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Cellulose nanofibrils (CNFs) have been widely used as a nanofiller for polymer composite reinforcement due to their excellent mechanical properties. However, CNF is produced in water and needs to be dried prior to use in composite materials. The presence of hydroxyl groups on the surface of CNF creates strong hydrogen bonding that makes it difficult and costly to dry. Additionally, the hydrophilicity at the fiber surface results in agglomeration of CNFs within many polymer matrices. In this study, chitosan (CS) was co-precipitated with CNF to produce a dual-bonding filler for use in poly (lactic acid) (PLA) composites. CS promotes improved interfacial interaction within the polymer matrix by forming strong hydrogen bonds with the CNF and potential covalent bonds with the PLA. The results confirmed that the addition of a small amount of CS significantly improved the mechanical properties compared to PLA + CNF composites and neat PLA. The detailed study of the PLA + CNF/CS composites reveals the synergetic effect of the hydrogen and covalent bonding mechanism for PLA reinforcement. Graphical abstract

A new genus Holcelmis with 2 new species, H. woodruffi and H. mamore, and a related new genus and species, Epodelmis rosa, are described from the lowlands of Bolivia.

Tyletelmis mila, a new genus and species, is described from Brazil and French Guiana. A new genus, Tolmerelmis, is erected to contain Heterelmis pubipes Hinton of Brazil and Argentina.

Males of the butterfly Eurema lisa, like many other members of the family Pieridae, reflect ultraviolet light. The color is structural rather than pigmentary, and originates from optical interference in a microscopic lamellar system associated with ridges on the outer scales of the wing. The dimensions and angular orientation of the lamellar system conform to predictions based on physical measurement of the spectral characteristics, including \"color shifts\" with varying angles of incidence, of the reflected ultraviolet light. The female lacks such scales and is consequently nonreflectant. The ultraviolet dimorphism supposedly serves as the basis for sexual recognition in courtship.

This paper is concerned to show that the capacity to tolerate a total suspension of metabolism (cryptobiosis) is a primitive characteristic of protoplasm. It is a characteristic that makes it possible to visualize a much wider range of environmental conditions for the possible origin of the first living systems. The characteristics of the cryptobiotic state are first noted, certain special features of cryptobiosis revealed by experiments on complex multicellular animals are then described, and finally the relevance of all this to theories about the origin of life are briefly noted.

Plastron-bearing spiracular gills have been independently evolved in two groups of the Psephenidae, the Psephenoidinae and one genus of the Eubriinae. The spiracular gills of the pupae are exclusively spiracular structures. The plastron is on the spiracle rather than on the body wall adjacent to the spiracle, as in the pupae of flies. In some species the spiracular gills are borne at the end of projections from the body wall. In one genus of Eubriinae, epidermal cells that remain in good condition are isolated in the projections from the body wall in such a way that they are completely separated by a thick wall of cuticle from the remaining tissues of the body in both the pupal stage and in the pharate adult stage. The origin of plastron respiration in the Psephenidae is discussed. Non-aquatic pupae are found near the edges of streams where they are apt to be flooded by rises in stream level. The water/air interface of normal spiracles is too small (400 to 1100 μm2/mg) to satisfy oxygen demands by extracting oxygen from the ambient water when they are flooded. The water/air interface of the least well-developed plastrons in insects is equivalent to about 15000 μm2/mg of body weight. It is suggested that every increase in the length of the spiracles has a selective advantage in that it enables the pupa to utilize atmospheric oxygen when covered by correspondingly thicker layers of water. At some stage in this process, plastron respiration through the spiracles becomes significant in satisfying oxygen demands. When this stage is reached, selective pressures begin to operate directly to increase the water/air interface of the spiracles. It is shown that if all spiracles of some forms, such as Metaeopsephenus, were like its longest spiracles, the linear dimensions of the spiracles would only have to be increased by a factor of 2*2 for these to have a water/air interface per mg of body weight equivalent to that of some insects with plastrons. Spiracles that do not function in gas exchanges between the insect and the ambient environment nevertheless persist because they subserve two other functions: (a) when they are first formed their chambers or ecdysial tubes provide a lumen through which the old tracheae of the previous instar may be withdrawn, and (b) after the appearance of the new instar their chambers, now collapsed, are the means by which the tracheae of the previous instar are anchored to the cuticle that is to be shed. Spiracles that do not function in gas exchanges and have their orifices closed are known as non-functional spiracles. Once a spiracle becomes non-functional in a particular instar it remains non-functional in that instar despite the fact that it is temporarily open between the moult and the ecdysis. The loss of functional spiracles is irreversible irrespective of changes in the habits or environment of the group. Examples of irreversible losses of functional spiracles are cited that concern more than one million cases. In some Psephenidae the spiracles of the first abdominal segment are non-functional. The spiracular atrium and the regulatory apparatus of such spiracles may nevertheless persist and be more or less identical in structure to those of functional spiracles. The evidence suggests that in the subfamily Eubriinae such non-functional structures have persisted since at least the Eocene. Plastron-bearing spiracular gills are polyphyletic in origin. They have been independently evolved at least nine times in the Diptera and twice in the Goleoptera. In the Diptera spiracular gills are modifications of the body wall adjacent to the spiracle (e.g. Tanyderidae, Deuterophlebiidae, and Simuliidae) or of both the body wall and the spiracle (e.g. Tipulidae). In the Coleoptera they are modifications of the spiracle only although the spiracle may be borne on a long projection from the body wall (e.g. Psephenoides volatilis Champ). Because in each group of insects the spiracular gills are independently evolved, a phylogenetic classification of these gills is excluded, but a classification of convenience is proposed.

The spiracular gill is a pupal structure, but it is the chief respiratory organ of the adult of Taphrophila before the pupal cuticle is shed. At the pupa-adult moult, the epidermis and blood in the spiracular gill are completely isolated from the living insect by two cuticles between which is the moulting fluid. A few hours after the isolation of the tissue, the epidermis of most parts of the gill begins to dissociate, the cells become rounded, separate away from the cuticle and from one another, and in due course form loose clumps usually far from the gill walls. The tissue isolated in the gill repairs cuts and tears in the gill walls with a tanned cuticle. At 16 to 18° C the competence of the isolated tissue to repair damage to the gill walls lasts about 14 days. The tissue is isolated 8 to 9 days before the emergence of the adult, and it repairs the gill up to 5 days after the insect has shed it and flown away. The isolated tissue tolerates complete dehydration and high temperatures. In water the isolated tissue of gills previously dried for 70 days over phosphorus pentoxide and heated when dry to 103° C for 2 h, or to 130° C for 30 min, successfully repaired wounds. The epidermis of the adult and larva of Taphrophila also repairs wounds after complete dehydration. The epidermis of other insects is shown to exhibit a similar tolerance to dehydration even when no such tolerance is shown by the insect: the epidermis of some insects that are killed when they lose about 20% of their moisture content will repair wounds after complete dehydration if dried rapidly. The gill of Taphrophila has a plastron that is not wetted at pressures below about 0⋅3 atm above normal pressure, and it is only wetted by surface active substances that reduce the surface tension to about 25 dyn/cm. Apart from its plastron, the gill is not an effective respiratory organ. The gill walls are not rigid. In water, the internal pressure maintains turgidity and maximum surface area necessary for the efficient functioning of the plastron. The internal pressure of intact and unscarred gills is 4⋅3 atm. When the gill is torn or cut open, blood and cells spurt out and there is an immediate equilization of internal and hydrostatic pressures. A clot is rapidly formed at the site of the injury. The increase in the mechanical strength of the clot outpaces the increase in the internal pressure brought about by water that diffuses into the gill. In a number of other Tipulidae beside Taphrophila blood and epiderm is are isolated in the respiratory horn or the spiracular gill at the pupa-adult moult. In some of these, such as the species of Lipsothrix, the epidermis does not dissociate nor separate from the cuticle but becomes syncytial and remains closely attached to the cuticle.