1,127 research outputs found
Evaluation of effect of the primary particle size on compactibility of spray-dried lactoses
Spray-dried lactose is one of the most used filler-binders in direct compaction of tablets.
Spray-dried lactose is produced by spray-drying a suspension of α-lactose monohydrate
crystals in a saturated aqueous solution of lactoses. The resulting product is composed of
spherical particles, containing 80-85% crystals of α-lactose monohydrate (primary particles) and 15-20% amorphous lactose
The compactibility of two commercial spray-dried lactoses, Pharmatose® DCL 11
(DCL11), prepared from α-lactose monohydrate with a median primary particle size of 34
µm and a new product, Pharmatose® DCL 14 (DCL14), prepared from 20 µm primary
particles, were investigated
Steady-state nucleation rate and flux of composite nucleus at saddle point
The steady-state nucleation rate and flux of composite nucleus at the saddle
point is studied by extending the theory of binary nucleation. The
Fokker-Planck equation that describes the nucleation flux is derived using the
Master equation for the growth of the composite nucleus, which consists of the
core of the final stable phase surrounded by a wetting layer of the
intermediate metastable phase nucleated from a metastable parent phase recently
evaluated by the author [J. Chem. Phys. {\bf 134}, 164508 (2011)]. The
Fokker-Planck equation is similar to that used in the theory of binary
nucleation, but the non-diagonal elements exist in the reaction rate matrix.
First, the general solution for the steady-state nucleation rate and the
direction of nucleation flux is derived. Next, this information is then used to
study the nucleation of composite nucleus at the saddle point. The dependence
of steady-state nucleation rate as well as the direction of nucleation flux on
the reaction rate in addition to the free-energy surface is studied using a
model free-energy surface. The direction of nucleation current deviates from
the steepest-descent direction of the free-energy surface. The results show the
importance of two reaction rate constants: one from the metastable environment
to the intermediate metastable phase and the other from the metastable
intermediate phase to the stable new phase. On the other hand, the gradient of
the potential or the Kramers crossover function (the commitment or
splitting probability) is relatively insensitive to reaction rates or
free-energy surface.Comment: 12 pages, 6 figures, to be published in Journal of Chemical Physic
On Psychotic Phenomena and Unruliness: studies on the childhood risk for severe mental illness
Psychiatric disorders in adulthood, including severe mental illnesses, commonly have antecedents in childhood or adolescence. A better understanding of the developmental pathways of psychiatric problems in early childhood might help to achieve a more comprehensive understanding of severe mental illness in adults. The general aim of this thesis was to gain insights into the neurodevelopmental pathways of children at increased risk for severe mental illness. Here we focussed on two prevalent yet impairing psychiatric phenotypes of childhood: psychotic phenomena and disruptive behaviour problems. Each of these constellations of psychiatric symptoms is in its own right predictive of substantially poorer psychosocial functioning in the long term. All studies described in this thesis were conducted in the context of the Generation R Study, a population-based cohort study in Rotterdam, the Netherlands. The findings and interpretations of the individual studies are discussed in the broader context of the existing literature. More specifically, several methodological considerations are discussed pertaining to the neurodevelopmental model of psychosis, the neurodevelopmental model of disruptive behaviour, analytical methods of behavioural heterogeneity, assessment of psychotic experiences in children and the link between cannabis use and psychopathology. We conclude with several recommendations for improved clinical practice and future research
Phase behavior of a system of particles with core collapse
The pressure-temperature phase diagram of a one-component system, with
particles interacting through a spherically symmetric pair potential in two
dimensions is studied. The interaction consists of a hard core plus an
additional repulsion at low energies. It is shown that at zero temperature,
instead of the expected isostructural transition due to core collapse occurring
when increasing pressure, the system passes through a series of ground states
that are not triangular lattices. In particular, and depending on parameters,
structures with squares, chains, hexagons and even quasicrystalline ground
states are found. At finite temperatures the solid-fluid coexistence line
presents a zone with negative slope (which implies melting with decreasing in
volume) and the fluid phase has a temperature of maximum density, similar to
that in water.Comment: 11 pages, 15 figures included. To appear in PRE. Some figures in low
quality format. Better ones available upon request from [email protected]
An integral equation approach to effective interactions between polymers in solution
We use the thread model for linear chains of interacting monomers, and the
``polymer reference interaction site model'' (PRISM) formalism to determine the
monomer-monomer pair correlation function for dilute and
semi-dilute polymer solutions, over a range of temperatures from very high
(where the chains behave as self-avoiding walks) to below the
temperature, where phase separation sets in. An inversion procedure, based on
the HNC integral equation, is used to extract the effective pair potential
between ``average'' monomers on different chains. An accurate relation between
, [the pair correlation function between the polymer
centers of mass (c.m.)], and the intramolecular form factors is then used to
determine , and subsequently extract the effective c.m.-c.m. pair
potential by a similar inversion procedure. depends on
temperature and polymer concentration, and the predicted variations are in
reasonable agreement with recent simulation data, except at very high
temperatures, and below the temperature.Comment: 13 pages, 13 figures, revtex ; revised versio
Cytotoxicity of oleandrin isolated from the leaves of Nerium indicum Mill. on several human cancer cell lines
Finding anticancer drugs from natural resources still proceeds. Oleandrin isolated from Nerium indicum Mill. inhibited the growth of mieloma cell line in vitro better than that of vincristine sulphate. This study was aimed to determine the cytotoxic effect of oleandrin on various human cancer cell lines. Cytotoxic test of oleandrin on seven human cancer cell lines was done by SRB-method. The analysis was conducted by comparing the ID50 of oleandrin with that of doxorubicin and cisplatin as positive controls. This result indicated that oleandrin possessed the best cytotoxic effect on breast cancer (MCF7) with ID50 at 8.85 nM. Keywords : Oleandrin, cytotoxicity, human cancer cells, ID5
Hyper-Palatable Foods: Development of a Quantitative Definition and Application to the US Food System Database
Objective: Extensive research has focused on hyper-palatable foods (HPF); however, HPF are defined using descriptive terms (e.g., fast foods, sweets), which are not standardized and lack specificity. The study purpose was to develop a quantitative definition of HPF and apply the definition to the Food and Nutrient Database for Dietary Studies (FNDDS) to determine HPF prevalence in the US food system.
Methods: A numeric definition of HPF was developed by extracting common HPF descriptive definitions from the literature and using nutrition software to quantify ingredients of fat, simple sugars, carbohydrates, and sodium. The definition was applied to the FNDDS.
Results: HPF from the literature aligned with three clusters: (1) fat and sodium (> 25% kcal from fat, ≥ 0.30% sodium by weight), (2) fat and simple sugars (> 20% kcal from fat, > 20% kcal from sugar), and (3) carbohydrates and sodium (> 40% kcal from carbohydrates, ≥ 0.20% sodium by weight). In the FNDDS, 62% (4,795/7,757) of foods met HPF criteria. The HPF criteria identified a variety of foods, including some labeled reduced or low fat and vegetables cooked in creams, sauces, or fats.
Conclusions: A data-derived HPF definition revealed that a substantial percentage of foods in the US food system may be hyper-palatable, including foods not previously conceptualized as hyper-palatable
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