Applicability of Construction and Demolition Waste in Geopolymers – A Screening Test

In this study, the applicability of construction and demolition waste (C&DW) in geopolymerization technology was investigated. The C&DW components, concrete and solid bricks, were collected from demolition sites in Belgrade, Republic of Serbia. The concrete sample came from a demolished fifty-year-old construction road, while the remains of solid bricks originated from a 1930s building. Prior to mechanical testing, the C&DW components were characterized by XRD analysis for their mineralogical composition. The results showed that the concrete waste consisted mainly of quartz (SiO2) and calcite (CaCO3), while the brick waste sample contained anorthite from the feldspar group (CaAl2Si2O8), wollastonite (Ca0.957Fe0.043O3Si) and mullite (Al2.4O4.8SiO6). The mechanical properties were examined using the screening method on three geopolymer mixtures, one of each mixture of concrete and brick powders and a mixture of both C&DW components. According to the standard SRPS EN 12390-3:2010 for cubic samples, the geopolymer samples were prepared with alkaline activators for testing the compressive strength as the dominant parameter in the mortar and concrete evaluation. The compressive strength values increased in the range of 2.4 MPa for concrete, 10.2 MPa for brick, and 10.8 MPa for the mixed geopolymer sample. The low compressive strength result of the concrete sample was the consequence of the mineral composition, i.e., the absence of aluminosilicate. However, the brick and the sample with a combination of both types of waste showed moderately satisfactory compressive strength, which could be the starting point for further investigations

A kinetic study of the thermal decomposition process of potassium metabisulfite: Estimation of distributed reactivity model

The thermal decomposition kinetics of potassium metabisulfite was studied by thermogravimetric (TG) and differential thermogravimetric (DTG) techniques using non-isothermal experiments. The apparent activation energy (E-a) is determined using the differential (Friedman) isoconversional method. The results of the Friedmans isoconversional analysis of the TG data suggests that the investigated decomposition process follows a single-step reaction and the observed apparent activation energy was determined as 122.4 +/- 2.1 kJ mol(-1). A kinetic rate equation was derived for the decomposition process of potassium metabisulfite with contracting area model, f(alpha) = 2(1-alpha)(1/2), which is established using the Maleks kinetic procedure. The value of pre-exponential factor (A) is also evaluated and was found to be A = 1.37 x 10(12) min(-1). By applying the Miuras procedure the distributed reactivity model (DRM) for investigated decomposition process was established. From the dependence alpha versus E-a, the experimental distribution curve of apparent activation energies, f(E-a), was estimated. By applying the non-linear least-squares analysis, it was found that the Gaussian distribution model (with distribution parameters E-0 = 121.3 kJ mol(-1) and sigma = 1.5 kJ mol(-1)) represents the best reactivity model for describing the investigated process. Using the Miuras method, the A values were estimated at five different heating rates and the average A values are plotted against E-a. The linear relationship between the A and E-a values was established (compensation effect). Also, it was concluded that the E-a values calculated by the Friedmans method and estimated distribution curve, f(E-a), are correct even in the case when the investigated decomposition process occurs through the single-step reaction mechanism. (C) 2008 Elsevier Ltd. All rights reserved

Pragmatic study of efficiency of controlled-release carbamazepine (TEGRETOL CR 400) in the treatment of patients with partial seizures

In patients with partial seizures controlled-release vs. conventional carbamazepine had better efficiency, based on an excellent tolerance favorable daily dosage and superior compliance

Concussive convulsions as differential diagnosis of posttraumatic epilepsy

Concussive convulsions are motor manifestations in acute head injury. This clinical phenomenon should be distin- guished from epileptic seizures. We present two young men with motor and convulsive manifestations in acute head injury. Patient 1. A18-year old basketball player felt on the parquet during a game. Initially he was struck on the right shoulder which caused brief and vigorous twitch of the head towards the ground and additional temporal impact. At the moment of impact he lost consciousness and developed tonic leg and arm posturing with both clenched fists. His legs were extended during next 20 seconds. Thereafter he was still and his loss of consciousness lasted 3 minutes. Patient 2. A 26-year old man felt on the wooden ground from a 4 m high ferry. He got head impact and lost consciousness. In a few seconds he had tonic/clonic convulsions for the next 10-15 seconds. Ten minutes later he awaked. Results of subsequent neurological examination, electroencephalography and cerebral magnetic resonance imaging studies were normal in both patients. They returned to their occupations after four weeks without problems for a further one year. Conclusion. Described motor manifestations present concussive convulsions. These clinical features are due to transient functional decerebration and corticomedullary dissociation during cerebral concussion. Concussive convulsions are a non-epileptic phenomenon, they are not associated with structural brain injury and have good prognosis. Antiepileptic treatment is not indicated

The first film presentation of REM sleep behavior disorder precedes its scientific debut by 35 years

The perplexing and tantalizing disease of rapid eye movement (REM) sleep behavior disorder (RBD) is characterized by peculiar, potentially dangerous behavior during REM sleep. It was described both in animals and humans. RBD in mammals was first described by Jouvet and Delorme in 1965, based on an experimental model induced by lesion in pontine region of cats [1]. In 1972, Passouant et al. described sleep with eye movements and persistent tonic muscle activity induced by tricyclic antidepressant medication [2], and Tachibana et al., in 1975, the preservation of muscle tone during REM sleep in the acute psychosis induced by alcohol and meprobamate abuse [3]. However, the first formal description of RBD in humans as new parasomnia was made by Schenck et al in 1986 [4-7]. Subsequently, in 1990, the International Classification of Sleep Disorders definitely recognized RBD as new parasomnia [8]. To our knowledge, arts and literature do not mention RBD. Except for the quotation, made by Schenck et al [6] in 2002, of Don Quixote de la Mancha whose behavior in sleep strongly suggested that Miguel de Servantes actually described RBD, no other artistic work has portrayed this disorder. Only recently we become aware of the cinematic presentation of RBD which by decades precedes the first scientific description. The first presentation of RBD on film was made prior to the era of advanced electroencephalography and polysomnography, and even before the discovery of REM sleep by Aserinsky and Kleitman in 1953. [9]. The artistic and intuitive presentation of RBD was produced in Technicolor in a famous film "Cinderella" created by Walt Disney in 1950, some 35 years prior to its original publication in the journal "Sleep" [2]. Since there is an earlier version of the film initially produced in 1920, presumably containing this similar scene, we can only speculate that the first cinematic presentation of RBD might precede its scientific debut by 65 years. In a scene in a barn, clumsy and goofy dog Bruno is, as dogs usually do, lying on a mat deeply asleep and obviously dreaming of his enemy cat Lucifer. This is clearly implied by a preceding scene showing Lucifer being extremely frightened while observing the dreaming dog in action. The cat Lucifer is instantly aware that the dog is chasing him in a dream and is horrified (Pictures 1-3). In a film sequence lasting only 16 seconds, we see Cinderella being aware that Bruno is firmly asleep, apparently having a terrible dream. While lying on the ground with total absence of any muscle atonia, the dog Bruno chases the cat Lucifer in his dream. He is running and barking, and when in his dream he catches Lucifer, he tries to devour the cat. Cinderella tries to wake him up by calling his name twice, first gently and then more vigorously, as she becomes aware of the content of Lucifer’s dream and his intention. The dog is deeply asleep and does not awake in spite of being exposed to sunlight through the opening door of the barn, and called by name by Cinderella (Pictures 4-14). For such a behavior he is reprimanded by Cinderella who definitely recognized the content of his dream (Pictures 15-36). Immediately upon awakening, Bruno shows his good natured temper and amiable character (Pictures 37-40). The film shows that the producer (Walt Disney) and film directors (Wilfred Jackson, Clyde Geronimi and Hamilton Luske) were obviously aware that a dog might enact the content of a dream. It also implies that their observation from day-to-day (better to say night-to-night) life of the dream enactment is not a rare phenomenon, and that it deserves to be shown in the film. These authors were also aware that dogs having RBD were good-natured during wakefulness and that only in dreams they showed unrestrained aggression; while awake, dog Bruno was only an opponent or enemy to the cat Lucifer, but in dreams the animosity grew to aggression. Disney noticed this peculiar kind of sleep behavior and most probably was aware of its frequency and importance, and certainly not knowing it is a disease, he used it to color his cartoon character making it more likable to the observer. Since the film was nominated for Best Score, Best Song and Best Sound, it not only reflected the artistic and observational abilities of the producer, but also his sense of the importance of the phenomenon, awareness of its frequency and presence in animals. The onlooker is tempted to speculate that Disney, while obviously having been aware of such a behavior in animals, might also have knowledge of its presence in humans. Even more, since Disney’s films frequently present different sleep disturbances (e.g., obstructive sleep apnea (OSA) in dwarfs, hypersomnolence in the dwarf Sleepy, or jactatio capitis nocturna in the dwarf Dopey in film "The Snow White"), it seems plausible that he first observed RBD in man, and then artistically transferred it to his cartoon animal characters. Since the whole incident took place during the day, we assume that Bruno, apart from suffering from RBD, had another sleep disorder causing daytime REM intrusions (possibly narcolepsy and probably not OSA, as is frequent in Disney’s films, since there is no excessive daytime sleepiness). The odd thing about RBD is that it may easily, as it probably did for centuries, go as peculiar behavior in sleep – rather than disease. While Lucifer was presented as sober and prudent cat, Bruno was clumsy and forgetful dog. We will refrain from speculating that dog’s clumsy nature could be the consequence of the CNS involvement by neuro-degenerative disease (i.e., synucleinopathy). Although we are aware that, in interpreting this episode we assumed to be at least as imaginative as the cartoon films of Walt Disney are, the fact remains that the artistic film presentation of RBD precedes its scientific description by at least 35 years

Distribution of Natural Radionuclides and 137Cs in Urban Soil Samples from the City of Novi Sad, Serbia-Radiological Risk Assessment

This work presents the natural radioactivity distribution of 21 surface soil samples taken in the city of Novi Sad, Serbia. The analysis for radioactivity was performed using a gas low-level proportional counter for gross alpha and gross beta activity, while the specific activities of radionuclides were determined using HPGe detectors. The gross alpha activity of 20 samples was below the minimum detectable concentration (MDC), while in 1 sample it was 243 Bq kg−1; the gross beta activity ranged from the MDC (11 samples) to 566 Bq kg−1. The gamma spectrometry measurements showed naturally occurring radionuclides 226Ra, 232Th, 40K, and 238U in all investigated samples, with average values (Bq kg−1) of 33.9, 36.7, 513.8, and 34.7, respectively. Natural radionuclide 235U was detected in 18 samples with activity concentrations in the range of 1.3–4.1 Bq kg−1, while in the other 3 samples, the values were below the MDC. The artificial 137Cs radionuclide was detected in 90 percent of the samples, with a maximum value of 21 Bq kg−1, while the other artificial radionuclides were not detected. Based on the obtained concentrations of natural radionuclides, hazard indexes were estimated, and radiological health risk was assessed. The results present the absorbed gamma dose rate in the air, annual effective dose, radium equivalent activity, external hazard index, and lifetime cancer risk