10 research outputs found
Site-level strategies for managing secondary forests
This chapter sets out the possible management objectives and technical options for managing secondary forests as part of an forest landscape rehabilitation (FLR) program. The two main alternative strategies – managing improved fallows without compromising agricultural production, and managing forests for production or conservation purposes – are discussed, together with the types of conditions that favour one above the other. There is considerable ambiguity and confusion in the current use of the term ‘secondary forest’ both in the literature and in people’s perceptions. The term has been applied to numerous types of forests with different characteristics and arising from many different processes. ITTO (2002) defines it as: woody vegetation regrowing on land that was largely cleared of its original forest cover (ie carried less than 10% of the original forest cover)
Kinetically Controlled Lifetimes in Redox-Responsive Transient Supramolecular Hydrogels
It remains challenging
to program soft materials to show dynamic,
tunable time-dependent properties. In this work, we report a strategy
to design transient supramolecular hydrogels based on kinetic control
of competing reactions. Specifically, the pH-triggered self-assembly
of a redox-active supramolecular gelator, <i>N</i>,<i>N</i>′-dibenzoyl-l-cystine (DBC) in the presence
of a reducing agent, which acts to disassemble the system. The lifetimes
of the transient hydrogels can be tuned simply by pH or reducing agent
concentration. We find through kinetic analysis that gel formation
hinders the ability of the reducing agent and enables longer transient
hydrogel lifetimes than would be predicted. The transient hydrogels
undergo clean cycles, with no kinetically trapped aggregates observed.
As a result, multiple transient hydrogel cycles are demonstrated and
can be predicted. This work contributes to our understanding of designing
transient assemblies with tunable temporal control
A Capped Dipeptide Which Simultaneously Exhibits Gelation and Crystallization Behavior
Short
peptides capped at their N-terminus are often highly efficient
gelators, yet notoriously difficult to crystallize. This is due to
strong unidirectional interactions within fibers, resulting in structure
propagation only along one direction. Here, we synthesize the N-capped
dipeptide, benzimidazole-diphenylalanine, which forms both hydrogels
and single crystals. Even more remarkably, we show using atomic force
microscopy the coexistence of these two distinct phases. We then use
powder X-ray diffraction to investigate whether the single crystal
structure can be extrapolated to the molecular arrangement within
the hydrogel. The results suggest parallel β-sheet arrangement
as the dominant structural motif, challenging existing models for
gelation of short peptides, and providing new directions for the future
rational design of short peptide gelators
A Capped Dipeptide Which Simultaneously Exhibits Gelation and Crystallization Behavior
Short
peptides capped at their N-terminus are often highly efficient
gelators, yet notoriously difficult to crystallize. This is due to
strong unidirectional interactions within fibers, resulting in structure
propagation only along one direction. Here, we synthesize the N-capped
dipeptide, benzimidazole-diphenylalanine, which forms both hydrogels
and single crystals. Even more remarkably, we show using atomic force
microscopy the coexistence of these two distinct phases. We then use
powder X-ray diffraction to investigate whether the single crystal
structure can be extrapolated to the molecular arrangement within
the hydrogel. The results suggest parallel β-sheet arrangement
as the dominant structural motif, challenging existing models for
gelation of short peptides, and providing new directions for the future
rational design of short peptide gelators
L'Auto-vélo : automobilisme, cyclisme, athlétisme, yachting, aérostation, escrime, hippisme / dir. Henri Desgranges
07 avril 19181918/04/07 (A19,N6285)
Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons
The
culturing of primary neurons represents a central pillar of neuroscience
research. Primary neurons are derived directly from brain tissue and
recapitulate key aspects of neuronal development in an in vitro setting.
Unlike neural stem cells, primary neurons do not divide; thus, initial
attachment of cells to a suitable substrate is critical. Commonly
used polylysine substrates can suffer from batch variability owing
to their polymeric nature. Herein, we report the use of chemically
well-defined, self-assembling tetrapeptides as substrates for primary
neuronal culture. These water-soluble peptides assemble into fibers
which facilitate adhesion and development of primary neurons, their
long-term survival (>40 days), synaptic maturation, and electrical
activity. Furthermore, these substrates are permissive toward neuronal
transfection and transduction which, coupled with their uniformity
and reproducible nature, make them suitable for a wide variety of
applications in neuroscience
Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons
The
culturing of primary neurons represents a central pillar of neuroscience
research. Primary neurons are derived directly from brain tissue and
recapitulate key aspects of neuronal development in an in vitro setting.
Unlike neural stem cells, primary neurons do not divide; thus, initial
attachment of cells to a suitable substrate is critical. Commonly
used polylysine substrates can suffer from batch variability owing
to their polymeric nature. Herein, we report the use of chemically
well-defined, self-assembling tetrapeptides as substrates for primary
neuronal culture. These water-soluble peptides assemble into fibers
which facilitate adhesion and development of primary neurons, their
long-term survival (>40 days), synaptic maturation, and electrical
activity. Furthermore, these substrates are permissive toward neuronal
transfection and transduction which, coupled with their uniformity
and reproducible nature, make them suitable for a wide variety of
applications in neuroscience
Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons
The
culturing of primary neurons represents a central pillar of neuroscience
research. Primary neurons are derived directly from brain tissue and
recapitulate key aspects of neuronal development in an in vitro setting.
Unlike neural stem cells, primary neurons do not divide; thus, initial
attachment of cells to a suitable substrate is critical. Commonly
used polylysine substrates can suffer from batch variability owing
to their polymeric nature. Herein, we report the use of chemically
well-defined, self-assembling tetrapeptides as substrates for primary
neuronal culture. These water-soluble peptides assemble into fibers
which facilitate adhesion and development of primary neurons, their
long-term survival (>40 days), synaptic maturation, and electrical
activity. Furthermore, these substrates are permissive toward neuronal
transfection and transduction which, coupled with their uniformity
and reproducible nature, make them suitable for a wide variety of
applications in neuroscience
Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons
The
culturing of primary neurons represents a central pillar of neuroscience
research. Primary neurons are derived directly from brain tissue and
recapitulate key aspects of neuronal development in an in vitro setting.
Unlike neural stem cells, primary neurons do not divide; thus, initial
attachment of cells to a suitable substrate is critical. Commonly
used polylysine substrates can suffer from batch variability owing
to their polymeric nature. Herein, we report the use of chemically
well-defined, self-assembling tetrapeptides as substrates for primary
neuronal culture. These water-soluble peptides assemble into fibers
which facilitate adhesion and development of primary neurons, their
long-term survival (>40 days), synaptic maturation, and electrical
activity. Furthermore, these substrates are permissive toward neuronal
transfection and transduction which, coupled with their uniformity
and reproducible nature, make them suitable for a wide variety of
applications in neuroscience
Peptide Nanofiber Substrates for Long-Term Culturing of Primary Neurons
The
culturing of primary neurons represents a central pillar of neuroscience
research. Primary neurons are derived directly from brain tissue and
recapitulate key aspects of neuronal development in an in vitro setting.
Unlike neural stem cells, primary neurons do not divide; thus, initial
attachment of cells to a suitable substrate is critical. Commonly
used polylysine substrates can suffer from batch variability owing
to their polymeric nature. Herein, we report the use of chemically
well-defined, self-assembling tetrapeptides as substrates for primary
neuronal culture. These water-soluble peptides assemble into fibers
which facilitate adhesion and development of primary neurons, their
long-term survival (>40 days), synaptic maturation, and electrical
activity. Furthermore, these substrates are permissive toward neuronal
transfection and transduction which, coupled with their uniformity
and reproducible nature, make them suitable for a wide variety of
applications in neuroscience