with HCl solution (1-2%) and stored at -20oC. On shore encapsulated in tin capsules and analysed for 13C isotopic enrichment. Carbon uptake rates calculated using the equations of Fernandez et al. (2005).

Carbon uptake rate calculated for melt pond water samples during POLARSTERN cruise ARK-XXVII/3 (IceArc) in 2012

Net Primary Production was measured using the 14**C uptake method with minor modifications. Melt pond samples were spiked with 0.1µCi ml**-1 of 14**C labelled sodium bicarbonate (Moravek Biochemicals, Brea, USA) and distributed in 10 clear bottles (20 ml each). Subsequently they were incubated for 12 h at -1.3°C under different scalar irradiances (0-420 µmol photons m**-2 s**-1) measured with a spherical sensor (Spherical Micro Quantum Sensor US-SQS/L, Heinz Walz, Effeltrich, Germany). At the end of the incubation, samples were filtered onto 0.2 µm nitrocellulose filters and the particulate radioactive carbon uptake was determined by liquid scintillation counting using Filter count scintillation cocktail (Perkin Elmer, Waltham, USA). The carbon uptake values in the dark were subtracted from the carbon uptake values measured in the light incubations. Dissolved inorganic carbon (DIC) was measured for each sample using the flow injection system (Hall and Aller, 1992). The DIC concentration was taken into account to calculate the amount of labeled bicarbonate incorporated into the cell. Carbon fixation rates were normalized volumetrically and by chlorophyll a. Photosynthesis-irradiance curves (PI curves) were fitted using MATLAB® according to the equation proposed by Platt et al. (1980) including a photoinhibition parameter (beta) and providing the main photosynthetic parameters: maximum Chla normalized carbon fixation rate if there were no photoinhibition (Pb) and the initial slope of the saturation curve (alpha). The derived parameters: light intensity at which photosynthesis is maximal (Im), the carbon fixation rate at that maximal irradiance (Pbm) and the adaptation parameter or photoacclimation index (Ik) were calculated according to Platt et al. (1982).

Carbon uptake rate calculated for CTD water samples during POLARSTERN cruise ARK-XXVII/3 (IceArc) in 2012

Net Primary Production was measured using the 14**C uptake method with minor modifications. Seawater samples were spiked with 0.1µCi ml**-1 of 14**C labelled sodium bicarbonate (Moravek Biochemicals, Brea, USA) and distributed in 10 clear bottles (20 ml each). Subsequently they were incubated for 12 h at -1.3°C under different scalar irradiances (0-420 µmol photons m**-2 s**-1) measured with a spherical sensor (Spherical Micro Quantum Sensor US-SQS/L, Heinz Walz, Effeltrich, Germany). At the end of the incubation, samples were filtered onto 0.2 µm nitrocellulose filters and the particulate radioactive carbon uptake was determined by liquid scintillation counting using Filter count scintillation cocktail (Perkin Elmer, Waltham, USA). The carbon uptake values in the dark were subtracted from the carbon uptake values measured in the light incubations. Dissolved inorganic carbon (DIC) was measured for each sample using the flow injection system (Hall and Aller, 1992). The DIC concentration was taken into account to calculate the amount of labeled bicarbonate incorporated into the cell. Carbon fixation rates were normalized volumetrically and by chlorophyll a. Photosynthesis-irradiance curves (PI curves) were fitted using MATLAB® according to the equation proposed by Platt et al. (1980) including a photoinhibition parameter (beta) and providing the main photosynthetic parameters: maximum Chla normalized carbon fixation rate if there were no photoinhibition (Pb) and the initial slope of the saturation curve (alpha). The derived parameters: light intensity at which photosynthesis is maximal (Im), the carbon fixation rate at that maximal irradiance (Pbm) and the adaptation parameter or photoacclimation index (Ik) were calculated according to Platt et al. (1982).

Villefranche sur Mer: multistressors experiment March 2012

The effect of ocean warming and acidification was investigated on a natural plankton assemblage from an oligotrophic area, the bay of Villefranche (NW Mediterranean Sea). The assemblage was sampled in March 2012 and exposed to the following four treatments for 12 days: control ( 360 µatm, 14°C), elevated pCO2 ( 610 µatm, 14°C), elevated temperature ( 410 µatm, 17°C), and elevated pCO2 and temperature ( 690 µatm, 17°C). Nutrients were already depleted at the beginning of the experiment and the concentrations of chlorophyll a (chl a), heterotrophic prokaryotes and viruses decreased, under all treatments, throughout the experiment. There were no statistically significant effects of ocean warming and acidification, whether in isolation or combined, on the concentrations of nutrients, particulate organic matter, chl a and most of the photosynthetic pigments. Furthermore, 13C labelling showed that the carbon transfer rates from 13C-sodium bicarbonate into particulate organic carbon were not affected by seawater warming nor acidification. Rates of gross primary production followed the general decreasing trend of chl a concentrations and were significantly higher under elevated temperature, an effect exacerbated when combined to elevated pCO2 level. In contrast to the other algal groups, the picophytoplankton population (cyanobacteria, mostly Synechococcus) increased throughout the experiment and was more abundant in the warmer treatment though to a lesser extent when combined to high pCO2 level. These results suggest that under nutrient-depleted conditions in the Mediterranean Sea, ocean acidification has a very limited impact on the plankton community and that small species will benefit from warming with a potential decrease of the export and energy transfer to higher trophic levels.

Carbon uptake rate calculated for sea-ice core samples during POLARSTERN cruise ARK-XXVII/3 (IceArc) in 2012

Net Primary Production was measured using the 14**C uptake method with minor modifications. Melted sea ice samples were spiked with 0.1µCi ml**-1 of 14**C labelled sodium bicarbonate (Moravek Biochemicals, Brea, USA) and distributed in 10 clear bottles (20 ml each). Subsequently they were incubated for 12 h at -1.3°C under different scalar irradiances (0-420 µmol photons m**-2 s**-1) measured with a spherical sensor (Spherical Micro Quantum Sensor US-SQS/L, Heinz Walz, Effeltrich, Germany). At the end of the incubation, samples were filtered onto 0.2 µm nitrocellulose filters and the particulate radioactive carbon uptake was determined by liquid scintillation counting using Filter count scintillation cocktail (Perkin Elmer, Waltham, USA). The carbon uptake values in the dark were subtracted from the carbon uptake values measured in the light incubations. Dissolved inorganic carbon (DIC) was measured for each sample using the flow injection system (Hall and Aller, 1992). The DIC concentration was taken into account to calculate the amount of labeled bicarbonate incorporated into the cell. Carbon fixation rates were normalized volumetrically and by chlorophyll a. Photosynthesis-irradiance curves (PI curves) were fitted using MATLAB® according to the equation proposed by Platt et al. (1980) including a photoinhibition parameter (beta) and providing the main photosynthetic parameters: maximum Chla normalized carbon fixation rate if there were no photoinhibition (Pb) and the initial slope of the saturation curve (alpha). The derived parameters: light intensity at which photosynthesis is maximal (Im), the carbon fixation rate at that maximal irradiance (Pbm) and the adaptation parameter or photoacclimation index (Ik) were calculated according to Platt et al. (1982).

Bicarbonato ingestion has no ergogenic effect on consecutive all out sprint test in MWX elite cyclists

The aim of the present study was to examine the effect of sodium bicarbonate ingestion on consecutive "all out" sprint tests, analyzing the acid-base status and its influence on performance and perceived effort. Ten elite bicycle motocross (BMX) riders (20.7 ± 1.4 years, training experience 8-12 years) participated in this study which consisted of two trials. Each trial consisted of three consecutive Wingate tests (WTs) separated by 15 min recovery. Ninety minutes prior to exercise subjects ingested either NaHCO(3) (-) (0.3 g kg(-1) body weight) or placebo. Blood samples were collected for the assessment of blood acid-base status: bicarbonate concentration ([HCO(3) (-)]), pH, base excess (BE) and blood lactate concentration ([La(-)]). Performance variables of peak power (PP), mean power (MP), time to peak power and fatigue index were calculated for each sprint. Significant differences (p < 0.05) were observed in acid-base variables [pH before WT1: 7.47 ± 0.05 vs. 7.41 ± 0.03; [HCO(3) (-)] before WT1: 29.08 ± 2.27 vs. 22.85 ± 0.24 mmol L(-1) (bicarbonate vs. placebo conditions, respectively)], but there were not significant differences in performance variables between trials [PP WT1: 1,610 ± 373 vs. 1,599 ± 370 W; PP WT2: 1,548 ± 460 vs. 1,570 ± 428 W; PP WT3: 1,463 ± 361 vs. 1,519 ± 364 W. MP WT1: 809 ± 113 vs. 812 ± 108 W; MP WT2: 799 ± 135 vs. 799 ± 124 W; MP WT3: 762 ± 165 vs. 782 ± 118 W (bicarbonate vs. placebo conditions, respectively)]. Rating of perceived effort (RPE) was not influenced nor ratings of perceived readiness. Sodium bicarbonate ingestion modified significantly the blood acid-base balance, although the induced alkalosis did not improve the Wingate test performance, RPE and perceived readiness across three consecutive WTs in elite BMX cyclists.

Desarrollo de conglomerados con la incorporación de cenizas volantes procedentes de la incineración de residuos sólidos urbanos

Esta tesis presenta los resultados de la investigación realizada sobre la inertización de cenizas volantes procedentes de residuos sólidos urbanos y su posterior encapsulación en distintas matrices de mortero. Durante el proceso de inertización, se ha logrado la inertización de éste residuo tóxico y peligroso (RTP) y también su valorización como subproducto. De esta forma se dispone de nueva “materia prima” a bajo coste y la eliminación de un residuo tóxico y peligroso con la consiguiente conservación de recursos naturales alternativos. La caracterización química de las cenizas analizadas refleja que éstas presentan altas concentraciones de cloruros, Zn y Pb. Durante la investigación se ha desarrollado un proceso de inertización de las cenizas volantes con bicarbonato sódico (NaHCO3) que reduce en un 99% el contenido en cloruros y mantiene el pH en valores óptimos para que la concentración de los metales pesados en el lixiviado sea mínima debido a su estabilización en forma de carbonatos insolubles. Se han elaborado morteros con cuatro tipos distintos de cementos (CEM-I, CEM-II, CAC y CSA) incorporando cenizas volantes inertizadas en una proporción igual a un 10% en peso del árido utilizado. Los morteros ensayados abarcan distintas dosificaciones tanto en la utilización de áridos con distintos diámetros (0/2 y 0/4), como en la relación cemento/árido (1/1 y 1/3). Se han obtenido las propiedades físicas y mecánicas de estos morteros mediante ensayos de Trabajabilidad, Estabilidad Dimensional, Carbonatación, Porosidad y Resistencias Mecánicas. De igual forma, se presentan resultados de ensayos de lixiviación de Zn, Pb, Cu y Cd, sobre probetas monolíticas de los morteros con los mejores comportamientos físico/mecánicos, donde se ha analizado el contenido en iones de dichos metales pesados lixiviados mediante determinación voltamperométrica de redisolución anódica Se concluye que todos los morteros ensayados son técnicamente aceptables, siendo los más favorables los elaborados con Cemento de Sulfoaluminato de Calcio (CSA) y con Cemento de Aluminato de Calcio (CAC). En este último caso, se mejoran las resistencias a compresión de los morteros de referencia en más de un 48%, y las resistencias a flexión en más de un 67%. De igual forma, los ensayos de lixiviado revelan la completa encapsulación de los iones de Zn y la mitigación en el lixiviado de los iones de Pb. Ambos morteros podrían ser perfectamente validos en actuaciones en las que se necesitase un producto de fraguado rápido, altas resistencias iniciales y compensación de las retracciones con una elevada estabilidad dimensional. En base a esto, el material podría ser utilizado como mortero de reparación en viales y pavimentos que requiriesen altas prestaciones, tales como: soleras industriales, pistas de aterrizaje, aparcamientos, etc. O bien, para la confección de elementos prefabricados sin armaduras estructurales, dada su elevada resistencia a flexión. ABSTRACT This dissertation presents the results of a research on inerting fly ash from urban solid waste and its subsequent encapsulation in mortar matrixes. The inerting of this hazardous toxic waste, as well as its valorization as a by-product has been achieved. In this way, a new "raw material" is available through a simple process and the toxic and hazardous waste is eliminated, and consequently, conservation of alternative natural resources is strengthened. Chemical analysis of the ashes analyzed shows high concentrations of soluble chlorides, Zn and Pb. An inerting process of fly ash with sodium bicarbonate (NaHCO3) has been developed which reduces 99% the content of chlorides and maintains pH at optimal values, so that the concentration of heavy metals in the leachate is minimum, due to its stabilization in the form of insoluble carbonates. Mortars with four different types of cements (CEM-I, CEM-II, CAC and CSA) have been developed by the addition of inertized fly ash in the form of carbonates, in the proportion of 10% in weight of the aggregates used. The samples tested include different proportions in the use of aggregates with different sizes (0/2 and 0/4), and in the cement/aggregate ratio (1/1 and 1/3). Physical/mechanical properties of these mortars have been studied through workability, dimensional stability, carbonation, porosity and mechanic strength tests. Leaching tests of Zn, Pb, Cu and Cd ions are also being performed on monolithic samples of the best behavioral mortars. The content in leachated heavy metal ions is being analyzed through stripping voltammetry determination. Conclusions drawn are that the tested CAC and CSA cement mortars present much better behavior than those of CEM-I and CEM-II cement. The results are especially remarkable for the CAC cement mortars, improving reference mortars compression strengths in more than 48%, and also bending strengths in more than 67%. Leaching tests confirm that the encapsulation of Zn and Pb is achieved and leachate of both ions is mitigated within the mortar matrixes. For the above stated reasons, it might be concluded that mortars made with calcium aluminate cements or calcium sulfoaluminate with the incorporation of treated fly ash, may be perfectly valid for uses in which a fast-curing product, with high initial strength and drying shrinkage compensation with a high dimensional stability is required. Based on this, the material could be used as repair mortar for structures, roads and industrial pavements requiring high performance, such as: industrial floorings, landing tracks, parking lots, etc. Alternatively, it could also be used in the manufacture of prefabricated elements without structural reinforcement, given its high bending strength.

The effect of selected water-soluble excipients on the dissolution of paracetamol and ibuprofen

The purpose of this investigation was to study the dissolution behavior of paracetamol and ibuprofen in the presence of a range of selected potential excipients. First, a pH-solubility profile was generated for both drugs, and the effect of changing hydrodynamic conditions on the intrinsic dissolution rate was investigated. It was established that both drugs dissolved according to the diffusion-layer model. Paracetamol solubility (approximately 20.3 mg mL -1) did not vary from pH 1.2-8.0, corresponding to the in vivo range in the gastrointestinal tract. Ibuprofen had an intrinsic solubility of approximately 0.06 mg mL-1, and pKa was calculated as 4.4. Second, the effects of selected potential excipients (lactose, potassium bicarbonate, sodium bicarbonate, sodium chloride, and tartaric acid) were evaluated by measuring the effect of the inclusion of each additive in the dissolution medium on drug solubility, drug intrinsic dissolution rate, and solution viscosity. The results were evaluated using the diffusion-layer model, and it was determined that for paracetamol, the collected data fitted the model for all the excipients studied. For ibuprofen, it was found that there were differences between the excipients that raised the solution pH above the pK a to those that did not. For the excipients raising the pH above the pKa, the effect on intrinsic dissolution rate was not as high as that expected from the change in drug solubility. It was postulated that this might be due to lack of penetration of the excipient into the drug boundary layer microenvironment. Formulators may calculate the effect of adding an excipient based on solubility increases but may not find the dissolution rate improvement expected. Copyright © 2005 Taylor & Francis Inc.