HLB

A wide variety of surfactants are available in market therefore one must need to choose suitable surfactant to give maximum effect to final product. Hydrophilic-lipophilic balance (HLB) system enables to choose proper surfactant with ease. Therefore, study of HLB system is very important. This paper reviews the importance of HLB system and methods of calculating it. Further, it also provides the distinction of surfactants application based on their HLB values. This paper would be useful to get easy access to calculations of HLB and would act as a time-saving guide to surfactant selection.

Huanglongbing (HLB) es considerada mundialmente como la enfermedad más amenazadora para la citricultura, y ha impactado principalmente en Asia, Sudáfrica y Brasil. A la fecha, no se cuenta con un tratamiento efectivo para la detección de esta enfermedad, que pueda ayudar a disminuir su propagación y la consecuente eliminación de árboles infectados. El método más confiable hasta ahora, para la identificación del HLB, es la prueba de reacción en cadena de la polimerasa (qrt-PCR), la cual es costosa y tardada. Esta es la primera revisión de los diferentes métodos existentes o en desarrollo para la detección e identificación del HLB; clasificados en métodos de análisis y reconocimiento de patrones en imágenes, espectrofotométricos, cromatográficos y moleculares a través del insecto vector. Algunos de estos métodos representan alternativas innovadoras con diferente nivel de eficiencia en tiempo, costo y confiabilidad en la detección de árboles enfermos de HLB o en el manejo de la enfermedad, con relación a los tradicionalmente utilizados.

Volatile organic compounds (VOC) play an important role in protecting plants from insect and pathogen attack. In this study, we investigated the leaf volatile profiles of 14 citrus varieties. The VOC in citrus leaves were extracted with n-hexane and analyzed using gas chromatography-mass spectrometry (GC-MS). Overall, 4six volatile compounds were identified in the n-hexane extract from citrus leaves. Most of the detected compounds belonged to 3 main groups (monoterpenes, sesquiterpenes, and aliphatic aldehydes). Principle component analysis was used to examine the relative distribution of the studied varieties to each other. Interestingly, volatile profiles of varieties that are tolerant to Candidatus Liberibacter asiaticus (CLas) were different from those of the susceptible ones. Tolerant and moderately tolerant cultivars contained relatively higher amounts of volatiles than susceptible varieties. In addition, tolerant varieties were also higher in specific compounds which are known for their antimicrobial activities. These compounds include Aldehydes (undecanal, neral, geranial, and citronellal) and some monoterpenes such as linalool, d-limonene, myrcene, a- and b- phellandrene. In addition, some sesquiterpene compounds including t-caryophellene, g-elemene, b-elemene, germacrene D, and geranyl acetate were higher in tolerant and moderately tolerant cultivars. Severinia buxifolia which is known for its tolerance to CLas and many other pathogens contained higher levels of santalenes and coumarins. Our results indicated that citrus leaf volatiles might play a role in citrus tolerance to CLas. The results of this study may help in understanding of the mechanism of citrus tolerance against CLas.

Huanglongbing (HLB) is presently the most devastating citrus disease worldwide. As an intracellular plant pathogen and insect symbiont, the HLB bacterium, 'Candidatus Liberibacter asiaticus' (Las), retains the entire flagellum-encoding gene cluster in its significantly reduced genome. Las encodes a flagellin and hook-associated protein (Fla) of 452 amino acids that contains a conserved 22 amino acid domain (flg22) at positions 29 to 50 in the N-terminus. The phenotypic alteration in motility of a Sinorhizobium meliloti mutant lacking the fla genes was partially restored by constitutive expression of Fla(Las). Agrobacterium-mediated transient expression in planta revealed that Fla(Las) induced cell death and callose deposition in Nicotiana benthamiana, and that the transcription of BAK1 and SGT1, which are associated with plant innate immunity, was upregulated. Amino acid substitution experiments revealed that residues 38 (serine) and 39 (aspartate) of Fla(Las) were essential...

Citrus greening or huanglongbing (HLB) is the main threat to the european citrus industry since one of its vectors, the African citrus psyllid, Trioza erytreae, has recently become established in mainland europe. In this context, classical biological control programmes should be implemented to reduce the spread of the psyllid. the aims of this study were to: i) disentangle the parasitoid complex of T. erytreae combining morphological and molecular characterization; and ii) to study the biology of its main parasitoids in its area of origin in south Africa for their future importation into europe. the main citrus producing areas of South Africa were surveyed during 2017. In contrast to previous studies, the parasitoid complex of T. erytreae included three species of primary parasitoids: Tamarixia dryi, Psyllaephagus pulvinatus and another parasitoid of the genus Tamarixia. Molecular analysis showed that it is a new species closely related to T. dryi. Tamarixia dryi was the most abundant parasitoid but its relative abundance varied among sampling sites. the sex ratio (males/females) of T. dryi and Tamarixia sp. decreased with T. erytreae size and became female biased when psyllid nymphs were larger than 0.6 and 1.2 mm 2 , respectively. these parasitoids were attacked by three species of hyperparasitoids, Aphidencyrtus cassatus, Marietta javensis and a species of the genus Aphanogmus. Aphidencyrtus cassatus, the most abundant hyperparasitoid, tended to emerge from large nymphs, and adult females lived as long as those of T. dryi. the implications of these results are discussed within the framework of the introduction of T. dryi into europe.

The aim of this study was to find out the thermal and environmental performance of a four-stroke, single-cylinder, direct injection 10-kW CI engine at varying engine load conditions using different test fuels. The formulated fuels, viz. CeO2 nanoparticles-dispersed water-diesel-biodiesel fuel blend (CNWEDB) and water-diesel-biodiesel fuel blend (WEDB), were prepared using emulsification technique using CeO 2 nanoparticles and water as additives in diesel-biodiesel blend (B20). The measured fuel properties of CNWEDB and WEDB satisfied the criteria of Indian Standard for biodiesel indicating their suitability for use in CI engine. The engine was run at various loads (0, 20, 40, 60, 80 and 100%) randomly to assess its thermal and environmental performance with all test fuels. Thermal performance of CI engine was evaluated by measuring the parameters such as brake thermal efficiency (BTE), brake-specific fuel consumption (bsfc), exhaust gas temperature (EGT) and heat balance for all test fuels. The environmental performance of engine was assessed by measuring CO, HC and NOx emissions for all test fuels. Adding water and CeO2 nanoparticles into B20 improved BTE of engine by 7.65% over diesel. Also, the minimum heat losses were observed at 80% engine load for CNWEDB indicating a better conversion of fuel energy to useful work. EGT and bsfc of engine reduced with CNWEDB over WEDB and B20 fuels. Engine fueling with CNWEDB emitted 12.82%, 14.46% and 14.20%; and 30.77%, 43.67% and 26.80% lesser concentration of CO, HC and NOx emissions over WEDB and diesel, respectively.

El estado de Colima se le conoce como el principal productor de limón. En 2010 se detectó la presencia del Huanglonbing (HLB), enfermedad de los brotes amarillos en esta región, misma que ha ocasiona-do pérdidas progresivas. Hasta el momento no se conoce cura y la baja rentabilidad de la producción provoca que el agricultor decida retirar la plantación. Así, la reconversión productiva, implica modifi-car el patrón de producción, mediante el establecimiento de cultivos alternativos con mayor viabilidad agronómica, social y rentabilidad económica. El objetivo de este trabajo fue cuantificar los cambios en los cultivos, además de valorar el potencial de las nuevas plantaciones. Para monitorear, identificar y cuantificar los cambios; se recurrió al análisis de imágenes de satélite, formación y análisis de bases de datos agrícolas, entrevistas y mediciones en campo. Entre otros se comprobó un progresivo aumento en el reemplazo de cultivos, se han sustituido alrededor de 5 000 ha de cítricos, lo que ha significado una reducción de 84,721 ton en el volumen de producción del limón mexicano y una pérdida de 302,636,729 de pesos aproximadamente. La superficie de cultivos emergentes como papaya y piña va en aumento y han representado mayores ingresos económicos para los productores.

Several heterocyclic derivatives were evaluated experimentally to
determine their physical properties and antimicrobial activity. Then these
compounds were tested with Marvinsketch program to determine their
protonation, geometry, charge, and partitioning. Partitioning characters
(log P and log D at pI) were calculated by Consensus and Chemaxon
methods while HLB was with Chemaxon and Davies methods. For
example, the derivatives of EDTA based structure showed that isoelectric
point (pI) did not affected by the presence of negative charge compared
with its zero charge. As is expected, negative charge, presence of sulfur
atoms, and type of heterocyclic moiety had a good influence on HLB
values. The obtained results confirmed high harmonization between the
experimental and computerized calculations especially when several of
them where tested against Staphylococcus aureus, Bacillus subtilus,
Escherichia coli, Pseudomonas aeruginosa, and Candida albicans.

LH: lower highlands LM: lower midlands MA: monoclonal antibodies UM: upper mislands This study was undertaken to characterize the alpha subgroup of the proteobacteria causing the huanglongbing (HLB) disease of citrus from three different ecological zones of Kenya namely the Lower highlands (LH2, LH3, 1800-1900 m above sea level);

Huanglongbing (HLB) is the most destructive, yet incurable disease of citrus. Finding sources of genetic resistance to HLB-associated 'Candidatus Liberibacter asiaticus' (Las) becomes strategic to warrant crop sustainability, but no resistant Citrus genotypes exist. Some Citrus relatives of the family Rutaceae, subfamily Aurantioideae, were described as full-resistant to Las, but they are phylogenetically far, thus incompatible with Citrus. Partial resistance was indicated for certain cross-compatible types. Moreover, other genotypes from subtribe Citrinae, sexually incompatible but graftcompatible with Citrus, may provide new rootstocks able to restrict bacterial titer in the canopy. Use of seedlings from monoembryonic species and inconsistencies in previous reports likely due to Las recalcitrance encouraged us to evaluate more accurately these Citrus relatives. We tested for Las resistance a diverse collection of graft-compatible Citrinae species using an aggressive and consistent challengeinoculation and evaluation procedure. Most Citrinae species examined were either susceptible or partially resistant to Las. However, Eremocitrus glauca and Papua/New Guinea Microcitrus species as well as their hybrids and those with Citrus arose here for the first time as full-resistant, opening the way for using these underutilized genotypes as Las resistance sources in breeding programs or attempting using them directly as possible new Las-resistant Citrus rootstocks or interstocks.

A study was conducted for fuel characterization of a stable nano-oxide added water emulsified biodiesel blend (NWEB) prepared with optimal emulsifying parameters. NWEB prepared with Hydrophilic-lipophilic balance (HLB) value 5.0 indicated the least separation from emulsion layer as compared to other HLB values 4.3 and 6.0. Fourier transformed infrared spectroscopy was conducted in Mid-IR range to ensure the quality of biodiesel and emulsified fuel. The stability data of NWEB prepared with varying the emulsifying parameters were used in radial basis function neural network (RBFNN) for simulation of actual and predicted separation from emulsion. The well trained RBFNN model was coupled with particle swarm optimization (PSO) technique to find the optimal emulsifying parameters to produce a stable NWEB. The predicted optimal emulsifying parameters were found as 69.7 ppm nano-oxide concentration, 10% water, 1% surfactant and 2500 rpm of stirrer for a predicted separation of 0.90% after 30 h of emulsification against actual separation of 0.84%. The fuel properties of NWEB and base fuels were determined following the standard procedures. These properties were found within the limits of American, European and Indian Standards for diesel, biodiesel and biodiesel blends and thus indicating the suitability of these fuels in diesel engine.

An experimental study was conducted to investigate the combustion behaviour of a constant speed, 5.5 kW, 4-stroke, single-cylinder, water cooled, direct injection (DI) diesel engine fueled with water emulsified diesel. Water emulsified diesel prepared with 20% water/diesel ratio, 0.9% surfactant amount at 2200 rpm of stirrer with hydrophile-lipophile balance (HLB) value 4.3 was checked for fuel properties. The cylinder gas pressure (CGP) was higher in water emulsified diesel as compared to diesel for similar engine loading. The peak CGP was found to be 95.86 and 95.18 bar for water emulsified diesel and diesel, respectively at full engine load. At higher engine load, better turbulence of combustible mixture and oxidation of soot particles by OH radicals in water emulsified diesel helped in raising the peak rate of pressure rise. A higher ignition delay was observed in the combustion of water emulsified diesel. Water emulsified diesel exhibited ignition delay of 23, 21, 19, 18 and 17 degree crank angle (°CA) at no load, 25, 50, 75 and 100% load, respectively as compared to 20, 20, 18, 14, and 9°CA with diesel for similar engine loading. The longer ignition delay period in water emulsified diesel helped in burning of more fuel leading to higher instantaneous heat release rate (Qn). At full engine load, its value was found to be 223.06 and 207.90 J/°CA for water emulsified diesel and diesel, respectively.

The African citrus psyllid, Trioza erytreae, vectors citrus greening or huanglongbing (HLB) disease. The psyllid has been reported from mainland Europe, where it is rapidly spreading from the northwest to the southwest of the Iberian Peninsula. In order to reduce its spread and population levels, a classical biological control program with the parasitoid Tamarixia dryi is under development in Spain. We evaluated the host specificity of T. dryi using 11 non-target psyllid (NTP) species, including five species of the genus Trioza. The psyllids were selected based on phylogenetic and ecological criteria. Tamarixia dryi exhibited a high host specificity. Females did not parasitize any of the 11 NTPs tested, except for one nymph of a gall-forming Trioza species closely related to Trioza montanetana. Tamarixia dryi only laid one egg on a nymph when it was removed from the gall on Convolvulus canariensis and exposed directly to the parasitoid. However, the immature parasitoid died before emerging. We further confirmed that T. dryi did not parasitize a representative triozid species, Trioza laurisilvae, of the endemic Canarian fauna after long time exposure. Our results demonstrate that T. dryi is a highly specific parasitoid and its introduction, release and establishment in Europe within the classical biological control program of T. erytreae should not affect other psyllid species. Therefore, no significant environmental impact is expected.

Citrus greening caused by (Candidatus liberibacter spp.) is one of the most destructive bacterial disease of citrus all over the world and it is transmitted by grafting as well as psyllid (Diaphorina citri) is responsible for its spread. This study was aimed to detect the prevalence of CLas in different varieties of citrus in Pakistan and molecular characterization of mtco1 gene in Diaphorina citri. DNA was extracted from fourteen different citrus cultivars infected with citrus greening from different orchards of Sargodha Punjab, Pakistan. Specific primers were used to amplify (Mtco1 gene) in Diaphorina citri and also Las specific primers were also used to detect HLB pathogen. Amplified fragments of 507bp, 1500bp and 2500bp were observed in CLas and Mtco1 gene of Asian isolates. The resulted fragments were TA cloned and sequenced from both strands. The infectious bacterium was found in 3 samples out of 14 (21.5 %) while from psyllid it was found in 5 samples (37.5%). The weather changes effect the prevalence of CLas in citrus but usually it decrease during autumn and found Las positive vector in spring or summer season up to 42 o C. So there is a need to research on management of citrus greening disease in Pakistan as it caused major yield loses.