Modeling physical-chemical properties of High Dilutions: an electrical conductivity study

The most common way to perform succussions is to place a liquid preparation inside a glass vessel and beat it vigorously against a hard elastic surface, either manually or using a mechanical apparatus. This procedure has been assumed able to transfer mechanical energy to the molecular level, where it becomes available to perform chemical work. Such interpretation has been enforced by observed changes in the electrical conductivity (EC) of High Dilutions (HD) due to succussion. In order to address this question, we compared the electrical conductivity changes of HD prepared from Vincristine sulfate (VCR) samples with those of an inert solvent. Samples were produced through manual and mechanical succusions in order to observe the influence of bubbles production. The results confirmed the timing of EC changes but these were equivalent for VCR and solvent, except for VCR 1cH samples. Also, the production of bubbles does not affect the EC in an extent able to distinguish succussion procedures. We concluded that the physical-chemical properties of HD can be modeled by chemical and diffusive mechanisms typical of distilled water. Keywords: Succussion, electrical conductivity, high dilutions, distilled water, modeling.  Modelagem de propriedades físico-químicas das Altas Diluições: o estudo da condutividade elétrica Resumo A maneira mais comum de realizar sucussões é manter uma preparação líquida dentro de um frasco de vidro, e agitá-la violentamente usando um dispositivo mecânico ou batendo-a, manualmente, contra um anteparo rígido, porém elástico. Este procedimento tem sido interpretado como um mecanismo capaz de transferir a energia mecânica da agitação, para níveis moleculares, onde ela se tornaria disponível para a realização de trabalho químico. Tal interpretação tem sido estimulada pela observação de alterações na condutividade elétrica (CE) de Altas Diluições (HD), devido àsucussão. Visando modelar esta questão, comparou-se a alteração da CE de amostras preparadas a partir de Sulfato de Vincristina (VCR) com amostras equivalentes (controle) preparadas apenas com o solvente água destilada. As amostras foram produzidas por sucussão mecânica e manual, a fimd e observar a influéncia da produção de bolhas. Os resultados confirma que a CE varia com o tempo, porém tais variações são equivalentes para VCR e controle, exceto para as amostras VCR 1cH. Também, a produção de bolhas não afeta a CE de forma a permitir usá-la para distinguir os diferentes procedimentos de sucussão. Concluimos que as propriedades físico-químicas da HDs podem ser modeladas por mecanismos químicos e difusivos, típicos para a água destilada. Palavras-chave: Sucussão, condutividade elétrca, altas diluições, água destilada, modelagem.  Modelo de propiedades físico-químicas de las Altas diluciones: un estudio de la conductividad eléctrica Resumen La manera más común para llevar a cabo sucuciones es mantener una preparación líquida dentro de un recipiente de vidrio, agitando violentamente utilizando para esto un aparato mecánico, o golpes manuales contra una superfície dura mas elástica. Este procedimiento ha sido interpretado como un mecanismo capaz de transferir la energía mecánica a nivel molecular, donde es posible realizar el trabajo químico. Tal interpretación ha sido estimulada por los cambios observados en la conductividad eléctrica (CE) de las Altas diluciones (HD), debido al procedimiento de la sucucion. A fin de abordar este punto, se compararon los cambios en la conductividad eléctrica de HD preparadas a partir de Sulfato de Vincristina (VCR) con muestras de solvente inerte. Las muestras fueron producidas a través de sucuciones mecánicas y manuales, con el fin de observar la influencia de la producción de burbujas. Los resultados confirmaron el cambio em la CE, pero estos cambios fueron equivalentes para VCR y solvente, con excepción de las muestras VCR 1cH. Asimismo, la producción de burbujas no afecta la CE en una medida capaz de distinguir las diferentes maneras de sucución. Concluimos que las propiedades físico-químicas de HD pueden ser modeladas por mecanismos químicos y difusivos típicos del agua destilada. Palabras-clave: Sucución, conductividad eléctrica, alta diluciones, agua destilada, modelo.  Correspondence author: Carlos Renato Zacharias, [email protected] How to cite this article: Holandino C, Harduim R, Veiga VF, Garcia, S. Zacharias CR. Modeling physical-chemical properties of High Dilutions: an electrical conductivity study. Int J High Dilution Res [online]. 2008 [cited YYYY Mmm DD]; 7(25): 165-173. Available from: http://journal.giri-society.org/index.php/ijhdr/article/view/319/375. ÂÂÂ

Structural insights into metal-metalloid glasses from mass spectrometry

Despite being studied for nearly 50 years, smallest chemically stable moieties in the metallic glass (MG) could not be found experimentally. Herein, we demonstrate a novel experimental approach based on electrochemical etching of amorphous alloys in inert solvent (acetonitrile) in the presence of a high voltage (1 kV) followed by detection of the ions using electrolytic spray ionization mass spectrometry (ESI MS). The experiment shows stable signals corresponding to Pd, PdSi and PdSi2 ions, which emerges due to the electrochemical etching of the Pd80Si20 metallic glass electrode. These fragments are observed from the controlled dissolution of the Pd80Si20 melt-spun ribbon (MSR) electrode. Annealed electrode releases different fragments in the same experimental condition. These specific species are expected to be the smallest and most stable chemical units from the metallic glass which survived the chemical dissolution and complexation (with acetonitrile) process. Theoretically, these units can be produced from the cluster based models for the MG. Similar treatment on Pd40Ni40P20 MSR resulted several complex peaks consisting of Pd, Ni and P in various combinations suggesting this can be adopted for any metal-metalloid glass.

Can the Lewis basicity of an isolated solvent molecule be used for characterizing solvent effects?

Background: The ubiquitous Lewis acid/base interactions are important in solution processes. Analytical chemistry may benefit of a better understanding of the role of Lewis basicity, at the molecular level or acting through a bulk solvent effect. Objective: To clearly delineate (i) the basicity at a molecular level, hereafter referred as solute basicity, and (ii) the solvent basicity, which is a bulk-liquid property. Method: The literature that relates Lewis basicity scales and solvent effects is analyzed. A special focus is placed on two extensive scales, the Donor Number, DN, and the BF3 affinity scale, BF3A, which were obtained by calorimetric measurement on molecules as solutes diluted in a quasi-inert solvent, and therefore define a molecular Lewis basicity. We discuss the validity of these solute scales when regarded as solvent scales, in particular when the basicity of strongly associated liquids is discussed. Results: We demonstrate the drawbacks of confusing the Lewis basicity of a solvent molecule, isolated as solute, and that of the bulk liquid solvent itself. Conclusion: Consequently, we recommend a reasoned use of the concept of Lewis basicity taking clearly into account the specificity of the process for which a Lewis basicity effect may be invoked. In particular, the action of the Lewis base, either as an isolated entity, or as a bulk liquid, must be distinguished.

Considering the Experimental Use of Temozolomide in Glioblastoma Research

Temozolomide (TMZ) currently remains the only chemotherapeutic component in the approved treatment scheme for Glioblastoma (GB), the most common primary brain tumour with a dismal patient’s survival prognosis of only ~15 months. While frequently described as an alkylating agent that causes DNA damage and thus—ultimately—cell death, a recent debate has been initiated to re-evaluate the therapeutic role of TMZ in GB. Here, we discuss the experimental use of TMZ and highlight how it differs from its clinical role. Four areas could be identified in which the experimental data is particularly limited in its translational potential: 1. transferring clinical dosing and scheduling to an experimental system and vice versa; 2. the different use of (non-inert) solvent in clinic and laboratory; 3. the limitations of established GB cell lines which only poorly mimic GB tumours; and 4. the limitations of animal models lacking an immune response. Discussing these limitations in a broader biomedical context, we offer suggestions as to how to improve transferability of data. Finally, we highlight an underexplored function of TMZ in modulating the immune system, as an example of where the aforementioned limitations impede the progression of our knowledge.

Study on inert solvent for preparation based on GO/EP composite

PurposeThe dispersity of graphene oxide (GO) has an important effect on the properties of epoxy resin (EP) composites. Many modification and dispersion methods require the use of inert solvents which do not participate in the modification reaction, although GO can be uniformly dispersed in water and alcohol solvents. Based on this requirement, several inert solvents were selected as dispersion solvents to find out the suitable inert solvent for GO dispersion into EP matrix.Design/methodology/approachSeveral inert solvents with different solubility parameters were selected as dispersion solvents to prepare GO/EP composite. The microstructure, mechanical properties, insulation properties, dielectric properties and thermal property of the composite were characterized, which was due to find suitable inert solvent for GO dispersion into EP matrix.FindingsThe dispersity of N, N-dimethylformamide (DMF) was the best stable suspension state when it was used as solvent instead of occurring sedimentation and agglomeration. Moreover, DMF was further confirmed as a suitable inert solvent for the dispersion of GO into EP according to the mechanical properties, insulation properties and thermal conductivity characterization.Research limitations/implicationsThe dispersion of GO in solvents has already been researched, but the traditional solvents, such as alcohols and water, has shown their limitations with the increase of modification methods, which were not suitable for the modification environment such as cyanate graft modification. Therefore, it was very important to choose a kind of inert solvent for dissolving EP matrix and dispersing GO better.Originality/valueSeveral inert solvents were used to disperse GO into EP, and the influence of different dispersing solvents on the adhesive was discussed through the analysis of the mechanical properties, insulation properties and thermal conductivity, which was due to explore the inert solvent suitable for GO dispersion.

AN INVITRO COMPARATIVE EVALUATION OF ANTICANDIDAL HERBS (GINGER & TURMERIC) ON STREPTOCOCCUS MUTANS

Aim: To comparatively evaluate the antimicrobial effect of turmeric and ginger extracts on Streptococcus mutans in in-vitro conditions. Material & Method: An in-vitro experimental study was conducted in a laboratory setting. Ethanolic extract of Ginger and Turmeric was prepared separately by cold masseration technique. The extract of each was then diluted with an inert solvent, Dimethyl Formamide, to obtain 5 different concentrations (2%, 4%, 6%, 8%, and 10%) of each. 0.2% chlorhexidine was used as a positive control and dimethyl formamide was used as negative control. The different extracts, along with controls, were then subjected to microbiological investigation to determine which gave a wider zone of inhibition against streptococcus mutans. The zone of inhibition was measured in millimeters. Results: Turmeric extracts presented the largest zone of inhibition 33mm at the concentration of 8%, while Ginger extract showed a zone of inhibition of 34mm at the concentration of 10%. Conclusion: Ethanolic extract of Turmeric demonstrated antimicrobial activity against Strptococcus Mutans at a lower concentration than that of Ginger. Keywords: Ginger, Turmeric, Streptococcus Mutans.

Synthesis and purification of metallooctachlorophthalocyanines

A detailed synthetic procedure based on the use of urea, dichlorophthalic acid, respective transition metal halides and [NH4]2[MoO4] as a catalyst in the melt or by using 1,2,4-trichlorobenzene as a high-boiling inert solvent is described to gain 2,3,9,10,16,17,23,24-metallooctachlorophthalocyanines (MPcCl8compounds with M=Mn, Fe, Co, Ni, Cu). In cases that a first purification by subsequent treatment of the crude materials with HCl, NaOH and HCl would not give rise to analytically pure compounds, a second novel purification by using pyridine is described. The degree of purity, exceeding always 98%, is determined by thermogravimetric analysis. Comparative IR, UV/Vis and PXRD studies of the MPcCl8compounds are reported.