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An in situ technique with X-ray diffraction analysis has been developed to study the crystallization of lactose in humid air. This technique was used in association with ex situ scanning electron microscopy to determine changes in phase composition and morphology during crystallization. Individual spherical particles of spray-dried lactose plasticize and coalesce upon absorption of moisture. Following an induction period, crystallization is rapid with the appearance of the anhydrous 5:3 phase containing both R and β isomers of lactose, R-lactose monohydrate and β-lactose, almost simultaneously. The 5:3 phase decomposed as the other two phases developed. After extended exposure to humid air, only R-lactose monohydrate and β-lactose were observed. The predominant particle habit observed in the fully crystallized lactose is platelet. These observations are rationalized in terms of the restricted molecular diffusion in plasticized lactose preventing movement of the β-lactose isomer toward developing R-lactose monohydrate crystals with the result that normal solution phase inhibition of growth of the (01 h1) face leading the tomahawk shaped crystal lactose does not occur. The restricted diffusional conditions also favor the formation of the mixed isomer 5:3 phase, resulting in the entrapment of both isomers during crystallization.

Vertically-oriented zinc oxide (ZnO) nanowires were synthesized on glass and silicon substrates by Pulsed Laser Deposition and without the use of a catalyst. An intermediate c-axis oriented nanotextured ZnO seed layer in the form of nanowall network with honey comb structure allows the growth of high quality, self-forming, and vertically-oriented nanowires at relatively low temperature (<400 °C) and under argon atmosphere at high pressure (>5 Torr). Many parameters were shown to affect the growth of the ZnO nanowires such as gas pressure, substrate–target distance, and laser energy. Growth of a c-axis-crystalline array of nanowires growing vertically from the energetically favorable sites on the seed layer is observed. Nucleation occurs due to the matching lattice structure and the polar nature of the ZnO seed layer. Morphological, structural, and optical properties were investigated. X-ray diffraction (XRD) revealed highly c-axis aligned nanowires along the (002) crystal plane. Room temperature photoluminescence (PL) measurements showed a strong and narrow bandwidth of Ultraviolet (UV) emission, which shifts to lower wavelength with the increase of pressure.

Phase compositions, transient phases, and morphology of the crystallization of freeze-dried lactose/salt mixtures in humid air were estimated by in situ X-ray diffraction analysis complemented by ex situ scanning electron microscopy, powder diffraction, and analysis of the solid state R/β anomeric ratios by gas-liquid chromatography. The salts studied are calcium chloride (CaCl 2 ), magnesium chloride (MgCl 2 ), potassium chloride (KCl), and sodium chloride (NaCl) with lactose/salt molar ratios of 2:1, 4:1, and 9:1 mol/mol. Following an induction period during which water is sorbed, crystallization is rapid and the predominant phases observed using the in situ method in freeze-dried lactose/magnesium chloride (MgCl 2 ), sodium chloride (NaCl), and potassium chloride (KCl) are mixtures of R-lactose monohydrate and β-lactose. In general, the R/β ratio of the solid state as measured by gas-liquid chromatography was similar to the crystalline phase composition as measured by X-ray diffraction. A transient phase appears in lactose/KCl (4:1 and 9:1 mol/mol), lactose/MgCl 2 (9:1 mol/mol), and lactose/NaCl (9:1 mol/mol), namely, R/β mixed phase. Another transient effect observed with nearly all the lactose-salt mixtures was the observation of a subtle shift in the lattice parameters of R-lactose from a ) 8.006 Å, b ) 21.562 Å and c ) 4.800 Å for short crystallization times to a ) 7.982 Å, b ) 21.562 Å, and c ) 4.824 Å for longer times. The transient effects, namely, the observation of the R/β mixed phase and the distortion in R-lactose monohydrate lattice parameters, are explained in terms of stresses induced during the rapid onset of crystallization.

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The primary objective of this paper is to compare the sorption characteristics of hydroxypropylmethylcellulose (HPMC) and hard gelatin (HG) capsules and their ability to protect capsule contents. Moisture sorption and desorption isotherms for empty HPMC and HG capsules have been investigated using dynamic vapour sorption (DVS) at 25°C. All sorption studies were analysed using the Young-Nelson model equations which distinguishes three moisture sorption types: monolayer adsorption moisture, condensation and absorption. Water vapour diffusion coefficients (D), solubility (S) and permeability (P) parameters of the capsule shells were calculated. ANOVA was performed with the Tukey comparison test to analyse the effect of %RH and capsule type on S, P, and D parameters. The moisture uptake of HG capsules were higher than HPMC capsules at all %RH conditions studied. It was found that values of D and P across HPMC capsules were greater than for HG capsules at 0-40 %RH; whereas over the same %RH range S values were higher for HG than for HPMC capsules. S values decreased gradually as the %RH was increased up to 60% RH. To probe the effect of moisture ingress, spray dried lactose was loaded into capsules. Phase evolution was characterised by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and differential scanning calorimetry (DSC). The capsules under investigation are not capable of protecting spray dried lactose from induced solid state changes as a result of moisture uptake. For somewhat less moisture sensitive formulations, HPMC would appear to be a better choice than HG in terms of protection of moisture induced deterioration.

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