Earticle

Silver nanoparticles (AgNPs) exhibit broad spectrum antibacterial effect, but their cores after use can persist in the environment, which presents a toxic effect on humans. To address this issue, silver-based biomaterials are regarded as green alternatives to AgNPs. In this study, we used kraft lignin, a green and biodegradable polymer derived from wood biomass, to prepare an aminated lignin-silver complex (Ag@AL complex) as an alternative antibacterial agent. A facile approach for preparing aminated lignin (AL) was realized by the amination of kraft lignin using 2-chloroethylamine hydrochloride in water solvent. The nitrogen content of optimized AL was 4.37%. Ag(Ⅰ) could be captured and reduced to metallic Ag(0) by AL, thereby forming AgNPs on the surface of AL. Importantly, the obtained Ag@AL complex was proven to be an effective antibacterial agent against gram-positive (Bacillus cereus, Staphylococcus aureus) and gram-negative (Salmonella enterica) bacteria.

본 연구에서는 노, 유 복합 실버타운의 중요한 결정 요소로 지적되는 인구통계학적 특 성 및 경제와 경영적 요인 그리고 서울 근교 남양주 일원의 입지와 접근성에 대하여 분석 해 보고 그 방안을 제시하였다. 356명을 조사하여 다음과 같은 결과를 얻었다. 첫째, 일반적으로 모든 사람이 노, 유 복합 실버타운의 개념을 이해하였으며, 기존 실버 타운보다는 노, 유 복합 실버타운의 선호도가 높았다(평균 3.47). 둘째, 노인 주거복지시설 중 가장 살기 좋은 곳은 노, 유 복합 실버타운이 48.6%로 가 장 많았고, 실버타운도 44.1%로 높은 비율을 보였다. 노, 유 복합 실버타운의 입 주방식 은 임대형이 60.1%로 가장 많았다. 또한 적정 보증금과 월세는 1억 5000~2억 원 /30~40만 원이 36.5%로 가장 많았고, 입지가 좋은 교외 및 도심 녹지는 가장 선호하는 것으로 나타났다. 또한 모든 연령에서 도시근교가 가장 많았으나, 연령이 높을수록 도시 근교를 더 선호하였다. 셋째, 노인·유아 복합 실버타운의 관리요인으로는 첫 번째, 입주비용이 4.46으로 가장 중요한 것으로 나타났다. 두 번째는 재무구조의 건전성이었고, 세 번째는 직원의 자질이 었다. 넷째, 노, 유 복합 실버타운에서 가장 필요한 부대시설은 노, 유 가 함께 즐길 수 있는 운동/체육시설과 치료시설 그리고 여가활동인 사랑방과 취미강좌가 많았고, 또한 노, 유 가 함께 어울려서 할 수 있는 정규적인 프로그램도 일주일에 2회 정도가 매우 적당한 것 으로 나타났다.

In this study, the factors pointed out as important determinants for the complex silver town of the elderly and young children were studied. In other words, the demographic characteristics, economic and management factors, location and accessibility of Namyangju near Seoul were analyzed, and the measures were presented. 356 people were surveyed and the following results were obtained. First, in general, everyone understood the concept of a complex silver town of the elderly and young children. Complex silver towns for the elderly and young children were more popular (average 3.47) than existing silver towns. Second, among the residential welfare facilities for the elderly, the most desirable places to live were silver towns for the elderly and infants with 48.6%, and silver towns also showed a high rate with 44.1%. In terms of the move-in method desired by the elderly and young children in the complex silver town, the rental type was the most common at 60.1%. Also, in terms of appropriate deposit and monthly rent, 150-200 million won/300,000-400,000 won was the most at 36.5%, and green areas in the suburbs and within the city were most preferred in suitable locations. Third, as for the management factors for the elderly and young children's complex silver town, first, the move-in cost was found to be the most important at 4.46. The second was the soundness of the financial structure, and the third was the quality of employees.

A solution ink of a silver complex was prepared by dissolving silver neodecanoate in xylene up to a concentration of 25% silver (Ag-SI). Spun-coated Ag-SI films were thermally decomposed to metallic silver films with resistivity values of less than 4.5× 10?5 Ω·cm, after sintering above 160oC. In addition, a silver nanoparticle ink (Ag-PI) could be prepared by removing a large amount of neodecanoic acid from the Ag-SI by reduction with phenylhydrazine. The sintering temperature for Ag-PI with a resistivity below 1×10?4 Ω ·cm was reduced from 160oC to 130oC by using Ag-PI instead of Ag-SI. However, Ag-PI was rather unstable, as a precipitation occurred in one week at room temperature. Finally, Ag-SI was tested for production of a metallic film on a polyamide as a metal complex ink in a drop-on-demand ink jet printer. The results indicated that it would be very suitable as a conducting ink.

이핵 화합물, $Ag_2$[Phen]_2[S_2P(OPr)_2]_2$(Phen=1,10-phenanthroline; Pr=propyl)은 비스(디프로필디싸이오포스페이토) 은(|)화합물과 1,10 펜안트로린 리간드 반응에 의하여 합성되었고, 그 화합물 구조는 X-ray에 의하여 규명되었다. 두 디프로필디싸이오포스페이토 리간드는 두 개의 은 원자를 연결하여 팔각형 $Ag_2S_4P_2$ 고리를 형성하였고, 1,10-펜안트로린 리간드는 은 이온과 결합하여 사면체구조를 이루었다. Ag-S 결합거리는 2.471(1)와 2.567(1) ${\AA}$이었고, Ag-N 결합 거리는 2.3666(3)와 2.471(3) ${\AA}$이었다.

The dinuclear $Ag_2[Phen]_2[S_2P(OPr)_2]_2$(phen=1,10-phenanthroline; Pr=propyl), was prepared by the reaction of bis(dipropyldithiophosphato) silver(I) complex with 1,10-phenanthroline ligand, and its structure was determined by X-ray crystallography. The two dipropyldithiophosphato ligands each bridge two silver atoms to form an eight-membered $Ag_2S_4P_2$ ring, while the 1,10-phenanthroline molecule coordinates to a silver atom to complete the local tetrahedral geometry for the metal ion. The Ag-S bond distances are 2.559(1) and 2.567(1)${\AA}$, and the Ag-N bond distances are 2.366(3) and 2.471(3)${\AA}$.

A low temperature ($65^{\circ}C$) thermal deposition process was developed for depositing a silver coating on thermally sensitive polymeric substrates. This low temperature deposition was achieved by chemical reduction of a silver alkylcarbamate complex with latent reducing agent. The effects of acetol as a latent reducing agent for the silver 2-ethylhexylcarbamate (Ag-EHCB) complex and their blend solutions were investigated in terms of reducing mechanism, and the size and shape of silver nanoparticles (Ag-NPs) as a function of reduced temperature and time, and PVP stabilizer concentration were determined. Low temperature deposition was achieved by combining chemical reduction with thermal heating at $65^{\circ}C$. A range of polymer film, sheet and molding product was coated with silver at thicknesses of 100 nm. The effect of process parameters and heat treatment on the properties of silver coatings was investigated.

We present a method for chemically reducing silver alkylcarbamate complex with hydrazine to synthesize silver nanocolloids in an organic solvent using polyvinylpyrrolidone (PVP) as the stabilizer. To determine the optimal conditions for preparing stable silver colloids of controlled size and shape, the silver 2-ethylhexylcarbamate (Ag-EHCB) complex, PVP, hydrazine, and 2-propanol solvent concentrations in the reaction mixture were varied. The initial colloid has a mean particle diameter of 5-80 nm, and it exhibits an absorption band with various shapes in the UV region with a maximum near 420 nm. UV-vis spectroscopy, TEM, and X-ray diffraction techniques were used to investigate the formation and growth process of the metallic silver nanocolloids.

Controlled reduction of silver alkylcarbamate complexes with hydrogen gas was investigated as a facile synthetic method for high concentrations of silver nanocolloids in organic solvent. Polyvinylpyrrolidone (PVP) was used to stabilize the silver colloids obtained from the chemical reduction. To determine optimum conditions for preparation of the stable and controlled silver colloids with the narrowest particle size and distribution, a large number of experiments were carried out involving variations in the concentrations of the silver 2-ethylhexylcarbamate (Ag-EHCB) complex, PVP, and 2-propanol. The initial colloid had a mean particle diameter between 5$\sim$50 nm, as measured by transmission electron microscopy, and exhibited a sharp absorption band in the UV region with a maximum size near 420 nm. After treatment with a reducing agent, the colloids were characterized by ultraviolet-visible spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy.

We successfully decorated multi-wall carbon nanotubes (MWNTs) with silver by reacting Ag-NPs with thiolfunctionalized MWNT-SH. Ag alkylcarbamate complex was used as an Ag precursor. Uniform Ag-NPs (5-10 nm) were effectively prepared by microwaving within 60 s using 1-amino-4-methylpiperazine (AMP), which acts as a reaction medium, reducing agent, and stabilizer. The MWNTs were functionalized with 2-aminoethanethiol. Exploiting the chemical affinity between thiol and Ag-NPs, Ag-MWNT nanohybrids were obtained by spontaneous chemical adsorption of MWNT-SH to Ag through Ag-S bonds. The Ag-S-MWNTs were characterized by TGA, XRD, and TEM to confirm that Ag-NPs were uniformly decorated onto the MWNTs. The Ag-S-MWNTs were then employed as conducting filler in epoxy resin to fabricate electrically conducting polymer composites. The electrical properties of the composites were measured and compared with that containing MWNT-SH. The electrical conductivity of composites containing 0.4 wt % Ag-S-MWNT was four orders of magnitude higher than those containing same content of MWNT-SH, confirming Ag-S-MWNT as an effective conducting filler.

Complex membranes consisting of silver salt ($AgBF_4,\;AgCF_3SO_3,\;AgSbF_6,\;AgNO_3$) and poly(vinyl alcohol) (PVA) or crosslinked PVA (CPVA) were prepared and tested for the separation of propylene/propane mixtures. For the tested membranes, the complex membranes containing $AgBF_4$ exhibited the highest separation properties, i.e., approximately 20 GPU ($1 GPU=10^{-6}cm^3 (STP)/(cm^2 sec cmHg)$) and 100 of selectivity at 0.2 of silver mole fraction. The CPVA membranes containing silver salt always showed higher selectivity than PVA membranes, presenting silver ions coordinated to -CHO are more effective than those to -OH groups. The threshold silver concentration of CPVA membranes was lower than that of PVA membranes, which might be due to stronger interaction of silver ions with -CHO than that with -OH. The composition at which the selectivity is the highest did not significantly depend on the crosslinking, but did on the kind of silver salt.

The reduction behavior of silver ions to silver nanoparticles is an important research topic in polymer/silver salt complex membranes for facilitated olefin transport, because it has a significant effect on the long-term stability of membrane performance. In this study, the effects of solvent on the formation of silver nanoparticles and long-term membrane performance in polymer/silver salt complex membrane were investigated. This effect was assessed for the complexes of poly(N-vinyl pyrrolidone) $(PVP)/AgBF_{4}$ with the use of ionic liquid (IL), acetonitrile (ACN) and water as a solvent. Membrane performance test shows that long-term stability is strongly dependent on the kind of solvent and arranged: IL > ACN >> water.

The reduction behavior of silver ions to silver nanoparticles is an important topic in polymer/silver salt complex membranes to facilitate olefin transport, as this has a significant effect on the long-term performance stability of the membrane. In this study, the effects ofthe solvent type on the formation of silver nanoparticles, as well as the long-term membrane performance of a solid polymer/silver salt complex membrane were investigated. These effects were assessed for solid complexes of poly(N-vinyl pyrrolidone) $(PVP)/AgBF_4$, using either an ionic liquid (IL), acetonitrile (ACN) or water as the solvent for the membrane preparation. The membrane performance test showed that long-term stability was strongly dependent on the solvent type, which increased in the following order: IL > ACN >> water. The formation of silver nanoparticles was more favorable with the solvent type in the reverse order, as supported by UV-visible spectroscopy. The poor stability of the $(PVP)/AgBF_4$ membrane when water was used as the solvent might have been due to the small amount of water present in the silver-polymer complex membranes actively participating in the reduction reaction of the silver ions into silver nanoparticles. Conversely, the higher stability of the $(PVP)/AgBF_4$, membrane when an IL was used as the solvent was attributable to the cooperative coordination of silver ions with the IL, as well as with the polymer matrix, as confirmed by FTIR spectroscopy.

Silver nanoparticles have been synthesized by liquid-phase and alcohol reduction methods. Silver-doped silica-complex nanoparticles were prepared using a sol-gel process. The formation, structure, morphology, and particle size of the nanoparticles have been studied using several techniques. Silver nanoparticles of size of 30-40 nm were formed successfully by alcohol reduction. TEM images show that both the concentration and the molecular weight of polyvinyl pyrrolidone (PVP) considerably affect the size of the emerging silver nanoparticles. The number of silver-doped silica-complex particles increased by a mercapto-group treatment that showed a narrower size distribution than that of silica treated with amino groups. The silver/polyester and silver-doped silica/polyester masterbatch chips showed excellent antibacterial activity against Staphylococcus aureus and Escherichia coli.

Ag+ 이온과 Ca2+ 이온으로 교환하고 진공 탈수한 제올라이트 A에 브롬을 흡착한 결정 구조(a=12.234(1) Å)를 입방공간군 Pm3m을 사용하여 단결정 X-선 회절법으로 구조를 해석하였다. 결정은 AgNo3와 Ca(No3)2의 몰 비를 1:150으로 하고 농도를 0.05M으로 한 혼합용액을 사용하여 흐름법으로 3일간 이온 교환하였다. 그 결정을 360℃에서 2 ×10-6 Torr하에서 2일간 진공 탈수한 다음 약 180 Torr의 브롬 기체로 24℃에서 20분간 처리하였다. 이 결정 구조는 Full-matrix 최소자승법 정밀화 계산에서 I>3o(I)인 반사 90개를 써서 R1=0.111, R2=0.101까지 얻었다. 이 구조에서 3.1개의 Ag+이온과 4.45개의 Ca2+ 이온이 6-링 산소와 결합하면서 두개의 서로 다른 3회 회전축 상에 위치하고 있었고 단위 세포당 총 여섯 분자의 브롬이 흡착되었다. 각 브롬 분자는 골격 구조의 산소 이온과 전하 이동 작용에 의해 결합하고 있었다(Br-Br-O=171(2), O-Br=3.25(6) Å; Br-Br=2.61(8) Å.

The crystal structure of a bromine sorption complex of vacuum-dehydrated Ag+ and Ca2+ exchanged zeolite A(a=12,234(1) Å) has been determined by single-crystal X-ray diffraction methods in the cubic space group Pm3m. The crystal was prepared by flow method using exchange solution in which mole ratio of AgNo3 and Ca(NO3)2 was 1:150 with a total concentration of 0.05M. The crystal was dehydrated at 360℃ and 2 ×10-6 Torr for 2days, followed by exposure to 180 Torr of Br2 vapor for 20min. full-matrix least-squares refinements converged to the final error indices of R1=0.111 and R2=0.101 using 90 reflections for which I>3o(I). About 3.1 Ag+ ions and 4.45 Ca2+ ions lie on the two crystallographically nonequivalent three-fold axes associated with 6-ring oxygens. A total of six bromine molecules are sorbed per unit cell. Each bromine molecule approaches a framework oxide ions axially (Br-Br-O=171(2)', O-Br=3.25(6) Å; and Br-Br=2,61(8) Å by a charge-transfer interaction.