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Objectives/Goals: Electronic health record (EHR)-based recruitment can facilitate participation in clinical trials, but is not a panacea to trial accrual challenges. We conducted a root cause analysis to identify EHR-based accrual barriers and facilitators in a pragmatic randomized trial of metformin for those with prostate cancer and glucose intolerance. Methods/Study Population: We quantitatively analyzed enrollment drop-offs among eligible patients who either did not complete a consent (with analysis of EHR-embedded consent process) or who completed a consent but were not enrolled (with analysis of EHR implementation of a Best Practice Alert). We summarized data from the EHR by eligibility, provider encounters, and alerts, and generated CONSORT diagrams and tables to trace the enrollment pathway. We supplemented quantitative findings with a thematic analysis of semi-structured individual interviews with eligible patients (n = 10) and study providers (n = 4) to identify systematic barriers to recruitment and enrollment of eligible patients. Results/Anticipated Results: CONSORT diagram analysis found that 24% of potentially eligible patients (268 of 1130) had an eligible study encounter but were not enrolled. Additionally, BPAs were not triggering for some eligible patients. Interviews revealed that study providers wanted more detailed information about which study arm their patient would be assigned to, and about next steps after enrollment, especially relating to additional lab tests and follow-up care needed. Patient interviews suggested that patients often did not remember completing the consent process and felt overwhelmed with appointments and information; patients expected providers to actively bring up research opportunities during appointments. Discussion/Significance of Impact: While pragmatic EHR-embedded trials are often characterized as lower-burden, these trials still require active engagement by providers, as well as ongoing attention from both research and informatics teams to ensure that EHR-embedded processes are functioning as designed, and that they are effective in recruiting study participants.
Clastic sedimentary systems and their characteristics are assumed not to have been modified by carbonate bioclastic grains until the Phanerozoic. Here, we show that the presence of carbonate bioclasts produced by disintegrated biomineralizing metazoans modified fine-grained siliciclastic facies in the Late Ediacaran Tamengo Formation, Brazil, ca. 555–542 Ma. The analysis of both polished sections and thin sections shows that sand-sized carbonate bioclasts (< 2 mm) derived from the Ediacaran metazoan Corumbella created diverse sedimentary features later found in the Phanerozoic record, such as bioclastic-rich horizontal and low-angle cross-laminations, erosive pods and lenses, bioclastic syneresis cracks, ripples preserved by bioclastic caps, microbial lamination eroded and filled with bioclasts, and entrapped bioclasts within microbial mats. These sedimentary features would have hardly been recorded in fine siliciclastic facies without the sand-sized bioclasts. Based on these features, together with other sedimentary evidence, Corumbella depositional settings in the Tamengo Fm. are reinterpreted as mid-ramp, subtidal settings. The multi-component organization of the skeleton of Corumbella favoured disarticulation to yield a sand-sized bioclast, so in turn creating a new complexity to shallow marine clastic settings typical of Phanerozoic marine depositional systems.
Migrants and refugees face elevated risks for mental health problems but have limited access to services. This study compared two strategies for training and supervising nonspecialists to deliver a scalable psychological intervention, Group Problem Management Plus (gPM+), in northern Colombia. Adult women who reported elevated psychological distress and functional impairment were randomized to receive gPM+ delivered by nonspecialists who received training and supervision by: 1) a psychologist (specialized technical support); or 2) a nonspecialist who had been trained as a trainer/supervisor (nonspecialized technical support). We examined effectiveness and implementation outcomes using a mixed-methods approach. Thirteen nonspecialists were trained as gPM+ facilitators and three were trained-as-trainers. We enrolled 128 women to participate in gPM+ across the two conditions. Intervention attendance was higher in the specialized technical support condition. The nonspecialized technical support condition demonstrated higher fidelity to gPM+ and lower cost of implementation. Other indicators of effectiveness, adoption and implementation were comparable between the two implementation strategies. These results suggest it is feasible to implement mental health interventions, like gPM+, using lower-resource, community-embedded task sharing models, while maintaining safety and fidelity. Further evidence from fully powered trials is needed to make definitive conclusions about the relative cost of these implementation strategies.
Empathy is an essential skill in the doctor-patient relationship since it contributes to improve aspects of health care and patient satisfaction. Nevertheless, burnout research projects have been developed in recent years.
Objectives
To examine the predictive capacity that empathy has on burnout syndrome in health professionals.
Methods
A non-experimental, cross-sectional design was proposed. The type of study was correlational-descriptive since it was sought out to explore a functional relation through the prognosis of a criterion variable. Sample: 200 (100 female and 100 male).
Results
First, the variance of cognitive and Affective Empathy was dug out in the emotional exhaustation criterion scale. Results accounted for 15% of variability in emotional exhaustation. (Corrected R 2 = .15, F = 17,56, p = 0,00). The best predictor of emotional exhaustation refers to Cognitive Empathy. (B = -.27, p = 0.00). It does not seem that Affective Empathy acts as a predictor variable of Emotional Exhaustation. (Table 1).Table 1
Multiple linear regression analysis considering Emotional Exhaustation as a criterion.
TECA
Corrected R2
F
B
p
Cognitive Empathy
.15
17,5
-.27**
0,00
Affective Empathy
-.14
.13
The predictive capacity of Empathy in relation to Depersonalization was estimated (Corrected R 2 = .20, F = 25,4, p = 0.00). Cognitive and affective empathy were included as predictor variables and MBI as a criterion variable (Table 2). On one hand, the best predictor of Depersonalization is the Cognitive Empathy. On the other hand, regarding Affective Empathy, it does not act as a predictor of Depersonalization.Table 2
Multiple linear regression analysis considering Depersonalization as a criterion.
TECA
Corrected R2
F
B
p
Cognitive Empathy
.20
25,4
-.32**
0,00
Affective Empathy
-.15
.84
Lastly, the predictive capacity of Empathy in relation to Personal Achievement was figured out. (Corrected R 2 = .19, F = 23,4, p = 0.00). Cognitive Empathy is the best predictor for Personal Fulfillment (Table 3).Table 3
Multiple linear regression analysis considering Personal Fullfilment as a criterion.
TECA
Corrected R2
F
β
p
Cognitive Empathy
.20
25,4
.43**
0,00
Affective Empathy
.00
.96
Conclusions
It was noticed that through a linear multiple regression analysis, the variable that best explains Emotional Exhaustation is Cognitive Empathy. Those results are replicated for Depersonalization and Personal Fullfilment.
In the year 2021, there was a notable increase in behaviors associated with anxiety, depression, and stress among school-aged children and adolescents, possibly attributed to the pervasive effects of social isolation and confinement measures.
Objectives
This study conducted a thorough analysis of cases involving students aged 11 to 17 years who exhibited risk factors, anxious and depressive symptoms, and mood disturbances.
Methods
This study focused on students aged 11 to 17 years and employed a comprehensive approach to assess the impact of anxiety, depression, and stress. Cases were meticulously analyzed, and key categories were established to characterize the multifaceted challenges faced by the students. These categories included the availability of family support, utilization of psychopharmacological treatment, engagement in psychological therapies, participation in psychopedagogical interventions, and patterns of school absenteeism.
Results
The analysis revealed a concerning prevalence of anxiety, depression, and stress-related symptoms among the student population. Many students exhibited risk factors that warranted immediate attention, including social isolation, disrupted routines, and uncertainty about the future. Furthermore, a significant portion of students displayed anxious and depressive symptoms, often leading to altered mood and behavioral challenges. In the context of family support, it was apparent that students with robust familial backing tended to cope more effectively with the psychological strain induced by the pandemic. However, a noteworthy number of students lacked adequate family support systems, exacerbating their mental health struggles. Students in need of such interventions benefited significantly from their implementation, demonstrating improved emotional well-being and a reduction in symptom severity. Nonetheless, the accessibility of these services remained a concern, with disparities in access evident among different demographic groups. Psychopedagogical interventions played a pivotal role in addressing issues related to school absenteeism and facilitating a smoother transition to remote learning. Students who engaged in these interventions showed positive progress in terms of school attendance and academic performance.
Conclusions
The findings of this study underscore the urgency of a holistic approach to addressing anxiety, depression, and stress in school-aged children and adolescents. It is imperative that consultations with child and adolescent psychiatry specialists be conducted promptly and in a manner that considers the unique contextual factors influencing each student’s mental health. Moreover, efforts should be directed toward enhancing family support, expanding access to psychopharmacological treatment and psychological therapies, and promoting the implementation of psychopedagogical interventions.
Extremely preterm newborns - EPTN (born ≤28 weeks gestational age) are at increased risk of developing autism spectrum disorders (ASD). Demographic and perinatal risk factors associated with ASD risk in EPTN are understudied.
Objectives
(i) In EPTN and born at full-term healthy controls (HC), to characterize the emergence of ASD traits and autistic symptom load at age 18 months; (ii) in EPTN, to identify the influence of perinatal characteristics such as sex and gestational age on autistic symptom load at corrected-age 18 months.
Methods
Observational, longitudinal, prospective, 18-month follow-up study. We recruited a cohort of n=113 EPTN and n=47 HC (the PremTEA cohort); n=57 EPTN and n=42 HC successfully completed the 18-month follow-up visit. We assessed autistic symptom load & risk at 18 months using the M-CHAT-R/F questionnaire. For all EPTN and HC, we collected demographic and perinatal data. Using GLMs, we assessed, in EPTN, the association between demographic/perinatal variables and 18-month autistic symptom levels.
Results
At 18 months, EPTN children showed higher autistic symptom levels than HC (M-CHAT-R/F score, mean (SD) [range] = 2.21 (3.23) [0-12] in EPTN vs. 0.33 (0.57) [0-2] in HC; d=.873, p=.001. In EPTN, we identified differences by gestational age and sex in autistic symptom levels at 18 months (aR2=0.517, p=.006). In particular, female EPTNs born with lower gestational age showed higher autistic symptom load at age 18 months.
Conclusions
Our findings support the need for early screening of ASD symptomatology in EPTN infants, particularly in higher-risk subgroups, such as female patients born with lower gestational ages.
According to Bisquerra Alzina (2003),competencies are defined as a set of knowledge, capabilities, skills and attitudes, necessary to understand, express and regulate emotional phenomena appropriately and which are fundamental in the teaching profesion since they are closely related to students´performance and mental health.
Objectives
compare socio-emotional skills in two groups of participants: female and male
Methods
A non-experimental,cross-sectional design was proposed for this study. The scope of this research is descriptive, in the sense,that it seeks to establish measures in regard to specific variables. Sample (100 female and 100 male).
Results
Results revealed that the evaluated teachers show average level of socio-emotional competencies, (Table 1).The highest scores were encountered in relation to the optimism competence. It suggests that teachers have the ability to obtain favorable balances from adverse situations presented in their daily lives.Table 1:
Distribution of socio-emotional competency levels in the professionals evaluated
LOW %
MEDIUM %
HIGHT %
EMOTIONAL AWARENESS
19
80
1
SELF EFFICACY
32
66
2
EMOTIONAL REGULATION
17
81
2
EMOTIONAL EXPRESSION
6
85
9
PROSOCIALITY
6
85
9
ASSERTIVENESS
6
82
12
OPTIMISM
0
21
79
EMOTIONAL AUTONOMY
25
71
4
EMPATHY
8
85
7
Findings showed that there exists a statiscally significative difference (P=0,000) in the empathy and self-efficacy dimensions. Women obtained higher scores in these two abilities in regard to men. (Table 2). No differences were observed in the rest of the competences evaluated.Table 2:
Differences according to men and women
FEMALE
MALE
SELF EFFICACY
1,78
1,61
EMPATHY
2,02
1,96
Conclusions
Although teachers´s socio-emotional competences were classified in medium levels, it is necessary to implement an intervention design that allows to streghten those dimensions since they could improve not only the relationships with their students but also teachers´ mental health.
The use of long-acting treatments is a common clinical practice in psychiatry. No disease insight and the risk of treatment discontinuation in a significant portion of our patients, increase the demand for psychiatric emergency and hospital admissions. Treatment adherence must be facilitated, taking into account possible side effects and patient´s subjective satisfaction.
Objectives
-Evaluate the type of long-acting intramuscular treatment in selected patients. -Evaluate the differences in treatment satisfaction between different types of long-acting intramuscular treatments as well as frequency of psychiatric emergency and hospital admissions in the last year.
Methods
We select patients with different severe mental disorders who stay in a Medium Stay Unit, Sociosanitary Community Residence, Supervise house and Residence for the elderly in Albacete (Spain); all of them, with intramuscular neuroleptic treatment (zuclopenthixol dihydrochloride, aripiprazole long acting, palmitate paliperidone monthly, 3-monthly and 6-monthly) at least 1 year.
We evaluate their sociodemographic characteristics, the satisfaction questionnaire with the treatment (TSQM-9) and the rate of psychiatric emergencies and admissions after current intramuscular treatment in last year.
Results
We have selected 57 patients with an average age of 45.86. 78.94% with a diagnosis of schizophrenia, 12.28% with schizoaffective disorder, 5.26% bipolar disorder and 3.5% unspecified psychotic disorder.
We can see in the graphics below that the longer duration of the intramuscular treatment, the greater satisfaction in all the items of the TSQM-9 questionnaire.
31% of the patients with zuclopenthixol dihydrochloride treatment, have gone to psychiatric emergencies and 28% of psychiatric admissions in the last year.18% of the patients with aripiprazole long acting, 17% with paliperidone palmitate long acting-monthly and 12% de 3-monthly have gone to psychiatric emergencies and 15%, 12% and 12% needed psychiatric admissions respectively. Patients with palmitate long acting-monthly have not emergencies or psychiatric admissions in the last year.
Image:
Image 2:
Image 3:
Conclusions
- The longer long acting of the intramuscular treatments, the better patient satisfaction.
- With the longer duration treatment (Palmitate paliperidone LD 6 month), we have lower psychiatric emergencies and hospital admissions.
The American Academy of Pediatrics reports an incidence of 1 in every 54 children (Council on Children with Disabilities, 2021). The unique circumstances surrounding children born in 2020, who have experienced the COVID-19 pandemic since birth, present a distinct set of challenges for their neurodevelopmental well-being. The pandemic has led to reduced opportunities for learning and social interaction, masking mandates, decreased social support for research, and the potential misattribution of Autism Spectrum Disorders ASD symptoms to the effects of social isolation.
Objectives
This study aims to develop such a program for children born during the COVID-19 pandemic (2020-2022).
Methods
All children born in March 2020 were included in the study. The initial assessment involved administering the ASQ-3 to evaluate their development across the specified domains. Diagnostic Evaluation: Among the population, 6% (4 children) displayed concerning signs on the ASQ-3, warranting further diagnostic evaluation by specialized health professionals for possible ASD.
Results
Early Intervention and School Monitoring: Of the remaining 72% (46 children), who did not require diagnostic evaluation, intervention guidelines were provided, both within the school environment and at home. These children were reevaluated after a three-month period. Follow-up in the School Environment: Those children who underwent reevaluation were categorized into three groups: Nine children fell into the “gray” category on the ASQ-3 and were subsequently referred for diagnostic evaluation. Thirty-seven children progressed to the “white” category on the ASQ-3 after receiving intervention guidelines in both school and home settings. The findings of this research underscore the potential impact of the COVID-19 pandemic on the neurodevelopment of children born in 2020. 6% of the evaluated population were referred for diagnostic evaluation due to signs of ASD, suggesting a potential association between the pandemic and an increased risk of ASD within this cohort.72% of children who received intervention guidelines demonstrated significant improvements in their neurodevelopment, highlighting the critical role of early intervention and school-based monitoring
Conclusions
Implementing support strategies within educational settings was linked to positive developments in neurodevelopmental outcomes. Consequently, school-based neurodevelopmental monitoring, complemented by cohesive curricular guidelines, emerges as a beneficial approach for enhancing child development outcomes. The ASQ-3, as a structured instrument, proves invaluable in facilitating neurodevelopmental surveillance within educational settings, particularly in contexts with high demand and limited access to specialized care.
Generalized anxiety disorder (GAD) is one of the most common mental disorders in adults. Psychotherapies are among the most recommended treatment choices for GAD, but which should be considered as first-line treatment still needs to be clarified.
Objectives
To examine the most effective and accepted psychotherapy for GAD both in the short and long-term, via a network meta-analysis.
Methods
We searched MEDLINE, Embase, PsycINFO, and the Cochrane Register of Controlled Trials – CENTRAL, from database inception to January 1st, 2023, to find randomized controlled trials (RCTs) of psychotherapies for GAD. Eight psychotherapies (behaviour therapy, cognitive-behaviour therapy, cognitive restructuring, psychoeducation, psychodynamic therapy, relaxation therapy, supportive psychotherapy, and third-wave CBTs) were compared with each other and two control conditions (treatment as usual, waiting list). We followed Cochrane standards when extracting data and assessing data quality and used PRISMA guidelines for the reporting. We conducted random-effects model pairwise and network meta-analyses. We assessed risk of bias of individual studies through the second version of the Cochrane’s Risk of Bias tool and used the Confidence in Network Meta-Analysis (CINeMA) to rate certainty of evidence for meta-analytical results. Severity of GAD symptoms and acceptability of the psychotherapies were our outcomes of interest.
Results
We analysed data from 66 RCTs. Effect size estimates on data from 5,597 participants suggest third wave cognitive-behavioural therapies (standardized mean differences [SMDs] =-0.78; 95%CI=-1.19 to -0.37; certainty=moderate), cognitive-behavioural therapy (CBT) (SMD=-0.68; 95%CI=-1.05 to -0.32 certainty=moderate), and relaxation therapy (SMD=-0.54; 95%CI=-1.04 to -0.05; certainty=low) reduced generalized anxiety symptoms more than treatment as usual (TAU). Relative risks for all-cause discontinuation signalled no differences compared with TAU for all psychotherapies. When excluding studies at high risk of bias, relaxation therapy lost its superiority over TAU. When considering anxiety severity at three to twelve months after completion of the intervention only CBT remained significantly more efficacious than TAU (SMD=-0.58; 95%CI=-0.93 to -0.23).
Image:
Conclusions
Given the evidence for both acute and long-term efficacy, CBT may represent the reasonable first-line psychological treatment for GAD. Third-wave CBT and relaxation therapy have short-term efficacy and may also be offered. Results from this investigation should inform patients, clinicians, and guidelines. This project is funded by the European Union’s HORIZON EUROPE research programme under grant agreement No 101061648.
To simulate the impact on calcium intake – effectiveness and safety – of fortifying wheat flour with 200, 400 and 500 mg of calcium per 100 g of flour.
Design:
Secondary analysis of cross-sectional data collected through repeated 24 h dietary recalls using the Iowa State University Intake Modelling, Assessment and Planning Program.
Setting:
Urban cities in the National Health and Nutrition Survey of Argentina (ENNyS 2018–2019).
Participants:
21 358 participants, including children, adolescents and adults.
Results:
Most individuals in all age groups reported consuming wheat flour. The prevalence of low calcium intake was above 80 % in individuals older than 9 years. Simulating the fortification of 500 mg of calcium per 100 g of wheat flour showed that the prevalence of low calcium intake could be reduced by more than 40 percentage points in girls and women aged 19 to less than 51 years and boys and men aged 4 to less than 71 years, while it remained above 65 % in older ages. The percentages above the upper intake level remained below 1·5 % in all age groups.
Conclusions:
Calcium flour fortification could be further explored to improve calcium intake. Subnational simulations could be performed to identify groups that might not be reached by this strategy that could be explored in Argentina. This analysis could be used to advocate for a strategy to fortify wheat flour.
Plant growth requires the integration of internal and external cues, perceived and transduced into a developmental programme of cell division, elongation and wall thickening. Mechanical forces contribute to this regulation, and thigmomorphogenesis typically includes reducing stem height, increasing stem diameter, and a canonical transcriptomic response. We present data on a bZIP transcription factor involved in this process in grasses. Brachypodium distachyon SECONDARY WALL INTERACTING bZIP (SWIZ) protein translocated into the nucleus following mechanostimulation. Classical touch-responsive genes were upregulated in B. distachyon roots following touch, including significant induction of the glycoside hydrolase 17 family, which may be unique to grass thigmomorphogenesis. SWIZ protein binding to an E-box variant in exons and introns was associated with immediate activation followed by repression of gene expression. SWIZ overexpression resulted in plants with reduced stem and root elongation. These data further define plant touch-responsive transcriptomics and physiology, offering insights into grass mechanotranduction dynamics.
Edited by
William J. Brady, University of Virginia,Mark R. Sochor, University of Virginia,Paul E. Pepe, Metropolitan EMS Medical Directors Global Alliance, Florida,John C. Maino II, Michigan International Speedway, Brooklyn,K. Sophia Dyer, Boston University Chobanian and Avedisian School of Medicine, Massachusetts
Community events can have several definitions depending on context. For legal definitions, the determination of a community event might have specific use of space, public or private for gathering, either public or nonprofit. This might change based on the local regulatory definitions. Other broader consideration of a community event is an event with a gathering of people, sometime defined as more than fifty for a multitude of purposes. Concert, protest, festival, graduations, street-block parties, celebrations (such as religious, weddings, marking a holiday), for fund raising, or unplanned events such as social protest (for example the many protests and marches after the death of George Floyd or in support of Ukraine after the Russian invasion). Community events have benefits to the community, social connection, support for groups and individuals for whom the event was planned and financial benefit for community-based both municipal and private business. More longitudinal benefit to the community can come from publicity about the event and the community for tourism events outside of the confines of the event days.
The aim of this paper is to study supersoluble skew braces, a class of skew braces that encompasses all finite skew braces of square-free order. It turns out that finite supersoluble skew braces have Sylow towers and that in an arbitrary supersoluble skew brace B many relevant skew brace-theoretical properties are easier to identify: For example, a centrally nilpotent ideal of B is B-centrally nilpotent, a fact that simplifies the computational search for the Fitting ideal; also, B has finite multipermutational level if and only if $(B,+)$ is nilpotent.
Given a finite presentation of the structure skew brace $G(X,r)$ associated with a finite nondegenerate solution of the Yang–Baxter equation (YBE), there is an algorithm that decides if $G(X,r)$ is supersoluble or not. Moreover, supersoluble skew braces are examples of almost polycyclic skew braces, so they give rise to solutions of the YBE on which one can algorithmically work on.
PEPAdb (Prehistoric Europe's Personal Adornment Database) is a long-term, open-ended project that aims to improve access to archaeological data online. Its website (https://pepadb.us.es) publishes and analyses datasets about prehistoric personal adornment, drawing on the results of various research projects and bibliographic references.
Palygorskite fibers growing along fault planes in the outcrops of a large fault zone in SE Spain (Carboneras Fault Zone: CFZ; Serrata de Níjar) were studied by X-ray diffraction, scanning electron microscopy-energy dispersive X-ray analysis, and transmission electron microscopy-analytical electron microscopy. The structural formulae, calculated per half unit-cell, is: Si7.95Al0.05O20(Al1.93Fe0.08Mg1.92) (OH)2(OH2)4Na0.09K0.01Ca0.034(H2O). The samples have minor tetrahedral substitutions, with Mg/Al ratios close to one, and contain very small amounts of Fe3+. The number of octahedral cations per half unit-cell is 3.93. The fault-hosted palygorskite shows macroscopic ductile features including incipient foliation. Based on field and laboratory observations, as well as on regional geological evidence indicating the existence of widespread hydrothermal processes along the Serrata de Níjar and surrounding areas, we suggest that palygorskite may have formed during ongoing deformation in the CFZ, as a precipitate from Mg-rich hydrothermal fluids.
A geological, mineralogical, and geochemical characterization of the Tamame de Sayago (Zamora, Spain) deposit was carried out with the aim of knowing the conditions that facilitated the genesis in the same deposit of kaolinite and smectites. The alteration processes affecting a Variscan granite were deduced throughout the study of a very wide group of representative samples by X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical analyses of major, minor, and trace elements, as well as δ18O, δ34S stable isotope and K/Ar dating analyses. In addition, 2D and 2.5D graphs of the kaolinite and smectite isoconcentrations were obtained from core data. According to the color and texture, two different clayey rock types were identified and named as homogeneous alteration zones (ZAHO) and heterogeneous alteration zones (ZAHE). The ZAHO are regoliths in which the granite texture is preserved, and the feldspars are almost completely kaolinized. In the ZAHE, the original texture of the granitic rock is lost, and the main clay mineral is smectite. The mineralogical composition is similar, with kaolinite, smectite, mica, quartz, scarce feldspar, and occasionally natroalunite and APS (aluminum-phosphate-sulphate); however, the mineral concentration varies considerably because ZAHO are rich in kaolin areas whereas ZAHE are bentonitic areas. Both rock types contain numerous veins and nodules. The weathering of the Paleozoic granite alongside the absence of sedimentation during the Mesozoic led to the formation of kaolinite that is preserved in ZAHO materials. Nonetheless, during the Cretaceous–Tertiary transit, the conditions of tectonic stability varied. Late Variscan faults reactivated which allowed the percolation of Mg- and Ca-rich hydrothermal fluids through the already kaolinized granite, increasing the alteration of the primary silicates and leading to the formation of smectites in ZAHE materials. The amount of smectites is greater closer to the faults. The stable isotopes indicate the meteoric nature of the low-temperature hydrothermal fluids. The K/Ar data obtained from the natroalunite of veins indicate that those hydrothermal fluids circulated in different pulses from 66.4 ± 1.7 to 58.8 ± 1.5 Ma, as a minimum. Those ages are coincident with the first formation stages of the Duero Basin.
Many studies of the chemical composition of sepiolite and palygorskite have been carried out using analytical electron microscopy (AEM). According to the literature, a compositional gap exists between sepiolites and palygorskites, but the results presented here show that they may all be intermediate compositions between two extremes. The results of >1000 AEM analyses and structural formulae have been obtained for the samples studied (22 samples of sepiolite and 21 samples of palygorskite) and indicate that no compositional gap exists between sepiolite and palygorskite. Sepiolite occupies the most magnesic and trioctahedral extreme and palygorskite the most aluminic-magnesic and dioctahedral extreme. Sepiolite and palygorskite with intermediate compositions exist between the two pure extremes: (1) sepiolite with a small proportion of octahedral substitution; (2) palygorskite with a very wide range of substitution (the pure dioctahedral extreme is unusual); and (3) intermediate forms, Al-sepiolite and Mg-palygorskite with similar or the same chemical composition. The chemical compositions of the intermediate forms can be so similar that a certain degree of polymorphism exists between Al-sepiolite and Mg-palygorskite.
The Allou Kagne (Senegal) deposit consists of different proportions of palygorskite and sepiolite, and these are associated with small quantities of quartz and X-ray amorphous silica as impurities. No pure palygorskite or sepiolite has been recognized by X-ray diffraction. Textural and microtextural features indicate that fibrous clay minerals of the Allou Kagne deposit were formed by direct precipitation from solution. Crystal-chemistry data obtained by analytical/transmission electron microscopy (AEM/TEM) analyses of isolated fibers show that the chemical composition of the particles varies over a wide range, from a composition corresponding to palygorskite to a composition intermediate between that of sepiolite and palygorskite, but particles with a composition corresponding to sepiolite have not been found. Taking into account the results from selected area electron diffraction and AEM-TEM, fibers of pure palygorskite and sepiolite have been found but it cannot be confirmed that all of the particles analyzed correspond to pure palygorskite or pure sepiolite because both minerals can occur together at the crystallite scale. In addition, the presence of Mg-rich palygorskite and very Al-rich sepiolite can be deduced.
It is infrequent in nature that palygorskite and sepiolite appear together because the conditions for simultaneous formation of the two minerals are very restricted. The chemical composition of the solution controls the formation of the Allou Kagne sepiolite and palygorskite. The wide compositional variation appears as a consequence of temporary variations of the chemical composition of the solution.
Palygorskite in Miocene mudstones, palustrine limestones and calcretes from the Esquivias locality (Madrid Basin, Spain) has been analyzed by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, transmission electron microscopy and analytical electron microscopy to determine its characteristics and chemical composition. Other palygorskites from the literature are used as references. The mean structural formula obtained from the analysis of isolated particles is (Si7.87Al0.13)O20()(OH)2(OH2)4(Ca0.02K0.05Na0.08). This palygorskite has the largest Mg content reported in the literature, and it seems that, chemically, it fills the ‘compositional gap’ existing between sepiolite and palygorskite. Infrared spectroscopy reveals the absence of trioctahedral Mg and therefore the possibility of the existence of magnesic clusters in the ribbons is discounted. An homogeneous distribution of the octahedral cations (Al, Fe3+ and Mg) along the ribbons is proposed.