Morphological and structural effects of NaOH added to silica

The effects of addition of NaOH (from 0.5 to 3%) upon the morphological and structural properties of a commercial silica support have been investigated in the range from 300 to 780° C: samples have been characterized by means of surface area, pore volume, pore and particle size distribution measurements, chemical and X-ray analysis, electron and optical microscopy observations. Results of various techniques were allied in showing the prevalency, at the lowest temperatures (<600° C), of surface modifications involving chemical reaction and incipient sintering while at the highest temperatures (>600° C) modifications entail the entire mass which undergoes a crystallization process. The singular presence of keatite, not hitherto reported for similar systems, allowed an interpretation of the crystallization process in terms of the sequence: amorphous cristobalite (keatite) quartz.     

High-temperature chemical heat pump based on reversible catalytic reactions of cyclohexane-dehydrogenation/benzene-hydrogenation: Comparison of the potentialities of different flow diagrams

The authors compare various flow diagrams for high temperature chemical heat pumps (HTCHP) based on the reversible cyclohexane-dehydrogenation/benzene-hydrogenation reactions. A new technological flow diagram for HTCHP is suggested. The peculiarity of this diagram is a multipurpose use of hydrogen-permeable membranes. A comparative thermodynamic analysis of the flow diagrams under consideration is undertaken in order to examine the influence of various factors on the heat efficiency and coefficient of performance of the heat pump. It is shown that the use of the hydrogen-permeable membranes in principle allows one to improve the performance of the HTCHPs and to extend the field of their application in comparison with the HTCHPs based on the flow diagrams suggested earlier.     

The influence of iron in synthetic zeolites on the decomposition of perborate

Commercial Grace 4A Zeolite exchanged with Fe³⁺ ions, pumice from different geological flows and their hydrothermally derived zeolites have been characterised as to the distribution and structural configuration of the iron content. Decomposition capacity of perborate (active constituent of detergent formulations) is not only determined by the total Fe content of the zeolite but also by the oxidation state, electron configuration and coordination. For a similar oxygen coordination, structural Fe²⁺ is more active in the decomposition of perborate than Fe³⁺. Exchanged Fe³⁺ ions of zeolites exhibit higher perborate decomposition capacity than structural Fe³⁺ or the Fe³⁺ of iron oxide.     

Mechanism of O2 evolution on TiO2 photoanodes

The mechanism of O₂ evolution over titanium oxide photoanodes has been studied by relating structural properties, derived from XRD and XPS, and electrochemical properties currents, (cyclic voltammetry and flatband potentials) to the performance in PEC cells of five specimens of lowest and highest photoelectrochemical efficiency.     

Forecasting nonlinear time series with neural network sieve bootstrap

A new method to construct nonparametric prediction intervals for nonlinear time series data is proposed. Within the framework of the recently developed sieve bootstrap, the new approach employs neural network models to approximate the original nonlinear process. The method is flexible and easy to implement as a standard residual bootstrap scheme while retaining the advantage of being a nonparametric technique. It is model-free within a general class of nonlinear processes and avoids the specification of a finite dimensional model for the data generating process. The results of a Monte Carlo study are reported in order to investigate the finite sample performances of the proposed procedure.     

Evolution of chemico-physical characteristics during manufacture and ripening of Castelmagno PDO cheese in wintertime

Biochemical, volatile and textural profiles during manufacture and ripening were determined in samples of Castelmagno PDO cheese obtained from three different batches in the main artisan cheese plant of Castelmagno PDO production area. At the end of manufacture, samples were characterised by a pH of 6.57% and 52.4% moisture content. The HPLC analysis of organic acids and sugars showed the exhaustion of lactose content, while Urea-PAGE indicated extensive primary proteolysis of both β-casein and α_s1-casein. During ripening, cheeses were characterised by high degradation of β-casein and α_s1-casein, due to bacterial action. RP-HPLC profiles showed a high production of peptides eluted between 20 and 30 min. In total, 92 volatile compounds were identified in cheese headspace. Texture profiles showed an increase in hardness, gumminess, chewiness and adhesiveness values, as well as a decrease in cohesiveness during ripening.     

Reproductive performance of dairy cows resynchronized after pregnancy diagnosis at 31 (±3 days) after artificial insemination (AI) compared with resynchronization at 31 (±3 days) after AI with pregnancy diagnosis at 38 (±3 days) after AI

An important part of reproductive management programs on dairy farms is identification of nonpregnant cows and early re-insemination to achieve higher pregnancy rates. The objective of this study was to compare the effect on reproductive performance and pregnancy loss of 2 pregnancy diagnosis protocols: (1) pregnancy diagnosis performed 31 ± 3 d after artificial insemination (AI) by ultrasonography (ULTRA), and (2) resynchronization started 31 ± 3 d after AI but with pregnancy diagnosis performed 38 ± 3 d after AI by palpation per rectum (PALP). Cows were randomly allocated into 1 of the 2 management programs. For cows enrolled in ULTRA, the initial pregnancy diagnosis (P1) was performed by transrectal ultrasonography at 31 ± 3 d after AI, and nonpregnant cows were enrolled in the Ovsynch protocol for resynchronization of ovulation to receive timed AI (TAI). For cows enrolled in PALP, the Ovsynch protocol for resynchronization of ovulation to receive TAI was initiated at 31 ± 3 d after AI regardless of pregnancy status, with the initial pregnancy diagnosis (P1) performed by palpation per rectum at 38 ± 3 d after AI. For both groups, reconfirmation of pregnancy was performed by palpation per rectum at 63 ± 3 d after AI (P2). Cows were inseminated after detection of estrus by use of activity monitors at any time during the study. Two levels of activity were used as a reference for cows AI after detection of estrus based on activity: an activity level of ≥2 when a cow was coded in DairyComp 305 (Valley Agricultural Software, Tulare, CA) as open (nonpregnant) and an activity level of ≥3 when the pregnancy status of the cow was unknown. Our findings showed that the odds of pregnancy loss cows in ULTRA was 2 times higher between P1 and P2 compared with that of cows in PALP. Furthermore, pregnancy diagnosis method (ULTRA vs. PALP) did not have a significant effect on the Cox proportional hazard of pregnancy at P2. The occurrence of assisted parturition, metritis, or retained placenta was associated with a reduced hazard of pregnancy at P2. An economic analysis was performed by simulating a 1,000-cow commercial dairy herd using a decision support tool to estimate the net present value (NPV; $/cow per yr) from using the 2 different pregnancy diagnosis methods. The analysis revealed minor differences in NPV between the programs, depending on the cost to perform ULTRA or PALP. In summary, we observed no difference in the reproductive performance and only a minor and fluctuating economic difference when using either PALP or ULTRA for pregnancy diagnosis of dairy cows.     

Evaluation and characterization of estrus alerts and behavioral parameters generated by an ear-attached accelerometer-based system for automated detection of estrus

Our objectives were to evaluate the performance of an ear-attached automated estrus detection (AED) system (Smartbow; Zoetis) that monitored physical activity and rumination time, and to characterize AED system estrus alert features (i.e., timing and duration). Lactating Holstein cows (n = 216) commenced a protocol for the synchronization of estrus at 50 ± 3 DIM or 18 ± 3 d after artificial insemination. For 7 d after induction of luteolysis with PGF_2α (d 0), we used visual observation of estrous behavior (30 min, 2 times per day) and data from an automated mounting behavior monitoring system based on a pressure-activated tail-head sensor (HeatWatch; Cowchips LLC) as a reference test (RTE) to detect behavioral estrus. Concomitantly, estrus alerts and their features were collected from the AED system. Progesterone levels confirmed luteal regression, and transrectal ultrasonography confirmed the occurrence and timing of ovulation. Performance metrics for the AED system were estimated with PROC FREQ in SAS, using the RTE or ovulation only as a reference. Performance was also estimated after the removal of cows with a discrepancy between the RTE and ovulation. Continuous outcomes with or without repeated measurements were evaluated by ANOVA using PROC MIXED in SAS. Based on the RTE, 86.6% (n = 187) of the cows presented estrus and ovulated; 1.4% (n = 3) presented estrus and did not ovulate; 6.4% (n = 14) did not present estrus but ovulated; and 5.6% (n = 12) did not present estrus or ovulation. We found no difference in the proportion of cows detected in estrus and with ovulation for the AED system (83.4%) and the RTE (86.6%). Compared with estrus events as detected by the RTE, sensitivity for the AED was 91.6% (95% CI: 87.6–95.5) and specificity was 69.2% (95% CI: 51.5–87.0). Using ovulation as reference, sensitivity was 89.6% (95% CI: 85.3–93.8) and specificity was 86.7% (95% CI 69.5–100). For all cows with agreement between the RTE and ovulation, sensitivity was 92.5% (95% CI: 88.7–96.3) and specificity was 91.7% (95% CI: 76.0–100). The mean (±SD) interval from induction of luteolysis to estrus alerts, estrus alert duration, and the onset of estrus alerts to ovulation interval were 72.2 ± 18.1, 13.5 ± 3.8, and 23.8 ± 7.1 h, respectively. We concluded that an ear-attached AED system that monitored physical activity and rumination time was effective at detecting cows in estrus and generated few false positive alerts when accounting for ovulation, cow physiological limitations, and the limitations of the RTE.     

Economic performance of lactating dairy cows submitted for first service timed artificial insemination after a voluntary waiting period of 60 or 88 days

The objective of this study was to evaluate the economic performance of dairy cows managed with a voluntary waiting period (VWP) of 60 or 88 d. A secondary objective was estimating variation in cash flow under different input pricing scenarios through stochastic Monte Carlo simulations. Lactating Holstein cows from 3 commercial farms were blocked by parity group and total milk yield in their previous lactation and then randomly assigned to a VWP of 60 (VWP60; n = 1,352) or 88 d (VWP88; n = 1,359). All cows received timed-artificial insemination (TAI) for first service after synchronization of ovulation with the Double-Ovsynch protocol. For second and greater services, cows received artificial insemination (AI) after detection of estrus or the Ovsynch protocol initiated 32 ± 3 d after AI. Two analyses were performed: (1) cash flow per cow for the calving interval of the experimental lactation and (2) cash flow per slot occupied by each cow enrolled in the experiment for an 18-mo period after calving in the experimental lactation. Extending the VWP from 60 to 88 d delayed time to pregnancy during lactation (～20 d) and increased the risk of leaving the herd for multiparous cows (hazard ratio = 1.21). As a result, a smaller proportion of multiparous cows calved again and had a subsequent lactation (?6%). The shift in time to pregnancy combined with the herd exit dynamics resulted in longer lactation length for primiparous (22 d) but not multiparous cows. Longer lactations led to greater milk income over feed cost and a tendency for greater cash flow during the experimental lactation for primiparous but not multiparous cows in the VWP88 group. On the other hand, profitability per slot for the 18-mo period was numerically greater ($68 slot/18 mo) for primiparous cows but numerically reduced (?$85 slot/18 mo) for multiparous cows in the VWP88 treatment. For primiparous cows most of the difference in cash flow was explained by replacement cost, whereas for multiparous cows it was mostly explained by differences in replacement cost and income over feed cost. Under variable input pricing conditions generated through stochastic simulations, the longer VWP treatment always increased cash flow per 18 mo for primiparous and reduced cash flow for multiparous cows. In conclusion, extending the duration of the VWP from 60 to 88 d numerically increased profitability of primiparous cows and reduced profitability of multiparous cows. Such an effect depended mostly on the herd replacement dynamics and milk production efficiency.