Effets des températures fraîches (5 °C-25 °C) sur la fermentation et l’entreposage d’ensilages de maïs plante entière

L’ensilage est un aliment produit par la fermentation des fourrages sous l’action des bactéries lactiques. Parmi tous les fourrages, le maïs plante entière est une plante importante pour l’alimentation des ruminants et ce, partout dans le monde. Durant la dernière décennie, l’amélioration génétique du maïs a permis d’étendre cette culture toujours plus au nord avec le développement d’hybrides adaptés aux régions plus froides. Plusieurs facteurs influencent le processus de fermentation lors de l’ensilement, dont la température ambiante. L’effet de la température, lorsque celle-ci est inférieure à 20 °C, a été très peu étudié. Considérant ces faits, il devient nécessaire d’étudier l’effet de la température sur le processus d’ensilement du maïs. L’hypothèse émise est que les températures fraîches (5 à 15 °C) affectent le processus d’ensilement du maïs plante entière en diminuant la croissance microbienne, mais aussi en modifiant les populations microbiennes et en particulier les populations de bactéries lactiques épiphytes (BLACE) lors du processus d’ensilement. Ainsi, l’objectif de la présente étude est de déterminer l’effet de la température variant de 5 à 25 °C sur la fermentation et la dynamique des populations microbiennes durant l’entreposage (phase de stabilité anaérobie) de l’ensilage de maïs. Pour étudier ces effets, deux essais ont été réalisés. Avec le premier essai, en utilisant une technique génomique d’évaluation de la diversité microbienne (Chapitre II) de même que les paramètres biochimiques et microbiologiques (Chapitre III), la diversité de la population des BLACE a été suivie pendant 60 jours à cinq températures différentes, variant de 5 à 25 °C. Avec le deuxième essai, le même intervalle de température a été utilisé, mais en simulant une augmentation de température sur des ensilages ayant subi au préalable une fermentation à 10 °C ou à 20 °C, suivi d’un entreposage à 5 °C durant deux mois. La variation des paramètres biochimiques, la composition des populations microbiologiques et la diversité bactérienne (entérobactéries, BLACE) et la population fongique (levures et moisissures) ont été mesurées avec l’augmentation de la température (Chapitre IV). Les résultats du Chapitre II ont démontré que la température exerce une action sélective sur les espèces de BLACE durant le processus d’ensilement. Aux températures les plus élevées (20 et 25 °C), Lactobacillus plantatum, Pediococcus pentosaceus, Lactobacillus brevis, et Lactobacillus buchneri ont été observés durant la fermentation. À ces températures, un changement de fermentation homofermentaire vers une fermentation hétérofermentaire a été observé avec une domination complète de la population de BLACE par le L. buchneri après 60 jours de fermentation. Pour les ensilages incubés à des températures plus froides (5 et 10 °C), Lactobacillus sakei et Lactobacillus curvatus ont dominé la population de BLACE. La température de fermentation des ensilages de maïs à 15 °C indique un point tournant en regard de la diversité des BLACE et de leur succession durant le processus d’ensilement. Au Chapitre III, les résultats ont démontré que les températures les plus froides ont entravé la fermentation ce qui a retardé l’acidification, diminué la vitesse d’acidification, donné un pH final plus élevé, diminué la production d’acides organiques et augmenté les concentrations résiduelles des sucres solubles (SS). Toutefois, les profils fermentaires de ces ensilages ont démontré une fermentation hétérolactique, mais les espèces de BLACE observées par ces profils étaient différentes. Au Chapitre IV, les résultats ont démontré que l’augmentation des températures de 5 à 25 °C n’a pas modifié de façon importante la composition biochimique des ensilages dont le processus d’ensilement a été fait à 20 °C. Toutefois, les dénombrements des levures et des entérobactéries ont démontré des niveaux assez élevés lorsque la température a atteint 15 °C et plus. Par ailleurs, pour les ensilages dont la fermentation a été faite à 10 °C, les résultats ont clairement démontré que la fermentation a démarré de nouveau lorsque la température a dépassé 20 °C. Dans ces ensilages, le L. buchneri a commencé à dominer la population de BLACE. Aucun autre développement microbien n’a été observé comme à 20 °C. Globalement, ces résultats démontrent que la température exerce un effet sélectif sur les espèces de BLACE impliquées dans le processus de fermentation, mais aussi lorsque la température remonte durant l’entreposage. Ces résultats soulèvent la question de l’efficacité des inoculants lactiques présentement vendus sur le marché lorsque les fourrages sont ensilés à des températures inférieures à 20 °C

Energy and Economic Analysis of Life Cycle Zero Energy Building in the Temperate Region

Life cycle zero energy buildings (LCZEBs) can present energy use more accurately than net zero energy buildings (NZEBs). Economic benefits are crucial for residents to accept LCZEBs. However, few relevant case studies have been conducted. A comparative analysis between a NZEB and a LCZEB with a multi-story apartment in a temperate region that meets the requirements of local building energy codes as the reference building was conducted in this study to ascertain economic feasibility of LCZEB. First, a building model and an energy model were established on the basis of site test, survey, and monitoring data. Then, the energy balances of the NZEB and LCZEB were calculated on the basis of the results of energy simulation and the foregoing data. Finally, the LCZEB and NZEB were realized on the condition that high thermal performance materials and high energy efficiency building equipment were adopted in accordance with the principle of maximizing net present value (NPV) and solar energy was fully utilized. Results demonstrate that solar hot water and photovoltaic systems are critical to the NZEB and LCZEB. Annual net energy (ANE) and annual NPV per square meter of thermal collector are −571.11 kWh and $455.5, respectively, and ANE and annual NPV per square meter of photovoltaic panel are −115.62 kWh and$13.2. The NZEB and LCZEB are economically feasible in the temperate region although the NZEB is superior to the LCZEB in terms of economic benefits. Their NPVs for the calculation period (20 years) are $15369.64 and$4718.77, and their payback periods are 11 and 16 years. This study can provide references for energy and economic optimization of NZEBs and LCZEBs

Nadir CA-125 level as prognosis indicator of high-grade serous ovarian cancer

PURPOSE: The capacity of nadir CA-125 levels to predict the prognosis of epithelial ovarian cancer remains controversial. This study aimed to explore whether the nadir CA-125 serum levels could predict the durations of overall survival (OS) and progression free survival (PFS) in patients with high-grade serous ovarian cancer (HG-SOC) from the USA and PRC. MATERIALS AND METHODS: A total of 616 HG-SOC patients from the MD Anderson Cancer Center (MDACC, USA) between 1990 and 2011 were retrospectively analyzed. The results of 262 cases from the Jiangsu Institute of Cancer Research (JICR, PRC) between 1992 and 2011 were used to validate the MDACC data. The CA-125 immunohistochemistry assay was performed on 280 tissue specimens. The Cox proportional hazards model and the log-rank test were used to assess the associations between the clinicopathological characteristics and duration of survival. RESULTS: The nadir CA-125 level was an independent predictor of OS and PFS (p < 0.01 for both) in the MDACC patients. Lower nadir CA-125 levels (≤10 U/mL) were associated with longer OS and PFS (median: 61.2 and 16.8 months with 95% CI: 52.0–72.4 and 14.0–19.6 months, respectively) than their counterparts with shorter OS and PFS (median: 49.2 and 10.5 months with 95% CI: 41.7–56.7 and 6.9–14.1 months, respectively). The nadir CA-125 levels in JICR patients were similarly independent when predicting the OS and PFS (p < 0.01 for both). Nadir CA-125 levels less than or equal to 10 U/mL were associated with longer OS and PFS (median: 59.9 and 15.5 months with 95% CI: 49.7–70.1 and 10.6–20.4 months, respectively), as compared with those more than 10 U/mL (median: 42.0 and 9.0 months with 95% CI: 34.4–49.7 and 6.6–11.2 months, respectively). Baseline serum CA-125 levels, but not the CA-125 expression in tissues, were associated with the OS and PFS of HG-SOC patients in the MDACC and JICR groups. However, these values were not independent. Nadir CA-125 levels were not associated with the tumor burden based on second-look surgery (p = 0.09). Patients who achieved a pathologic complete response had longer OS and PFS (median: 73.7 and 20.7 months with 95% CI: 63.7–83.7 and 9.5–31.9 months, respectively) than those with residual tumors (median: 34.6 and 10.6 months with 95% CI: 6.9–62.3 and 4.9–16.3 months, respectively). CONCLUSIONS: The nadir CA-125 level was an independent predictor of OS and PFS in HG-SOC patients. Further prospective studies are required to clinically optimize the chances for a complete clinical response of HG-SOC cases with higher CA-125 levels (>10 U/mL) at the end of primary treatment

Epicardial calcineurin-NFAT signals through Smad2 to direct coronary smooth muscle cell and arterial wall development

AIMS: Congenital coronary artery anomalies produce serious events that include syncope, arrhythmias, myocardial infarction, or sudden death. Studying the mechanism of coronary development will contribute to the understanding of the disease and help design new diagnostic or therapeutic strategies. Here, we characterized a new calcineurin-NFAT signalling which specifically functions in the epicardium to regulate the development of smooth muscle wall of the coronary arteries. METHODS AND RESULTS: Using tissue-specific gene deletion, we found that calcineurin-NFAT signals in the embryonic epicardium to direct coronary smooth muscle cell development. The smooth muscle wall of coronary arteries fails to mature in mice with epicardial deletion of calcineurin B1 (Cnb1), and accordingly these mutant mice develop cardiac dysfunction with reduced exercise capacity. Inhibition of calcineurin at various developmental windows shows that calcineurin-NFAT signals within a narrow time window at embryonic Day 12.5-13.5 to regulate coronary smooth muscle cell development. Within the epicardium, NFAT transcriptionally activates the expression of Smad2, whose gene product is critical for transducing transforming growth factor β (TGFβ)-Alk5 signalling to control coronary development. CONCLUSION: Our findings demonstrate new spatiotemporal and molecular actions of calcineurin-NFAT that dictate coronary arterial wall development and a new mechanism by which calcineurin-NFAT integrates with TGFβ signalling during embryonic development

Advantages of GaN Based Light-Emitting Diodes with a P-InGaN Hole Reservoir Layer

A p-type InGaN hole reservoir layer (HRL) was designed and incorporated in GaN based light-emitting diodes (LEDs) to enhance hole injection efficiency and alleviate efficiency droop. The fabricated LEDs with p-type HRL exhibited higher light output power, smaller emission energy shift and broadening as compared to its counterpart. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the alleviated band bending in the last couple of quantum well and electron blocking layer, and thus better hole injection efficiency. Meanwhile, the efficiency droop can be effectively mitigated when the p-InGaN HRL was used

Microwave‐Assisted Pyrolysis of Biomass for Bio‐Oil Production

Microwave‐assisted pyrolysis (MAP) is a new thermochemical process that converts biomass to bio‐oil. Compared with the conventional electrical heating pyrolysis, MAP is more rapid, efficient, selective, controllable, and flexible. This chapter provides an up‐to‐date knowledge of bio‐oil production from microwave‐assisted pyrolysis of biomass. The chemical, physical, and energy properties of bio‐oils obtained from microwave‐assisted pyrolysis of biomass are described in comparison with those from conventional pyrolysis, the characteristics of microwave‐assisted pyrolysis as affected by biomass feedstock properties, microwave heating operations, use of exogenous microwave absorbents, and catalysts are discussed. With the advantages it offers and the further research and development recommended, microwave‐assisted pyrolysis has a bright future in production of bio‐oils that can effectively narrow the energy gap and reduce negative environmental impacts of our energy production and application practice

Alkali extraction and physicochemical characterization of hemicelluloses from young bamboo (Phyllostachys pubescens Mazel)

Two hemicellulose fractions were obtained by extraction of one-month- old young bamboo (Phyllostachys pubescens Mazel). The fractionation procedure employed 2% NaOH as extractant, followed by filtration, acidification, precipitation, and washing with 70% ethanol solution. The total yield was 26.2%, based on the pentosan content in bamboo. The physicochemical properties were determined and sugar composition analysis showed that the hemicelluloses consisted mainly of xylose, arabinose, galactose, and a small amount of uronic acid. Furthermore, based on FT-IR and NMR spectra analyses, the structure of hemicelluloses was determined to be mainly arabinoxylans linked via (1→4)-β-glycosidic bonds with branches of arabinose and 4-O-methyl-D-glucuronic acid. The molecular weights were 6387 Da and 4076 Da, corresponding to the hemicelluloses HA and HB. Finally, the thermal stability was elucidated using the TG-DTG method. The obtained results can provide important information for understanding young bamboo and the hemicelluloses in it