Cost-effective 3D-printed rotatable reflectors for two-dimensional beam steering.

In this paper, we have developed a 2D optical scanning module comprising cascaded 3D-printed one-axis rotating mirrors with large areas (30×30m m 2 for the X-direction scan and 60×25m m 2 for the Y-direction scan). Each mirror device contains a square or rectangular silicon substrate coated with aluminum, serving as the mirror. A 3D-printed structure, including the mirror frame (with four embedded mini permanent magnets on the backside), torsion springs, and base, is combined with the mirror; two electromagnets are situated under the mirror as the actuation mechanism. We apply DC voltage to the electromagnets to create magnetic force. The electromagnets can interact with the permanent magnets to make the mirror rotate. The X scan of the 2D scanning module can achieve a static optical scan angle of ∼11.8deg at the -X corners, and the corresponding Y-scan angle is ∼4.5deg, both with 12 VDC. Moreover, we have observed a fan-shaped distortion, a phenomenon not thoroughly studied previously for combining two single-axis scan mirrors. Therefore, we also perform a simulation to establish and demonstrate a correlation between the simulation prediction and experimental results. The 2D scanning module can be a low-cost alternative to the expensive conventional galvanometer scanners, and it can be used to upgrade a rangefinder to a simplified LiDAR.

High antimicrobial activity of lactoferricin-expressing Bacillus subtilis strains.

The lactoferricin expressed in Bacillus subtilis is relatively low in yield, making it hard to apply in industrial settings. We constructed a six tandem repeat of lactoferricin cDNA driven by promoter PtrnQ. After transformation, two transformants P245 and P263 possessing a stable inheritance of plasmid and high expression of lactoferricin were selected. The bactericidal activities, 1 µl of aliquot of a total 5.5 ml of solution extracted from 5 ml of cultured P245 and P263, were equivalent to the efficacy of 238.25 and 322.7 ng of Ampicillin against Escherichia coli, respectively, and 366.4 and 452.52 ng of Ampicillin against Staphylococcus epidermidis respectively. These extracts were able to kill an Ampicillin-resistant E. coli strain. The bactericidal activities of P245 and P263 equivalent to the efficacy of Tetracycline against Vibrio parahaemolyticus and V. alginolyticus were also determined. Moreover, the bactericidal activities of P245 and P263 were 168.04 and 249.94 ng of Ampicillin against Edwardsiella tarda, respectively, and 219.7 and 252.43 ng of Tetracycline against Streptococcus iniae respectively. Interestingly, the survival rate of E. tarda-infected tilapia fry fed the P263 extract displayed a significantly greater than that of the fry-fed control strain. Collectively, these B. subtilis transgenic strains are highly promising for use in animal husbandry during a disease outbreak.

Using Bacillus subtilis as a Host Cell to Express an Antimicrobial Peptide from the Marine Chordate Ciona intestinalis.

Ciona molecule against microbes-A24 (CiMAM) isolated from the marine chordate Ciona intestinalis is an antimicrobial peptide. To generate CiMAM-expressing transgenic Bacillus subtilis, we constructed a plasmid expressing recombinant CiMAM (rCiMAM) and introduced it into B. subtilis. Transgenic strains C117 and C166 were selected since they were able to highly and stably express rCiMAM. We studied the bactericidal activity of pepsin-digested extracts from rCiMAM-expressing strains against freshwater and euryhaline pathogens that commonly occur in aquaculture ponds and found no difference from that of lactoferricin-expressing strains. The bactericidal activity of 1-µL aliquot from a total 5.5 mL extracted from 5 mL of cultured C117 (1.45 × 108 CFU·mL-1) and C166 (2.17 × 108 CFU·mL-1) against halophilic bacteria was equivalent to the efficacy of 57.06 and 32.35 ng of Tetracycline against Vibrio natriegens, 47.07 and 25.2 ng against V. parahaemolyticus, and 58.17 and 36.55 ng against V. alginolyticus, respectively, indicating higher bactericidal activity of pepsin-extracts from rCiMAM-containing strains against halophilic bacteria compared to that from lactoferricin-containing strains. Since the antibacterial activity of rCiMAM-expressing B. subtilis strains shows higher competence against halophilic pathogens compared to that against freshwater and euryhaline pathogens, these strains are promising candidates to protect marine fish and shellfish from halophilic bacterial infection.

Enzyme-crosslinked gene-activated matrix for the induction of mesenchymal stem cells in osteochondral tissue regeneration.

The development of osteochondral tissue engineering is an important issue for the treatment of traumatic injury or aging associated joint disease. However, the different compositions and mechanical properties of cartilage and subchondral bone show the complexity of this tissue interface, making it challenging for the design and fabrication of osteochondral graft substitute. In this study, a bilayer scaffold is developed to promote the regeneration of osteochondral tissue within a single integrated construct. It has the capacity to serve as a gene delivery platform to promote transfection of human mesenchymal stem cells (hMSCs) and the functional osteochondral tissues formation. For the subchondral bone layer, the bone matrix with organic (type I collagen, Col) and inorganic (hydroxyapatite, Hap) composite scaffold has been developed through mineralization of hydroxyapatite nanocrystals oriented growth on collagen fibrils. We also prepare multi-shell nanoparticles in different layers with a calcium phosphate core and DNA/calcium phosphate shells conjugated with polyethyleneimine to act as non-viral vectors for delivery of plasmid DNA encoding BMP2 and TGF-ß3, respectively. Microbial transglutaminase is used as a cross-linking agent to crosslink the bilayer scaffold. The ability of this scaffold to act as a gene-activated matrix is demonstrated with successful transfection efficiency. The results show that the sustained release of plasmids from gene-activated matrix can promote prolonged transgene expression and stimulate hMSCs differentiation into osteogenic and chondrogenic lineages by spatial and temporal control within the bilayer composite scaffold. This improved delivery method may enhance the functionalized composite graft to accelerate healing process for osteochondral tissue regeneration. STATEMENT OF SIGNIFICANCE: In this study, a gene-activated matrix (GAM) to promote the growth of both cartilage and subchondral bone within a single integrated construct is developed. It has the capacity to promote transfection of human mesenchymal stem cells (hMSCs) and the functional osteochondral tissues formation. The results show that the sustained release of plasmids including TGF-beta and BMP-2 from GAM could promote prolonged transgene expression and stimulate hMSCs differentiation into the osteogenic and chondrogenic lineages by spatial control manner. This improved delivery method should enhance the functionalized composite graft to accelerate healing process in vitro and in vivo for osteochondral tissue regeneration.

Cranioplasty Using a Novel Osteoconductive Scaffold and Platelet Gel.

BACKGROUND: Commonly used materials for cranioplasty include autogenous bone grafts, methyl methacrylate, and titanium mesh. We evaluated a novel osteoconductive scaffold [N-isopropylacrylamide cross-linked with acrylic acid using γ-rays (ANa powder)] mixed with platelet gel for cranioplasty. METHODS: ANa powder mixed with platelet gel was implanted into a 15 × 15-mm, full-thickness calvarial bone defect in 5 New Zealand white rabbits. ANa powder mixed with phosphate-buffered saline was implanted in 5 rabbits. The calvarial bone defect was left unreconstructed in another 5 rabbits. Twelve weeks after surgery, computed tomography examination was used to evaluate the radiographic evidence of bone healing in vivo. Bone specimens were then retrieved for histologic study. RESULTS: The ANa scaffold mixed with platelet gel is biocompatible, biodegradable, and both osteoconductive and osteoinductive, leading to progressive growth of new bone into the calvarial bone defect. CONCLUSION: The use of this novel osteoconductive scaffold combined with osteoinductive platelet gel offers a valuable alternative for the reconstruction of calvarial bone defects.

Electrothermally-Actuated Micromirrors with Bimorph Actuators--Bending-Type and Torsion-Type.

Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA). A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively.

Tailored design of electrospun composite nanofibers with staged release of multiple angiogenic growth factors for chronic wound healing.

The objective of this research study is to develop a collagen (Col) and hyaluronic acid (HA) inter-stacking nanofibrous skin equivalent substitute with the programmable release of multiple angiogenic growth factors (vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), basic fibroblast growth factor (bFGF) and endothelial growth factor (EGF)) either directly embedded in the nanofibers or encapsulated in the gelatin nanoparticles (GNs) by electrospinning technology. The delivery of EGF and bFGF in the early stage is expected to accelerate epithelialization and vasculature sprouting, while the release of PDGF and VEGF in the late stage is with the aim of inducing blood vessels maturation. The physiochemical characterizations indicate that the Col-HA-GN nanofibrous membrane possesses mechanical properties similar to human native skin. The design of a particle-in-fiber structure allows growth factors for slow controlled release up to 1month. Cultured on biodegradable Col-HA membrane with four kinds of growth factors (Col-HA w/4GF), endothelial cells not only increase in growth rate but also form a better network with a thread-like tubular structure. The therapeutic effect of Col-HA w/4GF membrane on streptozotocin (STZ)-induced diabetic rats reveals an accelerated wound closure rate, together with elevated collagen deposition and enhanced maturation of vessels, as revealed by Masson's trichrome stain and immunohistochemical analysis, respectively. From the above, the electrospun Col-HA-GN composite nanofibrous skin substitute with a stage-wise release pattern of multiple angiogenic factors could be a promising bioengineered construct for chronic wound healing in skin tissue regeneration.

Dental optical coherence tomography.

This review paper describes the applications of dental optical coherence tomography (OCT) in oral tissue images, caries, periodontal disease and oral cancer. The background of OCT, including basic theory, system setup, light sources, spatial resolution and system limitations, is provided. The comparisons between OCT and other clinical oral diagnostic methods are also discussed.

Treatment of nonhealing diabetic lower extremity ulcers with skin graft and autologous platelet gel: a case series.

Lower extremity ulcers in diabetic patients are difficult to treat. Recently, the use of human blood platelet-derived components in this indication has been raising interest. In this study, we have evaluated the safety and efficacy of the combination of autologous platelet gel (PG) and skin graft for treating large size recalcitrant ulcers. Eight consecutive diabetic patients aged 25 to 82 with nine nonhealing lower extremity ulcers (median size of 50 cm(2); range 15-150 cm(2)) were treated. Skin ulcer was debrided, and the wound was sprayed after 7 to 10 days with autologous platelet-rich plasma and thrombin. Thin split-thickness skin graft with multiple slits was then applied on the wound bed and fixed with staples or cat-gut sutures. There were no adverse reactions observed during the study. Eight out of 9 skin grafts took well. The interval between skin graft and complete wound healing ranged from 2 to 3 weeks in the 8 successful cases. No ulcer recurrence was noted in those patients during the follow-up period of 2 to 19 months. In this study, the combination of autologous platelet gel and skin grafting has proven beneficial to heal large-size recalcitrant ulcers.

Single-donor allogeneic platelet fibrin glue and osteoconductive scaffold in orbital floor fracture reconstruction.

BACKGROUND: Commonly used materials for orbital floor fracture reconstruction include autologous cranial bone graft and titanium mesh. We have evaluated here a biomaterial combining biphasic calcium phosphate (hydroxyapatite [HA]/ß-tricalcium phosphate [TCP]) osteoconductive scaffold with single-donor allogeneic platelet fibrin glue. METHODS: The study was conducted on 10 consecutive patients with a follow-up of up to 4 years. Platelet fibrin glue was prepared by mixing equal volumes of single-donor platelet-rich plasma and cryoprecipitate with HA/ß-TCP followed by activation with human thrombin prepared by plasma activation. Postoperative evaluations included serial photographs, repeated physical examination, and 3-dimensional computed tomography scan performed 2 years after surgery. RESULTS: The fibrin-rich platelet biomaterial was easy to mold and to apply on the surgical site allowing the surgeon to sculpt accurately the bone defect, providing mechanical stability while avoiding spillage of the scaffold. No infection of the orbit or extrusion of HA/ß-TCP was observed. Ocular motility was normal, and no diplopia or enophthalmos of the injured orbit was noted. Coronal computed tomography scans of the reconstructed orbits revealed good restoration of the orbital floor defect in all 10 patients. CONCLUSIONS: The use of single-donor platelet fibrin glue combined with an osteoconductive scaffold offers a valuable alternative to autologous cranial bone graft or titanium mesh in the reconstruction of orbital floor bone defect.

Modeling of micro cat's eye retroreflectors using a matrix-based three-dimensional ray tracing technique.

In this paper we develop a three-dimensional (3D) ray tracing tool based on the ABCD ray transfer matrices. With symmetric optical components and under paraxial approximation, two sets of 2×2 ABCD matrices, each for a two-dimensional subspace, can be used to describe the 3D ray propagation completely. Compared to commercial ray-tracing software packages, our tool requires no tedious drawing, and the results for various conditions, such as different device dimensions and incident angles, can be easily obtained by simply changing the parameter values used for the calculation. We have employed this matrix-based 3D ray tracing tool to model cat's eye retroreflectors. The cat's eye performance, including the retroreflection efficiency, acceptance angle (i.e., field of view), and beam divergence and deviation, is fully studied. The application of this 3D ray tracing technique can be further extended to other optical components.

Diffuse optical multipatch technique for tissue oxygenation monitoring: clinical study in intensive care unit.

Diffuse optical multipatch technique is used to assess spatial variations in absorption and scattering in biological tissue, by monitoring changes in the concentration of oxyhemoglobin and deoxyhemoglobin. In our preliminary study, the temporal tracings of tissue oxygenation are measured using diffuse optical multipatch measurement and a venous occlusion test, employing normal subjects and ICU patients suffering from sepsis and heart failure. In experiments, obvious differences in tissue oxygenation signals were observed among all three groups. This paper discusses the physiological relevance of tissue oxygenation with respect to disease.

Aorta fluorescence imaging by using confocal microscopy.

The activated leukocyte attacked the vascular endothelium and the associated increase in VEcadherin number was observed in experiments. The confocal microscopic system with a prism-based wavelength filter was used for multiwavelength fluorescence measurement. Multiwavelength fluorescence imaging based on the VEcadherin within the aorta segment of a rat was achieved. The confocal microscopic system capable of fluorescence detection of cardiovascular tissue is a useful tool for measuring the biological properties in clinical applications.

Combination of guided osteogenesis with autologous platelet-rich fibrin glue and mesenchymal stem cell for mandibular reconstruction.

BACKGROUND: This study examined whether a combination of autologous platelet-rich fibrin glue (PRFG) with mesenchymal stem cells (MSCs) and MEDPOR as guided tissue regeneration (GTR) could act as an osteogenic substitute and whether this treatment yields faster new bone formation than MEDPOR alone or PRFG plus MSC. MATERIAL: MSCs were harvested and isolated from the bone marrow of dog ilium. Full-thickness bony defects (1.5×1.5 cm) were created in the bilateral mandible angles of the dog. Treatments for bone defect in each group were as follows: group I (n=4), MEDPOR sheet as GTR and autologous PRFG/MSCs admixtures; group II (n=4), autologous PRFG/MSCs admixtures; group III (n=4), MEDPOR sheet as GTR; and group IV (n=4), control (empty defect). The percentage of new bone regeneration in computerized tomography at 2 months and 4 months was calculated by Analyze version 7.0 software. The mandibles were harvested from all specimens at 4 months, and the grafted sites were evaluated by gross, histologic, and X-ray examination. RESULTS: By radiographic analysis at 16 weeks posttransplantation, it was shown that an average of 72.8%±8.02% new bone formation in group I, 53.34%±6.87% in group II, 26.58%±6.41% in group III, and 15.14%±2.37% in group IV. Histologic examination revealed that the defect was repaired by typical bone tissue in groups I and II, whereas only minimal bone formation with fibrous connection was observed in the groups III and IV group. Besides, muscle incarceration was found in groups II and IV without MEDPOR as GTR. CONCLUSION: Autologous PRFG plus osteoinduced MSCs have good potential for bone regeneration. In combination with MEDPOR as GTR, bone regeneration is enhanced by preventing soft tissue ingrowth hindering bone regeneration.

Solar concentrator constructed with a circular prism array.

We present a novel idea to construct a solar concentrator with a circular prism array. FRED ray tracing software is used to evaluate our proposed structure in which the incident light rays are deflected by total internal reflection and the optical energy is concentrated and collected at the center. The light rays to be collected travel within the disk once they enter the module, saving the space that is reserved for ray propagation in other concentrators. Simulations for both single-wavelength and broadband light are performed. Our device can be used alone or serve as a secondary concentrator when combined with another solar-energy focusing module. For the proposed concentrator, an optical efficiency of 90% (single wavelength, 0.87 microm) is achieved under normal incidence and with antireflection coating, and a high geometric concentration ratio of 93 is reached. When combined with a Fresnel lens, which is used as a primary concentrator, the overall efficiency and concentration ratio can reach 92% (single wavelength, 0.87 microm) and 837, respectively.

A novel technique combining platelet gel, skin graft, and fibrin glue for healing recalcitrant lower extremity ulcers.

BACKGROUND: There is no ideal procedure for the treatment of chronic skin ulcers. The use of platelet gel (PG) in this indication is raising interest. OBJECTIVE: To evaluate the safety and efficacy of a new procedure combining allogeneic single-donor PG and fibrin glue (FG) to enhance skin graft take for treating recalcitrant ulcers. MATERIALS & METHODS: Fifteen patients with 17 ulcers of various etiologies were enrolled. Skin ulcers were débrided, and the wounds covered with moist saline dressing. Three to 14 days later, the wound bed was sprayed with PG, a thin split-thickness skin graft with multiple slits was put on the wound bed, and FG was sprayed on the skin graft. A short leg polypropylene splint was used to immobilize the skin graft. RESULTS: Most skin grafts took well. The interval between skin graft and complete wound healing ranged from 3 weeks to 2 months. No recurrence of ulcers was noted during the 3- to 18-month follow-up period. No adverse reactions were observed. CONCLUSIONS: The procedure provides advantages in skin grafting for recalcitrant ulcers because PG functions as a delivery system of powerful mitogenic and chemostatic factors and FG as a hemostatic tissue sealant that avoids the use of staples or sutures.

Evaluation of bone growth using artificial bone substitute (osteoset) and platelet gel mixtures: a preliminarily study in dogs.

Platelet gels (PG), activated by bovine thrombin (BT), have increasingly been used in orthopedic surgery. However, BT may induce immunological reactions and carry potential viral and prion risks. To avoid these side effects, thrombin derived from human plasma (human thrombin, HT) is becoming the preferred platelet activator to prepare PG. However, limited experience and data on the clinical benefits of HT-generated PG (HTPG) in orthopedic surgery is reported. Consequently, we designed and performed a series of studies in dogs to compare the impacts of promotion of bone growth by an artificial bone substitute (Osteoset) in combination with HTPG or without it in the spinal repair experiments. X-ray observations and histological studies were performed at predetermined periods post-operation. The preliminary results revealed the preparation of HTPG was easy and required less than 30 minutes. HTPG was capable of embedding the artificial bone substitute Osteoset to prepare a sticky and easily manipulated composite for the application into spinal defect. We found HTPG exhibited enhancement of grafting capacity in consolidation of bone mass. After 12 weeks, tissue reconstruction reached approximately 80% of the injury defects when treated by HTPG/Osteoset combination, but only 30 approximately 40% in the absence of HTPG. The physiological activity of artificial bone substitute combined with PG activated by HT may therefore open beneficial prospects for more successful and safer bone formation in spine procedures in the near future.

Cranioplasty using osteoconductive scaffold and platelet glue.

BACKGROUND: An alternative to autogenous bone grafts or to methyl methacrylate in the reconstruction of full-thickness calvarial bone defect is needed. METHODS: The safety and efficacy of biphasic calcium phosphate osteoconductive scaffold (Triosite) combined with platelet glue for the reconstruction of posttraumatic calvarial bone defect was evaluated in six consecutive patients. Follow-up averaged 30 months. Postoperative evaluations included serial photographs, repeated physical examination, and three-dimensional computed tomography scan. RESULTS: High-fibrin concentration of the platelet glue allowed easy molding and sculpting of the scaffold, providing mechanical stability and avoiding spillage of the granules into the operating field. Neither infection of the surgical site nor extrusion of the scaffold was noted. The contour of the reconstructed calvarium was esthetically acceptable, without any secondary depression. Three-dimensional computed tomography scans 2 years after surgery revealed satisfactory reconstruction of the bone defect. Visual inspection of the reconstructed calvarium 2 years after surgery in one patient evidenced conversion of the scaffold into solid new bone. Section of the biopsy demonstrated new bone formation at the expense of the scaffold. CONCLUSION: Combining an osteoconductive scaffold with platelet glue offers an interesting alternative to autogenous bone graft or methyl methacrylate for posttraumatic calvarium bone defect reconstruction.

Analysis of the interchannel response in a MEMS 1 x N(2) wavelength-selective switch.

A theoretical model based on Fourier optics and the power-coupling overlap integral is built to investigate the interchannel response in a micro-electro-mechanical systems 1xN(2) wavelength-selective switch. The simulation results demonstrate that the interchannel response depends significantly on the output port location and the radius of curvature of the micromirrors. For the output originally aligned with the input along the dispersion direction, it is possible to achieve interchannel-response suppression by rotating the two-dimensional (2D) collimator array by a slight angle, e.g., 20 degrees. Experimental results under different conditions are also shown.

Fibrin glue mixed with gelatin/hyaluronic acid/chondroitin-6-sulfate tri-copolymer for articular cartilage tissue engineering: the results of real-time polymerase chain reaction.

Autologous fibrin glue has been demonstrated as a potential scaffold with very good biocompatibility for neocartilage formation. However, fibrin glue has been reported not to provide enough mechanical strength, but with many growth factors to interfere the tissue growth. Gelatin/hyaluronic acid/chondroitin-6-sulfate (GHC6S) tri-copolymer sponge has been prepared as scaffold for cartilage tissue engineering and showed very good results, but problems of cell seeding and cell distribution troubled the researchers. In this study, GHC6S particles would be added into the fibrin glue to provide better mechanical strength, better cell distribution, and easier cell seeding, which would be expected to improve cartilage regeneration in vitro. Porcine cryo-precipitated fibrinogen and thrombin prepared from prothrombin activated by 10% CaCl(2) solution were used in two groups. One is the fibrin glue group in which porcine chondrocytes were mixed with thrombin-fibrinogen solution, which was then converted into fibrin glue. The other is GHC6S-fibrin glue in which GHC6S particles were added into the thrombin-fibrinogen solution with porcine chondrocytes. After culturing for 1-2 weeks, the chondrocytes cultured in GHC6S-fibrin glue showed a round shape with distinct lacuna structure and showed positive in S-100 protein immunohistochemical stain. The related gene expressions of tissue inhibitor of metalloproteinases-1, matrix metalloproteinase-2, MT1-MMP, aggrecan, decorin, type I, II, X collagen, interleukin-1 beta, transforming growth factor-beta 1 (TGF-beta1), and Fas-associating death domain were checked by real-time PCR. The results indicated that the chondrocytes cultured in GHC6S-fibrin glue would effectively promote extracellular matrix (ECM) secretion and inhibit ECM degradation. The evidence could support that GHC6S-fibrin glue would be a promising scaffold for articular cartilage tissue engineering.