Shielding Properties of Lead Zinc Borate Glasses

In the present work, ZnO·PbO·B2O3 glasses are prepared to be used as g-ray shielding materials. The attenuation properties of these glasses with different concentrations of PbO (20% - 70%) have been investigated at photon energies 662, 1173, 1332 and 2614 keV. The optical absorption spectra of some glass samples have been measured from 200 to 1100 nm before and after g-ray irradiation. The analyses of these spectra have been interpreted and discussed.

Preparation and characterization of new sealing glasses based on Li_(2)O-NiO-P_(2)O_(5) system

A series of glass are synthesized via a melt quenching technique based on the Li_(2)O-Ni O-P_(2)O_(5) system.The concentration of nickel oxide varies from 5%to 15%in molar fraction.XRD pattern verifies the amorphous nature of prepared glass samples with 5%,and 10%nickel oxide in molar fraction.While Li_(3)P and Ni_(2)P_(4)O_(12)phases are precipitated with a high nickel content up to 15%in molar fraction.As nickel is substituted for lithium,a systematic increase in glass transition temperature(T_(g))and glass softening temperatures(T_(s))is observed.This is greatly related to the increased structure,coherence in the glass network.Structural investigation showed that Ni_(2+) spectra are present in both octahedral and tetrahedral sites.Physical properties such as glass density((2.38±0.1)-(2.46±0.1)g/cm^(3)),and molar volume((42.28±0.1)-(39.15±0.1)cm^(3)/mol)are examined.The NiO/Li_(2)O replacements led to a decrease in the dissolution rate of the resultant amorphous materials from 1.53×10^(-5)to 3.20×10^(-6)g/(cm^(2)·min).Thermal expansion coefficients CTE of the glasses are diverse from 157×10^(-7) to 96×10^(-7)℃^(-1) over the temperature range of 25-250℃.The prepared glasses are expected to be useful as a low-temperature sealing material.

Double hits with bioactive nanozyme based on cobalt-doped nanoglass for acute and diabetic wound therapies through anti-inflammatory and pro-angiogenic functions

Regeneration of pathological wounds,such as diabetic ulcers,poses a significant challenge in clinical settings,despite the widespread use of drugs.To overcome clinical side effects and complications,drug-free therapeutics need to be developed to promote angiogenesis while overcoming inflammation to restore regenerative events.This study presents a novel bioactive nanozyme based on cobalt-doped nanoglass(namely,CoNZ),which exhibits high enzymatic/catalytic activity while releasing therapeutic ions.Cobalt oxide“Co3O4”tiny crystallites produced in situ through a chemical reaction with H2O2 within CoNZ nanoparticles play a crucial role in scavenging ROS.Results showed that CoNZ-treatment to full-thickness skin wounds in mice significantly accelerated the healing process,promoting neovascularization,matrix deposition,and epithelial lining while reducing pro-inflammatory signs.Notably,CoNZ was highly effective in treating pathological wounds(streptozotocin-induced diabetic wounds).Rapid scavenging of ROS by CoNZ and down-regulation of pro-inflammatory markers while up-regulating tissue healing signs with proliferative cells and activated angiogenic factors contributed to the observed healing events.In vitro experiments involving CoNZ-cultures with macrophages and endothelial cells exposed to high glucose and ROS-generating conditions further confirmed the effectiveness of CoNZ.CoNZ-promoted angiogenesis was attributed to the release of cobalt ions,as evidenced by the comparable effects of CoNZ-extracted ionic medium in enhancing endothelial migration and tubule formation via activated HIF-1α.Finally,we compared the in vivo efficacy of CoNZ with the clinically-available drug deferoxamine.Results demonstrated that CoNZ was as effective as the drug in closing the diabetic wound,indicating the potential of CoNZ as a novel drug-free therapeutic approach.

Coherent supercontinuum generation in soft glass photonic crystal fibers

An overview of the progress on pulse-preserving, coherent, nonlinear fiber-based supercontinuum generation is presented. The context encompasses various wavelength ranges and pump sources, starting with silica photonic crystal fibers pumped with 1.0 μm femtosecond lasers up to chalcogenide step-index and microstructured fibers pumped from optical parametric amplifiers tuned to mid-infrared wavelengths. In particular, silica and silicatebased all-normal dispersion(ANDi) photonic crystal fibers have been demonstrated for pumping with femtosecond lasers operating at 1.56 μm with the recorded spectra covering 0.9–2.3 μm. This matches amplification bands of robust fiber amplifiers and femtosecond lasers. The review therefore focuses specifically on this wavelength range, discussing glass and nonlinear fiber designs, experimental results on supercontinuum generation up to the fundamental limit of oxide glass fiber transmission around 2.8 μm, and various limitations of supercontinuum bandwidth and coherence. Specifically, the role of nonlinear response against the role of dispersion profile shape is analyzed for two different soft glass ANDi fibers pumped at more than 2.0 μm. A spatio-temporal interaction of the fundamental fiber mode with modes propagating in the photonic lattice of the discussed ANDi fibers is shown to have positive effects on the coherence of the supercontinuum at pump pulse durations of 400 fs. Finally, the design and development of graded-index, nanostructured core optical fibers are discussed.In such structures the arbitrary shaping of the core refractive index profile could significantly improve the engineering flexibility of dispersion and effective mode area characteristics, and would be an interesting platform to further study the intermodal interaction mechanisms and their impact on supercontinuum coherence for subpicosecond laser pumped setups.

Sol-gel synthesis,properties and protein loading/delivery capacity of hollow bioactive glass nanospheres with large hollow cavity and mesoporous shell

Hollow nanospheres exhibit unique properties and find a wide interest in several potential applications such as drug delivery.Herein,novel hollow bioactive glass nanospheres(HBGn)with large hollow cavity and large mesopores in their outer shells were synthesized by a simple and facile one-pot ultrasound assisted sol-gel method using PEG as the core soft-template.Interestingly,the produced HBGn exhibited large hollow cavity with ~43 nm in diameter and mesoporous shell of ~37 nm in thickness and 7 nm pore size along with nanosphere size around 117 nm.XPS confirmed the presence of Si and Ca elements at the surface of the HBGn outer shell.Notably,HBGn showed high protein loading capacity(~570 mg of Cyto c per 1 g of HBGn)in addition to controlled protein release over 5 d.HBGn also demonstrated a good in vitro capability of releasing calcium(Ca^(2+):170 ppm)and silicate(SiO_(4)^(4-):78 ppm)ions in an aqueous medium over 2 weeks under physiological-like conditions.Excellent in vitro growth of bone-like hydroxyapatite nanocrystals was exhibited by HBGn during the soaking in SBF.A possible underlying mechanism involving the formation of spherical aggregates(coils)of PEG was proposed for the formation process of HBGn.

Influence of Fe_(2)O_(3) on the physical,structural and electrical properties of sodium lead borate glasses

The influence of adding Fe_(2)O_(3) at the expense of Na_(2)O in sodium lead borate glasses on the structural,physical and electrical properties have been investigated.Results obtained from Fourier transform infrared(FTIR)spectra indicated that Fe_(2)O_(3) plays an important role in converting three coordinated boron atoms[BO_(3)]to four coordinated boron atoms[BO4].The physical properties such as density and molar volume helped to evaluate the compact structure of the prepared glass samples due to presence of[BO4]groups.The increase of Fe_(2)O_(3)/Na_(2)O replacements led to increasing the microhardness values and decreasing the thermal expansion coefficients of the studied glasses.The increase of Fe_(2)O_(3)/Na_(2)O replacements generally decreased the AC conductivity.That decrease might be due to converting of the three coordinated boron atoms[BO_(3)]to four coordinated boron atoms[BO_(4)].Dielectric constants of the samples might be an indication of the distortion in the coordinated boron atoms.The obtained experimental data indicated the internal structure of glass network and the change of the structure of the samples from three[BO_(3)]to four coordinated boron atoms[BO4].

Utilization of iron oxide bearing pellets waste for preparing hard and soft ferromagnetic glass ceramics

About 8%of the imported iron oxide pellets burdens to Egypt are wasted.In this paper,broken pellets waste(BPW)is used as raw material for the preparation of hard magnetic glass ceramics(HMGC)as well as soft magnetic glass ceramics(SMGC).About 54 wt%and 37 wt%of BPW are used to prepare SMGC and HMGC,respectively.Differential thermal analysis(DTA)reveals two broad exothermic peaks for HMGC at 591℃and 697℃,whereas one exothermic peak at 820℃is detected for SMGC.X-ray diffraction(XRD)shows the crystallization of hematite as the sol phase in BPW,and meanwhile,Zn-ferrite and Ba-hexaferrite are identified in SMGC and HMGC,respectively.Transmission electron microscopy(TEM)reveals the crystallization of nanosize particles of~20 nm for SMGC and~12 nm for HMGC.Vibrating scanning magnetometer(VSM)reveals an increase in saturation magnetization from~1 emu/g for BPW to~77 emu/g for SMGC and 21 emu/g for HMGC.

Nanotherapeutics for regeneration of degenerated tissue infected by bacteria through the multiple delivery of bioactive ions and growth factor with antibacterial/angiogenic and osteogenic/odontogenic capacity

Therapeutic options are quite limited in clinics for the successful repair of infected/degenerated tissues.Although the prevalent treatment is the complete removal of the whole infected tissue,this leads to a loss of tissue function and serious complications.Herein the dental pulp infection,as one of the most common dental problems,was selected as a clinically relevant case to regenerate using a multifunctional nanotherapeutic approach.For this,a mesoporous bioactive glass nano-delivery system incorporating silicate,calcium,and copper as well as loading epidermal growth factor(EGF)was designed to provide antibacterial/pro-angiogenic and osteo/odontogenic multiple therapeutic effects.Amine-functionalized Cu-doped bioactive glass nanospheres(Cu-BGn)were prepared to be 50–60 nm in size,mesoporous,positive-charged and bone-bioactive.The Cu-BGn could release bioactive ions(copper,calcium and silicate ions)with therapeutically-effective doses.The Cu-BGn treatment to human umbilical vein endothelial cells(HUVEC)led to significant enhancement of the migration,tubule formation and expression of angiogenic gene(e.g.vascular endothelial growth factor,VEGF).Furthermore,the EGF-loaded Cu-BGn(EGF@Cu-BGn)showed pro-angiogenic effects with antibacterial activity against E.faecalis,a pathogen commonly involved in the pulp infection.Of note,under the co-culture condition of HUVEC with E.faecalis,the secretion of VEGF was up-regulated.In addition,the osteo/odontogenic stimulation of the EGF@Cu-BGn was evidenced with human dental pulp stem cells.The local administration of the EGF@Cu-BGn in a rat molar tooth defect infected with E.faecalis revealed significant in vivo regenerative capacity,highlighting the nanotherapeutic uses of the multifunctional nanoparticles for regenerating infected/damaged hard tissues.

Three-dimensional printing of biomaterials for bonetissue engineering: a review

Processing biomaterials into porous scaffolds for bone tissueengineering is a critical and a key step in defining and controlling their physicochemical,mechanical,and biological properties.Biomaterials such as polymers are commonlyprocessed into porous scaffolds using conventional processing techniques,e.g.,saltleaching.However,these traditional techniques have shown unavoidable limitations andseveral shortcomings.For instance,tissue-engineered porous scaffolds with a complexthree-dimensional(3D)geometric architecture mimicking the complexity of theextracellular matrix of native tissues and with the ability to fit into irregular tissue defectscannot be produced using the conventional processing techniques.3D printing hasrecently emerged as an advanced processing technology that enables the processing ofbiomaterials into 3D porous scaffolds with highly complex architectures and tunableshapes to precisely fit into irregular and complex tissue defects.3D printing providescomputer-based layer-by-layer additive manufacturing processes of highly precise andcomplex 3D structures with well-defined porosity and controlled mechanical propertiesin a highly reproducible manner.Furthermore,3D printing technology provides anaccurate patient-specific tissue defect model and enables the fabrication of a patientspecifictissue-engineered porous scaffold with pre-customized properties.