Juan Fernandez de la Mora
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Research Subjects
Juan Fernandez de la Mora has a total of 80 co-authors. Here are the top co-authors by number of shared publications:
- Luis Javier Perez-Lorenzo
Yale University P.O. box 208286, 9 Hillhouse Avenue
11 shared publications Luis J. Perez-Lorenzo
Yale University, Mechanical Engineering Department, PO box 208286, 9 Hillhouse Avenue, New Haven, Connecticut 06511, United States
5 shared publications- Mario Amo-Gonzalez
SEADM, Valladolid, Spain
5 shared publications Michel Attoui
Université Paris Est Créteil, Université Paris Cité, CNRS, LISA
4 shared publicationsChristian Luebbert
Yale University, Mechanical Engineering Department, PO box 208286, 9 Hillhouse Avenue, New Haven, Connecticut 06511, United States
3 shared publications- Juan Fernández-García
Laboratory of Cellular Metabolism and Metabolic Regulation, VIB Center for Cancer Biology, VIB, Leuven, Belgium
3 shared publications
Latest Publications
- 31 October 2026
- Published by American Chemical Society (ACS) in Analytical Chemistry
What Determines the Charge State Distribution of Proteins Electrosprayed from Non-Denaturing Solutions?
The maximum charge on globular electrosprayed protein ions has been rationalized as the maximal charge sustainable by a solvent drop of comparable size, in turn determined by either small ion evaporation or Rayleigh’s limiting charge. Here we show that spontaneous ion evaporation may continue after the protein ion has dried. Multiply charged cations C+z of bovine serum albumin (BSA) or ovalbumin are electrosprayed into dry ambient air from aqueous solutions of ammonium acetate or thriethylammonium formate. A unique dry protein charge state z is isolated (<1 ms) in a first mobility instrument and passed through a parabolic flow tubular reactor (∼200 ms) where dry ion evaporation transitions C+z → C+z−1 → C+z−2... take place. The protein charge state distribution exiting the reactor is then determined (<1 ms) in a second mobility device. All naturally charged BSA+z and ovalbumin+z ions undergo substantial room temperature charge loss within the reactor, both in ammonium acetate and in triethylammonium formate buffers. The observed maximal charge and the charge distribution are therefore determined by the kinetics of dry ion evaporation from the surface of the dry protein, and depend on the residence time, the temperature and the nature of the evaporating ion. The often-observed low charge states characteristic of buffers containing certain amines is due to the weaker binding of these protonated amines to the protein compared to H+ or NH4+. Maximal charge states may hence be obtained from cold sources with short residence times and selected buffers. The dry ion evaporation here observed may not apply to very large proteins.
- 31 October 2026
- Published by American Chemical Society (ACS) in Analytical Chemistry
What Determines the Charge State Distribution of Proteins Electrosprayed from Non-Denaturing Solutions?
The maximum charge on globular electrosprayed protein ions has been rationalized as the maximal charge sustainable by a solvent drop of comparable size, in turn determined by either small ion evaporation or Rayleigh’s limiting charge. Here we show that spontaneous ion evaporation may continue after the protein ion has dried. Multiply charged cations C+z of bovine serum albumin (BSA) or ovalbumin are electrosprayed into dry ambient air from aqueous solutions of ammonium acetate or thriethylammonium formate. A unique dry protein charge state z is isolated (<1 ms) in a first mobility instrument and passed through a parabolic flow tubular reactor (∼200 ms) where dry ion evaporation transitions C+z → C+z−1 → C+z−2... take place. The protein charge state distribution exiting the reactor is then determined (<1 ms) in a second mobility device. All naturally charged BSA+z and ovalbumin+z ions undergo substantial room temperature charge loss within the reactor, both in ammonium acetate and in triethylammonium formate buffers. The observed maximal charge and the charge distribution are therefore determined by the kinetics of dry ion evaporation from the surface of the dry protein, and depend on the residence time, the temperature and the nature of the evaporating ion. The often-observed low charge states characteristic of buffers containing certain amines is due to the weaker binding of these protonated amines to the protein compared to H+ or NH4+. Maximal charge states may hence be obtained from cold sources with short residence times and selected buffers. The dry ion evaporation here observed may not apply to very large proteins.
- 10 February 2026
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 98 (7) , 5284-5291
Tandem Mobility Measurements of Ionic Liquid Cluster Volatilities
We illustrate the potential of a pair of steady-state ion mobility filters run in series, similar to a triple quadrupole mass spectrometer, not only to operate under atmospheric pressure but also to determine reaction kinetics at controlled pressure and temperature. Singly charged cluster cations of the ionic liquid 1-ethyl-3-methyl-imidazolium tris(pentafluoroethyl)trifluorophosphate (EMI-FAP) produced by a bipolar electrospray source are isolated steadily at atmospheric pressure by a first ion mobility spectrometer (IMS). A second IMS then determines the composition of evaporative decay products: (EMI-FAP)n-1EMI+→(EMI-FAP)n-2EMI++EMI-FAP (2 ≤ n ≤ 30) after passing through a heated parabolic flow reactor tube at controlled temperatures T (23-40 °C). Measured product/parent abundance ratios are converted into reaction constants kn via a previously described theory. At n < 11, evaporation rates kn exhibit idiosyncrasies characteristic of various magic numbers, some of which are also reflected in a cluster compactness parameter inferred from the measured mobility cross section and mass. An approximately continuous variation of volatility with n is found for 11 ≤ n ≤ 14, and for n ≥ 19, with a region of low volatility in between. This especially stable domain of four clusters (15 ≤ n ≤ 18) is reached on the right (n = 18) with a discontinuous (4-fold) volatility decrease, suggesting a transition to a liquid-like structure. On the left it merges continuously (though with a steep slope) with the trend at smaller sizes (11 ≤ n ≤ 14).
- 10 February 2026
- Published by American Chemical Society (ACS) in Analytical Chemistry
- Vol. 98 (7) , 5284-5291
Tandem Mobility Measurements of Ionic Liquid Cluster Volatilities
We illustrate the potential of a pair of steady-state ion mobility filters run in series, similar to a triple quadrupole mass spectrometer, not only to operate under atmospheric pressure but also to determine reaction kinetics at controlled pressure and temperature. Singly charged cluster cations of the ionic liquid 1-ethyl-3-methyl-imidazolium tris(pentafluoroethyl)trifluorophosphate (EMI-FAP) produced by a bipolar electrospray source are isolated steadily at atmospheric pressure by a first ion mobility spectrometer (IMS). A second IMS then determines the composition of evaporative decay products: (EMI-FAP)n-1EMI+→(EMI-FAP)n-2EMI++EMI-FAP (2 ≤ n ≤ 30) after passing through a heated parabolic flow reactor tube at controlled temperatures T (23-40 °C). Measured product/parent abundance ratios are converted into reaction constants kn via a previously described theory. At n < 11, evaporation rates kn exhibit idiosyncrasies characteristic of various magic numbers, some of which are also reflected in a cluster compactness parameter inferred from the measured mobility cross section and mass. An approximately continuous variation of volatility with n is found for 11 ≤ n ≤ 14, and for n ≥ 19, with a region of low volatility in between. This especially stable domain of four clusters (15 ≤ n ≤ 18) is reached on the right (n = 18) with a discontinuous (4-fold) volatility decrease, suggesting a transition to a liquid-like structure. On the left it merges continuously (though with a steep slope) with the trend at smaller sizes (11 ≤ n ≤ 14).
- 6 February 2026
- Published by Taylor & Francis in Aerosol Science and Technology
- Vol. 60 (8) , 947-961
A tandem DMA system for detailed balance studies of cluster decomposition kinetics: Experimental setup and quantification of spectra
- 6 February 2026
- Published by Taylor & Francis in Aerosol Science and Technology
- Vol. 60 (8) , 947-961
A tandem DMA system for detailed balance studies of cluster decomposition kinetics: Experimental setup and quantification of spectra
- 4 February 2026
- Published by Elsevier in Journal of Aerosol Science
- Vol. 193
Time of flight studies of cluster reaction-diffusion in parabolic flow reactor tubes
- 4 February 2026
- Published by Elsevier in Journal of Aerosol Science
- Vol. 193
Time of flight studies of cluster reaction-diffusion in parabolic flow reactor tubes
- Open Access
- 14 January 2026
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1027, A11
On the quasi-ionic emission regime of electrified ionic liquids from capillary sources, and its transition into the purely ionic regime
Negatively electrified liquid cone jets supported on capillary tubes with 30–36 $ \,\unicode{x03BC} \text{m}$ tip diameters are investigated in vacuo with four ionic liquids (ILs) selected for their high electrical conductivity and low viscosity. All four use the same cation 1-ethyl-3-methylimidazolium $^+$ ( $ \text{EMI}^+$ ), paired with the four anions $\textrm{SCN}^-$ , $\text{N}(\text{CN})_2^-$ , $\text{C}(\text{CN})_3^-$ and $ \text{BF}_4^-$ . Purely ionic (PI) emissions are not unambiguously achieved with any of the four, but are closely approached by all under a broad range of conditions. In this unusual quasi-ionic (QI) regime, drops contribute minimally to the current ( $\sim$ 0.5 %–3 %) but substantially to the mass flow. A sharp QI $\rightarrow$ PI transition below a critical liquid flow rate has been demonstrated for capillary emitters by Caballero-Perez et al. (2025) J. Propul. Power , for 1-butyl-3-methylimidazolium-C(CN) $_3$ (BMI-C(CN) $_3$ ) by using 15 $\unicode{x03BC}$ m capillary tips able to stabilise unusually small liquid flow rates. None of their other 3 ILs achieves the QI regime, indicating the singularity of BMI-C(CN) $_3$ and our four ILs. We focus on the peculiarities of the QI regime, the likely mechanism for the QI $\rightarrow$ PI transition and argue that ILs reaching the QI regime will probably also attain the PI regime when sprayed from sufficiently small capillary tips. Paradoxically, while high conductivity and low viscosity appear to favour the QI mode, for a liquid operating in this regime, inverting these properties by lowering the emitter temperature appears to better approach the PI regime.- 14 January 2026
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1027, A11
Open AccessOn the quasi-ionic emission regime of electrified ionic liquids from capillary sources, and its transition into the purely ionic regime
Negatively electrified liquid cone jets supported on capillary tubes with 30–36 $ \,\unicode{x03BC} \text{m}$ tip diameters are investigated in vacuo with four ionic liquids (ILs) selected for their high electrical conductivity and low viscosity. All four use the same cation 1-ethyl-3-methylimidazolium $^+$ ( $ \text{EMI}^+$ ), paired with the four anions $\textrm{SCN}^-$ , $\text{N}(\text{CN})_2^-$ , $\text{C}(\text{CN})_3^-$ and $ \text{BF}_4^-$ . Purely ionic (PI) emissions are not unambiguously achieved with any of the four, but are closely approached by all under a broad range of conditions. In this unusual quasi-ionic (QI) regime, drops contribute minimally to the current ( $\sim$ 0.5 %–3 %) but substantially to the mass flow. A sharp QI $\rightarrow$ PI transition below a critical liquid flow rate has been demonstrated for capillary emitters by Caballero-Perez et al. (2025) J. Propul. Power , for 1-butyl-3-methylimidazolium-C(CN) $_3$ (BMI-C(CN) $_3$ ) by using 15 $\unicode{x03BC}$ m capillary tips able to stabilise unusually small liquid flow rates. None of their other 3 ILs achieves the QI regime, indicating the singularity of BMI-C(CN) $_3$ and our four ILs. We focus on the peculiarities of the QI regime, the likely mechanism for the QI $\rightarrow$ PI transition and argue that ILs reaching the QI regime will probably also attain the PI regime when sprayed from sufficiently small capillary tips. Paradoxically, while high conductivity and low viscosity appear to favour the QI mode, for a liquid operating in this regime, inverting these properties by lowering the emitter temperature appears to better approach the PI regime. - Open Access
- 15 December 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1025
Self-similar structure of the entry and exit discontinuities in two-way diffusion equations
Two-way diffusion equations arising in kinetic problems relating to electron scattering and in Brownian particle dynamics present singularities absent from conventional diffusion equations. Although calculations by Stein & Bernstein, and Fisch & Kruskal have revealed the formation of entry and exit slope discontinuities at the critical points where the velocity changes sign, the analytical structure of these discontinuities remains unclear. Here we fill this gap via a local similarity variable analysis, illustrated through the two-way diffusion equation $y \partial n/\partial x=\partial ^2 n/\partial y^2$ in $-1 \leq y \leq 1$ ; $0 \leq x \leq L$ , with $n(x,\pm 1)=0$ with various entry conditions $n(0,y)_{y\gt 0}$ , and the exit condition $n(L,y)_{y\lt 0}=0$ . The similarity variable $\eta =y/x^{1/3}$ permits the analytical characterization of the entry discontinuity, except for constants determined by matching with numerical solutions obtained with two numerical schemes: separation of variables following the construction of Beals, or finite-difference discretization of the transient partial differential equation, which converges in time to a solution almost identical to the separation of variables solution. Although the slope discontinuity depends markedly on the initial condition $n(0,y)_{y\gt 0}$ , a simple general similarity solution structure emerges empirically, always involving a spontaneous singular contribution $C |y|^{1/2}$ at $x=0,y\lt 0$ . Slow convergence of both numerical solutions near $\{x,y\}=\{0,0\}$ is attributed to the poor eigenfunction representation of the ever-present singular solution component $|y|^{1/2}$ . The similarity approach applies equally to other two-way diffusion equations when the coefficient of $\partial n/\partial x$ changes sign linearly with $y$ . It can also be extended to situations where this coefficient is discontinuous at the critical points.- 15 December 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1025
Open AccessSelf-similar structure of the entry and exit discontinuities in two-way diffusion equations
Two-way diffusion equations arising in kinetic problems relating to electron scattering and in Brownian particle dynamics present singularities absent from conventional diffusion equations. Although calculations by Stein & Bernstein, and Fisch & Kruskal have revealed the formation of entry and exit slope discontinuities at the critical points where the velocity changes sign, the analytical structure of these discontinuities remains unclear. Here we fill this gap via a local similarity variable analysis, illustrated through the two-way diffusion equation $y \partial n/\partial x=\partial ^2 n/\partial y^2$ in $-1 \leq y \leq 1$ ; $0 \leq x \leq L$ , with $n(x,\pm 1)=0$ with various entry conditions $n(0,y)_{y\gt 0}$ , and the exit condition $n(L,y)_{y\lt 0}=0$ . The similarity variable $\eta =y/x^{1/3}$ permits the analytical characterization of the entry discontinuity, except for constants determined by matching with numerical solutions obtained with two numerical schemes: separation of variables following the construction of Beals, or finite-difference discretization of the transient partial differential equation, which converges in time to a solution almost identical to the separation of variables solution. Although the slope discontinuity depends markedly on the initial condition $n(0,y)_{y\gt 0}$ , a simple general similarity solution structure emerges empirically, always involving a spontaneous singular contribution $C |y|^{1/2}$ at $x=0,y\lt 0$ . Slow convergence of both numerical solutions near $\{x,y\}=\{0,0\}$ is attributed to the poor eigenfunction representation of the ever-present singular solution component $|y|^{1/2}$ . The similarity approach applies equally to other two-way diffusion equations when the coefficient of $\partial n/\partial x$ changes sign linearly with $y$ . It can also be extended to situations where this coefficient is discontinuous at the critical points. - Open Access
- 28 August 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1018, A5
Determination of the characteristic length of electrosprays operating in the cone-jet mode
Gamero-Castaño and colleagues have reported that a large number of calculated shapes for electrified cone jets collapse into a nearly universal geometry when scaled with a characteristic length $R_G$ previously introduced by Gañán-Calvo et al. (J. Aerosol Sci., vol. 25, 1994, pp. 1121–1142). The theoretical reasons for that unexpected success were, however, unclear. Recently, Pérez-Lorenzo & Fernández de la Mora (J. Fluid Mech., vol. 931, 2022, A4) have noted that a slightly different length scale $L_j$ is suggested by the asymptotic jet structure inferred by Gañán-Calvo (Phys. Rev. Lett., vol. 79, 1997, pp. 217–220) from energy conservation and the hypothesis that the asymptotic electric field is that given by Taylor’s static model. This article aims to identify which of these two scales best collapses calculated cone-jet structures, and whether there is an alternative superior one. The characteristic lengths are tested against a large set of numerical solutions of a cone-jet model. The effectiveness of each scaling is determined through analyses based on the standard deviation of the numerical solutions. Despite the slight difference between $R_G$ and $L_j$ , this analysis clearly identifies $L_j$ as the most accurate scaling for all cone-jet parameters tested. Differentiating between both scales would not have been possible with experimental measurements, but requires the use of high-fidelity numerical solutions. Surprisingly, the success of $L_j$ is not limited to the jet region, but extends to the cone and the neck. These findings provide a slightly superior scaling enjoying a considerably firmer theoretical basis.- 28 August 2025
- Published by Cambridge University Press (CUP) in Journal of Fluid Mechanics
- Vol. 1018, A5
Open AccessDetermination of the characteristic length of electrosprays operating in the cone-jet mode
Gamero-Castaño and colleagues have reported that a large number of calculated shapes for electrified cone jets collapse into a nearly universal geometry when scaled with a characteristic length $R_G$ previously introduced by Gañán-Calvo et al. (J. Aerosol Sci., vol. 25, 1994, pp. 1121–1142). The theoretical reasons for that unexpected success were, however, unclear. Recently, Pérez-Lorenzo & Fernández de la Mora (J. Fluid Mech., vol. 931, 2022, A4) have noted that a slightly different length scale $L_j$ is suggested by the asymptotic jet structure inferred by Gañán-Calvo (Phys. Rev. Lett., vol. 79, 1997, pp. 217–220) from energy conservation and the hypothesis that the asymptotic electric field is that given by Taylor’s static model. This article aims to identify which of these two scales best collapses calculated cone-jet structures, and whether there is an alternative superior one. The characteristic lengths are tested against a large set of numerical solutions of a cone-jet model. The effectiveness of each scaling is determined through analyses based on the standard deviation of the numerical solutions. Despite the slight difference between $R_G$ and $L_j$ , this analysis clearly identifies $L_j$ as the most accurate scaling for all cone-jet parameters tested. Differentiating between both scales would not have been possible with experimental measurements, but requires the use of high-fidelity numerical solutions. Surprisingly, the success of $L_j$ is not limited to the jet region, but extends to the cone and the neck. These findings provide a slightly superior scaling enjoying a considerably firmer theoretical basis. - 25 June 2025
- Published by Elsevier in Journal of Colloid and Interface Science
- Vol. 698, 138236
Corrigendum to “The smallest nanodrop describable via macroscopic interfacial concepts: Testing classical heterogeneous nucleation theory with perfect wetting down to 3 nm” [J. Colloid Interface Sci. 658 (2024) 562–570]
- 25 June 2025
- Published by Elsevier in Journal of Colloid and Interface Science
- Vol. 698, 138236
Corrigendum to “The smallest nanodrop describable via macroscopic interfacial concepts: Testing classical heterogeneous nucleation theory with perfect wetting down to 3 nm” [J. Colloid Interface Sci. 658 (2024) 562–570]