Analysis of the mechanical resistance of cement with aggregates of petrous endocarp from macadamia nut

This research evaluates if adding crushed macadamia nutshell to a mixture of cement and sand could result in lighter and more resistant constructive materials. The mechanical resistance under compression of cement blocks made from two different experimental mixtures, in which a certain amount of sand is replaced with crushed nutshell, is compared against two control groups. Results show that blocks made from one of the proposed mixtures got an average resistance around 50% above the controls group while being 3% lighter. Additionally, the physical dependence of the strength of the blocks on the granulometry of the aggregated endocarp fragments, and their percentage to the volume of cement, was studied thanks to contour plots developed from a factorial design of the data.

Chemistry and Functionality of Cold-Pressed Macadamia Nut Oil

The rising trend in the consumption of healthy, safe, and functional foods has motivated studies on cold-pressed specialty oils, including macadamia nut oil. Cold-pressed macadamia nut oil (CPMO) is given preference by consumers over solvent extracted and refined oil because of its exceptional quality attributes and safety. This review contains a detailed presentation of the chemical properties, health benefits, and applications of CPMO. The monounsaturated fatty acids (oleic acid and palmitoleic acid) rich oil also contains a significant concentration of bioactive phytochemicals including, β-sitosterol, α-tocopherol, α-tocotrienols, ρ-hydroxybenzoic acid, and caffeic acid. Moreover, the oil has good oxidative stability. The highlighted properties offer CPMO health benefits related to the prevention of cardiovascular diseases, diabetes, cancer, high blood pressure, and neurodegenerative diseases. The fatty acid composition of CPMO allows for its diverse application in the food, cosmetic, nutraceutical, and pharmaceutical industries.

Macadamia Volatiles Affect the Attraction of the Moth Gymnandrosoma Aurantianum to (E)-8-Dodecenyl Acetate the Main Component of its Sex Pheromone

The macadamia nut borer moth Gymnandrosoma aurantianum, is the main pest of macadamia (Macadamia integrifolia) in Central America. This study investigates the effect of the host (M. integrifolia) on attraction of G. aurantianum to its sex pheromone. Y-Tube bioassays showed that females G. aurantianum were attracted to volatiles from M. integrifolia leaves and flowers, while males responded to volatiles from flowers. Both sexes had significantly different electroantennographic responses (EAG) to the extracts of volatiles from flowers, fruits and leaves and (E)-8-dodecenyl acetate (main component of the sex pheromone of G. aurantianum). Females G. aurantianum exhibited electroantennographic responses by CG-EAD to phenylacetaldehyde, (1Z)-3-methylbutanal oxime and (E)-β-ocimene, while the males showed antennal activity in response to phenylacetaldehyde, (1E)-3-methylbutanal oxime, (1Z)-3-methylbutanal oxime, present in the extracts of M. integrifolia. The EAG dose-response with ocimene (mix of isomers) showed that female antennal activity increases as the dose increases, while with males, the highest dose elicited a response that was significantly different from the control. In field tests, the mixture (ocimene/(E)-8-dodecenyl acetate) with the proportion of 10:1 was the treatment that captured the highest number of males and females. Also, we observed that the lowest number of male captures was obtained with the proportion of 1:1, compared to the traps baited with only (E)-8-dodecenyl acetate. These results suggest that the binary mixture of ocimene plus (E)-8-dodecenyl acetate in a proportion of 10:1 could be an option for monitoring this pest because we obtained captures of both sexes.

Analysis of the Physicochemical Characteristics of Biochar Obtained by Slow Pyrolysis of Nut Shells in a Nitrogen Atmosphere

The process of slow pyrolysis of seven nut shell samples, in a nitrogen-purged atmosphere, has been studied, as well as characteristics of biochar obtained. The heat carrier with a temperature of 400–600 °C (with a step of 100 °C) was supplied indirectly using a double-walled reactor. The heating rate was 60 °C/min. At increased temperature of the heating medium, a decrease in the amount of the resulting carbon residue averaged 6.2 wt%. The release of non-condensable combustible gas-phase compounds CO, CH4, and H2, with maximum concentrations of 12.7, 14.0, and 0.7 vol%, respectively, was registered. The features of the obtained biochar sample conversions were studied using thermal analysis in inert (nitrogen) and oxidative (air) mediums at 10 °C/min heating rate. Kinetic analysis was performed using Coats–Redfern method. Thermal analysis showed that the main weight loss (Δm = 32.8–43.0 wt%) occurs at temperatures ranging between 290 °C and 400 °C, which is due to cellulose decomposition. The maximum carbon content and, hence, heat value were obtained for biochars made from macadamia nut and walnut shells. An increased degree of coalification of the biochar samples affected their reactivity and, in particular, caused an increase in the initial temperature of intense oxidation (on average, by 73 °C). While technical and elemental composition of nut shell samples studied were quite similar, the morphology of obtained biochar was different. The morphology of particles was also observed to change as the heating medium temperature increased, which was expressed in the increased inhomogeneity of particle surface. The activation energy values, for biochar conversion in an inert medium, were found to vary in the range of 10–35 kJ/mol and, in an oxidative medium—50–80 kJ/mol. According to literature data, these values were characteristic for lignin fibers decomposition and oxidation, respectively.

Extracts of Different Organs of Macadamia Nut Tree (Macadamia Integrifolia) Ameliorate Oxidative Damage in D-Galactose Accelerated Aging Model in Rats

Macadamia nut tree, Macadamia integrifolia (Maiden & Betche), is cultivated for the production of the edible macadamia nuts, which are a good source of monounsaturated fatty acids. We investigated the effect of ethanolic extracts of leaves, nuts, and nutshells of macadamia in D-galactose accelerated aging model in rats. Administration of D-galactose (150 mg/kg) in rats for 60 days resulted in impairment of cognitive function and motor coordination and caused an increase in oxidative stress and deterioration of liver and kidney functions. Macadamia nut extract ameliorated cognitive impairment induced by D-galactose as inferred from Morris water maze test and balance test using rotarod. Also, nut extract was superior to leaves and shell extract in reducing serum levels of malondialdehyde (50%), alanine transaminase (63%), aspartate transaminase (63%), total bilirubin (24%), creatinine (38%), and urea (16%) compared to animals that received no treatment. Chemical analysis showed that macadamia nut extract has a high percentage of oleic acid (81%) followed by palmitoleic acid (6.9%). This study encourages further investigation of the health benefits of macadamia nuts and the underlying mechanism of these effects.

First report of ‘Candidatus Phytoplasma asteris’ associated with witches'-broom disease of Macadamia ternifolia in China

Macadamia nut (Macadamia ternifolia) was first introduced into China from Australia in 1910, and the main cultivation areas were Yunnan and Guangxi. It can be used as both a fruit and a therapeutic drug, with high economic value. In March 2021, it was observed that the M. ternifolia was showing witches'-broom, leaf yellowing and plexus bud in Dehong Prefecture, Yunnan Province, China. The terminal buds of infected plants were inhibited and the lateral buds are stimulated to germinate into twigs in advance. It was named the M. ternifolia witches'-broom disease, and was found in urban and rural areas of Mangshi, Lianghe, Yingjiang, Mangdong, Longchuan and Longling cities and counties. More than 40% of the plants were infected on the seven areas surveyed. The lateral stems from symptomatic and asymptomatic plants were cut to small pieces. The tissues were treated by fixation, dehydration and spraying-gold. And the tissues were observed under a scanning electron microscope (Hitachi S-3000N) (Pathan et al. 2010). The nearly spherical bodies were found in the phloem sieve cells of symptomatic plants. Symptomatic and asymptomatic plants were collected from seven areas, ddH2O was used as the negative control, and Dodonaea viscose witches'-broom disease plants were used as the positive control. The total plants’ DNA extraction was conducted from 0.1 g tissue using the CTAB method (Porebski et al. 1997), and were stored at −20 °C in a refrigerator in the Key Laboratory of Forest Disaster Warning and Control at the Southwest Forestry University. The nested PCR was employed to amplify the 16S rRNA gene with the primers P1/P7 and R16F2/R16R2 (Lee et al. 1993; Schneider et al. 1993). PCR amplicon of 1.8 kb and 1.2 kb were amplified (GenBank accessions MW892818, MW892819, MW892820, MW892821). The direct PCR with primer pairs rp(I)F/ rp(I)R (Lee et al. 2003) specific to the ribosomal protein (rp) gene yielded amplicons of approximately 1.2 kb (GenBank accessions MZ442600, MZ442601, MZ442602, MZ442603). The fragment from 21 samples was consistent with the positive control, confirming the association of phytoplasma with the disease. Interestingly, the phytoplasma/span>16S rRNA gene and rp gene was also amplified from the 4 samples of asymptomatic plant, we speculated that the latent infection and hidden symptoms existed in Macadamia nut (Moslemkhani and Sadeghi 2011). A BLAST analysis of the 16S rRNA sequences of MTWB phytoplasma showed that it has a 99% similarity with Trema laevigata witches'-broom phytoplasma (GenBank accession MG755412). The rp sequence shared 99% identity with 'Salix tetradenia' witches'-broom phytoplasma (GenBank accession KC117314). An analysis with iPhyClassifier showed that the virtual RFLP pattern derived from the query 16S rDNA fragment of MTWB phytoplasma is most similar to the reference pattern of the 16Sr group I, subgroup B (OY-M, GenBank accession AP006628), with a pattern similarity coefficient of 0.99. The phytoplasma is identified as ‘Ca. Phytoplasma asteris’-related strain belonging to sub-group 16SrI-B. The phylogenetic tree was constructed based on 16S rRNA gene and rp gene sequences by using MEGA version 6.0 (Tamura et al. 2013) with neighbor-joining (NJ) method and bootstrap support was estimated with 1000 replicates. The result indicated that the MTWB phytoplasma formed a subclade in 16SrI-B and rpI-B respectively. In 2013, Macadamia nut showed leaf hardness phyllody and shoot proliferation caused by ‘Ca. Phytoplasma asteris’ in Artemisa, Cuba. The concern is that, the macadamia phytoplasma is closely related to the subgroup 16SrI-F, and it is significantly different from the Chinese strains (Pérez-López et al. 2013). In addition, the MTWB phytoplasma was graft-transmitted from infected to healthy plants in nursery conditions (Akhtar et al. 2009; Ikten et al. 2014). And the grafted plants were positive for the phytoplasma in the nested PCR assays. It is noteworthy that the plants were seriously damaged by aphid and it was speculated that the insects of Homoptera caused the spread of the disease by sucking plant sap, thus the aphids that transmits MTWB in China must be determined to control the M. ternifolia witches'-broom disease. To the best of our knowledge, Macadamia nut is a new host plant of ‘Ca. Phytoplasma asteris’ in China. The newly emerged disease is a threat to Macadamia nut.