Dimensional Issues in Stereolithography

New stereolithography photopolymers have recently been introduced that provide a wider range of functional properties similar to those of high-density polyethylene. One of the important criteria for these materials is the dimensional accuracy and stability in end-use applications as mold masters or the actual functional parts. This work investigates the dimensional stability of one of these new materials with varying amounts of exposure during build. The effect of aging on the part dimensions is reported. The result of environmental humidity extremes at ambient temperature on part dimensions is investigated and compared for parts made from two different families of stereolithography resins, namely DuPont Somos® 7100 and Somos® 8100.Mechanical Engineerin

Influence of Post Curing Conditions on the Mechanical Properties of Stereolithographic Photopolymers

Post cure methods have always been a critical issue for most of the currently used stereolithography photopolymers. Different post cure conditions can be used to enhance the mechanical and physical properties of the stereolithography models. To better understand the influence of post cure conditions on these material properties, an experimental study evaluating various post cure conditions has been conducted. Ultra-violet, thermal and ultra-sound post curing techniques are investigated and a comparative study is made for one epoxy based photopolymer - Somos™ 6100. Similar results should be attainable for other epoxy based photopolymers.Mechanical Engineerin

Investigation of efficient multilevel inverter for photovoltaic energy system and electric vehicle applications

Introduction. This research presents a simple single-phase pulse-width modulated 7-level inverter topology for renewable system which allows home-grid applications with electric vehicle charging. Although multilevel inverters have appealing qualities, their vast range of application is limited by the use of more switches in the traditional arrangement. As a result, a novel symmetrical 7-level inverter is proposed, which has the fewest number of unidirectional switches with gate circuits, providing the lowest switching losses, conduction losses, total harmonic distortion and higher efficiency than conventional topology. The novelty of the proposed work consists of a novel modular inverter structure for photovoltaic energy system and electric vehicle applications with fewer numbers of switches and compact in size. Purpose. The proposed system aims to reduce switch count, overall harmonic distortions, and power loss. There are no passive filters required, and the constituted optimizes power quality by producing distortion-free sinusoidal output voltage as the level count increases while reducing power losses. Methods. The proposed topology is implemented with MATLAB/Simulink, using gating pulses and various pulse-width modulation methodologies. Moreover, the proposed model also has been validated and compared to the hardware system. Results. Total harmonic distortion, number of power switches, output voltage, current, power losses and number of DC sources are investigated with conventional topology. Practical value. The proposed topology has proven to be extremely beneficial for implementing photovoltaic-based stand-alone multilevel inverter and electric vehicle charging applications.Вступ. У цьому дослідженні представлена топологія простого семирівневого однофазного інвертора з широтно-імпульсною модуляцією для системи з відновлюваними джерелами енергії, яка дозволяє використовувати домашню мережу з зарядкою електромобілів. Хоча багаторівневі інвертори мають привабливі характеристики, широкий спектр їх застосування обмежений використанням більшої кількості перемикачів у традиційній схемі. В результаті запропонований новий симетричний 7-рівневий інвертор, який має найменшу кількість односпрямованих ключів із затворними ланцюгами, забезпечує найменші комутаційні втрати, втрати на провідність, сумарні гармонічні спотворення та вищий ККД, ніж традиційна топологія. Новизна запропонованої роботи полягає у новій модульній структурі інвертора для фотоелектричних енергетичних систем та використання для електромобілів з меншою кількістю перемикачів та компактними розмірами. Мета. Пропонована система спрямована на зменшення кількості перемикань, загальних гармонічних спотворень та втрат потужності. Пасивні фільтри не потрібні, а складова частина оптимізує якість електроенергії, створюючи синусоїдальну вихідну напругу без спотворень зі збільшенням кількості рівнів при одночасному зниженні втрат потужності. Методи. Запропонована топологія реалізована за допомогою MATLAB/Simulink з використанням стробуючих імпульсів та різних методологій широтно-імпульсної модуляції. Крім того, запропонована модель також була перевірена та порівняна з апаратною системою. Результати. Загальні гармонічні спотворення, кількість силових ключів, вихідна напруга, струм, втрати потужності та кількість джерел постійного струму досліджуються за допомогою традиційної топології. Практична цінність. Запропонована топологія виявилася надзвичайно корисною для реалізації автономних багаторівневих інверторів на основі фотоелектричних систем та застосування для заряджання електромобілів

Heparin affinity tag and application thereof

In one aspect, affinity tags for recombinant protein purification are described herein which, in some embodiments, can mitigate or overcome disadvantages of prior affinity tag systems. In some embodiments, for example, affinity tags described herein permit efficient elution of desired recombinant proteins with simplified solution systems, such as alkali metal salt solutions. An affinity tag described herein comprises an amino acid sequence including a repeating amino acid unit of BXXXBXX, wherein B is an amino acid selected from the group consisting of histidine, lysine and arginine and X is an amino acid selected from the group consisting of amino acids other than histidine, lysine and arginine

Heparin affinity tag and applications thereof

In one aspect, affinity tags for recombinant protein purification are described herein which, in some embodiments, can mitigate or overcome disadvantages of prior affinity tag systems. In some embodiments, for example, affinity tags described herein permit efficient elution of desired recombinant proteins with simplified solution systems, such as alkali metal salt solutions. An affinity tag described herein comprises an amino acid sequence including a repeating amino acid unit of BXXXBXX, wherein B is an amino acid selected from the group consisting of histidine, lysine and arginine and X is an amino acid selected from the group consisting of amino acids other than histidine, lysine and arginin

Engineered FGF compositions and methods of use thereof

The present invention relates to the development of stable mutants of FGF-1 and FGF-2. In particular, it relates to novel engineered FGF-1 and FGF-2 polypeptides as well as polynucleotides, DNA constructs, and vectors encoding such polypeptides. In another aspect, pharmaceutical compositions and hydrogels including the disclosed polypeptides, polynucleotides, DNA constructs, and vectors are provided. In a still further aspect, methods of treating conditions using the compositions disclosed herein are provided

Bioremediation of Hydrocarbon-Contaminated Environments: Harnessing the Potential of Biosurfactants – A review

Hydrocarbon contamination from industries like petrochemicals threatens the environment and public health. Benzene, toluene, xylene, and polycyclic aromatic hydrocarbons in petroleum products are highly toxic. Conventional cleanup methods are costly and risk secondary pollution. This review highlights biosurfactants, microbially produced compounds that enhance hydrocarbon degradation by lowering surface tension and increasing bioavailability. Biosurfactants are biodegradable and eco-friendly, making them a sustainable alternative to synthetic surfactants. The review intends to cover the biosurfactant sources, types, mechanisms, and their applications in hydrocarbon-contaminated environments. Recent bioremediation advancements, including microbial-enhanced oil recovery, soil and water cleanup, and heavy metal removal, are discussed. Optimizing biosurfactant production is also explored, offering a green and effective solution to combat hydrocarbon contamination and promote environmental restoration

Modulation of Interleukin-12 activity in the presence of heparin

Glycosaminoglycans (GAGs), especially heparin and heparan sulfate (HS), modulate the functions of numerous cytokines. The aims of this multidisciplinary research were to characterize heparin binding to interleukin-12 (IL-12) and determine the mechanism(s) by which heparin influences IL-12 bioactivity. Heparin and HS were found to bind human IL-12 (hIL-12) with low micromolar affinity and increase hIL-12 bioactivity by more than 6-fold. Conversely, other GAGs did not demonstrate significant binding, nor did their addition affect hIL-12 bioactivity. Biophysical studies demonstrated that heparin induced only minor conformational changes while size-exclusion chromatography and small angle X-ray scattering studies indicated that heparin induced dimerization of hIL-12. Heparin modestly protected hIL-12 from proteolytic degradation, however, this was not a likely mechanism for increased cytokine activity in vitro. Flow cytometry studies revealed that heparin increased the amount of hIL-12 bound to cell surfaces. Heparin also facilitated hIL-12 binding and signaling in cells in which both hIL-12 receptor subunits were functionally deleted. Results of this study demonstrate a new role for heparin in modulating the biological activity of IL-12

Engineered FGF1 and FGF2 compositions and methods of use thereof

Engineered FGF1 and FGF2 polypeptides, polynucleotides encoding these polypeptides and DNA constructs, vectors and compositions including these engineered polypeptides are provided herein. The engineered FGF1 and FGF2 polypeptides are more stable than their wild-type counterparts and may be more effective at treating a variety of conditions that FGF1 and FGF2 are useful for treating such as wound healing