Different Methods Of Investigation Research Articles

Hydrogen bonds with fluorine. Studies in solution, in gas phase and by computations, conflicting conclusions from crystallographic analyses

Hydrogen bonds with organic fluorine are discussed on the background of an ongoing controversy, with an overview on the different methods of investigation, and with many examples, reaching from simple complexes to those involving nucleic acids. Often overlooked experimental values for the free energy of hydrogen bond involving C–F as acceptor depend on the solvent; in CCl4 they amount with moderately acidic donors to ΔG = 6 kJ mol−1, much higher than with other halogens, placing fluorine as an acceptor between alkanes and arenes. The measured ΔG values increase from primary to secondary to tertiary C–F moieties, ab initio calculations predict an increase from sp3 to sp2 to sp1 carbon. Simultaneous action of several X–H⋯F bridges can lead, even in polar media such as CDCl3/CD3CN, to binding constants of 70 [M−1]. Spectroscopic measurements unequivocally establish the presence of such hydrogen bonds, furnishing H⋯F distances as small as 2.02 Å, and X–H⋯F angles close to 180°, which generally agrees with most computational analyses. All computations point to dominating dispersive contributions, in particular for the very weak C–H⋯F interactions. In contrast, crystallographic analyses have led to controversial conclusions. Screening of databases, essentially based on X-ray determinations, often showed only very few structures with short H⋯F distances, for which reason the existence of such hydrogen bonds has been generally questioned. Some database evaluations, however, have shown enough cases for interactions between fluorine and X–H donors, mostly with H⋯F distances around 2.5 Å and X–H⋯F angles around 130°, which makes it difficult to distinguish hydrogen bonds from dispersive interactions. In several cases intermolecular H⋯F bridges dominate, and play a significant role in packing motifs, even when the underlying molecules tend to form only intramolecular bridges in solution. Generally, structures with intramolecular bonds give a clearer picture of X–H⋯F geometries. The limitations in deriving from crystal studies non-covalent binding mechanisms for weak single interactions are discussed.

The Effect of Food on the Oral Bioavailability of Drugs: a Review of Current Developments and Pharmaceutical Technologies for Pharmacokinetic Control

Here we review the mediation of the food effects on drugs by pharmaceutical technologies. The pharmacokinetics of drugs are affected by the interaction of drugs with food, which changes drug physicochemical and physiological properties (food effects). Several pharmaceutical technologies may be used to control food effects. Drugs exhibit different patterns of solubilization depending on release formulations. Formulations such as nanoparticle, solid dispersion and cyclodextrin systems, may control the solubility and release of insoluble drugs. Other controlled-release technologies, such as osmotic-controlled release or colon-specific delivery systems may also control food effects. As the structure of drug candidates becomes more complex, different methods of investigation, such as in vitro and in vivo correlation and in silico simulation will be required to predict drug characteristics and food effects.

Evaluation of the Physical Stability of Zinc Oxide Suspensions Containing Sodium Poly-(acrylate) and Sodium Dodecylsulfate

The physical stability of zinc oxide (ZnO) aqueous suspensions has been monitored during two months by different methods of investigation. The suspensions were formulated with ZnO at a fixed concentration (5 wt%), sodium poly-(acrylate), as a viscosifier, and sodium dodecylsulfate (SDS), as a wetting agent. The rheological study shows that the suspensions exhibit a non-Newtonian, most often shear-thinning behavior and their apparent viscosity increases with polymer concentration. The rheograms of most of the ZnO suspensions do not vary during the experimental period. The viscoelastic properties of these suspensions, such as elastic or storage modulus (G′), viscous or loss modulus (G″) and phase angle (δ) were also examined. For% strains lower than 10%, all the formulations show strong elastic properties (G′ > G″, δ varies between 5 and 15°). Beyond 10% strain, the rheological behavior changes progressively from elastic to viscous (G″ > G′ for % strain >80%). Consistently, δ increases and reaches the 50–70° zone. Multiple light scattering (back-scattered intensity), measured with the Turbiscan ags, was used to characterize suspension physical stability (early detection of particle or aggregate size variations and particle/aggregate migration phenomena). Suspensions containing 0.4 and 0.6 wt% polymer remain stable and macroscopically homogeneous, without being affected by the change of particle size observed with a laser particle sizer. Sedimentation tests, pH, and ζ potential measurements versus time, also confirmed these findings.

Into the mind of the academic listener

This paper argues that we know too little of the mental processes in which a listener engages during an academic lecture; and that a better understanding of these processes would assist EAP instructors on pre-sessional courses to target their teaching more precisely. The account provides insights into listener behaviour from three possible perspectives, using three different methods of investigation. Firstly, it attempts to determine what proportion of a piece of monologic lecture-style input is likely to be decoded accurately by an intermediate range listener and, by extension, how dependent such a listener is likely to be upon strategies that compensate for gaps in understanding. Secondly, there is an examination of verbal reports produced by language learners undertaking two conventional comprehension tasks, in order to establish the extent to which the processes engaged differ from those that would be relevant in a lecture context. Finally, a model of the listening skill is briefly outlined; and attention is drawn to one area in particular (information handling) that, for reasons connected with the design of comprehension tasks, is not usually covered in L2 academic listening programmes.

Tracking a TB Network

Epidemiology Improvements in two very different methods of investigation led to better understanding of the dynamics of a tuberculosis (TB) outbreak in British Columbia, Canada. A 10-fold increase in TB cases was reported in a Canadian community between 2006 and 2008. Initial genotyping analysis by Gardy et al. suggested that the outbreak was clonal; however, whole-genome sequencing of M. tuberculosis isolates produced a different picture: The cases were the result of two outbreaks. Examination of historical isolates indicated that the two lineages were present before the recent outbreak, which suggested that it was a social or environmental effect, not a genetic mutation, which triggered the increase in cases. Social network analysis was then used to build a picture of risk behavior, interactions, and social meeting places. When this was combined with the whole-genome data, the investigators were able to identify sources of the outbreak and a likely contribution of increased crack cocaine use. As sequencing costs go down and network analyses become more sophisticated, it is likely that these strategies will be increasingly used in public health efforts. N. Engl. J. Med. 364 , 730 (2011).

Exploration and Exploitation Tradeoff in Fuzzy Reinforcement Learning

Difficulty of making a balance between exploration and exploitation in multiagent environment is a dilemma that does not have a clear answer and there are still different methods for investigation of this problem that all refer to it. In this paper, we provide a method based on fuzzy variables for making exploration and exploitation in multiagent environment. In this method, an effective agent (e in e-greedy method) is obtained which is updated using fuzzy variables in each step to manage tradeoff between exploration and exploitation.The proposed algorithm is investigated for determination an optimized path in the Grid World. In this method, agents effort to reach locations with a highest gain in a cooperative environment. Outcomes of the suggested fuzzy based algorithm compared with the results by conventional e-greedy method. In addition, quality improvement of interaction between exploration and exploitation is discussed.

Does it work? Why does it work? Reconciling difficult questions

Within medicine there is an agreed hierarchy of levels of research evidence with randomized controlled trials at the top and expert opinion at the bottom. When randomized controlled trials are the final stage in testing a treatment for which there is a sound theoretical basis both the 'Does it work?' and 'How does it work?' questions may be answered. However, when the theoretical basis is underdeveloped or contentious, then randomized controlled trials will provide only partial answers and other methods or methodologies may be needed to understand more about the mechanisms involved in the treatments. This paper aims to contribute to the debate about the nature of the evidence that is required in order to feel confident that people with communication difficulties will benefit from the treatments offered. The aim is not to discuss the relative merits of one methodology over another, but rather, by referring to one particular treatment, to show how knowledge gained from a range of research studies, using different methodologies, can be synthesized to increase one's understanding. The initial discussion focuses on two frameworks that have been developed specifically for the evaluation of healthcare interventions. This is followed by discussion of the research evidence for the Lidcombe Program of early stuttering intervention to illustrate some issues relevant to treatment development and evaluation in the field of communication difficulty. The evidence from randomized controlled trails is related to clinicians' needs. Finally, the potential value of an iterative approach is illustrated with reference to verbal contingencies, which are an essential component of the Lidcombe Program. This paper considers different sorts of evidence and their contribution to one's knowledge and practice. The content provides a practical example of how knowledge and understanding of a treatment approach can develop through a synthesis of knowledge from a programme of systematic research, from research outside the field of communication difficulty, and from the process of making sense of the experiences of both clinicians and clients who use the approach. The questions 'Does it work?' and 'How does it work?' are important and require different methods of investigation. Particular treatments may be viewed as better suited to one research methodology over another, but limiting research to one fails to provide the information that practitioners need in order to justify what they do and effectively to solve problems encountered in the application of particular approaches.

The drug-naïve OCD patients imaging genetics, cognitive and treatment response study: methods and sample description

To describe a protocol that was based on an integrative neurobiological model of scientific investigation to better understand the pathophysiology of obsessive-compulsive disorder and to present the clinical and demographic characteristics of the sample. A standardized research protocol that combines different methods of investigation (genetics, neuropsychology, morphometric magnetic resonance imaging and molecular neuroimaging of the dopamine transporter) obtained before and after treatment of drug-naïve adult obsessive-compulsive disorder patients submitted to a sequentially allocated 12-week clinical trial with a selective serotonin reuptake inhibitor (fluoxetine) and group cognitive-behavioral therapy. Fifty-two treatment-naïve obsessive-compulsive disorder patients entered the clinical trial (27 received fluoxetine and 25 received group cognitive-behavioral therapy). At baseline, 47 blood samples for genetic studies, 50 neuropsychological evaluations, 50 morphometrical magnetic resonance images and 48 TRODAT-1 single-photon emission computed tomography (SPECT) exams were obtained. After 12 weeks, 38 patients completed the protocol (fluoxetine = 20 and GCBT = 18). Thirty-eight neuropsychological evaluations, 31 morphometrical magnetic resonance images and 34 TRODAT-1 SPECT exams were obtained post-treatment. Forty-one healthy controls matched for age, gender, socioeconomic status, level of education and laterality were submitted to the same research procedures at baseline. The comprehensive treatment response protocol applied in this project allowing integration on genetic, neuropsychological, morphometrical and molecular imaging of the dopamine transporter data in drug-naïve patients has the potential to generate important original information on the neurobiology of obsessive-compulsive disorder, and at the same time be clinically meaningful.

INTEGRATED MODELLING ENVIRONMENT FOR DECISION MAKING SUPPORT IN SUPPLY CHAIN MANAGEMENT: CONCEPTUAL APPROACH

This study introduces an integrated modelling environment (IME) developed within the frames of Structured Analysis and Design Technology and intended for state analysis and prognosis of systems described according to General Systems Theory. The distinguishing feature of the IME is that it is to support an open domain model and integrate different forms of both data representation and expert knowledge. A conceptual model of the subject domain is used as a core of the IME to maintain every stage of modelling. Combined processing of data coming from simulation modules of the object's structure components, embedded geographic information system and expert system constitutes the main difference between the model and its prototypes. The IME is intended to formalize and integrate the general expert knowledge regarding the subject domain and dynamics of its development. The worked out modelling system provides using different methods for investigation of not-enough-formalized complex non-stationary spatial objects, ensures complex use of expert knowledge to form criteria and chose alternatives for more detail studying in the simulation mode.

Investigating risk factors for slips, trips and falls in New Zealand residential construction using incident-centred and incident-independent methods

Slip, trip and fall (STF) incidents, particularly falls from a height, are a leading cause of injury in the New Zealand residential construction industry. The most common origins of falls from a height in this sector are ladders, scaffolding and roofs, while slipping is the most frequent fall initiating event category. The study aimed to provide detailed information on construction industry STF risk factors for high-risk tasks, work equipment and environments, as identified from an earlier analysis of STF claims data, together with information to be used in the development of interventions to reduce STF risk in New Zealand residential construction. The study involved the use of both incident-centred and incident-independent methods of investigation, including detailed follow-up investigations of incidents and observations and interviews with workers on construction sites, to provide data on a wide range of risk factors. A large number of risk factors for residential construction STFs were identified, including factors related to the work environment, tasks and the use and availability of appropriate height work equipment. The different methods of investigation produced complementary information on factors related to equipment design and work organization, which underlie some of the site conditions and work practices identified as key risk factors for residential construction STFs. A conceptual systems model of residential construction STF risk is presented.

Tear break-up time in eyes with pterygia and pingueculae in Ibadan

Ultraviolet (UV) rays and chronic irritation to dust have been implicated in the pathogenesis of degenerative conditions of the cornea and conjunctiva like pterygium and pinguecula. It has been postulated that exposure to these environmental factors cause corneal and conjunctival drying by disruption of the tear film. While some researchers have found tear film dysfunction in eyes with pterygia and pingueculae, others have found no such abnormalities. The differences in findings may be due to different methods of investigation, or differences based on geography and climate. The tear film has been studied using tear break-up time (TBUT) in adults with pterygia and pingueculae disorders, TBUT was measured in 73 eyes with pterygia and 74 eyes with pinguecula and were compared to TBUT in 74 eyes of age and sex matched normal controls. Abnormal TBUT was defined as TBUT less than 15 secs. Unstable tear film was defined as TBUT less than 10 secs. The mean TBUT was lower in eyes with pterygia (17.90 secs) than in control eyes (19.86 secs), although the mean difference was not statistically significant. Abnormal TBUT, defined as TBUT less than 15 secs, was found in 29 eyes out of 73 eyes with pterygia (39.7%), compared with 13 eyes out of 74 eyes with pingueculae (17.6%) and in 17(23.0%) of 74 control eyes (X2 = 10.01, df = 2, P = 0.0006). A TBUT of less than 15 secs was more significantly associated with eyes with pterygia compared to control eyes. Unstable tear film (TBUT less than 10 secs) was found in 12(16.4%) eyes with pterygia, compared to 4(5.4%) eyes with pingueculae and 4(5.4%) control eyes. Unstable tear film was significantly associated with eyes with pterygia (P = 0.027). Tear film abnormalities are associated with pterygium but not with pinguecula in the subjects studied. TBHT may vary in different populations.

Comparative studies on the activity of basil—an essential oil from Ocimum basilicum L.—against multidrug resistant clinical isolates of the genera Staphylococcus, Enterococcus and Pseudomonas by using different test methods

The essential oil basil is obtained from the aerial parts of Ocimum basilicum L. After gas chromatographic separation, the following components were identified: linalol (54.95%), methylchavikol (11.98%), methylcinnamat (7.24%) and linolen (0.14%). The activity of basil against multidrug resistant clinical isolates from the genera Staphylococcus, Enterococcus and Pseudomonas has been studied. For this purpose, standard and modified broth macrodilution methods were used and time kill kinetic of basil was studied. The minimum inhibitory concentrations (MICs) were reported between 0.0030% and 0.0007% (v/v). These concentrations were compared with the inhibitory concentrations (ICs) and the logs of the bacterial counts reduction both obtained by basil diluted in 1% Tween (Tw) 80, saline test solution (STS) and spiritus vini (Sv) 95° instead in a broth. The data, obtained after application of different methods of investigation and validated with membrane filtration, showed a strong inhibitory effect of basil on the test bacteria. The chosen bacteria are widespread and pose serious therapeutic difficulties because of their high level of resistance. For this reason, the results obtained were considered encouraging.

Photopolymerization Mechanisms and Methods of Investigation

In this document we propose an explanation of the different processes of photopolymerization through different experimentations. Simultaneously we will see different methods of investigation.

Cervical spine lesions after road traffic accidents: a systematic review.

A systematic critical literature review. To determine whether occult pathoanatomical lesions in the cervical spine of road traffic fatalities exist and if they can be identified using optimal autopsy techniques. Previous investigations have examined pathoanatomical conditions of the cervical spine of road traffic fatalities. However, different methods of investigation have been used, and results of studies are conflicting. Hence, potential pathoanatomical conditions in fatalities and survivors remain a controversial issue. Articles were retrieved searching the MEDLINE, Mantis, and Cochrane libraries. Studies examining the cervical spine of road traffic fatalities at autopsy were included and evaluated according to a set of quality criteria. For in-depth review, only studies using surface cryoplaning microtomy autopsy technique and a control group were included. Twenty-seven articles of which three fulfilled the quality criteria were reviewed. In these studies, subtle pathoanatomical lesions were found in the cervical intervertebral discs, cartilaginous endplates, and the articular surfaces and capsules of the zygapophysial joints. The lesions were found exclusively in the traumatized patients and in none of the patients in the control group. Occult pathoanatomical lesions in the cervical intervertebral disc and zygapophysial joints after fatal road traffic trauma may exist. Present imaging methods, especially conventional radiography, do not visualize these subtle lesions; hence, underreporting of pathoanatomical lesions during standard autopsy is probably common. These findings may have clinical relevance in the management of road traffic trauma survivors with potentially similar pathoanatomy.

ALGORITHM FOR THE EVALUATION OF THE SELF-DIFFUSION COEFFICIENT OF SMALL MOLECULES, USING THE NMR MAGNETIC FIELD GRADIENT METHOD

Different methods of investigation of the spin-echo attenuation, in the NMR pulsed field gradient experiments, were analyzed in order to optimize the measurements of the self-diffusion coefficient of the small molecules of simplest liquids. A particular algorithm of representation of the experimental data is proposed in order to eliminate the effect of the residual gradient. This algorithm, tested for pure water, give results in accord with the literature.

Diagnóstico e estadiamento do câncer de pulmão

O câncer do pulmão pode apresentar-se sob diversas formas e vários são os meios de diagnosticá-lo. A escolha do melhor método para o seu diagnóstico depende de diferentes aspectos relacionados ao tumor, ao paciente e à habilidade da equipe médica. Dentre os métodos mais comumente utilizados para o diagnóstico do câncer do pulmão, podemos contar, além dos exames radiológicos, que não serão abordados neste artigo, a citologia do escarro, a broncofibroscopia, a punção aspirativa transtorácica e a toracoscopia, entre outros. O estadiamento reflete a extensão anatômica do câncer. As regras de estadiamento propostas por Denoix foram adaptadas de maneira satisfatória para o câncer do pulmão e, embora tenham sofrido diversas modificações, devidas ao avanço tecnológico dos métodos de diagnóstico, são importantes para orientar o tratamento e estimar o prognóstico. Com o advento de novas modalidades de tratamento, principalmente as combinadas, o estadiamento tende a assumir importância cada vez maior, tanto na escolha da modalidade terapêutica mais adequada quanto na comparação dos resultados.

Behavior of plant tissue in osmotic solutions

The effect of the concentration of sucrose solutions on the cellular structure of potato tissue in equilibrium at 27 °C was studied. Two different methods of investigation were used to determine the volume of the different phases composing the cellular tissue of the potato when in equilibrium with the solutions, one based on data of the concentration itself and the overall volume of 2 mm slices after 48 h at equilibrium, and the other on microscopic images of cells in thin slices of fresh tissue stained with neutral red after an hour in equilibrium to show protoplasts, vacuoles and plasmolysis spaces. The results of these methods were compared with those obtained by a predictive thermodynamic approach considering the semipermeability of cell membranes. Phase volume data obtained from microscopic analysis were more similar to what was predicted by the theoretical model than those obtained by means of composition measurement, where the long equilibrium time apparently led to the loss of semipermeability of the cell membranes, since total volumes calculated without consideration of the cell membranes were similar to those measured. This suggests that the length of time of osmotic dehydration brings about a change in cell structure and the consequent involvement of a different mechanism in mass transfer.

Kinetics of nucleation and growth of zeolite LTA from clear solution by in situ and ex situ XRPD

Investigations on the nucleation and growth processes of Linde type A zeolite (LTA) from clear solution were performed (1) in situ using synchrotron X-ray powder diffraction (XRPD) on small volume samples contained in capillaries, and (2) ex situ using laboratory XRPD on samples synthesized from large volume vessels. Isothermal experiments were performed in the temperature range 60–90 °C. The well known LTA system was selected in order to define the nucleation and growth mechanisms and kinetic parameters, and to critically compare the results of the kinetic analysis obtained by two rather different methods of investigation. The kinetic modeling of the in situ and ex situ isothermal diffraction data indicate that (1) the nucleation mechanisms are the same whether occurring in small-volume or large-volume syntheses; and (2) despite earlier claims of homogeneous nucleation mechanisms, the nucleation process is heterogeneous and invariably involves the formation of an amorphous precursor. All syntheses products associated with zeolite LTA (that is faujasite and hydroxylsodalite type zeolites) have been characterized by XRPD and scanning electron microscopy analyses.

Study of the effect of magnetic field on the structure of Ni-Mn-Ga shape memory alloys

In certain ferromagnetic shape memory Ni-Mn-Ga alloys, the shape changes of the material can be controlled by magnetic field. These changes occur in the martensitic phase and they are result of the martensitic twin boundary motion together with the change of the martensite variants. In the present study, the connection between the magnetisation of the alloys and their martensitic structure was observed by using different methods of investigation. The structure of non-stoichiometric Ni-Mn-Ga alloy was investigated by the optical metallography connected to the optical differential scanning calorimeter (DSC), scanning electron microscopy (SEM) and the X-ray diffraction θ-2θ-analysis. Also, the straining of the materials in dynamic magnetic field was studied. The results of these different investigation methods were in good agreement with each other. However, with the methods in which electron beam was applied to the specimen, it was found that the structure was affected by the research method. The images of martensitic structure obtained with the different methods were compared with each other.

Defect investigation of GaN thin films etched by photo-electrochemical and hot wet etching by atomic force and transmission electron microscopy

ABSTRACTThe availability of reliable and quick methods to investigate defects in GaN films is of great interest. Photo-electrochemical (PEC), and hot wet etching using both H3PO4 acid and molten KOH have been used to study structural defects in GaN layers grown by hydride vapor phase epitaxy and molecular beam epitaxy. The purpose of this work is to determine whether, and under what conditions, these different methods of investigation are consistent and to get to a more accurate estimation of the defect density. As-grown and etched surfaces were investigated by atomic force microscopy (AFM), and plan-view and cross-sectional transmission electron microscopy (TEM). Free-standing whisker-like features and hexagonal etch pits were formed on the etched sample surfaces by PEC and wet etching, respectively. Using plan-view AFM, we found the density of whiskers (8x108-1×109 cm−2) to be similar to the etch pit densities when etched in both H3PO4 and molten KOH under precise etching conditions. During the wet etching process, a careful balance must be struck to ensure that every defect is delineated, but not overetched to cause merging which would lead to an underestimation of the defect density. Additionally, TEM observations confirmed the dislocation densities obtained by etching, which increased our confidence in the consistency of the methods used.