bluuebunny/crossref_metadata_2025 huggingface dataset:
The linkage between childhood bullying behaviour and future offending
Authors: Jiang Depeng , Walsh Margaret , Augimeri Leena K.
Published: March 2011

Aim To examine the linkage between bullying behaviour in early childhood and any subsequent contact with the criminal justice system.

Methods A Canadian sample (570 boys and 379 girls) was derived from clients who participated in the evidenced‐based programme, SNAP® (STOP NOW AND PLAN), between 2001 and 2009. A court order was obtained to access any criminal record data on participants. The Early Assessment Risk Lists (EARL‐20B and EARL‐21G) and the Child Behavior Checklist (CBCL) were used to identify level of risk and bullying behaviour. Outcome variables included age the child first came in contact with the criminal justice system and frequency.

Results Logistic and Cox regression analyses indicate that the risk of onset of criminal offence for bullies was significantly higher than for non‐bullies. The hazard of criminal offence for bullies is 1.9 times (95% CI: 1.1–3.2) than that of non‐bullies. This holds true even when adjusted for age, gender and other risk factors.

Conclusion We found a strong linkage between bullying behaviour during childhood and subsequent criminal offending after the age of 12. Criminal convictions for bullies were nearly twice as high for non‐bullies up to the child's 18th birthday. EARLs were effective in differentiating risk associated with bullying. Copyright © 2011 John Wiley & Sons, Ltd.
Bullying at elementary school and problem behaviour in young adulthood: A study of bullying, violence and substance use from age 11 to age 21
Authors: Kim Min Jung , Catalano Richard F. , Haggerty Kevin P. , Abbott Robert D.
Published: March 2011

Aim The main aim of this paper is to investigate to what extent self‐reported bullying at Grade 5 predicts later violence, heavy drinking and marijuana use at age 21.

Method Univariate and multivariate associations between bullying and later outcomes were examined based on a longitudinal community sample of 957 young people from the Raising Healthy Children project.

Results Childhood bullying was significantly associated with violence, heavy drinking and marijuana use at age 21. These associations held up after controlling for prior risk factors.

Conclusions Childhood bullying had unique associations with risk of later violence and substance use among young adults. Early intervention to prevent childhood bullying may also reduce other adverse outcomes later in life. Copyright © 2011 John Wiley & Sons, Ltd.
Bullying at school and later criminality: Findings from three Swedish community samples of males
Authors: Olweus Dan
Published: March 2011

Aim To examine whether being a bully at school predicts later criminality.

Method Longitudinal, prospective associations are reported between bullying and later criminality over the 8‐year period from age 16 to 24.

Results Bullying in early adolescence strongly predicted later criminality. The former school bullies were heavily overrepresented in the crime registers. Some 55% of them had been convicted of one or more crimes and as much as 36% had been convicted of at least three crimes in the studied period. Effect sizes in the form of Odds Ratios were substantial for both general crimes and violent crimes, varying between 3.47 and 7.79. Copyright © 2011 John Wiley & Sons, Ltd.
The predictive efficiency of school bullying versus later offending: A systematic/meta‐analytic review of longitudinal studies
Authors: TTOFI Maria M. , Farrington David P. , Lösel Friedrich , Loeber Rolf
Published: March 2011

Background Although bullying and delinquency share similar risk factors, no previous systematic review has ever been conducted to examine possible links between school bullying and criminal offending later in life.

Aims To investigate the extent to which bullying perpetration at school predicts offending later in life, and whether this relation holds after controlling for other major childhood risk factors.

Method Results are based on a thorough systematic review and meta‐analysis of studies measuring school bullying and later offending. Effect sizes are based on both published and unpublished studies; longitudinal investigators of 28 studies have conducted specific analyses for our review.

Results The probability of offending up to 11 years later was much higher for school bullies than for non‐involved students [odds ratio (OR) = 2.50; 95% confidence interval (CI): 2.03–3.08]. Bullying perpetration was a significant risk factor for later offending, even after controlling for major childhood risk factors (OR = 1.82, 95% CI: 1.55–2.14). Effect sizes were smaller when the follow‐up period was longer and larger when bullying was assessed in older children. The age of participants when outcome measures were taken was negatively related with effect sizes. Finally, the summary effect size did not decrease much as the number of controlled risk factors increased.

Conclusions School bullying is a strong and specific risk factor for later offending. Effective anti‐bullying programmes should be promoted, and could be viewed as a form of early crime prevention. Such programmes would have a high benefit : cost ratio. Copyright © 2011 John Wiley & Sons, Ltd.
SAG mill system diagnosis using multivariate process variable analysis
Authors: Ko Young‐Don , Shang Helen
Published: March 2011

Semi‐autogenous grinding (SAG) of ore plays a critical role in a mineral processing plant. In SAG operations, abnormal conditions, such as overload or insufficient ore holdup, often result in inefficient production and unstable operation. It is, therefore, essential to monitor the process using effective technology so that abnormal or faulty conditions can be detected and addressed in a timely manner. In this study, investigation is focused on applying multivariate analysis in the monitoring and diagnosing of an industrial SAG operation. The results show that principal component analysis provides an effective methodology for on‐line monitoring and diagnosis. The detection and removal of faulty conditions will help to provide stable and cost‐efficient operation.
Catalytic spectrophotometric determination of iodide in pharmaceutical preparations and edible salt
Authors: El‐Ries M.A. , Khaled Elmorsy , Zidane F.I. , Ibrahim S.A. , Abd‐Elmonem M.S.
Published: March 2011

The catalytic effect of iodide on the oxidation of four dyes: viz. variamine blue (VB), methylene blue (MB), rhodamine B (RB), and malachite green (MG) with different oxidizing agents was investigated for the kinetic spectrophotometric determination of iodide. The above catalyzed reactions were monitored spectrophotometrically by following the change in dye absorbances at 544, 558, 660, or 617 nm for the VB, RB, MB, or MG catalyzed reactions, respectively. Under optimum conditions, iodide can be determined within the concentration levels 0.064–1.27 µg mL−1 for VB method, 3.20–9.54 µg mL−1 for RB method, 5.00–19.00 µg mL−1 for the MB method, and 6.4–19.0 µg mL−1 for the MG one, with detection limit reaching 0.004 µg mL−1 iodide. The reported methods were highly sensitive, selective, and free from most interference. Applying the proposed procedures, trace amounts of iodide in pharmaceutical and edible salt samples were successfully determined without separation or pretreatment steps. Copyright © 2011 John Wiley & Sons, Ltd.
Applying cloud point extraction technique for the extraction of oxazepam from human urine as a colour or fluorescent derivative prior to spectroscopic analysis methods
Authors: Tabrizi Ahad Bavili , Harasi Maryam
Published: March 2011

Two new methods based on cloud point extraction (CPE) technique were developed and optimized for the extraction and preconcentration of oxazepam from human urine, as an azo or fluorescent derivative. The first method is a spectrophotometric one, which is based on the acid hydrolysis of the oxazepam to a benzophenone, diazotization of the benzophenone, and then the coupling with oxine to form an azo dye. The second method is a spectrofluorimetric one, which involves reduction of the target compound using Zn°/HCl at room temperature with the formation of a highly fluorescent derivative. The main factors affecting the chemical reactions and CPE were investigated and optimized systematically. Under optimum experimental conditions, the calibration graphs were linear in the range of 0.1 to 1.5 (0.05 to 2.0) µg/ml with correlation coefficients of 0.9989 (0.9985), for the CPE‐spectrophotometric (CPE‐spectrofluorimetric) method. The limit of detection was found to be 0.034 (0.018) µg/ml and the relative standard deviation was calculated to be 1.35 (2.52)%. Recoveries in the spiked samples ranged from 87 to 94%. Finally, the proposed methods were applied to the determination of oxazepam in human urine. Copyright © 2011 John Wiley & Sons, Ltd.
In vitro metabolic studies using homogenized horse liver in place of horse liver microsomes
Authors: Wong Jenny K. Y. , Tang Francis P. W. , Wan Terence S. M.
Published: March 2011

The study of the metabolism of drugs, in particular steroids, by both in vitro and in vivo methods has been carried out in the authors' laboratory for many years. For in vitro metabolic studies, the microsomal fraction isolated from horse liver is often used. However, the process of isolating liver microsomes is cumbersome and tedious. In addition, centrifugation at high speeds (over 100 000 g) may lead to loss of enzymes involved in phase I metabolism, which may account for the difference often observed between in vivo and in vitro results. We have therefore investigated the feasibility of using homogenized horse liver instead of liver microsomes with the aim of saving preparation time and improving the correlation between in vitro and in vivo results. Indeed, the preparation of the homogenized horse liver was very simple, needing only to homogenize the required amount of liver. Even though no further purification steps were performed before the homogenized liver was used, the cleanliness of the extracts obtained, based on gas chromatography‐mass spectrometry (GC‐MS) analysis, was similar to that for liver microsomes. Herein, the results of the in vitro experiments carried out using homogenized horse liver for five anabolic steroids—turinabol, methenolone acetate, androst‐4‐ene‐3,6,17‐trione, testosterone, and epitestosterone—are discussed. In addition to the previously reported in vitro metabolites, some additional known in vivo metabolites in the equine could also be detected. As far as we know, this is the first report of the successful use of homogenized liver in the horse for carrying out in vitro metabolism experiments. Copyright © 2011 John Wiley & Sons, Ltd.
Transgenic mice for cre‐inducible overexpression of the Cul4A gene
Authors: Li Tong , Hung Ming‐Szu , Wang Yucheng , Mao Jian‐Hua , Tan Jia‐Li , Jahan Kenneth , Roos Hannah , Xu Zhidong , Jablons David M. , You Liang
Published: March 2011

The Cullin 4A(Cul4A) gene is important in cell survival, development, growth, and cell cycle control and is amplified in breast and hepatocellular cancers. Recently, we reported that Cul4A plays an oncogenic role in the pathogenesis of mesothelioma. An important strategy for studying Cul4A in different tissues is targeted overexpression of this gene in vivo. Studies of Cul4A in mice have been restricted to the loss‐of‐function studies using Cul4A knockout mice; gain‐of‐function studies of Cul4A using transgenic mice have not been reported. We, therefore, generated a gain‐of‐function transgenic mouse model that overexpresses Cul4A in a Cre‐dependent manner. Before Cre recombination, these mice express LacZ during development in most adult tissues. After Cre‐mediated excision of the LacZ reporter, the transfected Cul4A gene is expressed along with a C‐terminal Myc‐tag in different tissues. In this study, Cre‐excision was induced in mouse lungs by inhalation of an adenovirus vector encoding Cre recombinase. This mouse model provides a valuable resource for investigating the significance of Cul4A overexpression in various tissues. genesis 49:134–141, 2011. © 2011 Wiley‐Liss, Inc.
Making connections: changing sediment sources and sinks in an upland catchment
Authors: Lexartza‐Artza Irantzu , Wainwright John
Published: March 2011

The effect of changes in catchment processes and conditions can be studied by using connectivity as a framework for understanding the feedbacks and interactions occurring within the system. The sediment record preserved in reservoirs can be a useful archive of catchment changes, but needs to be considered in conjunction with the different elements that compose and act on the system to take into account its complexity. Changing patterns of connectivity have been studied in the Ingbirchworth Catchment (Yorkshire, UK), using a multiple methodology approach combining the analysis of reservoir‐sediment records with knowledge of recent land‐use history, high resolution rainfall records, catchment characteristics and management aspects. Sedimentation rates inferred from reservoir‐sediment cores from two reservoirs in the Ingbirchworth catchment show sedimentation peaks which coincide with periods of significant changes in the catchment, such as the introduction of arable crops, the establishment of land drainage and the widespread intensification and mechanization of agriculture. Rainfall patterns, including combinations of events such as droughts and increased precipitation, contribute to increased sediment transfer under catchment conditions in which more sediment and/or new pathways are made available due to catchment changes. Sediment fingerprinting supports the notion that changes in sedimentation rates are not just related to increased/reduced erosion and transport in the same areas, but also to the establishment of different pathways increasing sediment connectivity. The results demonstrate that typical calculations of catchment‐area yields are not sufficient as sediment‐contributing areas vary as a consequence of changing conditions. The study provides insights into the complex interactions influencing connectivity, such as the relation between catchment changes and climatic inputs, and the subsequent effect on catchment conditions and transfer networks. Copyright © 2011 John Wiley & Sons, Ltd.
Antifungal efficacy of environmentally friendly wood preservatives formulated with enzymatic-hydrolyzed okara, copper, or boron salts
Authors: Kim Ho-Yong , Jeong Han-Seob , Min Byeong-Cheol , Ahn Sye Hee , Oh Sei Chang , Yoon Young-ho , Choi In-Gyu , Yang In
Published: March 2011

Okara, an organic waste product obtained from soy milk production, was used with copper chloride or sodium borate to formulate new wood preservatives as a substitute for expensive wood preservatives, such as copper-azole–based preservatives and ammoniacal copper quaternary. Before formulating the preservatives, okara was hydrolyzed by enzymes (cellulase, pectinase, and protease) to augment penetration and fix the biocide salts of the preservatives into wood blocks. The preservatives were injected into wood blocks by vacuum pressure to measure the treatability of the preservatives. The treated wood blocks were placed in hot water for 3 d to measure leachability. The treatability and leachability of the preservatives were affected by the type and loading amount of enzymes and the addition of sodium borate into okara-based wood preservative formulations. The treatability and leachability of the preservatives formulated with copper chloride and okara hydrolysates were 63.38 and 3.15%, and those of the preservatives with copper chloride, okara hydrolysates, and sodium borate were 61.47 and 3.32%, respectively. Despite the hot water leaching, wood blocks treated with preservatives formulated with 2% cellulase, pectinase, and protease hydrolyzed okara, CuCl2, and sodium borate showed only 1.98% average weight loss against Fomitopsis palustris over 12 weeks. Microscopic observation revealed how okara-based preservatives work in wood blocks. Okara has potential as a raw material for cost-effective and environmentally friendly wood preservatives. Environ. Toxicol. Chem. 2011; 30:1297–1305. © 2011 SETAC
Toxic effects of dietary methylmercury on immune system development in nestling American kestrels (Falco sparverius)
Authors: Fallacara Dawn M , Halbrook Richard S , French John B
Published: March 2011

This study evaluated the effects of dietary methylmercury (MeHg) on immune system development in captive-reared nestling American kestrels (Falco sparverius) to determine whether T cell–mediated and antibody-mediated adaptive immunity are targets for MeHg toxicity at environmentally relevant concentrations. Nestlings received various diets, including 0 (control), 0.6, and 3.9 µg/g (dry wt) MeHg for up to 18 d posthatch. Immunotoxicity endpoints included cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and antibody-mediated immune response via the sheep red blood cell (SRBC) hemagglutination assay. T cell– and B cell–dependent histological parameters in the spleen, thymus, and bursa of Fabricius were correlated with the functional assays. For nestlings in the 0.6 and 3.9 µg/g MeHg groups, CMI was suppressed by 73 and 62%, respectively, at 11 d of age. Results of this functional assay were correlated with T cell–dependent components of the spleen and thymus. Dose-dependent lymphoid depletion in spleen tissue directly affected the proliferation of T-lymphocyte populations, insofar as lower stimulation indexes from the PHA assay occurred in nestlings with lower proportions of splenic white pulp and higher THg concentrations. Nestlings in the 3.9 µg/g group also exhibited lymphoid depletion and a lack of macrophage activity in the thymus. Methylmercury did not have a noticeable effect on antibody-mediated immune function or B cell–dependent histological correlates. We conclude that T cell–mediated immunosuppression is the primary target of MeHg toward adaptive immunity in developing kestrels. This study provides evidence that environmentally relevant concentrations of MeHg may compromise immunocompetence in a developing terrestrial predator and raises concern regarding the long-term health effects of kestrels that were exposed to dietary MeHg during early avian development. Environ. Toxicol. Chem. 2011; 30:1328–1337. © 2011 SETAC
Loss of adenomatous polyposis coli in Bergmann glia disrupts their unique architecture and leads to cell nonautonomous neurodegeneration of cerebellar Purkinje neurons
Authors: Wang Xiaohong , Imura Tetsuya , Sofroniew Michael V. , Fushiki Shinji
Published: March 2011

The tumor suppressor adenomatous polyposis coli (APC) is a multifunctional protein that inhibits the Wnt/beta‐catenin signaling pathway and regulates the microtubule and actin cytoskeletons. Using conditional knockout (CKO) mice in which the APC gene is inactivated in glial fibrillary acidic protein (GFAP)‐expressing cells, we show a selective and critical role for APC in maintaining the morphology and function of cerebellar Bergmann glia, which are specialized astroglia that extend polarized radial processes from the Purkinje cell layer to the pial surface. APC‐CKO mice developed Bergmann glia normally until the accumulation of beta‐catenin started around postnatal day 10 (P10). Their radial fibers then became shortened with a marked reduction of branching collaterals and their cell bodies translocated into the molecular layer followed by loss of their pial contact and transformation into stellate‐shaped cells by P21. Purkinje neurons were normal in appearance and number at P21, but there was significant loss of Purkinje neurons and cerebellar atrophy by middle age. Outside the cerebellum, neither beta‐catenin accumulation nor morphological changes were identified in GFAP‐expressing astroglia, indicating region‐specific effects of APC deletion and an essential role for APC in maintaining the unique morphology of Bergmann glia as compared with other astroglia. These results demonstrate that loss of APC selectively disrupts the Bergmann glial scaffold in late postnatal development and leads to cerebellar degeneration with loss of Purkinje neurons in adults, providing another potential mechanism for region‐specific non‐cell autonomous neurodegeneration. © 2011 Wiley‐Liss, Inc.
Transoral laser surgery versus radiotherapy: Systematic review and meta‐analysis for treatment options of T1a glottic cancer
Authors: Abdurehim Yasin , Hua Zhang , Yasin Yalkun , Xukurhan Ayihen , Imam Ilham , Yuqin Fan
Published: March 2011

Background

The objective of this study was to conduct a systematic review and meta‐analysis to compare the oncologic and functional outcomes between transoral laser surgery (TLS) and radiotherapy (RT).

Methods

An electronic library search of the relevant English‐ and Chinese‐language literature was conducted. Potentially eligible articles were reviewed. Qualified articles were selected and evaluated.

Results

No significant differences were identified between TLS and RT with respect to local control, overall survival, disease‐specific survival, and posttreatment voice quality. However, larynx preservation was significantly higher in patients initially treated with TLS than those initially treated with RT.

Conclusions

The approach for optimal treatment of T1a glottic cancer remains unanswered. This results from the relatively inconclusive evidence obtained from the current literature. Properly designed, prospective, randomized, or well‐controlled studies will be required. Similar methodologies for treatment and reporting need to be established to make a valid and meaningful comparison between studies. © 2011 Wiley Periodicals, Inc. Head Neck, 2012
Consideration of dosimetry in evaluation of ToxCast™ data
Authors: Aylward Lesa L. , Hays Sean M.
Published: March 2011

The US Environmental Protection Agency (US EPA) Toxcast™ program has the stated goal of predicting hazard, characterizing toxicity pathways and prioritizing the toxicity testing of environmental chemicals through the use of in vitro high‐throughput screening (HTS) assays. This analysis integrates data from biomonitoring and from in vivo toxicity and pharmacokinetic studies to examine the physiological relevance of the tested and responding in vitro concentrations for five case study chemicals: triclosan, 2,4‐dichlorophenoxyacetic acid, perfluorooctanoic acid, monobutyl phthalate and mono‐2(ethylhexyl)phthalate. This analysis also examines the ToxCast™ phase 1 data set for approximately 50 chemicals belonging to four ‘common mechanism groups’ which have been the subject of cumulative risk assessments by the US EPA for both the pattern of key responses and the relative potencies of included chemicals compared with the in vivo relative potencies. Responding concentrations in vitro were generally in the range of serum or plasma concentrations associated with no‐observed to lowest‐observed effect levels for the case study chemicals, while available biomonitoring data demonstrating actual exposures were generally lower. ToxCast™ assay endpoints related to acetylcholinesterase (AChE) inhibition had low sensitivity for detecting organophosphate pesticides but good sensitivity for detecting N‐methyl carbamates. However, in vitro relative potencies did not correlate with in vivo potency. Both qualitative and quantitative predictive power is probably affected by the lack of comprehensive metabolic activity in most current in vitro systems explored in the ToxCast™ program, and this remains a fundamental challenge for high‐throughput toxicity screening efforts. Copyright © 2011 John Wiley & Sons, Ltd.
Reduction in fluoride‐induced genotoxicity in mouse bone marrow cells after substituting high fluoride‐containing water with safe drinking water
Authors: Podder Santosh , Chattopadhyay Ansuman , Bhattacharya Shelley
Published: March 2011

Treatment of mice with 15 mg l−1 sodium fluoride (NaF) for 30 days increased the number of cell death, chromosomal aberrations (CAs) and ‘cells with chromatid breaks’ (aberrant cells) compared with control. The present study was intended to determine whether the fluoride (F)‐induced genotoxicity could be reduced by substituting high F‐containing water after 30 days with safe drinking water, containing 0.1 mg F ions l−1. A significant fall in percentage of CAs and aberrant cells after withdrawal of F‐treatment following 30 days of safe water treatment in mice was observed which was highest after 90 days, although their levels still remained significantly high compared with the control group. This observation suggests that F‐induced genotoxicity could be reduced by substituting high F‐containing water with safe drinking water. Further study is warranted with different doses and extended treatment of safe water to determine whether the induced damages could be completely reduced or not. Copyright © 2011 John Wiley & Sons, Ltd.
Toxicokinetics of captan and folpet biomarkers in orally exposed volunteers
Authors: Berthet Aurélie , Bouchard Michèle , Danuser Brigitta
Published: March 2011

The time courses of key biomarkers of exposure to captan and folpet was assessed in accessible biological matrices of orally exposed volunteers. Ten volunteers ingested 1 mg kg−1 body weight of captan or folpet. Blood samples were withdrawn at fixed time periods over the 72 h following ingestion and complete urine voids were collected over 96 h post‐dosing. The tetrahydrophthalimide (THPI) metabolite of captan along with the phthalimide (PI) and phthalic acid metabolites of folpet were then quantified in these samples. Plasma levels of THPI and PI increased progressively after ingestion, reaching peak values ~10 and 6 h post‐dosing, respectively; subsequent elimination phase appeared monophasic with a mean elimination half‐life (t½) of 15.7 and 31.5 h, respectively. In urine, elimination rate time courses of PI and phthalic acid evolved in parallel, with respective t½ of 27.3 and 27.6 h; relatively faster elimination was found for THPI, with mean t½ of 11.7 h. However, phthalic acid was present in urine in 1000‐fold higher amounts than PI. In the 96 h period post‐treatment, on average 25% of folpet dose was excreted in urine as phthalic acid as compared with only 0.02% as PI. The corresponding value for THPI was 3.5%. Overall, THPI and PI appear as interesting biomarkers of recent exposure, with relatively short half‐lives; their sensitivity to assess exposure in field studies should be further verified. Although not a metabolite specific to folpet, the concomitant use of phthalic acid as a major biomarker of exposure to folpet should also be considered. Copyright © 2011 John Wiley & Sons, Ltd.
Toxicokinetics of captan and folpet biomarkers in dermally exposed volunteers
Authors: Berthet Aurélie , Bouchard Michèle , Vernez David
Published: March 2011

To better assess biomonitoring data in workers exposed to captan and folpet, the kinetics of ring metabolites [tetrahydrophthalimide (THPI), phthalimide (PI) and phthalic acid] were determined in urine and plasma of dermally exposed volunteers. A 10 mg kg−1 dose of each fungicide was applied on 80 cm2 of the forearm and left without occlusion or washing for 24 h. Blood samples were withdrawn at fixed time periods over the 72 h following application and complete urine voids were collected over 96 h post‐dosing, for metabolite analysis. In the hours following treatment, a progressive increase in plasma levels of THPI and PI was observed, with peak levels being reached at 24 h for THPI and 10 h for PI. The ensuing elimination phase appeared monophasic with a mean elimination half‐life (t½) of 24.7 and 29.7 h for THPI and PI, respectively. In urine, time courses PI and phthalic acid excretion rate rapidly evolved in parallel, and a mean elimination t½ of 28.8 and 29.6 h, respectively, was calculated from these curves. THPI was eliminated slightly faster, with a mean t½ of 18.7 h. Over the 96 h period post‐application, metabolites were almost completely excreted, and on average 0.02% of captan dose was recovered in urine as THPI while 1.8% of the folpet dose was excreted as phthalic acid and 0.002% as PI, suggesting a low dermal absorption fraction for both fungicides. This study showed the potential use of THPI, PI and phthalic acid as key biomarkers of exposure to captan and folpet. Copyright © 2011 John Wiley & Sons, Ltd.
Selective separation of n‐butanol from aqueous solutions by pervaporation using silicone rubber‐coated silicalite membranes
Authors: Ikegami Toru , Negishi Hideyuki , Sakaki Keiji
Published: March 2011

BACKGROUND: To use butanol as a liquid fuel and feedstock, it is necessary to establish processes for refining low‐concentration butanol solutions. Pervaporation (PV) employing hydrophobic silicalite membranes for selective recovery of butanol is a promising approach. In this study, the adsorption behavior of components present in clostridia fermentation broths on membrane material (silicalite powder) was investigated. The potential of PV using silicone rubber‐coated silicalite membranes for the selective separation of butanol from model acetone–butanol–ethanol (ABE) solutions was investigated.

RESULTS: The equilibrium adsorbed amounts of ABE per gram of silicalite from aqueous solutions of binary mixtures at 30 °C increased as follows: ethanol (95 mg) < acetone (100 mg) < n‐butanol (120 mg). The amount of butanol adsorbed is decreased by the adsorption of acetone and butyric acid. In the separation of ternary butanol/water/acetone mixtures, the enrichment factor for acetone decreased, compared with that in binary acetone/water mixtures. In the separation of a model acetone–butanol–ethanol (ABE) fermentation broth containing butyric acid by PV using a silicone rubber‐coated silicalite membrane, the permeate butanol concentration was comparable with that obtained in the separation of a model ABE broth without butyric acid. The total flux decreased with decreasing feed solution pH.

CONCLUSION: A silicone rubber‐coated silicalite membrane exhibited highly selective PV performance in the separation of a model ABE solution. It is very important to demonstrate the effectiveness of PV in the separation of actual clostridia fermentation broths, and to identify the factors affecting PV performance. Copyright © 2011 Society of Chemical Industry
Rainfall variability in Congo‐Brazzaville: 1932–2007
Authors: Samba Gaston , Nganga Dominique
Published: March 2011

The interannual variability of rainfall amounts and rainy days is analysed from synoptic stations located in different climatic zones of Congo‐Brazzaville over the common period 1932–2007. The annual and seasonal rainfall evolution is appreciated using standardized indices. Trends examined were based on the non‐parametric Mann‐Kendall test (the major synoptic stations point out alternative periods of anomalies—positive and negative). A majority of negative anomalies is recorded during the 1930s and 1940s. The decade 1950 shows mainly positive anomalies with the exception of 1958 which records a general precipitation deficit all across Congo. The decade 1960 is characterized by precipitation excess over the whole Congo. The decades 1980 and 1990 experience the largest rainfall deficit (about 10–20% below the long‐term mean). The evolution of the precipitation at Brazzaville is particularly stable, although there are large positive anomalies during the 1990s. The transition between positive and negative anomalies decades is not uniform across Congo. The progressive non‐parametric Mann‐Kendall trend test shows that there is stability in the annual rainfall and rainy days over the southern area in the period 1932–2007. By contrast, the annual rainfall for the northern stations shows a significant decline since about the 1980s. In the south the decline is observable only in the evolution of the March–May seasonal rainfall. In most of the stations there is a precipitation increase during the September‐November rainy season. Copyright © 2011 Royal Meteorological Society
Dynamical problems in the theory of polymer solutions
Authors: Fixman Marshall
Published: March 2011

Qualitative discrepancies are found between what is predicted by available theory and what is actually observed, for several concentration regimes of the dynamical properties of polymer solutions. The difficulties are most severe, from the standpoint of experiment or simulation as well as theory, for the entanglement concentration regime. However, the classical problems of chain polymers in dilute solution are not fully understood. For example, the constants of proportionality that relate hydrodynamic radii to the radius of gyration, in the nondraining limit and in theta solvents, may not be universal constants. That is, the proportionality constants may vary with polymer and solvent species. Discrepancies between theory and experiment are discussed for the two different systems, dilute chains and semidilute rods. Speculation is offered on the resolution of these difficulties.
Environment induced changes in DNA structure
Authors: Baase Walter A. , Schellman John A.
Published: March 2011

Investigations over the past decade have disclosed that the structure of DNA in solution is far from uniform and static. The present view of DNA structure is that it is: 1) dynamically variable, displaying relatively large flexibility in both bending and torsional modes, 2) it is not perfectly helical because of sequence dependent departures from a regular helix and 3) it is capable of adopting entirely different conformations, including a switch in the sense of the helix as is the case for the B to Z transition, as well as new folding patterns as is the case for cation induced DNA collapse.

One of the principal problems in the field today is the detection and evaluation of structural changes in solution. Many experimental techniques are in use and a number of these will be reviewed. The discussion includes models of flexible DNA, the structural aspects revealed by several experimental techniques, and results for a number of systems in which solution environment brings about changes in structure.
Synthetic membrane active polyelectrolytes in design of artificial immunogens and vaccines
Authors: Kabanov Victor A.
Published: March 2011

Chemical binding or strong complexing of individual antigens (proteins, polysaccharides) or antigenic determinants with non‐natural membrane active polyelectrolytes results in formation of effective immunogens with high protective properties. These artificial antigenic conjugates develop strong immunogenicity also in the absence of T‐cells. The strength of the immune response is not controlled by Ir‐genes. An antigenic moiety of a conjugate is responsible for its “focusing” on B‐lymphocytes of the proper clone. Linear polyion moiety being adsorbed on the cell membrane surface aggregates membrane proteins and induces nonspecific transmembrane ionic permeability. K+‐flux from the cell and Ca+2‐flux into the cell disturb cell homeostasis and thus, pull trigger mechanism of K+, Na+‐ATPase and Ca+2‐ATPase activity. Then the cell synthesizing apparatus starts to operate. The covalent conjugates of Salmonella typhimurium and influenza A‐virus individual antigens with synthetic polyelectrolytes seem to represent a new generation of vaccinating macromolecules.
Liquid crystal polymers 23. Steric and polar effects of large substituents in thermotropic aromatic polyesters with decamethylene spacers
Authors: Furukawa Akira , Lenz Robert W.
Published: March 2011

A series of thermotropic aromatic polyesters based on a triad ester mesogenic unit containing an arylsulfonyl substituted hydroquinone group and a decamethylene spacer group was prepared. The large arylsulfonyl substituent was substituted in the para‐position with either electron donating or accepting groups to study the effect of steric and polar interactions on the thermal transitions of these polymers and on the thermodynamic parameters of their isotropization transitions. All polymers formed nematic melts, and a regular decrease in T1, ΔH1 and ΔS1 was observed with increasing molecular radius of the substituted hydroquinone group. However, a polarity or polarizability effect was superimposed on these relationships. Model compounds containing the same aromatic ester triad were prepared and their thermotropic properties were compared to those of the polymers. Essentially identical effects were observed for both.
Polyurethane elastomers from tdi and castor oil
Authors: Cuadrado T. R. , Williams R. J. J.
Published: March 2011

Polyurethane elastomers were prepared by reacting castor oil with toluene diisocyanate (TDI) in pure (80:20) and crude (TDI R) grades. Different elastomers were prepared by using several stoichiometric imbalances, always in defect of NCO groups. Their characterization involved the determination of the glass transition temperature (TMA), the sol fraction (extraction with toluene) and the concentration of elastically active network chains (swelling in benzene). Experimental results were compared with theoretical predictions resulting from a statistical model of the network formation.
Applicability of the configurational analysis to some problems of interest in polymer science
Authors: Riande Evaristo
Published: March 2011

Comparison between theoretical and experimental values of configuration dependent properties of polymers is used to estimate the values of the conformational energies associated with the rotational states of molecular chains. It is shown that the critical interpretation of the configurational properties of the polymers obtained by cationic polymerization of heterocycles, may be an useful tool to elucidate the ring‐opening mechanisms. The influence of the molecular flexibility in both the glass transition temperature and melting temperature of polymers is discussed in terms of the configurational entropy.
Control of particle size distribution in latices through periodic operation of continuous emulsion polymerization reactors
Authors: Gugliotta L. M. , Meira G. R.
Published: March 2011

A method is proposed which allows to obtain latices with prespecified number particle size distributions (NPSD), with the only restriction that the said distributions must be monotonically descendent. To this effect, the forced periodic operation of the total feed flow into a continuous stirred‐tank reactor (CSTR) is considered. The method is limited to emulsion polymerizations occurring within intervals 1 and 2 of Harkins' mechanism (1), and verifying kinetics of case II (2,3,4). Furthermore, because the procedure has been developed through a steady state (SS) model, the method is strictly valid in the limit of very low frequencies of oscillation. The technique is illustrated by means of a numerical example.
Addition reactions of carbocations with alkenes: Studies on the mechanism of carbocationic polymerization
Authors: Mayr Herbert , Pock Rudolf , Schneider Reinhard
Published: March 2011

In certain cases, Lewis acid catalyzed addition reactions of alkyl halides with alkenes terminate at the 1:1 product stage. This telomerization reaction has been employed to study the efficiency of initiating systems of carbocationic polymerization and the relative reactivities of alkenes towards carbenium ions. A direct determination of addition rate constants is possible in some cases.
Vinyl ethers with a functional group: Living cationic polymerization and synthesis of monodisperse polymers
Authors: Higashimura Toshinobu , Aoshima Sadahito , Sawamoto Mitsuo
Published: March 2011

The living cationic polymerization of vinyl ethers (VEs) having a (polar) functional pendant has been achieved by the hydrogen iodide/iodine (HI/I2) initiating system to give polymers with a very narrow molecular weight distribution (MWD) (Mw/Mn ≤ 1.2). The functional pendants include benzyl, saturated or unsaturated ester, (poly) oxyethylene, and substituted phenoxyl groups. Although these polar groups often disturb cationic vinyl polymerization by inducing chain transfer and termination, the HI/I2 initiator cleanly polymerized the “functionalized” VEs without side reactions, mostly in nonpolar media at low temperatures below −15 °C. The HI/I2‐initiated living polymerization also provided facile methods to synthesize new functional polymers, including water‐soluble polymers, macromolecular amphiphiles, and macromers, all having a narrow MWD. The simplest example is the living polymerization of VEs carrying an oxyethylene chain [‐(CH2CH2O)n‐R] as pendant, which directly yields water‐soluble polymers. The debenzylation of poly(benzyl VE) prepared with HI/I2 led to poly(vinyl alcohol). Polymers of the saturated ester‐containing monomers (2‐acetoxyethyl and 2‐benzoyloxyethyl VEs) were readily hydrolyzed into poly (2‐hydroxyethyl VE), soluble in water and swellable in methanol. This lead was extended to the synthesis of a new amphiphile, poly(cetyl VE‐b‐2‐hydroxyethyl VE), from a block copolymer of cetyl and 2‐acetoxyethyl VEs prepared by their sequential living polymerization initiated with HI/I2. An adduct between HI and 2‐vinyloxyethyl methacrylate [CH3‐CH(I)‐OCH2CH2OCOC(CH3) =CH2] was found to initiate living polymerizations of VEs in the presence of iodine; the products were methacrylate‐type macromers carrying a poly(VE) side chain with a narrow chain‐length distribution.
Some new examples of cationic polymerization
Authors: Schulz Rolf C. , Eifel Heinz‐Werner , Perner Thomas , Mühlbach Klaus
Published: March 2011

Synthesis and properties of cis‐and trans‐methoxyvinyl chloride (MVC) are described. magnified image

Both of these monomers can be polymerized with cationic initiators. From the 13C‐NMR spectra it was concluded, that poly‐(trans‐MVC) is mainly threo‐diisotactic. Copolymerization of cis‐MVC with for instance trans‐MVC or styrene or 1,3‐dioxolane is also described.

The ring‐opening polymerization of 2‐phenyl‐2‐oxazoline under different conditions was investigated. magnified image

The molecular weights, determined by light‐scattering and GPC are in the range between 10 000 and 350 000. A[η] ‐M‐ equation was derived. By hydrolysis with hydrochlorid acid high molecular weight poly(iminoethylene) was obtained.

The ring‐opening polymerization of 1‐azabicyclooctane [4.2.0] (conidine) with different catalysts as well as the properties of the polymers were studied in detail. magnified image

By means of a “mixed‐mechanism technique” well defined styrene‐conidine diblock copolymers are available.
Ring‐opening polymerization of nitrogen– and phosphorus‐containing monomers: Polymerization mechanism and polymer properties
Authors: Kobayashi Shiro , Saegusa Takeo
Published: March 2011

The first part of this paper describes cationic polymerizations of cyclic imino ethers, 2‐oxazolines and 5,6‐dihydro–4H–1,3–oxazines, which proceed via cyclic onium propagating species or via covalently bonded alkyl halide species. In an extreme case, both ionic and covalent species are present in equilibrium and propagate concurrently. The propagation rate constants due to the respective species were determined. A poly(cyclic imino ether) becomes hydrophilic or lipophilic dependent on the substituent of the monomer. Based on this principle, various types of nonionic polymer surfactants have been prepared, e.g., diblock and triblock copolymers, graft copolymers, and surfactants having one 2‐oxazoline chain. The second part is concerned with ring‐opening polymerizations of new eight cyclic trivalent phosphorus monomers. These polymerizations produced phosphorus‐containing functional polymers such as a chelating resin. 31P NMR analyses of polymerization of cyclic phosphinite monomers led to propose a new mechanism of “Electrophilic Ring‐Opening Polymerization”.
Synthesis of copolymers containing acetals
Authors: Reibel L. , Zouine H. , Franta E.
Published: March 2011

The polymerization of cyclic acetals such as dioxolane and dioxepane, initiated by triflic acid in the presence of poly(ethylene oxide)glycol (PEOG), exhibits special features: One can produce triblock copolymers of PEOG and of one cyclic acetal; the molecular weight of the copolymer increases linearly with time like in a living system; a hydroxyl group is found at both ends of the copolymer obtained; macrocycle formation, usually inevitable in large quantity when a classical onium mechanism operates, can be very much reduced and even practically suppressed depending on the experimental conditions. When we tried to prepare a pentablock from the triblock by adding a second acetal under similar conditions (after recovery and purification of the triblock copolymer) we obtained fast transacetalization instead, leading to random placements of the two cyclic acetals, while the PEOG remained as one block, and that only a very small amount of cycles was formed if any. These results are interpreted in terms of multiple transfer reactions of hydroxyl groups onto activated monomer molecules or onto small growing oligomers.
Regularities of cationic polymerization of substituted aziridines
Authors: Ponomarenko V.A. , Chekulaeva I.A. , Lapshina I.V. , Ignatenko A.V.
Published: March 2011

The cationic polymerization of some ordinary N‐ and C‐substituted aziridines, initiated by the methyl etherate of boron trifluoride, shows a typical “temporarily living” character. Kinetic and spectroscopic data on the polymerization of N‐methyl‐aziridine under conditions under consideration as well as molecular mass characteristics of the polymers obtained, testify to the zwitter‐ions as active centres of chain growth. This process is characterized by slow initiation, stationarity of propagation and slow termination with the participation of the polymer chain just after a monomer is used up. Such peculiarity of zwitter‐ion polymerization allows to obtain liniar functional polyaziridines of given molecular mass by termination of the system by means of appropriate nucleophilic compounds.
Anionic ring opening polymerization by alkali metal solutions
Authors: Jedliński Zbigniew , Kowalczuk Marek , Kurcok Piotr
Published: March 2011

The alkali metal solutions were found to be active initiators in the ring‐opening polymerization of β‐lactones. The chemistry of those solutions and their activity as initiators were discussed.
‘Immortal’ anionic ring‐opening polymerization by metalloporphyrin catalyst
Authors: Inoue Shohei
Published: March 2011

Ring‐opening polymerization of epoxide initiated by aluminium porphyrin gives polyether with narrow molecular weight distribution even in the presence of chain transfer agent such as alcohol. This is due to the rapid, reversible exchange between (porphinato)aluminium alkoxide as the growing species and alcohol. As a result, the growing polymer molecules never die, and the reaction may be called ‘immortal’ polymerization.
The active centres' nature in anionic polymerization of polar monomers
Authors: Berger Werner , Adler Hans‐Jürgen
Published: March 2011

In the anionic polymerization of polar monomers the nature of active centres is considerably influenced by the reaction conditions. In a survey, the present state of knowledge is represented and discussed for the polymerization of acrylonitrile. Analogous problems of methyl methacrylate and vinylpyridine polymerization are included in the considerations.
Functionalization of living polymers – results and problems
Authors: Weber Lothar
Published: March 2011

In spite of intensive research, work during the last 20–30 years, even today, the reaction products of living polymers are produced only in small quantities on industrial scale. The expected production of tyres from telechelic polymers was not reached, The difficulty is that the functionalization of living polymers does not result in only one type of functionalized polymer chain but always in a mixture of non‐, mono‐, di‐ and polyfunctionalized compounds. During the last years different technologies for functionalizing living polymers were developed in Buna. The results of these investigations are discussed. Likewise, we show that the functionalized living polymers of ∝‐methylstyrene are of great interest for different industrial uses. A complete technological scheme for the production of telechelic polymers has been developed, which is attached herewith.