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PubMedDate not supplied

Evaluation of the mixed aggregate method as an alternative to the bismuth active substances and cobalt thiocyanate active substances procedures for the determination of nonionic surfactants in raw and treated sewage.

The mixed aggregate (MA) method was evaluated for the routine determination of total ethoxylated nonionic surfactants in municipal raw and treated sewage. Nonionics in wastewater samples were enriched with a C8 solid-phase extraction cartridge, eluted with ethyl acetate-methanol, and separated from interferences with stacked strong anionic (quaternary ammonium form) and cationic (benzenesulfonic acid form) exchange columns. Sample extracts were evaporated to dryness and redissolved in distilled water. The total amount of ethoxylates, on a weight basis, was determined by measuring the critical micelle concentration of a mixed micelle made up of ethoxylates and the anionic surfactant sodium dodecyl sulfate, used as the reagent. The dye Coomassie Brilliant Blue G was used as a photometric probe. The minimum amount of ethoxylate required for a single determination was 1 microg. For raw sewage samples, mean recoveries and standard deviations were 98 +/- 6 and 98 +/- 4% at fortification levels of 0.3 and 0.6 microg/mL, respectively. For treated sewage samples, mean recoveries and standard deviations were 95 +/- 2 and 100 +/- 2% at fortification levels of 0.03 and 0.06 microg/mL, respectively. The MA method and the classical bismuth active substances and cobalt thiocyanate active substances procedures were compared. The former offers some significant advantages over the classical procedures in terms of sensitivity, selectivity, precision, simplicity, and rapidity; the type of response is independent of both the molecular weight and the chain length of the surfactant.

Algorithms↗

PubMed2003

Evaluation of microbial source tracking methods using mixed fecal sources in aqueous test samples.

Microbiological source tracking (MST) methods are increasingly being used to identify fecal contamination sources in surface waters, but these methods have been subjected to limited comparative testing. In this study, 22 researchers employing 12 different methods were provided sets of identically prepared blind water samples. Each sample contained one to three of five possible fecal sources (human, dog, cattle, seagull or sewage). Researchers were also provided with portions of the fecal material used to inoculate the blind water samples for use as library material. No MST method that was tested predicted the source material in the blind samples perfectly. Host-specific PCR performed best at differentiating between human and non-human sources, but primers are not yet available for differentiating between all of the non-human sources. Virus and F+ coliphage methods reliably identified sewage, but were unable to identify fecal contamination from individual humans. Library-based isolate methods correctly identified the dominant source in most samples, but also had frequent false positives in which fecal sources not in the samples were incorrectly identified as being present. Among the library-based methods, genotypic methods generally performed better than phenotypic methods.

Adenoviridae↗

PubMed2000

Best number, best mix, best method.

Learn the Joint Commission's requirements for staffing levels and skill mix and how surveyors determine if your organization measures up.

Clinical Competence↗

PubMed2002

A throughfall collection method using mixed bed ion exchange resin columns.

Measurement of ionic deposition in throughfall is a widely used method for measuring deposition inputs to the forest floor. Many studies have been published, providing a large database of throughfall deposition inputs to forests. However, throughfall collection and analysis is labor intensive and expensive because of the large number of replicate collectors needed and because sample collection and chemical analyses are required on a stochastic precipitation event-based schedule. Therefore we developed and tested a throughfall collector system using a mixed bed ion exchange resin column. We anticipate that this method will typically require only one to three samplings per year. With this method, bulk deposition and bulk throughfall are collected by a funnel or snow tube and ions are retained as the solution percolates through the resin column. Ions retained by the resin are then extracted in the same column with 2 N KCl and analyzed for nitrate and ammonium. Deposition values in throughfall from conventional throughfall solution collectors and colocated ion exchange samplers were not significantly different during consecutive 3- and 4-month exposure periods at a high (Camp Paivika; >35 kg N ha(-1) year(-1)) and a low deposition (Barton Flats; 5-9 kg N ha(-1) year(-1)) site in the San Bernardino Mountains in southern California. N deposition in throughfall under mature pine trees at Camp Paivika after 7 months of exposure was extremely high (87 and 92 kg ha-1 based on the two collector types) compared to Barton Flats (11 and 13 kg ha(-1)). A large proportion of the N deposited in throughfall at Camp Paivika occurred as fog drip, demonstrating the importance of fog deposition as an input source of N at this site. By comparison, bulk deposition rates in open areas were 5.1 and 5.4 kg ha(-1) at Camp Paivika based on the two collector types, and 1.9 and 3.0 kg ha(-1) at Barton Flats.

Ammonia↗

PubMedDate not supplied

Some remarks of penicillin and desacetylcephalosporin synthesis by mixed anhydrides method.

The possibilities of 6-APA and 7-ADCA acylation by means of mixed anhydrides from ethyl chloroformate and cyclic carboxylic acids were investigated. The complexity of acylation course was observed, which depends upon kind of aminoderivative and structure of starting acid, respectively. In the case of mixed anhydrides formed from acid derivatives of which vicinal carbon atoms of ethylene bond built on into appropriate cyclic system were connected with methyl and carboxylic group (-C)CH3=C(COOH(-), it was found, that the main reaction products were: the suitable ureids and ethoxypenicillin or ethoxydesacetylcephalosporin. After treatment of 6-APA or 7-ADCA with different esters of chloroformic acid the corresponding alkoxy-, aralkoxy- or aryloxyderivatives were obtained. The MIC estamination showed, that only penicillin derivatives may be considered as interesting microbicides.

Acylation↗

PubMed1984

A comparison of the cyclic anhydride and mixed anhydride methods for 111In-DTPA chelation to monoclonal antibodies.

The cyclic anhydride (CA) and the mixed anhydride (MA) of DTPA were synthesized and used to chelate 111In to an antimelanoma monoclonal antibody. The CA and MA methods showed mean labeling efficiencies of 25.7 and 20.5%, respectively (p = NS). The binding efficiency of labeled antibody to human melanoma cells in tissue culture also was similar (means = 52 and 50%, respectively, p = NS), as was tumor uptake in nude mice at 96 hrs post-injection (16%-CA vs 12%-MA). The method required less complicated chemical syntheses, much less preparation time, and the product was stable over a much longer period. The results suggest that the CA method is preferable for bifunctional chelate labeling of monoclonal antibodies with 111In-DTPA.

Animals↗

PubMed1992

Estimation of relative fecundity in Eimeria tenella strains by a mixed infection method.

The relative fecundity of populations of Eimeria tenella was estimated by means of mixed infection using electrophoretic variation of glucose-phosphate isomerases (GPIs) as a genetic marker. A decoquinate-resistant strain with GPI-9 isozyme (DR-NIAH), a decoquinate-sensitive one with GPI-1 (DS-Iwate), and three decoquinate-resistant lines (No. 3, 4, and 5) derived from cross-fertilization between DR-NIAH and DS-Iwate, were used. The GPI phenotypes of the No. 3 and No. 4 lines are GPI-9, and that of No. 5 is GPI-1. Mixed infection experiments were performed between DR-NIAH and DS-Iwate, No. 3 and No. 5, and No. 4 and No. 5. DR-NIAH was predominant over DS-Iwate in the mixed infection, whereas, in single infections, the total oocyst output of DR-NIAH was similar to or less than that of DS-Iwate. Among three lines, No. 4 was predominant over No. 5, and No. 5 was predominant over No. 3 in the mixed infection. Relative fecundity between No. 3 and No. 5 and their patterns of oocyst output in single infections were similar to those in the mixed infection. In contrast, No. 5 produced more oocysts than No. 4 in single infections, suggesting that the oocyst production in the mixed infection may be influenced by the mutual interference or competition between the populations of E. tenella in the chicken caeca.

Animals↗

PubMed1977

Side reactions in peptide synthesis. V.A reexamination of the mixed anhydride method.

Acylation of amino acid beta-naphthylamides with protected (Boc) amino acidisobutylcarbonic acid mixed anhydrides resulted in each case in the formation of some undesired by-product: an isobutyloxycarbonylamino acid beta-naphthylamide. The amount of this second acylation product was particularly high, with the hindered amino acids valine and isoleucine as carboxyl-components. The nature of the amino component had no major influence on the extent of this side reaction.

Acylation↗

PubMed1986

Hapten-protein conjugates prepared by the mixed anhydride method. Cross-reactive antibodies in heterologous antisera.

Poly-L-lysine conjugates of three structurally unrelated mycotoxins were made by either a mixed anhydride intermediate (MA) or an activated N-hydroxysuccinimide ester intermediate (AE). Control conjugates, with no mycotoxin, were also prepared by each method. Antisera elicited by mycotoxin-albumin conjugates produced by the MA method bound to the three poly-L-lysine-MA mycotoxin conjugates and the MA control conjugate , but bound only to the poly-L-lysine-AE conjugates of the homologous mycotoxin. Binding of antisera to homologous poly-L-lysine conjugates was always inhibited by free hapten when the conjugate was prepared by the AE method but not by the MA method. The specific inhibition of antibody binding by various synthetic haptens indicated that the cross-reactions associated with the MA method were due to the undesired conjugation of isobutylformate during the mixed anhydride procedure.

Aflatoxins↗

PubMed2004

Moyer's method of mixed dentition analysis: a meta-analysis.

BACKGROUND: Mixed dentition analysis forms an essential part of an orthodontic assessment. Moyer's method which is commonly used for this analysis is based on data derived from a Caucasian population. The applicability of tables derived from the data Moyer used to other ethnic groups has been doubted. However no meta-analyses have been done to statistically prove this. OBJECTIVE: To assess the applicability of Moyer's method in different ethnic groups. STUDY DESIGN: A meta-analysis of studies done on other populations using Moyer's method. METHOD: The seven articles included in this study were identified by a literature search of Medline (1966-June 2003) using predetermined key words, inclusion and exclusion criteria. 195 articles were reviewed and meta-analyzed. RESULTS: Overall the correlation coefficients were found to be borderline in variation with a p-value of 0.05. Separation of the articles into Caucasian and Asian groups also gave borderline p-values of 0.05. CONCLUSION: Variation in the correlation coefficients of different populations using Moyer's method may fall either side. This implies that Moyer's method of prediction may have population variations. For one to be sure of the accuracy while using Moyer's method it may be safer to develop prediction tables for specific populations. Thus Moyer's method cannot universally be applied without question.

Asian People↗

PubMed2006

Surfactant gradient methods using mixed systems of cethyltrimethylammonium chloride and nonionic surfactants possessing polyoxyethylene chains for electrokinetic separation of benzoate anions as model analytes.

Surfactant gradient methods for electrokinetic separation of 10 benzoates as model organic anions were investigated using mixed micellar solutions of cetyltrimethylammonium chloride (CTAC) and nonionic surfactants possessing polyoxyethylene chains, polyoxyethylene sorbitan monolaurate (Tween 20) or polyoxyethylene lauryl ether (Brij 35). Electroosmotic flow (EOF) was eliminated virtually by a coating of the inner wall of the capillaries, and then the benzoates were detected fundamentally in the order of their hydrophobicity. In a pure CTAC system, the synergistic influences of attractive electrostatic and hydrophobic interactions gave rise to quite large retention factors of many of the benzoate anions, resulting in their coelution. Addition of an adequate amount of Tween 20 to the pure CTAC system decreased the electrostatic interaction significantly to give remarkably improved separation of the analytes, but long analysis time was required. A surfactant gradient method would be useful to decrease analysis time and to improve separation simultaneously. Under slight EOF, the micelles in the inlet reservoir can pass through and, thus, interact with all of the analytes before they were detected. In the present system, surfactant gradient separations could be performed simply by changing compositions of the surfactant solutions in the inlet reservoir during a single run. Additionally, we carried out continuous gradient separation using a simple device. Brij 35 gave an effect parallel to that by Tween 20 in migration behavior of the analytes. A practically negligible change in the level of the baseline was observed in a stepwise gradient elution with the CTAC/Brij 35 system because of the small absorbance at the detection wavelength, while that with the CTAC/Tween 20 was considerable. All the benzoates were separated completely within reasonable analysis times using both stepwise and continuous gradient programs for the concentrations of Tween 20 or Brij 35 in the presence of 100 mM CTAC.

Benzoates↗

PubMed2006

High surface area materials prepared from sewage sludge-based precursors.

This paper focuses on physical activation (CO2) and chemical activation (H3PO4, NaOH and KOH) of sewage sludge-based precursors. Our results show that (i) a simple acid washing treatment leads to a significant increase in the adsorption capacity of some precursors; (ii) under the experimental conditions tested, CO2 physical activation and chemical activation with H3PO4 were ineffective for an efficient porosity development and (iii) choosing an appropriate protocol, it is possible to obtain highly porous materials (700-1700 m2 g(-1)) by chemical activation of sludge-based precursors with alkaline hydroxides. The efficiency of the chemical activation with NaOH or KOH is very much influenced by the method used for mixing the activating agent and the precursor. The BET values of the materials obtained when physically mixing ground hydroxides with the precursor almost doubled the values obtained if other mixing methods are employed. Increasing the hydroxide:precursor ratio leads to an enhancement of the adsorption capacity of the adsorbents, with BET values ranging from 689 to 1224 m2 g(-1) for NaOH activation and from 853 to 1686 m2 g(-1) for KOH activation.

Adsorption↗

PubMed2005

Injectable biodegradable temperature-responsive PLGA-PEG-PLGA copolymers: synthesis and effect of copolymer composition on the drug release from the copolymer-based hydrogels.

Injectable biodegradable temperature-responsive poly(DL-lactide-co-glycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) triblock copolymers with DL-lactide/glycolide molar ratio ranging from 6/1 to 15/l were synthesized from monomers of DL-lactide, glycolide and polyethylene glycol and characterized by 1H NMR. The resulting copolymers are soluble in water to form free flowing fluid at room temperature but become hydrogels at body temperature. The hydrophobicity of the copolymer increased with the increasing of DL-lactide/glycolide molar ratio. In vitro dissolution studies with two different hydrophobic drugs (5-fluorouracil and indomethacin) were performed to study the effect of DL-lactide/glycolide molar ratio on drug release and to elucidate drug release mechanism. The release mechanism for hydrophilic 5-fluorouracil was diffusion-controlled, while hydrophobic indomethacin showed an biphasic profile comprising of an initial diffusion-controlled stage followed by the hydrogel erosion-dominated stage. The effect of DL-lactide/glycolide molar ratio on drug release seemed to be dependent on the drug release mechanism. It has less effect on the drug release during the diffusion-controlled stage, but significantly affected drug release during the hydrogel erosion-controlled stage. Compared with ReGel system, the synthesized copolymers showed a higher gelation temperature and longer period of drug release. The copolymers can solubilize the hydrophobic indomethacin and the solubility (13.7 mg/ml) was increased 3425-fold compared to that in water (4 microg/ml, 25 degrees C). Two methods of physical mixing method and solvent evaporation method were used for drug solubilization and the latter method showed higher solubilization efficiency.

Absorbable Implants↗

PubMed2026

Exploring Primary Care Clinicians' Sexual and Reproductive Health Care Delivery to Male Adolescents and Young Adults.

INTRODUCTION: Despite existing guidance for adolescent sexual and reproductive health (SRH) care, male adolescent SRH care receipt is inadequate. Limited research has explored factors affecting clinicians' provision of SRH care to male adolescents, specifically. METHODS: This mixed-method study with 12 primary care clinicians included a brief survey assessing care delivery practices and confidence, followed by an in-depth interview to explore factors affecting SRH care delivery. RESULTS: Clinicians reported high confidence delivering male adolescent SRH care (mean ± SD: 8.31 ± 1.71 out of 10), but delivered only about half the recommended services (20 items out of 38). Factors influencing care delivery included gaps in education/training, assumptions about male SRH care, and behavioral constraints at various levels. DISCUSSION: Findings underscore the need to strengthen male adolescent SRH care by enhancing provider training, increasing clinic-level supports, and addressing structural barriers. CONCLUSIONS: Findings can inform strategies to improve the quality and comprehensiveness of SRH services for male adolescents in primary care settings.

Humans↗

PubMed2005

Measuring patient-centered communication in patient-physician consultations: theoretical and practical issues.

The goal of patient-centered communication (PCC) is to help practitioners provide care that is concordant with the patient's values, needs and preferences, and that allows patients to provide input and participate actively in decisions regarding their health and health care. PCC is widely endorsed as a central component of high-quality health care, but it is unclear what it is and how to measure it. PCC includes four communication domains: the patient's perspective, the psychosocial context, shared understanding, and sharing power and responsibility. Problems in measuring PCC include lack of theoretical and conceptual clarity, unexamined assumptions, lack of adequate control for patient characteristics and social contexts, modest correlations between survey and observational measures, and overlap of PCC with other constructs. We outline problems in operationalizing PCC, choosing tools for assessing PCC, choosing data sources, identifying mediators of PCC, and clarifying outcomes of PCC. We propose nine areas for improvement: (1) developing theory-based operational definitions of PCC; (2) clarifying what is being measured; (3) accounting for the communication behaviors of each individual in the encounter as well as interactions among them; (4) accounting for context; (5) validating of instruments; (6) interpreting patient ratings of their physicians; (7) doing longitudinal studies; (8) examining pathways and mediators of links between PCC and outcomes; and (9) dealing with the complexity of the construct of PCC. We discuss the use of observational and survey measures, multi-method and mixed-method research, and standardized patients. The increasing influence of the PCC literature to guide medical education, licensure of clinicians, and assessments of quality provides a strong rationale for further clarification of these measurement issues.

Communication↗

PubMed2006

General health promotion in general dental practice--the involvement of the dental team Part 2: A qualitative and quantitative investigation of the views of practice principals in South Yorkshire.

AIM: To investigate the factors that might influence the provision of general health promotion through seven different health interventions by dental teams in general dental practice. METHOD: A mixed-method was used comprising cross-sectional qualitative research using semi-structured interviews of a purposive sample of 10 practice principals, and a cross sectional survey of a practice principal from every dental practice in South Yorkshire, using a self-complete questionnaire. RESULTS: Two core categories emerged from the qualitative data: seeing health or disease and practitioners' views of the structure of dental practice. The former refers to the participants' general outlook and cut across many dimensions constituting the structure of dental practice. Health-orientated dentists were more likely to be involved in prevention and were more open-minded to expanding the dental team's role into general health promotion. However participants perceived that barriers existed to involvement such as time and financial factors, current workload and lack of personal skills. The response rate of useable questionnaires in the cross sectional survey was 84%. Reported levels of involvement in general health promotion were low. Most frequently reported barriers were 'insufficient funding' and 'poor use of time'. 'Poor use of time' and 'lack of training/knowledge' were reported less frequently for professionals complementary to dentistry (PCDs) than dentists (p<0.05). Most dentists agreed that PCDs could be trained to deliver health interventions and would be happy for PCDs to do so in their practice if reported barriers were removed. CONCLUSIONS: Although dental teams' involvement in general health promotion is low, there is willingness to increase involvement, particularly among health-orientated dentists. Some reported barriers to involvement might be removed by impending changes to the GDS in England. Other important factors include a lack of education and workforce shortages of dentists and PCDs. Respondents indicated a high regard for PCDs and there was broad agreement that they were suitable to be involved in this work.

Attitude of Health Personnel↗

PubMed2003

DARTS 2000 online diabetes management system: formative evaluation in clinical practice.

RATIONALE, AIMS AND OBJECTIVES: Failure to engage in user-informed evaluation of emergent health informatics tools can have negative consequences for future implementation, related both to poor usability or clinical utility and to suboptimal stakeholder buy-in. This paper describes a formative evaluation in primary care of a multifaceted, web-based resource for diabetes management. The primary aims were to assess the usability and utility of the prototype in order to inform system refinements prior to implementation, and to investigate barriers and facilitators to system use so as to aid the development of a tailored implementation plan. METHODS: A mixed-method approach involving survey, remote observation, semi-structured interviews and electronic feedback. CONTEXT: One Scottish local health care cooperative comprising five general practice surgeries and their staff. RESULTS: A survey following temporary exposure to a dummy site revealed high levels of computer familiarity, welcoming attitudes and positive ratings of usability, format and utility. Comments mainly addressed content accuracy, feature suggestions and usability issues. Key barriers and facilitators to use included time and training. Remote observation following access to live clinical data enabled profiling of usage by individual and professional group. In the 3 month observation period administrators were the most frequent users, followed by GPs and nurses, with clinical and data entry screens accessed most often. Semi-structured interviews with key respondents sampled by professional group and usage frequency provided richer qualitative information on barriers and facilitators to use, patterns of system integration into work routines and system usability, content and utility. Content analysis of electronic feedback revealed mainly technical queries and general expressions of satisfaction. CONCLUSIONS: Evaluation informed a number of important and unforeseen improvements to the prototype and helped refine the implementation plan. Engagement in the process of evaluation has led to high levels of stakeholder ownership and widespread implementation.

Attitude to Computers↗

PubMed2002

Learning preferences, computer attitudes, and student evaluation of computerised instruction.

OBJECTIVE: To explore the relationship between learning preferences, attitudes towards computers, and student evaluation of a computer-assisted instructional (CAI) program. CONTEXT: A third year required clerkship in surgery at the University of Nebraska Medical Center. METHODS: A mixed-methods design combining attitudinal measures and qualitative interviews was employed to assess student reactions to a CAI program on angiography completed during a required surgical clerkship. Between January 1998 and July 1999, 151 students completed the program. Prior to participating, students completed the Rezler Learning Preference Inventory (LPI) and a computer attitudes survey (CAS). The LPI characterizes learning preferences as being abstract or concrete, individual or interpersonal, and student-structured or teacher-structured. The CAS measures attitudes towards computers and their role in education. After using the CAI program, students evaluated the module by completing an 18 item questionnaire. Based on LPI and CAS scores, 31 students were invited to participate in an in-depth qualitative interview on their experiences and perceptions of the program. RESULTS: There was no relationship between learning preferences, computer attitudes, and evaluation of the CAI program. Students were very positive about the program's content, clarity, organization, and ease of use. They also rated it as efficient and effective. However, many still indicated a preference for lecture and text-based learning. Qualitative interviews suggest students worry computers will supplant student--teacher contact. CONCLUSIONS: Learning preferences and prior attitudes toward computers did not bias student reactions to the CAI program assessed in this study. However, students expressed concerns that CAI would interfere with the traditional student--teacher encounter and relationship.

Attitude to Computers↗