COMPARISON OF THE SPECIFIC GRAVITY VARIATION OF Swietenia macrophylla, Khaya senega/ens;s AND Pau/ownia fortunei

Since the existing natural forests have become increasingly subjected to conservationpressure, forest plantations have been recognized as an alternative to meet the future~demand for sawn timber. A major drawback for the efficient utilization and promotion ofnew species such as Khaya senegalensis and Paulownia fortunei as well as muchfamiliar Swietwnia macrophy/la is the lack of information regarding their woodproperties grown under local conditions. The present work was designed to determinespecific gravity of each species, investigate the variation of specific gravity within thespecies and to determine the effect of growth rate on specific gravity.Specific gravity variations were studied in 79 year old Swietwnia macrophylla, 49 yearold Khaya senegalensis and 16 year old and Paulownia fortunei trees. Three trees wereselected from each species and pith to bark variation was investigated in sample disksremoved at breast height, 50%' and 80% heights of the bole length. Radial variationswere studied at percentage distances from the pith.The mean numerical specific gravity values obtained for Swietwnia macrophylla. Khayasenega/ensis and and Paulownia fortunei were 0.511,0.617 and 0.317 respectively andthese values suggest that the values are comparable to those earlier published data forother countries. The results of this study indicate that general pattern of radial variationof specific gravity in both Swietwnia macrophylla and Khaya senegalensis was to remainuniform from pith to bark. This pattern was evident at all the height levels. In Paulowniafortune, the radial trend was to show a gradual increase from pith to bark at all the heightlevels. The axial trend of Swietwn!a macrophyl/a was higher specific gravity at the base,drops to a minimum at mid height and increase again to a maximum at merchantabletop. Khaya senegalensis showed a gradual increase from base to top. The axial variationwas not significant in both these species. and Paulownia fortunei showed a significantreduction of specific gravity from base to top.To investigate the effect of growth rate on specific gravity, sample disks were extracted atbreast height and ring width and whole ring specific gravity were measured based on thegrowth rings identified from pith to bark. Results indicated that no substantial anddefinite relationship appears to exist between whole ring specific gravity and ring widthrepresenting the growth rate in Swietwnia macrophyl/a. Khaya senegalensis (diffuseporous)and and Paulownia fortunei (ring-porous).

VARIATION OF SPECIFIC GRAVITY WITHIN Eucalyptus grandis TREES GROWING IN DIFFERENT SITE CLASSES.

Wood is a very remarkable material with variability and flexibility The variability of woodincreases its utility It may be also a major drawback to its efficient use as raw materialTherefore understanding of pattern of wood properties within the tree has becomeimportant. In addition, growth rate and its effect on wood properties are of practicalimportance to maximize wood and fiber production. In this study, variations of specificgravity within the trees of 30-years old Eucalyptus grandis extracted from Pattipola,Saruhipura and Piduruthalagala in Nuwara-Eliya districts were studied. Data werecollected in relation to site class (growth rate) as determined by tree height. The objectiveof the study was to find out whether specific gravity is affected by growth rate of tree.Specific gravity values were collected in a systematic manner, which are essential incommercial utilization of this species. Three sites, namely Slow Growth Site (SGS),Medium Growth Site (MGS) Fast Growth Site (FGS) were chosen. Five trees from eachsite were taken for the investigation. Tree height difference between SGS (33.8 meters )FGS (45 meters) was significantly different (PS:005) but not between SGS and MGS (387meters)Variation patterns of specific gravity in racial direction were studied using two linearsections extracted across the diameter of every sample disc, from north to south and cast towest at different height levels at breast height and at 20'Yo,40%, 60% and 80% of total treeheight. 3021 wood samples of 2*2* 1 em dimensions were used for specific gravitydetermination.In general, low specific gravity values were observed at pith in all three sites. In fastgrowth site, specific gravity increased from uith; thereafter it remained constant towardsthe bark with small fluctuation. In slow and medium growth sites, however specific gravityincreased gradually towards the bark. Fast growth site maintained the highest specificgravity values throughout piths to bark The specific gravity of SGS and MGS increasedrapidly with increasing distance from pith.In general, specific gravity increased with tree height in all sites except at 20% height levelin SGS and MGS. Mean specific gravity values in SGS at breast height, 20%, 40'%, 60'Y<,and 80% height levels were 0.432, 0.431, 0433, 0.468 and 0.475 respectively. Specificgravity values for these levels in MGS were 0.441,0.435,0.467,0.477,0.542 and Specificgravity values were 0.479.0.482,0.493,0525, .J.553 for FGS respectively.

WOOD DECAYING AGARIC FUNGI AND THEIR PREFERENCE TO SOME SRI LANKAN TIMBER SPECIES.

For satisfactory use of wood products in indoors and outdoors it is necessaryto understand the agents and conditions that decay or deteriorate timber. SriLanka being a tropical Country, loss of wood due to fungal attack isrelatively high. Basidiomycetes and Ascomycetes are the major wooddestroying fungi, which cause three types of decay brown rot, white rot andsoft rot.Main objective of the study was to determine the susceptibility and resistanceof different wood species to fungal attack in the natural environment. Largenumbers of wood inhabiting fungi were found in different wood speciesobserved in natural habitats, out of these species only lignicolous agaricswere studied in the present study.These agarics were collected from indoor and outdoor habitats andmacroscopic features were studied. The microscopic examination followed,together with the documentation and photographs. The identification of theagarics was undertaken by using reliable keys, illustrations and suitabledescriptions. 22 agarics spp were identified. and out of them Lentinus sppwere identified as brown rot fungi while Armillaria mellea, Schizophyllumcommune and Pleurotus spp were identified as white rot fungi.Schizophyllum commune was found on a large number of wood speciesfollowed by genus Lentinus. The appearance of mushroom fruiting bodiescoincided with the rain. Fruiting bodies of Pleurotus reticulates, Coprinusmacropus appeared during rainy seasons while Schizophyllum commune wasfound throughout the year. Most of the wood inhabiting agarics appeared asclumps.Coprinus spp and Marasmius spp were found on old rotting logs and stumps,while Schizophyllum commune, Lentinus spp and Cantharellus spp werefound on intermediately decayed tree trunks, stumps and building timbers.Schizophyllum commune was found on outer barks as well as sapwood andheartwood regions of logs and building timber. They appeared throughout the year and fruiting bodies were fresh under moist conditions, dry and leatheryin dry seasons. Schizophyllum commune was able to attack wide range ofhardwood and softwood species.Chloroxylone swietenia, Vitex altissima, Manilkara hexandra were found tobe resistant to fungal attack; therefore could be categorized as durable timberspecies in terms of fungal decay while Swietenia macrophylla, Artocarpusheterophyllus and Pericopsis mooniana were less attacked by fungi. Heveabrasiliensis, Mangifera indica were mostly attacked by fungi and hence canbe categorized as susceptible timber species. It is recommended to usepreservative treatments for the effective utilization of these perishable timberspecies

General anaesthetic and airway management practice for obstetric surgery in England: a prospective, multicentre observational study

There are no current descriptions of general anaesthesia characteristics for obstetric surgery, despite recent changes to patient baseline characteristics and airway management guidelines. This analysis of data from the direct reporting of awareness in maternity patients’ (DREAMY) study of accidental awareness during obstetric anaesthesia aimed to describe practice for obstetric general anaesthesia in England and compare with earlier surveys and best-practice recommendations. Consenting patients who received general anaesthesia for obstetric surgery in 72 hospitals from May 2017 to August 2018 were included. Baseline characteristics, airway management, anaesthetic techniques and major complications were collected. Descriptive analysis, binary logistic regression modelling and comparisons with earlier data were conducted. Data were collected from 3117 procedures, including 2554 (81.9%) caesarean deliveries. Thiopental was the induction drug in 1649 (52.9%) patients, compared with propofol in 1419 (45.5%). Suxamethonium was the neuromuscular blocking drug for tracheal intubation in 2631 (86.1%), compared with rocuronium in 367 (11.8%). Difficult tracheal intubation was reported in 1 in 19 (95%CI 1 in 16–22) and failed intubation in 1 in 312 (95%CI 1 in 169–667). Obese patients were over-represented compared with national baselines and associated with difficult, but not failed intubation. There was more evidence of change in practice for induction drugs (increased use of propofol) than neuromuscular blocking drugs (suxamethonium remains the most popular). There was evidence of improvement in practice, with increased monitoring and reversal of neuromuscular blockade (although this remains suboptimal). Despite a high risk of difficult intubation in this population, videolaryngoscopy was rarely used (1.9%)

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

General anaesthetic and airway management practice for obstetric surgery in England: a prospective, multi-centre observational study

There are no current descriptions of general anaesthesia characteristics for obstetric surgery, despite recent changes to patient baseline characteristics and airway management guidelines. This analysis of data from the direct reporting of awareness in maternity patients' (DREAMY) study of accidental awareness during obstetric anaesthesia aimed to describe practice for obstetric general anaesthesia in England and compare with earlier surveys and best-practice recommendations. Consenting patients who received general anaesthesia for obstetric surgery in 72 hospitals from May 2017 to August 2018 were included. Baseline characteristics, airway management, anaesthetic techniques and major complications were collected. Descriptive analysis, binary logistic regression modelling and comparisons with earlier data were conducted. Data were collected from 3117 procedures, including 2554 (81.9%) caesarean deliveries. Thiopental was the induction drug in 1649 (52.9%) patients, compared with propofol in 1419 (45.5%). Suxamethonium was the neuromuscular blocking drug for tracheal intubation in 2631 (86.1%), compared with rocuronium in 367 (11.8%). Difficult tracheal intubation was reported in 1 in 19 (95%CI 1 in 16-22) and failed intubation in 1 in 312 (95%CI 1 in 169-667). Obese patients were over-represented compared with national baselines and associated with difficult, but not failed intubation. There was more evidence of change in practice for induction drugs (increased use of propofol) than neuromuscular blocking drugs (suxamethonium remains the most popular). There was evidence of improvement in practice, with increased monitoring and reversal of neuromuscular blockade (although this remains suboptimal). Despite a high risk of difficult intubation in this population, videolaryngoscopy was rarely used (1.9%)

Placement of variable-speed wind power generators in power systems considering steady-state voltage stability

This paper investigates the most suitable location to place variable-speed wind generator based wind farms in a power system considering the steady-state voltage stability. The doubly-fed induction generator (DFIG) and the full-converter wind generator (FCWG) based wind generation is considered and the inherent reactive power capability of these generators are accurately represented in the study. Steady-state voltage stability is analysed using QV modal analysis and QV curves. QV modal analysis is used to identify the weak and strong busbars in the test system. Wind power generators with different power outputs are integrated to the power system from weak and strong busbars and the impact of voltage stability is compared using QV stability margins of the busbars. The results demonstrate that adding wind generation from the weak busbars significantly increases the QV stability margin of the weak busbars. However, adding wind generation from strong busbars slightly improve the stability margin of the weak busbars. Therefore, placing wind farms in the weak busbars in a power system is favorable for the overall voltage stability. Furthermore, the results of DFIG and FCWG based wind generation are compared and the higher reactive power capability of the FCWG based wind generation to support the voltage stability is demonstrated