► This study was conducted to determine the effect of the thermal modification process in hot-press on the wettability and surface roughness characteristics of the eucalyptus wood board. ► The ...roughness measurements, average roughness (
R
a), and maximum roughness (
R
max) were performed based on both parallel and perpendicular to the grain using a fine stylus tracing technique. ► Contact angle measurements were obtained by using a goniometer system connected with a digital camera and computer system The results showed that surface roughness values of the modified wood boards using hot-press significantly decreased with increasing press pressure and with decreasing temperature. ► The contact angle measurements indicated that the thermal modification had a significant influence on the siarface wettability of the wood boards Statistical analyses showed significant differences an the surface roughness and contact angle values of the wood boards following thermal modification. ► The results acquired in the present work provide important information for future research and utilization of the thermally modified wood boards.
The aim of this study was to investigate the effect of the thermal modification process by hot-press on the wettability and surface roughness characteristics of the eucalyptus wood boards. The roughness measurements, average roughness (
R
a), and maximum roughness (
R
max) were taken both parallel and perpendicular to the grain using a fine stylus tracing technique. Contact angle measurements were obtained using a goniometer system connected to a digital camera and computer system. The results showed that surface roughness values of the modified wood boards using a hot-press significantly decreased with increasing press pressure and with decreasing temperature. The contact angle measurements indicated that the thermal modification had a significant influence on the surface wettability of the wood boards. Statistical analyses showed significant differences in the surface roughness and contact angle values of the wood boards following thermal modification. The results acquired in this work provide important information for future research and utilization of the thermally modified wood boards.
This article reports the effects of heat treatment on compression strength parallel to the grain, the surface roughness average roughness (Ra), and the air-dry den-sity of wood from the river red gum ...tree (Eucalyptus camaldulensis Dehn.) planted in Turkey. Eucalyptus wood was heat-treated at temperatures varying from 120° to 180°C for durations of 2–10 h. Samples cut from the heat-treated wood were tested for air-dry density, compression strength parallel to grain, and surface roughness properties. Roughness measurements by the stylus method were made in the direction perpendicular to the fiber. Based on the findings in this study, the results showed that density, compression strength, and surface roughness values decreased with increasing treatment temperature and treatment times. Eucalyptus wood could be utilized by using proper heat treatment techniques without any losses in strength values in areas where working, stability, and surface smoothness, such as in window frames, are important factors.
Effects of temperature and press pressure on the anatomical structure of solid-wood panels produced by using Pinus sylvestris L. (Scotch pine) wood were evaluated. Solid wood panels with dimensions ...of 250 by 500 by 18 mm were hot-pressed using a laboratory hot press at a temperature of either 120°C or 150°C and pressure of either 5 or 7 MPa for 1 h. Microscopic investigations conducted by Light Microscopy (LM) and Scanning Electron Microscopy (SEM) showed that the highest deformation occurred in earlywood regions of all growth rings for each process condition and the distribution of deformation was not uniform in growth rings. Cell-wall thickness was observed to be an important factor in wood behavior during thermal compressing processes. The results showed clearly that the impact of pressure in wood structure is promoted by increased temperature. Significant densification was observed at the maximum temperature and maximum pressure condition employed in the study, and almost all earlywood layers showed cell collapse. The study revealed that a homogenous structure of growth rings with the uniform earlywood and latewood widths throughout the wood samples plays a major role in prevention of cell collapse. The results indicated that both process conditions and anatomical structure of the wood have an interaction.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Abstract Background: Children undergoing cardiac catheterization usually need general anesthesia or deep sedation. Objective: This study was performed to compare the effects of ...propofol/dexmedetomidine and propofol/ketamine combinations on recovery time and hemodynamic parameters in pediatric patients undergoing transcatheter atrial septal defect (ASD) closure. Methods: This was a prospective randomized study. Pediatric patients with ASD were randomly assigned into 2 groups to receive propofol/dexmedetomidine or propofol/ketamine. The dexmedetomidine group received an infusion over 10 minutes of dexmedetomidine 1 μg/kg and propofol 2.0 to 2.5 mg/kg bolus for induction, then an infusion of dexmedetomidine 0.5 μg/kg/h and propofol 4 to 6 mg/kg/h for maintenance. In the ketamine group, patients received the same dose of propofol and ketamine 1 mg/kg for induction and 0.5 mg/kg/h by infusion for maintenance. The procedure was performed using both fluoroscopy and transesophageal echocardiography. Hemodynamic data, respiratory rate, and oxygen saturation were recorded before and after induction, 1 and 5 minutes after intubation, every 10 minutes thereafter during the procedure, and after extubation by researchers blinded to the study drugs. Recovery time, the primary outcome, was evaluated by a modified Steward score; a score of ≥6 means that the patient is awake or responds to verbal stimuli, has purposeful motor activity, and coughs on command. The time to reach a modified Steward score of ≥6 was recorded. The secondary outcome was the effects on the hemodynamic variables. Creatine kinase musclebrain subunit, myoglobin, cardiac troponin I, and brain natriuretic peptide were the biochemical variables measured. Patients were monitored for respiratory (changes in oxygen status) and hemodynamic adverse effects (heart rate changes, blood pressure changes) until the second hour in the intensive care unit after the operation was concluded. Results: Nine patients each were randomly assigned to propofol/dexmedetomidine and propofol/ketamine. The demographic and clinical parameters were not significantly different between groups. In the dexmedetomidine group, 5 of the patients were male, mean (SD) age was 12.5 (10.4) years, and mean weight was 40.8 (27.8) kg. In the ketamine group, 3 patients were male, mean age was 10.1 (4.5) years, and mean weight was 30.0 (15.2) kg. The recovery time was significantly longer in the ketamine group than in the dexmedetomidine group (10.5 3.4 vs 5.7 0.8 minutes; P = 0.01). Systolic and diastolic blood pressure values were not significantly different between groups in any study period. Heart rate values were significantly higher in the ketamine group at 5 minutes after intubation (106.6 vs 84.2 beats/min), 10 minutes (111.8 vs 87.4 beats/min) and 30 minutes (110.0 vs 89.6 beats/min) perioperatively, and after extubation (126.8 vs 92.2 beats/min) (all, P < 0.05). In the dexmedetomidine group, one patient experienced shivering and one reported nausea; in the ketamine group, one patient reported nausea. Neither respiratory depression nor severe hypotension (ie, >20% change over baseline or requiring intervention) was observed in any patient. One patient developed agitation in the ketamine group. Conclusions: In this small study, both dexmedetomidine and ketamine in combination with propofol were well tolerated in these pediatric patients who required ASD closure. The recovery period was significantly shorter in the dexmedetomidine group.
Purpose
Extracorporeal shock wave lithotripsy (ESWL) requires sedation in pediatric patients. Dexmedetomidine is a relatively new agent used for sedation. The aim of this randomized prospective study ...was to compare the effects of dexmedetomidine–ketamine and midazolam–ketamine combinations on the recovery time, hemodynamic and respiratory variables, and side effects in pediatric patients undergoing ESWL.
Methods
Fifty pediatric patients aged between 2 and 15 years who were scheduled for elective ESWL were randomized into two groups. In Group D we applied dexmedetomidine at1 μg/kg, given over 10 min, and a bolus of 1 mg/kg ketamine for sedation. In Group M we applied midazolam at a 0.05 mg/kg bolus dose 10 min before the procedure and a 1 mg/kg bolus of ketamine. We measured and monitored the hemodynamic variables, oxygen saturation, and recovery time, and we also monitored the side effects.
Results
Four patients in group D refused to complete the study; 21 patients in group D and 25 patients in group M completed the study. We found the recovery time eye-opening time (9.3 ± 4.5 vs. 16.2 ± 6.5 min;
p
< 0.001), verbal response time (12.8 ± 4.9 vs. 19.2 ± 7.2 min;
p
< 0.001), and the cooperation time (17.1 ± 5.0 vs. 23.3 ± 7.7 min;
p
< 0.001) to be shorter in the dexmedetomidine group. Also, the heart rate values were lower in the dexmedetomidine group at the 20th minute of the procedure (99.1 ± 19.0 vs. 118.7 ± 7.3 beats/min;
p
= 0.016).
Conclusion
In this study we found the recovery time to be shorter, with hemodynamic stability, in the dexmedetomidine group, compared with the midazolam group. So we can conclude that dexmedetomidine may be a good and safe alternative agent for sedation, with a shorter recovery period than midazolam, in the pediatric population.
Various thermal modification techniques are used to improve some properties of wood materials. Thermally compressed wood (TCW) is obtained by using a hot-press. This study investigates the effect of ...thermal compression on the density, vertical density profile (VDP), moisture content (MC), thickness swelling (TS), Janka hardness, and drying characteristics of the poplar wood boards. The experimental boards were cut from poplar wood (Populus spp). The boards with dimensions of 100 mm by 500 mm by 25 mm were thermally compressed at press temperature of either 150 °C or 170 °C, press pressure of either 1 or 2 MPa for 45 minutes in a hot-press. A total of 10 experimental boards were prepared - two boards for each group plus two for control. The results obtained in this study indicated that the density and Janka hardness values increased with the increase of the press pressure. The thermal compression process decreased the thickness of the boards. The thickness reduction increased with the increase of the press pressure. An improvement was not seen in the TS values of the samples when compared to those of the untreated samples. This study revealed that the thermal compression technique should be used to improve some properties of poplar wood. In this way better use could be made of low-cost poplar wood.
Purpose
This study was designed to compare the effects of premedication with dexmedetomidine and midazolam on post-electroconvulsive therapy (ECT) agitation (which patients had experienced previously ...and had been resistant to treatment). In addition, we aimed to evaluate the duration of convulsion, the propofol requirement, the recovery time, and patients’ satisfaction during and after ECT.
Methods
Fifteen patients with depressive episodes of bipolar disorder and nonbipolar recurrent depression and patients who underwent a series of three consecutive ECT treatments were studied as a crossover design. In this double-blind and placebo-controlled study, patients were randomly allocated to receive either dexmedetomidine, 0.5 μg·kg
−1
(group Dex), midazolam, 0.025 mg·kg
−1
(group Dor), or saline (group C) in a total volume of 20 ml given intravenously 10 min before the induction of anesthesia. Propofol was administered until the patients did not respond to a verbal command.
Results
The mean duration of convulsive activity was longer in group Dex than in group C and group Dor (
P
< 0.05). The total dose of propofol requirement in group Dor and group Dex was lower than that in group C (
P
< 0.05). Agitation scores in both groups Dor and Dex were significantly lower than scores in group C (
P
< 0.05) at 10 and 15 min after ECT.
Conclusion
Premedication with low-dose intravenous dexmedetomidine, 0.5 μg·kg
−1
or midazolam, 0.025 mg·kg
−1
before ECT may be useful in managing treatment-resistant agitation after ECT, without adverse effects.
Background Myoclonic movements are common problems during induction of anesthesia with etomidate. The aim of this study was to compare the effect of pretreatment with dexmedetomidine (0.5 μg/kg) and ...thiopental (1 mg/kg) on the incidence of etomidate- induced myoclonus and postoperative pain. Materials and Methods A prospective double-blind study was conducted at a university hospital. Ninety patients (ASA physical status I-II) were randomly assigned to one of three groups: patients were pretreated with either dexmedetomidine (0.5 μg/kg), thiopental (1mg/kg), or saline before induction of anesthesia with etomidate. One minute after the injection of study drugs, etomidate, 0.3mg/kg was given. Myoclonus was assessed on a scale of 0 to 3. Recovery time, postoperative pain score, and hemodynamic variables were recorded during the intraoperative and postoperative period. Headache, nausea, vomiting, and coughing were noted during the study. Results The incidence and the intensity of myoclonus was significantly lower in the dexmedetomidine and thiopental groups (34%, 36%) than in the control group (64%) ( P <0.05). The postoperative pain score at 30min in the thiopental group was significantly higher than in the dexmedetomidine and control groups (63%) ( P <0.05). Conclusions We concluded that pretreatment with dexmedetomidine or thiopental is effective in reducing the incidence and severity of etomidate-induced myoclonic muscle movements and pretreatment with thiopental increases the postoperative pain.
Abstract Background We hypothesize that dexmedetomidine (DEX), a selective α2 adrenergic receptor agonist, may affect the intraoperative blood loss and clotting tests such as prothrombin time, ...activated partial thromboplastin time, and international normalized ratio in children undergoing adenotonsillectomy (ADT). Methods Sixty patients scheduled for elective ADT under general anesthesia. The patients were randomly assigned to receive either DEX 0.5 μg/kg (group D) or placebo bolus (group C) with a total volume of 10 mL, 10 min before the induction of anesthesia. Mean arterial pressure (MAP), heart rate, blood loss, preoperatively and immediately after awakening clotting tests, agitation, sedation, visual analog scale, and analgesic requirement, were assessed and recorded. Results The postoperative hemoglobin was significantly lower than the preoperative value in both groups ( P < 0.05). The postoperative agitation scale and analgesic requirement and visual analog scale at the 15th min were significantly lower in group D than those in group C ( P < 0.05). Total blood loss and postoperative sedation score in group D was significantly higher than that in group C ( P < 0.05). The postoperative prothrombin time, activated partial thromboplastin time, international normalized ratio tests between the groups, additionally pre-postoperative MAP, heart rate, and clotting tests were similar in each group. Conclusions The premedication with DEX 0.5 μg/kg decreased postoperative agitation, pain, and analgesic requirement without significant change in the clotting tests and MAP but increased bleeding slightly during ADT.
Background This study aimed to compare the effects of low and same dose of dexmedetomidine when added to lidocaine for intravenous regional anesthesia (IVRA) and when administered for premedication ...before IVRA. Material and Methods In this double blind study, 45 patients with ASA physical status I-II were scheduled to undergo carpal tunnel release as an outpatient procedure and were randomly divided into three groups. IVRA was performed with 40mL of 0.5% lidocaine in the operating room. A single dose of dexmedetomidine 0.5 μg/kg and placebo (saline) solution in a total volume of 20mL were administered intravenously to group P ( n = 15) and group S ( n = 15), respectively, before IVRA. 0.5 μg/kg of dexmedetomidine was added to lidocaine in group A ( n = 15) during IVRA. The onset and recovery time of sensory and motor block, intraoperative-postoperative visual analog scale (VAS) and Ramsay sedation scores (RSS), analgesic requirement, hemodynamic variables, and side effects were noted. Results Significantly shortened sensory block onset and recovery time in group P and A, shortened motor block onset time in group P, and decreased intra-postoperative VAS scores and analgesic requirement in groups P and A were found. Intraoperative RSS in group P and postoperative RSS in groups P and A were higher than in group S. Intraoperative and postoperative heart rate and postoperative mean arterial blood pressure (MAP) of group P was significantly lower than groups A and group S, respectively. Conclusion Both addition of dexmedetomidine to lidocaine and premedication with dexmedetomidine for IVRA similarly improve quality of anesthesia and perioperative analgesia without important side effects.
PDF
