Piezoelectric materials are widely referred to as "smart" materials because they can transduce mechanical pressure acting on them to electrical signals and vice versa. They are extensively utilized in harvesting mechanical energy from vibrations, human motion, mechanical loads, etc., and converting them into electrical energy for low power devices. Piezoelectric transduction offers high scalability, simple device designs, and high-power densities compared to electro-magnetic/static and triboelectric transducers. This review aims to give a holistic overview of recent developments in piezoelectric nanostructured materials, polymers, polymer nanocomposites, and piezoelectric films for implementation in energy harvesting. The progress in fabrication techniques, morphology, piezoelectric properties, energy harvesting performance, and underpinning fundamental mechanisms for each class of materials, including polymer nanocomposites using conducting, non-conducting, and hybrid fillers are discussed. The emergent application horizon of piezoelectric energy harvesters particularly for wireless devices and self-powered sensors is highlighted, and the current challenges and future prospects are critically discussed.

Aims:  To determine roles of cortex lytic enzymes (CLEs) in Bacillus megaterium spore germination. Methods and Results:  Genes for B. megaterium CLEs CwlJ and SleB were inactivated and effects of loss of one or both on germination were assessed. Loss of CwlJ or SleB did not prevent completion of germination with agents that activate the spore’s germinant receptors, but loss of CwlJ slowed the release of dipicolinic acid (DPA). Loss of both CLEs also did not prevent release of DPA and glutamate during germination with KBr. However, cwlJ sleB spores had decreased viability, and could not complete germination. Loss of CwlJ eliminated spore germination with Ca2+ chelated to DPA (Ca‐DPA), but loss of CwlJ and SleB did not affect DPA release in dodecylamine germination. Conclusions:  CwlJ and SleB play redundant roles in cortex degradation during B. megaterium spore germination, and CwlJ accelerates DPA release and is essential for Ca‐DPA germination. The roles of these CLEs are similar in germination of B. megaterium and Bacillus subtilis spores. Significance and Impact of the Study:  These results indicate that redundant roles of CwlJ and SleB in cortex degradation during germination are similar in spores of Bacillus species; consequently, inhibition of these enzymes will prevent germination of Bacillus spores.

Zinc is essential to a wide range of cellular processes; therefore, it is important to elucidate the molecular mechanisms of zinc homeostasis. To date, no zinc transporters expressed at the enterocyte apical membrane, and so essential to mammalian zinc homeostasis, have been discovered. We identified hZTL1 as a human expressed sequence tag with homology to the basolateral enterocyte zinc transporter ZnT1 and deduced the fulllength cDNA sequence by PCR. The protein of 523 amino acids belongs to the cation diffusion facilitator family of membrane transporters. Unusually, the predicted topology comprises 12 rather than 6 transmembrane domains. ZTL1 mRNA was detected by reverse transcription-PCR in a range of mouse tissues. A Myc-tagged hZTL1 clone was expressed in transiently transfected polarized human intestinal Caco-2 cells at the apical membrane. Expression of hZTL1 mRNA in Caco-2 cells increased with zinc supplementation of the nutrient medium; however, in the placental cell line JAR hZTL1 appeared not to be regulated by zinc. Heterologous expression of hZTL1 in Xenopus laevis oocytes increased zinc uptake across the plasma membrane. The localization, regulatory properties, and function of hZTL1 indicate a role in regulating the absorption of dietary zinc across the apical enterocyte membrane.

Amino acids exert modulatory effects on proteins involved in control of mRNA translation in animal cells through the target of rapamycin (TOR) signaling pathway. Here we use oocytes of Xenopus laevis to investigate mechanisms by which amino acids are "sensed" in animal cells. Small (ϳ48%) but physiologically relevant increases in intracellular but not extracellular total amino acid concentration (or Leu or Trp but not Ala, Glu, or Gln alone) resulted in increased phosphorylation of p70 S6K and its substrate ribosomal protein S6. This response was inhibited by rapamycin, demonstrating that the effects require the TOR pathway. Alcohols of active amino acids substituted for amino acids with lower efficiency. Oocytes were refractory to changes in external amino acid concentration unless surface permeability of the cell to amino acids was increased by overexpression of the System L amino acid transporter. Amino acid-induced, rapamycin-sensitive activation of p70 S6K was conferred when System L-expressing oocytes were incubated in extracellular amino acids, supporting intracellular localization of the putative amino acid sensor. In contrast to lower eukaryotes such as yeast, which possess an extracellular amino acid sensor, our findings provide the first direct evidence for an intracellular location for the putative amino acid sensor in animal cells that signals increased amino acid availability to TOR/p70 S6K .There is growing evidence that nutrients, in particular amino acids (AAs), 1 exert powerful modulatory effects on proteins involved in cell signaling, mRNA translation, and amino acid transport (for review, see Refs. 1-3). Recent studies indicate that signaling pathways responsive to AAs in mammalian cells show a similarity to those that have already been well characterized in lower organisms such as yeast and bacteria (4 -6). The serine-threonine protein kinase mammalian target of rapamycin ((m)TOR) is proposed to act as a "nutrient-dependent gatekeeper" (5) for several cell functions. Two key translational regulators, p70 S6 kinase (p70 S6K ) and eukaryotic initiation factor 4E-binding protein (4E-BP1) lie downstream of (m)TOR in a cell signaling pathway responsive to AA supplementation (7-10). Increased phosphorylation of p70 S6K and 4E-BP1 in response to AA supplementation is inhibited by the immunosuppressant rapamycin, a specific inhibitor of (m)TOR (5, 6). The activation of p70 S6K by phosphorylation enables it to phosphorylate its downstream target ribosomal protein S6 and increase translation of so-called 5Ј-terminal tract of pyrimidines mRNAs, which generally encode ribosomal proteins and elongation factors (2, 11). The activation of p70 S6K is thought to lead to up-regulation of ribosome biosynthesis and thus increase the translational capacity of the cell. Phosphorylation of 4E-BP1 increases protein synthesis by releasing eukaryotic initiation factor 4E, which can then form the eukaryotic initiation factor 4F complex as a prerequisite for translation of the capped mRNAs (reviewed in Ref. 2). Althoug...