bluuebunny/crossref_metadata_2025 huggingface dataset:
Glucose tolerance test results reappraised using recent ADA criteria
Authors: Croxson SCM , Thomas PH
Published: March 2007

Our aim was to examine the sensitivity of the fasting plasma glucose test for diabetes detection using the revised criteria of the American Diabetes Association. The study was a retrospective review of results of glucose tolerance tests performed on suspicion of Type 2 diabetes mellitus and was carried out in the Chemical Pathology Department of a university hospital, Bristol, UK. A total of 599 patients had been referred for glucose tolerance testing on the suspicion of Type 2 diabetes mellitus. Diabetes mellitus was defined by either 2 hour venous plasma glucose ≥11.1 mmol/L, or by elevated fasting venous plasma glucose using both 1985 WHO (7.8 mmol/L) and the lower 1997 ADA (7.0 mmol/L) thresholds. Two hundred and twelve of the 599 subjects had 2 hour plasma glucose≥11.1 mmol/L and, of these, 128 (60%) had FPG≥7.8 mmol/L, a further 31 (15%)had FPG 7.0 to 7.7 mmol/L, and 53 (25%) still had FPG<7.0 mmol/L. Of the remaining 387 subjects with 2 hour plasma glucose <11.1 mmol/L, 26 had FPG≥7.8 mmol/L, and a further 38 had FPG 7.0 to 7.7 mmol/L inclusive.

In a group of subjects with a high prevalence of diabetes (diabetes defined by either elevated 2 hour plasma glucose or elevated fasting plasma glucose), using 1985 WHO criteria revealed a diabetes prevalence of 40% and fasting plasma glucose (7.8 mmol/L) sensitivity of 65%; however, using the 1997 ADA criteria showed a diabetes prevalence of 46% and fasting plasma glucose (7.0 mmol/L) sensitivity of 81% (ie still missed 19% of subjects). There was a group of subjects with significantly elevated FPG using either criteria who did not have an elevated 2 hr value. The ADA criteria increased the prevalence of diabetes from 40% using WHO criteria to 46%. It is important to understand the limitations of these tests if trying to simplify them for routine clinical practice.
Insulin injection techniques. Report from the 1st International Insulin Injection Technique Workshop, Strasbourg, France—June 1997
Authors: Strauss Kenneth
Published: March 2007

Forty diabetes experts — among them investigators who have studied insulin injections for many years — gathered in Strasbourg, France for the first International Insulin Injection Technique Workshop. The objectives of the Workshop were to present known data on injection technique and to outline the future directions of clinical and basic research in this area, in order to define guidelines on injections techniques at the end of the Workshop.
Glycaemic control amongst patients attending a routine diabetes clinic and the impact of intensive insulin regimens in clinical practice
Authors: Pawar BK , Walford S , Singh BM
Published: March 2007

In order to determine the level of glycaemic control attainable and the related benefit of intensive insulin therapy in routine clinical diabetes practice, a cross‐sectional survey of an adult diabetes clinic population was undertaken. We audited 2,066 adult patients with diabetes: age 5±15yr (mean±SD); 1,207 (58%) male; 72% Caucasians; 1,261 (61%) on insulin. Mean HbA1c was 6.7±1.7% (normal <5.5%) with no significant effects of age, sex, racial origin, micro‐ and/or macrovascular complications, but treatment category was significant: HbA1c on diet 6.4±1.6%, on tablets 6.6±1.6% and on insulin 6.8±1.7% (p<0.01). Amongst insulin‐treated patients (age 54±16yr; 56% male; 76% Caucasian), 1,072 (85%) were on conventional insulin regimens and 189 (15%) on intensive insulin regimens. No significant effects were found for age, sex, race, complications or insulin regimen (HbA1c conventional 6.7±1.7% vs intensive 6.9±1.7%) despite the intensive group being younger (56±16yr vs 39±13y, p<0.001). In patients aged <40yr and treated with insulin within one year of diagnosis (n=293, age 31±6yr, 54% male, 83% Caucasians, 105 (36%) on intensive regimens) HbA1c was 6.8±1.7% in conventional vs 7.0±1.7% in intensively treated patients (ns).

We conclude that, in routine practice, conventional and intensive insulin regimens achieve equivalent glycaemic control and are both favourably comparable to the intensively managed group of the DCCT.
Audit of the recommendations of care for pregnant women with diabetes mellitus in the West Midlands, UK
Authors: Dunne FP
Published: March 2007

Following the St Vincent Declaration of 1989, two sets of national guidelines were developed for the care of women with diabetes mellitus during pregnancy. Using a questionnaire survey, this report audits how closely we are adhering to these recommendations in the West Midlands region. There was a 100% response rate to the questionnaire. The audit highlights less than complete compliance with these recommendations in areas of pre‐pregnancy care, availability of joint clinics, routine use of blood glucose meters and Glucagon kits, monitoring for retinopathy and fetal assessment availability of a database. It is possible that non‐compliance to these recommendations may be contributing to the continuing high perinatal mortality stillbirth and congenital malformation rates, which remain two to four times that of the non‐diabetic population.
Healthcare professionals' perceptions of beliefs about health and illness in migrants with diabetes mellitus
Authors: Hjelm K , Isacsson Å , Apelqvist J
Published: March 2007

One hundred and forty nine physicians and nurses working with diabetes care answered a semi‐structured questionnaire with open‐ended questions, about perceived differences between migrant and Swedish patients with diabetes with regard to patients' beliefs about health and illness. Throughout the study, between 12% and 31% of the respondents said they “didn't know”, despite their high contact frequency with migrants. Migrants were perceived as less knowledgeable about bodily functions and diabetes; as attaching more importance to individual factors such as retention of former habits and social relations; as using alternative medicine and drugs to achieve health when ill; and as seeking healthcare mainly in the professional sector. Eighty nine per cent of the physicians and nurses perceived communication difficulties and cultural dissimilarities as affecting compliance, when caring for migrants with diabetes. Migrants were perceived to be different. There is a need for training programmes for healthcare professionals to minimise differences about cultural beliefs and communication.
Reduced pain perception with Pen MateTM an automatic needle insertion device for use with an insulin pen
Authors: Diglas J , Feinböck C , Irsigler K , Winkler F , Egger T , Weitgasser R , Pieber T , Lytzen L
Published: March 2007

The study examined glycaemic control and pain perception in patients using NovoPen® 3 with or without PenMateTM, an automatic injection device, in an open, cross‐over trial. Patients (n=57), who had been injecting insulin for at least 12 months and who had been using Novo Pen®3 for at least six weeks prior to the study, were randomised to use Novo Pen®3 with or without Pen MateTM for six weeks, before crossing over to the alternate system for a further six weeks. Pain perception was recorded night and morning on a 100mm visual analogue scale (VAS). Glycaemic control was monitored by HbA1c measurements and by 4‐point blood glucose profiles. Pain perception was significantly lower with PenMateTM (p=0.005). No statistical difference in HbA1c, blood glucose profiles or adverse events were found between the two systems. Patients found PenMateTM easy to use and 84% said they would recommend the device to a person who is uncomfortable with needles.
A practical guide to polaroid retinal photography
Authors: Taylor Roy
Published: March 2007

The major question frequently resulting from retinal examination is whether or not to refer to an ophthalmologist. This decision is not helped by most books on ophthalmology, which tend to concentrate upon severe, advanced retinopathy. For this reason, a practical guide to interpreting retinal appearances was put together and this pocket‐sized book is now available at cost price.
Diabetic retinopathy. Outcome at five‐year follow‐up of 203 people with diabetes. 2: Analysis
Authors: Khaleeli AA , Fear S , Maitland H , Moloney A
Published: March 2007

In 203 patients attending a diabetes clinic over five years, the death rate was significantly higher (p = 0.005) among those with typical diabetic retinopathy (DR) (12/46; 26%) than among those without diabetic retinopathy (NDR) at 14/157; 9%. This difference remains significant even when adjusted for age and other potential risk factors such as smoking, male sex, hypertension and greater duration of diabetes (see also first of these two articles in the March/April issue of this journal (pages 35–37)).

Congestive cardiac failure, myocardial infarction and stroke were the main causes of death in all people with diabetes in the study. Cancer was another main cause in those with retinopathy.

Differences in HbA1 and lipid measurements between deceased retinopathy and survivors were non‐significant, though the available sample was admittedly small. The most significant difference between surviving and deceased retinopathy was that there were more survivors on insulin (74% v 42%, p = 0.077) but this did not quite attain statistical significance. None of these factors significantly improved our selected logistic model for death rate, which depends only on retinopathy status and age. Eight out of 12 deaths in the DR group occurred in those with mild, non‐eyesight‐threatening, ‘background’ retinopathy plus four with eyesight‐threatening retinopathy, three with maculopathy and one with proliferative retinopathy.

The conclusions drawn from this study are that there is a suggestion that the presence of even mild background retinopathy is associated with a significant risk for future mortality, which persists when confounding established risk factors for mortality are allowed for. The fact that the majority of the deaths were vascular suggests that this subgroup would benefit from further increased efforts at preventing its occurrence and also a more aggressive approach to treating risk factors for vascular disease, when retinopathy of any degree is present.
Health professionals' perceptions of the seriousness of diabetes
Authors: Dunning T , Martin M
Published: March 2007

A cross‐sectional survey was undertaken to ascertain if health professionals rate the severity of NIDDM according to the treatment mode and to establish the reasons for their severity rating. A total of 421 responses were obtained. Most (70%), rated diabetes a serious disease, but there were significant differences in severity rating between the treatment modes, 69% rated insulin treatment serious, compared with 16% rating diet treatment serious (p<0.05). There was a trend for severity to be seen to increase along a continuum from mild (diet), moderate (tablets), to serious (insulin). IDDM was considered to be more serious than NIDDM unless insulin was required. There were significant differences between health professional groups in their severity ratings. Older respondents were more likely to rate diet‐treated diabetes serious (p<0.05). There was a trend, which failed to reach significance, for those with family members with diabetes to rate diabetes serious regardless of the treatment mode. Health professionals believe diet‐treated diabetes is mild.
A practical guide to polaroid retinal photography
Authors: Taylor Roy , Lovelock Lilian , Ryder Bob
Published: March 2007

The major question frequently resulting from retinal examination is whether or not to refer to an ophthalmologist. This decision is not helped by most books on ophthalmology, which tend to concentrate upon severe, advanced retinopathy. For this reason, a practical guide to interpreting retinal appearances was put together and this pocket‐sized book is now available at cost price.
Recurrent hypoglycaemia as the presenting symptom of coeliac disease in a patient with type 1 diabetes
Authors: Bradbury SL , Scarpello JHB
Published: March 2007

We describe a 45 year old person with type 1 diabetes who presented with recurrent hypoglycaemic attacks. These were found to be due to adult onset coeliac disease and, following institution of a gluten‐free diet, her diabetes control stabilised and insulin requirements returned to their earlier levels.
The detection of pedal osteomyelitis in diabetic patients
Authors: Kearney T , Robinson S , Elkeles RS , Pointin K , Cunningham D , Gedroyc W
Published: March 2007

Pedal osteomyelitis in diabetic patients is a serious clinical problem. There is no single, reliable diagnostic tool; plain films are inaccurate, bone scans nonspecific and the role of human pooled immunoglobulin (Hig) scans remains unclear. Magnetic Resonance Imaging (MRI) may prove useful. We therefore aimed to compare these four diagnostic modalities. Thirteen diabetic patients with possible pedal osteomyelitis were recruited. Nine were found to have osteomyelitis based on clinical, microbiological, and surgical findings. All were scanned with all four modalities and the results compared. MRI scans correctly identified all positive cases, with two false positive cases, and excelled in localising infection, allowing for surgical planning. Plain film and Hig scans were less sensitive (6/9 and 7/9 cases, respectively), were difficult to interpret and were poor in localising infection. Bone scans identified eight of the nine cases, with no false positives. In conclusion, this small study suggests that plain films and Hig scans did not confer any additional benefit in the diagnosis of pedal osteomyelitis. Bone scans are a useful screening tool, but when positive an MRI scan should be sought to confirm the diagnosis.
Increasing response rate in data registration and follow‐up of children and adolescents with type 1 diabetes: A prospective population study 1992–97
Authors: Nordfeldt S , Jonsson D , Ludvigsson J
Published: March 2007

Aims

This study considers how a local diabetes team can develop a system for patient data registration and follow‐up to enhance quality control and health economic analysis, and how a high response rate for patient data can be achieved.

Patients and methods

A geographic population of yearly 120–130 intensively treated type 1 diabetes children. <19 years of age was studied. A prospective patient questionnaire monitored: blood glucose and urine testing, insulin doses, acute complications, medications for hypertension and epilepsy, tobacco and snuff use, and any open questions and needs of the patient. This was completed before every visit to the out‐patient department and used as a database for consultation. Data were thereafter registered in regular computer software, and analysed on a yearly basis.

Results

Response rate increased with time to near 100%. There was a time gain for diabetes nurse and physician. Many patients found the questionnaire good for overviewing treatment and easy to complete, whereas some found it was irksome and boring. The total cost of the method was <160 SEK/patient year.

Conclusions

A very high patient data response rate can be achieved over years by a patientsupportive questionnaire integrated in the treatment program. Treatment and outcome analysis can then be performed locally at low costs. The combination of a patient questionnaire with regular hard‐ and software is easy to create, manage and develop. Benefits for diabetes team and patients exceed the total cost.
The use of Dermagraft in diabetic foot ulceration
Authors: Robertshaw DA
Published: March 2007

The use of tissue engineered human donor skin replacement therapy in a longstanding plantar ulceration in a patient with diabetes mellitus is described. The ulceration healed in 14 weeks, having been present for 10 years.
Haematogenous vertebral osteomyelitis and septic arthritis of the wrist complicating septic arthritis of the foot in a diabetic patient
Authors: Abdu TAM , Ritchie DA , Vora JP
Published: March 2007

An elderly female with peripheral diabetic neuropathy presented with a septic arthritis of the left 5th metatarsophalangeal joint. Her condition was further complicated by vertebral osteomyelitis and septic arthritis of the wrist, the latter secondary to the increased local vascularity following a right Colles fracture. Although the plain radiographs of the spine were suggestive of infection, bone scintigraphy was non‐specific. MRI appearances at the L3/4 level were classical for infective spondylitis and, following biopsy, culture confirmed an unusual pathogen—Pseudomonas aeruginosa. The organism was also detected on blood culture and in a swab of the foot ulcer some three months previously. Following appropriate antibiotic therapy, the patient made a full recovery.
Evaluation of extra‐laboratory blood glucose meters: Beyond precision and accuracy
Authors: Day AP , Barrett A
Published: March 2007

Capillary blood glucose monitoring plays an important part in the monitoring of diabetes. There are a large number of different blood glucose meters, each of which have satisfactory analytical performance for monitoring purposes in the hands of experienced personnel. Of less certainty is their performance and acceptability (including ease of use) in the hands of nursing staff, but these factors are more difficult to assess. This study assessed these non‐analytical factors by administering a structured questionnaire to nursing staff who were asked to compare two meters in the clinical setting. Although both meters had adequate analytical performance, there were significant differences in terms of ease of use, especially applying a satisfactory blood sample and speed of operation. These and other user factors could have a significant impact on the successful performance of hospital near patient blood glucose monitoring. This method of non‐analytical method comparison could play an important part in the selection of an appropriate monitoring system.
Education, education and more education!
Authors: Kyne‐Grzebalski D
Published: March 2007

This study explored the difficulties encountered by a group of twelve nurses, qualified for an average of nine and a half years (9 months‐24 years), from two medical and two surgical wards, when implementing diabetes education. A qualitative method, the semi‐structured interview, was used to gain insight into their feelings and perceptions. The findings were discussed in the light of current literature and the opportunities for changes in professional practice considered.

The study showed that, although eight nurses had undertaken postgraduate courses in diabetes and attended diabetes updates, there was still evidence of lack of confidence and the need for further education. The nurses described their role on the ward as multifaceted, with many responsibilities. They were not confident to take sole responsibility for the teaching of their patients with diabetes, without the support and supervision of the Diabetes Specialist Nurse (DSN). The establishment of link nurses, given regular access to the DSN, was suggested as a possible solution. Nurses need continuous updating and contact with the DSN to enable them to implement diabetes education appropriately.
Reasons for non‐urgent referral to a hospital diabetic clinic and the potential unmet need
Authors: Connor H , Collins RJ
Published: March 2007

In a survey of 56 consecutive, non‐urgent referrals to a hospital diabetic clinic, the majority (57%) were because of unsatisfactory glycaemic control. Non‐urgent referrals of patients with ‘at‐risk’ feet (n = 6) were fewer than urgent referrals or admissions for acute foot problems (n = 11). There were very few referrals for proteinuria (n = 1) or dyslipidaemia, and none for inadequately controlled hypertension. There were only two (3.6%) referrals which were considered inappropriate. Extrapolation from these results, and those of a simultaneous district audit of diabetes care, indicates a considerable unmet need for referral for specialist care which, if implemented, would result in a three‐fold increase in non‐urgent referrals.
Characteristics and outcome of ketoacidosis in Libyan diabetic patients
Authors: Lakhdar AA , Elhabroush S
Published: March 2007

The characteristics and outcome of 100 consecutive cases of diabetic ketoacidosis (DKA) in Libyan diabetic patients studied over a six month period are reported. Moderate to severe diabetic ketoacidosis was included (M:51, F:49). Seventy‐eight percent of the episodes were in patients with known diabetes. Ninety‐five percent of patients with DKA were classified as having type 1 diabetes mellitus. Compared to female patients, the male patients had a significantly lower Body Mass Index (BMI) (20.9 vs 22.5 Kg/m2, p < 0.001) and more clinically underweight male subjects were identified (20/51 vs 6/49, p < 0.01). The most common cause of DKA was stopping insulin therapy, which occurred in 41% of the episodes, followed by first presentation and infection. A trend towards more male subjects stopping insulin was observed. Mortality was 2%. We conclude that the majority of cases of DKA in Libyan diabetic patients is potentially avoidable by simple education and is associated with a low mortality. Sex‐related features of patients with DKA are suggestive of a ‘male attitude diabetes syndrome’.
A case of diabetic muscle infarction
Authors: Yung L , Page SR , Kerslake R
Published: March 2007

Spontaneous muscle infarction is a rare complication of long‐standing diabetes, which most commonly involves the thigh. We report a 27‐year old patient with type 1 diabetes who experienced infarction of the anterior compartment of the leg, which resulted in potential nerve injury and a permanent foot drop.
Hypoglycaemia and cardiac arrest
Authors: Burke BJ , Kearney TK
Published: March 2007

Three case histories are described of type 1 (insulin‐dependent) diabetic patients. All suffered cardiac arrests during hypoglycaemic episodes. Mechanisms relating the cardiac arrests to the hypoglycaemia are discussed. The dangers of hypoglycamia to the heart are emphasised.
HbA1c local reference ranges: Effects of age, sex and ethnicity
Authors: Burden M. L. , Basi M. , Burden A. C.
Published: March 2007

Objective: To determine a local HbA1c reference range.

Design: Healthy volunteers recruited into an observational study.

Subjects: 262 healthy volunteers. Subjects were excluded if known to be diabetic or on medication known to interfere with glucose levels or if random capillary blood glucose was >10mmol/L.

Conclusion: Our local reference range for DCA 2000 measurement of HbA1c has now been established and is 5.5% (+/−0.5). Two standard deviations allow the normal range to rise to 6.5%. Significant (if small) differences were seen between sex, age and ethnicity. Districts, particularly those with non‐white populations, should establish local reference ranges for measurement of glycated haemoglobin. This study shows that it is practical to do so.

Results: Reference range was mean 5.5% (+/−0.5). There were differences in ethnicity, sex and age. Ethnicity: Mean HbA1c in which (n=135) was 5.3% (+/−0.4), which was lower than for Indo‐Asians (n=127), which was 5.7% (+/−0.5):p=0.001. Sex: In females (n=140) mean HbA1c was 5.4% (+/−0.45), which was lower than for males (n=122) 5.6% (+/−0.5): p=0.006. Age: For white males aged 20‐44 the mean value was 5.1% compared to a mean value of 5.6% in men >65 years. White females changed from 5.0% at ages 20–44 to 5.4% for >65years. Indo‐Asian females changed from 5.3% at ages 20–44 to 5.7% in women >65 years. However, for Indo‐Asian men aged20‐44 the mean value was 5.6% and remained at 5.6% above the age of 65 years.
Hypoglycaemia with septicaemia: A case report
Authors: Kreth U , Pender S , Kanabar DJ
Published: March 2007

A 6 year old boy with Type 1 diabetes mellitus developed meningococcal septicaemia. The intravenous insulin infusion had to be discontinued for several hours because of hypoglycaemia which seemed unusual in the face of severe septicaemia and shock.
Glycaemic outcome in patients with type 2 diabetes referred to a hospital clinic because of poor control
Authors: Connor H.
Published: March 2007

In a retrospective survey of 24 consecutive referrals to a hospital diabetic clinic of patients with type 2 diabetes and HbA1c > 7.5%, HbA1c at 6–12 months improved in those maintained on oral hypoglycaemics (initial 9.5% ± 1.1%, finl 8.0% ± 1.5%, n=10, p=0.02) and in those who were changed to insulin (initial 9.7% ± 1.4%, final 8.0% ± 1.5%, n=14 p= <0.01). Patients maintained on oral hypoglycaemics were significantly more overweight than those changed to insulin (BMI 35.0 ± 8.2 kg/m2 versus 27.3 ± 5.8 kg/m2, p <0.025). If patients who missed more than 30% of appointments (n=7) are excluded from the analysis, the outcome in HbA1c was similar to that achieved in the intensive arm of the UKPD Study.
Factors associated with diabetes and its control in a newly developed country
Authors: Malik M , Bakir A , Ai‐Hamadi Hind A , Pugh RNH , Hossain MM , Absood GH , Gill GV
Published: March 2007

We have determined factors associated with the control of diabetes mellitus, a leading and emerging public health problem in the United Arab Emirates (UAE). Diabetic patients from the Abu Dhabi Emirate responded to interviewer‐administered questionnaires, including socio‐demographic factors. UAE citizens (49% of patients) showed a female preference for hospital‐based treatment, and had a fasting blood glucose level that was a mean 1.2 mmol/L higher than in South Asian patients (p=0.024). Health centre‐managed patients had over twice the odds of poor diabetic control compared to those treated at hospital (OR 2.47, p=0.001). A positive family history of diabetes was significantly associated with good control (OR 0.39, p=0.001), suggesting that diabetes in the family encourages better care. The findings suggest that hospitals are overburdened with routine management, and that improvements are needed in primary care and in the community‐based approach to diabetes control, especially among the indigenous population.
Acute diabetic ketoacidosis precipitated by substitution of insulin in type 2 diabetes
Authors: Rajbhandari SM , Tesfaye S , Ward JD
Published: March 2007

Diabetic ketoacidosis (DKA) is uncommon in type 2 diabetes, as there is some degree of endogenous insulin present in these patients. We present two patients with insulin treated type 2 diabetes, who developed DKA requiring hospital admission when the insulin treatment was converted to oral hypoglycaemic agents (OHAs). Both made uneventful recovery and insulin treatment was reinstituted. We therefore suggest that, when converting insulin treated type 2 diabetic patients to OHA, they should be monitored carefully for the development of ketonuria and promptly switched back to insulin in order to prevent life‐threatening DKA.
Studies of molecular motions and phase transitions in polymers using the rotating frame magnetic resonance method
Authors: Connor T. M.
Published: March 2007

The concept of the relaxation time in the rotating frame, T1p, is introduced and compared with the more familiar spin‐lattice relaxation time T1. The experimental requirements for measuring T1p are briefly discussed. The relationship between T1 and T1p and molecular correlation times, τc, and activation energies, ΔE, for motions is indicated. T1p data for a number of polymers, i.e. polyethylene oxides, polypropylene oxide, stereoregular forms of polymethyl methacrylate and starch are briefly discussed and compared with other T1p data for polymers in the literature. The advantages of making relaxation measurements in the rotating frame are pointed out and a number of difficulties connected with spin‐diffusion mechanisms and determinations of crystallinity are discussed.
Structure and properties of ethylene—methacrylic acid copolymers and their sodium salts: Dielectric and proton magnetic relaxation studies
Authors: Read B. E. , Carter E. A. , Connor T. M. , Macknight W. J.
Published: March 2007

Dielectric and proton magnetic relaxation data have been obtained for an ethylene‐methacrylic acid copolymer (containing about 4 mole% methacrylic acid units) and its 53% ionised sodium salt. The degrees of crystallinity and percentage ionisation of the samples investigated were estimated by infra‐red methods.

The dielectric results were obtained principally in the frequency range 100 Hz to 10 kHz and at temperatures ranging from 80° to – 120°. A few results are also reported at frequencies down to 0·1 Hz and up to 100 MHz. For the acid copolymer, two dielectric loss regions are observed and these are correlated with the reported mechanical β′‐ and γa‐processes respectively. The partly ionised copolymer exhibits three dielectric relaxation regions which correlate with the mechanical α‐, β‐ and γa‐relaxations respectively. In addition, a dielectric peak appears at about —40° in the presence of absorbed water, a result similar to that found in the polyamides.

The proton magnetic relaxation results were obtained by pulse methods which yielded the spin‐lattice relaxation times T1 (at 30 MHz) and T1p (at kilohertz frequencies) as a function of temperature from −180° to 100°. Two components were generally observed for T1p. For the acid copolymer the β′‐ and γ‐processes have been observed from these results, as well as a lower‐temperature (δ) process which has not been detected by the mechanical or dielectric methods. For the sodium salt the γ‐ and δ‐processes are also found, in addition to a high‐temperature process in the region of the merged α‐ and β‐processes.

The present data are consistent with previous assignments for the β′‐, α‐, β‐ and γ‐processes. The ‘water’ relaxation appears to involve some rotation of water molecules, or of ionic segments to which water molecules are attached, in the proposed ionic domains. The δ‐process is ascribed to the rotations of methyl groups present in the methacrylic acid units.
Crystallinity determination in polymers and a quantitative comparison for polyethylene
Authors: Richardson M. J.
Published: March 2007

A review is given of methods most often used in determining the crystallinity of polymers. In general, emphasis is placed on specific features peculiar to the various techniques rather than experimental aspects. Because of the considerable and increasing use of differential scanning calorimetry, enthalpic methods of crystallinity determination are considered in some detail.

The need for a critical selection of parameters representing the fully amorphous and crystalline states is emphasised. This selection can be made for polyethylene, and results of crystallinity determinations using several methods are given for this polymer. Agreement is generally good for unoriented melt‐crystallised material (the n.m.r. value is, as expected, anomalous). Interfacial effects are therefore negligible and the structure is adequately represented by a simple two‐phase model. Complications arise when polymer is oriented (single crystals grown from solution are included here) and there is little correlation between the various crystallinities.
Characterisation of a new crystallisable polymer
Authors: Allen G.
Published: March 2007

A scheme is outlined for the characterisation of a crystallisable polymer using simple basic techniques. In it, the thermal characteristics such as melting point and stability up to the melting point are examined using a microscope. A range of solvents is selected and simple fractionation procedures are investigated. The solution properties of the fractions are studied by viscometry and light‐scattering. Finally the melting points and glass transitions of the fractions are investigated, mechanical and dielectric loss measurements are made and gravimetric analyses of thermal stability are carried out.

An example of the application of this scheme to a relatively new polymer, polytrifluoroethoxy phosphazene, is discussed and difficulties encountered as the characterisation scheme progressed are outlined.
Ionic conduction in polymer films I. Influence of electrolyte on resistance
Authors: Kinsella E. M. , Mayne J. E. O.
Published: March 2007

Ionic conduction in continuous polymer films is of two types. Inverse conduction occurs when the resistance of the film runs counter to, and direct conduction when the resistance follows, that of the external solution. The two types are interconvertible; the controlling factor is the water content of the film, which is governed by the nature of the polymer, the mode of preparation of the film, and the conditions of exposure.
Influence of solvent on measurement of cohesive energy density of polystyrene
Authors: Cowie J. M. G. , Ranson R. J. , Burchard W.
Published: March 2007

The solubility parameter (δ2) of polystyrene was measured by the maximum [δ] method in four series of solvents which were structurally different. In each case δ2 varied with the solvent series used, from 8·75 to 9·25 (cal/ml)1/2 The enthalpy parameter (XH), which was calculated for polystyrene dissolved in at least one member of each series, was then used to derive δ2, and little or no variation in δ2, with solvent was observed. The average value was δ2 = 9·16 ± 0·1 (cal/ml)1/2 It has been shown that determination of δ2, from [η]max can be solvent‐dependent because of the influence of the entropy term Xs. It was concluded that if reliable values of δ2 are to be obtained, they should be estimated from XH.
Evolution of toxic gases from heated plastics
Authors: Bott B. , Firth J. G. , Jones T. A.
Published: March 2007

A brief investigation has been carried out into the nature and quantity of the toxic gases evolved during the thermal decomposition of polyurethane, urea‐formaldehyde, nylon and acrylonitrile in air and in nitrogen. The weight fractions of the polymers evolved as hydrogen cyanide are given, together with the lowest temperatures at which hydrogen cyanide, carbon monoxide, ammonia and nitrogen oxides are evolved. Apparent activation energies for the evolution of hydrogen cyanide and carbon monoxide have been determined. A brief discussion of the experimental data is given.
Boron difluoride chelates as catalysts for curing epoxy resins
Authors: Chandler J. F. , Dobinson B. , Johnston E. , Jones M. E. B. , Martin R. J. , Stark B. P.
Published: March 2007

BF2‐chelates are powerful polymerisation catalysts for epoxy resins; derivatives of β‐diketones and of β‐ketoamides are especially interesting as ‘latent’ hardeners. Comparison of these metal halide chelates with BF3‐amine complexes in various epoxy systems has shown the chelates to be superior in several respects. Particular advantages are the ease with which reactivity can be varied by choice of chelate structure and by addition of moderators, and the reduced sensitivity to atmospheric moisture during cure. Use of BF2‐Chelates also gives cured products with better electrical properties, and in many cases better mechanical properties, than with BF3‐amine complexes.
Influence of radiation intensity upon photo‐oxidation of unstabilised PVC
Authors: Martin K. G. , Tilley R. I.
Published: March 2007

Films of unstabilised PVC have been exposed to xenon‐arc irradiation at various levels of intensity within a limited temperature range, and the rates of photo‐oxidation have been determined by infra‐red spectroscopy. It has been found that the rate of reaction is directly proportional to radiation intensity measured in absolute units, and that transposition of time and radiation intensity is valid. The consequences of this finding have been discussed in terms of reaction mechanism and acceleration of the time scale for oxidation of PVC under artificial exposures to the xenon‐arc, compared with outdoors exposure to solar radiation at Melbourne and London.
Hot‐melt adhesives based on ethylene‐vinyl acetate copolymer resins
Authors: Raffield P. J.
Published: March 2007

Hot‐melt adhesives based on ethylene‐vinyl acetate (E‐VA) copolymer resins are compared with other important classes of adhesive products, and reasons for the prominence of E‐VA copolymer resins in this field are discussed. Particular emphasis is placed on the influence of the randomly distributed vinyl acetate content on the structure and properties of E‐VA copolymers. Molecular structure is the factor which most strongly influences compatibility of the E‐VA resin with other hot‐melt ingredients.

A procedure for tackling the problem of hot‐melt adhesive formulation is described, and emphasis is placed on the importance of having available simple test procedures for the complete and reliable assessment of adhesive performance.
‘Elasticisation’ and plasticisation of PVC with ethylene‐vinyl acetate copolymers
Authors: Hardt D.
Published: March 2007

Copolymers of ethylene and vinyl acetate (E‐VA) of a certain composition can be used for the improvement of impact properties (elasticisation) of PVC as well as under certain conditions (grafting) for the preparation of flexible PVC (plasticisation). Products of interesting properties are prepared by blending E‐VA (up to ∼ 12%) with PVC or more advantageously by grafting vinyl chloride on special E‐VA types. Graft copolymerisation by the suspension method allows the synthesis of E‐VA/PVC systems in all ratios (up to 80% E‐VA); these polymers are compatible over the whole range in contrast to the blends.

Studies on the grafting efficiency of some monomers show that vinyl chloride can be grafted readily on E‐VA.

The grafting process is performed on a technical scale to give PVC types with E‐VA contents up to 50%. Products with 6–8% E‐VA should be classified as impact‐modified suspension PVC. Flexible types (40–60% E‐VA) have properties of flexible PVC with the plasticiser chemically incorporated, but may also be blended with unmodified PVC to give impact‐improved formulations.

The properties of the elasticised PVC (8% E‐VA) mainly depend on the vinyl acetate (V‐OAc) content of the E‐VA and its molecular weight. Levapren® 450 P (45% V‐OAc; mol. wt. ∼ 100,000), a solution process copolymer, has good elasticising efficiency in blends and graft copolymers with PVC.

PVC/E‐VA products may be processed with or without addition of uncombined PVC into rigid or flexible PVC by the usual methods of PVC technology, e.g. extrusion, injection moulding, blow‐moulding and calendering.

Competitive modifiers, such as acrylonitrile‐butadiene‐styrene copolymers, methacrylate‐butadiene‐styrene copolymers, acrylates or chlorinated polyethylene, are compared with E‐VA. Levapren® 450 P shows high efficiency as an impact modifier even in low concentration, giving good processability and ageing behaviour. Glass‐clear high‐impact PVC cannot be obtained by E‐VA modification.

Some electron microscopy studies to characterise the distribution of E‐VA in the resin phase (PVC) are described; these showed the presence of a two‐phase system.
Vinyl acetate‐ethylene copolymer dispersions
Authors: Reynolds G. E. J.
Published: March 2007

The function of ethylene as a plasticising comonomer for vinyl acetate is reviewed from the historical standpoint and in relation to alternative methods of plasticisation. Both chemical and physical effects are considered. Emulsion polymerisation and the use of aqueous dispersions are covered in some detail, and methods of polymer characterisation are summarised, with particular reference to i.r. and n.m.r. spectroscopy.
Dynamic wetting of glass fibre and polymer fibre
Authors: Inverarity G.
Published: March 2007

To achieve high strength and chemical resistance in glass‐reinforced plastics, it has been found essential to have a good bond between matrix and reinforcement. To obtain this bond it is necessary that good wetting of reinforcement by matrix must occur at some stage in the production cycle.

Modern process developments have reduced the time during which wetting can occur to a few seconds in continuous sheeting manufacture. The wetting stage of this process has been investigated by the observation of dynamic contact angles. The rate of wetting has been found to be controlled by liquid flow and not surface tension at high processing speeds. Breakdown of this flow and intermittent wetting have been observed directly.

When low energy surfaces are wetted by water, a different limiting factor is found. It is observed that a maximum dynamic contact angle is reached at relatively low wetting rates. It is suggested that these maximum angles offer a new means of assessing Zisman's ‘critical surface tension’ (γc) and by an extension of the technique may enable values of spreading pressure (π) to be measured.
Molecular characterisation by electric field light‐scattering
Authors: Jennings B. R.
Published: March 2007

Examination of the intensity of the light scattered from a solution of randomly distributed and oriented molecules, whose major dimensions are of the order of the wavelength of visible light, leads to information about the molecular size. When subjected to electric fields, the molecules become orientated and aligned, thereby changing the polar intensity scattering diagram. Measurements of the intensity changes lead to a host of additional molecular parameters. An outline of the method is given, with particular emphasis being laid on the basic physical principles. Details of the apparatus, the handling of the experimental data and the type of molecular information that can be obtained using direct, alternating and pulsed electric fields are given. Measurements of the equivalent changes in scattered intensity due to d.c. using a.c. fields are probably the most useful as they lead to information on the dipole moments, relaxation time, flexibility and polydispersity of the sample and yet involve little modification to commercial scattering photometers.
Dispersibility of carbon black by polyvinyl alcohol solutions
Authors: Johnson G. A. , Lewis K. E.
Published: March 2007

The dispersibility of carbon black by eight types of polyvinyl alcohol solution has been studied which differed in their degree of hydrolysis (i.e. amount of free acetate groups) and molecular weight. The degree of hydrolysis varied from 80 to 100% and the molecular weight (viscosity average) from 6000 to 40,000. Adsorption isotherms of the polyvinyl alcohol on to the carbon black and contact angles of water on carbon black on to which polyvinyl alcohol had been previously adsorbed were measured. These results are related to the concentration at which dispersion occurs. It is shown that dispersion occurs when the contact angle falls below 90° but that this does not correspond to monolayer coverage of the polyvinyl alcohol on the carbon black. In fact, dispersion occurs at very low levels of adsorption, suggesting that only a low surface coverage is necessary to produce a hydrophilic surface.
Initiator complexes derived from dichlorobiscyclopentadienyl titanium and alkyl aluminium compounds: I. The reduction reaction
Authors: Amass A. J. , Hay J. N. , Robb J. C.
Published: March 2007

A general mechanism of the reduction of dichloro‐biscyclopentadienyl titanium with triethyl aluminium has been derived from a study of the reaction at −70° in toluene and n‐heptane solutions. The reaction products were found to depend on the Al:Ti molar ratio. Each product was examined as active initiators for the homopolymerisation of styrene at 60°.
Initiator complexes derived from dichlorobiscyclopentadienyl titanium and alkyl aluminium compounds: III. copolymerisation
Authors: Amass A. J. , Hay J. N. , Robb J. C.
Published: March 2007

Copolymerisation studies have been made with styrene and 4‐methylpentene‐1 using the soluble initiator system dichloro‐biscyclopentadienyl titanium‐triethyl aluminium. Results confirm that a free radical mechanism rather than a co‐ordinated anionic mechanism is operative.
Initiator complexes derived from dichlorobiscyclopentadienyl titanium and alkyl aluminium compounds: IV. Di‐isobutyl aluminium hydride
Authors: Alexander I. J. , Hay J. N. , Robb J. C.
Published: March 2007

Complexes produced in the reaction of dichloro‐biscyclopentadienyl titanium and di‐isobutyl aluminium hydride (DBAH) have been studied as initiators for the polymerisation of styrene and characterised spectroscopically. In general the complexes do not initiate and the observed dilatometric contractions can be attributed to a reaction between styrene and DBAH. The limited amount of polymerisation observed can be associated with a radical process involved in the reduction of Ti(IV) to Ti(III).
Studies on cation‐exchange resins: I. Chelating properties of cation exchangers prepared from cold extracted commercial cashewnutshell liquid
Authors: Dasare B. D. , Krishnaswamy N.
Published: March 2007

Four weakly acidic cation exchangers have been prepared, one by the polycondensation of cold extracted commercial cashewnutshell liquid (C‐CNSL) with formaldehyde and the other three by the co‐condensation of C‐CNSL with formaldehyde and each of the compounds gallic acid, anthranilic acid and 2‐mercapto‐benzothiazole. The resins have been investigated for the selective uptake of cations from external solutions of different pH. The resin prepared by polycondensation of C‐CNSL and the one prepared by its co‐condensation with gallic acid showed comparatively specific absorption of Fe2+ ions.
Emulsion Polymerisation of Styrene and Vinyl Acetate
Authors: Breitenbach J. W. , Kuchner K. , Fritze H. , Tarnowiecki H.
Published: March 2007

Kinetic data on the emulsion polymerisation of styrene are discussed in the light of the Smith‐Ewart theory as modified by Gardon. It is shown that at least in the beginning of the reaction serious discrepances exist between experimental results and the theoretical concept. An electrolytic effect in cationic emulsifier systems was found. Emulsion polymerisation of vinyl acetate was investigated and the mechanism is discussed. The polymerisation of vinyl acetate in aqueous solution without added emulsifier begins as a true solution polymerisation but very soon changes to a suspension polymerisation. The latex particles formed are an order of magnitude larger than those obtained in the emulsion polymerisation and have a very narrow size distribution. There seems to be a very short period of particle formation in this system.
Continuous emulsion polymerisation of styrene and methyl acrylate
Authors: Gerrens H. , Kuchner K.
Published: March 2007

An investigation of continuous emulsion polymerisation kinetics was carried out using a series of three continuous stirred tank reactors (CSTR), and styrene and methyl acrylate as types of monomer with different solubilities in water.

Steady‐state conversion fluctuations reported in the literature could be suppressed by holding the feed rates constant.

The results obtained are only partly in agreement with the theory proposed by Gershberg & Longfield, who combined the basic assumptions of the Smith‐Ewart theory with steady‐state CSTR kinetics.

An explanation for the deviations from this theory is therefore suggested which takes into account the tendency of relatively water‐soluble monomers to form particles from the homogeneous solution and to undergo so‐called interparticle termination as a result of migration of radicals between the latex particles.
Relationship between specific surface area and pore dimension of high porosity nanoporous silicon – Model and experiment
Authors: du Plessis Monuko
Published: March 2007

The structural properties of high porosity nanoporous silicon were researched with the manufacture of integrated nano‐explosive devices in mind. A three‐dimensional nanoporous layer structural model, consisting of cylindrical crystallites, is proposed. Model parameters are derived from gravimetric techniques and the electrochemical etching of high porosity nanoporous silicon layers. A gravimetric experimental technique is described whereby the pore dimensions and specific surface area of nanoporous regions can be determined. An inverse relationship between pore size and specific surface area is found, with a constant specific surface area times pore diameter product. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)