这项工作是卞的同时，陈，王均博士来访进行学生在美国林务局，林产品实验室（FPL），麦迪逊，并在朱的政府官方时间。这项工作是部分由美国农业部农业和食品研究计划（AFRI）竞争性赠款（2011-67009-20056号），中国国家林业局（项目编号:2015-4-54），国家自然科学基金资助中国（项目编号:31470599），中国广州精英项目，以及中国奖学基金。从这些项目的资金在FPL可能做边，陈，王来访的任命。

注意:漂白桉木浆（BEP），并从商业渠道漂白混合阔叶牛皮浆（UMHP）纤维作为原料用于生产CNC和CNF。购买的商业马来酸被用于水解。水解条件为:60重量％的酸浓度，在100℃进行60分钟和120分钟120℃（在大气压下没有沸点），对BEP和UMHP分别。 1.浓二元酸溶液的制备<ol><li>热40毫升在加热板上于约85℃的液体甘油浴去离子在多颈烧瓶（DI）水。 </li><li>添加60克无水马来酸到烧瓶中，使用磁力搅拌的60％（重量）溶液。使用酸溶液的先前报道15的密度，计算所需的水和酸量为使得在指定的质量浓度的酸溶液。 </li><li>加热该溶液到解100或120℃sired水解温度（不沸腾由于高二元酸的浓度）。 </li></ol> 2.水解反应<ol><li>一旦该酸溶液是在温度，添加的BEP或UMHP纤维为10克烘干（OD）与连续搅拌80毫升二羧酸溶液（1.1）。 <ol><li>通过加入80℃的去离子水160毫升终止水解之前采取在60分钟的规定的反应时间结束时的酸水解产物（约2毫升）的等分试样。 </li></ol></li><li>稀释0.5毫升抽样水解糖和酸浓度分析。 15观察结晶发生，同时咕咕至室温剩余水解产物样品。 </li><li>通过在布氏漏斗用滤纸真空过滤分离从水解纸浆的水解产物。 注:此分离所需要的温度下降之前相当快发生，而酸轧花结晶出来的溶液。由于从酸溶液中高离子强度，CNC的产生的水解凝聚和留在FCSR残差。约该酸的80-90％会与滤液中除去。 </li></ol> 3.数控分离<ol><li>从洗净2节使用去离子水滤出的固体并稀释至用去离子水大约1％的总固体。离心滤液在11960×g离心10分钟。 </li><li>滗掉上清液。重复使用新鲜的DI水，直到上清液是浑浊的洗涤和过滤过程。浊度表示该溶液的离子强度已经降至足够使CNC分散并开始变得胶体。 </li><li>混合与结算水解浆（2.3）浑浊的上清液。透析的透析袋（MWCO 14 kDa）的使用去离子水，直到该液体的导电率接近于DI水的混合物中。采用电导仪测量电导率。 </li><li>离心机在3500×g离心10分钟，得到在水相中数控分散体中的透析样品。保留沉淀相， 即 FCSR，为CNF生产。 </li><li>确定来自数控使用是COD方法分散液中的测定量的数控收率先前描述3,18。 </li></ol> 4.生产CNF <ol><li>分离CNC分散后确定沉淀FCSR由重力测量产量。干燥在105℃的FCSR并测量FCSR相对BEP或UMHP纤维使用的初始烘干重的烘箱干燥重量。 </li><li>通过连续传递悬浮液3次通过200微米的孔室随后2次通过87微米的孔室，所有在100兆帕机械原纤化在0.5％的纤维悬浮液的FCSR。 </li></ol> 5.原子力显微镜（AFM）成像<ol><li>超声处理约0.01％（重量）CNC或CNF小号uspensions 2分钟。沉积分散悬浮液的云母基板上的下降。风干在环境温度下沉积的悬浮液中。 </li><li>取风干的CNC和的CNFs的AFM图像中振动使用制造商的协议轻敲模式。分析使用商业软件获得的直径和长度分布大约100个独立的CNC或在的CNFs原子力显微镜图像。 </li></ol> 6.傅立叶变换推断（FTIR）测量<ol><li>使用商业红外分光光度计通用的衰减，全反射（ATR）探头来分析产生的CNC和CNF样品与原BEP和UMHP纤维识别酯基团一起。 </li><li>记录样品的吸收光谱在450之间的波长范围内- 4000厘米-1的4 -1和4扫描每个样品的分辨率。 </li></ol> 7.电导滴定<ol><li>使用电导滴定至QUAntify羧基样品组内容源于酯化由二羧酸。 </li><li>添加数控或CNF悬浮液与50mg（OD）的CNC或的CNFs的成1的120毫升的20mM NaCl溶液。通过以30秒的间隔将约0.2毫升2mM的NaOH溶液滴定该混合物。 </li><li>测量使用电导计的导电性。加入NaOH过程中找到的电导率曲线拐点（最低点）。 </li><li>计算基于所消耗的NaOH相对于使用以下等式其中c是NaOH溶液（摩尔/升）浓度的拐点上的羧基量（mmol / L）的量，v是加入NaOH溶液体积（毫升），m为CNC控制器或的CNFs的外径重量（克质量）。 <img alt="方程" src="/files/ftp_upload/55079/55079eq1.jpg" /></li></ol> 8. CNC和CNF热稳定性测定<ol><li>进行的t热降解测量他CNC和CNF通过热重分析（TGA）的样品。 </li><li>清除用高纯度的氮气流炉以20毫升/分钟，以防止任何不希望的氧化分解。干燥的样品在50℃下进行测试之前4小时。在干重使用的5毫克样品尺寸。 </li><li>记录样品的重量为炉温以10℃/分钟的加热速率上升，从室温至600℃。 </li><li>正常化由初始重量所测量的重量损失。 </li><li>进行CNC和CNF样品的单独的热稳定性测试中，在105℃的烘箱。后4小时和24小时通过常规的摄影记录样品的颜色变化。 </li></ol> 9. X射线衍射<ol><li>按冻干数控或CNF样品在180兆帕如前所述使粒料。 38 - 5行为广角上使用在102θ范围内的X射线衍射装置的Cu-Kα射线的粒料的X射线衍射测量在°0.02°步骤。 </li><li>计算使用西格尔方法19的粒料的结晶度指数（CRI）（无基线减法）。 </li></ol>

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陈和朱是使用CNC和CNF生产二元酸的美国专利申请的共同发明人。

从马来酸水解数控样品的较厚数控直径导致了中等平均纵横比7.24和8.53，对于CNC控制器从分别的BEP和UMHP，尽管它们的长的长度，如上所述。所述的CNFs具有比各自的CNC较长的长度和更薄的直径，这就造成了13.9和19.0纵横比大，为的CNC从分别的BEP和UMHP，都大得多。它可以使用剧烈的机械原纤化，以减少CNF直径来提高宽高比如在本研究中微流化所用的压力是相当低的。 木质素颗粒?...

经济的可持续发展，不仅需要使用的是可再生和可生物降解原料，但也使用绿色环保的制造技术，生产出各种从这些可再生原料的生物制品和生化的。纤维素纳米材料，如纤维素纳米晶体（CNC）和纤维素纳米原纤维（CNF），从可再生的木质纤维素生产可生物降解的和具有适于显影的范围内的生物制品1,2的独特的机械和光学性能。不幸的是，用于制造纤维素纳米材料的现有技术或者是能量密集型的使用纯机械开纤或环境不可持续由于非回收或处理的化学品，回收不足时，例如使用浓无机酸水解过程3-8或氧化方法9-当如11。此外，氧化的方法也可以产生对环境有毒的COMPO与木质纤维素反应unds。因此，发展绿色制造技术用于生产纤维素纳米材料是非常重要的，充分利用丰富的和可再生的材料 - 木质纤维素。 用酸水解，溶解半纤维素和解聚纤维素是用于制造纤维素纳米材料的有效途径。固体酸已被用于糖产量从纤维素与缓和酸回收12,13的优点。用浓无机酸以前的研究表明，低级酸浓度提高数控收率和结晶3,5。这表明，强酸可能损坏纤维素结晶而温和的酸水解可能是通过综合生产和数控与CNF 3,14的办法提高了性能和纤维素纳米材料的产量。在这里，我们使用浓度固体二元酸水解全国生产记录的方法ËCNC与CNF 15一起。这些二羧酸具有在低温或环境温度下的溶解度低，因此，它们可通过成熟结晶技术很容易地回收。它们也具有在高温下便于浓酸水解未经煮沸或使用压力容器良好的溶解性。因为这些酸也有较高的pKa比用于数控生产典型的无机酸，它们的使用效果良好的数控结晶度，尽管低级数控产率，与纤维状的纤维素固体残余物的显着量（FCSR或部分水解的纤维）剩余由于不完整的纤维素解聚。该FCSR可使用低能量输入，通过后续的机械开纤生产CNF。因此，与使用无机酸纤维素损失为糖是最小的。 它公知的是羧酸可以通过费- Speier酯化16酯化纤维素。施加二羧酸与纤维素可导致半酸未交联的酯17（或羧化），以产生羧基化CNC和CNF为我们证实15先前。这里介绍的方法可以产生羧基和热稳定CNF和数控，这也是无论从漂白或未漂白纸浆高度结晶，同时具有相对简单和高化学品回收和使用低能源投入。

<table border="0" cellpadding="0" cellspacing="0" width="1222">
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:349px;">Bleached eucalypus pulp&#160;</td>
			<td style="width:327px;">Aracruz Cellulose</td>
			<td style="width:248px;"></td>
			<td style="width:299px;"></td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;width:349px;">Unbleached mixed hardwood kraft pulp&#160;</td>
			<td>International Paper&#160;</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="26">
			<td height="26" style="height:27px;">Maleic acid</td>
			<td>Sigma-Aldrich</td>
			<td>M0375-1KG/CAS110-16-7</td>
			<td style="width:299px;">Powder; assay: 99.0%(HPLC)</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Glycerol</td>
			<td>Sigma-Aldrich</td>
			<td>G5516-4L/CAS56-81-5</td>
			<td></td>
		</tr>
		<tr height="37">
			<td height="37" style="height:38px;">Sodium hydroxide</td>
			<td>Fisher Scientific</td>
			<td style="width:248px;">S318-500/CAS1310-73-2, 497-19-8</td>
			<td>Certified ACS</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;">Sodium chloride</td>
			<td>Mallinckrodt</td>
			<td>7581-12/CAS7647-14-5</td>
			<td>Crystal,AR</td>
		</tr>
		<tr height="41">
			<td height="41" style="height:42px;">Cupriethylenediamine solution</td>
			<td>GFS Chemicals</td>
			<td>E32103-1L/CAS14552-35-3</td>
			<td style="width:299px;">1M, for determination of solution viscosity of pulps</td>
		</tr>
		<tr height="24">
			<td height="24" style="height:25px;">Acetone</td>
			<td>Fisher Scientific</td>
			<td>A18-500/CAS67-64-1</td>
			<td>Certified ACS</td>
		</tr>
		<tr height="40">
			<td height="40" style="height:40px;">Accu-TestTM Vials for COD Testing</td>
			<td>Bioscience,Inc.</td>
			<td>01-215-28</td>
			<td style="width:299px;">COD testing for 20 to 900mg/L standard range concentration</td>
		</tr>
		<tr height="23">
			<td height="23" style="height:23px;">Heating plate</td>
			<td>IKA</td>
			<td></td>
			<td>Mode: C-MAD HS7 digital</td>
		</tr>
		<tr height="29">
			<td height="29" style="height:30px;">Magnetic stir bar</td>
			<td>ACE Glass</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="29">
			<td height="29" style="height:30px;">Pyrex three-neck round-bottom flask</td>
			<td>Sigma-Aldrich</td>
			<td>CLS4965B500-1EA</td>
			<td></td>
		</tr>
		<tr height="38">
			<td height="38" style="height:39px;">Dialysis tubing cellulose membrane</td>
			<td>Sigma-Aldrich</td>
			<td>D9402-100FT</td>
			<td style="width:299px;">Typical molecular weight cut-off = 14000</td>
		</tr>
		<tr height="22">
			<td height="22" style="height:23px;">Disposable aluminum dishes</td>
			<td>Sigma-Aldrich</td>
			<td>Z154857-1PAK</td>
			<td>Circles, 60mm</td>
		</tr>
		<tr height="19">
			<td height="19" style="height:19px;">Disintegrator</td>
			<td>Testing Machines Inc.(TMI)</td>
			<td></td>
			<td style="width:299px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Microfluidizer</td>
			<td>Microfluidics Corporation</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Sonicator</td>
			<td>Qsonica LLC.</td>
			<td></td>
			<td>Mode: 3510R-MT, 50-60 Hz,180 W</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Zeta potential analyzer</td>
			<td>Brookhaven Instruments Corporation</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">FTIR</td>
			<td>PerkinElmer</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">Conductometric titrator</td>
			<td>Yellow Springs Instrument (YSI)</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">TGA analyzer</td>
			<td>PerkinElmer</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">X-ray diffractometer</td>
			<td>Bruker Corporation</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">AFM imging&#160;</td>
			<td>AFM Workshop</td>
			<td></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;">SEM imaging</td>
			<td>Carl Zeiss</td>
			<td></td>
			<td></td>
		</tr>
	</tbody>
</table>

green and low-cost production of thermally stable and carboxylated cellulose nanocrystals and nanofibrils using highly recyclable dicarboxylic acids

这里，我们证明成本潜在的低使用高度可回收的二固体酸的漂白桉木浆（BEP）和未漂白混合阔叶牛皮浆（UMHP）纤维高的热稳定性和羧基化纤维素纳米晶（CNC控制器）和纳米原纤维（CNF）的绿色生产。典型的操作条件为50的酸浓度 - 70％（重量）在100℃下60分钟和120分钟120℃（在大气压下没有沸点），对BEP和UMHP分别。所得的CNC具有较高的热降解温度比其相应的原料纤维和羧酸基含量为0.2 - 0.4毫摩尔/克。低强度（1.0高pKa值 - 3.0）有机酸也导致约为239两种长度更长的CNC - 336纳米和更高的结晶度比使用的CNC无机酸产生的。纤维素损失糖是最小的。从二羧酸水解纤维状的纤维素固体残余物（FCSR）被用来通过与低能量输入随后的机械颤动产生羧基化的CNFs。

与进料酸水解纤维对应SEM图像沿着从BEP和UMHP CNC和CNF的典型的AFM图像示于图1和2。该图像清楚地表明在纤维长度的大幅度减少通过酸水解，在纤维直径变化最小（ 图1a与1b中的比较，以及图2a与2b）的 。缩短的纤维长度也被聚合的水解纤维的测量纤维素度（DP）的反射。 DP分别降低从1021和806至319和342，对于BEP和UMHP。与典型?...

Watch this Scientific Journal Video about Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids at JoVE.c

Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids

在这里，我们证明了使用高度可回收固体二羧酸高度热稳定的和羧化的纤维素纳米晶体（CNC）和纳米原纤维（CNF）的绿色和可持续的生产的新方法。

热稳定和羧基化纤维素纳米晶和纳米原纤维使用高度可回收的二元羧酸绿色和低成本生产

Here we demonstrate potentially low cost and green productions of high thermally stable and carboxylated cellulose nanocrystals (CNCs) and nanofibrils ...

green-low-cost-production-thermally-stable-carboxylated-cellulose

Research

JoVE Journal

Chemistry

11.8K 次观看.  Nanjing Forestry University. 在这里，我们证明了使用高度可回收固体二羧酸高度热稳定的和羧化的纤维素纳米晶体（CNC）和纳米原纤维（CNF）的绿色和可持续的生产的新方法。 

视频: Green and Low-cost Production of Thermally Stable and Carboxylated Cellulose Nanocrystals and Nanofibrils Using Highly Recyclable Dicarboxylic Acids

Seeded Synthesis of CdSe/CdS Rod and Tetrapod Nanocrystals

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded synthesis strategy is used in which spherical seeds of CdSe are prepared first using a hot-injection technique. By controlling the crystal structure of the seed to be either wurtzite or zinc-blende, the subsequent hot-injection growth of CdS off of the seed results in either a rod-shaped or tetrapod-shaped nanocrystal, respectively. The phase and morphology of the synthesized nanocrystals are confirmed using X-ray diffraction and transmission electron microscopy, demonstrating that the nanocrystals are phase-pure and have a consistent morphology. The extinction coefficient and quantum yield of the synthesized nanocrystals are calculated using UV-Vis absorption spectroscopy and photoluminescence spectroscopy. The rods and tetrapods exhibit extinction coefficients and quantum yields that are higher than that of the bare seeds. This synthesis demonstrates the precise arrangement of materials that can be achieved at the nanoscale by using a seeded synthetic approach.

A protocol for the seeded synthesis of rod-shaped and tetrapod-shaped multicomponent nanostructures consisting of CdS and CdSe is presented.

硒化镉/硫化镉棒和纳米四脚合成种子

We demonstrate a method for the synthesis of multicomponent nanostructures consisting of CdS and CdSe with rod and tetrapod morphologies. A seeded ...

科研

化学

Qualitative Identification of Carboxylic Acids, Boronic Acids, and Amines Using Cruciform Fluorophores

Molecular cruciforms are X-shaped systems in which two conjugation axes intersect at a central core. If one axis of these molecules is substituted with electron-donors, and the other with electron-acceptors, cruciforms&#39; HOMO will localize along the electron-rich and LUMO along the electron-poor axis. This spatial isolation of cruciforms&#39; frontier molecular orbitals (FMOs) is essential to their use as sensors, since analyte binding to the cruciform invariably changes its HOMO-LUMO gap and the associated optical properties. Using this principle, Bunz and Miljani&#263; groups developed 1,4-distyryl-2,5-bis(arylethynyl)benzene and benzobisoxazole cruciforms, respectively, which act as fluorescent sensors for metal ions, carboxylic acids, boronic acids, phenols, amines, and anions. The emission colors observed when these cruciform are mixed with analytes are highly sensitive to the details of analyte&#39;s structure and - because of cruciforms&#39; charge-separated excited states - to the solvent in which emission is observed. Structurally closely related species can be qualitatively distinguished within several analyte classes: (a) carboxylic acids; (b) boronic acids, and (c) metals. Using a hybrid sensing system composed from benzobisoxazole cruciforms and boronic acid additives, we were also able to discern among structurally similar: (d) small organic and inorganic anions, (e) amines, and (f) phenols. The method used for this qualitative distinction is exceedingly simple. Dilute solutions (typically 10-6 M) of cruciforms in several off-the-shelf solvents are placed in UV/Vis vials. Then, analytes of interest are added, either directly as solids or in concentrated solution. Fluorescence changes occur virtually instantaneously and can be recorded through standard digital photography using a semi-professional digital camera in a dark room. With minimal graphic manipulation, representative cut-outs of emission color photographs can be arranged into panels which permit quick naked-eye distinction among analytes. For quantification purposes, Red/Green/Blue values can be extracted from these photographs and the obtained numeric data can be statistically processed.

Cross-conjugated cruciform fluorophores based on 1,4-distyryl-2,5-bis(arylethynyl)benzene and benzobisoxazole nuclei can be used to qualitatively identify diverse Lewis acidic and Lewis basic analytes. This method relies on the differences in emission colors of the cruciforms that are observed upon analyte addition. Structurally closely related species can be distinguished from each other.

使用十字型荧光基团的羧酸，硼酸，胺的定性鉴别

Molecular cruciforms are X-shaped systems in which two conjugation axes intersect at a central core. If one axis of these molecules is substituted with ...

Thin-layer Chromatographic (TLC) Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the chromatograms to microbial suspensions (e.g. fungi or bacteria in broth or agar), allowing time for the microbes to grow in a humid environment, and visualizing zones with no microbial growth.&#160;The effectiveness of this screening method, known as bioautography, depends on both the quality of the chromatographic separation and the care taken with microbial culture conditions.&#160;This paper describes standard protocols for TLC and contact bioautography&#160;with a novel application to amino acid-fermenting bacteria. The extract is separated on flexible (aluminum-backed) silica TLC plates, and bands are visualized under ultraviolet (UV) light.&#160;Zones are cut out and incubated face down onto agar inoculated with the test microorganism.&#160;Inhibitory bands are visualized by staining the agar plates with tetrazolium red.&#160;The method is applied to the separation of red clover (Trifolium pratense cv. Kenland) phenolic compounds and their screening for activity against Clostridium sticklandii, a hyper ammonia-producing bacterium (HAB) that is native to the bovine rumen.&#160;The TLC methods apply to many types of plant extracts&#160;and other bacterial species (aerobic or anaerobic), as well as fungi, can be used as test organisms if culture conditions are modified to fit the growth requirements of the species.

Thin-layer Chromatographic TLC Separations and Bioassays of Plant Extracts to Identify Antimicrobial Compounds

Methods are described for thin-layer chromatographic (TLC) separation of plant extracts and contact bioautography to identify antibacterial metabolites. The methods are applied to the screening of red clover phenolic compounds inhibiting hyper&#160;ammonia-producing bacteria (HAB) native to the bovine rumen.

薄层色谱（TLC）分离和植物提取物的生物测定识别抗菌化合物

A common screen for plant antimicrobial compounds consists of separating plant extracts by paper or thin-layer chromatography (PC or TLC), exposing the ...

Characterization, Quantification and Compound-specific Isotopic Analysis of Pyrogenic Carbon Using Benzene Polycarboxylic Acids (BPCA)

Fire-derived, pyrogenic carbon (PyC), sometimes called black carbon (BC), is the carbonaceous solid residue of biomass and fossil fuel combustion, such as char and soot. PyC is ubiquitous in the environment due to its long persistence, and its abundance might even increase with the projected increase in global wildfire activity and the continued burning of fossil fuel. PyC is also increasingly produced from the industrial pyrolysis of organic wastes, which yields charred soil amendments (biochar). Moreover, the emergence of nanotechnology may also result in the release of PyC-like compounds to the environment. It is thus a high priority to reliably detect, characterize and quantify these charred materials in order to investigate their environmental properties and to understand their role in the carbon cycle.
Here, we present the benzene polycarboxylic acid (BPCA) method, which allows the simultaneous assessment of PyC&#39;s characteristics, quantity and isotopic composition (13C and 14C) on a molecular level. The method is applicable to a very wide range of environmental sample materials and detects PyC over a broad range of the combustion continuum, i.e., it is sensitive to slightly charred biomass as well as high temperature chars and soot. The BPCA protocol presented here is simple to employ, highly reproducible, as well as easily extendable and modifiable to specific requirements. It thus provides a versatile tool for the investigation of PyC in various disciplines, ranging from archeology and environmental forensics to biochar and carbon cycling research.

Characterization, Quantification and Compound-specific Isotopic Analysis of Pyrogenic Carbon Using Benzene Polycarboxylic Acids BPCA

We present the benzene polycarboxylic acid (BPCA) method for assessing pyrogenic carbon (PyC) in the environment. The compound-specific approach uniquely provides simultaneous information about the characteristics, quantity and isotopic composition (13C and 14C) of PyC.

表征，气相炭用苯聚羧酸的定量和特定化合物同位素分析（BPCA）

Fire-derived, pyrogenic carbon (PyC), sometimes called black carbon (BC), is the carbonaceous solid residue of biomass and fossil fuel combustion, such as ...

Preparation of Biopolymer Aerogels Using Green Solvents

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m2/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm3), high specific surface area (350 - 500 m2/g) and pore volume (3 - 7 cm3/g for pore sizes less than 150 nm).

A new way for the production of biopolymer-based aerogels by carbon dioxide (CO2) induced gelation is shown. The technique utilizes pressurized carbon dioxide (5 MPa) for the production of biopolymer hydrogels and supercritical CO2 (12 MPa) to convert gels into aerogels. The only solvents needed besides CO2 are water and ethanol.

生物聚合物气凝胶制备使用绿色溶剂

Although the first reports on aerogels made by Kistler1 in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers ...

Highly Stable, Functional Hairy Nanoparticles and Biopolymers from Wood Fibers: Towards Sustainable Nanotechnology

Nanoparticles, as one of the key materials in nanotechnology and nanomedicine, have gained significant importance during the past decade. While metal-based nanoparticles are associated with synthetic and environmental hassles, cellulose introduces a green, sustainable alternative for nanoparticle synthesis. Here, we present the chemical synthesis and separation procedures to produce new classes of hairy nanoparticles (bearing both amorphous and crystalline regions) and biopolymers based on wood fibers. Through periodate oxidation of soft wood pulp, the glucose ring of cellulose is opened at the C2-C3 bond to form 2,3-dialdehyde groups. Further heating of the partially oxidized fibers (e.g., T = 80 &#176;C) results in three products, namely fibrous oxidized cellulose, sterically stabilized nanocrystalline cellulose (SNCC), and dissolved dialdehyde modified cellulose (DAMC), which are well separated by intermittent centrifugation and co-solvent addition. The partially oxidized fibers (without heating) were used as a highly reactive intermediate to react with chlorite for converting almost all aldehyde to carboxyl groups. Co-solvent precipitation and centrifugation resulted in electrosterically stabilized nanocrystalline cellulose (ENCC) and dicarboxylated cellulose (DCC). The aldehyde content of SNCC and consequently surface charge of ENCC (carboxyl content) were precisely controlled by controlling the periodate oxidation reaction time, resulting in highly stable nanoparticles bearing more than 7 mmol functional groups per gram of nanoparticles (e.g., as compared to conventional NCC bearing &#60;&#60; 1 mmol functional group/g). Atomic force microscopy (AFM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM) attested to the rod-like morphology. Conductometric titration, Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), dynamic light scattering (DLS), electrokinetic-sonic-amplitude (ESA) and acoustic attenuation spectroscopy shed light on the superior properties of these nanomaterials.

Synthesis schemes to prepare highly stable wood fiber-based hairy nanoparticles and functional cellulose-based biopolymers have been detailed.

高稳定性，功能性毛纳米粒子和木纤维生物聚合物:迈向可持续纳米技术

Nanoparticles, as one of the key materials in nanotechnology and nanomedicine, have gained significant importance during the past decade. While ...

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) hydrogen fuel cells. Researchers seeking to develop such systems require a method of measuring the generated hydrogen. Herein, we describe a simple, low-cost, and robust method to measure the hydrogen generated from the reaction of solids with aqueous solutions. The reactions are conducted in a conventional one-necked round-bottomed flask placed in a temperature controlled water bath. The hydrogen generated from the reaction in the flask is channeled through tubing into a water-filled inverted measuring cylinder. The water displaced from the measuring cylinder by the incoming gas is diverted into a beaker on a balance. The balance is connected to a computer, and the change in the mass reading of the balance over time is recorded using data collection and spreadsheet software programs. The data can then be approximately corrected for water vapor using the method described herein, and parameters such as the total hydrogen yield, the hydrogen generation rate, and the induction period can also be deduced. The size of the measuring cylinder and the resolution of the balance can be changed to adapt the setup to different hydrogen volumes and flow rates.

The study of methods to generate on-demand hydrogen for fuel cells continues to grow in importance. However, systems to measure hydrogen evolution from the reaction of chemicals with water can be complicated and expensive. This article details a simple, low-cost, and robust method to measure the evolution of hydrogen gas.

一种简单，低成本和强大的系统来测量氢气与水溶液化学反应放出的音量

There is a growing research interest in the development of portable systems which can deliver hydrogen on-demand to proton exchange membrane (PEM) ...

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable low-valent-phosphorus-containing compound acts as a useful P+ transfer agent. Unlike traditional methods employed to access low-coordinate phosphorus species which usually require pyrophoric phosphorus-containing precursors (white phosphorus, Tris(trimethylsilyl)phosphine, etc.), or harsh reducing agents (alkali metals, potassium graphite, etc.), the current approach does not involve pyrophoric or explosive reagents and can be done on large scales (&#62;20 g) in excellent yields by undergraduates with basic air-free synthetic training. The bromide counter ion is readily exchanged with other anions such as tetraphenyl borate (described herein) using typical salt metathesis reagents to obtain materials with desired properties and reactivities. The versatility of this P+ transfer approach is exemplified by the reactions of these triphosphenium precursors with an N-heterocyclic carbene and an anionic bisphosphine, each of which readily displace the neutral bisphosphine to give an NHC-stabilized phosphorus(I) cation and a phosphorus(I) containing zwitterion, respectively.

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of PhosphorusI

The synthesis of a triphosphenium bromide salt is described and its use as a P+ transfer agent is outlined by reactions with an N-heterocyclic carbene and an anionic bisphosphine, yielding an NHC-stabilized P(I) cation and a P(I) containing zwitterion, respectively.

制备及反应性的Triphosphenium溴化物盐:磷方便稳定来源（I）

We present herein the optimized synthesis of a triphosphenium bromide salt. Apart from being a versatile metathesis reagent, this unusually stable ...

Synthesis of Core-shell Lanthanide-doped Upconversion Nanocrystals for Cellular Applications

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical properties, which allow for the absorption of near-infrared (NIR) light and can subsequently convert it into multiplexed emissions that span over a broad range of regions from the UV to the visible to the NIR. This article presents detailed experimental procedures for high-temperature co-precipitation synthesis of core-shell UCNs that incorporate different lanthanide ions into nanocrystals for efficiently converting deep-tissue penetrable NIR excitation (808 nm) into a strong blue emission at 480 nm. By controlling the surface modification with biocompatible polymer (polyacrylic acid, PAA), the as-prepared UCNs acquires great solubility in buffer solutions. The hydrophilic nanocrystals are further functionalized with specific ligands (dibenzyl cyclooctyne, DBCO) for localization on the cell membrane. Upon NIR light (808 nm) irradiation, the upconverted blue emission can effectively activate the light-gated channel protein on the cell membrane and specifically regulate the cation (e.g., Ca2+) influx in the cytoplasm. This protocol provides a feasible methodology for the synthesis of core-shell lanthanide-doped UCNs and subsequent biocompatible surface modification for further cellular applications.

A protocol is presented for the synthesis of core-shell lanthanide-doped upconversion nanocrystals (UCNs) and their cellular applications for channel protein regulation upon near-infrared (NIR) light illumination.

核壳镧系掺杂转换纳米晶的合成及其在蜂窝中的应用

Lanthanide-doped upconversion nanocrystals (UCNs) have attracted much attention in recent years based on their promising and controllable optical ...

Fabrication of Spherical and Worm-shaped Micellar Nanocrystals by Combining Electrospray, Self-assembly, and Solvent-based Structure Control

Micellar nanocrystals (micelles with encapsulated nanocrystals) have become an emerging major class of nanobiomaterials. We describe a method of fabricating micellar nanocrystals based on combining top-down electrospray, bottom-up self-assembly, and solvent-based structure control. This method involves first using electrospray to generate uniform ultrafine liquid droplets, each of which functions as a micro-reactor in which self-assembly reaction occurs forming micellar nanocrystals, with the structures (micelle shape and nanocrystal encapsulation) controlled by the organic solvent used. This method is largely continuous and produces high quality micellar nanocrystal products with an inexpensive structure control approach. By using a water-miscible organic solvent tetrahydrofuran (THF), worm-shaped micellar nanocrystals can be produced due to solvent-induced/facilitated micelle fusion. Compared with the common spherical micellar nanocrystals, worm-shaped micellar nanocrystals can offer minimized non-specific cellular uptake, thus enhancing biological targeting. By co-encapsulating multiple nanocrystals into each micelle, multifunctional or synergistic effects can be achieved. Current limitations of this fabrication method, which will be part of the future work, primarily include imperfect encapsulation in the micellar nanocrystal product and the incompletely continuous nature of the process.

The present work describes a method to fabricate micellar nanocrystals, an emerging major class of nanobiomaterials. This method combines top-down electrospray, bottom-up self-assembly, and solvent-based structure control. The fabrication method is largely continuous, can produce high quality products, and possesses an inexpensive means of structure control.