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Cold EI uses helium as the column carrier and cooling make-up gases at ~50 mL/min. In the rare case that helium supply could be temporarily interrupted, nitrogen or hydrogen can be used, but hydrogen leads to decomposition at the GC injector, and thus, nitrogen is preferred. However, nitrogen leads to longer analysis time and/or reduced separation. We describe the use of helium as the column carrier gas and nitrogen as the cooling make-up gas. In this "Helium Saver" mode, the helium consumption is as in standard EI and nitrogen can be used alone in stand-by mode for further helium saving.

Helium plasma radiofrequency (RF) technology (Renuvion, Apyx Medical, Clearwater, FL) has emerged as a minimally invasive option for treating skin laxity, either as a standalone procedure or as an adjunct to liposuction. While clinical adoption has expanded rapidly, the literature remains heterogeneous, with variable study designs and outcomes. To comprehensively evaluate the safety and performance of helium plasma RF for aesthetic subdermal applications through systematic review and meta-analysis. A systematic search was performed from initial device clearance through May 2025, following PRISMA guidelines. Eligible studies included randomized controlled trials, prospective cohorts, retrospective reviews, and case series with ≥10 patients undergoing aesthetic subdermal treatment with helium plasma RF. Safety outcomes were tabulated and weighted incidence rates calculated. Random-effects meta-analyses were performed to generate pooled estimates for performance endpoints, including patient satisfaction, investigator global aesthetic improvement scale (GAIS), patient GAIS, and independent photographic review scores. Thirty-four studies across 33 publications encompassing 3508 patients were included. Pooled complication rates were 5% for helium plasma RF-only, 8% for helium plasma RF + liposuction, and 15% for combination procedures involving multimodal excisional surgery; differences between groups were not statistically significant (P = .14). The pooled patient satisfaction rate was 92%. Meta-regression demonstrated higher satisfaction with longer follow-up durations (P = .003). This systematic review and meta-analysis suggest that helium plasma RF is associated with a favorable safety profile and high rates of patient satisfaction and aesthetic improvement in subdermal applications. Level of Evidence: 4 (Therapeutic) For image description, please refer to the figure legend and surrounding text.

Objective.To determine beam quality correction factors,, in single-layer scanned carbon and helium ion beams using water calorimetry, thereby reducing uncertainties in dosimetry for light ion therapy.Approach.Water calorimetry measurements were performed under harmonized conditions at two synchrotron-based ion beam therapy centers (MedAustron, Austria and HIT, Germany). Measurements were conducted in the plateau region of single-layer scanned beams. Carbon ion beams covered nominal energies from 213.4-402.8 MeV/u, while helium ion beams were measured at 196.3 and 198.8 MeV/u. Multiple cylindrical (IBA FC65-G, PTW 30013) and plane-parallel (IBA PPC05, PPC40; PTW 34001, 34045) ionization chamber types were investigated.Results.-factors were determined with standard uncertainties of approximately 1%, depending on chamber type and measurement condition. For all investigated chambers, inter-center agreement was observed within the combined standard uncertainties. Chamber-to-chamber variability was below 0.5% for chamber types for which two samples were available, except for the IBA PPC05, for which differences up to 1.3% were observed. For carbon ion beams, the measured-factors are consistent with previously published water calorimetry-based results. However, systematic deviations up to 3% persist between experimentally determined and Monte Carlo-derivedvalues. The measured-factors for helium ions show trends that are broadly similar to those observed in carbon ion beams across all chamber types.Significance.This work expands the experimental-database for light ions by providing new carbon ion data and the first experimental-factors for helium ion beams. These results provide essential experimental data for future refinement of dosimetry recommendations, and highlight persistent discrepancies between the experimental and Monte Carlo-based-factors that require further investigation.

Radiotherapy is a key in cancer treatment, with particle therapy providing better tumor targeting and sparing healthy tissues. Particle Minibeam Radiotherapy (PMBT) integrates the advantages of spatial fractionation into particle radiotherapy by employing submillimeter-sized beams, thus improving the therapeutic ratio by reducing side effects. Former simulation studies have shown that interlaced proton minibeams from opposing directions in Single Energy Distal-Edge (1E) mode better protect normal tissue compared to the conventional spread-out Bragg peak (SOBP) mode. Helium and carbon ion minibeams may be an alternative to enhance the protection of healthy tissue, especially in deeper regions, due to less angular spread. This in silico study evaluates the potential for normal tissue sparing while preserving the same cell survival in the tumor in case of proton, helium and carbon minibeams in 1E mode. Simulations were performed using TOPAS (Tool for Particle Simulation) by applying single-energy interlaced minibeams (beam size σ = 0.2 mm) from two opposing directions in a 250 mm-thick water phantom, assuming a 50 mm-thick tumor at the center. For the comparative analysis, cell survival rates were calculated across the whole phantom using the saturation-corrected Microdosimetric Kinetic Model (MKM-z*) implemented through MONAS (Microdosimetry-based modeling for RBE assessment). As a dose constraint, the minimum dose in the tumor was selected to ensure a maximum of 10% cell survival within the tumor. The sparing of healthy tissues was estimated using the Linear Quadratic (LQ) model, considering variable Relative Biological Effectiveness (RBE) via MONAS. The findings show that helium and carbon minibeams offer enhanced protection of the normal tissues only ∼ 1-2 mm close to the tumor borders, while protons achieve an overall better sparing in the rest of the phantom for the 1E mode, when looking purely at the cell survival. Although protons achieved the highest mean cell survival in normal tissue, the actual sparing effect is strongly influenced by beam size and valley dose, with helium and carbon ions showing enhanced confinement of damage near the tumor edge. These findings highlight the need for the implementation of more anatomically accurate phantoms with more concise biological data as a basis.

In the present paper we study two challenging problems for helium-type systems: the existence of eigenvalues at thresholds and the asymptotic behavior of the corresponding eigenfunctions. Since the usual methods for addressing these problems need a safety distance to the essential spectrum, they cannot be applied in critical cases, when an eigenvalue enters the continuum. We develop a method to address both problems and derive sharp upper and lower bounds for the asymptotic behavior of the ground state of critical helium-type systems at the threshold of the essential spectrum. This is the first proof of the precise asymptotic behavior of the ground state for this benchmark problem in quantum chemistry. Moreover, our bounds describe precisely how the asymptotic decay of the ground state changes, when the system becomes critical.

Objective.Secondary neutrons are an unavoidable by-product of ion beam therapy and contribute to out-of-field doses. Quantifying these doses is crucial for ensuring the safety of the patients, particularly for paediatric patients.Approach.Out-of-field neutron measurements were performed for protons, helium ions and carbon ions, treating a 10-year-old paediatric phantom with a virtual brain tumour. Neutron spectrometry was performed using a Bonner sphere spectrometer, and ambient dose equivalents,H∗(10), were additionally measured with an extended-range rem counter (WENDI II). Both measurements were carried out at two locations in the treatment room, positioned upstream and downstream of the primary beam. Monte Carlo (MC) simulations were used to obtaina priorispectra for the unfolding and to complement the measurements.Main results.The measured neutron energy spectra showed the characteristic features of secondary neutrons in ion beam therapy, consistent with the MC simulations. For all three ions, both the fast neutron and high-energy neutron peaks were observed at the downstream position, along with thermal and epithermal neutron contributions, while no high-energy neutron peak was observed upstream. The highest ambient dose equivalentH∗(10)measured with WENDI II was 11.8μSv per 4 Gy relative biological effectiveness (RBE) for helium ions at the downstream position, and the lowest value of 1.1μSv per 4 Gy(RBE) was obtained by the MC simulations for carbon ions upstream.Significance.The energy distribution of the secondary neutrons during ion beam treatment of a paediatric phantom was successfully measured and used to estimate the ambient dose equivalent.

Combining helium, carbon or oxygen beams with minibeam radiation therapy (MBRT) may benefit the treatment of radioresistant tumours while better protecting healthy tissues from radiation toxicities. In this study, the biomolecular response of glioma cell lines to HeMBRT, CMBRT and OMBRT was evaluated using synchrotron-based Fourier transform infrared microspectroscopy (SR-FTIRM). F98 (rat glioma) and U-87 MG (human glioma) cell lines were subjected to conventional broad beam RT (BB) or MBRT at the Heidelberg Ion-Beam Therapy Centre (Germany). Biomolecular effects were assessed with SR-FTIRM at the MIRAS beamline of the ALBA Synchrotron (Spain). Principal component analysis (PCA) uncovered the spectral alterations due to the different irradiation modalities. In F98 cells, IR signatures in the 1254-1225 cm-1 spectral region, mainly related to DNA and RNA geometries, were altered by both BB and MBRT modalities and the two ion species. Alterations of IR signatures in the 1097-1074 cm-1 spectral region, associated with the phosphodiester backbone of nucleic acids, and IR signatures associated with C-O vibrational modes in the 1110-1097 cm-1 (mainly due to nucleic acids), 1182-1163 cm-1 (mainly due to phospholipids), 1135-1110 cm-1 and 1071-1040 cm-1 (mainly due to carbohydrates) spectral regions, were generally enhanced by CMBRT; OBB and OMBRT also resulted in dose-dependent modifications of these spectral bands, suggesting nucleic acid modifications or oxidative damage. CMBRT, OBB and OMBRT also induced changes in IR signatures of the Amide I band associated with α-helical and β-sheet protein secondary structures, which might result from protein oxidation or cell death mechanisms. In U-87 MG cells, specific IR signatures in the Phosphate II band (i.e. 1173 cm-1, 1150 cm-1, 1080 cm-1, 1065 cm-1 and 1025 cm-1), primarily associated with C-O signals present in phospholipids, carbohydrates and the phosphodiester backbone of nucleic acids, were greatly affected by helium-, carbon- and oxygen-ion RT, in both conventional and spatially fractionated modes. Biomolecular changes in the C-H vibrational modes of lipids for both cell lines were consistent with free radical attacks. Cell viability results revealed cell line-dependent sensitivities to treatment, with findings consistent with the modifications observed in the SR-FTIRM analysis.

Plasma-based devices are increasingly used for skin rejuvenation and epidermal peeling; however, standardized parameters for different plasma gases remain insufficient. Argon (Ar) and helium (He) plasma exhibit distinct physical and biological characteristics, necessitating systematic evaluation to define safe and reproducible treatment conditions. An ex vivo human skin explant model was used to evaluate Ar and He plasma generated by the Plasma Magic device under standardized pulse conditions (1 Hz, 500 ms, 2 pulses). Multiple output levels were assessed to identify parameters achieving complete epidermal peeling without dermal injury. Histological analyses and quantitative RT-PCR of extracellular matrix (ECM)-related genes were performed up to 14 days post-treatment. The effects of adjunctive Lactovesicle application were also evaluated. Ar plasma at level 6 and He plasma at level 8 consistently induced uniform epidermal detachment while preserving dermal architecture and maintaining stable inflammatory cell counts. Collagen and elastin synthesis significantly increased between days 7 and 14, accompanied by marked upregulation of ECM-related genes. He plasma showed stronger long-term elastin synthesis and gene induction, whereas Ar plasma promoted faster initial peeling and early collagen remodeling. Lactovesicle application further enhanced ECM regeneration. Optimized Ar and He plasma parameters enable controlled epidermal peeling and sustained dermal remodeling without tissue damage. Plasma-assisted treatment, particularly when combined with topical Lactovesicle, represents a promising strategy for skin rejuvenation and transdermal therapy. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

This paper reports an atmospheric pressure non-thermal plasma jet device (mini plasma jet) for antibacterial application. The device includes a glass tube, two copper ring electrodes, a custom-made power supply, a helium supply source, and flow control system. The power supply in our device is smaller and lighter compared to other commercially available power supplies. The plasma jet tube is made using a standard glass tube with a narrow outlet. We also simulated the electric field distribution inside and outside the glass tube using COMSOL Multiphysics and optimized the ring electrode distance based on the simulation results. The final system including the power supply and glass tube costs less than U.S. $45. Additionally, our mini plasma jet demonstrates excellent antibacterial performance and outperforms two commercial portable plasma jet devices (kINPen® MED Plasma Jet and J-Plasma®) and a lab-based plasma jet system with respect to in vitro antimicrobial efficacy. Our mini plasma jet eradicated five different strains of bacteria in planktonic culture (Staphylococcus aureus ATCC 25923, ATCC 33592, ATCC BAA-1717, and EMRSA-16, as well as Pseudomonas aeruginosa PAO1) within 40 s, which is significantly shorter than the eradication times required by commercial and the lab-based plasma jets under the same conditions. In contrast, two commercial plasma jets could not disinfect effectively within 300 s and the lab-based system within 180 s. The test results show that our mini plasma jet can generate more reactive oxygen species (ROS, specifically H2O2) and reactive nitrogen species (RNS, specifically NO3 -) than the other three systems.

This study investigated the long-term neurobehavioral and physiological impacts of low-dose helium (4He) ion exposure-a key component of galactic cosmic radiation-on male Long Evans rats. After training on the rodent psychomotor vigilance test (rPVT), the rats were irradiated and monitored for up to 180 days to assess sustained attention and social recognition memory, alongside blood and bone analyses. Results showed that acute exposure to 25 cGy 4He ions significantly impaired sustained attention, increasing attention lapses and reaction times, and decreasing task accuracy. Exposure to 5 cGy only affected specific reaction time measures. However, both doses caused persistent social recognition memory impairments for 180 days. While overall bone mechanics remained largely unchanged, specific skeletal strength parameters were affected. Importantly, significant correlations emerged between behavioral performance and circulating cytokines (IL-1beta), undercarboxylated osteocalcin (ucOC), and bone biomechanics. This suggests these blood and bone targets could serve as diagnostic biomarkers for radiation-induced neurobehavioral deficits. The sustained and progressive nature of the neurobehavioral deficits observed underscores the critical need for effective countermeasures to protect astronaut health and performance during exploration-class missions.

Understanding vibrational lifetimes at surfaces is central to advancing our knowledge of thermal transport, energy dissipation, and nanoscale friction. While phonon lifetimes in the bulk are routinely accessed via inelastic neutron scattering or optical phonon modes via high-resolution Raman spectroscopy, the direct measurement of lifetimes for low-energy surface acoustic phonons, particularly at finite wavevector, remains a major experimental challenge. This is due to the extremely narrow linewidths involved, corresponding to picosecond lifetimes and requiring µeV energy resolution. Here, we demonstrate how helium spin-echo (HeSE) spectroscopy overcomes this limitation, enabling direct access to the intrinsic linewidths and lifetimes of surface vibrational modes. For Ag(001), we map the full dispersion of the Rayleigh wave. Temperature-dependent measurements at finite wavevector reveal its weak anharmonicity and allow extraction of its intrinsic linewidth from the associated broadening. This corresponds to a phonon lifetime of ≈29 ps at 0 K and a propagation length of ≈44 nm, indicating coherence over tens of nanometres despite electron-phonon and defect-induced scattering. In a complementary application, we explore the vibrational dynamics of organic adsorbates, using cobalt phthalocyanine (CoPc) on Ag(001) as a model system. Low-frequency frustrated translational modes of the adsorbed molecules illustrate HeSE's capability to probe vibrational damping in complex adsorbate-surface systems. The observed linewidths reflect enhanced dissipation arising from intermolecular interactions and coupling to the substrate. These findings establish HeSE as a sensitive probe of vibrational energy dissipation at hybrid organic-metal interfaces. Taken together, these capabilities open new avenues for the quantitative study of phonon lifetimes and linewidths in complex and emergent material systems, including 2D heterostructures and unconventional superconductors, where vibrational dynamics and their coupling to other degrees of freedom play a decisive role.

Garlic (Allium sativum L.) exhibits limited agronomic traits and nutrient use efficiency under conventional cultivation, necessitating innovative non-chemical approaches to enhance productivity. This study evaluated helium-neon (He-Ne) laser and ultraviolet (UVA+B) radiation as sustainable pre-treatment strategies to optimize garlic growth, yield, and nutrient utilization. Garlic cloves were pre-treated with control (no irradiation), He-Ne laser (1, 5, 30, or 60 minutes), or UVA+B ra6diation (1, 5, 30, or 60 minutes). Results demonstrated that He-Ne laser produced dose-dependent improvements, with 60-minute exposure maximizing plant height (20.5%), shoot fresh weight (48.1%), bulb fresh weight (29.1%), bulb yield (29.0%), and nutrient use efficiency (nitrogen: 146.6%, phosphorus: 85.1%, potassium: 78.4%). In contrast, UVA+B radiation exhibited a biphasic response, with moderate benefits at low doses (1-5 minutes) but progressive decline at extended exposure (30-60 minutes), reducing yield by 10.7% and nutrient use efficiency by 14.9-29.9%. Response Surface Methodology confirmed 60-minute He-Ne laser pre-treatment as the optimal dose, representing a sustainable strategy for enhancing garlic productivity. These findings demonstrate the potential of laser-based technologies for sustainable vegetable production and warrant further investigation into cultivar-specific optimization and field-scale applications for global food security.

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