O extrato bruto (DCM:MeOH 2:1) das raízes de Piper crassinervium foi submetido a fracionamentos cromatográficos resultando no isolamento e identificação de oito substâncias, sendo estas uma flavanona (5,4\'-diidroxi-7-metoxiflavanona [isosakuranetina]), duas hidroquinonas preniladas (1,4-diidroxi-2-[3\',7\'-dimetil-1\'-oxo-2\'-E-6\'-octadienil]-benzeno e 1,4-diidroxi-2-[3\',7\'-dimetil-1\'-oxo-2\'-Z-6\'-octadienil]-benzeno), um cromeno (ácido-2-metil-2-[4\'-metil-3\'-pentenil]2H-1-benzopirano-6-carboxílico), um derivado prenilado do ácido benzóico (ácido 4-hidroxi-3-[3\',7\'-dimetil-1\'-oxo-octa-2\'-E-6\'-dienil]-benzóico), uma amida isobutílica (piperlonguminina) e duas amidas piperidínicas (piperina e diidropiperina). As substâncias isoladas tiveram suas estruturas químicas determinadas por experimentos de espectrometria de massas, RMN de 1H e 13C e comparadas com os dados da literatura. / The crude extracts of the roots of Piper crassinervium was submitted to chromatographic steps yielding eight compounds including a flavanone (5,4\'-dihydroxy-7-methoxyflavanone [isosakuranetin]), two prenylated hydroquinones (1,4-dihydroxy-2-[3\',7\'-dimethyl-1\'-oxo-2\'-E-6\'-octadienyl]-benzene and 1,4-dihydroxy-2-[3\',7\'-dimethyl-1\'-oxo-2\'-Z-6\'-octadienyl]-benzene), one chromene (2-methyl-2-[4\'-methyl-3\'-pentenyl]-2H-1-benzopyran-6-carboxylic acid), one prenylated derivative of benzoic acid (4-hydroxy-3-[3\',7\'-dimethil-1\'-oxo]2\'-E-6\'-octadienyl-benzoic acid), one isobutyl amide (piperlonguminine) and two piperidine amides (piperine and dihydropiperine). The structures of the isolated compounds were determined by mass spectrometry, 1H and 13C NMR data by comparison with the literature data.

Semi-batch crystallization experiments have been performedboth in a loop reactor and in stirred tank reactors.Hydrochloric acid was fed to a stirred solution of sodiumbenzoate, and benzoic acid immediately formed. Benzoic acid isformed in excess of the solubility making the solutionsupersaturated. The loop reactor is U-shaped. In one leg a propeller stirrerwas placed to circulate the solution and in the other a turbinestirrer was placed in front of the feed point to vary the localmixing intensity. The objective was to analyse the relativeimportance of different levels of mixing on the product sizedistribution. The importance of mixing as well as scaling-upeffects on the product size distribution were studied in threestirred tank reactors of volumes 2.5 L, 10 L, and 200 L. Thestirred tank reactors had different geometry and were equippedwith either a marine propeller or a pitched blade turbine. The weight mean size generally increases with increasingtotal feeding time and increasing mixing intensity. The weightmean size increases by locating an extra turbine impeller atthe feed point in the 10 L stirred tank reactor. The turbineimpeller provides the desired feed point mixing intensitywithout raising the mixing intensity of the whole tank. The weight mean size increases with decreasing feed pipediameter in the loop reactor and for low feed rates in the 10 Lstirred tank reactor. The weight mean size increasessignificantly by changing the feed pipe opening from circularto rectangular with a constant cross-sectional area at equalfeed rates. Backmixing is visually observed in the largest feedpipe diameter in the loop reactor, thus, reducing the weightmean size. However, backmixing is not considered to be adominant phenomenon in the present work. Mesomixing time constants have been calculated according tothe turbulent dispersion mechanism and the inertial-convectivemechanism. The time constants for mesomixing are generallylonger than the time constant for micromixing. Thus, the ratioof the mesomixing and the micromixing time constants shows aninfluence of mesomixing as is shown by the experimentalresults. The experimental results are best described by theinertial-convective disintegration mechanism showing that thefeed plume mixing increases with decreasing feed pipe diameterand increased feed point mixing. The weight mean size is not strongly affected by the reactorvolume. However, the mixing conditions in the reactors have astrong influence on the weight mean size. No suggestedscaling-up rule can satisfactorily predict the weight mean sizein the different volumes. No single physical parameter, such asthe local energy dissipation rate, the mean energy dissipationrate or the circulation time, can satisfactorily explain theexperimental results. A new dimensionless mixing parameter, TR,has been defined as the ratio of the total feeding time and themesomixing time constant. The mesomixing time constant isdefined as the shortest dimension of the feed pipe divided bythe resultant bulk velocity passing the feed pipe entrance. Theexperimental results from both the loop reactor and the stirredtank reactors of different volumes can be correlated with TR.The weight mean size increases with increasing TR. <b>Keywords</b>: reaction crystallization, precipitation,benzoic acid, macromixing, mesomixing, micromixing,semi-batch, loop reactor, backmixing, colour experiments,scaling-up. <b>Keywords</b>: reaction crystallization, precipitation,benzoic acid, macromixing, mesomixing, micromixing,semi-batch, loop reactor, backmixing, colour experiments,scaling-up.

<p>Semi-batch crystallization experiments have been performedboth in a loop reactor and in stirred tank reactors.Hydrochloric acid was fed to a stirred solution of sodiumbenzoate, and benzoic acid immediately formed. Benzoic acid isformed in excess of the solubility making the solutionsupersaturated.</p><p>The loop reactor is U-shaped. In one leg a propeller stirrerwas placed to circulate the solution and in the other a turbinestirrer was placed in front of the feed point to vary the localmixing intensity. The objective was to analyse the relativeimportance of different levels of mixing on the product sizedistribution. The importance of mixing as well as scaling-upeffects on the product size distribution were studied in threestirred tank reactors of volumes 2.5 L, 10 L, and 200 L. Thestirred tank reactors had different geometry and were equippedwith either a marine propeller or a pitched blade turbine.</p><p>The weight mean size generally increases with increasingtotal feeding time and increasing mixing intensity. The weightmean size increases by locating an extra turbine impeller atthe feed point in the 10 L stirred tank reactor. The turbineimpeller provides the desired feed point mixing intensitywithout raising the mixing intensity of the whole tank.</p><p>The weight mean size increases with decreasing feed pipediameter in the loop reactor and for low feed rates in the 10 Lstirred tank reactor. The weight mean size increasessignificantly by changing the feed pipe opening from circularto rectangular with a constant cross-sectional area at equalfeed rates. Backmixing is visually observed in the largest feedpipe diameter in the loop reactor, thus, reducing the weightmean size. However, backmixing is not considered to be adominant phenomenon in the present work.</p><p>Mesomixing time constants have been calculated according tothe turbulent dispersion mechanism and the inertial-convectivemechanism. The time constants for mesomixing are generallylonger than the time constant for micromixing. Thus, the ratioof the mesomixing and the micromixing time constants shows aninfluence of mesomixing as is shown by the experimentalresults. The experimental results are best described by theinertial-convective disintegration mechanism showing that thefeed plume mixing increases with decreasing feed pipe diameterand increased feed point mixing.</p><p>The weight mean size is not strongly affected by the reactorvolume. However, the mixing conditions in the reactors have astrong influence on the weight mean size. No suggestedscaling-up rule can satisfactorily predict the weight mean sizein the different volumes. No single physical parameter, such asthe local energy dissipation rate, the mean energy dissipationrate or the circulation time, can satisfactorily explain theexperimental results. A new dimensionless mixing parameter, TR,has been defined as the ratio of the total feeding time and themesomixing time constant. The mesomixing time constant isdefined as the shortest dimension of the feed pipe divided bythe resultant bulk velocity passing the feed pipe entrance. Theexperimental results from both the loop reactor and the stirredtank reactors of different volumes can be correlated with TR.The weight mean size increases with increasing TR.</p><p><b>Keywords</b>: reaction crystallization, precipitation,benzoic acid, macromixing, mesomixing, micromixing,semi-batch, loop reactor, backmixing, colour experiments,scaling-up.</p><p><b>Keywords</b>: reaction crystallization, precipitation,benzoic acid, macromixing, mesomixing, micromixing,semi-batch, loop reactor, backmixing, colour experiments,scaling-up.</p>

O extrato bruto (DCM:MeOH 2:1) das raízes de Piper crassinervium foi submetido a fracionamentos cromatográficos resultando no isolamento e identificação de oito substâncias, sendo estas uma flavanona (5,4\'-diidroxi-7-metoxiflavanona [isosakuranetina]), duas hidroquinonas preniladas (1,4-diidroxi-2-[3\',7\'-dimetil-1\'-oxo-2\'-E-6\'-octadienil]-benzeno e 1,4-diidroxi-2-[3\',7\'-dimetil-1\'-oxo-2\'-Z-6\'-octadienil]-benzeno), um cromeno (ácido-2-metil-2-[4\'-metil-3\'-pentenil]2H-1-benzopirano-6-carboxílico), um derivado prenilado do ácido benzóico (ácido 4-hidroxi-3-[3\',7\'-dimetil-1\'-oxo-octa-2\'-E-6\'-dienil]-benzóico), uma amida isobutílica (piperlonguminina) e duas amidas piperidínicas (piperina e diidropiperina). As substâncias isoladas tiveram suas estruturas químicas determinadas por experimentos de espectrometria de massas, RMN de 1H e 13C e comparadas com os dados da literatura. / The crude extracts of the roots of Piper crassinervium was submitted to chromatographic steps yielding eight compounds including a flavanone (5,4\'-dihydroxy-7-methoxyflavanone [isosakuranetin]), two prenylated hydroquinones (1,4-dihydroxy-2-[3\',7\'-dimethyl-1\'-oxo-2\'-E-6\'-octadienyl]-benzene and 1,4-dihydroxy-2-[3\',7\'-dimethyl-1\'-oxo-2\'-Z-6\'-octadienyl]-benzene), one chromene (2-methyl-2-[4\'-methyl-3\'-pentenyl]-2H-1-benzopyran-6-carboxylic acid), one prenylated derivative of benzoic acid (4-hydroxy-3-[3\',7\'-dimethil-1\'-oxo]2\'-E-6\'-octadienyl-benzoic acid), one isobutyl amide (piperlonguminine) and two piperidine amides (piperine and dihydropiperine). The structures of the isolated compounds were determined by mass spectrometry, 1H and 13C NMR data by comparison with the literature data.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this dissertation was to evaluate the performance of lactating sows and their piglets fed with high moisture corn diets with or without acidifiers. Fifteen sows of commercial genetic lines were used in a randomized complete block with three treatments (negative control diet elaborated each 24h; control diet with 0.5% of benzoic acid elaborated each 24h; control diet with 0.5% of fumaric acid elaborated each 24h) with five replications each. Diets elaborated with high moisture corn with benzoic or fumaric acids did not modify (P>0.05) the backfat thickness. The average daily feed intake (7.93kg/NM) of lactating sows was not influenced (P>0.05) by treatments. The average daily weight gain (0.22kg) and average weaning live weight (6.2kg) of piglets were not influenced (P>0.05) by diets with benzoic or fumaric acids. The addition of fumaric acid in diets of lactation sows decreased (P<0.05) the liquid feces frequency in piglets comparated with negative control diet. The addition of acidifiers in diets containing high moisture corn does not alter performance of lactating sows neither their piglets. / O objetivo desta dissertação foi avaliar o desempenho de porcas lactantes e suas leitegadas alimentadas com dietas contendo silagem de grãos úmidos de milho com ou sem acidificantes. Foram utilizadas quinze porcas de genética comercial em um delineamento de blocos ao acaso com três tratamentos (dieta controle negativo elaborada a cada 24h; dieta com adição de 0,5% de ácido benzóico elaborada a cada 24h e dieta com adição de 0,5% de ácido fumárico elaborada a cada 24h) com cinco repetições cada. As dietas elaboradas com silagem de grãos úmidos de milho com ácidos benzóico ou fumárico não alteraram (P>0,05) a espessura de toicinho. O consumo diário de alimento das porcas lactantes foi de 7,93kg/MN não variando (P>0,05) entre os tratamentos. O ganho médio diário de peso dos leitões foi de 0,22kg, não variando (P>0,05) entre os tratamentos. O peso vivo médio dos leitões ao desmame foi de 6,2kg não diferindo (P>0,05) entre leitões de porcas lactantes alimentadas com dietas com ácido benzóico ou fumárico. No período total de 21 dias, a adição de ácido fumárico na dieta de porcas lactantes diminuiu em 30% (P<0,05) a freqüência de fezes líquidas dos leitões em relação à dieta controle. A adição de ácidos fumárico e benzóico em dietas elaboradas com silagem de grãos úmidos de milho não alteram os desempenhos de porcas lactantes e nem o de suas leitegadas.

Syngeneic graft-versus-host disease (SGVHD) is induced by reconstituting lethally irradiated mice with syngeneic BM cells followed by a 21 day treatment with the immunosuppressive agent cyclosporine A (CsA). Clinical symptoms of the disease appear 2-3 weeks following cessation of CsA therapy and disease-associated inflammation occurs primarily in the colon and liver. The development of SGVHD is a complex process resulting from the cooperative interaction of multiple effector cell populations including NK cells, T cells and macrophages. TH1 cytokines (IL-12, TNF-α, IFN- γ), produced by these effector cells, serve as inflammatory mediators contributing to the pathogenesis of SGVHD. The SGVHD conditioning agents, irradiation and CsA, are both required for the development of disease and contribute to the production of oxidative stress. Time course studies revealed increased reactive oxygen and nitrogen species (ROS/RNS), as well as, increased colon mRNA levels for TNF-α and iNOS in CsA-treated versus control BMT animals. Since ROS/RNS are known to mediate CsA toxicity, studies were undertaken to determine the effect of oxidative stress on the induction of SGVHD. In vivo treatment with the antioxidant MnTBAP caused a reduction in colon mRNA levels for iNOS and TNF-α, as well as delayed disease development, suggesting a role for oxidative stress in the development of SGVHD. In addition, CD4+ T cells have been shown to play an important role in the inflammatory response observed in the gut of SGVHD mice. Time course studies revealed significant increases in the migration of CD4+ T cells as early as day 14 post- BMT into the colon of CsA mice as well as significant elevated mRNA levels of cell adhesion molecules. Homing studies revealed that a labeled CD4+ T cell line, generated from SGVHD mice, migrated in larger numbers into the gut of CsA-treated mice compared to control animals. This study demonstrated that CD4+ T cells responsible for the pathogenesis observed in murine SGVHD are present early after BMT in colons of CsA-treated mice, suggesting that during the 21 days of immunosuppression therapy functional mechanisms are in place that result in increased homing of effector cells to colons of CsA-treated mice.

Despite being the first biochemical reaction to be discovered, the glycine conjugation pathway remains poorly characterised. It has generally been assumed that glycine conjugation serves to increase the water solubility of organic acids, such as benzoic acid and isovaleric acid, in order to facilitate urinary excretion of these compounds. However, it was recently suggested that the conjugation of glycine to benzoate should be viewed as a neuroregulatory process that prevents the accumulation of glycine, a neurotransmitter, to toxic levels. The true importance of glycine conjugation in metabolism is therefore not well understood. However, no genetic defect of glycine conjugation has ever been reported. This seems to suggest that glycine conjugation is a fundamentally important metabolic process, whatever its function may be. Therefore, a major objective of this thesis was to develop a deeper understanding of glycine conjugation and its metabolic significance. A review of the literature on GLYAT and glycine conjugation suggested that the primary purpose of glycine conjugation is indeed to detoxify benzoate and other aromatic acids of dietary origin. However, the commonly held assumption, that glycine conjugation increases the water solubility of aromatic acids in order to facilitate urinary excretion, seems to be incorrect. A better explanation for the detoxification of benzoate by means of glycine conjugation is based on hydrophilicity, not water solubility. Because of its lipophilic nature, benzoic acid is capable of passively diffusing across the mitochondrial inner membrane into the matrix space, where it accumulates due to the pH gradient over the inner membrane. Although benzoate can be exported from the matrix by organic anion transporters, this process would likely be futile because benzoic acid can simply diffuse back into the matrix. Hippurate, however, is significantly less lipophilic and therefore less capable of diffusing into the matrix. It is therefore not transport out of the mitochondrial matrix that is facilitated by glycine conjugation, but rather the ability of the glycine conjugates to re-enter the matrix that is decreased. The conversion of benzoate to hippurate is a two-step process. First, benzoate is activated by an ATP-dependent acid:CoA ligase (ACSM2A) to form the more reactive benzoyl-CoA. Second, glycine N-acyltransferase (GLYAT) catalyses the formation of hippurate and CoASH from benzoyl-CoA and glycine. Another major objective of this thesis was to gain a better understanding of the structure and function of the GLYAT enzyme. While the substrate selectivity and enzyme kinetics of GLYAT have been investigated to some extent, almost nothing has been published on the structure, active site, or catalytic mechanism of GLYAT. Furthermore, while interindividual variation in the rate of glycine conjugation has been reported by several researchers, it is not known if, or how, genetic variation in the human GLYAT gene contributes to this interindividual variation. To address these issues, systems for the bacterial expression of recombinant bovine GLYAT and recombinant human GLYAT were developed. Because no crystal structure of GLYAT has been reported, homology modelling was used to generate a molecular model of bovine GLYAT. By comparing the molecular model to other acyltransferases for which the catalytic residues were known, Glu227 of bovine GLYAT was identified as a potential catalytic residue. Site directed mutagenesis was used to generate an E227Q mutant recombinant bovine GLYAT lacking the proposed catalytic residue. Characterisation of this mutant suggested that Glu227 was indeed the catalytic residue, and the GLYAT catalytic mechanism was elucidated. The molecular model was also used to identify Asn131 of bovine GLYAT as a potential active site residue. Site-directed mutagenesis was used to generate an N131C mutant, which was sensitive to inhibition by the sulfhydryl reagent DTNB. This suggests that the Asn131 residue of bovine GLYAT may be situated in the active site of bovine GLYAT, but more work is needed to confirm this result. Finally, site-directed mutagenesis was used to generate variants of recombinant human GLYAT corresponding to six of the known SNPs in the human GLYAT gene. Expression and characterisation of the recombinant human GLYAT variants revealed that the enzyme activity and KM (benzoyl-CoA) parameter of the recombinant human GLYAT were influenced by SNPs in the human GLYAT gene. This suggests that genetic variation in the human GLYAT gene could partly explain the interindividual variation in the rate of glycine conjugation observed in humans. Interestingly, the SNPs that negatively influenced enzyme activity also had low allele frequencies, suggesting that there may be some selective advantage to having high GLYAT activity. / PhD (Biochemistry), North-West University, Potchefstroom Campus, 2014

Le dibenzoylméthane (DBM) a été étudié comme catalyseur pour la copolymérisation par ouverture de cycle du L-lactide (LA) et du ε-caprolactone (CL) amorcée par des alcools en masse à haute température. Des copolymères présentant des structures gradient à statistique ont été formés. L’étude cinétique a mis en évidence que le DBM est un faible activateur de bout de chaîne et de monomère, l’apparente accélération de la copolymérisation étant due à la formation in situ d’acides carboxyliques catalysant la réaction à leur tour. L’acide benzoïque (BA), un acide carboxylique faible, a ensuite été étudié pour les homopolymérisations par ouverture de cycle du LA et du CL amorcées par des alcools en masse à haute température. L’étude cinétique a mis en évidence un mécanisme bifonctionnel et une différence de réactivité des deux monomères en présence de BA validés par des calculs théoriques. Une gamme de copolymères statistiques présentant différentes compositions ont été synthétisés par copolymérisation par ouverture de cycle du LA et CL catalysé par BA et amorcé par différents alcools en masse à haute température. Finalement, plusieurs catalyseurs organiques ont été testés pour la copolymérisation du LA et CL. / Dibenzoylmethane has been investigated as organocatalyst for the bulk ring-opening copolymerization (ROcP) of L-Lactide (LA) and ε-caprolactone (CL) initiated by alcohols at high temperature. Copolymer presenting a gradient to statistical structure has been generated. Kinetic study has pointed out that DBM is a poor chain end and monomer activator, the apparent acceleration of the ROcP process may be due to the in situ generation of carboxylic acids which can catalyze the reaction as well. Benzoic acid, a weak carboxylic acid, has then been investigated for the efficient bulk ring-opening polymerization (ROP) of LA and CL initiated by various alcohols at high temperature. The kinetic study has pointed out that LA and CL have different reactivity in presence of benzoic acid which acts as a bifunctional activator. The experimental results were supported by computational calculations. An array of statistical copolymer of varying LA/CL compositions have been synthesized by ROcP of LA and CL catalyzed by BA in presence of various alcohol as initiators in bulk at high temperature. Finally, miscellaneous organocatalysts have been tested for the ROcP of LA and CL.

In this study, silver nanorods and nanospheroids were prepared both in aqueous solution and on the surface of glass slides through seed-mediated growth approach at room temperature and used as a surface enhanced Raman scattering (SERS) substrate. The synthesis of metallic nanorods was started with the production of silver nanospheres as seed utilizing sodium borohydride and trisodium citrate as reducing and capping agents, respectively. These seeds were then added to a growth solution containing additional silver salt, ascorbic acid and cetyltrimethylammonium bromide (CTAB.) Nanorod preparation conditions were first optimized in solution phase. The plasmon absorption of the formed nanocrystals was monitored by UV-Visible spectrometry. The largest red shift in the longitudinal plasmon resonance absorption of silver nanostructures was tried to be achieved in order to realize the highest electromagnetic enhancement in Raman measurements. The images of the formed nanorods were recorded using field emission scanning electron microscopy (FE-SEM). The optimized colloidal growth conditions were adopted for the growth of nanorods on the surface of the glass substrate. Sol-gel coated glass slides were used in order to increase the porosity on the surface for an effective seeding process. We reported the development of a novel SERS substrate prepared by growing silver nanorods directly on the surface of glass surface without using any linker molecule. The SERS performances of the nanorod growth surfaces were evaluated with crystal violet (CV), brilliant cresyl blue (BCB) and benzoic acid (BA). Some modifications such as the increase in the AgNO3 concentration in the growth solution and the addition of hydrocarbons to the growth solution were investigated for the enhancement of the SERS signal. The intense spectra obtained for the model compounds demonstrated the efficiency of the prepared substrate for the SERS enhancement and its potential as a SERS detection probe for chemical and biological analysis.

Spherical agglomerates of benzoic acid crystals have been successfully prepared by drowning-out crystallization in three solvent partial miscible mixtures. Benzoic acid is dissolved in ethanol, bridging liquid is added and this mixture is fed to the agitated crystallizer containing water as the anti-solvent. Small crystals are produced by crystallization of the substance, and the crystals are agglomerated through the action of the bridging liquid. Different solvents: chloroform, toluene, heptane, pentane, cyclohexane, ethyl acetate and diethyl ether are chosen as bridging liquids, all being low soluble in water and showing good wettability for benzoic acid crystals. The influence of process conditions such as concentration of solute, agitation rate, feeding rate, amount of bridging liquid and temperature on the properties of benzoic acid spherical agglomerates, are investigated. Different sets of experiments were accomplished to track how the properties of the particles gradually change during the normal spherical crystallization experiment. Other sets of experiments were performed to examine the influence of agitation and process time for agglomeration. The product properties such as particle size distribution, morphology and mechanical strength have been evaluated. The mechanical strength of single agglomerates has been determined by compression in a materials testing machine, using a 10 N load cell. Compression characteristics for single agglomerates are compared with the data on bed compression. The present study shows that the bridging liquid has significant influence on the product properties, using diethyl ether and ethyl acetate no agglomerates are formed. Using any of the other five solvents (chloroform, toluene, heptane, pentane, and cyclohexane) spherical agglomerates are formed, as long as a sufficient amount of the bridging liquid is used. Using cyclohexane as bridging liquid at 5°C and toluene at 20°C the particles are larger compared to particles formed at other conditions. The highest particle fracture stress is obtained by using toluene as the bridging liquid at 5 and 20°C. Particle morphology depends on the bridging liquid used and the particles are completely spherical when toluene and pentane are used as bridging liquids. Different process parameters are found to have a significant influence on the physico-mechanical properties of the product. The range of operation for spherical agglomeration is relatively narrow and only at certain conditions spherical agglomerates are produced. With increasing amount of bridging liquid the particle size and strength increase and the morphology improves. Particle size decreases and the fracture force increases with increasing feeding rate, but the morphology remains unchanged. For all the solvents, the particle size and the fracture stress increase with decreasing temperature. For four of the solvents the morphology improves with decreasing temperature. For cyclohexane the result is the opposite, in that the particles are spherical at 20°C and irregular at 5°C. Spherical agglomerates of benzoic acid, both as single particles as well as in the form of a bed, have a high compressibility and low elastic recovery, properties that are favorable for direct tabletting. As the feed solution is supplied to the crystallizer the amount of benzoic acid that can crystallize actually does crystallize fairly rapidly. Hydrodynamics are responsible for bringing particles together for the agglomeration. Experiments reveal that during the gradual addition of the feed to the agitated aqueous solution, both particle size and particle number increases. It is clear from the experiments that not only further addition of feed solution leads to larger product particles but also continued agitation. Along the course of the process the properties of the particles change gradually but substantially. By continued agitation, the particle porosity decreases, density, strength gradually increases and also the spherical shape develops gradually. / QC 20110419