Percussion Ensemble featuring John Wesley Dankwa, Master Drummer from Ghana

Kennesaw State University School of Music presents Percussion Ensemble featuring John Wesley Dankwa, master drummer from Ghana.https://digitalcommons.kennesaw.edu/musicprograms/1364/thumbnail.jp

Potassium and the K\u3csup\u3e+\u3c/sup\u3e/H\u3csup\u3e+\u3c/sup\u3e Exchanger Kha1p Promote Binding of Copper to ApoFet3p Multi-copper Ferroxidase

Acquisition and distribution of metal ions support a number of biological processes. Here we show that respiratory growth of and iron acquisition by the yeast Saccharomyces cerevisiae relies on potassium (K+) compartmentalization to the trans-Golgi network via Kha1p, a K+/H+ exchanger. K+ in the trans-Golgi network facilitates binding of copper to the Fet3p multi-copper ferroxidase. The effect of K+ is not dependent on stable binding with Fet3p or alteration of the characteristics of the secretory pathway. The data suggest that K+ acts as a chemical factor in Fet3p maturation, a role similar to that of cations in folding of nucleic acids. Up-regulation of KHA1 gene in response to iron limitation via iron-specific transcription factors indicates that K+ compartmentalization is linked to cellular iron homeostasis. Our study reveals a novel functional role of K+ in the binding of copper to apoFet3p and identifies a K+/H+ exchanger at the secretory pathway as a new molecular factor associated with iron uptake in yeast

Potassium and the K\u3csup\u3e+\u3c/sup\u3e/H\u3csup\u3e+\u3c/sup\u3e Exchanger Kha1p Promote Binding of Copper to ApoFet3p Multi-copper Ferroxidase

Acquisition and distribution of metal ions support a number of biological processes. Here we show that respiratory growth of and iron acquisition by the yeast Saccharomyces cerevisiae relies on potassium (K+) compartmentalization to the trans-Golgi network via Kha1p, a K+/H+ exchanger. K+ in the trans-Golgi network facilitates binding of copper to the Fet3p multi-copper ferroxidase. The effect of K+ is not dependent on stable binding with Fet3p or alteration of the characteristics of the secretory pathway. The data suggest that K+ acts as a chemical factor in Fet3p maturation, a role similar to that of cations in folding of nucleic acids. Up-regulation of KHA1 gene in response to iron limitation via iron-specific transcription factors indicates that K+ compartmentalization is linked to cellular iron homeostasis. Our study reveals a novel functional role of K+ in the binding of copper to apoFet3p and identifies a K+/H+ exchanger at the secretory pathway as a new molecular factor associated with iron uptake in yeast

Outer-Sphere Contributions to the Electronic Structure of Type Zero Copper Proteins

Bioinorganic canon states that active-site thiolate coordination promotes rapid electron transfer (ET) to and from type 1 copper proteins. In recent work, we have found that copper ET sites in proteins also can be constructed without thiolate ligation (called “type zero” sites). Here we report multifrequency electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and nuclear magnetic resonance (NMR) spectroscopic data together with density functional theory (DFT) and spectroscopy-oriented configuration interaction (SORCI) calculations for type zero Pseudomonas aeruginosa azurin variants. Wild-type (type 1) and type zero copper centers experience virtually identical ligand fields. Moreover, O-donor covalency is enhanced in type zero centers relative that in the C112D (type 2) protein. At the same time, N-donor covalency is reduced in a similar fashion to type 1 centers. QM/MM and SORCI calculations show that the electronic structures of type zero and type 2 are intimately linked to the orientation and coordination mode of the carboxylate ligand, which in turn is influenced by outer-sphere hydrogen bonding

Distortion losses of high speed single-photon avalanche diode receivers approaching quantum sensitivity

Data traffic is growing exponentially, and the radio frequency (RF) spectrum is under pressure to meet these demands. Visible light communication (VLC) has hundreds of terahertz of unused and unregulated bandwidth and the widespread use of solid-state lighting makes it viable to supplement RF networks. Present optical receivers (RXs) use positive-intrinsic-negative (PIN) diodes or avalanche photodiodes (APDs) and amplification circuitry that impairs RX sensitivity. In this work, the extremely high gain of single-photon avalanche diodes (SPADs) is utilised to remove the need for an amplifier. This offers significantly improved sensitivity and allows the quantum limit of detection to be approached. A SPAD array integrated in 40 nm CMOS is used to determine the transient response of SPADs and investigate the effect of dead time after a photon is detected. A 130 nm CMOS SPAD array RX in this work achieves 500 Mb/s four-level pulse amplitude modulation and 350 Mb/s OFDM in a 450 nm laser diode-based VLC link within 15.2 dB of the quantum limit. However, SPAD dead time induces around 5.7 dB of transient distortion which restricts error performance and data rate an order of magnitude below that of APDs. This thesis builds a model of a discrete photon counting system which exhibits this nonlinear behaviour and compares it to practical measurements with the RX. A unipolar intensity-modulated optical signal is considered, as opposed to bipolar electric fields in conventional RF systems. Intermodulation is analysed, and the resulting degradation of signal-to-noise-and-distortion ratio and bit error rate is evaluated. The model is a tool for understanding distortion to ultimately allow rectification through RX architecture, modulation scheme, coding, and equalisation techniques. The thesis concludes that the SPAD RX is effective with very low optical power, allowing considerable improvements of two orders of magnitude in transmitter energy efficiency or one order of magnitude in link distance compared to present VLC systems – useful for underwater applications. This work proves that the high electrical power consumption disadvantage due to the SPAD bias can be alleviated by operating the RX in an optimum region determined in the model. Further savings and integration advantages are gained by using CMOS. This SPAD RX demonstrates the lowest power consumption and highest sensitivity to date. The need for narrow bandpass spectral filtering in bright ambient light conditions remains a limitation of the SPAD RX