432 Improving the Use of Acute ENT Clinic in a DGH During the COVID19 Pandemic

Aim

The SHO led acute ENT clinic is used to assess and treat a variety of ENT pathology. Following the COVID19 pandemic, the department has seen an increase in referrals for conditions that do not meet departmental guidelines. To meet demand, our clinics were always overbooked and over running as juniors sought help from seniors for more complex referrals.

Method

A quality improvement project was initially set to be performed over a few months; however, due to COVID, data was collected over a year from December 2019 to 2020. We looked specifically at number of patients referred, reason for referral, number of follow-up appointments, senior review required and how COVID affected the running of the clinics.

Results

Compared with the clinic's standard operating procedure, 77.2% of clinics were overbooked and 69.8% of patients had unsuitable referrals. This prompted changes such as increasing clinic capacity by introducing full day clinics and increasing senior support by moving to the outpatient department, then clinics were only overbooked 1% of the time. Other areas for improvement highlighted such as advice given to patients as well as referral to main ENT clinic.

Conclusion

It was clear that the capacity of the acute clinic did not meet demand, and this was needed to ensure patient safety and adhere to ENT UK guidance. We implemented a more stringent referral system to increase patient safety by ensuring patients with appropriate pathology are seen in this clinic or referred to other relevant clinics where they can be seen earlier by seniors.

Weil's Disease from a Local New Orleans Bar

INTRODUCTION

Leptospirosis is a zoonotic infection that typically presents with fever, myalgias, nausea, and vomiting after contact with contaminated waters or infected animals (typically rodents); and their excrements. Conditions favorable to the transmission of leptospirosis are common in LA and, without treatment, leptospirosis can lead to both liver and renal failure, meningitis, pulmonary hemorrhage and ultimately death.

CASE

A 56 year old woman with no past medical history presented to the Emergency Department with weakness, myalgias, jaundice and decreased urine output for one week. On arrival, she appeared septic with a heart rate of 130 and fever. Her exam was significant for significant jaundice and diffuse abdominal pain. Laboratory studies were notable for WBC 14, hemoglobin of 12 and platelet count of 63. Creatinine was 8.5mg/dL with a blood-urea nitrogen of 96mg/dl. Total bilirubin was 19.4mg/dL and direct bilirubin was 13.7mg/dL. AST/ALT were 69/38 U/L, respectively and the alkaline phosphate was 160U/L. The patient was admitted to the hospital medicine wards for sepsis and multi-organ failure. She was started on broad spectrum antibiotics but her clinical condition continued to worsen with progressive decline in her hemoglobin and thrombocytopenia and worsening liver failure. She quickly became anuric necessitating dialysis and developed respiratory distress with bilateral pulmonary infiltrates and hemoptysis. Additional history was obtained from her employer that she works at a local New Orleans bar and had been cleaning out rats from the kitchen. Leptospirosis antibody was sent, which returned as positive. Her antibiotics were de-escalated to IV Ceftriaxone. She made a slow recovery over the next two-week period.

DISCUSSION

Since 1987, there has been an average of 3 cases of Leptospirosis diagnosed per year, most of which have been from southeast LA. This case illustrates the importance of considering the diagnosis of Leptospirosis and Weil's Disease in patients in the southeast region of LA who present with multi-organ failure. In addition, our patient's occupational exposure was key to her diagnosis which emphasizes the importance of a detailed history in clinical decision making and patient outcomes.

NEVER SEEMS TO GROW PAINS: A CASE OF SUSPECTED PSEUDOSEPTIC ARTHRITIS

Pseudoseptic arthritis is an acute inflammatory arthritis found in association with a sterile synovial fluid culture despite white blood cell (WBC) counts >100,000 and >75% polymorph neutrophils. This arthritis occurs most frequently in patients with underlying inflammatory or immune disorders. Early distinction from true septic arthritis can decrease the need for unnecessary antibiotics and improve patient outcomes.

Gene expression alterations at baseline and following moderate exercise in patients with Chronic Fatigue Syndrome and Fibromyalgia Syndrome

OBJECTIVES

To determine mRNA expression differences in genes involved in signalling and modulating sensory fatigue, and muscle pain in patients with chronic fatigue syndrome (CFS) and fibromyalgia syndrome (FM) at baseline, and following moderate exercise.

DESIGN

Forty-eight patients with CFS only, or CFS with comorbid FM, 18 patients with FM that did not meet criteria for CFS, and 49 healthy controls underwent moderate exercise (25 min at 70% maximum age-predicted heart rate). Visual-analogue measures of fatigue and pain were taken before, during and after exercise. Blood samples were taken before and 0.5, 8, 24 and 48 h after exercise. Leucocytes were immediately isolated from blood, number coded for blind processing and analyses and flash frozen. Using real-time, quantitative PCR, the amount of mRNA for 13 genes (relative to control genes) involved in sensory, adrenergic and immune functions was compared between groups at baseline and following exercise. Changes in amounts of mRNA were correlated with behavioural measures and functional clinical assessments.

RESULTS

No gene expression changes occurred following exercise in controls. In 71% of patients with CFS, moderate exercise increased most sensory and adrenergic receptor's and one cytokine gene's transcription for 48 h. These postexercise increases correlated with behavioural measures of fatigue and pain. In contrast, for the other 29% of patients with CFS, adrenergic α-2A receptor's transcription was decreased at all time-points after exercise; other genes were not altered. History of orthostatic intolerance was significantly more common in the α-2A decrease subgroup. FM-only patients showed no postexercise alterations in gene expression, but their pre-exercise baseline mRNA for two sensory ion channels and one cytokine were significantly higher than controls.

CONCLUSIONS

  At least two subgroups of patients with CFS can be identified by gene expression changes following exercise. The larger subgroup showed increases in mRNA for sensory and adrenergic receptors and a cytokine. The smaller subgroup contained most of the patients with CFS with orthostatic intolerance, showed no postexercise increases in any gene and was defined by decreases in mRNA for α-2A. FM-only patients can be identified by baseline increases in three genes. Postexercise increases for four genes meet published criteria as an objective biomarker for CFS and could be useful in guiding treatment selection for different subgroups.

Myalgic encephalomyelitis: International Consensus Criteria

The label 'chronic fatigue syndrome' (CFS) has persisted for many years because of the lack of knowledge of the aetiological agents and the disease process. In view of more recent research and clinical experience that strongly point to widespread inflammation and multisystemic neuropathology, it is more appropriate and correct to use the term 'myalgic encephalomyelitis' (ME) because it indicates an underlying pathophysiology. It is also consistent with the neurological classification of ME in the World Health Organization's International Classification of Diseases (ICD G93.3). Consequently, an International Consensus Panel consisting of clinicians, researchers, teaching faculty and an independent patient advocate was formed with the purpose of developing criteria based on current knowledge. Thirteen countries and a wide range of specialties were represented. Collectively, members have approximately 400 years of both clinical and teaching experience, authored hundreds of peer-reviewed publications, diagnosed or treated approximately 50 000 patients with ME, and several members coauthored previous criteria. The expertise and experience of the panel members as well as PubMed and other medical sources were utilized in a progression of suggestions/drafts/reviews/revisions. The authors, free of any sponsoring organization, achieved 100% consensus through a Delphi-type process. The scope of this paper is limited to criteria of ME and their application. Accordingly, the criteria reflect the complex symptomatology. Operational notes enhance clarity and specificity by providing guidance in the expression and interpretation of symptoms. Clinical and research application guidelines promote optimal recognition of ME by primary physicians and other healthcare providers, improve the consistency of diagnoses in adult and paediatric patients internationally and facilitate clearer identification of patients for research studies.

Nutrition support improves patient outcomes, treatment tolerance and admission characteristics in oesophageal cancer

AIMS

Patients with oesophageal cancer undergoing chemoradiation with curative intent are at high risk of malnutrition and its complications, including increased side effects of treatment. We have developed a nutrition pathway (NP), involving the early then periodic nutrition assessment of all patients presenting to the multidisciplinary oesophageal clinic who were planned to receive definitive chemoradiation.

MATERIALS AND METHODS

Patients were assessed as at 'low', 'moderate' or 'severe' nutrition risk, and were provided with appropriate nutrition intervention ranging from preventative advice (low risk), oral nutrition support (moderate risk) to enteral feeding (severe risk). Outcomes for 24 patients treated before implementation of the NP were compared with those of 24 patients treated using the NP.

RESULTS

Patients managed using the NP experienced less weight loss (mean weight change -4.2 kg +/-6.4 cf. -8.9 kg +/- 5.9, P = 0.03), greater radiotherapy completion rates (92% cf. 50%, P = 0.001), fewer patients had an unplanned hospital admission (46% cf. 75%, P = 0.04), and those that did had a shorter length of stay (3.2 days +/- 5.4 cf. 13.5 days +/- 14.1, P = 0.002).

CONCLUSION

Early and regular nutrition assessment/intervention and a multidisciplinary approach to nutrition care results in improved treatment tolerance for patients with oesophageal cancer receiving chemoradiation.

A distal histidine mutant (H52Q) of yeast cytochrome c peroxidase catalyzes the oxidation of H(2)O(2) instead of its reduction

A H52Q variant of yeast cytochrome c peroxidase (CcP), in which the distal histidine is replaced by glutamine, catalyzes oxidation of H(2)O(2) instead of reduction. This redirection of catalytic action is detected by protein film voltammetry. In the presence of H(2)O(2), wild-type CcP, adsorbed on a graphite electrode, shows a strong catalytic reduction wave commencing at about 0.8V (pH 5.4); by contrast, H52Q does not exhibit this activity but instead shows a catalytic oxidation current at potentials in the region of 0.9 V. The oxidation current is partly suppressed in the presence of tetranitromethane (a superoxide scavenger) and is not observed for other mutants studied, including H52A. The only significant structural change in the H52Q variant is that the Q-52 side chain occupies the space vacated by the H-52 imidazole; specifically, the N-epsilon atom that is believed to transfer a proton and induce O--O cleavage is replaced, to within 0.75 A, by the carbamide-O. Thus, while the weakly basic amide functionality is unable to serve in the reorganization of bound H(2)O(2), it is able to facilitate its oxidation, most obviously by serving as a H-bond acceptor to assist formation of a labile superoxide intermediate.

Consistency of condom use among users of injectable contraceptives

Use of condoms for protection against sexually transmitted diseases (STDs) was examined over a nine-month period among 536 women from 17 clinics in southeastern Texas who had selected the injectable depot-medroxyprogesterone acetate (DMPA) as a contraceptive. Among women who were using condoms prior to receiving DMPA, nearly half said they never or rarely did so after initiating DMPA use; only 18% of all women in the study used condoms consistently while relying on DMPA. Factors associated with consistent condom use were being black (odds ratio of 2.0), being unmarried (odds ratio of 2.2), having a history of STD infection (odds ratio of 1.8), having previously used condoms (odds ratio of 2.7) and having no interest in future childbearing (odds ratio of 1.8). Our data suggest that the majority of users of injectables may not be protected from exposure to the human immunodeficiency virus and other STDs.

Experiences of injectable contraceptive users in an urban setting

OBJECTIVE

To examine method-related experiences and acceptability of depot medroxyprogesterone acetate (DMPA) among women using this contraceptive for the first time.

METHODS

Five hundred thirty-six women who received an injection of DMPA from any of seventeen clinical settings in southeast Texas, United States, were followed for 1 year. At each follow-up visit, patients were asked about their experiences with DMPA during the past 3 months and their plans to use this method in the future.

RESULTS

Amenorrhea, irregular bleeding, and weight gain were the conditions reported most frequently. Reports of amenorrhea, weight gain, and acne or skin problems increased over time, but complaints of longer periods decreased (P < .001). Two pregnancies occurred during the study period. However, of these, one existed before the first injection. Depot medroxyprogesterone acetate's continuation rate at 1 year was 28.6%. Heavier and more frequent bleeding, increased cramping, amenorrhea, weight gain, headaches, depression, and nervousness were more frequent complaints of women who discontinued DMPA (P < .05), whereas lighter and less frequent bleeding were reported more often by those who continued to use this method (P <.05). Women who discontinued use of DMPA were more likely to be married and have a concern about injectable contraceptives than those who continued to use this method.

CONCLUSION

Intolerable side effects and changes in menstrual pattern are the most frequently indicated reasons for discontinuing DMPA use. Our results suggest that DMPA's 1-year continuation rate may be lower than previously reported.

A cross-sectional survey of condom use in conjunction with other contraceptive methods

A cross-sectional survey of 3,136 women attending family planning clinics in Texas was conducted to examine past use of and future plans for use of condoms by partners during sexual intercourse for disease prevention in conjunction with other contraceptive methods. Following the receipt of clinical services, including counseling about family planning and disease prevention, both contraceptive and planned condom use reporting increased for the majority of subjects. However 22% of the sample indicated that they intended to reduce condom use in the future and instead use a contraceptive which protects from pregnancy but not from disease. Condom use was indicated more frequently for those who reported at least one risk factor for HIV, but 17% of those at risk indicated lower future condom use than past use. This suggests that without changes in risk behavior, these women will be at increased risk of HIV or another sexually transmitted disease.

Characteristics of injectable contraceptive users in a low-income population in Texas

Among 600 women at 17 family planning clinics in Texas who expressed interest in using the hormonal injectable depot medroxyprogesterone acetate (DMPA), 536 (89%) actually received the injectable. Thirty percent of the DMPA recipients were younger than 21 and 77% were not married. The average numbers of pregnancies and births were 1.9 and 1.2 per woman; one-third of the women had had at least one abortion. The majority of women receiving DMPA (66%) were using it to space births. Their main sources of information about the method were friends (42%) and health care providers (37%), and the most commonly reported reason for its use was dissatisfaction with previous contraceptive methods.

Characteristics and experiences of American women electing for early removal of contraceptive implants

The study describes the experiences of 430 women who had Norplant(R) contraceptive implants removed prior to the five years of method effectiveness. Each subject was surveyed when the implants were inserted and again at the time of removal. Descriptive data are presented concerning perceptions of the method before insertion and after removal, reactions to the contraceptive and experiences associated with the removal procedure. Subjects' use of Norplant implants ranged from 14 days to 40 months, with a mean of 13.3 and median of 13 months. Over 95% reported changes in menstrual bleeding patterns and 95% experienced other non-bleeding related side effects. Non-bleeding side effects were the most frequently indicated reasons for removal, followed by bleeding changes. The mean removal time was 34 minutes with a median of 25 minutes. Over 48% reported experiencing significant pain during the removal procedure, and 27% stated that the pain was greater than expected. Despite electing for early removal of implants,the majority of women surveyed indicated satisfaction with all aspects of the method save its effect on their overall health. Although method-related side effects were intolerable for most subjects, their overall perception of the method was generally satisfactory.

Comparison of three types of ultrasound transducers in evaluating the amniotic fluid index

The purpose of this study was to determine whether there was good correlation between amniotic fluid index measurements obtained with different types of ultrasound transducer. Women undergoing obstetric ultrasonography for multiple indications between 26 and 40 weeks' gestation had the four-quadrant amniotic fluid index measured with three ultrasound transducers: 3.5-MHz linear, 3.5-MHz sector and 3.5-MHz convex. Pearson product-moment correlation and linear regression analysis were utilized to compare the amniotic fluid index values. Sixty-five women participated in the study. A statistically significant correlation was noted between the three ultrasound transducers evaluated (P < .001). Placental location did not appear to affect the results. Amniotic fluid index values obtained with the sector or convex transducers were as reliable as those obtained with the "gold standard" linear transducer and may be interpreted in the same manner.

The attitudes of clinic staff as factors in women's selection of Norplant implants for their contraception

Medical and counseling staff at 13 family planning clinics in Texas, U.S.A., were surveyed regarding their opinions and level of information about the contraceptive Norplant. These responses were used to assess the relationships between clinicians' information and attitudes about the contraceptive and the use of that method by their patients. No differences were associated with respondents' clinical responsibilities or with their type of professional training. However, significant variations in the numbers of patients receiving Norplant from individual providers, and in the proportion receiving the method from certain clinics, were associated with responses to some attitudinal questions. These findings suggest that the opinions about Norplant held by personnel staffing family planning clinics influence the method selection of their patients.

One-year experience with subdermal contraceptive implants in the United States

Women who received Norplant contraceptive implants from any of fifteen clinical settings in southeast Texas, U.S.A., were followed for one year to determine their reactions to the method. Of 1,385 who enrolled to receive Norplant implants, 1,253 had implants inserted. Side effects were reported by 78% of those receiving implants and 70% described changes in bleeding patterns. Spotting or irregular bleeding, weight gain and headaches were the conditions reported most frequently. Nine pregnancies were reported during the study period. Six of these, however, existed before the implants were inserted. At the one year anniversary, 143 of women receiving implants had had them removed. Those who discontinued method use were less satisfied, reported more side effects and were more likely to have planned to have another child, thus using the method for spacing, or to have had a change in their marital status while they were using the contraceptive. Providers should counsel patients to focus attention on plans for the future in selecting their contraceptive method. In addition, we recommend, as does the product's distributor, that providers confirm that patients are not pregnant prior to inserting implants.

Planned condom use by women with Norplant implants

This research examines the use of condoms to protect from disease women who selected hormonal implants for contraception. After receiving contraceptive implants, subjects were surveyed regarding their past use of condoms and their plans for using them to inhibit the transmission of HIV and other sexually transmitted diseases in the future. Twenty-one percent of women in the sample had used condoms in the past, but did not plan to use them once they have the implants. While decreasing their risk for unplanned pregnancy, they and/or their partners can be expected to experience an increased risk of exposure to sexually transmitted disease. Contraceptive providers must emphasize to their patients the need for protection from disease, in addition to pregnancy, when prescribing contraceptive methods.

Factors associated with the choice of Norplant by women attending subsidized clinics in the US

US women attending family planning clinics in Texas, were surveyed to determine which characteristics, experiences, behavior and specific needs were associated with the selection of the contraceptive Norplant. Race, ethnic origin, age and education were unrelated to choice of method. Increased numbers of previous pregnancies, familiarity with the method, dissatisfaction with previous methods, and sources of information about Norplant were associated with its selection. There was significant variation among the clinics in the proportion of patients to which they dispensed the method. Therefore, clinic selection may have influenced the outcomes of contraceptive decisions.

Characteristics and attitudes of early contraceptive implant acceptors in Texas

In 1991, shortly after Norplant became available in the United States, 678 women who had received the implant from 17 providers in Texas were surveyed. Forty-five percent of these women were under 21 years old. The majority (56%) had tried the implant because they were dissatisfied with their previous contraceptive method. Forty-four percent of the sample indicated that the implant was one of the first contraceptive methods they had used and that they had only recently decided to prevent unplanned pregnancy. The average number of children per woman was 1.2, and one-third of the sample had had at least one abortion. While 37% of the women said they wanted no more children, 63% said they were using the implant as a spacing method. The reasons for choosing the implant and concerns about it varied according to the user's age, educational level and race or ethnic group.

Assessing for abuse: self-report versus nurse interview

Estimates are that 1.8 million women are physically abused each year by their husbands. To prevent abuse and promote physical safety, routine assessment is essential. Planned Parenthood of Houston and Southeast Texas added four self-reported abuse assessment questions to their standard intake form completed by all initial and annual-visit clients. After one month of self-report by 477 women, the prevalence of physical abuse was 7.3%. To compare self-report to nurse interview assessment, the same four questions were asked of 300 women coming to the same clinic for initial or annual visits. The reported prevalence of abuse after a nurse interview was 29.3%.

A correlational analysis of symmetry between the arrowhead and featherhead Müller-Lyer illusions

Correlational methods were used to investigate symmetry of effect for the arrowhead and featherhead versions of the Müller-Lyer figure. Two control figures were compared in the determination of baseline levels for measurement of the illusions: a shaft presented without any inducing context, and a shaft with vertical inducing lines attached. In addition, results based on difference-score measures of the illusions were contrasted with results obtained by partial-correlation techniques. Overall, when one considers the results for either one of the arrowhead or featherhead versions, the evidence favours a common underlying mechanism. However, results across the two versions suggest that the mechanisms for the two versions differ fundamentally. In weighting the different kinds of evidence contributing to this conclusion, methodological issues were raised. By obtaining two judgments for each stimulus figure from a large number of subjects, it was possible to demonstrate not only that conventional difference-score measures of illusions are highly unreliable, but also that they can yield biased results.

Control stimuli in investigations of the acute-angled and obtuse-angled Müller-Lyer illusions

Over the past decade, attention has been drawn to the importance of intertip distance (the distance between the tips of the arrowheads or featherheads) as a possible determinant of the Müller-Lyer illusion. Investigation of this stimulus property for the arrowhead and featherhead components of the Müller-Lyer figure has indicated that the two components exhibit a lack of symmetry, a conclusion supported by other studies using rather different approaches to the investigation of symmetry. This article argues that the control stimuli used in previous investigations are inadequate. It is proposed that in addition to the conventional straight-line control stimulus, in which the standard shaft is stripped of the oblique inducing lines. H-shaped figures in which the inducing lines are vertical should be included. Results are reported of an experiment in which both types of control stimuli are used to investigate the effects of intertip distance, and the spatial separation of that distance from the standard shaft, upon the arrowhead and featherhead figures.

Significance of PRI in Raw and Vulcanized Natural Rubber

The Plasticity Retention Index (PRI) has been developed as an objective test for the oxidizability of raw natural rubber and has recently been associated with the Standard Malaysian Rubber Scheme. Oxidizability as measured by PRI significantly affects behavior of rubber in the factory and in service performance and prior information on this property permits adjustments in vulcanizate recipes and in processing conditions to be made so that the most advantageous balance in properties is achieved.

The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part XII. Effects of Vulcanizing Additives on the Reaction of Sulfur with 2,6-Dimethylocta-2,6-Diene, and Their Bearing on the Mechanism of Sulfur Vulcanization of Natural Rubber

To summarize, we conclude that the course of the interaction of sulfur with an olefin alone is determined principally by the electrophilic reactivity of labile polysulfides and by the reactions of cationic-type intermediates, and that the essential function of zinc salts is to stimulate the reactivity of complementary nucleophilic species. Accelerators of the thiazole-type specifically promote the latter reactivity, as almost certainly do other common vulcanization accelerators, e.g., certain amines, metal dithiocarbamates and xanthates, and thiuram sulfides. It may be noted, for example, that reaction of 2,6-dimethylocta-2,6-diene with sulfur, zinc dibutyldithiocarbamate, and zinc oxide at room temperature, i.e., under conditions where direct sulfur-olefin reaction does not occur, yields a dialkenyl polysulfide and negligible cyclic sulfide (a result also found with tetramethylthiuram disulfide and zinc oxide plus zinc propionate at 140° C), indicative of sulfuration by the nucleophilic mechanism becoming almost fully dominant under especially favorable reaction conditions.

The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part VIII. The Reaction of Sulfur with Mono-Olefins

Earlier Parts of this series reported the partial separation and identification of the complex products of certain sulfur-olefin and related reactions chosen as models for examining the mechanism of vulcanization of natural and synthetic rubbers by sulfur. The main conclusion was that sulfur-olefin interaction proceeds by free-radical chain processes, and this has been quoted elsewhere and widely accepted. Results are now presented which extend and correct the earlier findings and lead to the different mechanistic conclusion that the reactions are polar in type, involving heterolysis of S—S and C—H bonds. This paper and Part XI deal with the products of the reactions of sulfur with mono-olefins and a 1,5-diolefin, respectively, and Part X presents a complementary kinetic investigation, the first for such reactions. All the experimental evidence is collated in Part XI in a general theory of sulfur-olefin interaction.

The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part XI. The Mechanism of Interaction of Sulfur with Mono-Olefins and 1,5-Dienes

Believing an alkenyl alkyl polysulfide to be the major product of sulfurmono-olefin interaction at about 140° and the main constituent of the cyclic monosulfide fraction likewise obtained from 2,6-dimethylocta-2,6-diene to bo the thiacyclohex-3-ene (II), Farmer and his coworkers1 advanced the following free-radical chain mechanism for olefinic sulfuration: (see PDF for diagram) In the special case where the sulfurated radical formed in (2) contains one sulfur atom, alternative reactions to (3) and (4) were proposed, viz., capture of a hydrogen atom, followed by polar or radical addition of the alkenethiol to a second double bond, and this was regarded as the main route to the cyclic monosulfides from 1,5-dienes:

The Reaction of Sulfur and Sulfur Compounds with Olefinic Substances. Part IX. The Reaction of Sulfur with 2,6-Dimethylocta-2,6-Diene

Farmer and Shipley showed that reaction of sulfur with 2,6-dimethylocta-2,6-diene (I) at 140° yields a cyclic monosulfide and a crosslinked polysulfide. No detailed investigation of the structures of these cyclic monosulfide or polysulfide products was undertaken, but it was deduced that the former contained 6-ethyl-2,2,6-trimethylthiaeyclohex-3-ene (VIII) and a compound having vinylidene unsaturation, CH2:CRR′, as apparently revealed by the infrared spectrum, and this has formed part of the evidence on which broad mechanistic conclusions have been based. This reaction has now been re-examined in greater detail; the compositions of the cyclic sulfide and crosslinked polysulfide fractions and their variation with time of reaction have been determined. Results and conclusions differing in important respects from those advanced by the earlier workers have been reached, as reported preliminarily elsewhere.

Oxidation of Organic Sulfides. IV. Autoxidation of Cyclohex-2-Enyl Methyl Sulfide

Cyclohex-2-enyl methyl sulfide readily absorbs up to about 0.3 mole of oxygen per mole at 55° to yield a complex mixture. Cyclohexenyl methyl sulfoxide, 6-methylthiocyclohex-2-enone (VIII), cyclohexenone, cyclohexenol, water, and dimethyl disulfide have been identified and estimated approximately quantitatively. A reaction mechanism consistent with these and other experimental data is presented and discussed. Several new keto-sulfides which were required as reference compounds have been prepared and characterized; the sulfide (VIII) and its 3-methylthioisomer (III) show marked antioxidant activity.

Oxidation of Organic Sulfides. III. A Survey of the Autoxidizability of Monosulfides

The reactivity of a variety of organic monosulfides towards molecular oxygen has been investigated at temperatures from 45° to 75°. Formally saturated sulfides by themselves are inert, allylic acyclic sulfides react initially much faster than comparable unsaturated hydrocarbons, and allylic and vinylic cyclic sulfides are still more reactive. Oxygen absorption is promoted by light, by the free-radical catalyst αα′-azoisobutyronitrile, and by certain metallic compounds, but not by peroxides. The azo compound is sufficiently active to catalyze the oxidation of saturates sulfides having C—H bonds adjacent to the sulfur atom, while aryl alkyl sulfides also respond to photocatalysis. A notable feature of these autoxidations is the self-inhibition or strong retardation which generally becomes apparent at small oxygen uptakes. Certain mechanistic details which can be deduced from the experimental findings are discussed.

The Polymeric Structure of Natural Rubber

From the tree to the vulcanized article, the changes in the elastic properties of natural rubber are dependent on essentially second-order modifications of the parent polymer. Successfully in some ways, less so in others, rubber technologists have learned empirically how to develop advantageous qualities and to prevent or minimize the undesirable ones. This empiricism is inevitable because the chemical reactions which produce the physical changes are so little understood. For example, vulcanization represents the conversion of the chainlike polymer into a cross-linked network, but the nature, number, and distribution along the chain of the cross-links, and their variation with curing conditions and on subsequent aging are largely matters of speculation. In fact, one of the major impediments to scientific rationalization of rubber technology is the inability to interpret common physical observations, e.g., on plasticity, state of cure, deterioration on aging, cracking, in terms of molecular structure. The main chemical attack on the problem in these laboratories has been based on the rigorous, but necessarily long-term, course of first resolving the chemistry of a particular process with the aid of model systems, whereby product analysis and identification can be firmly established, and then determining how rubber behaves when caused to undergo similar reactions in a controlled manner. In other words, attention has been directed to the atomic details of aging, vulcanization, etc., rather than to their significance in modifying polymer structure. Our purpose here is to lay emphasis on the latter approach, first by surveying briefly the main physical changes encountered in rubber technology, and then, stimulated by some very recent work on the nature and degradation of raw rubber, by tracing certain fundamental factors underlying these phenomena.