Burnt clays provide a vital source of information about the archaeomagnetic field but their magnetic properties, and the dependency of these on thermal history, are diverse, complex and poorly ...understood. Here, we attempt to shed light on this problem through the investigation of artificial clay samples prepared from three different clay types repeatedly heated in known magnetic field to two different temperatures (400 and 700 °C). Combined rock-magnetic and X-ray analyses were carried out to obtain information about the mineralogical content and magnetic properties of the diverse raw and heated clays, and also their evolution during the course of multiple heating/cooling treatments. The magnetic behaviour of the three clay types evolved significantly during the course of being repeatedly heated to both 400 and 700 °C. Phyllosilicates containing iron-substitutions in their matrix apparently played an important role in supplying iron- oxides during the heatings and the iron oxides themselves underwent progressive oxidation. The samples heated to the higher temperature exhibited more ideal magnetic behaviour but even those heated only to 400 °C achieved magnetic stabilization after multiple heatings. After 10 reheating treatments, samples heated to both peak temperatures yielded reliable palaeointensity results and a grand mean intensity value F
a = 48.57 ± 1.19 μT which differs by less than 2 μT (or about 3 per cent) from the known intensity of the inducing field. The results confirm that the thermoremanent magnetization produced as a result of multiple heatings even to moderate temperature in the antiquity can give reliable palaeointensity determination. They also highlight that materials from repeatedly used baked clay structures (kilns, hearths, etc.) may be far more appropriate for archaeointensity study than singly baked clay structures (destruction layers, floor plasters, etc.).
The identification of epsilon iron oxide (ɛ‐Fe2O3) as the low Curie temperature high coercivity stable phase (HCSLT) carrying the remanence in heated archeological samples has been achieved in ...samples from two archeological sites that exhibited the clearest evidence of the presence of the HCSLT. This uncommon iron oxide has been detected by Confocal Raman Spectroscopy (CRS) and characterized by rock magnetic measurements. Large numbers of ɛ‐Fe2O3 microaggregates (in CO) or isolated clusters (in HEL) could be recognized, distributed over the whole sample, and embedded within the ceramic matrix, along with hematite and pseudobrookite and with minor amounts of anatase, rutile, and maghemite. Curie temperature estimates of around 170°C for CO and 190°C for HEL are lower than for pure, synthetic ɛ‐Fe2O3 (227°C). This, together with structural differences between the Raman spectra of the archeologically derived and synthetic samples, is likely due to Ti substitution in the ɛ‐Fe2O3 crystal lattice. The γ‐Fe2O3‐ɛ‐Fe2O3‐α‐Fe2O3 transformation series has been recognized in heated archeological samples, which may have implications in terms of their thermal history and in the factors that govern the formation of ɛ‐Fe2O3.
Key Points
ɛ‐Fe2O3, a rare iron oxide polymorph, has been identified in archeological brick and baked clay
It has been found as part of the γ‐Fe2O‐ɛ‐Fe2O3‐α‐Fe2O3 transformation series
CRS and mineral magnetic measurements have proved a powerful combination for identifying complex magnetic mixtures in natural samples
Archaeological baked clay remains provide valuable information about the geomagnetic field in historical past, but determination of the geomagnetic field characteristics, especially intensity, is ...often a difficult task. This study was undertaken to elucidate the reasons for unsuccessful intensity determination experiments obtained from two different Bulgarian archaeological sites (Nessebar – Early Byzantine period and Malenovo – Early Iron Age). With this aim, artificial clay samples were formed in the laboratory and investigated. The clay used for the artificial samples preparation differs according to its initial state. Nessebar clay was baked in the antiquity, but Malenovo clay was raw, taken from the clay deposit near the site. The obtained artificial samples were repeatedly heated eight times in known magnetic field to 700 °C. X-ray diffraction analyses and rock-magnetic experiments were performed to obtain information about the mineralogical content and magnetic properties of the initial and laboratory heated clays. Two different protocols were applied for the intensity determination—Coe version of Thellier and Thellier method and multispecimen parallel differential pTRM protocol. Various combinations of laboratory fields and mutual positions of the directions of laboratory field and carried thermoremanence were used in the performed Coe experiment. The obtained results indicate that the failure of this experiment is probably related to unfavourable grain sizes of the prevailing magnetic carriers combined with the chosen experimental conditions. The multispecimen parallel differential pTRM protocol in its original form gives excellent results for the artificial samples, but failed for the real samples (samples coming from previously studied kilns of Nessebar and Malenovo sites). Obviously the strong dependence of this method on the homogeneity of the used subsamples hinders its implementation in its original form for archaeomaterials. The latter are often heterogeneous due to variable heating conditions in the different parts of the archaeological structures. The study draws attention to the importance of multiple heating for the stabilization of grain size distribution in baked clay materials and the need of elucidation of this question.
This data brief reports the latest updates of archeomagnetic data obtained at the Sofia palaeomagnetic laboratory of the Geophysical Institute, Bulgarian Academy of Sciences. The current data set ...consists of measurements from 284 Bulgarian archeological sites covering the past 8000 years. There are also 54 sites from other European regions, namely, Serbia, Kossovo, Greece, Spain, Switzerland, Finland, and Russian Karelia, as well as five sites from Morocco in North Africa. The update of the archeomagnetic results consisted of a thorough revision of all geomagnetic field measurements as well as dating these measurements that were published in the original papers or in previous compilations. The updated results can be found in GEOMAGIA (http://geomagia.ucsd.edu) or as an Excel spreadsheet at the EarthRef.org Digital Archive (http://earthref.org/cgi‐bin/erda.cgi?n = 946).
Non-invasive ventilation (NIV) is considered a fundamental method in treating patients with various disorders, requiring respiratory support. Often the lack of beds in the intensive care unit (ICU) ...and the concomitant medical conditions, which refer patients as unsuitable for aggressive treatment in the ICU, highlight the need of NIV application in general non-monitored wards and unusual settings – most commonly emergency departments, high-dependency units, pulmonary wards, and even ambulances. Recent studies suggest faster improvement of all physiological variables, reduced intubation rates, postoperative pulmonary complications and hospital mortality with better outcome and quality of life by early well-monitored ward-based NIV compared to standard medical therapy in patients with exacerbation of a chronic obstructive pulmonary disease, after a surgical procedure or acute hypoxemic respiratory failure in hematologic malignancies. NIV is a ceiling of treatment and a comfort measure in many patients with do-not-intubate orders due to terminal illnesses. NIV is beneficial only by proper administration with appropriate monitoring and screening for early NIV failure. Successful NIV application in a ward requires a well-equipped area and adequately trained multidisciplinary team. It could be initiated not only by attending physicians, respiratory technicians, and nurses but also by medical emergency teams. Ward-based NIV is supposed to be more cost-effective than NIV in the ICU, but further investigation is required to establish the safety and efficacy in hospital wards with a low nurse to patient ratio.
The esophageal diverticula are divided into pharyngoesophageal, parabronchial and epiphrenic. They could also be divided into congenital and acquired, true and false, pulsion and traction. Pulsion ...diverticula are usually formed in motor disorders of the esophagus, above the place of hypertension and uncoordinated peristalsis. They are pseudo-diverticula caused by increased intramural pressure, leading to herniation of the mucosa and submucosa through the focal areas of the esophageal wall. We present a 65-year-old woman who underwent left-sided transthoracic diverticulectomy, modified Heller esophagocardiomyotomy, and modified Belsey-Mark IV fundoplication due to a huge epiphrenic esophageal diverticulum.
The widespread occurrence of a novel, high coercivity magnetic phase in well‐heated archeological material is reported. Its properties are defined when it represents the dominant magnetic phase, ...although it is nearly always found as part of a mixture of magnetic phases. They are as follows: very high coercivity (remanence coercivity >600 mT), low unblocking temperatures (≤200°C) and high degree of thermal stability–this last property distinguishing it from goethite. The phase shows striking similarities to magnetic phases produced by thermal decomposition of nontronite (an Fe‐rich clay), where decomposition occurs after prolonged heating in air to high temperatures – conditions suffered by well‐heated archeomagnetic material. Preliminary results of Mössbauer and X‐Ray diffraction spectroscopy suggest that the phase is more likely to be a substituted hematite, rather than Fe‐cristobalite or a variant of ɛ‐Fe2O3.
Surgical interventions for intractable and unamenable for dilatation peptic esophageal strictures could sometimes be difficult and challenging. Esophageal perforation management depends on many ...factors such as underlying esophageal disease, location and cause of perforation, age, overall condition, comorbidities, and time from perforation to presentation. Of great importance for the selection of technique is whether the esophagus is normal and it is worthwhile trying not to remove it or whether it is pathologically changed and it is reasonable to proceed with resection during the initial intervention. We present a patient who has undergone surgery several times in another hospital for perforation of peptic stricture in the distal part of the esophagus and esophageal diversion in its proximal part. Three months later, he was admitted to the Thoracic Surgery Department and resection of the excluded esophagus followed by thoracic duct ligation for chylothorax was performed. After another three months, retrosternal colon replacement and subsequent removal of the gastrostomy were performed.
The main treatment in nearly every case of thyroid cancer is surgery. The exception often refers to anaplastic carcinoma because this cancer is already widespread at the time of diagnosis. Most of ...the cases are treated with thyroidectomy, but small tumors that spread inside the thyroid gland might be treated by lobectomy. Intrathoracic goiter accounts for 5.8% of all mediastinal masses. On the other hand, the incidence of thyroid malignancy in cervico-mediastinal thyroid masses is 7,7%. In such cases, total thyroidectomy with en block removal of the mediastinal portion of the gland is the treatment of choice. We present a case of a 34-year-old woman with cervico-mediastinal malignant goiter.
Gastroesophageal junction adenocarcinoma is a rare type of cancer of the esophagus. It is usually diagnosed in advanced stages and much less frequently in the earlier stage, where surgical treatment ...is essential. Surgical treatment is also essential in kidney cancer. The occurrence of synchronous malignancies with an esophageal malignancy is a well-described phenomenon with an incidence ranging from 3.6 to 27.1%. To the best of our knowledge, only 11 cases of synchronous esophageal and renal cell carcinoma (RCC) have been previously described. We present a patient operated simultaneously for cancer of the gastroesophageal junction with synchronous renal cell carcinoma. The finding in the kidney was accidentally discovered by the routine CT scan on the occasion of the relatively early carcinoma of the gastroesophageal junction detected by upper endoscopy. The patient was admitted to the Thoracic Surgery Department, where Ivor-Lewis gastroesophagoplasty and right nephrectomy simultaneously were performed. The patient was followed for 5 years without evidence of disease progression.
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