Chimney stack repair at the thermal power station in Sisak

Opisana je sanacija dimnjaka Termoelektrane Sisak visokog 140 m. Dani su osnovni tehnički podaci o dimnjaku i prikazano je njegovo stanje prije sanacije. Podrobno je opisano projektiranje i izvedba sanacije koja je obuhvaćala unutarnji i vanjski dio dimnjaka. Radilo se uglavnom o izmjenama ozida i zatvaranju pukotina prije njegove izvedbe. U zaključku se daju preporuke, temeljene na sanacijom stečenim iskustvima, o mjerama koje treba poduzeti u cilju trajnije upotrebe dimnjaka.Structural repair of the 140 m high chimney stack at the thermal power station in Sisak is described. Basic technical information about the chimney stack is presented and its condition prior to remedial activities is described. A detailed account is given about the design and realization of repair work, which included remedy of internal and external portions of the chimney stack. The work mainly consisted in the replacement of the walling and in closing cracks prior to the principal work. Recommendations based on experience gained on this repair project, including measures needed to extend service life of chimney stacks, are given in the final part of the paper

Thin-walled laminated structural elements

Opisuje se oblikovanje konstrukcija sastavljenih od tankostijenih lamela koje tvore nosive prostorne elemente. Prikazan je postupak spajanja niza tipskih elemenata s raznim zakrivljenostima u nosive konstrukcije koje mogu služiti u razne svrhe kao što su stijene za zaštitu prometnica od vjetra, krovne konstrukcije i drugo. Prikazana je primjena lamelnih elemenata za izradu saćastih konstrukcija na objektima zaštite prometnica od vjetra i na cilindričnoj krovnoj konstrukciji.The design of structures composed of thin-walled lamellas formed in such a way to serve as load-bearing space elements is described. The author presents the procedure for linking a number of differently curved typical elements in order to form load bearing structures that may be used for various purposes, e.g. as screens for road protection against wind action, as roof structures, etc. The use of laminated elements for the construction of cellular wind screens applied on roads, as well as for cylindrical roof structures, is presented

Does behavioral response to novelty influence paw withdrawal latencies in repeated Hargreaves test?

Background and Purpose: Only recently, we have reported that single retesting session significantly decreases rat paw withdrawal latencies (PWL) in Hargreaves tests.We wondered, whether decrease in PWL values obtained during reexposure toHargreaves testmight be associated with reaction to the new environment. Therefore, we investigated PWL together with the open field behavior in an enclosure of the Hargreaves test device during the period of 3 subsequent days. Materials and Methods: Ten male Wistar rats were tested once a day. Each rat was first exposed to the open field behavior test for five minutes and then to the Hargreaves test. Rearing (vertical movements), grooming (animal cleaning its face or body), defecation, the distance travelled, time mobile and time immobile were recorded. Data were analyzed using one way ANOVA and Bonferroni test (PWL) or Kruskal Wallis and Mann Whitney U tests (open field behavior). Results: PWL significantly declined from the first to the second and third exposure to Plantar test device (ANOVA, P< 0,01; Bonferroni P< 0,05). Decline in PWL values was accompanied with concomitant increase in grooming (Kruskal Wallis P< 0.01; Mann-Whitney U test P< 0.05), decrease in rearing behavior (Kruskal Wallis P< 0.001; Mann-Whitney U test P< 0.001) and defecation during retesting sessions. Conclusion: Decrease in the PWL values obtained during reexposure to Hargreaves test device was accompanied by alterations in behavioral reactions to the new environment. Time course and direction of these changes suggest that reaction to novelty might be related to decrease in PWL values observed during retesting sessions of the Hargreaves test

The Effect of Repeated Daily Measurements on Paw Withdrawal Latencies in Hargreaves Test

The hypothesis that repeated measurements during 4 subsequent days affect withdrawal latencies in Hargreaves test was investigated. Paw withdrawal latencies to radiant heat were determined in the control, tramadol or saline group of male Wistar rats. The control group (N=10) had no treatment. Tramadol group (N=7) and saline group (N=7) received one daily intraperitoneal injection of tramadol (15 mg/kg) or saline (0.9% NaCl), respectively. A significant decline in withdrawal latencies was observed in the control group on the day 2 to day 4, when compared to day 1 (p<0.05 Bonferroni test). In the saline and tramadol groups, latencies remained stable from day 1 to day 4. During the entire testing period withdrawal latencies were 27–50% longer in tramadol group (p<0.05 ANOVA) compared with the saline group. When compared to the control group, the effect of tramadol, was noted from the second to forth day (p<0.01 Bonferroni test), but not on the first day. Finally, a tendency to decrement in withdrawal latencies existed on day 1 in the saline group compared with control group, but this difference does not reach significance. We conclude that one day of training affect withdrawal latencies in the Hargreaves test

Rat Sciatic Nerve Crush Injury and Recovery Tracked by Plantar Test and Immunohistochemistry Analysis

An experimental crush injury to the sciatic nerve, with a crush force of 49.2 N (pressure p=1.98x108 Pa), was inflicted in 30 male rats (Wistar). A control group (sham), with the same number of rats, was also operated upon exactly as the experimental group but without the crush injury. We tested the sensory and motor recovery of the sciatic nerve with Hargreaves method, using an apparatus from Ugo Basile, Italy. Testing was continued for both legs of each rat, injured and uninjured, starting preoperatively (0 day), and then 1, 7, 14, 21, and 28 days postoperatively. The same experiment was run simultaneously with the sham group. The Plantar test showed recovery of the sensory and motor function of the sciatic nerve, though not complete recovery, by 28 days. An immunohistochemical experiment was run in parallel with the plantar test on L3-L6 segments of the spinal cord from where the sciatic nerve extends. We used antibodies for Myelin-associated glycoprotein (MAG), and gangliosides GD1a and GT1b on the aforesaid part of the spinal cord. The immunohistochemical methods showed changes in sensory and motor axons in the spinal cord segment L3-L6 which suggest correspondence with the results of the Plantar test, in terms of recovery of the sensory and motor function after injury of the sciatic nerve. The immunohistochemical results also show ipsilateral and contralateral changes following injury. Results of the plantar test are suggestive that the rat shows compensation for an injury in its contralateral leg

Physical Characteristics in the New Model of the Cerebrospinal Fluid System

It is unknown which factors determine the changes in cerebrospinal fluid (CSF) pressure inside the craniospinal system during the changes of the body position. To test this, we have developed a new model of the CSF system, which by its biophysical characteristics and dimensions imitates the CSF system in cats. The results obtained on a model were compared to those in animals observed during changes of body position. A new model was constructed from two parts with different physical characteristics. The »cranial« part is developed from a plastic tube with unchangeable volume, while the »spinal« part is made of a rubber baloon, with modulus of elasticity similar to that of animal spinal dura. In upright position, in the »cranial« part of the model the negative pressure appears without any measurable changes in the fluid volume, while in »spinal« part the fluid pressure is positive. All of the observed changes are in accordance to the law of the fluid mechanics. Alterations of the CSF pressure in cats during the changes of the body position are not significantly different compared to those observed on our new model. This suggests that the CSF pressure changes are related to the fluid mechanics, and do not depend on CSF secretion and circulation. It seems that in all body positions the cranial volume of blood and CSF remains constant, which enables a good blood brain perfusion

Constitutive Serotonin Tone Modulates Molecular and Behavioral Response to Chronic Fluoxetine Treatment: A Study on Genetic Rat Model

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed medications for the treatment of mood disorders. Yet, individual response to SSRIs is highly variable, with only a portion of patients showing the desired therapeutic effect. To better understand the molecular basis underlying individual variability in response to SSRIs, here we comparatively studied behavioral and molecular consequences of chronic treatment with fluoxetine, a widely used SSRI, in two sublines of rats with constitutionally different serotonin (5HT) homeostasis: the high-5HT and low-5HT sublines. Platelet 5HT levels, a recognized indicator of SSRI efficacy, were decreased by fluoxetine treatment in both 5HT-sublines. On the other hand, biologically active plasma 5HT levels were reduced only in high-5HT rats. The anxiolytic effect of fluoxetine was also evident only in high-5HT rats, as supported by spatio-temporal and ethological behavioral measures in the elevated plus maze (EPM) test and exploratory behavior measures in the open field (OF) test. None of the behavioral EPM or OF measures were significantly altered by fluoxetine treatment in low-5HT rats. Unexpectedly, 5HT levels in cerebral cortices tended to be reduced only in low-5HT rats. Moreover, the effects of fluoxetine on cortical expression levels of 5HT-related proteins were also present only in low-5HT rats, with serotonin transporter (5HTT) and serotonin receptor type 1a (Htr1a) being down-regulated, while serotonin receptor type 4 (Htr4) was up-regulated by fluoxetine treatment. The obtained results support a role of individual 5HT tone as an important influencing factor on the biological actions of SSRI antidepressants

Bypassing major venous occlusion and duodenal lesions in rats, and therapy with the stable gastric pentadecapeptide BPC 157, L-NAME and L-arginine

AIM: To investigate whether duodenal lesions induced by major venous occlusions can be attenuated by BPC 157 regardless nitric oxide (NO) system involvement. ----- METHODS: Male Wistar rats underwent superior anterior pancreaticoduodenal vein (SAPDV)-ligation and were treated with a bath at the ligated SAPDV site (BPC 157 10 μg, 10 ng/kg per 1 mL bath/rat; L-NAME 5 mg/kg per 1 mL bath/rat; L-arginine 100 mg/kg per 1 mL bath/rat, alone and/or together; or BPC 157 10 μg/kg instilled into the rat stomach, at 1 min ligation-time). We recorded the vessel presentation (filled/appearance or emptied/disappearance) between the 5 arcade vessels arising from the SAPDV on the ventral duodenum side, the inferior anterior pancreaticoduodenal vein (IAPDV) and superior mesenteric vein (SMV) as bypassing vascular pathway to document the duodenal lesions presentation; increased NO- and oxidative stress [malondialdehyde (MDA)]-levels in duodenum. ----- RESULTS: Unlike the severe course in the SAPDV-ligated controls, after BPC 157 application, the rats exhibited strong attenuation of the mucosal lesions and serosal congestion, improved vessel presentation, increased interconnections, increased branching by more than 60% from the initial value, the IAPDV and SMV were not congested. Interestingly, after 5 min and 30 min of L-NAME and L-arginine treatment alone, decreased mucosal and serosal duodenal lesions were observed; their effect was worsened at 24 h, and no effect on the collateral vessels and branching was seen. Together, L-NAME+L-arginine antagonized each other's response, and thus, there was an NO-related effect. With BPC 157, all SAPDV-ligated rats receiving L-NAME and/or L-arginine appeared similar to the rats treated with BPC 157 alone. Also, BPC 157 in SAPDV-ligated rats normalized levels of NO and MDA, two oxidative stress markers, in duodenal tissues. ----- CONCLUSION: BPC 157, rapidly bypassing occlusion, rescued the original duodenal flow through IAPDV to SMV flow, an effect related to the NO system and reduction of free radical formation