Invited review: Large-scale indirect measurements for enteric methane emissions in dairy cattle: A review of proxies and their potential for use in management and breeding decisions

Efforts to reduce the carbon footprint of milk production through selection and management of low-emitting cows require accurate and large-scale measurements of methane (CH₄) emissions from individual cows. Several techniques have been developed to measure CH₄ in a research setting but most are not suitable for large-scale recording on farm. Several groups have explored proxies (i.e., indicators or indirect traits) for CH₄; ideally these should be accurate, inexpensive, and amenable to being recorded individually on a large scale. This review (1) systematically describes the biological basis of current potential CH₄ proxies for dairy cattle; (2) assesses the accuracy and predictive power of single proxies and determines the added value of combining proxies; (3) provides a critical evaluation of the relative merit of the main proxies in terms of their simplicity, cost, accuracy, invasiveness, and throughput; and (4) discusses their suitability as selection traits. The proxies range from simple and low-cost measurements such as body weight and high-throughput milk mid-infrared spectroscopy (MIR) to more challenging measures such as rumen morphology, rumen metabolites, or microbiome profiling. Proxies based on rumen samples are generally poor to moderately accurate predictors of CH₄, and are costly and difficult to measure routinely on-farm. Proxies related to body weight or milk yield and composition, on the other hand, are relatively simple, inexpensive, and high throughput, and are easier to implement in practice. In particular, milk MIR, along with covariates such as lactation stage, are a promising option for prediction of CH₄ emission in dairy cows. No single proxy was found to accurately predict CH₄, and combinations of 2 or more proxies are likely to be a better solution. Combining proxies can increase the accuracy of predictions by 15 to 35%, mainly because different proxies describe independent sources of variation in CH₄ and one proxy can correct for shortcomings in the other(s). The most important applications of CH₄ proxies are in dairy cattle management and breeding for lower environmental impact. When breeding for traits of lower environmental impact, single or multiple proxies can be used as indirect criteria for the breeding objective, but care should be taken to avoid unfavorable correlated responses. Finally, although combinations of proxies appear to provide the most accurate estimates of CH₄, the greatest limitation today is the lack of robustness in their general applicability. Future efforts should therefore be directed toward developing combinations of proxies that are robust and applicable across diverse production systems and environments.     

Structural engineering of hierarchically hetestructured Mo2C/Co conformally embedded in carbon for efficient water splitting

Developing low-cost and high efficient electrocatalysts for both oxygen and hydrogen evolution reaction in an alkaline electrolyte toward overall water splitting is still a significant challenge. Here, a novel hierarchically heterostructured catalyst composed of ultrasmall Mo₂C and metallic Co nanoparticles confined within a carbon layer is produced by a facile phase separation strategy. During thermal reduction of CoMoO₄ nanosheets in CO ambient, in-situ generated nanoscale Co and ultrafine Mo₂C conformally encapsulated in a conductive carbon layer. In addition, some carbon nanotubes catalyzed by Co nanoparticles vertically grew on its surface, creating 3D interconnected electron channels. More importantly, the integrated C@Mo₂C/Co nanosheets assembled into the hierarchical architecture, providing abundant active surface and retaining the structural integrity. Benefiting from such unique structure, the constructed hierarchical heterostructure shows low overpotentials of 280 mV and 145 mV to reach a current density of 10 mA cm⁻² for OER and HER in an alkaline electrolyte. Furthermore, the symmetrical electrolyzer assembled with catalyst exhibits a small cell voltage of 1.67 V at 10 mA cm⁻² in addition to outstanding durability, demonstrating the great potential as a high efficient bifunctional electrocatalyst for overall water splitting.     

HClO对TYR氧化的理论研究

海洋生物黏附引起的生物污损危害极大,其分泌的黏附单元3,4-二羟基苯丙氨酸(多巴,DOPA)具有超强粘性,而DOPA又是由酪氨酸(TYR)氧化而来。导电涂膜电解海水阻断生物黏附是近年来发展的1种新的防污技术,研究电解海水产生的HCLO对贻贝黏附单元DOPA前体酪氨酸(TYR)的修饰机理,可以为探讨HCLO阻断海洋生物黏附技术提供有力的理论依据。采用广义梯度密度泛函理论(GGA)的BLYP方法研究HCLO对TYR修饰的4条主要可行反应路径,经过频率分析这些反应的过渡态构型均只有唯一虚频,所有途径均可阻止酪氨酸(TYR)形成DOPA,降低贻贝的黏附性。计算结果表明反应路径(1)为生成3-氯酪氨酸的主要路径,连续反应(1)(3)是生成3,5-二氯酪氨酸的主要路径。在反应初期,3-氯酪氨酸是主要产物,反应后期,3-氯酪氨酸浓度增加,反应路径(3)同反应路径(1)的竞争性增大,3,5-二氯酪氨酸的浓度明显提高,计算结果也与实验结果吻合。     

超级棕榈液油在湘味面粉熟食冬季生产中的应用

湘味面粉熟食的冬季生产用油大多是一级大豆油,但是其用油成本较高、易哈败、产品货架期较短。本试验在大豆油中加入适量超级棕榈液油和抑晶剂制成调合油,用于生产冬季湘味面粉熟食中,分析比较各自熟食产品的品质及其在0～5℃冬季气温条件下的贮藏稳定性。结果表明,分别利用优化配方调和油和一级大豆油生产的湘味面粉熟食在品质上没有明显差异,均达到DB43/160.8———2009标准的质量要求;而且,调和油熟食的氧化稳定性优于大豆油熟食。说明利用超级棕榈液油部分取代大豆油来生产湘味面粉熟食,不但可以降低生产成本,还可以延长产品货架期。     

Limited enzymatic proteolysis increases the level of incorporation of canola proteins into mayonnaise

An alkaline extract of canola meal was hydrolyzed using a protease (Proleather FG-F) for 2.5 and 10 min to obtain protein hydrolysates with 7% and 14% degree of hydrolysis (DH), respectively. The protein hydrolysates were used to replace up to 50% (w/w) of egg yolk in a model mayonnaise preparation and the effects on physicochemical properties determined. Unhydrolyzed canola proteins could only be incorporated into mayonnaise up to a maximum 15% (w/w) substitution of egg yolk without emulsion breakdown. At 7% DH, the canola protein could be used to substitute up to 20% (w/w) of egg yolk, while at 14% DH the maximum level of substitution was 50% (w/w). Increased level of canola protein products reduced the whiteness and increased the reddish-brown colour of mayonnaise. Mayonnaise that was stabilized by only egg yolk had the least particle size and highest viscosity when compared to emulsions stabilized by canola proteins. Stability studies showed that most of the mayonnaise preparations retained their physicochemical properties after storage for 4 weeks at 4 °C. The results suggest that limited protein hydrolysis can be used to increase the level of incorporation of globular proteins into mayonnaise preparations.Industrial relevanceModifications to the native structures of plant proteins remain a viable industrial option for improving their functionality in food systems. Therefore, the process described in this work could promote utilization of enzymatically modified canola proteins as suitable ingredients in the formulation of food emulsions.     

光皮树籽油功能性作用的研究

为了研究光皮树籽油的辅助降血脂功能,将SD大鼠随机分成4组：空白对照组、高脂对照组、高剂量组、低剂量组,并以高脂饲料建立实验模型。同时又对不同组别大鼠的肝系数及动脉粥样硬化指数AI值进行比较。结果表明：光皮树籽油能显著降低大鼠血清总胆固醇、甘油三酯的水平（p〈0.05）,而对大鼠高密度脂蛋白胆固醇HDL-C水平无显著影响（p〉0.05）。由此可知,光皮树籽油具有降血脂功能,同时还具有一定的预防脂肪肝和防止动脉粥样硬化的作用。     

棕榈油复配物代替猪油用于桃酥制作

比较棕榈油桃酥和猪油桃酥产品的感官品质以及在同等储藏条件下的酸价和过氧化值的变化情况,以判断棕榈油对猪油的可替代性。结果表明:复配棕榈油基起酥油不仅可以达到猪油基起酥油用在桃酥制作上的良好效果,而且棕榈油桃酥具有比猪油桃酥更好的氧化稳定性。本实验为棕榈油基起酥油代替猪油用于桃酥制作提供一定理论依据。     

In-situ crystalline infiltrated Mo2C@C for efficient hydrogen evolution reaction

Molybdenum carbide (Mo₂C) is a promising electrocatalyst for hydrogen evolution reaction (HER) due to the similar electron orbital structure to platinum. Preparing Mo₂C catalyst in nanoscale increases the exposure of active catalyst site and significantly enhances electrochemical reaction and improve HER performance. However, Mo₂C is not a good electron conductor which still requires a more sufficient contact between the catalyst and electrode to transfer electron current. Here, we proposed in-situ Mo₂C growth on carbon nanotubes (CNTs) by using wet impregnation of ammonium molybdate tetrahydrate as Mo source, which established a crystalline transition contact between Mo₂C and CNTs and significantly improved HER performance. Our results further showed the optimized HER performance of Mo₂C@C_amt and achieved a lower Tafel slopes and low onset potential (η_onset) of 46.7 mV dec⁻¹, 51.3 mV dec⁻¹ and 73 mV and 127 mV (vs. RHE) under alkaline and acidic condition, respectively. Furthermore, Mo₂C@C_amt also shows less attenuation after 1000 times of cyclic voltammograms (CV) cycling stability test and 25 h continuous operation under alkaline and acidic condition.     

大豆油调和不同熔点棕榈液油的冷藏试验

为了制备适应不同储存温度的豆油-棕榈液油调和油,以大豆油与不同熔点棕榈液油为原料,采用冷藏试验方法优化抑晶剂种类、用量和调和油配方。结果表明,羟基硬脂精是效果最佳的抑晶剂,其最佳添加量为0.025%;调和油1(豆油70%+10℃棕榈油30% +羟基硬脂精0.025%)在0℃环境下储存可保持16h以上澄清透亮,在5℃条件可保持72h以上澄清透亮;调和油2(豆油70%+18℃棕榈油30%+羟基硬脂精0.025%)在10℃环境下可保持30h以上澄清透亮;调和油3(豆油60%+18℃棕榈油40%+羟基硬脂精0.025%)在15℃环境下可保持20h以上澄清透亮;调和油4(豆油60%+24℃棕榈油40%+羟基硬脂精0.025%)在20℃环境下可保持10h以上澄清透亮。