Energy efficiency of an outdoor microalgal photobioreactor sited at mid-temperate latitude

This work examined the energetic performance of a 6-month semi-continuous cultivation of Scenedesmus obliquus in an outdoor photobioreactor at mid-temperate latitude, without temperature control. By measuring the seasonal biomass production (mean 11.31, range 1.39-23.67 g m⁻² d⁻¹), higher heating value (22.94 kJ g⁻¹) and solar irradiance, the mean seasonally-averaged photosynthetic efficiency (2.18%) and gross energy productivity (0.27 MJ m⁻² d⁻¹) was calculated. When comparing the solar energy conversion efficiency to the energy investment for culture circulation, significant improvements in reactor energy input must be made to make the system viable. Using the data collected to model the energetic performance of a substitute photobioreactor design, we conclude that sustainable photobioreactor cultivation of microalgae in similar temperate climates requires a short light path and low power input, only reasonably obtained by flat-panel systems. However, temperature control was not necessary for effective long-term cultivation.     

Perspectives on engineering strategies for improving biofuel production from microalgae — A critical review

Although the potential for biofuel production from microalgae via photosynthesis has been intensively investigated, information on the selection of a suitable operation strategy for microalgae-based biofuel production is lacking. Many published reports describe competitive strains and optimal culture conditions for use in biofuel production; however, the major impediment to further improvements is the absence of effective engineering strategies for microalgae cultivation and biofuel production. This comprehensive review discusses recent advances in understanding the effects of major environmental stresses and the characteristics of various engineering operation strategies on the production of biofuels (mainly biodiesel and bioethanol) using microalgae. The performances of microalgae-based biofuel-producing systems under various environmental stresses (i.e., irradiance, temperature, pH, nitrogen depletion, and salinity) and cultivation strategies (i.e., fed-batch, semi-continuous, continuous, two-stage, and salinity-gradient) are compared. The reasons for variations in performance and the underlying theories of the various production strategies are also critically discussed. The aim of this review is to provide useful information to facilitate development of innovative and feasible operation technologies for effectively increasing the commercial viability of microalgae-based biofuel production.     

Perspectives on microalgal CO2-emission mitigation systems — A review

The problem of climate change arising mainly from CO₂ emission is currently a critical environmental issue. Biofixation using microalgae has recently become an attractive approach to CO₂ capture and recycling with additional benefits of downstream utilization and applications of the resulting microalgal biomass. This review summarizes the history and strategies of microalgal mitigation of CO₂ emissions, photobioreactor systems used to cultivate microalgae for CO₂ fixation, current microalgae harvesting methods, as well as applications of valuable by-products. It is of importance to select appropriate microalgal species to achieve an efficient and economically feasible CO₂-emission mitigation process. The desired microalgae species should have a high growth rate, high CO₂ fixation ability, low contamination risk, low operation cost, be easy to harvest and rich in valuable components in their biomass.     

Assessment of a dry and a wet route for the production of biofuels from microalgae: energy balance analysis

In this study, the energy balance of two microalgae-to-biofuel concepts, one via a so called “dry route” (oil extraction from dried algae) and one via a “wet route” (oil extraction in the water phase), are assessed. Both routes are intended to convert the chemical energy contained in the microalgae into high-value biofuels with minimal fossil energy consumption. The analysis shows that the drying process in the dry route and the oil extraction process in the wet route consume a significant amount of energy. By coupling waste heat from a nearby power plant to the process, the energy balance can be improved and a potential fossil energy ratio (FER) up to 2.38 and 1.82 can be reached for the dry and wet route, respectively. The results indicate that based on current available technologies, the dry route has higher FER and the wet route has more potential in producing high valuable biofuels.     

A further look at the 1858 Wallace–Darwin mail delivery question

Recent investigations have led to a conclusion that Alfred Russel Wallace probably mailed his ‘Ternate’ paper on natural selection to Darwin 1 month later than some have assumed, thus freeing Darwin from possible accusations of plagiarism. Further examination of the question suggests that this conclusion is premature because the evidence in favour of the later mailing date appears to be weaker than first considered. © 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, ●● , ●●–●●.     

COVID-19 under spotlight: A close look at the origin,transmission, diagnosis,and treatment of the 2019-nCoV disease

Months after the outbreak of a new flu-like disease in China, the entire world is now in a state of caution. The subsequent less-anticipated propagation of the novel coronavirus disease, formally known as COVID-19, not only made it to headlines by an overwhelmingly high transmission rate and fatality reports, but also raised an alarm for the medical community all around the globe. Since the causative agent, SARS-CoV-2, is a recently discovered species, there is no specific medicine for downright treatment of the infection. This has led to an unprecedented societal fear of the newly born disease, adding a psychological aspect to the physical manifestation of the virus. Herein, the COVID-19 structure, epidemiology, pathogenesis, etiology, diagnosis, and therapy have been reviewed.     

A closer look at the “Protopithecus” fossil assemblages: new genus and species from Bahia,Brazil

The recently extinct large-bodied New World monkey Protopithecus brasiliensis Lund 1836 was named based on a distal humerus and proximal femur found in the Lagoa Santa cave system in the southeastern Brazilian state of Minas Gerais. These bones are from an animal about twice the size of the largest extant platyrrhines. One hundred and seventy-five years later, a nearly complete skeleton was discovered in the Toca da Boa Vista caves in the neighboring state of Bahia and was allocated to the same taxon as it was the first platyrrhine fossil of comparable size found since the originals. Our detailed study of the equivalent elements, however, reveals important morphological differences that do not correspond to intraspecific variation as we know it in related platyrrhine taxa. The presence of both an expanded brachioradialis flange on the humerus and gluteal tuberosity on the femur of the Bahian skeleton distinguishes it from the Lagoa Santa fossil as well as from all other platyrrhines. Further cranial and postcranial evidence suggests a closer relationship of the former with the alouattine Alouatta, while the limited Lund material fits more comfortably with the ateline clade. Therefore, we propose to limit P. brasiliensis Lund to the distal humerus and proximal femur from Lagoa Santa and erect a new genus and species for the skeleton from Toca da Boa Vista. Cartelles coimbrafilhoi was a large-bodied frugivore with a relatively small brain and diverse locomotor repertoire including both suspension and climbing that expands the range of platyrrhine biodiversity beyond the dimensions of the living neotropical primates.     

A new look at evolution in the Galápagos: evidence from the late Cenozoic marine molluscan fauna

Endemism is not as common in the marine invertebrate fauna of the Galápagos Islands region as in the adjacent terrestrial biota. Marine invertebrates in the Galápagos are largely cosmopolitan species from the Panamic, Indo-Pacific, Californian, or Peruvian faunal provinces. However, an endemic component is also present in the fauna. The observed pattern among marine invertebrate organisms can be accounted for by at least two processes: (1) genetic continuity between mainland and island populations mediated through planktonic larvae; and (2) lower rates of intrinsic evolutionary change. The evolutionary scenario standardly applied to terrestrial organisms in the Galápagos, namely, adaptive radiation and speciation in reproductive isolation from mainland source populations, does not apply to all marine invertebrates. Evidence in support of the alternative scenario for marine invertebrates comes from both published records of species occurring in the islands and recent studies of fossil-bearing deposits on several islands in the archipelago. Two misconceptions–considering the islands and sedimentary deposits to be older than now thought, and equating the rate of evolution of the terrestrial biota with the marine biota–can lead to an incorrect interpretation of evolution in the Galápagos Contrasts between marine invertebrate and terrestrial organisms serve to illustrate some fundamental differences which have important evolutionary implications. Some of these are: endemism; dispersal; taxonomic relationships; island definitions; rates of evolutionary change; and age of fossils. In terms of Darwin's evolutionary scenario, terrestrial organisms represent the paradigm and marine organisms represent the paradox.     

Molecularly imprinted polymers—A closer look at the control polymer used in determining the imprinting effect: A mini review

Molecular recognition displayed by naturally occurring receptors has continued to inspire new innovations aimed at developing systems that can mimic this natural phenomenon. Since 1930s, a technology called molecular imprinting for producing biomimetic receptors has been in place. In this technology, tailor made binding sites that selectively bind a given target analyte (also called template) are incorporated in a polymer matrix by polymerizing functional monomers and cross‐linking monomers around a target analyte followed by removal of the analyte to leave behind cavities specific to the analyte. The success of the imprinting process is defined by two main figures of merit, that is, the imprinting factor, and selectivity, which are determined by comparing the amount of target analyte or structural analogue bound by the molecularly imprinted polymer (MIP) and the nonimprinted polymer (NIP). NIP is a control synthesized alongside the MIP but in the absence of the template. However, questions arise on whether these figures of merit are reliable measures of the imprinting effect because of the significant differences between the MIP and the NIP in terms of their physical and chemical characteristics. Therefore, this review critically looks into this subject, with a view of defining the best approaches for determining the imprinting effect.     

A commentary on ‘Mineral soil carbon fluxes in forests and implications for carbon balance assessments’: a deeper look at the data

Forestry practitioners contacted us with their concerns about a recent review article by Buchholz T, Friedland AJ, Hornig CE, Keeton WS, Zanchi G, Nunery J (2013) GCB Bioenergy who questioned the way soil carbon is treated in many models and protocols, and indicated that an increasing number of research studies showed meaningful soil organic carbon (SOC) loss as a result of forest management. We revisit the major studies cited in the review and present a more complete look at the results, consistently treat forest floor carbon as a separate pool, discuss differences in interpretation, and suggest opportunities to advance the state of knowledge regarding SOC and forest carbon accounting. Overall, we conclude that the literature continues to support the current default assumption of little or no change in mineral SOC when sound forest management practices are followed.     

DNA sequence analysis of spontaneous and γ-radiation (anoxic)-induced lacI mutations in Escherichia coliumuC122::Tn5: differential requirement for umuC at G · C vs. A · T sites and for the production of transversions vs. transitions

Escherihica coliumC122::Tn5 cells were γ-radiated (¹³⁷Cs, 750 Gy, under N₂), and lac-constitutive mutants were produced at 36% of the wild-type level (the umC strain was not deficient in spontaneous mutagenesis, and the mutational spectrum determined by sequencing 263 spontaneous lacI^d mutations was very similar to that for the wild-type strain). The specific nature of the umC strain's partial radiation was determined by sequencing 325 radiation-induced lacI^d mutations. The yields of radiation-induced mutation classes in the umC strain (as a percentage of the wild-type yield) were: 80% for A · T → G · C transitions, 70% for multi-base additions, 60% for single-base deletions, 53% for A · T → C · G transversions, 36% for G · C → A · T transitions, 25% for multi-base deletions, 21% for A · T → T · A transversions, 11% for G · C → C · G transversions, 9% for G · C → T · A transversions and 0% for multiple mutations. Based on these deficiencies and other factors, it is concluded that the umC strain is near-normal for A · T → G · C transitions, single-base deletions and possibly A · T → C · G transversions; is generally deficient for mutagenesis at G · C sites fro transversions, and is grossly deficient in multiple mutations. Damage at G · C sites seems more difficult for translesion DNA synthesis to bypass than damage at A · T sites, and especially when trying to produced a transversion. The yield of G · C → A · T transitions in the umC strain *36% of the wild-type level) argues that a basic sites are involved in no more than 64% of γ-radiation-induced base substitutions in the wild-type strain. Altogether, these data suggest that the UmuC and UmuD′ proteins facilitate, rather than being absolutely required for, translesion DNA synthesis; with the degree of facilitation being dependent both on the nature of the noncoding DNA damage, i.e., at G · C vs A · T sites, and on the nature of the misincorporated base, i.e., whether it induces transversions or transitions.