Nanoscale heterojunction systems consisting of fullerenes blended with conjugated polymers are promising materials candidates for achieving high performance organic photovoltaic (OPV) devices. In order to understand the phase behaviour in these thin film devices, we have used neutron reflectivity to determine the behavior of model conjugated polymer-fullerene mixtures. Neutron reflectivity is particularly useful for these types of thin film studies since the fullerenes generally have a higher scattering contrast with respect to most polymers. We are studying model bulk heterojunction (BHJ) films based on mixtures of poly(3-hexyl thiophene)s (P3HT), a widely used photoconductive polymer, and different fullerenes (C60, PCBM and bis-PCBM). We have used neutron reflection measurements to determine the film morphology normal to the film surfaces in real device configurations. The novelty of the approach over previous studies is that the BHJ layer is measured with the confining films of PEDOT/PSS and Al in place. Using this model system, we have measured the effect of typical thermal annealing processes on the film development as a function of the polythiophene-fullerene mixtures.

The electronic structure of CeAg2Ge2 single crystal has been investigated by using resonant valence band photoemission and angle-resolved photoemission spectroscopy at different photon energies. Resonant photoemission has been observed near the 4d threshold of Ce at 121 eV. The constant initial state spectra show two photoemission features having 4f character near the Fermi level that exhibits Fano-like sharp resonance profile. Experimental energy bands have been mapped from the normal-emission photoelectron spectra of CeAg2Ge2 (001) surface along the Γ–Z direction. Four photoemission features are observed to show the dispersion related to the Ce 4f states and the hybridized Ag 4d with Ge 4p states. The experimental spectra have been interpreted with the help of calculations based on full potential linear augmented plane wave method using density functional theory.

Over a 2-year period, 25 families comprising of 181 individuals of all ages were longitudinally observed for the excretion of Campylobacter species. Faecal samples were taken from all persons with diarrhoea. Specimens were also taken from apparently healthy individuals and from domestic animals living within the confines of the study families at monthly intervals.

The overall diarrhoea attack rate was 19 episodes per 100 person-years with peak incidence in the 1- to 4-year-old age group (76/100 person-years). Eight (11·5%) of the total episodes were campylobacter-associated and the overall rate of campylobacter positive diarrhoeal episodes were 2·2 per 100 person-years. Of the 1002 stool samples from healthy individuals 32 (3·2/100 samples) were positive for campylobacter. The organism was most frequently isolated from children under 1 year of age both during diarrhoeal episodes (11·5 per 100 person-years) and non-diarrhoeal (11·1 per 100 samples). Multiple infections in a family were rare. In 19·4% of the occasions one or more animals were campylobacter positive. However, only in 7·7% of these occasions was a human infection recorded within 1 month after the animal was found to be positive.

The study showed that the epidemiology of campylobacteriosis in this community was distinct compared to that observed in developed countries.

The occurrence of stout and stumpy crystals of biotite elongated parallel to the schistosity and showing askew cleavage is found to be due to rotation. The relation between rotation of biotite and deformation is described. Rotated biotite contains a higher amount of FeO, TiO2 and Al2O3 in comparison to the unrotated fresh and recrystallized biotite.

Fourteen strains of S. Typhi (n=13) and S. Paratyphi A (n=1) resistant to ciprofloxacin were compared with 30 ciprofloxacin decreased-susceptibility strains on the basis of qnr plasmid analysis, and nucleotide substitutions at gyrA, gyrB, parC and parE. In ciprofloxacin-resistant strains, five S. Typhi and a single S. Paratyphi A showed triple mutations in gyrA (Ser83→Phe, Asp87→Asn, Glu133→Gly) and a novel mutation outside the quinolone resistance determining region (QRDR) (Met52→Leu). Novel mutations were also discovered in an isolate (minimum inhibitory concentration 8 μg/ml) in gyrA gene Asp76→Asn and outside the QRDR Leu44→Ile. Out of 30 isolates with reduced susceptibility, single mutation was found in 12 strains only. Genes encoding qnr plasmid (qnr A, qnr B, AAC1-F) were not detected in ciprofloxacin-resistant or decreased-susceptibility strains. Antimicrobial surveillance coupled with molecular analysis of fluoroquinolone resistance is warranted for reconfirming novel and established molecular patterns of resistance, which is quintessential for reappraisal of enteric fever therapeutics.

Four sheep sustained by intragastric nutrition were used to study saliva secretion and the relationship between osmotic pressure in the rumen and net water transport across the rumen wall. Different concentrations of buffer were infused into the rumen to change the rumen osmotic pressure. Salivary secretion was estimated from entrance of P into the rumen. Net water transport across the rumen wall was calculated as the difference between water inflow and water outflow from the rumen. A negative linear relationship between the rumen osmotic pressure (X, mOsm/kg) and the water absorption across the rumen wall (Y, ml/h) was found: Y = (394 SE 8·3)–(l·22 SE 0·03) X, r20·83, (P < 0·001), and a positive linear relationship was found between the rumen osmotic pressure (X, mOsm /kg) and the outflow rate of rumen fluid (Y, ml/h): Y = (34·0 SE 8·0) + (0·97 SE 0·03), X, r2 0·56, (P < 0·001). The implication is that rumen osmotic pressure can be a key factor in the control of the net water transport across the rumen wall, the outflow of rumen fluid to omasum and the rumen liquid dilution rate. A method is suggested by which salivary secretion in sheep may be calculated from the water balance in the rumen.

The effects of changing rumen osmotic pressure (OP) upon water kinetics and volatile fatty acid (VFA) absorption in the rumen of sheep were studied in two 4 × 4 Latin square experiments, each using four lambs with a rumen cannula and an abomasal catheter. In both experiments the lambs were sustained by the intragastric infusion of all nutrients (VFA, Ca, P, Mg and a buffer solution into the rumen, and casein, vitamins and trace elements into the abomasum). On experimental days, which were at least 1 week apart, drinking water and the casein infusion were withdrawn, and the ruminal OP was changed and held constant for 9·5 h, by incorporating NaCl at different concentrations in the buffer solution being infused. In Expt 1 the target OP values were 300, 340, 380 and 420 mosmol/kg, and in Expt 2 were 261 (no saline addition), 350, 420 and 490 mosmol/kg. Using soluble non-absorbable markers (PEG in continuous infusion and Cr-EDTA injected in pulse doses) rumen volume, liquid outflow rates, apparent water absorption through the rumen wall and VFA absorption rates were estimated at six sampling times corresponding to the 1·5 h intervals during the last 7·5 h following the change in rumen OP. Liquid outflow rate (F; ml/h) showed a significant and positive linear relationship with the rumen OP (mosmol/kg), resulting in the equation F = 1·24 OP (SE 0·096)–36·5 (SE 36·6) (r2 0·96). Similarly, water absorption rate (W; ml/h) was significantly affected by rumen OP, and this relationship was given by W = 395 (SE 39·9) −1·16 OP (SE 0·105) (r2 0·95), which means that for an OP of 341 mosmol/kg the net movement of water across the rumen wall would be zero, and either a net efflux or a net influx of water would be observed with lower or higher OP respectively. In Expt 2 there was a significant linear effect of OP on rumen volume (P <0·01), with higher OP being associated with increases in rumen liquid contents of about 10–20%. As rumen OP was increased there was also a decline in the absorption rate of VFA (from 232 mmol VFA/h for OP 350 to 191 mmol/h for OP 490 mosmol/kg), resulting in the accumulation of VFA (especially acetate) in the rumen and a consequent fall in rumen pH. Rumen OP seems to be important in defining water movement across the rumen wall and, hence, partitioning between absorption and outflow.

1. Wether lambs of 29–44 kg live-weight, totally nourished by the infusion of volatile fatty acids (VFA) into the rumen and casein into the abomasum, were given five treatments in consecutive periods. The treatments were (daily amounts per kg live weight (W)0.75): (a) high-protein for 7 d (2500 mg nitrogen, 650 kJ VFA); (b) low-protein for 7–15 d (525 mg N, 650 kJ VFA); (c) N-free for 7 d (no N, 450 kJ VFA); (d) very-low-protein for 24–28 d (300 mg N, 400 kJ VFA); (e) high-protein for 40 d (2500 mg N, 650 kJ VFA). Nine lambs were subjected to treatments (a), (b) and (c) (Expt 1) and four of the lambs additionally received treatments (d) and (e) (Expt 2).

2. In Expt 1 all nine lambs had a positive N retention on treatment (a) but abrupt change to treatment (b) resulted in substantial negative N balances initially, and a period of approximately 5 d adaptation was required before N equilibrium was re-established. Animals again exhibited negative N balances when the N-free infusion (treatment c) was introduced and during that period there was no evidence of adaptation. Basal urinary N excretion was estimated to be 356 (SE 12) mg N/kg W0.75.

3. In Expt 2 all four lambs were depleted of N when receiving the very-low-protein treatment (d). The progressively decreasing N losses recorded during days 1 to 12 of the treatment period were slightly greater than those recorded during days 13 to 28 but the difference between the means was not significant (P > 0.05). There was no evidence of an adaptation in N retention between days 13 and 28 of the treatment. As assessed during days 13 to 28 of the treatment the efficiency of utilization of infused casein N was 1.0; this compared with a value of 0.66 recorded during treatment (b) in Expt 1. Live weight loss during the period of N depletion was 101 (SE 27) g/d.

4. When lambs were given treatment (e) during the last period of Expt 2, N repletion was rapid and complete within a few days. Ten days after the introduction of the treatment the rate of N retention was estimated to be 1019 (SE 38) mg/kg W0.75 per d and this value declined at a rate of 9.5 (SE 1.9) mg N/kg W0.76 per d for the following 30 d. In comparison, N retention determined for the high-protein treatment in Expt 1 was 724 (SE 66) mg N/kg W0.75 per d. Live-weight gains during N repletion were 292 (SE 26) g/d.

5. It is concluded that N-depleted lambs can replete rapidly and that enhanced N accretion (compensatory growth) may persist for 4–5 weeks. If the improved efficiency of utilization of infused N observed during N depletion reflects a changed basal N requirement, the validity of simple factorial systems for estimating N requirement is called into question.

1. Two experiments are reported in which the effect of the intragastric infusion of non-protein energy on fasting nitrogen losses was studied. Expt 1 was a preliminary trial with two 35 kg lambs given 0, 144, 288 or 432 kJ/kg live weight (W)0.75 per d as lipid or glucose infused into the abomasum for periods of 3 d. Expt 2 was of a 4 x 4 Latin square design with four sheep of about 30 kg live weight. The four treatments were control (fasted with water infusion), or the infusion of 144 W/kg W0.75 per d as glucose or lipid into the abomasum or as acetic acid into the reticulo-rumen.

2. Compared with the fasted control, glucose infusion reduced (P < 0.05) N excretion to about 0.6 of that of the control, increased (P < 0.05) plasma glucose, decreased (P < 0.05) plasma urea and β-hydroxybutyrate, and was without effect on plasma amino-N or creatinine excretion.

3. Lipid and acetate infusions were without statistically significant effect on N or creatinine excretion or any of the blood indices measured, with the exception of plasma glucose which was reduced (P < 0.05) with acetate infusion.

1. The nitrogen balance and creatinine excretion of wether lambs of 30–48 kg, wholly nourished by the intragastric infusion of nutrients, were measured in two experiments. Four lambs were used in each experiment. In Expt 1 a constant amount of casein was infused into the abomasum (640 mg N/kg body-weight (W)0·75 per d) and the amount of volatile fatty acids (VFA) infused into the rumen ranged from 0 to 670 kJ/kg W0·75 per d as six increments. Expt 2 was of similar design but two levels of casein were infused (530 and 1060 mg N/kg W0·75 per d) and, with each level of casein, VFA infused ranged from 0 to 700 kJ/kg W0·75 per d as seven increments.

2. Daily creatinine excretion was not constant, but varied between 2-d means with standard deviations of between 7·1 and 16·5% (average 13·1%) of the over-all means. There was an apparent correlation between creatinine excretion and the amount of energy infused in six out of eight lambs. There was no effect of the amount of casein infused.

3. In both experiments N balance was negative only when the amount of energy infused was substantially below published values for energy maintenance. In Expt 1, N equilibrium was calculated to be achieved at a gross (VFA plus protein) energy infusion level of 162 (SE 29) kJ/kg W0·75 per d. In Expt 2 it was observed that, at a given level of energy infusion, N retention was greater when the amount of energy had been increased from the previous level, than when it had been decreased.

4. It is concluded that the animal appears to allocate available amino acids to protein synthesis, rather than to oxidation, even when in negative energy balance. It is also concluded that the enhanced N retention observed when the amount of energy infused had been increased represented compensation after a period of energy restriction.

1. Two dairy cows were maintained by intragastric infusion of volatile fatty acids and casein. Except when fasting, the casein-nitrogen was held constant, while total gross energy supply was varied from zero during fasting to 650 kJ/kg body-weight (W)0·75.

2. One cow was estimated to attain zero N balance at an energy intake of 255 kJ/kg W0·75 and the other at 307 kJ/kg W0·75, which was calculated to be substantially below the estimated energy required for zero energy balance.

3. When the cows were later given an N-free infusion for a period preceding the trial, N balance occurred at 98 kJ/kg W0·75 for one cow and 115 kJ/kg W0·75 for the other.

4. Four steers were similarly nourished by intragastric infusion and the energy nutrient increased from 0 at fasting to 450 kJ/kg W0·75. The protein was held constant at 1 g N/kg W0·75 except at fasting. The energy level at which N balance occurred was 154 (SE 38) kJ/kg W0·75 or approximately equal to the energy content of the protein. The practical implications of these findings are discussed.

1. Two experiments are reported. In Expt 1, five male lambs of 26–33 kg were used to measure basal nitrogen excretion when the lambs were entirely sustained by an intraruminal infusion of 450 kJ/kg body-weight0·75 per d of volatile fatty acid (VFA) and were receiving no protein. In Expt 2, which was a conventional growth trial, the response to fish meal (66 or 132 g dry matter/d) of lambs given a control diet of sodium-hydroxide-treated barley straw was measured.

2. In Expt 1 the mean basal N excretion of the lambs was 429 (SE 21) mg N/kg body-weight0·75 per d. This exceeds current UK standards for the amino acid N of microbial origin which would be made available to the normally-fed host animal at a maintenance level of metabolizable energy intake.

3. In Expt 2 there was a clear growth response to the fish meal, which was greater (P < 0·05, single-tailed test) than that to be predicted from the energy content of the fish meal. There was no effect of fish meal on the voluntary intake of the basal diet, but there was a suggestion that the digestibility of the basal diet was improved.

4. It is concluded from Expt 1 that the basal requirement for amino acid N by lambs is three- to fourfold that currently recommended in the UK. This higher basal requirement should have resulted in a marked response to supplemental protein in Expt 2. The fact that the growth response in Expt 2 was less than anticipated may have been due to a combination of a slightly lower basal N excretion than that found in Expt 1, a higher yield of amino acids of microbial origin than current UK standards predict, and possibly to a change in the body composition of the lambs.