Skin Barrier Function

The goal of this clinical trial is to evaluate whether a topical face cream containing the peptide Acetyl Hexapeptide-37 improves skin hydration and strengthens the skin barrier compared to a placebo cream in healthy adult participants. The study uses a split-face design, in which one side of the face is treated with the peptide cream and the other side with a placebo (a cream without the active ingredient). The main questions it aims to answer are: * Does the peptide cream improve skin hydration and reduce transepidermal water loss compared to placebo? * Does the peptide cream affect skin erythema or cause irritation? * How do participants rate the comfort and tolerability of the peptide cream? Researchers will compare the treated and placebo sides of the face to assess differences in skin barrier function and tolerability. Participants will: * Attend a baseline visit for assessment of facial skin parameters, including hydration, transepidermal water loss, and erythema * Apply the peptide cream to one side of the face and the placebo cream to the other side once daily for 4 weeks * Attend weekly follow-up visits for non-invasive skin measurements * Record any skin sensations (e.g., stinging, tightness) or adverse effects throughout the study

This clinical observational study investigates the dose-response relationship between laser energy intensity and skin damage/repair by applying different parameter sets of fractional ablative (CO2) and non-ablative (M22) lasers to the inner forearms of approximately 20 healthy Chinese female volunteers (aged 18-60, Fitzpatrick skin types III-V) in a single-center, self-controlled design. Each participant receives both laser types on contralateral arms, with four distinct energy/density combinations per laser applied to separate test areas, and the dynamic skin responses are evaluated at baseline, immediately post-treatment, and at 30 minutes, 1, 2, 3, 4 hours, 7 days, and 10 days thereafter through clinical assessments (edema, erythema, etc.), standardized photography, high-frequency ultrasound (Dermascan), and objective instrumental measurements of skin color (Chromameter CM26dG), melanin/hemoglobin (Mexameter MX18), and barrier function (TEWL via Vapometer). The collected data will be analyzed using descriptive and comparative statistical methods to characterize the acute injury and recovery profiles, aiming to establish a foundational model for future post-procedure cosmetic intervention research.