Mixed Effects Research Articles

A sequential multiple assignment randomized trial of symptom management for cancer survivors during treatment and their informal caregivers.

Many cancer survivors and their informal caregivers experience multiple symptoms during the survivor's treatment. Test relative effectiveness and optimal sequencing of two evidence-based interventions for symptom management. In this sequential multiple assignment randomized trial (SMART), survivors of solid tumors with elevated depression or anxiety and their caregivers as dyads were initially randomized after baseline assessment in a 3:1 ratio to the Symptom Management and Survivorship Handbook (SMSH, N = 277 dyads) intervention or SMSH plus 8weeks of telephone interpersonal counseling (TIPC, N = 97 dyads). After 4weeks, survivors who were not responding (no improvement or worsening score on depression and/or anxiety item) to SMSH only and their caregivers were re-randomized to continue with SMSH alone (N = 44 dyads) to give it more time or to SMSH + TIPC (N = 44 dyads). Mixed effects and generalized linear models compared severity of depression, anxiety, and a summed index of 16 other symptoms over weeks 1-13 and week 17 between randomized groups and among three dynamic treatment regimes (DTRs). Dyads received SMSH only for 12weeks (DTR1); SMSH for 12weeks with 8weeks of TIPC added from week 1 (DTR2); and SMSH for 4weeks followed by the combined SMSH + TIPC for 8weeks if no response at 4weeks (DTR3). Survivors randomized initially to SMSH alone had significantly lower anxiety over weeks 1-13 compared to those randomized to the combined SMSH + TIPC. In comparing DTRs, survivor's anxiety was significantly lower at week 13 for DTR1 compared to DTR2 with no other main effects for survivors or caregivers. Exploratory moderation analyses indicated a potential benefit of adding TIPC for caregivers of non-responders with elevated baseline symptoms. SMSH + TIPC did not result in better symptom outcomes at week 17 than SMSH alone. Lower intensity SMSH may improve depression and anxiety symptoms for most survivors and their caregivers. Clinicaltrails.gov ID number, NCT03743415; approved and posted on 11/16/2018.

The evolution of subjective cognition after meditation training in older people: a secondary analysis of the three-arm age-well randomized controlled trial

ABSTRACT Aging is associated with cognitive changes, even in the absence of brain pathology. This study aimed to determine if meditation training, by comparison to active and passive control groups, is linked to changes in the perception of cognitive functioning in older adults. One hundred thirty-four healthy older participants from the Age-Well Randomized Clinical Trial were included: 45 followed a meditation training, 45 a non-native language training and 44 had no intervention. Subjective cognition was assessed at baseline and following the 18-month intervention period. Perception of attentional efficiency was assessed using internal and external Attentional Style Questionnaire (ASQ) subscale scores. Perception of global cognitive capacities was measured via the total score of Cognitive Difficulties Scale (CDS). Deltas ([posttest minus pretest scores]/standard deviation at pretest) were calculated for the analyses. Generalized mixed effects models controlling for age, sex, education and baseline scores revealed that meditation training decreased the vulnerability score toward external distractors measured by the ASQ compared to non-native language training. However, no between-groups differences on ASQ internal or CDS total scores were observed. Results suggest a beneficial effect of meditation practice on perceived management of external distracting information in daily life. Meditation training may cultivate the ability to focus on specific information (e.g., breath) and ignore stimulation from other kinds of stimuli (e.g., noise).

Carotid web catheter angiography hemodynamic parameters

BackgroundCarotid web (CaW)-related contrast stagnation on digital subtraction angiography (DSA) may be a marker supporting the pathophysiological theory of stasis and thrombosis/embolization. We aim to assess the correlation between DSA...

Youth Gang Involvement and Long-Term Offending: An Examination into the Role of Psychopathic Traits

Most policies to combat gang criminal behavior are rooted in deterrence and punitive strategies. This is fueled by moral panic, a get tough on crime rhetoric, and a lack of understanding for the psychological factors that may influence this behavior. Further, the extant literature has consistently observed that gang membership is associated with increased criminal behavior. In an effort to promote and shift away from punitive approaches in response to gang delinquency, the current study investigates the role psychopathic traits have in violent and property offending, longitudinally, in a sample of gang-involved youth. The study implemented count mixed effect models to investigate the topic longitudinally in waves 3, 5, 7, 8, 9, 10, and 11, while controlling for other variables with violent and property offending frequency. The current study found that some psychopathic traits are associated with offending behavior, longitudinally, in gang members and youth with a history of gang involvement. The findings suggest that gang intervention strategies should include empirically supported programs for treating psychopathic traits in gang identified youth to reduce involvement in delinquent behavior. Further, practitioners, researchers, and policymakers should collaborate to develop more empirically supported strategies to reduce and prevent gang delinquent behavior from an empathetic lens.

A new kernel two-parameter prediction under multicollinearity in partially linear mixed measurement error model

A Partially linear mixed effects model relating a response Y to predictors ( X , Z , T ) with the mean function X T β + Zb + g ( T ) is considered in this paper. When the parametric parts' variable X are measured with additive error and there is ill-conditioned data suffering from multicollinearity, a new kernel two-parameter prediction method using the kernel ridge and Liu regression approach is suggested. The kernel two parameter estimator of β and the predictor of b are derived by modifying the likelihood and Henderson methods. Matrix mean square error comparisons are calculated. We also demonstrate that under suitable conditions, the resulting estimator of β is asymptotically normal. The situation with an unknown measurement error covariance matrix is handled. A Monte Carlo simulation study, together with an earthquake data example, is compiled to evaluate the effectiveness of the proposed approach at the end of the paper.

Microbiome variations induced by delta9-tetrahydrocannabinol predict weight reduction in obese mice

IntroductionObesity and high-fat diets induce consistent alterations in gut microbiota composition. Observations from epidemiological reviews and experiments also illustrate weight regulation effects of delta9-tetrahydrocannabinol (THC) with microbiome shifts. Therefore, we investigated the weight-loss potential of THC in obese mice models and to elucidate the contribution of specific gut microbiome changes in THC-induced weight loss.MethodsHigh-fat diet induced obese mice were treated with oral THC supplementation for two weeks and compared with controls. In addition to measuring weight, fecal samples were obtained at various timepoints, sequenced for bacterial 16s rRNA content and analyzed using QIIME2. Alpha and beta diversity were computed followed by linear mixed effects (LME) modeling of bacterial relative abundance relationship to THC treatment and weight change.ResultsIn both male and female mice, the THC group had significantly greater average weight loss than controls (−17.8% vs. −0.22%, p<0.001 and −13.8% vs. +2.9%, p<0.001 respectively). Male mice had 8 bacterial taxonomic features that were both significantly different in relative abundance change over time with THC and correlated with weight change. An LME model using three bacterial features explained 76% of the variance in weight change with 24% of variation explained by fixed effects of feature relative abundance alone. The model also accurately predicted weight change in a second male mouse cohort (R=0.64, R2=0.41, p=<0.001). Female mice had fewer significant predictive features and were difficult to model, but the male-produced 3-feature model still accurately predicted weight change in the females (R=0.66, R2=0.44, p<0.001).ConclusionUsing a stepwise feature selection approach, our results indicate that sex-specific gut microbiome composition changes play some role in THC-induced weight loss. Additionally, we illustrated the concept of microbiome feature-based modeling to predict weight changes.

Acute frailty services: results of a national day of care survey

IntroductionOlder people living with frailty are at high risk of emergency hospital admission and often have complex care needs which may not be adequately met by conventional models of acute care. This has driven the introduction of adaptations to acute care pathways designed to improve outcomes in this patient group. The identification of differences in the organisational approach to frailty may highlight opportunities for quality improvement.MethodsThe Society for Acute Medicine Benchmarking audit is a national service evaluation which uses a single day-of-care methodology to record patient and organisational level data. All acute hospitals in the United Kingdom are eligible to participate. Emergency admissions referred to acute medical services between 00:00 and 23:59 on Thursday 23rd June 2022 were recorded. Information on the structure and operational design of acute frailty services was collected. The use of a validated frailty assessment tool, clinical frailty scale within the first 24 h of admission, assessment by an acute frailty service and clinical outcomes were reported in patients aged 70 year and above. A mixed effect generalised linear model was used to determine factors associated same-day discharge without overnight stay in patients with frailty.ResultsA total of 152 hospitals participated. There was significant heterogeneity in the operational design and staffing model of acute frailty services. The presence of an acute frailty unit was reported in 57 (42.2%) hospitals. The use of validated frailty assessment tools was reported in 117 (90.0%) hospitals, of which 107 (91.5%) used the clinical frailty scale. Patient-level data were recorded for 3604 patients aged 70 years and above. At the patient level, 1626 (45.1%) were assessed using a validated tool during the admission process. Assessment by acute frailty services was associated with an increased likelihood of same-day discharge (adjusted OR 1.55, 95%CI 1.03- 2.39).ConclusionThere is significant variation in the provision of acute frailty services. Frailty-related policies and services are common at the organisational level but implemented inconsistently at the patient level. Older people with frailty or geriatric syndromes assessed by acute frailty services were more likely to be discharged without the need for overnight bed-based admission.

Carbon evolution and mixing effects on groundwater age calculations in fractured basalt, southwestern Idaho, U.S.A.

Using hydrochemical and isotopic compositions of springs and wells, we trace carbon from critical zone carbon dioxide (CO2) into groundwater of the semi-arid Reynolds Creek Experimental Watershed - Critical Zone Observatory, southwestern Idaho, USA. Dissolved inorganic carbon (DIC) concentrations, pH and stable isotope tracers of carbon for DIC (δ13CDIC), are used to show that most groundwater evolves under open system conditions, moving carbon into the groundwater and acting as a carbon sink. However, one sample (−10.94‰ δ13CDIC, 6,350 14C years before present (yrs. BP)) may have evolved under closed system conditions with a higher partial pressure of critical zone CO2 than present-day soils. By characterizing the carbon cycle, we show that (1) carbon evolution is primarily under open-system conditions, (2) shallow groundwater samples are generally less mixed and more recent (10 to 70 3H yrs. BP) than deeper groundwater samples (1,469 to 6,350 14C yrs. BP), and (3) the older portion of the groundwater may be even older than the calculated 14C ages, as indicated by the mixing of age tracers in intermediate wells. Our global conception of the deep critical zone should include carbon cycling of critical zone CO2 in old groundwater. Characterizing the deep critical zone in a semi-arid weathered silicate watershed improves our global understanding of carbon, nutrient and water cycling.

Molecular Recognition in Mechanochemistry: Insights from Solid-State NMR Spectroscopy.

Molecular-recognition events are highly relevant in biology and chemistry. In the present study, we investigated such processes in the solid state under mechanochemical conditions using the formation of racemic phases upon reacting enantiopure entities as example. As test systems, α-(trifluoromethyl)lactic acid (TFLA) and the amino acids serine and alanine were used. The effects of ball-milling and resonant acoustic mixing (RAM) on the formation of racemic phases were probed by using solid-state Nuclear Magnetic Resonance (NMR) spectroscopy. In a mixer mill, a highly efficient and fast racemic phase formation occurred for both TFLA and the two amino acids. RAM led to the racemic phase for TFLA also, and this process was facilitated upon employing pre-milled enantiopure entities. In contrast, under comparable conditions RAM did not result in the formation of racemic phases for serine and alanine.

Associations of exposure to volatile organic compounds with sleep health and potential mediators: analysis of NHANES data

ObjectiveThe effect of environmental pollution on sleep has been widely studied, yet the relationship between exposure to volatile organic compounds (VOCs) and sleep health requires further exploration. We aimed to investigate the single and mixed effect of urinary VOC metabolites on sleep health and identify potential mediators.MethodsData for this cross-sectional study was collected from the National Health and Nutrition Examination Surveys (NHANES) (2005–2006, 2011–2014). A weighted multivariate logistic regression was established to explore the associations of 16 VOCs with four sleep outcomes. Following the selection of important VOCs through the least absolute shrinkage and selection operator (LASSO) regression, principal component analyses (PCA), weight quantile sum (WQS), and Bayesian kernel machine regression (BKMR) analyses were conducted to explore the associations between exposure to single and mixed VOCs and sleep outcomes, as well as identify the most contributing components. A mediation analysis was performed to explore the potential effect of depression scores.ResultsOf the 3,473 participants included in the study, a total of 618 were diagnosed with poor sleep patterns. In logistic regression analyses, 7, 10, 1, and 5 VOCs were significantly positively correlated with poor sleep patterns, abnormal sleep duration, trouble sleeping, and sleep disorders, respectively. The PCA analysis showed that PC1 was substantially linked to a higher risk of poor sleep patterns and its components. The WQS model revealed a positive association between VOC mixture of increased concentrations and poor sleep patterns [OR (95% CI): 1.285 (1.107, 1.493)], abnormal sleep duration [OR (95% CI): 1.154 (1.030, 1.295)], trouble sleeping [OR (95% CI): 1.236 (1.090, 1.403)] and sleep disorders [OR (95% CI): 1.378 (1.118, 1.705)]. The BKMR model found positive associations of the overall VOC exposure with poor sleep patterns, trouble sleeping, and sleep disorders. PCA, WQS, and BKMR models all confirmed the significant role of N-acetyl-S-(N-methylcarbamoyl)-l-cysteine (AMCC) in poor sleep patterns and its components. The depression score was a mediator between the positive VOC mixture index and the four sleep outcomes.ConclusionExposure to single and mixed VOCs negatively affected the sleep health of American population, with AMCC playing a significant role. The depression score was shown to mediate the associations of VOC mixtures with poor sleep patterns and its components.

Ammonia Emissions and Building-Related Mitigation Strategies in Dairy Barns: A Review

In this systematic review, the PRISMA method was applied to examine publications from the last two decades that have investigated the noxious gaseous emissions from dairy barns. The aim was to analyse the outcomes from literature studies estimating the quantities of polluting gases produced in dairy barns, with a specific focus on ammonia (NH3) emissions. Various studies, among those reviewed, have used mixed effects models, mass balance approaches and dispersion methods, revealing significant variability due to different experimental protocols and environmental contexts. Key challenges include the lack of standardised measurement techniques and the limited geographical coverage of research, particularly in climatically extreme regions. This review also explores proposed methods to reduce the associated effects through mitigation strategies. Estimation of NH3 emissions is significantly influenced by the complex interactions between several factors; including animal management practices, such as controlling animal behavioural activities; manure management, like utilising practices for floor manure removal; the type of structure housing the animals, whether it is naturally or mechanically ventilated; and environmental conditions, such as the effects of temperature, wind speed, relative humidity, and ventilation rate on NH3 release in the barn. These influential components have been considered by researchers and targeted mitigation strategies have been identified. Despite growing attention to the issue, gaps in the scientific literature were identified and discussed, particularly regarding the analysis of mitigation strategies and their long-term impacts (i.e., environmental, economic and productivity-wise). The purpose of this review is to help improve research into sustainable agricultural practices and technological innovations, which are fundamental to reducing NH3 emissions and improving air quality in agricultural environments.

The impact of national savings on economic development: a focused study on the ten poorest countries in Sub-Saharan Africa

The purpose of this study is to examine the impact of national savings on economic development, as measured by the Human Development Index (HDI), Inequality-adjusted HDI (iHDI), and Multidimensional Poverty Index (MPI), in ten of the poorest countries in Sub-Saharan Africa. The study employs a sequential Generalized Method of Moments (GMM) analysis to address potential endogeneity issues and account for the dynamic nature of the relationships, covering the period from 2009 to 2019. The findings reveal a complex relationship between national savings and the selected development indicators. While national savings exhibit positive impacts on HDI and iHDI, the results are not consistently statistically significant across all the sequential models. However, the analysis suggests that national savings have a positive influence on reducing multidimensional poverty, as measured by MPI, particularly when effectively channeled into productive investments. The study also highlights the significant positive impact of government expenditure and foreign direct investment (FDI) on human development, underscoring the importance of strategic public investments and foreign capital. The results suggest that while national savings are crucial, their effective utilization is essential for enhancing human development indices. Strategic investments in public goods and foreign capital are also important. The mixed effects of inflation and official development assistance (ODA) emphasize the need for stable economic policies and effective utilization of foreign aid. The modest positive impact of institutional quality suggests that improvements in governance and institutional frameworks can contribute to human development. The findings underscore the need for policies promoting financial inclusion, efficient public expenditure, foreign direct investment, and stable macroeconomic conditions to leverage national savings for economic development. The study’s findings provide valuable insights for policymakers in Sub-Saharan Africa, highlighting the need for comprehensive strategies that leverage national savings, public expenditure, and foreign investment to drive sustainable economic development and poverty reduction.

Joint and Individual Mitochondrial DNA Variation and Cognitive Outcomes in Black and White Older Adults.

Mitochondrial dysfunction manifests in neurodegenerative diseases and other age-associated disorders. In this study, we examined variation in inherited mitochondrial DNA (mtDNA) sequences in Black and White participants from two large aging studies to identify variants related to cognitive function. Participants included self-reported Black and White adults aged ≥ 70 years in the Lifestyle Interventions and Independence for Elders (LIFE; N=1319) and Health Aging and Body Composition (Health ABC; N=7888) studies. Cognitive function was measured by the digit-symbol substitution test (DSST), and the Modified Mini-Mental State Exam (3MSE) at baseline and over follow-up in LIFE (3.6 years) and Health ABC (10 years). We examined joint effects of multiple variants across 16 functional mitochondrial regions with cognitive function using a sequence kernel association test. Based on these results, we prioritized meta-analysis of common variants in Black and White participants using mixed effects models. A Bonferroni adjusted p-value of <0.05 was considered statistically significant. Joint variation in subunits ND1, ND2, and ND5 of Complex I, 12S RNA, and hypervariable region (HVR) were significantly associated with DSST and 3MSE at baseline. In meta-analyses among Black participants, variant m.4216T>C, ND1 was associated with a faster decline in 3MSE, and variant m.462C>T in the HVR was associated with a slower decline in DSST. Variant m.5460G>C, ND2 was associated with slower and m.182C>T in the HVR was associated with faster decline in 3MSE in White participants. Among Black and White adults, oxidative phosphorylation Complex I variants were associated with cognitive function.

Does clinical experience influence the effects of team simulation training in stroke thrombolysis? A prospective cohort study

ObjectivesAfter introducing a team simulation training programme at our hospital, we saw a reduction in door-to-needle times (DNT) for stroke thrombolysis but persisting variability prompting further investigation. Our objective is...

A study of laser-remelted flame-sprayed NiCrBSi/W composite coatings: the influence of thermal diffusivity

AbstractThe article presents research results on the microstructure of laser-remelted NiCrBSi coatings deposited with flame spraying. Two types of coating powders were used. Commercial Metco 15E powder is strengthened with chromium-based carbide and boride phases based on a eutectic form of Ni(Cr) solid solution matrix with borides and Ni silicides. The second powder was also Metco 15E but with the addition of 50 mass% metallic tungsten granules. In both cases, identical parameters of the flame spraying and laser melting processes were used. It was found that introducing tungsten significantly changes the morphology of the coating. This applies to the size of the heat-affected zone, its microstructural nature (grain growth), and the dilution effect. These elements influenced the level of hardness obtained, which was lower in the case of the modified coating. At the same time, however, the modified coating was characterised by a stable microhardness distribution in the cross section, especially in connection with the substrate material. This indicates a strong tendency of tungsten to annihilate the dilution effect and inhibits the decrease in the hardness of the carbide and boride phases associated with the increase in iron content. The factor responsible for the described effects is a significant difference in the thermal diffusivity of the materials used to produce the coatings. This size significantly impacts the scale of the created heat-affected zone and directly affects the mixing effect.

Global scoping review of behavioral interventions to reduce plastic pollution with recommendations for key sectors

AbstractEnd users of single‐use plastics can help minimize their contribution to plastic pollution via mindful purchasing and waste management. These behaviors can be impacted via behavior change interventions in various key sectors of society. This review set out to summarize recent (2015–2023) peer‐reviewed evidence on interventions aimed at changing the plastic consumption, recycling, and/or littering behaviors of individuals across four sectors: business and retail, tourism and leisure, schools and education, and communities. Systematic literature searches were conducted across multiple databases and resulted in the inclusion of 92 intervention studies. Information on intervention strategy and effectiveness was extracted, and the studies were assessed for risk of bias. Intervention descriptions and outcomes were coded into five intervention categories (informational, contextual, prompts, social, and personal strategies) and synthesized qualitatively to inform future practice in an accessible manner. Although nearly half of the reviewed studies were assessed as having moderate‐to‐high risk of bias (e.g., lacked reliability assessment of outcome measures), limiting confidence in the documented findings, the review concludes that different strategies work in different sectors. For example, informational strategies showed mostly promising results in most sectors, but had mixed effectiveness in the education sector, while contextual modifications were effective across sectors.

Cognitive Behavioral Psychotherapy as an Add-on in Comprehensive Outpatient Care of Non-affective Psychoses: A Multicenter Randomized-Controlled Effectiveness Trial in a Naturalistic Setting.

Non-affective psychoses (NAP) are associated with severe consequences with regard to social functioning, physical health, employment, and suicidality. Treatment guidelines recommend cognitive behavioral therapy for psychosis (CBTp) as an effective additional treatment strategy to psychopharmacology. We hypothesized that outpatient CBTp has an add-on effect in individuals with NAP who already receive comprehensive outpatient care (COC) in Germany. In a randomized-controlled effectiveness trial, 6 months of COC + CBTp were compared to COC. The primary outcomes were change of symptom severity as assessed by the Positive and Negative Symptom Scale (pre-/post-treatment and 6-month follow-up). Mixed linear models and effect sizes were used to compare changes across treatment groups. Additionally, the number of readmissions was compared. N = 130 individuals with chronic NAP were recruited (COC + CBTp: n = 64, COC: n = 66). COC + CBTp participants significantly improved more regarding positive symptom severity (estimated mean difference at follow-up: -2.33, 95% CI: -4.04 to -0.61, P = .0083, d = 0.32) and general psychopathology (estimated mean difference at follow-up: -4.55, 95% CI: -7.30 to -1.81, P = .0013, d = 0.44) than the COC group. In both groups, negative symptom severity did not change significantly over time nor did groups differ regarding readmissions. The results underline an add-on benefit of CBTp in chronically ill individuals with NAP. Superiority of CBTp was demonstrated in comparison with high-quality comprehensive care and may also be true in different comprehensive care settings. DRKS00015627.

Comparative pharmacokinetics of a single oral dose of meloxicam in the California sea lion (Zalophus californianus) and Pacific harbor seal (Phoca vitulina richardii).

Pharmacokinetics studies have investigated meloxicam, a non-steroidal anti-inflammatory drug, dosing strategies in a wide variety of non-domestic animals; however, there is no prior study examining well-founded dosing for pinnipeds. To develop dosing protocols, pharmacokinetic information is needed, with an examination of differences between pinniped species. Apparently, healthy California sea lions (Zalophus californianus: CSL; n = 13) and Pacific harbor seals (Phoca vitulina richardii: PHS; n = 17) that had completed rehabilitation were enrolled into a population-based pharmacokinetic study. Each animal was administered a single oral dose of meloxicam at 0.1 mg/kg, and two blood samples were collected from each animal at varying intervals during a 96-h study period. Plasma concentrations of meloxicam were determined by high-pressure liquid chromatography. Data were analyzed with nonlinear mixed effects modeling (Phoenix® NLME™, Certara, St. Louis, MO 63105, USA). The results indicated that in PHS, peak plasma concentration (Cmax) was 0.33 μg/mL with an elimination half-life (Ke t½) of 31.53 h. In CSL, Cmax was 0.17 μg/mL with Ke t½ of 32.71 h. All animals enrolled completed the study without outward adverse clinical signs. The elimination half-life was longer than previously recommended dosing intervals for pinnipeds; however, we cannot speculate in the optimum clinical dose from these results.

Fabrication and Characterization of Biomedical Ti-Mg Composites via Spark Plasma Sintering

The fabrication of Ti-Mg composite biomaterials was investigated using spark plasma sintering (SPS) with varying Mg contents and sintering pressures. The effects of powder mixing, Mg addition, and sintering pressure on the microstructure and mechanical properties of the composite materials were systematically analyzed. Uniform dispersion of Mg within the Ti matrix was achieved, confirming the efficacy of ethanol-assisted ball milling for consistent mixing. The Young’s modulus of the composite materials exhibited a linear decrease with increasing Mg content, with Ti-30vol%Mg and Ti-50vol%Mg demonstrating reduced modulus values compared to pure Ti. Based on density measurements, compression tests, and Young’s modulus results, it was determined that the sinterability of Ti-30vol%Mg saturates at a sintering pressure of approximately 50 MPa. Moreover, our immersion tests in physiological saline underscore the profound significance of our findings. Ti-30vol%Mg maintained compressive strength above that of cortical bone for 6-to-10 days, with mechanical integrity improving under higher sintering pressures. These findings mark a significant leap towards the development of Ti-Mg composite biomaterials with tailored mechanical properties, thereby enhancing biocompatibility and osseointegration for a wide range of biomedical applications.

Structural investigation and physical properties of RO-ZnO-Li2B4O7-K2B4O7 (RO= SrO and BaO) glasses

Glass samples 10RO-30ZnO-xLi2B4O7-(60-x) K2B4O7 (RO=SrO and BaO) with alkali tetra borates varying from 0 to 60 mol% were produced by traditional quenching procedure. Peak free broad X-ray diffraction patterns established the amorphous feature of glass samples. FTIR and Raman spectroscopic analysis had shown existence of BO3 and BO4 structural groups along with other borate units. The BO3 ⇔ BO4 conversion rate was not much affected with variation in one of the alkali-tetraborates. EPR spectra of copper doped glasses confirmed the ground state of Cu2+ ions as 2B1g. Physical and optical properties namely density, molar volume, refractive index, molar refractivity, optical band gap and Urbach energy values were found to be composition dependent. The inflections observed in density, and other optical properties around equal mol% of alkali oxides in the glass system were attributed to structural modifications and mixed alkali effect. These results exposed the structural variations caused due to competitiveness between the two different alkali and alkaline oxides in occupying the geometrical positions of the borate glass network.