bluuebunny/crossref_metadata_2025 huggingface dataset:
Epigenetic and Chromatin Modifiers As Targeted Therapy of Hematologic Malignancies
Authors: Bhalla Kapil N.
Published: May 2005

Epigenetic regulation of gene expression is mediated through alterations in the DNA methylation status, covalent modifications of core nucleosomal histones, rearrangement of histones, and by RNA interference. It is now abundantly clear that deregulation of epigenetic mechanisms cooperates with genetic alterations in the development and progression of cancer and leukemia. Epigenetic deregulation affects several aspects of tumor cell biology, including cell growth, cell cycle control, differentiation, DNA repair, and cell death. This raises the strong possibility that reversing deregulated epigenetic mechanisms may be an effective treatment strategy for leukemia and cancer. This treatment strategy may either be designed to separately or collectively target the specific perturbations in the epigenetic mechanisms found in human hematologic malignancies. The following review describes our current understanding of the important deregulated epigenetic mechanisms and the preclinical and clinical development of epigenetic and chromatin modifiers in the therapy of these disorders.
The effect of freeze-drying with different cryoprotectants and gamma-irradiation sterilization on the characteristics of ciprofloxacin HCl-loaded poly(D,L-lactide-glycolide) nanoparticles
Authors: Bozdag S , Dillen K , Vandervoort J , Ludwig A
Published: May 2005

In the present study, the influence of freeze-drying with several cryoprotective agents and gamma (γ)-irradiation sterilization on the physicochemical characteristics of ciprofloxacin HCl-loaded poly(D,L-lactide-co-glycolide) (PLGA) nanoparticles was evaluated. Nanoparticles were prepared by W/O/W emulsification solvent evaporation followed by high-pressure homogenization. They were freeze-dried in the presence of 5.0% (w/v) mannitol, trehalose or glucose, with 5.0% (w/v) or 15.0% (w/v) dextran as cryoprotectants. The nanoparticles were irradiated at a dose of 25 kGy using a 60Co source. The following physicochemical properties of the formulations were investigated: the ratio of particle size before (initial) and after freeze-drying, the ease of reconstitution of the nanoparticle suspensions and the drug-release profiles of irradiated and non-irradiated nanoparticles. The anti-bacterial activity against Pseudomonas aeruginosa was measured. The freeze-drying process induced a significant increase in particle size when no cryoprotectant was employed. Similar results were observed when cryoprotectants were added to the formulation. Only when mannitol was used was no significant size increase measured. Moreover, for formulations with dextran, reconstitution after freeze-drying was difficult by manual agitation and particle size could not be determined because of aggregation. After γ-sterilization no significant difference in mean particle size was observed, but reconstitution was more difficult and drug release was influenced negatively. Ciprofloxacin HCl incorporated in the nanoparticles was still effective against the micro-organism selected after freeze-drying and γ-sterilization.
Green tea polyphenols and dietary fibre protect against kidney damage in rats with diabetic nephropathy
Authors: Yokozawa Takako , Nakagawa Takako , Oya Takeshi , Okubo Tsutomu , Juneja Lekh Raj
Published: May 2005

In this study we examined the effect of green tea polyphenols (GTP) and partially hydrolysed guar gum (PHGG) as dietary fibre on diabetic nephropathy, using rats that had been subjected to subtotal nephrectomy and injection of streptozotocin. The subtotally nephrectomized rats were subjected to resection of three-quarters of the kidney. Rats with diabetic nephropathy were divided into four groups: untreated controls, and animals that received GTP (100 mg kg−1 body weight day−1), PHGG (100 mg kg−1 body weight day−1) and GTP plus PHGG (50 mg kg−1 body weight day−1 plus 50 mg kg−1 body weight day−1). After 50 days of administration, attenuation of urinary protein excretion and the morphological changes peculiar to diabetic nephropathy were observed in all three treated groups. Furthermore, the group treated with GTP plus PHGG showed an improvement of kidney weight and serum levels of urea nitrogen, creatinine and creatinine clearance. Hyperglycaemia, as assessed in terms of blood glucose and glycosylated protein levels, was also improved by administration of GTP plus PHGG. On the other hand, GTP administration increased the activity of superoxide dismutase in the kidney to a significant extent. A significant reduction in the total cholesterol concentration was also observed in the PHGG-treated group. These results suggest that GTP and PHGG could be beneficial as additional therapy in the management of diabetic nephropathy.
Forming limit diagrams for single-point incremental forming of aluminium sheet
Authors: Jeswiet J , Young D
Published: May 2005

The single-point incremental forming (SPIF) process is described. The maximum draw angle for SPIF is defined and specific values are given for 3003-0 and 5754-0 aluminium. Forming limit diagrams (FLDs) are developed for incremental forming of aluminium sheet, using SPIF. Five distinct shapes are used to define the forming limits: a hemisphere, a straight-sided cone, a hyperbolic-sided cone, a pyramid, and a shape with five lobes. Strains of more than 300 per cent have been achieved for all shapes.
Influence of proteoglycan contents and of tissue hydration on the frictional characteristics of articular cartilage
Authors: Naka M H , Morita Y , Ikeuchi K
Published: May 2005

In this work, the hypothesis that water content and substances present on the articular surface play an important role in lubrication through the formation of a layer with a high content of water on the articular surface is analysed. The hydrophilic properties of proteoglycans exposed at the articular surface and hydration of tissue are the main responsible factors for the formation of this layer. The role of the articular surface in the frictional characteristics of articular cartilage was examined using specimens (femoral condyles of pigs) with intact and wiped surfaces tested in intermittent friction tests. Results indicated that the intact condition presented low friction in comparison with the wiped condition. The measured water loss of the articular cartilage after sliding and loading indicated a gradual decrease in the water content as the time evolved, and rehydration was observed after the submersion of unloaded specimens in the saline bath solution. Micrographic analyses indicated the presence of a layer covering the articular surface, and histological analyses indicated the presence of proteoglycans in this superficial layer. The hydration of the cartilage surface layer and proteoglycan in this layer influence lubrication.
Design of a stability-detecting device for dental implants
Authors: Huang H-M , Cheng K-Y , Chen C-F , Ou K-L , Lin C-T , Lee S-Y
Published: May 2005

Resonance frequency (RF) analysis technology was used to design a dental implant stability detector. The device uses a miniature-sized electromagnetic triggering rod to elicit vibration in a dental implant. Vibrational signals were recorded via an acoustic receiver. To assess the in vivo performance of the test apparatus, animal models were used. Implants were placed in the left tibia of 12 rabbits using a conventional surgical procedure. Standard 3.2 mm × 8 mm implants were placed in each test tibia with pre-tapping cavities of 3.2 mm and 3.7 mm diameters to simulate either a ‘well-fitting’ or a ‘loosely fitting’ situation. The RF values of the test implants were detected by the newly developed device which was directly mounted on the healing abutments of the implants. The results showed that the RF values of the implants under well-fitting conditions significantly increased (p<0.01) 3 weeks after surgery and reached a plateau at around 6-7 weeks. Meanwhile implants with higher initial RF values had shorter healing times and higher final RF values at the plateau. Based on these findings, it was concluded that the idea of using the current designed device for detecting the degree of bone healing during the osseointegration process seems feasible.
Fabrication and characterization of three-dimensional poly(ether-ether-ketone)/-hydroxyapatite biocomposite scaffolds using laser sintering
Authors: Tan K H , Chua C K , Leong K F , Naing M W , Cheah C M
Published: May 2005

The ability to have precise control over porosity, scaffold shape, and internal pore architecture is critical in tissue engineering. For anchorage-dependent cells, the presence of three-dimensional scaffolds with interconnected pore networks is crucial to aid in the proliferation and reorganization of cells. This research explored the potential of rapid prototyping techniques such as selective laser sintering to fabricate solvent-free porous composite polymeric scaffolds comprising of different blends of poly(ether-ether-ketone) (PEEK) and hydroxyapatite (HA). The architecture of the scaffolds was created with a scaffold library of cellular units and a corresponding algorithm to generate the structure. Test specimens were produced and characterized by varying the weight percentage, starting with 10 wt% HA to 40 wt% HA, of physically mixed PEEK-HA powder blends. Characterization analyses including porosity, microstructure, composition of the scaffolds, bioactivity, and in vitro cell viability of the scaffolds were conducted. The results obtained showed a promising approach in fabricating scaffolds which can produce controlled microarchitecture and higher consistency.
Operability of fast podded RoPax vessels in rough seas
Authors: Sariöz K , Atlar M , Sariöz E , Woodward M D , Sampson R
Published: May 2005

Methods are described for the evaluation of the seakeeping performance of a fast RoPax vessel driven by podded propulsors in the North Sea environment. The evaluation procedure is based on the responses of the vessel in regular waves, the wave conditions encountered, and the limiting values associated with the vessel's mission. The seakeeping performance is represented by the average attainable speed (AAS), which is defined as the ratio of the average speed of the vessel on a specified route to the calm water speed. Both the natural (due to the added wave resistance) and the voluntary (due to the excessive ship responses) speed losses are taken into account. The annual average speed of the fast RoPax design in the North Sea is evaluated and compared with that of a similar size conventional RoPax vessel. The results indicate that, despite its 20 per cent smaller displacement, the fast RoPax design, in general, has better seakeeping performance characteristics than that of the conventional design. The effect of podded propulsors on the average annual speed is also investigated and it is found that the presence of podded propulsors can have favourable effects on the seakeeping performance characteristics, particularly on the vertical plane responses.
Increasing trends in HIV and TB rates in Odessa and the Ukraine
Authors: Drobniewski F , Nikolayevsky V , Asmolov A , Bazhora Yu , Servetsky S
Published: May 2005

Notification rates for HIV and tuberculosis (TB) have increased in the Ukraine and particularly in Odessa. In 1962, the incidence of TB in Odessa region was 178 cases per 100,000 cases, declining to 73.0, 42.0 and 41.6 cases per 100,000 in 1972, 1982 and 1992, respectively. In 2002, TB incidence and prevalence were 80.4 and 330.1/100,000 population, respectively. TB mortality in the port almost doubled from 10.2/100,000 to 21.6/100,000 between 1990 and 2001. In 2002, the HIV incidence and prevalence and AIDS incidence and prevalence were 46.4 and 241.0 cases/100,000 population and 14.5/100,000 and 26.9/100,000, respectively. There are increasing numbers of TB cases co-infected with HIV (200 in 2002), suggesting that the HIV and TB epidemics are converging. Significant effort is needed for the effective control of these two outbreaks to prevent high levels of morbidity and mortality from these diseases.
Low prevalence of high-density lipoprotein cholesterol level < 1 mmol/L in non-nucleoside reverse transcriptase inhibitor recipients
Authors: Bergersen Bente M , Tonstad Serena , Sandvik Leiv , Bruun Johan N
Published: May 2005

Our objective was to compare the prevalence of high-density lipoprotein-cholesterol (HDL-c) level < 1 mmol/L in non-nucleoside reverse transcriptase inhibitor (NNRTI) and protease inhibitor (PI) recipients in an unselected HIV-positive population. All HIV-positive patients living in Oslo who attended our outpatient clinic from April 1, 2000 to April 1, 2001 were invited to a study of cardiovascular risk factors. In this substudy, 40 NNRTI recipients and 124 PI recipients were included. Prevalence of HDL-c <1 mmol/L was 7.5% in the NNRTI recipients compared with 35.5% in the PI recipients ( P <0.001). In the multivariate analyses, use of NNRTI was a significant protective factor (odds ratio [OR] 0.17; 95% confidence interval [CI] 0.05–0.66; P = 0.01) and elevated triglycerides a significant risk factor (OR 3.40; 95% CI 1.47–7.86; P = 0.004) for low HDL-c level. Our study shows that NNRTI recipients have a more favourable HDL-c profile than PI recipients, even when possible confounding factors are taken into account.
CCR2/64I mutation detection in a HIV-1-positive patient with slow CD4 T-cell decline and delay in disease progression
Authors: Burton Catherine T , Gotch Frances M , Imami Nesrina
Published: May 2005

Chemokine receptor genetic mutations are among the factors which have been shown to influence human susceptibility to HIV-1 infection and progression. The CCR2-64I mutation has been shown to delay HIV-1 disease progression in some studies. Here we show evidence of delayed disease progression, reflected in maintenance of a stable viral load and a slow CD4 T-cell decline, in a patient with the CCR2-64I gene. We then consider the potential value of identifying these genetic defects in the era of fusion/entry inhibiting therapeutics.
The adherence to antiretroviral treatment evaluated from a hospital pharmacy: importance of the protease inhibitors pharmacological class
Authors: Rubio M , Pédeboscq S , Ekouevi D , Zalabadi K , Chêne G , Bonarek M , Pometan J P
Published: May 2005

The goal of this study was to develop an evaluation method of antiretroviral treatment adherence from a hospital pharmacy and to identify one or more factors that influenced this adherence, such as patient or treatment characteristics.

The HIV patients included in this study were based, for the major part, in Saint-André hospital and collected their medication from this hospital pharmacy. They were all delivered a renewable prescription that should have comprised two successive delivery stamps. A total of 186 patients was included. For the adherence analysis, the delay between two successive deliveries was measured.

We have specified three different categories of patients: adherent, non-adherent and intermediate, according to a definition of adherence accepted by many authors.

We have demonstrated that the only antiretroviral therapeutic class associated with poor adherence was the protease inhibitors, in particular nelfinavir, which requires food to be taken at the time of administration. This can pose difficulties for those patients who lunch at their workplace and consequently affect adherence.

This study allowed us to demonstrate that a less subjective adherence evaluation can be easily carried out from a hospital pharmacy.
Concurrent gonococcal and chlamydial infections among men attending a sexually transmitted diseases clinic
Authors: McMillan A , Manavi K , Young H
Published: May 2005

The aim of this retrospective study was to determine the prevalence of Chlamydia trachomatis co-infection in men with gonorrhoea attending a sexually transmitted diseases clinic in Edinburgh, Scotland. During the study period, there were 660 cases of culture-proven gonorrhoea. Chlamydial DNA was detected in the urethra in 79 (31%; 95% confidence interval [CI], 25–37%) heterosexual men who have sex with women (MSW); the median age was significantly lower than those with gonorrhoea alone (24.0 versus 30.0; P < 0.0005). The prevalence of urethral chlamydial infection among MSW was significantly higher than among men who have sex with men (MSM) (32 [12%; 95% CI, 8–16%] of 268 MSM) (χ2 = 27.21; P < 0.001). Sixteen (24%; 95% CI, 14–34%) of 68 MSM with rectal gonorrhoea had concurrent rectal chlamydial infection. The high prevalence of concurrent gonorrhoea and chlamydiae therefore warrants empirical treatment and/or testing for chlamydia in all men with urethral gonorrhoea.
Efficacy of interventions in improving adherence to antiretroviral therapy
Authors: Côté José K , Godin Gaston
Published: May 2005

The aim of this paper is to perform a critical review of the effectiveness of interventions for the purpose of enhancing adherence to antiretroviral therapy. The overall evaluation indicates that research is in its early stages. Although pilot studies provide support for the feasibility of their protocols, and preliminary results also suggest their capacity to improve adherence, only three major trials have reported significant improvement in adherence. The issues that will have to be addressed by future studies include: (a) the need for a theoretical and empirical understanding of the phenomena; (b) adoption of a format that fits the attributes of the population; (c) the use of multiple strategies involving key providers; (d) a concise and precise schedule governing the frequency and intensity of the intervention; (e) a careful selection of direct outcome; and (f) appropriate time measurement. In sum, greater efforts to design and evaluate interventions are needed to lead to an increase in adherence and improvement in treatment effectiveness.
Acceptance of flexible sigmoidoscopy and colonoscopy for screening and surveillance in colorectal cancer prevention
Authors: Nicholson Fiona B , Korman Melvyn G
Published: May 2005

Objectives: To study an individual's experience of either flexible sigmoidoscopy (FS) or colonoscopy in a colorectal cancer prevention programme.

Methods: Consecutive individuals in a Bowel Cancer Prevention Programme, who had either an unsedated FS or a colonoscopy with sedation, participated in a prospective cross-sectional questionnaire-based study.

Results: A total of 447 responses were obtained for 256 colonoscopies and 191 FSs (200 men [45%] and 247 women [55%]). The overall experience of colonoscopy was more comfortable than FS (75% versus 18%; P<0.001). Embarrassment was low for both procedures (8%). There was no pain associated with colonoscopy and most individuals had a pain score of less than 3 (11-point scale) for FS: 72% of men, 55% of women ( P<0.001). Most individuals did not have a gender preference for the endoscopist. For colonoscopy, the worst part of the procedure was the preparation (78%) and for FS the preparation and the procedure ranked equally worst (30%).

Conclusions: We have shown that colonoscopy with sedation is a very comfortable procedure. FS is more uncomfortable than colonoscopy; however, for the majority it is a tolerable experience. Women found FS only slightly more painful than men. The worst part of either procedure was the preparation. Embarrassment with either procedure was minimal. Both procedures are well tolerated and suitable for colorectal cancer screening.
The prevention of neonatal group B streptococcal disease: a report by a working group of the Medical Screening Society
Authors: Law MR , Palomaki G , Alfirevic Z , Gilbert R , Heath P , McCartney C , Reid T , Schrag S
Published: May 2005

Streptococcus agalactiae, or Lancefield group B streptococcus (GBS), is the most frequent cause of serious bacterial sepsis, including neonatal meningitis, in UK neonates. Early-onset neonatal GBS infection, but not late-onset, can be prevented by screening to identify high-risk pregnancies and administering penicillin during delivery. A vaccine has been developed as an alternative means of prevention but it is awaiting a randomized trial before being available for general use. In this review we examine the published literature to assess the morbidity and mortality attributable to neonatal GBS infection, quantify the screening performance of the two alternative modes of screening (microbiological and risk factor based), review the evidence on the efficacy of the vaccine, and estimate the numbers of deaths and cases of serious disability that each strategy in turn might prevent in the UK, in order to assess the most effective means of prevention for the UK.
Herbal Therapy in Primary Health Care in Maracanaú, Ceará, Brazil
Authors: Silva Maria IG , Sousa Francisca CF , Gondim Ana PS
Published: May 2005

BACKGROUND

The public health system in Brazil is insufficient to provide basic pharmaceutical and medical care to the population. Currently, some herbal therapy programs are being developed in primary healthcare services to supply the communities lacking basic medicines.

OBJECTIVE

To investigate the use of herbal medicines in primary health care in Maracanaú, a northeast Brazilian city.

METHODS

A descriptive cross-sectional study was conducted in family health care units in Maracanaú during August and September of 2002. Two hundred twenty-six patients were interviewed via structured questionnaire. Descriptive statistical analysis was accomplished using sample size and proportions. χ 2 And Student's t-tests were used to compare percentages and means, respectively.

RESULTS

Among the 226 patients interviewed, 144 (63.7%) reported previous use of herbal medicines. Among those, 131 (90.9%) observed therapeutic benefits from herbal medicines. We identified 10 types of herbal medicines in the prescriptions, including syrups, dyes, capsules, and ointments, for the treatment of respiratory problems (63.8%), skin conditions (15.3%), diabetes mellitus (11.4%), and other illnesses. Further, we observed that some herbal medicines were not being produced during the study period and that several patients were not aware of the fact that they were receiving herbal medicine.

CONCLUSIONS

Data support the use of herbal therapy in primary health care in Maracanaú. However, there is a need to conduct further study on the efficacy and safety of these herbal medicines, as well as on their quality control.
Interpretation of Medication Pictograms by Adults in the UK
Authors: Knapp Peter , Raynor David K , Jebar Adel H , Price Sarah J
Published: May 2005

BACKGROUND

Patients' ability to understand information about medication is crucial for safety and effectiveness. Rates of illiteracy worldwide indicate that written information alone cannot meet many patients' needs. Medication pictograms are an alternative, but may be culturally sensitive. Previous testing has used large pictograms, which are impractical for conventional drug information formats.

OBJECTIVE

To compare 2 sets of pictograms for instructions or warnings (from the US and South Africa) for understandability by adults in the UK and examine the effects of pictogram size and repeat presentation on understandability among older adults.

METHODS

In the first part of the study, 160 adults (aged 17–83 y) reviewed and interpreted 10 pictograms. In the second, 67 older adults (aged 65–96 y) were randomly assigned to review 10 small or large pictograms. After giving their interpretation, they were informed of the correct meaning. One week later, they were shown the same pictograms and gave their interpretation.

RESULTS

The pictograms for the 10 different instructions and warnings showed great variation in interpretation rates (7.5–90%), with few significant differences between the US and South African versions. Only 3 were understood by ≥85% of the population. Pictograms performed significantly better if they were larger and at the second presentation.

CONCLUSIONS

Pictograms have the potential to help patients understand information on drug therapy. This study shows that some existing pictograms are not easily interpreted and that testing is needed before their implementation. A reduction in their size to allow incorporation into conventional written formats may cause additional problems for patients.
Risk Factors for Adverse Drug Events: A 10-Year Analysis
Authors: Evans R Scott , Lloyd James F , Stoddard Gregory J , Nebeker Jonathan R , Samore Matthew H
Published: May 2005

BACKGROUND

Many adverse drug events (ADEs) are the result of known pharmacologic properties, and some result from medication errors. However, some are the result of patient-specific risk factors.

OBJECTIVE

To identify inpatient risk factors for ADEs.

METHODS

Conditional logistic regression was used to analyze all pharmacist-verified ADEs by therapeutic class of drugs and severity during a 10-year study period. All inpatients ≥18 years of age from a 520-bed tertiary teaching hospital were included. Each case patient was matched with up to 16 control patients. Odds ratios for patient factors associated with ADEs were calculated from different therapeutic classes of drugs.

RESULTS

Odds ratios for numerous risk factors were identified for 4376 ADEs and were found to vary depending on therapeutic classification. The risk factors for the different classifications were grouped by (1) patient characteristics—female (OR 1.5–1.7), age (0.7–0.9), weight (1.2–1.4), creatinine clearance (0.8–4.7), and number of comorbidities (1.1–12.6); (2) drug administration—dosage (1.2–3.7), administration route (1.4–149.9), and number of concomitant drugs (1.2–2.4); and (3) patient type—service (1.2–4.9), nursing division (1.5–3.8), and diagnosis-related group (1.5–5.7).

CONCLUSIONS

Some risk factors are consistent for all ADEs and across multiple therapeutic classes of drugs, while others are class specific. High-risk agents should be closely monitored based on patient characteristics (gender, age, weight, creatinine clearance, number of comorbidities) and drug administration (dosage, administration route, number of concomitant drugs).
Polytype and Morphology Analyses of Kaolin Minerals by Electron Back-Scattered Diffraction
Authors: Kogure Toshihiro , Inoue Atsuyuki , Beaufort Daniel
Published: May 2005

The electron back-scattered diffraction (EBSD) technique has been applied to fine-grained kaolin minerals to determine the polytypes (kaolinite, dickite and nacrite) of individual grains and their crystallographic orientations in a scanning electron microscope (SEM). Because kaolin minerals are prone to radiation damage by the intense electron beam necessary to obtain EBSD patterns, the beam has to be rastered across the specimens during pattern acquisition. Kaolinite-dickite and nacrite are easily distinguished by their trigonal or hexagonal symmetry about the [001]* direction, respectively, of the Kikuchi bands with k = 3n. Dickite can be differentiated from kaolinite by mirror symmetry parallel to the a-c plane, and by the characteristic contrast of HOLZ rings.

As EBSD analysis is performed using a SEM, morphological characters can be correlated with polytypes. Dickite fragments could be discerned as oriented overgrowths on nacrite plates. Dickite was observed to always adopt euhedral shapes in a diagenetic mixture of kaolinite and dickite. Lath-shaped dickite is elongated along the a axis direction. Rhombohedral dickite consists of crystals with {1̄11} indexed to the side facets.
Fabric Map for Kaolinite: Effects of pH and Ionic Concentration on Behavior
Authors: Palomino Angelica M. , Santamarina J. Carlos
Published: May 2005

The behavior of fine-grained mineral systems is dependent on pore-fluid characteristics. The systematic analysis of previously published studies supports the development of a fabric map in the pH and ionic concentration space as a working hypothesis. This conceptual study is complemented with an extensive battery of tests where surface charge and particle interactions are controlled through pore-fluid characteristics. The macro-scale tests include sedimentation, viscosity and liquid limit, and involve a wide range of solid volume fractions (suspension to sediment) and strain levels. Experimental results permit the development of an updated fabric map on the pH-ionic concentration space which takes into consideration all experimental results. The fabric map is structured around a critical pH level and a threshold ionic concentration beyond which van der Waals attraction prevails.
Clay Mineralogy and Chemical Composition of Bentonites from the Gourougou Volcanic Massif (Northeast Morocco)
Authors: Ddani Mohamed , Meunier Alain , Zahraoui Mohamed , Beaufort Daniel , El Wartiti Mohamed , Fontaine Claude , Boukili Boubker , El Mahi Benacer
Published: May 2005

The Gourougou volcanic massif (northeastern Morocco) is actively prospected for bentonite deposits. Five bentonites originating from different environments were selected for the present study: hydrothermal alteration of obsidian perlite glass inside the volcanoes themselves (Providencia and Tribia deposits); alteration of pyroclastic flows in a marine shallow water to lagoonal lacustrine environment (Ibourhardayn deposit); ash falls in marine or lacustrine systems (Moulay Rachid and Melg el Ouidan (formerly Camp Berteau) deposits). All of these bentonites were probably formed from volcanic glass originating from a rhyolitic magma at different stages of differentiation as shown by slight variations of REE and incompatible element abundances. The crystal-chemical characteristics of the smectite vary according to alteration conditions: beidellite predominates in hydrothermal systems, whereas montmorillonite predominates in lagoonal and lacustrine environments, and mixed-layer beidellite-montmorillonite in the sea-water-altered pyroclastic flows. All these dioctahedral smectites exhibit a heterogeneous distribution of charge as shown by the presence of partially expandable (1 EG) or non- expandable (0 EG) layers in the K-saturation state. The proportion of the collapsed or partially expandable layers is not related to the average layer charge or to the cation exchange capacity. This militates for an overall heterogeneous charge distribution. Compared to other natural or experimental alteration systems of similar rhyolitic glass, the formation of beidellite or montmorillonite appears to be controlled by the amounts of Mg in the system.
Castor Toxin Adsorption to Clay Minerals
Authors: Jaynes William F. , Zartman Richard E. , Green Cary J. , San Francisco Michael J. , Zak John C.
Published: May 2005

The extremely toxic protein, ricin, is derived from castor beans and is a potential terrorist weapon. Adsorption to clays might minimize the environmental persistence and toxic effects of this toxin. Ricin adsorption to clay minerals was measured using batch adsorption isotherms. Enzyme-linked immunoassay methods were used to quantify aqueous ricin concentrations. Montmorillonite, sepiolite and palygorskite effectively adsorbed ricin from aqueous solutions and yielded mostly Langmuir-type isotherms. The monolayer adsorption capacity from a Langmuir equation fit at pH 7 was 444 g ricin/kg for montmorillonite (SWy-2), but was only 5.6 g ricin/kg for kaolinite (KGa-1b). Monolayer capacities for sepiolite (SepSp-1) and palygorskite (PFl-1) at pH 7 were 59.2 and 58.1 g ricin/kg. The high-charge montmorillonite (SAz-1) effectively adsorbed ricin at pH 7, but yielded a linear isotherm with K = 5530 L/kg. At pH 5, both montmorillonites (SWy-2 and SAz-1) yielded Langmuir-type isotherms with monolayer capacities of 694 and 641 g ricin/kg. Clay samples with higher cation exchange capacities generally adsorbed more ricin, but adsorption also followed specific surface area. X-ray diffraction of <2 μm SWy-2 treated with 470 g ricin/kg indicated expansion up to 34.6 Å at buffered pHs of 4 and 7, but not at pH 10. Furthermore, ricin adsorption was greatest at pH 4 and 7, but minimal at pH 10. Treatment with 1.41 kg of purified ricin/kg clay at pH 5 yielded a 35.3 Å peak and adsorption of ~1.2 kg ricin/kg. Similar treatment with lower-purity ricin yielded less expansion and lower adsorption. The 35.3 Å peak interpreted either as a d002 or d001 reflection indicates a 70.6 Å or a 35.3 Å ricin/SWy-2 complex. This implies that adsorption and air drying have compressed interlayer ricin molecules by 18 to 65%. Effective ricin adsorption by montmorillonite suggests that it could be used to minimize the toxic effects of dispersed ricin.
Uranyl Surface Complexes in a Mixed-Charge Montmorillonite: Monte Carlo Computer Simulation and Polarized XAFS Results
Authors: Greathouse Jeffery A. , Stellalevinsohn Hannah R. , Denecke Melissa A. , Bauer Andreas , Pabalan Roberto T.
Published: May 2005

We report a combined experimental and theoretical study of uranyl complexes that form on the interlayer siloxane surfaces of montmorillonite. We also consider the effect of isomorphic substitution on surface complexation since our montmorillonite sample contains charge sites in both the octahedral and tetrahedral sheets. Results are given for the two-layer hydrate with a layer spacing of 14.58 Å. Polarized-dependent X-ray absorption fine structure spectra are nearly invariant with the incident angle, indicating that the uranyl ions are oriented neither perpendicular nor parallel to the basal plane of montmorillonite. The equilibrated geometry from Monte Carlo simulations suggests that uranyl ions form outer-sphere surface complexes with the [O=U=O]2+ axis tilted at an angle of ~45° to the surface normal.
Compact Raman Spectrometers: Data Handling Methods
Authors: Vickers Thomas J. , Rosen Christopher A. , Mann Charles K.
Published: May 2005

Measurements have been made on a compact dispersive Raman spectrometer of the type often proposed for on-line measurements. Quantitative use of the details of spectra that are produced by this system require different data treatments than those which have been described for longer-focal-length instruments. The data sets are sparsely sampled, and they cover a wide spectral window. Owing to sparse sampling, spectra as recorded have the appearance of piecewise linear approximations. It is necessary to interpolate additional data points in order to observe details of peaks, such as exact positions of maxima. With wider spectral windows, procedures for calibration of the wavenumber axis which have been previously described do not meet our performance criterion: an accuracy of 0.1 cm−1 or better. A model that involves a fifth-order polynomial is needed. On the basis of the performance of this model, atomic lines which give satisfactory results when used as wavenumber references have been identified. Details of a self-modeling procedure for removal of broad-band spectral interferences are described, and its performance is demonstrated.
Improvement in Fourier Near- and Mid-Infrared Diffuse Reflectance Spectroscopic Calibrations through the Use of a Sample Transport Device
Authors: Reeves James B.
Published: May 2005

The objective of this research was to determine whether diffuse reflectance calibrations using a Fourier transform spectrometer (FTS) could be improved by increasing the scanned sample area. A linear motion sample transport (TRANSCELL) was attached to the FTS, which increased the area scanned from 2 mm in diameter (stationary cell or STATCELL) to 2 × 50 mm. Sodium chlorite-treated forages and by-products ( N = 174) were scanned in the near-infrared (NIR) and mid-infrared (MIR) with the use of the TRANSCELL and STATCELL. Samples were analyzed for fiber, digestibility, lignin, protein, and lignin nitrobenzene oxidation products (NOPs). Overall, the best results for fiber, lignin, and digestibility were achieved by using MIR spectra and the TRANSCELL. Results in the NIR (FTS) with the use of the TRANSCELL were also improved over those obtained with the STATCELL. While the TRANSCELL was an improvement over the STATCELL for Fourier NIR analysis of NOPs, in the MIR, results for NOPs were about equal for the TRANSCELL and STATCELL. In conclusion, the use of a TRANSCELL can improve calibrations from Fourier transform spectrometers, although the degree of improvement depends on the spectral region and specific calibration under study.
Characteristic Vibrational Pattern for the Cyclic Dimer Carboxylic Acid Function in the Solid State
Authors: Wolfs Ilse , Desseyn Herman O.
Published: May 2005

The infrared and Raman characteristics of the cyclic dimer hydrogen-bonded carboxylic acid function in the solid state are fully reported. Some dicarboxylic acids (e.g., malonic, methylmalonic, di-methylmalonic, succinic, glutaric, and adipic acid) are reported as typical examples. The vibrational characteristics of the cyclic dimer hydrogen-bond pattern are studied through the effect of deuteration on the position of infrared and Raman bands and through the temperature effect on the behavior of the vibrational bands. The fundamentals can very well be compared with the fundamentals of the trans secondary amide function, and are therefore assigned as the acid I to acid VII fundamentals.
Use of Normalized Relative Line Intensities for Qualitative and Semi-Quantitative Analysis in Inductively Coupled Plasma Atomic Emission Spectrometry Using a Custom Segmented-Array Charge-Coupled Device Detector. Part II: Applications to Qualitative Analysis with Line-Rich Matrices
Authors: Rivier Cedric , Mermet Jean-Michel
Published: May 2005

In a previously published work, a procedure was described to conduct qualitative analysis in inductively coupled plasma atomic emission spectrometry, keeping in mind the possibility of spectral interferences. This procedure is based on the use of both line correlation and normalized relative line intensities of given elements. When spectral interferences due to a single or two major elements are observed for an analyte, use of multiple linear regression of the normalized relative line intensities of both the analyte and the major element provides information about the certainty of the presence of the analyte. This procedure has been used with an echelle grating-based dispersive system equipped with a custom segmented-array charge-coupled device detector and evaluated with the use of line-rich matrices such as Fe, Cr, and Ni. Satisfactory results were obtained even when several lines of the analyte suffered from interference. The only limitation was the number of available lines for a given analyte.
Spectroscopy of Hydrothermal Reactions III: The Water—Gas Reaction, “Hot Spots”, and Formation of Volatile Salts of NCO− from Aqueous [NH3(CH2)nNH3]NO3 (n = 2, 3) at 720 K and 276 Bar by T-Jump/FT-IR Spectroscopy
Authors: Maiella P. G. , Brill T. B.
Published: May 2005

Strongly exothermic reactions raise fundamental and practical questions about the use of hydrothermal reactions to destroy hazardous materials. The decomposition products of ethylenediammonium dinitrate, which is close to oxygen balance, are compared by IR spectroscopy after flash heating under 69–276 bar in Ar and in the presence of excess H2O and H2. The occurrence of the water–gas shift reaction was confirmed by changes in the CO/CO2 ratio. This reaction sets the final CO/CO2 ratio at the “freeze-out” temperature, whose magnitude (1300–1470 K) raises concern about potential formation of “hot spots” in the reaction stream should solid particles of the explosive exit. IR absorbances at 2168 and 2193 cm−1 are also observed when flash decomposition of the propylene homolog occurs in the presence of H2O. These absorbances lie in the range of the explosive fulminate group. It was found, however, that these absorbances result instead from vaporized H3O+NCO−and NH4+NCO− aggregates. Consequently, in addition to contributing to the water–gas shift reaction, H2O opens an isocyanate decomposition channel which has a minimal role without H2O.
Copper Binding to Bilirubin as Determined by FT-IR and EPR Spectroscopy
Authors: Ferraro J. R. , Wu J.-G. , Soloway R. D. , Li W.-H. , Xu Y.-Z. , Xu D.-F. , Shen G.-R.
Published: May 2005

Copper is known to form complexes with bilirubin (H2BR). Such complexes have received increased attention because of their clinical significance as free-radical scavengers. The purpose of this study was to examine a series of Cu2+ BR complexes to ascertain the nature of the binding between Cu2+ and BR. Several physical measurements of the salts were made, such as Fourier transform infrared (FT-IR) and electron paramagnetic resonance (EPR). The complexes were prepared by dissolving protonated BR in NaOH and adding different ratios of aqueous CuCl2. At ratios of Cu2+/H2BR of 1:1 and 2:1, soluble complexes were formed. In solution, EPR spectra demonstrated nine hyperfine peaks, which, from the splitting, is indicative of Cu2+ coordinated to four nitrogen atoms coming from two molecules of BR. The solid obtained from the solutions demonstrated predominant infrared absorptions at 1574 and 1403 cm−1 (previously assigned as COO− vibrations, asymmetric and symmetric), whereas the 1710-cm−1 vibration appears only as a shoulder (previously assigned as the free COOH vibration), indicative that most of the COO− groups have reacted with sodium, thus accounting for the aqueous solubility. The NH stretching vibration in the pyrrole group of H2BR has disappeared and is replaced with the OH stretching vibration in H2O. At higher ratios of 3:1 and 5:1 (Cu2+/H2BR), black precipitates are formed, which produce no EPR signals. Furthermore, the NH vibration disappears as in the soluble solution complexes. It can be concluded that the insoluble salts (higher Cu2+/H2BR ratios) are mixed complexes containing the Cu–nitrogen chelate and Cu salts involving the COOH groups.
Aotfs as Atomic Spectrometers: Basic Characteristics
Authors: Fulton Greg , Horlick Gary
Published: May 2005

An electronic spectrometer based on an acousto-optic tunable filter (AOTF) is presented. These devices are electronically tunable, narrow-band light filters with no moving parts. The wavelength range from 350 to 600 nm can be covered with a single device, the entire spectrum is scanned in less than 1 s, and any wavelength can be randomly accessed in 0.1 ms. The resolution [full width at half-height (FWHH)] was determined to be 0.22 nm at 361 nm, and the standard deviation of peak position was usually less than 0.03 nm. Under software control, the AOTF can be stationary on a line, peak-hop between any 20 different lines, hop between 20 regions of any size, scan a spectrum, or operate as a wavelength modulation spectrometer. Operation of the spectrometer is illustrated by using hollow cathode and inductively coupled plasma atomic emission sources.
Scanning Tunneling Microscope Images of Graphite Substrates Used in Graphite Furnace Atomic Absorption Spectrometry
Authors: Vandervoort Kurt G. , Butcher David J. , Brittain Chris T. , Lewis Benji B.
Published: May 2005

Scanning tunneling microscopy (STM) was used to elucidate the submicrometer defect structures on the graphite substrates used in graphite furnace atomic absorption spectrometry (GFAAS). Images were obtained on pristine pyrolytic coated and uncoated polycrystalline graphite tubes and on pure pyrolytic graphite platforms. For comparison, images of highly oriented pyrolytic graphite, not used in GFAAS, were also obtained. Polycrystalline tubes were characterized by disordered surfaces with extensive oxidation. Pyrolytic coated tubes and pure pyrolytic graphite platforms were characterized by scaled structures, island columns, or smoothly varying contours. Scaled structures and island columns presented the greatest abundance of exposed carbon edge sites and seemed probable areas for analyte reactivity and intercalation. In areas displaying smoothly varying contours, atomic imaging revealed basal plane surface layers with moderate curvature but regular spacing between the carbon atoms within the layers. The results imply that the weak ordering between graphite layers along the c-axis does not preclude good atomic ordering within the layers, and this factor may be sufficient for discouraging analyte—substrate interactions.
Determination of Weight Percent Oxygen in Commercial Gasoline: A Comparison between FT-Raman, FT-IR, and Dispersive Near-IR Spectroscopies
Authors: Cooper John B. , Wise Kent L. , Welch William T. , Bledsoe Roy R. , Sumner Michael B.
Published: May 2005

The weight percent oxygen in commercial gasoline samples has been determined by using partial least-squares (PLS) regression analysis combined with either FT-Raman, FT-IR, or dispersive near-IR spectroscopy. Calibration models were constructed with the use of 33 MTBE oxygenated commercial gasolines. The minimum standard errors of validation with the use of leave-one-out validation are 0.156, 0.188, and 0.119 wt % oxygen for FT-Raman, FT-IR, and near-IR, respectively. An independent test set of 36 MTBE oxygenated commercial gasolines was used to further validate the PLS models. The minimum standard errors of prediction for the test set are 0.155, 0.143, and 0.131 wt % oxygen for FT-Raman, FT-IR, and near-IR, respectively. The wt % oxygen in all samples ranges from 0.2 to 3.262%.
Simplified and Efficient Method of Computing Generalized Two-Dimensional Correlation Spectra
Authors: Burie Jean-René
Published: May 2005

A very powerful generalized two-dimensional correlation method applicable to various types of spectroscopy involving signals dependent on various physical variables (e.g., time) was recently developed and reported. In order to obtain an easy computational procedure, the effect of the practical limitation of the data along the time axis to N is considered. This information gives rise to a new formula for the disrelation spectrum. This modified disrelation spectrum is shown to still be useful in the differentiation of overlapping peaks, even when N is small.
In situ Near-IR Cure Monitoring of a Model Epoxy Matrix Composite
Authors: Cossins Sheryl , Connell Mike , Cross Bill , Winter Robb , Kellar Jon
Published: May 2005

To improve the performance of composites it is imperative that the interphase region between the inorganic reinforcement and the polymer matrix be more completely understood. It is in this region that the stress transfer between the matrix and the reinforcement occurs. To this end, the curing of epoxy adjacent to an embedded silica optical fiber has been monitored in situ by evanescent wave spectroscopy. The epoxy studied is partially fluorinated and has a lower refractive index than the silica optical fiber. This combination of epoxy/silica served as a model composite system. The lower refractive index of the partially fluorinated epoxy allowed the silica optical fiber to be used as a waveguide for the internal reflection of near-infrared light. The epoxy curing was determined as a function of time and temperature by analysis of the near-infrared spectrum from the epoxy adjacent to the fiber obtained by the interaction of the evanescent wave that occurs at each internal reflection with the low-refractive-index epoxy. The results obtained from the examination of the near-infrared spectrum, particularly the disappearance of the NH2 stretching/bending combination band at ∼4925 cm−1 and the concomitant increase of the C–N overtone band at ∼4725 cm−1, showed that epoxy ring-opening and cross-linking reactions could be followed in real time. Finally, treatment of the fiber with a silane coupling agent had no observable effect on the curing reaction of the epoxy.