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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Speed of Sound Measurements of Binary Mixtures of Hydrofluorocarbons [Pentafluoroethane (R-125), 1,1-Difluoroethane (R-152a), or 1,1,1,2,3,3,3-Heptafluoropropane (R-227ea)] with Hydrofluoroolefins [2,3,3,3-Tetrafluoropropene (R-1234yf) or trans-1,3,3,3-Tetrafluoropropene (R-1234ze(E))]

In this article, speed of sound data measured using a dual-path pulse-echo instrument are reported for three binary refrigerant mixtures, R-125/1234yf, R-1234yf/152a, and R-1234ze(E)/227ea, at compositions of (0.33/0.67) and (0.67/0.33) mole fraction. The speed of sound was studied at temperatures ranging from 230 K to 345 K from pressures slightly above the bubble point curve up to 20 MPa for the mixtures containing R-1234yf and 49 MPa for the R-1234ze(E)/227ea mixtures. The relative combined expanded speed of sound uncertainty ranged from 0.039 % to 0.317 % with a mean uncertainty over all state points of less than 0.10 %. The reported data are compared to the most recent mixture models in REFPROP for each blend studied. Comparisons of available mixture models for the R-125/1234yf and R-1234yf/152a blends exhibit average absolute deviation values ranging from 0.10 % to 0.27 %, and the average absolute deviations for R-1234ze(E)/227ea blends range from 0.62 % to 0.94 %. The comparisons show that only minor adjustments are required to the R-125/1234yf and R-1234yf/152a mixture models to represent the speed of sound data within its uncertainty. However, significant adjustments are needed to improve the current mixture models for the R-1234ze(E)/227ea blend. Deficiencies with the R-1234ze(E)/227ea mixture model are not unexpected since it (1) utilizes a pure-fluid EOS R-1234ze(E) that has been shown to inaccurately represent R-1234ze(E) speed of sound values and (2) uses binary interaction parameters for the chemically similar mixture of R-1234yf/227ea.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Vapor and Liquid ( p –ρ– T–x ) Measurements of Binary Refrigerant Blends Containing R-32, R-152a, R-227ea, R-1234yf, and R-1234ze(E)

In this article, The pressure–density–temperature–composition (p–ρ–T–x) data of binary refrigerant mixtures containing R-32 (difluoromethane), R-152a (1,1,-difluoroethane), R-227ea (1,1,1,2,3,3,3-heptafluoropropane), R-1234yf (2,3,3,3-tetrafluoropropene), and R-1234ze(E) (trans-1,3,3,3-tetrafluoropropene) were measured in both the vapor and liquid phases using a two-sinker, magnetic suspension densimeter. The specific samples in this study comprised two compositions of approximately (0.3/0.7) and (0.7/0.3) mole fraction for each of the following four binary refrigerant blends: R-32 + R-1234yf, R-32 + R-1234ze(E), R-1234yf + R-152a, and R-1234ze(E) + R-227ea. Single-phase vapor densities were measured over a temperature range of approximately 253 to 293 K and pressures from 0.05 to 0.98 MPa. Single-phase liquid and supercritical densities were measured over a temperature range of approximately 230 to 400 K and pressures up to 22 MPa; for refrigerant blends containing R-1234yf, the maximum pressure was limited to 14 MPa. Overall relative combined, expanded (k = 2) uncertainties in density ranged from 0.025 to 0.191%, with an average uncertainty of approximately 0.05%. Here, we present measurement results, along with comparisons to available literature data and to default equations of state and mixture models included in REFPROP.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Mechanistic Pathways for N 2 O Elimination from trans -R 3 Sn-O-N=N-O-SnR 3 and for Reversible Binding of CO 2 to R 3 Sn-O-SnR 3 (R = Ph, Cy)

The rate and mechanism of the elimination of N 2 O from trans-R 3 Sn-O-N=N-O-SnR 3 (R = Ph ( 1 Ph ) and R = Cy ( 1 Cy )) to form R 3 Sn-O-SnR 3 (R = Ph ( 2 Ph ) and R = Cy ( 2 Cy )) have been studied using both NMR and IR techniques to monitor the reactions in the temperature range of 39–79 °C in C 6 D 6 . Activation parameters for this reaction are ΔH ‡ = 15.8 ± 2.0 kcal·mol –1 and ΔS ‡ = –28.5 ± 5 cal·mol –1 ·K –1 for 1 Ph and ΔH ‡ = 22.7 ± 2.5 kcal·mol –1 and ΔS ‡ = –12.4 ± 6 cal·mol –1 ·K –1 for 1 Cy . Addition of O 2 , CO 2 , N 2 O, or PPh 3 to sealed tube NMR experiments did not alter in a detectable way the rate or product distribution of the reactions. Computational DFT studies of elimination of hyponitrite from trans-Me 3 Sn-O-N=N-O-SnMe 3 ( 1 Me ) yield a mechanism involving initial migration of the R 3 Sn group from O to N passing through a marginally stable intermediate product and subsequent N 2 O elimination. Reactions of 1 Ph with protic acids HX are rapid and lead to formation of R 3 SnX and trans-H 2 N 2 O 2 . Reaction of 1 Ph with the metal radical •Cr(CO) 3 C 5 Me 5 at low concentrations results in rapid evolution of N 2 O. At higher •Cr(CO) 3 C 5 Me 5 concentrations, evolution of CO 2 rather than N 2 O is observed. Addition of 1 atm or less CO 2 to benzene or toluene solutions of 2 Ph and 2 Cy resulted in very rapid reaction to form the corresponding carbonates R 3 Sn-O-C(=O)-O-SnR 3 (R = Ph ( 3 Ph ) and R = Cy ( 3 Cy )) at room temperature. Evacuation results in fast loss of bound CO 2 and regeneration of 2 Ph and 2 Cy . Variable temperature data for formation of 3 Cy yield ΔH o = –8.7 ± 0.6 kcal·mol –1 , ΔS o = –17.1 ± 2.0 cal·mol –1 ·K –1 , and ΔG o 298K = –3.6 ± 1.2 kcal·mol –1 . Furthermore, DFT studies were performed and provide additional insight into the energetics and mechanisms for the reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Speed of Sound Measurements of Binary Mixtures of Difluoromethane (R-32) with 2,3,3,3-Tetrafluoropropene (R-1234yf) or trans-1,3,3,3-Tetrafluoropropene (R-1234ze(E)) Refrigerants

In this article, sound speed data measured using a dual-path pulse-echo instrument are reported for binary mixtures of difluoromethane (R-32) with 2,3,3,3-tetrafluoropropene (R-1234yf) or trans-1,3,3,3-tetrafluoropropene (R-1234ze(E)). The sound speed is reported at two compositions for each binary mixture of approximately (0.33/67) and (0.67/0.33) mole fraction at temperatures between 230 K and 345 K. Data are reported from pressures slightly above the bubble point to 12 MPa for R-32/1234yf mixtures to avoid potential polymerization reactions and to 53 MPa for the R-32/1234ze(E) mixtures. The mean uncertainty of the sound speed data are less than 0.1% of the measured value where uncertainties at individual state points range from 0.04% to 0.5% of the measured value as the conditions approach the mixture critical region. The reported data are compared to available Helmholtz-energy-explicit EOS included in REFPROP and all systems studied have average absolute deviations greater than 2%. The comparisons show that further adjustments to the mixture models are needed to provide a reasonable representation of the data within its experimental uncertainty.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Bubble Point Measurements of Three Binary Mixtures of Refrigerants: R-32/1234yf, R-32/1234ze(E), and R-1132a/1234yf

In this article, bubble point pressures of three binary mixtures at two compositions each have been measured utilizing a static method. The mixtures studied were difluoromethane + 2,3,3,3-tetrafluoroprop-1-ene (R-32/1234yf), difluoromethane + (E)-1,3,3,3-tetrafluoroprop-1-ene (R-32/1234ze(E)), and 1,1-difluoroethene + 2,3,3,3-tetrafluoroprop-1-ene (R-1132a/1234yf). For all of the mixtures, the minimum temperature measured was 270 K. The maximum temperatures measured for the R-32/1234ze(E), R-32/1234yf, and R-1132a/1234yf mixtures were 360, 345, and 325 K, respectively. A total of 100 bubble point pressures are reported and compared to available literature data relative to the REFPROP database. Lemmon, E. W. [ NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP, 10.0; National Institute of Standards and Technology, Standard Reference Data Program: Gaithersburg, 2018]. Additionally, the bubble point pressures obtained in this study are modeled using the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state. The PC-SAFT model parameters, as well as deviations of this work and literature data from the model, are reported.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Tensor hypercontracted ppRPA: Reducing the cost of the particle-particle random phase approximation from O(r {sup 6}) to O(r {sup 4})

In recent years, interest in the random-phase approximation (RPA) has grown rapidly. At the same time, tensor hypercontraction has emerged as an intriguing method to reduce the computational cost of electronic structure algorithms. In this paper, we combine the particle-particle random phase approximation with tensor hypercontraction to produce the tensor-hypercontracted particle-particle RPA (THC-ppRPA) algorithm. Unlike previous implementations of ppRPA which scale as O(r{sup 6}), the THC-ppRPA algorithm scales asymptotically as only O(r{sup 4}), albeit with a much larger prefactor than the traditional algorithm. We apply THC-ppRPA to several model systems and show that it yields the same results as traditional ppRPA to within mH accuracy. Our method opens the door to the development of post-Kohn Sham functionals based on ppRPA without the excessive asymptotic cost of traditional ppRPA implementations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Mixture Model for Refrigerant Pairs R-32/1234yf, R-32/1234ze(E), R-1234ze(E)/227ea, R-1234yf/152a, and R-125/1234yf

In this work, thermodynamic models based on the corresponding states framework with departure terms are developed for the refrigerant pairs R-32/1234yf, R-32/1234ze(E), R-1234ze(E)/227ea, R-1234yf/152a, and R-125/1234yf. These models are based on new measurements of density, speed of sound, and phase equilibria, combined with the data available in the literature. The model for R-32/1234yf is most comprehensive in its data coverage, with speed of sound deviations within 1%, density deviations within 0.1%, and bubble- and dew-point pressure deviations within 1%. In conclusion, the other mixtures have generally more limited data availability but a similar goodness of fit.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Expanding the Chemistry of Actinide Metallocene Bromides. Synthesis, Properties and Molecular Structures of the Tetravalent and Trivalent Uranium Bromide Complexes: (C 5 Me 4 R) 2 UBr 2 , (C 5 Me 4 R) 2 U(O-2,6- i Pr 2 C 6 H 3 )(Br), and [K(THF)][(C 5 Me 4 R) 2 UBr 2 ] (R = Me, Et)

The organometallic uranium species (C 5 Me 4 R) 2 UBr 2 (R = Me, Et) were obtained by treating their chloride analogues (C 5 Me 4 R) 2 UCl 2 (R = Me, Et) with Me 3 SiBr. Treatment of (C 5 Me 4 R) 2 UCl 2 and (C 5 Me 4 R) 2 UBr 2 (R = Me, Et) with K(O-2,6- i Pr 2 C 6 H 3 ) afforded the halide aryloxide mixed-ligand complexes (C 5 Me 4 R) 2 U(O-2,6- i Pr 2 C 6 H 3 )(X) (R = Me, Et; X = Cl, Br). Complexes (C 5 Me 4 R) 2 U(O-2,6- i Pr 2 C 6 H 3 )(Br) (R = Me, Et) can also be synthesized by treating (C 5 Me 4 R) 2 U(O-2,6- i Pr 2 C 6 H 3 )(Cl) (R = Me, Et) with Me 3 SiBr, respectively. Reduction of (C 5 Me 4 R) 2 UCl 2 and (C 5 Me 4 R) 2 UBr 2 (R = Me, Et) with KC 8 led to isolation of uranium(III) “ate” species [K(THF)][(C 5 Me 5 ) 2 UX 2 ] (X = Cl, Br) and [K(THF) 0.5 ][(C 5 Me 4 Et) 2 UX 2 ] (X = Cl, Br), which can be converted to the neutral complexes (C 5 Me 4 R) 2 U[N(SiMe 3 ) 2 ] (R = Me, Et). Analyses by nuclear magnetic resonance spectroscopy, X-ray crystallography, and elemental analysis are also presented.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Nanostructured crystals of fluorite phases Sr{sub 1−x}R{sub x}F{sub 2+x} (R Are Rare Earth Elements) and their ordering: 10. Ordering under spontaneous crystallization and annealing of Sr{sub 1−x}R{sub x}F{sub 2+x} Alloys (R = Tb-Lu, Y) with 23.8–36.1 mol % RF{sub 3}

The products of spontaneous crystallization (at a cooling rate of ∼200 K/min) of Sr{sub 1−x}R{sub x}F{sub 2+x} melts in the homogeneity range of the fluorite phase have been investigated. Thirty-two irrational compositions with 23.8–36.1 mol % RF{sub 3} and eight rational Sr{sub 2}RF{sub 7} compositions are obtained. With respect to the RF{sub 3} content, these compositions form five groups: (1) Sr{sub 0.762}R{sub 0.238}F{sub 2.238} (23.8% RF{sub 3}), (2) Sr{sub 0.744}R{sub 0.256}F{sub 2.256} (25.6%), (3) Sr{sub 0.718}R{sub 0.282}F{sub 2.282} (28.2%), (4) Sr{sub 2}RF{sub 7} (33.3%), and (5) Sr{sub 0.639}R{sub 0.361}F{sub 2.361} (36.1%). R = Tb-Lu, Y for all groups. Quenching melts of group 5 with R = Tb, Dy, and Ho leads to the formation of ordered phases with the trigonal distortion of the rhβ-Na{sub 7}Zr{sub 6}F{sub 31} type, while for melts of group 5 with R = Lu, quenching yields a phase of the trigonal rhα′-Sr{sub 4}Lu{sub 3}F{sub 17} type. In group 5 with R = Y, Er, Tm, or Yb and in groups 1–4 with all REEs, fluorite phases are formed. Annealing at 900 ± 20°C for 96 h with subsequent cooling at a rate of ∼200 K/min expands the variety of ordered phases: a phase with a new r type of orthorhombic distortion is formed in group 1 with R = Lu, in group 2 with R = Tm or Lu, and in group 3 with R = Ho-Lu, Y; a t-Sr{sub 2}RF{sub 7} phase with tetragonal distortion is formed in group 4 with R = Tb-Er, Y; and a phase of trigonal rhα′ type is formed in group 5 with R = Y, Yb, or Lu. A fluorite phase arises in group 1 with R = Tb-Lu, Y as a result of quenching and annealing. The tendency to ordering becomes more pronounced with an increase in the RF{sub 3} content and REE atomic number. The annealing conditions do not provide equilibrium or the completely ordered state of all alloys.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

New series of triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) with framework structures and mobile silver ion sublattices

Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized and single crystals of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were grown. In their structures, the MoO{sub 4} tetrahedra, pairs and trimers of edge-shared (Mg, R)O{sub 6} octahedra are connected by common vertices to form a 3D framework. Large framework cavities involve Ag{sup +} cations disordered on three nearby positions with CN=3+1 or 4+1. Alternating (Mg, R)O{sub 6} octahedra and MoO{sub 4} tetrahedra in the framework form quadrangular windows penetrable for Ag{sup +} at elevated temperatures. Above 653–673 K, the newly obtained molybdates demonstrate abrupt reduction of the activation energy to 0.4–0.6 eV. At 773 K, AgMg{sub 3}Al(MoO{sub 4}){sub 5} shows electric conductivity 2.5·10{sup −2} S/cm and E{sub a}=0.39 eV compatible with characteristics of the best ionic conductors of the NASICON type. - Graphical abstract: Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized, AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were structurally characterized, ion-conductive properties of AgMg{sub 3}Al(MoO{sub 4}){sub 5} were measured. Display Omitted - Highlights: • Triple molybdates AgA{sub 3}R(MoO{sub 4}){sub 5} (A=Mg, R=Cr, Fe; A=Mn, R=Al, Cr, Fe, Sc, In) of the NaMg{sub 3}In(MoO{sub 4}){sub 5} type were synthesized. • Single crystals of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) were grown and their crystal structures were determined. • Disordering Ag{sup +} ions and penetrable framework structures of AgMg{sub 3}R(MoO{sub 4}){sub 5} (R=Cr, Fe) suggest 2D-character of silver-ion mobility. • Measured ion-conductive properties of AgMg{sub 3}Al(MoO{sub 4}){sub 5} are compatible with characteristics of the best ionic conductors of the NASICON type.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2012

R{sub 4}Ir{sub 13}Ge{sub 9} (R=La, Ce, Pr, Nd, Sm) and RIr{sub 3}Ge{sub 2} (R=La, Ce, Pr, Nd): Crystal structures with nets of Ir atoms

The crystal structures of the new ternary compounds Sm{sub 4}Ir{sub 13}Ge{sub 9} and LaIr{sub 3}Ge{sub 2} were determined and refined on the basis of single-crystal X-ray diffraction data. They belong to the Ho{sub 4}Ir{sub 13}Ge{sub 9} (oP52, Pmmn) and CeCo{sub 3}B{sub 2} (hP5, P6/mmm) structure types, respectively. The formation of isotypic compounds R{sub 4}Ir{sub 13}Ge{sub 9} with R=La, Ce, Pr, Nd, and RIr{sub 3}Ge{sub 2} with R=Ce, Pr, Nd, was established by powder X-ray diffraction. The RIr{sub 3}Ge{sub 2} (R=La, Ce, Pr, Nd) compounds exist only in as-cast samples and decompose during annealing at 800 Degree-Sign C with the formation of R{sub 4}Ir{sub 13}Ge{sub 9}. The structure of Sm{sub 4}Ir{sub 13}Ge{sub 9} contains intersecting, slightly puckered nets of Ir atoms (4{sup 4})(4{sup 3}.6){sub 2}(4.6{sup 2}){sub 2} and (4{sup 4}){sub 2}(4{sup 3}.6){sub 4}(4.6{sup 2}){sub 2} that are perpendicular to [0 1 1] as well as to [0 -1 1] and [0 0 1]. The Ir atoms are surrounded by Ge atoms that form tetrahedra or square pyramids (where the layers intersect). The Sm and additional Ir atoms (in trigonal-planar coordination) are situated in channels along [1 0 0] (short translation vector). In the structure of LaIr{sub 3}Ge{sub 2} the Ir atoms form planar Kagome nets (3.6.3.6) perpendicular to [0 0 1]. These nets alternate along the short translation vector with layers of La and Ge atoms. - Graphical abstract: The crystal structures contain the nets of Ir atoms as main structural motif: R{sub 4}Ir{sub 13}Ge{sub 9} contains intersecting slightly puckered nets of Ir atoms, whereas in the structure of RIr{sub 3}Ge{sub 2} the Ir atoms form planar Kagome nets. Highlights: Black-Right-Pointing-Pointer The Ir-rich ternary germanides R{sub 4}Ir{sub 13}Ge{sub 9} (R=La, Ce, Pr, Nd, Sm) and RIr{sub 3}Ge{sub 2} (R=La, Ce, Pr, Nd) have been synthesized. Black-Right-Pointing-Pointer The RIr{sub 3}Ge{sub 2} compounds exist only in as-cast samples and decompose during annealing at 800 Degree-Sign C with the formation of R{sub 4}Ir{sub 13}Ge{sub 9}. Black-Right-Pointing-Pointer The structure of R{sub 4}Ir{sub 13}Ge{sub 9} contains intersecting slightly puckered nets of Ir atoms. Black-Right-Pointing-Pointer In the structure of RIr{sub 3}Ge{sub 2} the Ir atoms form planar Kagome nets.

36 MATERIALS SCIENCE↗
DOE OSTI2022

The R -process Alliance: A Nearly Complete R -process Abundance Template Derived from Ultraviolet Spectroscopy of the R -process-enhanced Metal-poor Star HD 222925 *

We present a nearly complete rapid neutron-capture process (r-process) chemical inventory of the metal-poor ([Fe/H] = -1.46 ± 0.10) r-process-enhanced ([Eu/Fe] = +1.32 ± 0.08) halo star HD 222925. This abundance set is the most complete for any object beyond the solar system, with a total of 63 metals detected and seven with upper limits. It comprises 42 elements from 31 ≤ Z ≤ 90, including elements rarely detected in r-process-enhanced stars, such as Ga, Ge, As, Se, Cd, In, Sn, Sb, Te, W, Re, Os, Ir, Pt, and Au. We derive these abundances from an analysis of 404 absorption lines in ultraviolet spectra collected using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope and previously analyzed optical spectra. A series of appendices discusses the atomic data and quality of fits for these lines. The r-process elements from Ba to Pb, including all elements at the third r-process peak, exhibit remarkable agreement with the solar r-process residuals, with a standard deviation of the differences of only 0.08 dex (17%). In contrast, deviations among the lighter elements from Ga to Te span nearly 1.4 dex, and they show distinct trends from Ga to Se, Nb through Cd, and In through Te. The r-process contribution to Ga, Ge, and As is small, and Se is the lightest element whose production is dominated by the r-process. The lanthanide fraction, log X La = -1.39 ± 0.09, is typical for r-process-enhanced stars and higher than that of the kilonova from the GW170817 neutron-star merger event. We advocate adopting this pattern as an alternative to the solar r-process-element residuals when confronting future theoretical models of heavy-element nucleosynthesis with observations.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Crystallization of lysozyme with (R)-, (S)- and (RS)-2-methyl-2, 4-pentanediol

Crystallization of lysozyme with (R)-2-methyl-2, 4-pentanediol produces more ordered crystals and a higher resolution protein structure than crystallization with (S)-2-methyl-2, 4-pentanediol. The results suggest that chiral interactions with chiral additives are important in protein crystal formation. Chiral control of crystallization has ample precedent in the small-molecule world, but relatively little is known about the role of chirality in protein crystallization. In this study, lysozyme was crystallized in the presence of the chiral additive 2-methyl-2, 4-pentanediol (MPD) separately using the R and S enantiomers as well as with a racemic RS mixture. Crystals grown with (R)-MPD had the most order and produced the highest resolution protein structures. This result is consistent with the observation that in the crystals grown with (R)-MPD and (RS)-MPD the crystal contacts are made by (R)-MPD, demonstrating that there is preferential interaction between lysozyme and this enantiomer. These findings suggest that chiral interactions are important in protein crystallization.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗