The differential mediating roles of resilience in the relationship between meaningful living and stress among college students during the COVID-19 pandemic.

The current literature, mostly Euro-American based, indicates that the presence of meaning in life (MIL) improves resilience and lowers stress. However, the differential mediating roles of resilience in the relationship between the search for and presence of MIL, and stress have not been explored. This study aimed to investigate the differential mediating roles of resilience in the relationship between the presence of and search for MIL, and stress among Omani college students amid the COVID-19 pandemic. This cross-sectional study consisted of the Brief Resilience Scale, Perceived Stress Scale 4, and Meaning in Life Questionnaire, as well as socio-demographic questions. A path analysis model was used to examine the hypothesis. A total of 970 Omani college students responded to the questionnaire. Findings indicate that searching for MIL was significantly associated with a high level of stress directly (ß = 0.023; p < 0.001) and indirectly, through a negative effect on resilience (ß = 0.006; p < 0.001). Conversely, the presence of MIL was significantly associated with a decreased level of stress directly (ß = - 0.045; p < 0.001) and indirectly via a positive effect on resilience (ß = - 0.151; p < 0.001). In keeping with the proposed hypothesis, this study contributes to the current knowledge, by extrapolating the effect of searching for MIL on resilience and stress, and culturally re-contextualizing MIL research. University counseling centers could adopt meaning-based strategies to mitigate stress by promoting meaningful living and resilience.

Factors predicting medication adherence among Omani patients with chronic diseases through a multicenter cross-sectional study.

Management of chronic diseases is complex and requires a long-term commitment to therapeutic medications. However, medication adherence is suboptimal. There is limited understanding of factors predicting medication adherence in chronic diseases in Oman. This study aimed to examine predictors of medication adherence (i.e. patient clinical and demographic data, patient-physician relationship, health literacy, social support) among Omani patients with chronic diseases. This study used a cross-sectional correlation design. Data were collected from 800 participants using convenience sampling between December 2019 and April 2020. Arabic versions of the Brief Health Literacy Screening tool, Multidimensional Scale of Perceived Social Support, Patient-Doctor Relationship Questionnaire, and Adherence in Chronic Disease Scale were used to measure study variables. Descriptive statistics, independent t tests, one-way ANOVA, Pearson correlations, and multivariate linear regression were used for analysis. The study found that factors such as the patient-physician relationship, social support, disease duration, employment status, and medication frequency significantly predicted medication adherence. Medication adherence was higher among those who were unemployed, had a better patient-physician relationship, and greater social support. However, medication adherence was lower with longer disease duration and higher daily medication frequency. Additionally, medication adherence was positively associated with perceived social support and the patient-physician relationship, but not with health literacy. In conclusion, the study reveals that patient characteristics, social support, and patient-physician relationships are key factors in predicting medication adherence in patients with chronic diseases in the Middle East. It emphasizes the importance of improving these aspects, considering factors like employment status, disease duration, and medication frequency, and enhancing healthcare provider-patient relationships and social support systems to boost adherence.

Chemically sprayed CdO: Cr thin films for formaldehyde gas detection and optoelectronic applications.

Chromium (Cr) doped CdO films are chemically sprayed and are characterized by their optical, electrical, structural, and microstructural characteristics. The thickness of the films is determined by spectroscopic ellipsometry. The cubic crystal structure with a superior growth along (111) plane of the spray-deposited films is confirmed from the powder X-ray diffraction (XRD) analysis. XRD studies also suggested that some of the Cd2+ ions were substituted by Cr3+ ions, and the solubility of Cr in CdO is minimal, to be around ∼0.75 wt%. The analysis by atomic force microscopy shows uniform distribution of grains throughout the surface, whose roughness is varied from 33 to 13.9 nm concerning Cr-doping concentration. The microstructures from the field emission scanning electron microscope reveal a smooth surface. The elemental composition is examined using an energy dispersive spectroscope. The micro-Raman studies carried out in room temperature endorse the presence of metal oxide (Cd-O) bond vibrations. Transmittance spectra are obtained using UV-vis-NIR spectrophotometer, and the band gap values are estimated from the absorption coefficient. The films show high optical transmittance (>75%) in vis-NIR region. A maximum optical band gap of 2.35 eV is obtained from 1.0 wt% Cr-doping. The electrical measurement (Hall analysis) confirmed the degeneracy nature and n-type semi-conductivity. The carrier density, carrier mobility, and dc-conductivity are increased for higher Cr-dopant percentage. High mobility (85 cm2V-1s-1) is observed for 0.75 wt% Cr-doping. The 0.75 wt% Cr-doping show a remarkable response to formaldehyde gas (74.39%).

Investigate the suitability of g-C3N4 nanosheets ornamented with BiOI nanoflowers for photocatalytic dye degradation and PEC water splitting.

The two-step thermal polymerization and solvothermal approach is used to construct nano heterostructures of FCN and BiOI (bismuth oxeye iodide), both of which are Nobel metal-free materials. This work reports the effect nano-heterostructure on the micro-structural, light absorption capability, PEC properties and pollutant degradation efficiency of the synthesised heterostructures. The addition to that formation of FCN/BiOI nano-heterostructure enhances the solar light absorption. The FCN/BiOI nano heterostructure shows 10 times higher photocurrent density than the BCN nanostructure and 3.8 time higher that FCN. The FCN/BiOI has a high induced photo-current density (20.17 mA/cm2) and H2 evolution rate (3762 µmol h-1 cm-2) under solar light illumination (λ ≥ 420 nm) in comparison with the other. Furthermore, the photocatalytic performance of this material for the breakdown of methyl red dyes was much greater. Under solar light irradiation, the azo dyes were degraded in 90 min. The FCN/BiOI nano-heterostructure has a higher dye degradation efficiency of 97.91%. The rapid transport of photo-induced electrons in the FCN/BiOI nanocomposite is responsible for the improvement in PEC and PC performances. These impressive findings suggest that this nanocomposite might be used to facilitate the PEC water splitting and the PC degradation of MR in the presence of light. The current research provides insight on how to best tailor composition and structure for efficient FCN photo-electrocatalysis water splitting and Methyl red dye degradation.

The Unmet Supportive Care Needs of Omani Women Diagnosed with Breast Cancer.

Objectives: This study aimed to assess the unmet supportive care needs of Omani women with breast cancer (BC). Methods: This cross-sectional study was conducted from November 2020 to February 2021 among 250 adult Omani women diagnosed with BC at Sultan Qaboos University Hospital, Muscat, Oman. An Arabic version of the 34-item Supportive Care Needs Survey-Short Form tool was used to determine perceived unmet supportive care needs across five domains. Results: A total of 181 women participated in the study (response rate: 72.4%). The domain with the highest mean score per item was health system and information (mean score: 3.33), with the greatest unmet need in this domain being information about what the patient could do to help themselves get well (40.9%). The domain with the second highest mean score per item was patient care and support (mean score: 3.04), with the greatest unmet need being for clinicians to be more sincere with the patient (36.5%). Higher total mean scores were reported by women who had visited the hospital four times or more over the two months preceding the study (P = 0.045), those with stage 3 or 4 cancer (P = 0.047) and those who had recently undergone radiotherapy or chemotherapy (P = 0.014). Conclusion: Most unmet supportive care needs fell under the health system and information domain. Healthcare providers in Oman should explore patient concerns and provide sufficient information at various stages of the care process to decrease the anxiety associated with living with cancer.

Medication Adherence and Patients' Characteristics in Chronic Diseases: A National Multi-Center Study.

Chronic diseases constitute a significant threat to health. Worldwide, medication adherence in chronic diseases remains unsatisfactory. Understanding factors affecting adherence is essential. This study examined medication adherence by characteristics of patients with chronic diseases. This cross-sectional study included 800 patients. The Adherence to Chronic Diseases Scale was used to measure adherence. Descriptive statistics and logistic regression was used to examine factors influencing medication adherence. Low adherence was found in 19.5% of the patients, 45% had medium adherence, and 35.5% had high adherence. Logistic regression showed that retired (OR 0.496, 95% CI [0.33-0.75]), having COPD (OR 0.460, 95% CI [0.32-0.67]) and duration of disease ≤5 years (OR 1.554, 95% CI [1.11-2.17]) remain independent predictors for high adherence. Mixed findings regarding the relationship between medication adherence and patients' characteristics were noticed. Patients' characteristics should be examined with the individual population when examining and attempting to improve medication adherence in clinical practice.

Attitudes Towards Cancer Patients: A cross-sectional study of Omani patients and attendees at a university teaching hospital.

OBJECTIVES: Many cancer patients experience social difficulties and feelings of isolation. This study aimed to evaluate patients' and attendees' attitudes towards cancer patients. METHODS: A cross-sectional study was conducted of patients and attendees attending Sultan Qaboos University Hospital (SQUH), Muscat, Oman, from December 2018 to March 2019. RESULTS: A total of 1,190 people participated (response rate: 91.5%). The majority (90.7%) did not express reluctance to help cancer patients. Most agreed that cancer patients were productive (76.2%) and are respected by the public (75.0%). However, many participants (63.1%) felt that cancer patients might face difficulties getting married. Multivariate analysis showed that participants who had a family history of cancer or had previously been a caregiver for cancer patients were more likely to believe that cancer patients could be productive (odds ratio [OR] = 1.92, 95% confidence interval [CI]: 1.31-2.82; P <0.05). Less-educated participants were more likely to believe that cancer patients feared not being productive (OR = 1.49, 95% CI: 1.01-2.19; P <0.05). Male and single participants were more likely to perceive that cancer patients faced difficulties getting married (OR = 1.56, 95% CI: 1.20-2.02 and OR = 1.68, 95% CI: 1.22-2.32, respectively; P <0.05 each). CONCLUSION: Patients and attendees attending SQUH in Oman appeared to have positive and supportive attitudes towards cancer patients, although some felt that cancer patients might encounter social obstacles. Healthcare professionals should consider reassuring cancer patients of such positive sentiments. Governmental and non-governmental organisations should act to promote a supportive environment for cancer patients in Oman.

Preoperative Anemia is Associated with Increased Intraoperative Mortality in Patients Undergoing Cardiac Surgery.

OBJECTIVES: We sought to investigate the incidence of preoperative anemia in cardiac surgery and its association with outcomes. METHODS: A retrospective review of clinical, laboratory, and transfusion data for all patients who underwent cardiac surgery at Sultan Qaboos University Hospital between 2008 and 2014 was performed. Patients were divided into two groups, anemic and non-anemic, with anemia defined as hemoglobin levels < 13 g/dL (males) and < 12 g/dL (females). Clinical variables were compared using chi-square and independent t-test. Factors influencing preoperative mortality were analyzed using multivariate binary logistics regression. RESULTS: A total of 599 patients (69.9% males and 30.1% females) were included in the study; 69.3% underwent coronary artery bypass surgery. Preoperative anemia was found in 76.1% of females and 26.7% of male patients. Rates of intraoperative red blood cell transfusions were higher among anemic patients (75.9% vs. 52.3%, p < 0.001). Anemic patients had a worse risk profile with higher incidence of diabetes mellitus (53.8% vs. 38.9%, p < 0.001), congestive heart failure (51.4% vs. 28.3%, p < 0.001), arrhythmia (16.5% vs. 8.6%, p = 0.004), and cerebrovascular disease (10.0% vs. 4.9%, p = 0.015). In addition, they had a higher risk of overall mortality (6.4% vs. 2.6%, p = 0.023). Preoperative anemia remained a risk factor for intraoperative mortality after logistic regression (odds ratio = 4.08, 95% confidence interval: 1.43-11.66; p = 0.009). CONCLUSIONS: Preoperative anemia in cardiac surgery is independently associated with increased intraoperative mortality and early readmission rates post-surgery.

Efficacy of a Six-Week-Long Therapist-Guided Online Therapy Versus Self-help Internet-Based Therapy for COVID-19-Induced Anxiety and Depression: Open-label, Pragmatic, Randomized Controlled Trial.

BACKGROUND: The COVID-19 pandemic has led to a notable increase in psychological distress, globally. Oman is no exception to this, with several studies indicating high levels of anxiety and depression among the Omani public. There is a need for adaptive and effective interventions that aim to improve the elevated levels of psychological distress due to the COVID-19 pandemic. OBJECTIVE: This study aimed to comparatively assess the efficacy of therapist-guided online therapy with that of self-help, internet-based therapy focusing on COVID-19-induced symptoms of anxiety and depression among individuals living in Oman during the COVID-19 pandemic. METHODS: This was a 6-week-long pragmatic randomized controlled trial involving 60 participants who were recruited from a study sample surveyed for symptoms of anxiety or depression among the Omani public amid the COVID-19 pandemic. Participants in the intervention group were allocated to receive 1 online session per week for 6 weeks from certified psychotherapists in Oman; these sessions were conducted in Arabic or English. The psychotherapists utilized cognitive behavioral therapy and acceptance and commitment therapy interventions. Participants in the control group received an automatic weekly newsletter via email containing self-help information and tips to cope with distress associated with COVID-19. The information mainly consisted of behavioral tips revolving around the principles of cognitive behavioral therapy and acceptance and commitment therapy. The primary outcome was measured by comparing the change in the mean scores of Patient Health Questionnaire-9 (PHQ-9) and General Anxiety Disorder-7 (GAD-7) scale from the baseline to the end of the study (ie, after 6 sessions) between the two groups. The secondary outcome was to compare the proportions of participants with depression and anxiety between the two groups. RESULTS: Data from 46 participants were analyzed (intervention group n=22, control group n=24). There was no statistical difference in the baseline characteristics between both groups. Analysis of covariance indicated a significant reduction in the GAD-7 scores (F1,43=7.307; P=.01) between the two groups after adjusting for baseline scores. GAD-7 scores of participants in the intervention group were considerably more reduced than those of participants in the control group (ß=-3.27; P=.01). Moreover, a greater reduction in mean PHQ-9 scores was observed among participants in the intervention group (F1,43=8.298; P=.006) than those in the control group (ß=-4.311; P=.006). Although the levels of anxiety and depression reduced in both study groups, the reduction was higher in the intervention group (P=.049) than in the control group (P=.02). CONCLUSIONS: This study provides preliminary evidence to support the efficacy of online therapy for improving the symptoms of anxiety and depression during the COVID-19 crisis in Oman. Therapist-guided online therapy was found to be superior to self-help, internet-based therapy; however, both therapies could be considered as viable options. TRIAL REGISTRATION: ClinicalTrials.gov NCT04378257; https://clinicaltrials.gov/ct2/show/NCT04378257.

Eye rubbing in the aetiology of keratoconus: a systematic review and meta-analysis.

PURPOSE: Keratoconus is a potentially blinding condition that slowly deforms the cornea in young people. Despite the increasing prevalence of keratoconus, the exact aetiology of the condition is unknown. This first systematic review examines the evidence of eye rubbing and its association with keratoconus and presents the findings of the meta-analysis. METHODS: Two independent reviewers searched the electronic databases for all potential articles published from 1st of January 1900 to 31st of July 2020 on eye rubbing and keratoconus. The researchers assessed the methodological quality of the studies using the Newcastle-Ottawa scale for observational studies. The assessment for statistical heterogeneity was estimated using chi-square and I-square (I2) tests. A p value of < 0.05 was considered as statistically significant and I2 < 30% as homogenous. Begg funnel plot was used to interpret the asymmetry or small study effects. RESULTS: Eight case-control studies were included in this systematic review. Two studies assessed eye rubbing without odds ratios and thus were excluded. The pooled odds ratios for the six remaining studies included in the meta-analysis was 6.46 (95% CI 4.12-10.1). The study results were heterogenous (I2 = 71.69 [95% CI 35.14-87.88]). All the studies scored moderate quality methodology on the Newcastle-Ottawa scale. Begg funnel plot showed asymmetry supporting heterogeneity. CONCLUSION: Eye rubbing showed consistent association with keratoconus. However, the current evidence is limited to only a small number of case-control studies which present as heterogeneous and of sub-optimal methodological quality. Additionally, the cause-effect temporal relationship cannot be determined. Further studies are needed to address this intricate relationship of eye rubbing and its induction, ongoing progression, and severity of keratoconus.

Knowledge of Risk Factors, Symptoms and Barriers to Seeking Medical Help for Cervical Cancer among Omani Women Attending Sultan Qaboos University Hospital.

OBJECTIVES: This study aimed to assess knowledge and attitudes among Omani woman regarding cervical cancer risk factors and symptoms as well as barriers to them seeking medical help. METHODS: This cross-sectional study was conducted between December 2017 and March 2018 at the Sultan Qaboos University Hospital (SQUH) in Muscat, Oman. A validated Arabic-language version of the Cervical Cancer Awareness Measure questionnaire was used to collect data from 550 Omani women visiting SQUH during the study period. RESULTS: A total of 490 women participated (response rate: 89.1%) in this study. Overall, the women demonstrated low levels of knowledge of cervical cancer risk factors and symptoms (28.5% and 45.0%, respectively). The most frequently recognised risk factor was having many children (36.1%), while the most recognised symptom was unexplained vaginal bleeding (69.8%). Women reported that being too scared was the greatest barrier to seeking medical help (68.0%). Various factors were significantly associated with greater knowledge of cervical cancer signs and symptoms including education level (odds ratio [OR] = 2.85; 95% confidence interval [CI]: 1.0-8.22; P <0.05), income (OR = 4.34; 95% CI: 1.70-11.12; P <0.05), parity (OR = 3.59; 95% CI: 1.38-9.36; P <0.05) and a family history of cancer (OR = 1.71; CI: 1.0-2.90; P <0.05). CONCLUSION: Overall, Omani women demonstrated poor knowledge with regards to cervical cancer; in addition, they identified several emotional barriers to seeking medical help. Healthcare practitioners should reassure female patients to encourage care-seeking behaviour. A national screening programme is also recommended to increase awareness and early diagnosis of cervical cancer in Oman.

Retinoscopy as a Screening Tool for Keratoconus.

PURPOSE: To investigate the validity and reliability of retinoscopy in screening for keratoconus using the rotating Pentacam Scheimpflug camera as the gold standard comparison. METHODS: Patients between the ages of 10 and 30 years who were referred to the outpatient clinic with keratoconus, keratoconus suspect, reduced vision, eye discomfort or frequent change of glasses, or for refraction or refractive surgery, were screened by two independent and masked retinoscopists for the presence of scissoring reflex. Patients then underwent vision testing, slit lamp examination, and Pentacam imaging. A diagnosis of keratoconus by Pentacam was made if the final D index in the Belin and Ambrósio Display was ≥2.69. The results of retinoscopy and Pentacam examinations were compared to assess the validity and reliability of the test. RESULTS: A total of 123 patients (67 male patients and 45 female patients) with a mean age of 21 years ±5.6 (range 10-30 years) comprising 245 eyes were included. There were 87 eyes with keratoconus, and using the Amsler-Krumeich classification, 67.8%, 26.4%, 2.3%, and 3.4% of the eyes had stage I, II, III, and IV, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value of retinoscopy were 97.7%, 79.9%, 70.8%, and 98.4%, respectively. The area under the curve was 0.88 (95% confidence interval, 0.83-0.92). There was excellent agreement between the 2 retinoscopists (Cohen's kappa value 0.84). CONCLUSIONS: Retinoscopy appears to be a very sensitive and reliable test for detecting keratoconus including early disease. Such a test may be implemented in population-based screening programs for keratoconus.

The Effect of Body Mass Index on Functional Outcome of Patients With Knee Replacement.

OBJECTIVE: To investigate the effects of body mass index (BMI) on the rehabilitation process in patients with a recent knee replacement. DESIGN: This retrospective cohort study included all patients admitted to a rehabilitation hospital, with a recent diagnosis of knee replacement and available hospital admission data including height and weight, between 2014 and 2017. SETTING: Rehabilitation hospital. PARTICIPANTS: Study participants included patients who had undergone knee replacement surgery (N=742), with available BMI data. INTERVENTIONS: None. MAIN OUTCOME MEASURES: FIM scores, including FIM change per day (FIM efficiency) by BMI category. RESULTS: The chart review identified 742 patients who had undergone knee replacement surgery, with available BMI data. The identified patients ranged in age from 58 to 85 years, with a mean age of 70 years. Of the patients included in the study, 24 were male, 49 were female, 73 were within the normal weight class, 180 in the overweight class, 189 in the obese class I, 143 in the obese class II, and 157 patients were classified as obese class III. The mean FIM efficiency was highest in the obese class II category (3.96). In a multivariate analysis after controlling for age, obese classes II and III had significantly better FIM efficiency. CONCLUSION: This study did not demonstrate that obesity adversely affects the rate of recovery during hospitalization after knee replacement surgery.

Clinical Profile of Omani Keratoconus Patients: An Experience from a tertiary referral centre in Muscat.

OBJECTIVE: To determine the demographics and associated clinical features of Omani keratoconus patients presenting to the Ministry of Defence Hospital (MODH) in Muscat. METHODS: This is a retrospective, descriptive study whereby the electronic medical records of all Omani keratoconus patients presenting to the MODH between January 2011 and December 2015 were reviewed. Demographic details, corrected distance visual acuity, refraction, corneal topography, pachymetry, and treatment received were all documented. RESULTS: There were 458 new keratoconus patients (257 males, 201 females) comprising a total of 893 eyes with a mean age of 20 years ± 5.6 (standard deviation) (range 6-46 years). On their first visit, 35% of eyes had spectacle-corrected distance visual acuity <0.5 logarithm of the minimum angle of resolution (LogMAR), 38% had central corneal thickness <450 um, and 25% had a mean keratometry more than 53 Diopter (D). According to the Amsler-Krumeich classification, 37%, 30%, 18%, and 16% of eyes classified into stages I, II, III, and IV, respectively. The severity of keratoconus did not correlate with the age of patients (rs = -0.13, P < 0.05). Over the 5-year period of the study, 502 eyes were fitted with rigid gas permeable lenses with 91% achieving the vision of 0.1 LogMAR or better, 22% of eyes underwent collagen cross linking, 3% underwent intracorneal ring segments implantation, and 4% underwent corneal grafting. CONCLUSION: A significant proportion of Omani keratoconus patients seen in the MODH showed advanced disease on their first visit. There was no correlation between severity and age suggesting that keratoconus can progress quickly in our pediatric group. Population-based studies are an important next step. Meanwhile, early detection and timely interventions to limit the burden of the disease are crucial.

Intrauterine Fetal Blood Transfusion: Descriptive study of the first four years' experience in Oman.

OBJECTIVES: Haemolytic disease of the fetus and newborn (HDFN) causes hydrops fetalis. The successful treatment of HDFN has been reported with intrauterine blood transfusion (IUT). This study aimed to describe the initial experience with IUT procedures in Oman. METHODS: This retrospective observational study took place at the Royal Hospital and Sultan Qaboos University Hospital Blood Bank, Muscat, Oman, and included all women who underwent IUT procedures in Oman between March 2012 and March 2016. Gestational and neonatal outcomes were assessed, including complications, morbidity, neurodevelopmental sequelae and mortality. RESULTS: A total of 28 IUT procedures for 13 fetuses carried by 11 women were performed. Gestational age at the time of referral ranged from 13-30 weeks, while the median gestational age at first IUT procedure was 26 weeks (range: 19-30 weeks). Indications for the procedure included HDFN caused by anti-D (n = 6), a combination of anti-D and anti-C (n = 4), anti-K (n = 1) and anti-Jsb (n = 1) antibodies and nonimmune hydrops fetalis due to a congenital parvovirus infection (n = 1). Median fetal haemoglobin levels at the beginning and end of the procedure were 4.6 g/dL and 12.8 g/dL, respectively. Most procedures were transplacental intravascular transfusions through the placental umbilical cord root (71.4%), followed by transamniotic intravascular transfusions (14.3%). The overall survival rate was 61.5%, with five deaths; of these, four were intrauterine and one was an early neonatal death due to non-resolved hydrops and severe cardiac dysfunction. CONCLUSION: As a relatively novel obstetric procedure in Oman, IUT seems to result in a favourable outcome for hydropic fetuses.

Electron paramagnetic resonance imaging for real-time monitoring of Li-ion batteries.

Batteries for electrical storage are central to any future alternative energy paradigm. The ability to probe the redox mechanisms occurring at electrodes during their operation is essential to improve battery performances. Here we present the first report on Electron Paramagnetic Resonance operando spectroscopy and in situ imaging of a Li-ion battery using Li2Ru0.75Sn0.25O3, a high-capacity (>270 mAh g(-1)) Li-rich layered oxide, as positive electrode. By monitoring operando the electron paramagnetic resonance signals of Ru(5+) and paramagnetic oxygen species, we unambiguously prove the formation of reversible (O2)(n-) species that contribute to their high capacity. In addition, we visualize by imaging with micrometric resolution the plating/stripping of Li at the negative electrode and highlight the zones of nucleation and growth of Ru(5+)/oxygen species at the positive electrode. This efficient way to locate 'electron'-related phenomena opens a new area in the field of battery characterization that should enable future breakthroughs in battery research.

Origin of voltage decay in high-capacity layered oxide electrodes.

Although Li-rich layered oxides (Li1+xNiyCozMn1-x-y-zO2 > 250 mAh g(-1)) are attractive electrode materials providing energy densities more than 15% higher than today's commercial Li-ion cells, they suffer from voltage decay on cycling. To elucidate the origin of this phenomenon, we employ chemical substitution in structurally related Li2RuO3 compounds. Li-rich layered Li2Ru1-yTiyO3 phases with capacities of ~240 mAh g(-1) exhibit the characteristic voltage decay on cycling. A combination of transmission electron microscopy and X-ray photoelectron spectroscopy studies reveals that the migration of cations between metal layers and Li layers is an intrinsic feature of the charge-discharge process that increases the trapping of metal ions in interstitial tetrahedral sites. A correlation between these trapped ions and the voltage decay is established by expanding the study to both Li2Ru1-ySnyO3 and Li2RuO3; the slowest decay occurs for the cations with the largest ionic radii. This effect is robust, and the finding provides insights into new chemistry to be explored for developing high-capacity layered electrodes that evade voltage decay.

Li(4)NiTeO(6) as a positive electrode for Li-ion batteries.

Layered Li4NiTeO6 was shown to reversibly release/uptake ∼2 lithium ions per formula unit with fair capacity retention upon long cycling. The Li electrochemical reactivity mechanism differs from that of Li2MO3 and is rooted in the Ni(4+)/Ni(2+) redox couple, that takes place at a higher potential than conventional LiNi1-xMnxO2 compounds. We explain this in terms of inductive effect due to Te(6+) ions (or the TeO6(6-) moiety).

Reversible anionic redox chemistry in high-capacity layered-oxide electrodes.

Li-ion batteries have contributed to the commercial success of portable electronics and may soon dominate the electric transportation market provided that major scientific advances including new materials and concepts are developed. Classical positive electrodes for Li-ion technology operate mainly through an insertion-deinsertion redox process involving cationic species. However, this mechanism is insufficient to account for the high capacities exhibited by the new generation of Li-rich (Li(1+x)Ni(y)Co(z)Mn(1-x-y-z)O2) layered oxides that present unusual Li reactivity. In an attempt to overcome both the inherent composition and the structural complexity of this class of oxides, we have designed structurally related Li2Ru(1-y)Sn(y)O3 materials that have a single redox cation and exhibit sustainable reversible capacities as high as 230 mA h g(-1). Moreover, they present good cycling behaviour with no signs of voltage decay and a small irreversible capacity. We also unambiguously show, on the basis of an arsenal of characterization techniques, that the reactivity of these high-capacity materials towards Li entails cumulative cationic (M(n+)→M((n+1)+)) and anionic (O(2-)→O2(2-)) reversible redox processes, owing to the d-sp hybridization associated with a reductive coupling mechanism. Because Li2MO3 is a large family of compounds, this study opens the door to the exploration of a vast number of high-capacity materials.

V2O5-anchored carbon nanotubes for enhanced electrochemical energy storage.

Functionalized multiwalled carbon nanotubes (CNTs) are coated with a 4-5 nm thin layer of V(2)O(5) by controlled hydrolysis of vanadium alkoxide. The resulting V(2)O(5)/CNT composite has been investigated for electrochemical activity with lithium ion, and the capacity value shows both faradaic and capacitive (nonfaradaic) contributions. At high rate (1 C), the capacitive behavior dominates the intercalation as 2/3 of the overall capacity value out of 2700 C/g is capacitive, while the remaining is due to Li-ion intercalation. These numbers are in agreement with the Trasatti plots and are corroborated by X-ray photoelectron spectroscopy (XPS) studies on the V(2)O(5)/CNTs electrode, which show 85% of vanadium in the +4 oxidation state after the discharge at 1 C rate. The cumulative high-capacity value is attributed to the unique property of the nano V(2)O(5)/CNTs composite, which provides a short diffusion path for Li(+)-ions and an easy access to vanadium redox centers besides the high conductivity of CNTs. The composite architecture exhibits both high power density and high energy density, stressing the benefits of using carbon substrates to design high performance supercapacitor electrodes.