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Tracheal disruption is a life-threatening rare complication of total thyroidectomy that it should be prevented. The own-patient risk factors, procedure of tracheal intubation and a meticulous surgical technique are three main keys to keep in mind. Both medical and surgical management of this injury depends on its size, location and patient’s symptoms although neither of them prevents late complications. An early diagnosis could improve with prognosis although it is mandatory to perform either respiratory functional or imaging study in order to assume its healing. When the tracheal laceration is diagnosed during the surgery, we should take care with a continuous monitoring of the patient’s vital signs. A good oxygenation will be succeeded in high volume and low pressure with endotracheal tube distal to the lesion. We advice placing a tube drain near the disruption to prevent emphysema and an early extubation to avoid an ischaemic damage of the mucosa. A postoperative suspicion of tracheal rupture could demand reintubation with the patient in full relaxation and an examination by CT-scan or fiberscope before deciding a simple supportive therapy. We present our therapeutic experience in a female patient who suffered from tracheal injury during total thyroidectomy and describe a review of literature.

Introduction: Presacral tumours are extremely rare entities as the asymptomatic retrorectal mass, although its clinical presentation includes infectious complications and signs of malignant degeneration. Magnetic resonance imaging is the most efficient imaging study for its diagnosis. The treatment of choice is complete surgical excision and traditional approaches are mainly through abdominal, posterior and perineal approach, depending on anatomical characteristics of the lesion. Laparoscopic excision of these retrorectal lesions has been reported in a few cases. Patients and methods: We report two cases of 38 and 24-year-old women who complained of anorectal symptoms and were diagnosed as retrorectal tumour by imaging studies. One of them was infected. Both cases were resected by means of laparoscopic techniques. There was no surgical complication and they were discharged on the 3rd and 4th postoperative day, respectively. Histopathologic findings revealed benign cystic teratoma in both cases. A follow-up after 36 months showed no recurrence. Our surgical endoscopic technique and a brief review of perioperative cares are presented and discussed. Discussion: Laparoscopic excision could be indicated in selected retrorectal tumours and a great surgeon’s resolve is always required. A meticulous dissection must be performed in order to identify and preserve vital structures. It’s only absolute contraindications seemed to be the suspicion of malignancy and operative inexperience. Conclusions: The complete laparoscopic removal of presacral lesions is a responsible surgical procedure which offers advantages from the sanitary and aesthetic point of view. This new endoscopic indication could be considered probably as a better technique than open approach in selected patients.

Porous silicon (porSi), which contains luminescent Si nanocrystal assemblies, is a promising semiconductor material for the photosensitized formation of singlet oxygen, 1 O2, for biological applications. However, because as-prepared luminescent Si nanocrystals are H-terminated and therefore hydrophobic, the first step to create a prototype of Si nanocrystalbased photosensitizer should be a modification of the Si nanocrystal surface with the aim to make it hydrophilic and able to work in a biological ambient. Such surface modification by surfactants should not, however, result in a decrease of the nanocrystals’ durability that may, in principle, take place because of surfactant-induced weakening of surface tension and the consequent increase of interaction with H2O molecules. Surfactants should not also decrease the ability of the nanocrystals to transfer the excitation energy to acceptors (first of all molecular oxygen) on their surface. These rather contradictory tasks have been largely solved in the present work by use of nonionic surfactants physically adsorbed on the porSi surface. One of the strategic objectives of nanotechnology is the development of new materials of nanometer size that have entirely new physical properties, and, therefore, new functionality. Over the last decade, tailoring of material characteristics by size control has been demonstrated for many types of semiconductors. Optical and electronic properties of semiconductor nanocrystals can be simply engineered by changing their size and composition. When electrons and holes are squeezed into a dimension that approaches a critical size, quantum-confinement effects become apparent. This effect can be seen experimentally as a widening of the semiconductor nanocrystal bandgap. [1] In case of direct-bandgap semiconductors the quantum-confinement effect is now widely used in so-called “quantum dots”, a very promising class of bright fluorescence biological labels that are able to overcome the limitations of conventional organic fluorophores. [2] In case of Si, which is an indirect bandgap semiconductor, radiative transition is forbidden, which is an inherent limitation for light-emitting applications of Si nanocrystals. Nevertheless, the same peculiarity is found to be a great advantage for photosensitizing applications, namely for the energy transfer from long-lived Si nanocrystal excitons to O2 and the production of extremely reactive excited (“singlet”) molecular oxygen, 1 O2. [3] By taking into account the broadband absorption of Si nanocrystals, [4] it be

A study of luminescence properties of water-soluble and hydrophobic porphyrin and chlorin molecules immobilized in oxidized (i.e. non-luminescent) and as-prepared (i.e. luminescent) porous silicon (porSi) layers is carried out. It is found that the oxidized porSi matrix itself does not introduce any quenching effect on the porphyrin fluorescence, but the fluorescence is subjected to the concentration quenching. At maximum porphyrin/chlorin concentration used (ca. 10 -3 M in impregnation solutions) the quenching is strong in case of hydrophobic porphyrins and sufficiently moderate for water-soluble ones, especially for cationic porphyrin TMPyP4. A concentration of the latter in porSi layer is determined by direct measurements. Both hydrophobic and water-soluble porphyrins immobilized on the surface of as-prepared porSi are found to quench the luminescence of the latter. In case of hydrophobic porphyrins the quenched porSi luminescence is regained almost to the initial value on the time scale of tens of hours, whereas in case of water-soluble porphyrins the fluorescence spectrum of the latter builds up in course of time. Possible mechanisms responsible for these effects are discussed.

A model for steady state deformation of the commercial γ′ precipitation hardened alloy A286 at moderately high temperature is presented. This model is mainly based on the theory of thermally activated glide. The activation parameters such as the maximum free energy necessary to overcome obstacles to glide, the threshold stress for jerky glide and the activation volume of the rate controlling process are derived from experimental results and allowed rationalization of all the measurements in the range of stresses and temperatures investigated. Creep tests were carried out at constant stress in the range of 180–750 MPa at 600, 640, 670 and 700 °C in air. Transmission electron microscopy has permitted determination of the size of the γ′ particles and the average distance between them.

The hydrogen trapping characteristics of 13CrNiMo martensitic steel weld metals, with different austenite contents resulting from different post-weld heat treatments, have been analysed. Scanning electron microscopy and X-ray diffraction have been used to study stable austenite resulting from intercritical tempering of these soft martensitic stainless steels weld metals. Austenite contents up to 25 vol.% have been obtained. Hydrogen diffusion and permeation coefficients have been obtained from an analysis of the permeation rate of hydrogen through these materials. A decrease of the hydrogen apparent diffusion coefficient is observed when the tempering temperature is increased in the range 400 ° C ⩽T⩽670 ° C ; this decrease is attributed to changes in the martensitic matrix as well as to the increase of austenite content. The role of the austenite phase on trapping is discussed.

The precipitation-hardened alloy A286 has been characterized as a function of ageing treatment, and the creep behavior has been studied in the temperature range of 600–700 °C and at 230–740 MPa. Microhardness tests of samples aged at different temperatures have been performed, and it was observed that the fastest precipitation kinetics of the metastable γ′ occurred during ageing at 730 °C. Further exposure at this temperature degraded the good mechanical properties of the material because the γ′ dissolved, and the stable η phase formed. Optical and scanning and transmission electron microscopy (SEM and TEM, respectively) characterization of samples in as-received state and after ageing were performed to study the microstructural development. In all creep tests, the damage observed was intergranular. The correlation between secondary strain rate and time to failure was shown to be a modified Monkman–Grant, including the elongation to rupture and an exponent different of 1 for the strain rate to obtain a better correlation. The Larson–Miller parameter has been used to correlate creep stress, temperature and rupture time for the aged material.

A failure analysis of a stop-and-control combined steam valve stem, which failed during service in a thermal power station, was performed by means of optical and electron microscopy techniques. The fractographic observations showed an intergranular decohesion indicative of a brittle fracture and that the origin of the fracture was located on the nitrided thread of the stem, which thus acted as a stress concentrator. Mechanical tests showed a low toughness of the material, due to a high density of precipitates on grain boundaries, and a heterogeneous austenitic (duplex structure) grain distribution, as revealed by light optical and electron metallographic analysis. Failure was attributed to the low toughness of the material and a nitrided layer on the roots of the threaded zone.

In previous works, extensive desulphurisation, including shape control and low hardness in segregation zones, were pointed out as effective ways for increasing resistance to hydrogen induced cracking (HIC) in steels exposed to wet H2S environment. In this study, the behaviour of eight plates was evaluated by immersing samples in H2S-saturated NACE solution. HIC susceptibility was assessed by an ultrasonic method and correlated with the elongated MnS inclusion distribution. The results allow us to remark that an extremely low sulphur level is not necessary to reach good HIC resistance, provided that no hard bands are present in the steel. Under this condition, a relationship to calculate the minimum average sulphide length which provides low HIC susceptibility was found.

Blisters were grown in Zr–2.5Nb pressure tube sections by a thermal gradient without applying external stress. The surrounding hydride distribution was analyzed. Hydride platelets were observed in the radial direction of the blister. The precipitation of these hydrides was found to be favored by low temperature of blister growth and slow cooling rate after blister formation. The misfit strain produced by hydride blister growth provides the stress necessary to promote radial precipitation. During the subsequent tensile test at 200°C (delayed hydride cracking test) the radial hydride length and thickness are increased. This increase is explained by a stress concentrator effect of the blister. When this effect vanishes, the increase of radial hydrides continues by an autocatalytic effect and stress concentrator effect of the hydride platelet. If a crack originated in the blister reaches the matrix it could propagate along a radial hydride previously precipitated.

The objective of this study was to investigate the effects of DL-malate on the in vitro fermentation of a 50 : 50 forage : concentrate diet using the rumen simulation technique (RUSITEC) and to compare these effects with those induced by the addition of propionate. The RUSITEC system consisted of eight vessels: three of them received daily 5.62 mmol of DL-malate, three vessels received daily 5.62 mmol of propionate and two vessels received no additives (control). After an adaptation period of 11 days the main fermentation parameters were determined for five consecutive days. There were no significant differences between treatments either in pH or in the daily production of NH3‐N. Compared to control diet, the addition of DL-malate resulted in an increase (p < 0.05) of hemicellulose disappearance and a trend (p < 0.10) towards a greater disappearance of dry matter, organic matter and neutral detergent fibre. Differences between DLmalate and propionate in diet degradation were not significant. DL-malate treatment resulted in an increase (p < 0.01) of daily propionate production, and a decrease (p < 0.05) in the amount of both methane (mmol/g DM fermented) and L-lactate (mg/day). Compared to propionate, DL-malate produced an increase (p < 0.05) of acetate production and tended to produce a lower amount of propionate (p < 0.10). In conclusion, these results seem to indicate that DL-malate enhanced the in vitro fermentation by increasing production of propionate and digestibility of hemicellulose. # 1999 Published by Elsevier Science B.V. All rights reserved.

The effects on the hydrogen embrittlement (HE) due to variation of the delta ferrite contents were investigated on austenitic stainless steel welds. The hydrogen distriburion in the microstructure was studied by means of the hydrogen microprint technique. The damage caused by the hydrogen was evaluated through bending and tensile tests. The ferrite-austenite interfaces act as hydrogen traps. Ferrite increases the susceptibility to hydrogen, the greater the quantity of ferrite, the more HE, which basically modifies the form in which the hydrogen damages the material: it causes the austenite to change from a normal fragile fracture to a ductile fracture, accompanying the ferrite fragile fracture.

Eleven sun-cured hays with a crude protein and neutral-detergent fibre contents ranging from 57 to 207 g kg −1 and 428 to 744 g kg −1 dry-matter (DM) respectively, were used to study the suitability of different in vitro and in situ methods to estimate the extent and rate of degradation in the rumen. The methods used to study degradation kinetics were: (1) DM disappearance when a sample of each hay was placed in nylon bags and incubated in the rumen for different lengths of time, (2) gas production (GAS) at different incubation times when hays were incubated in vitro with buffered rumen fluid, (3) DM disappearance at different incubation times in a cellulase solution (CEL), (4) sugars (SUGAR) release to the supernatant after incubation in the cellulase solution and (5) optical density of the supernatant at λ =280 nm (as indicator of phenolic compounds release) after solubility in the cellulase (PHEN). All kinetic data were fitted to first-order kinetic models. From the relationships between gas production and DM degradation in situ it was estimated that 0.295 ml (SE 0.0335) gas were produced per mg of DM degraded for incubation times beyond 24 h, although this ratio was significantly lower for short incubation times. There were significant ( P P P >0.05) correlated with those obtained by other methods. Methods in situ, GAS and CEL resulted in similar relative ranking of forages according to their degradation rate (significant Spearman rank correlation coefficients), although there were significant differences in the absolute values estimated. Those differences were larger as the legumes proportion of the hays was greater. In situ degradation characteristics can be estimated from in vitro gas production parameters, although prediction equations were different depending on the botanical composition of the hay.

The kinetics of carbide precipitation during the tempering of low-carbon martensite at 453K was studied by means of the hydrogen-permeation method. The hydrogen diffusivity obtained by this technique attained a minimum value in the quenched specimens and increased with increasing tempering time to reach a constant value between 3 and 6h. This change in the hydrogen diffusivity is attributed to modifications in hydrogen trapping due to carbide precipitation, and the kinetics of precipitation are described by a Johnson-Mehl or Avrami equation such that the precipitated carbide fraction is given by f(t) = 1 − exp(−0.06t0.36). Hydrogen-trapping modifications are explained in terms of the generation of a plastic zone when a local volume change occurs.

9 pages, 5 tables., Twenty four Churra lambs from multiple births were assigned to a 3x2 factorial design, with three levels of milk intake (837-L, 1046-M and 1255-H kJ gross energy per kg metabolic body weight per day) and two sexes (males and females). The effects of these factors on growth rate during the milk-feeding period (0 to 30 days), weaning period (31 to 37 days) and post-weaning period (38 to 77 days) were studied. The live weight gain during the milk-feeding period was statistically different (P

The surface carbide layer, interior chain-like carbide arrangements and the carbide/matrix interfaces present in an initial Zr-2.5Nb alloy were studied in hydriding and oxidation experiments. Hydriding performed by cathodic charge in 0.1 M H 2 SO 4 solution showed that neither the inner carbide chains nor the corresponding interfaces offered short circuit paths for hydrogen diffusion, while the surface carbide layer acted as a protective layer. The oxidation tests performed in autoclaves during 24 h in deaerated steam at 400°C and 105 bar showed weight gains higher than one order of magnitude with respect to the samples free of carbides. The surface carbides promoted the accelerated oxidation of the surrounding matrix and were stripped during the experiments. Evidence was found of the oxidation of the inner carbides, probably due to the transformation strain energy produced by the former oxidation of the surrounding matrix. Moreover, the carbide/ matrix interfaces acted as short circuit paths for oxygen diffusion.

Eleven sun-cured hays with a crude protein and neutral-detergent fibre content ranging from 57 to 207 and 428 to 744 g/kg DM, respectively, were studied for the relationship between in vivo DM digestibility (DMD) in sheep and estimates from chemical composition (crude protein content and Van Soest fibre analyses), in vitro Tilley and Terry technique, enzymatic (digestion by cellulase, pepsin + cellulase and neutral-detergent + cellulase), and in situ techniques (potential and effective degradabilities). On the basis of the coefficient of determination (R2) and the residual standard deviation (RSD) of the regression of in vivo DMD on the results from the investigated techniques, the neutral-detergent + cellulase method (R2 = 0.979; RSD = 0.993) and the in situ (effective degradability; R2 = 0.968; RSD = 1.21) methods gave the most precise estimate of DMD. While the in situ technique requires fistulated animals and is difficult to standardize, the neutral-detergent + cellulase method is simple and rapid, and standardized cellulases are commercially available, so that this technique could provide a suitable tool for predicting DMD of hay.

La fragilisation par l'hydrogene, en milieu H2 S aqueux, des aciers inoxydables austenitiques Z2 CND 17-12 et Z6 CN 18-09 a ete etudiee. La fragilisation des aciers a l'etat hypertrempe et sensibilise a ete caracterisee par des essais de traction lente (fragilisation dynamique). La repartition de l'hydrogene dans les facies de rupture a ete mise en evidence par micro-empreinte de l'hydrogene. Les resultats ont montre que la susceptibilite a l'hydrogene augmente au fur et a mesure que la vitesse de mise en charge diminue et que le temps de sensibilisation augmente. La valeur de l'energie de defaut d'empilement, la presence de martensite e et le transport de l'hydrogene par les dislocations semblent etre les parametres determinants de la fragilisation par l'hydrogene en milieu H2 S des aciers inoxydables austenitiques.

The effect of the microstructure on the hydrogen embrittlement susceptibility, hydrogen mobility and hydrogen distribution in a low carbon steel was studied by means of the electrochemical permeation method (electrochemical and gas charging), mechanical tests and hydrogen microprint technique. The hydrogen diffusivity attains a minimum value in a fresh martensite and diffusivity increases with increasing tempering temperature. The quantity of desorbed hydrogen is at a maximum for a fresh martensite and decreases with increasing tempering temperature. The trapping energy was estimated to be ∼ 46 kJ mol −1 . There is a direct relationship between hydrogen embrittlement susceptibility and the quantity of desorbed hydrogen as well as between the hydrogen segregation and crack location. The steady state flux is maximum for a normalized state. These facts can be explained in terms of hydrogen trapping process.

Young's moduli of AISI 1005 and 1070 steels, in different metallurgical states, were measured before and after hydrogen charging by means of the classical resonant bar method. Different decreases in Young's modulus were found which could be correlated with the microstructural state of the steel. The maximum diminution of elastic modulus was observed for the martensitic structure of 1070 steel (−1.7%) and the minimum in 1005 steel in the normalized state (−0.4%). Moreover a linear relationship was established between the change of Young's modulus from the effect of hydrogen and the hydrogen embrittlement susceptibility of these steels.

SUMMARYHerbage samples were collected in late June, and again in early September (1987) from permanent mountain meadows situated in North-western Spain (León). Botanical composition was determined by grouping the species into grasses, legumes and herbaceous ‘weeds’. Rumen degradability of the dry matter (DM), crude protein (CP) and neutral detergent fibre (NDF) of the botanical groups in each harvest season was determined by the nylon-bag technique.Grasses and legumes differed in their degradation characteristics, and the comparisons between forage species were different for the two harvest seasons. There were no significant differences between September grasses, June legumes and September legumes in the potential degradabilities of the DM (86·9, 87·1 and 88·4%) and CP (94·2, 92·4 and 93·8%). The NDF of grasses harvested in September was degraded to a greater extent (80·6%) than that of legumes from both harvests (70·9 and 73·6% in June and September respectively). However, June grasses showed significantly lower potential degradabilities for the DM (77·0 %), CP (84·3%) and cell wall (65·9%). Legumes were degraded at a faster rate than grasses (mean DM degradation rates of 0·143 and 0·057 respectively), and lag times were longer for grasses (4·7 h) than for legumes (2·5 h). Rumen degradation characteristics of the herbaceous ‘weeds’ were estimated, but it should be remembered that many other factors may limit their utilization by ruminants.It was concluded that the major constraint to the nutritive value of these permanent swards would be the maturity of the grasses harvested in June, which markedly reduced the rumen degradability of the forages.

An irrigated permanent mountain meadow (Leon, Spain) was cut twice in 1987, in late June, and again in early September after the summer regrowth. Herbage harvested from each season was preserved by different methods, namely freezing (fresh), ensiling in plastic bags (silage) and sun-curing (hay). Rumen degradation characteristics were determined by the nylon bag technique. Forages harvested in September had a higher crude protein (CP) concentration (153 v. 104 g/kg dry matter (DM)) and a lower cell wall concentration (467 v. 599 g/kg DM) than those from the June cut, resulting in a greater DM potential degradability (0·856 v. 0·751) and a faster degradation rate (0·088 v. 0·057 per h). Method of conservation did not affect the CP concentration of the forages, but had a significant effect on their nitrogen (N) solubility and protein degradability. Hay had the lowest N solubility (0·388) and CP degradability. Ensiling led to an increase in the N solubility (0·668 v. 0·554) compared with the fresh control, resulting in a higher effective degradability of CP estimated for different rates of passage. Forage conservation caused a slight increase in the relative proportion of the cell wall in the total DM (mean neutral-detergent fibre concentrations for fresh forage, hay and silage were 510, 548 and 536 g/kg DM, respectively) presumably due to loss of cell contents. Potential DM degradabilities of fresh forage, hay and silage were similar (0·805, 0·813 and 0·791 respectively). Although hay seemed to be degraded to a greater extent and at a faster rate than the other two types of forages, the rumen degradation characteristics were not consistently affected by the method of conservation to an extent that could have important nutritional implications.

Shot-peening surface treatments were performed on a low-carbon steel and a 304 stainless steel. The influence of residual stresses on hydrogen permeation and distribution was investigated. The results were correlated with the tensile properties measured in air after cathodic charging and in a NACE medium under slow load-rate straining. The role of shotpeening on the hydrogen embrittlement of the low-carbon steel is strongly dependent on the severity of the hydrogen environment and testing conditions. The detrimental effect of shotpeening on the hydrogen embrittlement of the stainless steel is related to phase transformations induced by cold work.

The effect of the microstructure on the hydrogen embrittlement susceptibility, hydrogen mobility and hydrogen distribution in a low carbon steel was studied by means of the electrochemical permeation method (electrochemical and gas charging), mechanical tests and hydrogen microprint technique. The hydrogen diffusivity attains a minimum value in a fresh martensite and diffusivity increases with increasing tempering temperature. The quantity of desorbed hydrogen is at a maximum for a fresh martensite and decreases with increasing tempering temperature. The trapping energy was estimated to be ∼ 46 kJ mol −1 . There is a direct relationship between hydrogen embrittlement susceptibility and the quantity of desorbed hydrogen as well as between the hydrogen segregation and crack location. The steady state flux is maximum for a normalized state. These facts can be explained in terms of hydrogen trapping process.

In the last few years there has been an increasing concern regarding the use of antibiotics in ruminant feeding and the potential for selection of antibiotic-resistant pathogen micro-organisms. Some authors (Martin and Streeter, 1995; Callaway and Martin, 1996) suggested that organic acids (aspartate, fumarate, malate) potentially provide an alternative to currently used antimicrobial compounds. Several in vitro studies (Martin and Streeter, 1995; Callaway and Martin, 1996) showed that incorporation of DL-malate into fermentations with both Selenomonas ruminantium HD4 and with mixed ruminal micro-organisms resulted in changes in final pH, methane and volatile fatty acids (VFA) that are analogous to ionophore effects. Nisbet and Martin (1993) hypothesized that malate acted as an electron sink for hydrogen. However, the mechanism of action is not well known. Malate is a key intermediate in the succinate-propionate pathway and therefore could stimulate propionate production. The objective of this study was to study the effects of DL-malate and propionate on the in vitro rumen fermentation of a 50:50 foragexoncentrate diet.The study was carried out using the rumen simulation technique (RUSITEC) following the general incubation procedure described by Czerkawski and Breckenridge (1977). The complete unit consisted of eight vessels with an effective volume of 700 ml each. The vessels inocula (solid and liquid) were obtained from three ruminally fistulated ewes given a diet consisting of 700 g alfalfa hay and 300 g concentrate per kg dry matter (DM) (Table 1) and transferred to the RUSITEC system within 30 min of the 1st day of the experiment. The flow through the vessels was maintained by continuous infusion of artificial saliva at a rate of 533 ml/day. Each vessel received daily a nylon bag containing 7 g alfalfa hay, 7 g concentrate and 0·10 g vitaminsminerals mix. From the 1st day of incubation three vessels received daily 5·62 mmol DL-malate (disodium salt; Sigma-Aldrich Quimica, S.A., Spain), three vessels received 5·62 mmol of propionate (monosodium salt; Sigma-Aldrich Quimica, S.A., Spain) and two vessels received no addition (control). DL-malate and propionate were weighed into the nylon bags and carefully mixed with the food.

To improve esophagectomy outcome, preoperative identification of high-risk patients should allow the surgical approach to be modified or alternative treatment methods to be employed.Preoperative risk assessment of 114 patients with resected esophageal cancer. One half of the cases affected the middle third of the esophagus. The tumor stage was III (33.3%) or IV (29.8%). The combined thoracoabdominal approach was the preferred route for resection (88.6%). We analyzed the influence of different variables (epidemiological, clinicopathological and surgical) affecting postoperative mortality.Sixty-six (57.9%) patients developed postoperative complications, mainly pulmonary. The mortality rate was 12.3% (14 patients). Multivariate analysis of preoperative variables found significant association between postoperative death and previous neoplasm (p=0.01), liver cirrhosis (p=0.001), abnormal functional respiratory test (p=0.01) and low serum cholesterol (p=0.005) and albumin (p=0.01). Using those variables, we created a composite scoring system that provides a separation of patients into three postoperative death risk groups. If this knowledge was used, we could avoid 50% of postoperative mortality via improved patient selection.The development of risk scales based on preoperative mortality risk factors may be useful in the selection and preparation of patients suitable for esophageal resection in order to diminish postoperative mortality.

Quantitative expressions of the kinetics of digestion are needed to estimate more precisely the quantity and composition of nutrients digested from feeds and their subsequent efficiency of utilization by the animal (Mertens, 1993). Degradation kinetic parameters are estimated by fitting appropriate models to data resulting from the measurement of either the undigested residue or the fermentation end-products after exposure of the feed to digestion. Kinetic data can be collected using either in vitro or in situ procedures. The in situ porous synthetic fibre bag technique has been extensively used to describe the kinetics of feeds degradation in the rumen. Several in vitro gas production methods have been developed to assess fermentation kinetics. The aim of this work was to study the relationship between rumen degradation parameters of forages determined either by the in situ procedure or by the gas production technique and to evaluate the potential of gas production measurements to assess the extent of dry matter degradation in the rumen.

Eleven sun-cured hays were used to study the suitability of different in vitro methods to predict their voluntary dry matter (DM) intake (VDMI; g DM/kg liveweight) and in vivo DM digestibility (DMD; g/kg). The methods used were: (1) gas production at different incubation times when hays were incubated in vitro with buffered rumen fluid, (2) DM disappearance at different incubation times with cellulase (CEL), (3) release of sugars to the supernatant after incubation with cellulase, and (4) optical density of the supernatant at λ = 280 nm (as an indicator of phenolic compounds release) after incubation with cellulase. All kinetic data were fitted to first-order kinetics models to estimate the rate of degradation and the potential degradability, and the average degradation rate and effective degradability (ED) were calculated. The most accurate prediction of VDMI was by using the average degradation rate of the CEL method in a single regression equation, which accounted for 0.78 of the variation in intake (residual s.d. = 1.40). When only data from grass-rich hays were considered, the inclusion of potential degradability and rate of degradation of the CEL method in a multiple regression equation accounted for 0.98 of the variation in intake (residual s.d. = 0.32). The ED of the CEL method explained 0.93 and 0.92 of the variation in the in vivo DMD for all hays and grass-rich hays, respectively (residual s.d. = 18.1 and 21.7, respectively). The predictive ability of the different methods is discussed and compared with that of the in situ technique that has been previously reported.

The utilization of forage for ruminants is associated with prolonged retention times within the digestive tract, especially when they are consumed at low levels of intake. The nutritive value of forage is influenced by both the rate at which it is degraded in the rumen and the rate of its physical removal from the rumen. These two parameters are associated with the cell wall constituents of the forage, since its cell content is rapidly fermented in the rumen and hence does not occupy space for a long.The purpose of the present expedients was to establish the relationships between the cell wall chacacterisitcs (composition and rumen degradation) of some hays and its retention time in the rumen.

The distribution of carbon in the microstructure of the twinned martensite of Fe-23 Ni-0.4 C, has been studied by microautoradiography of radioactive carbon 14. A statistical analysis of the autoradiographs, observed in the scanning electron microscope for massive specimens or in the transmission electron microscope for thin foils, show that: (i) clustering of carbon in the twin boundaries of the martensite plates occurs rapidly by ageing at room temperature; (ii) two twinning systems may be active sites for carbon clustering in the same plate; (iii) carbon segregation seems more pronounced in twin boundaries than in martensite-martensite, martensite-austenite, or mid-rib interfaces; (iv) the precipitation of ∈-carbide by ageing at 100 and 150° C is confirmed.

A process aimed at concentrating aqueous dilute solutions of metallic cations is presented. This process is an extraction-reextraction sequence using an anionic surfactant microemulsion. A quantitative assessment of a complete extraction- reextraction cycle on aqueous solution of nickel (5000ppm) is given. The microemulsion phase is made with sodium dodecyl sulfate, n-decane, l-pentanol, and an aqueous solution of NiCl2. Preliminary phase diagram determinations are presented. They state the influence of temperature and“salinity” on the phase behaviour. By measuring the concentration of the all components in every appearing phase, effective ion exchange is pointed out and discussed. It is shown that an adequate combination of extraction-reextraction steps leads to a final concentration of nickel in the final aqueous phase three times larger than the original concentration.

In the present work the hydrogen embrittlement susceptibility in austenitic stainless steel weld metals is investigated. The role of δ ferrite and sulphur segregation in hydrogen cracking is pointed out. The influence of austenitic stability is also analyzed.

Eleven sun-cured hays with crude protein (CP) and neutral-detergent fibre (NDF) concentrations ranging from 57 to 207 and 428 to 744 g/kg dry matter (DM) respectively, were used to study the relationship between the DM and NDF degradation characteristics and the voluntary DM intake (VDMI) by sheep.The VDMI was measured in the last 10 days of a 21-day period using 50 mature ewes in five groups of 10 ewes per group, with a mean live weight (LAY) of 55 kg and ranged from 41·2 to 69·8 g/day per kg LW075. Disappearanc e rates of DM and NDF were measured by incubating samples in nylon bags in the rumens of three hay-fed rumen-cannulated ewes for 3, 6, 9, 15, 24, 48 and 72 h and by fitting the exponential model Y = a + b (1 — e-ct) to the results. Potential degradabilities (defined as a + b) for DM and NDF ranged from 679 to 868 and from 445 to 808 g/kg respectively.The VDMI was significantly correlated with the soluble fraction of DM (aDM; P < 0·05) and the rate of degradation of DM (cDM; P < 0·01) and NDF (cNDF; P < 0·01). The inclusion of aDM and cDM ni a multiple regression model resulted in the equation: VDMI = 21·3 + 0·0733 (s.e. 0·01577) aDM + 138 (s.e. 26·0) cDM (R2 = 0·897; residual s.d. = 2·79), with a significant increase of the variance explained by one single degradation characteristic (P < 0·05). The prediction was not improved by adding the constant cNDF to the equation (P > 0·05). These results indicate the possibility of predicting the VDMI of hays by sheep from the rumen soluble fraction (aDM) and the rate of degradation (cDM) of DM.

The need to change the current paradigm from linear economy to circular economy makes the recovery of resources from waste effluents one of the current and future technological priorities. In this context, sewage sludge represents a great challenge and at the same time a great opportunity for the recovery of resources, both material, and energy. Within the framework of the H2020 SMART Plant project, BETA Tech. Centre is developing two technologies to maximise resource recovery from different types of sludge. Firstly, phosphorus-rich biofertilisers are being produced through advanced dynamic composting processes treating sludge from EBPR and SCENA processes. Secondly, cellulose-rich sludge is being treated through biodrying processes to produce biomass fuel with a calorific value similar to that of pine chips. &nbsp

The need to change the current paradigm from linear economy to circular economy makes the recovery of resources from waste effluents one of the current and future technological priorities. In this context, sewage sludge represents a great challenge and at the same time a great opportunity for the recovery of resources, both material, and energy. Within the framework of the H2020 SMART Plant project, BETA Tech. Centre is developing two technologies to maximise resource recovery from different types of sludge. Firstly, phosphorus-rich biofertilisers are being produced through advanced dynamic composting processes treating sludge from EBPR and SCENA processes. Secondly, cellulose-rich sludge is being treated through biodrying processes to produce biomass fuel with a calorific value similar to that of pine chips.

Ability to predict accurately the intake of digestible nutrients by ruminants is of great interest. The feed intake can be limited mainly by the amount of undigested residue remaining in the rumen. Ingested feed disappears from the rumen in two ways: through digestion and through passage. So, forages with easily degraded cell-walls, may promote faster rates of digestion and passage and allow the animal to consume more feed (Hovell et al., 1986).The objective of the present study is to determine the rate and extent of rumen degradation of various hays “in situ” and to evaluate the ability to predict the voluntary intake from these rumen degradation characteristics.Eleven sun-cured hays from three cultivars (alfalfa, red-clover and vetch-cereal), two sown grasslands (grass-clover mixture and mixed grass sward) and six permanent meadows were used to study the relationship between some rumen degradation characteristics and the voluntary dry matter intake (VDMI) by sheep.