Trapped O2 and the origin of voltage fade in layered Li-rich cathodes

Oxygen redox cathodes, such as Li1.2Ni0.13Co0.13Mn0.54O2, deliver higher energy densities than those based on transition metal redox alone. However, they commonly exhibit voltage fade, a gradually diminishing discharge voltage on extended cycling. Recent research has shown that, on the first charge, oxidation of O2- ions forms O2 molecules trapped in nano-sized voids within the structure, which can be fully reduced to O2- on the subsequent discharge. Here we show that the loss of O-redox capacity on cycling and therefore voltage fade arises from a combination of a reduction in the reversibility of the O2-/O2 redox process and O2 loss. The closed voids that trap O2 grow on cycling, rendering more of the trapped O2 electrochemically inactive. The size and density of voids leads to cracking of the particles and open voids at the surfaces, releasing O2. Our findings implicate the thermodynamic driving force to form O2 as the root cause of transition metal migration, void formation and consequently voltage fade in Li-rich cathodes.

Cryoglobulins and cold agglutinins for hand arm vibration syndrome

BACKGROUND

Hand arm vibration syndrome (HAVS) is a condition caused by hand transmitted vibration from the use of hand-held vibrating tools or workpieces. The disease affects the vascular, neurological and musculoskeletal systems. The vascular component of HAVS is a form of secondary Raynaud's phenomenon. Other causes of disease must be excluded before attributing the cause to hand transmitted vibration.

AIMS

To evaluate the prevalence, and utility of testing for, cryoglobulins and cold agglutinins in patients with HAVS symptoms.

METHODS

A retrospective cohort study of 1183 patients referred for HAVS clinical assessment at St. Michael's Hospital, Toronto, Canada, between 2014 and 2020. The standard operating procedure at the clinic includes a detailed clinical and exposure history, physical examination, objective investigations and blood tests. Data were retrieved from patient chart review and laboratory investigation results for all cases with cryoglobulin and cold agglutinin testing.

RESULTS

A total of 1183 patients had a serum cryoglobulin measurement. Eleven patients (1%) were positive. Seven positive results were 'low titre' (1% positive) and the other four results were 2%, 6%, 9% and 18%. The patient with a 9% positive cryoglobulin titre had previously diagnosed Sjögren's syndrome. There were no positive cold agglutinin tests in the 795 patients tested.

CONCLUSIONS

Routine testing for cryoglobulins and cold agglutinins in patients with HAVS symptoms is not recommended because test positivity rates are negligible. Testing may be considered if the clinical history or routine blood investigations suggest evidence of underlying cryoglobulinaemia or cold agglutinin disease.

Covalency does not suppress O2 formation in 4d and 5d Li-rich O-redox cathodes

Layered Li-rich transition metal oxides undergo O-redox, involving the oxidation of the O²⁻ ions charge compensated by extraction of Li⁺ ions. Recent results have shown that for 3d transition metal oxides the oxidized O²⁻ forms molecular O₂ trapped in the bulk particles. Other forms of oxidised O²⁻ such as O₂²⁻ or (O–O)ⁿ⁻ with long bonds have been proposed, based especially on work on 4 and 5d transition metal oxides, where TM–O bonding is more covalent. Here, we show, using high resolution RIXS that molecular O₂ is formed in the bulk particles on O^2‒ oxidation in the archetypal Li-rich ruthenates and iridate compounds, Li₂RuO₃, Li₂Ru_0.5Sn_0.5O₃ and Li₂Ir_0.5Sn_0.5O₃. The results indicate that O-redox occurs across 3, 4, and 5d transition metal oxides, forming O₂, i.e. the greater covalency of the 4d and 5d compounds still favours O₂. RIXS and XAS data for Li₂IrO₃ are consistent with a charge compensation mechanism associated primarily with Ir redox up to and beyond the 5+ oxidation state, with no evidence of O–O dimerization.

In this work, authors show that O-redox in 4d and 5d transition metal oxides involves the formation of molecular oxygen trapped in the particles. These results are in accord with observations in 3d oxides and show that the greater covalency of the 4d and 5d oxides does not stabilise peroxo-like species.

Redox Chemistry and the Role of Trapped Molecular O2 in Li-Rich Disordered Rocksalt Oxyfluoride Cathodes

In the search for high energy density cathodes for next-generation lithium-ion batteries, the disordered rocksalt oxyfluorides are receiving significant attention due to their high capacity and lower voltage hysteresis compared with ordered Li-rich layered compounds. However, a deep understanding of these phenomena and their redox chemistry remains incomplete. Using the archetypal oxyfluoride, Li₂MnO₂F, we show that the oxygen redox process in such materials involves the formation of molecular O₂ trapped in the bulk structure of the charged cathode, which is reduced on discharge. The molecular O₂ is trapped rigidly within vacancy clusters and exhibits minimal mobility unlike free gaseous O₂, making it more characteristic of a solid-like environment. The Mn redox process occurs between octahedral Mn³⁺ and Mn⁴⁺ with no evidence of tetrahedral Mn⁵⁺ or Mn⁷⁺. We furthermore derive the relationship between local coordination environment and redox potential; this gives rise to the observed overlap in Mn and O redox couples and reveals that the onset potential of oxide ion oxidation is determined by the degree of ionicity around oxygen, which extends models based on linear Li-O-Li configurations. This study advances our fundamental understanding of redox mechanisms in disordered rocksalt oxyfluorides, highlighting their promise as high capacity cathodes.

Frameless stereotactic radiosurgery for the treatment of primary intracranial tumours in dogs

Stereotactic radiosurgery (SRS) is a procedure that delivers a single large radiation dose to a well-defined target. Here, we describe a frameless SRS technique suitable for intracranial targets in canines. Medical records of dogs diagnosed with a primary intracranial tumour by imaging or histopathology that underwent SRS were retrospectively reviewed. Frameless SRS was used successfully to treat tumours in 51 dogs with a variety of head sizes and shapes. Tumours diagnosed included 38 meningiomas, 4 pituitary tumours, 4 trigeminal nerve tumours, 3 gliomas, 1 histiocytic sarcoma and 1 choroid plexus tumour. Median survival time was 399 days for all tumours and for dogs with meningiomas; cause-specific survival was 493 days for both cohorts. Acute grade III central nervous system toxicity (altered mentation) occurred in two dogs. Frameless SRS resulted in survival times comparable to conventional radiation therapy, but with fewer acute adverse effects and only a single anaesthetic episode required for therapy.

Preventable exposure to trimethyl tin chloride: a case report

Trimethyl tin chloride (TMTC) is a highly toxic organotin compound that affects four main target organs: the brain, liver, immune system and skin. Exposure can occur by inhalation, ingestion or direct skin absorption. Trimethyl tin is but one of many hazardous substances with potentially serious health consequences to which individuals working in research laboratories may be exposed. We report a preventable case of TMTC exposure. Better understanding of the Canadian Workplace Hazardous Materials Information System (WHMIS) legislation and its applicability to the research laboratory situation would prevent such unnecessary exposure to hazardous substances.

Dermatitis in a particleboard manufacturing facility

Exposure to wood dust and other chemicals used in particleboard manufacture may cause contact dermatitis. To assess the prevalence and nature of skin complaints in the refining and drying department of a particleboard manufacturing facility following introduction of a new process, workers were assessed by a physician, using a standardized questionnaire concerning symptoms, past and family history, workplace exposures, and use of protective equipment. Cutaneous examination and patch testing were then performed. Questionnaire results showed that workers complained of rash, nasal and eye irritation, as well as cough and bothersome odours. Cutaneous examination identified a heterogeneity of skin problems, with dermatitis being mainly irritant rather than allergic. Quaternium-15 (Dowicil 200) was the only allergen to which more than 1 individual reacted. Aside from the odours, exposure to wood dust could account for the other reported symptoms. Allergic reactions on patch testing were few and did not explain the dermatitis; most skin reactions were irritant. Recommendations to the company included improved dust control, through ventilation and personal hygiene measures, as well as protective clothing. The investigation highlights how the introduction of a new process may focus attention on health complaints that have been present for some time before.

Occupational health and safety management systems in the Canadian pulp and paper industry: methods of auditing

The Canadian Pulp and Paper Association has developed eight "Guiding Principles for Management of Occupational Health and Safety" (OH&S) for its member companies. As part of a study to assess member companies' OH&S activities, an on-site audit was performed for 11 sites. The audit assessed five key components of a management system for a number of OH&S activities. Management-system components more likely to be in place included system ownership and goals and procedures, whereas measures of performance, a review of measures, and corrective action were less likely to be present. Environmental surveillance and injury reduction were most actively monitored, as indicated by the number of measures of performance relating to these activities. The auditing process demonstrated leadership and communicated the OH&S priorities of the Canadian Pulp and Paper Association to the sites.

Prevalence of upper extremity symptoms and possible risk factors in workers handling paper currency

The prevalence of upper extremity symptoms in the workforce is high, particularly in industries characterized by forceful, repetitive or awkward movements. A study was undertaken to assess the prevalence of upper extremity symptoms in bank workers in a paper currency processing operation and to examine the role of possible risk factors for these complaints. Thirty-nine workers of a total workforce of 47 were assessed with a questionnaire and physical examination. The questionnaire collected information about demographics, health status, symptom reporting, psychosocial work stressors and other work exposure characteristics. Overall, 59% of the workers reported having significant work-related upper extremity musculoskeletal symptoms in the preceding year, including 49% with neck and shoulder symptoms and 49% with arm and wrist symptoms. In this study the key predictive factor for upper extremity musculoskeletal symptoms was psychological job demands. The workers had similar ergonomic stressors (with little gradient of exposure) and therefore our results do not contradict the importance of ergonomic factors in the development of upper extremity symptoms. However, the results do suggest that within a group exposed to similar ergonomic stressors, psychological job demands may be an important factor associated with musculoskeletal symptoms.

Characteristics of occupational medicine practitioners and practice in Canada

To obtain baseline information with respect to occupational medicine practice in Canada, a questionnaire survey of members of the Occupational and Environmental Medical Association of Canada was carried out by mail in 1993. One hundred eighty-six responses were received (56% of the membership). The average age of the respondents was 49.5, 12% were female, and 55% worked full-time in occupational medicine. Practice types included corporate settings (58%), clinics (23%), government agencies (14%), worker's compensation boards (7%) and academic settings (5%). Sixty percent had some formal training in occupational medicine, and 46% had occupational medicine certification by either the Royal College of Physicians and Surgeons of Canada, the Canadian Board of Occupational Medicine, or the American Board of Preventive Medicine. Younger physicians were more likely to be female and have gone directly into occupational medicine. Women were more likely to be working full-time in occupational medicine but worked fewer hours per week. Those physicians with specialty qualifications were older and more likely to be working full-time in occupational medicine and be active in professional activities. The Association intends to continue surveying its members on a triennial basis, identifying trends in the practice profiles and continuing education needs.

Investigation of factors affecting mass psychogenic illness in employees in a fish-packing plant

This study of the factors affecting the development of mass psychogenic illness (MPI) was carried out in a large fish-packing plant in New Brunswick, Canada. A total of 269 out of 270 plant employees (99.6%) participated in the study and of these, 208 cases were affected with symptoms of MPI and 61 controls were unaffected over a period of 2 1/2 months. A questionnaire was administered to participating employees to collect information about symptoms, demographic factors, work history, pre-existing medical problems, potential workplace triggering exposure factors, and various psychosocial factors. Multiple logistic regression indicated that the main factors associated with MPI, in decreasing order of importance, were skill creation in the job, odor perception, and female sex. Management of this incident required reassurance of employees that there was no hazardous exposure in the plant as well as recognition of the need to reduce underlying sources of stress in the work environment.

Peripheral sensory neuropathy associated with 1,1,1-trichloroethane

A case is described of peripheral sensory neuropathy in a woman who had daily exposure to 1,1,1-trichloroethane, used as a degreasing agent. Although previous reviews of the health effects of 1,1,1-trichloroethane have not indicated long-term neurotoxicity, there are recent animal studies that suggest chronic central neurotoxic effects and previous case reports of peripheral neuropathy in three exposed workers in one plant. Our case provides additional evidence that 1,1,1-trichloroethane exposure may be associated with peripheral sensory neuropathy. Reporting of similar cases is encouraged and investigation of the neurotoxic effects of 1,1,1-trichloroethane is recommended.

Factors affecting plasma aluminum concentrations in nonexposed workers

In this study, the distribution and determinants of plasma aluminum concentrations were examined in 71 office employees not occupationally exposed to aluminum. The samples were analyzed by Zeeman graphite furnace atomic absorption spectroscopy and were found to be log normally distributed. After using the International Federation of Clinical Chemistry (IFCC) recommended procedure for removal of likely aberrant values, the 95th percentile value was 198 nmol/L (90% CI:165-238); when those using antacids were also excluded, the 95th percentile value fell to 175 nmol/L (90% CI:147-208). Multiple regression analysis indicated that the factors most predictive of log plasma aluminum were the batch in which the sample was analyzed and the use of antacids containing aluminum. The statistical significance of the batch variable likely indicates the well-recognized problem of contamination in sampling and analyzing aluminum.

Health effects of Halon 1301 exposure

An accidental discharge of a Halon 1301 system is reported. Thirty-one workers were assessed, 22 who were present at the time of the discharge, and 9 who worked the next shift. The incident was complicated by a small Freon-22 leak several hours later. Throat, eye, and nasal irritation and lightheadedness were reported by the majority of workers. Workers present during the halon discharge reported significantly more lightheadedness, headache, voice change, cough, and a fast heartbeat than did those who worked the later shift. These differences were significant even after correcting for confounding factors such as age, sex, and sense of anxiety at the time of the incident. The possible causes for the irritant symptoms include breakdown products of Halon 1301 and Freon-22 or contaminants from the halon discharge system. Although these irritant effects may not be an effect of Halon 1301 alone, they may occur in these discharge situations, and workers should be advised of this possibility. The possible cardiac and central nervous system effects also should be considered. The importance of a clear-cut protocol to deal with such incidents as well as worker education are discussed.

Evaluation of the audioscope in an industrial setting

In this study, the findings of a 25 dB hearing level Welch Allyn Audioscope test at 0.5, 1, 2, 4 kHz were compared with the standard of conventional pure-tone audiometry in 228 newly hired construction workers. The sensitivity for all frequency-specific comparisons combined was found to be lower than in previous studies done in a nonoccupational setting. After correction for sampling bias, the specificity for all frequencies combined was well within the range reported in other studies. Only 1.9% of ears (1/53) that were able to hear all four audioscope frequencies were found by conventional audiometry to have clinically important hearing loss defined as a 25 dB hearing level averaged over the speech frequencies. Hence, the audioscope can be used as a rapid initial test in workers who otherwise would not have access to hearing screening.

Work-related toxic epidermal necrolysis?

A case of toxic epidermal necrolysis is described in an employee of a company that carries out plastic extrusion using various resins, including cellulose acetate, co-polyester, polyvinyl chloride, acrylonitrile-butadienestyrene, and polyethylene. Air sampling during normal operating conditions indicated only trace amounts of hydrogen chloride and the plasticizer diethylphthalate. However, pyrolysis products of resin plugs could include compounds such as formaldehyde, acrylonitrile, and chlorinated hydrocarbons that have been associated with previous case reports of either erythema multiforme, Stevens-Johnson syndrome, or toxic epidermal necrolysis. The development of toxic epidermal necrolysis in this worker was directly preceded by exposure to a vapor from a machine used to dry cellulose acetate. The problems in determining work relatedness and advising about return to work are discussed.

Medical management of three workers following a radiation exposure incident

The medical management of three individuals involved in an exposure incident to whole-body radiation at a nuclear generating plant of a Canadian electrical utility is described. The exposure incident resulted in the two highest whole-body radiation doses ever received in a single event by workers in a Canadian nuclear power plant. The individual whole-body doses (127.4 mSv, 92.0 mSv, 22.4 mSv) were below the threshold for acute radiation sickness but the exposures still presented medical management problems related to assessment and counseling. Serial blood counting and lymphocyte cytogenetic analysis to corroborate the physical dosimetry were performed. All three employees experienced somatic symptoms due to stress and one employee developed post-traumatic stress disorder. This incident indicates that there is a need in such radiation exposure accidents for early and continued counseling of exposed employees to minimize the risk of development of stress-related symptoms.

Occupational exposure of electrical utility linemen to pentachlorophenol

Occupational exposure to pentachlorophenol (PCP) for a crew of electrical utility linemen was monitored over a 6-month period by using total PCP in urine per gram of creatinine as a biological monitoring parameter. Urine samples were collected from three groups: A, B, and control, at a 4-week frequency during 1989. Group A was required to use new gloves after each 4-week work period; Group B changed gloves on a need basis as per normal operating procedure. The control group consisted of members of the administrative office staff who were not occupationally exposed. The used gloves returned by Group A were monitored for contamination. On the basis of analysis of the collected data the following conclusions were noted. (1) The linemen experienced a seasonal exposure pattern with exposures peaking in July and August. This seasonal effect was also observed with glove contamination data. (2) The glove contamination levels were significantly associated with urine PCP concentrations when both these variables were expressed as geometric means for the individuals in Group A. Inclusion of work experience as an additional variable enhances this association. Less experienced linemen tended to perform more activities with higher current exposure and had higher urine and glove PCP measurements and higher correlations between these variables than more experienced linemen. (3) Over the study period, the difference in long-term exposures of Group A and Group B linemen was not statistically significant. (4) The long-term individual exposures, calculated as the geometric mean of each individual's sequential sample readings, were all below the biological monitoring guideline value of 1000 micrograms PCP/g creatinine.

The Effect of Stream Cleaning on Salmonid Habitat and Populations in a Coastal Oregon Drainage

Habitat conditions and use by anadromous salmonids were evaluated in five reaches of Upper Lobster Creek, a major stream system in the central Oregon Coast Range, to determine the effect of different levels of stream cleaning. Stream clearance associated with post-World War II logging practices and a 100-year flood event that occured in 1964 severely altered channel configurations and loading patterns of large woody debris. This caused the subsequent removal of log jams. An uncleaned reach had large amounts of woody debris and the highest density of pools, greatest percentage of off-channel habitat, and highest salmonid use. In contrast, a totally cleaned reach had the lowest density of pools and lowest salmonid use. Rehabilitated sections of a reach that had been partially cleaned showed increases in density of pools and salmonid use compared to the remainder of the partially cleaned reach. Retention of standing timber in the riparian zone and maintenance in instream accumulations of large woody debris is recommended to allow streams to reach their productive potential for anadromous salmonids. West. J. Appl. For. 2(3):84-87, July 1987.