Charge Optimization in Window Air Conditioner with Commercial LPG (Hydrocarbon Blend)

In this paper, the window air conditioner performance with commercial LPG as a replacement of HFC134a is assessed with modified capillary lengths for charge optimization. Global Warming Potential (GWP) of commercial LPG is only three, which is neglected compared to HFC134a (1300). Flammability issues will also be reduced in charge optimization and adopting safety standards. Initially, baseline tests are conducted with HFC134a and commercial LPG in the existing system, and optimum refrigerant charge is determined. The simulation study is conducted with modified capillary lengths for charge reduction of commercial LPG. Experimental assessment is conducted for the charge optimization as per IS 1349 (Part 1) for low ambient test conditions (Domestic Test-DT and Export Test A-ETA) and high ambient test conditions (Export Test B-ETB). With the optimized capillary length and optimum charge quantity, 0.4–2.03% higher cooling capacity, 0.62–8.9% lesser power consumption, and 10.49–16.4% higher COP are achieved with commercial LPG than that of HFC134a baseline at low and high ambient test conditions, respectively.

Sequential Ion-Ion Reactions for Enhanced Gas-Phase Sequencing of Large Intact Proteins in a Tribrid Orbitrap Mass Spectrometer

We are submitting a manuscript describing the application of proton transfer charge reduction to increase the sequence coverage for proteins > 30 kDa using Orbitrap FTMS.

Sequential Ion-Ion Reactions for Enhanced Gas-Phase Sequencing of Large Intact Proteins in a Tribrid Orbitrap Mass Spectrometer

We are submitting a manuscript describing the application of proton transfer charge reduction to increase the sequence coverage for proteins > 30 kDa using Orbitrap FTMS.

Surface-Induced Dissociation of Anionic vs Cationic Native-like Protein Complexes

<p>Characterizing protein-protein interactions, stoichiometries, and subunit connectivity is key to understanding how subunits assemble in biologically relevant multi-subunit protein complexes. Native mass spectrometry (nMS) has emerged as a powerful tool to study protein complexes due to its low sample requirements and tolerance for heterogeneity. For such nMS studies, positive mode ionization is routinely used and charge reduction, through the addition of solution additives, is often used, as the resulting lower charge states are often more compact and considered more native like. When studied with surface-induced dissociation, charge reduced complexes often give increased structural information over their “normal-charged” counter parts. A disadvantage of charge-reduction is that increased adduction, and hence peak broadening, is often observed when charge-reducing solution additives are present. Recent studies have shown that protein complexes ionized using negative mode generally form in lower charge states relative to positive mode. Here we demonstrate that the lower charged protein complex anions, activated by SID in an ultrahigh mass range Orbitrap mass spectrometer, fragment in a manner consistent with their solved structure, hence providing substructural information. Negative mode ionization in ammonium acetate offers the advantage of charge reduction without the peak broadening associated with solution phase charge reduction additives and provides direct structural information, when coupled with SID. </p>

Surface-Induced Dissociation of Anionic vs Cationic Native-like Protein Complexes

<p>Characterizing protein-protein interactions, stoichiometries, and subunit connectivity is key to understanding how subunits assemble in biologically relevant multi-subunit protein complexes. Native mass spectrometry (nMS) has emerged as a powerful tool to study protein complexes due to its low sample requirements and tolerance for heterogeneity. For such nMS studies, positive mode ionization is routinely used and charge reduction, through the addition of solution additives, is often used, as the resulting lower charge states are often more compact and considered more native like. When studied with surface-induced dissociation, charge reduced complexes often give increased structural information over their “normal-charged” counter parts. A disadvantage of charge-reduction is that increased adduction, and hence peak broadening, is often observed when charge-reducing solution additives are present. Recent studies have shown that protein complexes ionized using negative mode generally form in lower charge states relative to positive mode. Here we demonstrate that the lower charged protein complex anions, activated by SID in an ultrahigh mass range Orbitrap mass spectrometer, fragment in a manner consistent with their solved structure, hence providing substructural information. Negative mode ionization in ammonium acetate offers the advantage of charge reduction without the peak broadening associated with solution phase charge reduction additives and provides direct structural information, when coupled with SID. </p>