Evaluation and Modeling of Polylactide Photodegradation under Ultraviolet Irradiation: Bio-Based Polyester Photolysis Mechanism.

In our study, we investigated the accelerated aging process of PLA under 253.7 nm UV-C irradiation with the use of the GPC, NMR, FTIR, and DSC methods and formal kinetic analysis. The results of GPC and DSC indicated a significant degree of destructive changes in the PLA macromolecules, while spectroscopic methods NMR and FTIR showed maintenance of the PLA main structural elements even after a long time of UV exposure.

Biocomposites Based on Electrospun Fibers of Poly(3-hydroxybutyrate) and Nanoplatelets of Graphene Oxide: Thermal Characteristics and Segmental Dynamics at Hydrothermal and Ozonation Impact.

In order to create new biodegradable nanocomposites for biomedicine, packaging, and environmentally effective adsorbents, ultra-thin composite fibers consisting of poly(3-hydroxybutyrate) (PHB) and graphene oxide (GO) were obtained by electrospinning. Comprehensive studies of ultrathin fibers combining thermal characteristics, dynamic electron paramagnetic resonance (ESR) probe measurements, and scanning electron microscopy (SEM) were carried out. It is shown that at the addition of 0.

Fracture of Epoxy Matrixes Modified with Thermo-Plastic Polymers and Winding Glass Fibers Reinforced Plastics on Their Base under Low-Velocity Impact Condition.

The work is aimed at studying the impact resistance of epoxy oligomer matrices (EO) modified with polysulfone (PSU) or polyethersulfone (PES) and glass fibers reinforced plastics (GFRP) based on them under low-velocity impact conditions. The concentration dependences of strength and fracture energy of modified matrices and GFRP were determined. It has been determined that the type of concentration curves of the fracture energy of GFRP depends on the concentration and type of the modifying polymer.

Hydrolysis, Biodegradation and Ion Sorption in Binary Biocomposites of Chitosan with Polyesters: Polylactide and Poly(3-Hydroxybutyrate).

The film binary composites polylactide (PLA)-chitosan and poly(3-hydroxybutyrate) (PHB)-chitosan have been fabricated and their functional characteristics, such as hydrolysis resistance, biodegradation in soil, and ion sorption behavior have been explored. It was established that hydrolysis temperature and acidity of solutions are differently affected by the weight loss of these two systems. Thus, in the HCl aqueous solutions, the stability of the PHB-chitosan composites is higher than the stability of the PLA-chitosan one, while the opposite situation was observed for biodegradation in soil.

Structure and Properties of Epoxy Polysulfone Systems Modified with an Active Diluent.

An epoxy resin modified with polysulfone (PSU) and active diluent furfuryl glycidyl ether (FGE) was studied. Triethanolaminotitanate (TEAT) and iso-methyltetrahydrophthalic anhydride (iso-MTHPA) were used as curing agents. It is shown that during the curing of initially homogeneous mixtures, heterogeneous structures are formed.

Aggressive Impacts Affecting the Biodegradable Ultrathin Fibers Based on Poly(3-Hydroxybutyrate), Polylactide and Their Blends: Water Sorption, Hydrolysis and Ozonolysis.

Ultrathin electrospun fibers of pristine biopolyesters, poly(3-hydroxybutyrate) (PHB) and polylactic acid (PLA), as well as their blends, have been obtained and then explored after exposure to hydrolytic (phosphate buffer) and oxidative (ozone) media. All the fibers were obtained from a co-solvent, chloroform, by solution-mode electrospinning. The structure, morphology, and segmental dynamic behavior of the fibers have been determined by optical microscopy, SEM, ESR, and others.

Kinetics of photochemical reactions of biphotochromic compounds based on spironaphthopyran and enamine--conjugation effect.

A novel biphotochromic compound (BPC) with two photochromic fragments, namely spironaphthopyran and hydroxyazomethine, was synthesized and studied by nanosecond laser flash photolysis using the excitation wavelengths of 337, 430, 470 and 500 nm in methanol and toluene. The photoexcitation of BPC results in the formation of at least two colored transients. The first one is the merocyanine form B (the maximum in the absorption spectrum is near 600 nm and the lifetime is 0.

Calcium hydroxylapatite filler for facial rejuvenation: a histologic and immunohistochemical analysis.

BACKGROUND Soft-tissue augmentation using calcium hydroxylapatite (CaHA) filler has been shown to be a safe and effective filler agent. A previous study utilizing electron microscopy demonstrated deposition of collagen around filler microspheres with minimal inflammatory response. OBJECTIVE The purpose of this study was to further characterize the expression of collagen in response to injected CaHA filler material using conventional, special, and immunohistochemical (IHC) staining.

Evaluation of clinical, microscopic, and ultrastructural changes after treatment with a novel Q-switched Nd:YAG laser.

Background: The Q-switched Nd:YAG laser was among the first non-ablative lasers to be used. High-fluence photoacoustic Q-switched laser treatments were shown to produce results akin to those seen with some ablative lasers. Previous low-fluence, non-thermal, Q-switched Nd:YAG lasers produced almost no results.

Molecular dynamics simulation of thermomechanical properties of montmorillonite crystal. 3. montmorillonite crystals with PEO oligomer intercalates.

We present the results of molecular dynamics (MD) simulation of the structure and thermomechanical behavior of Wyoming-type Na+-montmorillonite (MMT) with poly(ethylene oxide) (PEO) oligomer intercalates. Periodic boundary conditions in all three directions and simulation cells containing two MMT lamellae [Si248Al8][Al112Mg16]O640[OH]128 oriented parallel to the XY-plane were used. The interlamellar space, or gallery, between neighboring MMT lamellae was populated by 24 Na+ counterions and PEO macromolecules of different lengths, ranging from 2 up to 240 repeat units.

Histologic and ultrastructural analysis of melasma after fractional resurfacing.

Background And Objective: Fractional photothermolysis is a popular treatment option for photodamaged skin and other cutaneous conditions. Recently, successful improvement in melasma has been achieved with this laser system. We undertook this study to evaluate the ultrastructural changes associated with fractional laser treatment of melasma.

Molecular dynamics simulation of thermomechanical properties of montmorillonite crystal. 1. Isolated clay nanoplate.

The structure and mechanical properties of clay nanoparticles is a subject of growing interest because of their numerous applications in engineering. We present the results of molecular dynamics simulation for a single nanoplate of pyrophyllite - a 2:1 clay mineral consisting of two tetrahedral sheets of SiO4 and an intervening octahedral AlO6 sheet. Simulations were performed in the temperature interval from 5 to 750 K using the ionic-type potentials of Cygan et al.

Clinical, laboratory, and MRI analysis of cellulite treatment with a unipolar radiofrequency device.

Background: Cellulite is seen in more than 85% of postpubertal women. Recent studies show that bipolar radiofrequency and low-level laser devices can produce mild skin tightening of cellulite.

Objective: The primary objective was to determine if a novel unipolar, more deeply penetrating, radiofrequency device can promote better skin tightening with fewer treatments than is seen with previously described devices.

Treatment of photoaging with a very superficial Er:YAG laser in combination with a broadband light source.

Background And Objective: Studies documenting improvement following combined laser and light-based devices are needed. The objective of this study was to evaluate clinical, histological, and ultrastructural changes in photodamaged facial skin following sequential treatment with ablative superficial erbium:YAG (Er:YAG) laser peels and nonablative intense pulsed light, or broadband light (BBL), treatments.

Study Design/materials And Methods: Fifteen subjects with photodamaged facial skin and Fitzpatrick skin types I to III underwent 3 monthly treatments with the Profile system (Sciton, Inc, Palo Alto, CA) utilizing very superficial MicroLaserPeel settings of 2.

Cutaneous photoaging treated with a combined 595/1064 nm laser.

Background And Objectives: The pulsed dye laser (PDL) has been used for a variety of vascular changes associated with photoaging. The Nd:YAG laser has been shown to be effective in the treatment of deeper facial vessels, as well as to stimulate new dermal collagen deposition. This study was undertaken to evaluate the safety and efficacy of sequential dual-wavelength PDL and Nd:YAG laser treatment of photoaged facial skin.

Treatment of skin laxity of the lower face and neck in older individuals with a broad-spectrum infrared light device.

Background: Non-ablative approaches with infrared and radiofrequency energy sources have been shown to reduce skin laxity, but studies have focused on individuals with early-stage, mild-to-moderate degenerative dermal changes.

Objective: The purpose of this prospective study was to evaluate the safety and efficacy of an infrared light device for the treatment of skin laxity in patients with soft tissue ptosis of the lower face and neck characteristic of the sixth decade of life and beyond.

Materials And Methods: Thirteen females, aged 58-83 years old (average: 64 years), were treated with a filtered 1100-1800 nm infrared light-based device.

Calcium hydroxylapatite for facial rejuvenation.

Porous calcium hydroxylapatite has been used in otolaryngology, dentistry and radiology for many years. Currently, calcium hydroxylapatite is gaining popularity for facial esthetics in the form of the product Radiesse (San Mateo, CA). Although Radiesse is not yet approved in the United States for cosmetic use, it is being used off-label by an increasing number of dermatologists and plastic surgeons for facial soft-tissue augmentation.

Coexistence of erythromelalgia and Raynaud's phenomenon.

Erythromelalgia is characterized by spontaneous recurrent episodes of redness, heat, and pain of the extremities that can be triggered or worsened by heat. Raynaud's phenomenon occurs in response to cold exposure and presents as pallor of the fingers or toes, often followed by cyanosis and rubor. Although the 2 conditions may appear to be opposites in symptomatology and clinical presentation, there are very rare reports of their coexistence.

Hiccups, eructation, and other uncommon prodromal manifestations of herpes zoster.

Although the most frequent presentation of herpes zoster involves sensory neurons, motor and autonomic symptomatology is also known to occur in this disease. An unusual symptom of hiccups is described here. Other infrequent manifestations of this common illness, including the Ramsay Hunt syndrome, herpes zoster ophthalmicus, urinary and fecal retention, sexual dysfunction, and zoster sine herpete, are reviewed.

Incontinentia pigmenti: a review and update on the molecular basis of pathophysiology.

Unlabelled: Incontinentia pigmenti is an uncommon X-linked dominant disorder, lethal in the majority of affected males in utero and variably expressed in females. Cutaneous manifestations are classically subdivided into 4 stages: vesicular, verrucous, hyperpigmented, and atrophic. Various hair and nail abnormalities, dental anomalies, and ophthalmologic and neurologic deficits are associated with the disorder.

Use of CO2 laser in the treatment of periungual fibromas associated with tuberous sclerosis.

Background: Tuberous sclerosis complex is an autosomal dominant disorder with variable clinical expression. In severe forms it may involve almost any organ system. Periungual fibromas are a common cutaneous manifestation and a frequent source of cosmetic and functional concern.