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TiO2 is a very promising material for integrated photonics due to its high refractive index (∼2.3 at 633nm), wide transparency window from the visible to the mid-infrared and high non-linear refractive index. However, to date, high propagation losses hinder its utilization in real-life applications. In this work, we carry out a systematic study of the different fabrication processes involved in the realization of TiO2 channel waveguides, including RF sputter deposition, electron-beam lithography and thermal annealing, showing film losses below 1dB/cm for wavelengths above 633nm and channel losses of 1-1.5dB/cm at 1550nm.

Luminescence quenching due to ion cluster formation in erbium ion doped amorphous aluminium oxide, limits the maximum doping concentration that can be incorporated into the material and, consequently, the maximum achievable optical gain. By controlling the reactive sputtering deposition parameters, layers with different morphologies can be deposited. In this work, we investigate low propagation loss poly-crystalline aluminium oxide thin films and the effect of erbium doping on the crystallinity. We have developed a reactive sputter process to reproducibly obtain high refractive index (n~1.72 at 633 nm) poly-crystalline thin films with very low slab waveguide losses from the near-UV to the midinfrared wavelength range. Slab waveguide losses as low as 1.8 dB/cm at 407 nm and less than 0.1 dB/cm at 1550 nm of wavelength have been experimentally characterized. Both the undoped and erbium doped layers were deposited by reactive sputter coating with, a set substrate temperature of 700 °C. Preliminary TEM analyses show no discernible change in the crystallinity of the doped layers with respect to their undoped counterparts. The high optical quality of this material, in combination with a potentially increased rare-earth ion doping concentration, could pave the way towards high-gain on-chip amplifiers in different wavelength ranges and efficient on-chip lasers.

Summary The effect of exposure to different UVb compact lamps on the vitamin D status of growing bearded dragons (Pogona vitticeps) was studied. Forty-two newly hatched bearded dragons (

Vitamin D is an important regulator of calcium and phosphorus homeostasis in animals. It can be acquired from the diet or synthesised de novo when skin is exposed to UVb. Vitamin D deficiency can lead to a complex of diseases collectively called metabolic bone disease (MBD). Diurnal lizards without access to UVb are prone to develop vitamin D deficiency, even when dietary vitamin D3 is provided. A trial was conducted to determine whether juvenile nocturnal lizards require access to UVb to prevent vitamin D deficiency. All leopard geckos (Eublepharis macularius) were supplemented with dietary vitamin D3. One group was exposed to low level UVb radiation (33–51 μW/cm2) from hatching until 6 months of age and a second group remained unexposed. Animals were fed ad libitum and their growth and weight gain compared with non-exposed controls. At the end of the trial, blood samples were analysed for vitamin D3 metabolites. The concentration of the vitamin D3 metabolite, 25(OH)D3, was higher in UVb exposed animals (61 ± 20 vs. 38 ± 8 nmol/L), confirming cutaneous synthesis with UVb exposure. Growth and weight gain were similar in both groups, and this, together with the absence of clinical symptoms, suggests that dietary vitamin D3 alone can meet the vitamin D requirements for growth of this nocturnal gecko, during the first six months of life. It remains to be investigated whether the higher vitamin D metabolite levels holds other health benefits for this species, such as improved bone density or immune response.

The relationship between high intake of rapidly fermentable carbohydrates and the subsequent response on plasma glucose, insulin sensitivity and clinical signs of laminitis in dairy heifers was studied. Ten dairy heifers with a mean body weight of 275 kg (SD 13.8 kg), were parallelly subjected (n=5/treatment group) to either a total mixed ration (TMR) low (LC, 130 g DM/kg) or high (HC, 480 g DM/kg) in cassava (starch). Results showed that mean DM intake, rectal temperature, heart rate, respiration rate and rumen contractions were not affected by the dietary treatments. All heifers fed the HC-TMR had diarrhea while all the heifers fed the LC-TMR had a pasty, soft consistency of feces. Three of the 5 heifers fed the HC-TMR displayed clinical signs of acute laminitis compared to none in the LC-TMR group. Mean postprandial rumen pH values of heifers fed the HC-TMR, but not the LC-TMR, were lower than 6.0 at all the time points measured. The reduction in rumen pH was associated with 49% greater concentration of total VFA and a concomitant shift from acetic to propionic acid and increased rumen lactic acid concentrations. Moreover, the HC-TMR caused greater plasma insulin levels and insulin resistance. The three laminitis animals had 1.9 greater basal plasma insulin values and a 46% lower insulin sensitivity values, respectively compared to their non-laminitis counterparts fed the HC-TMR. Insulin sensitivity was shown to be associated with clinical signs of laminitis in heifers only when plasma insulin concentrations were greater than ~ 700 pmol/L.

In equines, Cr2O3 is widely accepted as an indigestible marker, but there are health concerns regarding the carcinogenic properties of Cr2O3. Recently, TiO2 has been suggested to be an alternative digestibility marker in equines. However, a comparison between Cr2O3 and TiO2 has not been made in equines. Six Welsh pony geldings (initial BW: 254±3 kg; 7 years of age) fed chopped alfalfa hay were used to evaluate the use of TiO2 (Ti) and Cr2O3 (Cr) as markers for calculating apparent digestibility and to investigate the effect of frequency of marker administration on the measurement of digestibility values. Diets contained 4.65 kg dry matter (DM) chopped alfalfa hay supplemented with minerals, vitamins, TiO2 (3.3 g Ti/day) and Cr2O3 (3.2 g Cr/day). Ponies were dosed with either 3.3 g Ti and 3.2 g Cr once daily (DF1) or with 1.65 g Ti and 1.60 g Cr twice daily (DF2). After adaptation to the diets and procedures for 14 days, voluntary voided faeces were collected quantitatively over 7 days and analysed for moisture, ash, Ti and Cr. Apparent total tract DM digestibility (DMD) and organic matter digestibility (OMD) were calculated using the total faecal collection (TFC) and marker method (Ti and Cr). The overall mean cumulative faecal recovery of Cr and Ti (as % of intake) were 102.0% and 96.6%, respectively. Mean daily faecal recoveries of Cr as well as of Ti were not different (P=0.323; P=0.808, respectively) between treatments. Overall daily faecal recovery of Cr differed (P=0.019) from 100% when the marker was dosed once daily, whereas overall daily faecal recovery was similar to 100% for both administration frequencies when Ti was used as a marker. For both markers, the coefficient of variation of the mean faecal marker recovery between horses was lower when the markers were administrated twice per day. Across treatments, cumulative DMD and OMD estimated with Ti were similar (P=0.345; P=0.418, respectively) compared with those values determined by TFC method. When Cr was used, the calculated cumulative DMD tended (P=0.097) to be greater compared with those estimated with TFC, and cumulative OMD values were overestimated (P=0.013). Orally supplemented Ti recovery in the faeces of ponies fed chopped alfalfa hay with Ti administered once or twice daily was close to 100%, making it the preferred marker for digestibility trials in equines.